Appendix ESecure Site ...Three (3) test borings were drilled with two (2) of the test borings used...

Appendix E

Stormwater Report

October 29, 2019 Revised February 7, 2020

STORMWATER REPORT

For

91 HARTWELL AVE Lexington, Massachusetts

Prepared for:

Paul Finger Associates 14 Spring Street

Waltham, Massachusetts 02451-4429

Prepared by:

NITSCH ENGINEERING, INC. 2 Center Plaza, Suite 430

Boston, MA 02108

Nitsch Project #13067

91 Hartwell Ave, Lexington, MA Notice of Intent Stormwater Report Revised February 7, 2020

TABLE OF CONTENTS

1.0 INTRODUCTION ............................................................................................................. 1

2.0 EXISTING CONDITIONS ................................................................................................. 1

2.1 Existing Drainage Infrastructure ....................................................................................... 1

2.2 NRSC Soil Designations .................................................................................................. 1

2.3 On-Site Soil Investigations ............................................................................................... 2

2.4 Wetland Resource Areas ................................................................................................. 2

2.5 Total Maximum Daily Load (TMDL) .................................................................................. 2

3.0 PROPOSED CONDITIONS ............................................................................................. 2

3.1 Project Description ........................................................................................................... 2

3.2 Stormwater Management System .................................................................................... 3

3.3 Stormwater Management During Construction ................................................................. 5

4.0 STORMWATER MANAGEMENT ANALYSIS ................................................................. 5

4.1 Methodology .................................................................................................................... 5

4.2 HydroCAD Version 10.00 ................................................................................................. 5

4.3 Precipitation Data ............................................................................................................ 6

4.4 Existing Hydrologic Conditions ......................................................................................... 6

4.5 Proposed Hydrologic Conditions ...................................................................................... 6

4.6 Peak Flow Rates .............................................................................................................. 6

4.7 Runoff Volumes ............................................................................................................... 7

4.8 Compensatory Storage .................................................................................................... 7

5.0 MASSDEP STORMWATER MANAGEMENT STANDARDS .......................................... 7

Standard 1: No New Untreated Discharges ................................................................................ 8

Standard 2: Peak Rate Attenuation ........................................................................................... 8

Standard 3: Groundwater Recharge .......................................................................................... 8


Standard 4: Water Quality Treatment ........................................................................................ 8

Standard 5: Land Uses with Higher Potential Pollutant Loads ................................................... 8

Standard 6: Critical Areas ......................................................................................................... 9

Standard 7: Redevelopments .................................................................................................... 9

Standard 8: Construction Period Pollution Prevention and Sedimentation Control .................... 9

Standard 9: Operation and Maintenance Plan ........................................................................... 9

Standard 10: Prohibition of Illicit Discharges ............................................................................. 9

6.0 CLOSED DRAINAGE SYSTEM DESIGN ........................................................................ 9

7.0 CONCLUSION ................................................................................................................10

FIGURES DR-1 Existing Watershed Areas DR-2 Proposed Watershed Areas APPENDICES

APPENDIX A STORMWATER MANAGEMENT STANDARDS DOCUMENTATION MassDEP Checklist for Stormwater Report Standard 4: TSS Removal Calculations Standard 10: Illicit Discharge Compliance Statement

Appendix B Existing Conditions – HydroCAD Calculations

Appendix C Proposed Conditions – HydroCAD Calculations

Appendix D Long-Term Pollution Prevention and Stormwater Operation and

Maintenance Plan

Appendix E Soil Investigations NRCS Soil Maps and Descriptions Preliminary Design Geotechnical Memo

Appendix F DRAFT Stormwater Pollution Prevention Plan (SWPPP)

Appendix G Porous Asphalt System Design Information


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1.0 INTRODUCTION

Nitsch Engineering has prepared this Stormwater Report to support the Notice of Intent (NOI) application to the Town of Lexington for the 91 Hartwell Avenue project (subsequently referred to as the “Project”) located in Lexington, Massachusetts. The project site is located at 91 Hartwell Avenue in Lexington, Massachusetts (subsequently referred to as the “Site”). The Project includes the redevelopment of the existing office park with the construction of a new four (4) level above grade parking garage and a new two (2) story lab/office building. The Project will include various site improvements including the reconfiguration of an existing driveway and parking areas, installation of new utilities to support the proposed buildings, and a stormwater management system. The proposed stormwater management system has been designed to comply with the requirements of the Lexington Wetlands Protection Code and the Massachusetts Department of Environmental Protection (DEP) Stormwater Management Standards.

2.0 EXISTING CONDITIONS

The Site is located at 91 Hartwell Avenue in Lexington, Massachusetts at the intersection of Hartwell Place and Hartwell Avenue. The Site is bounded by Hartwell Avenue to the East, Hartwell Place and an existing office building to the south, and wetlands to the west and north. The Site currently consists of a 3-story commercial building, a large surface parking lot with landscaped islands and drainage swales, and undeveloped conservation land. Access to the parking lot is provided by a driveway entrance from Hartwell Avenue located east of the existing building, as well as from Hartwell Place located south of the existing building. The Site includes wetlands along its western, northern, and eastern edges. The proposed development including the parking garage and lab/office building are planned on the location of the existing parking lot. The topography of the site is relatively flat with grades gently sloping away from the existing building to the perimeter of the site towards the wetlands. 2.1 Existing Drainage Infrastructure

Stormwater generated by the existing Site flows overland directly to the wetland along the western and northern edge of the Site. Drainage in Hartwell Place is collected using catch basins and is piped via a closed drainage system to one of six (6) discharge locations around the site. There is a 30-inch reinforced concrete pipe (RCP) from Hartwell Place that discharges through a headwall which conveys stormwater generated from Hartwell Place and the existing building, a 12-inch culvert which conveys stormwater generated from the landscaped area south and west of the existing building, and a 12-inch RCP outlet pipe that conveys stormwater from the smaller wetland located east of the existing building to the larger wetland. Additionally, stormwater generated from the existing surface parking lot discharges to the adjacent wetland via two (2) 12-inch RCP pipes and a triple barrel culvert consisting of three (3) 12-inch RCP pipes. All outlets discharge to the wetland with little or no wetland mitigation. The existing stormwater management system was constructed prior to the 2008 MassDEP Stormwater Management Standards and the Site provides minimal peak flow attenuation, water quality treatment, and groundwater recharge. The adjacent wetlands to the north, west and south of the Site are tributary to the Shawsheen River.. 2.2 NRSC Soil Designations

The Soil Classification Summary (Table 1) outlines the Natural Resources Conservation Services (NRCS) designation of the soil series at the Site. The majority of soils on the project site are classified as Urban Land, Wet Substratum with an unclassified hydrologic soil group (HSG) rating. It is assumed


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based on the Urban Land complex and proximity to wetlands that all soils on site are to be classified as HSG D, indicating that the soils have minimal infiltration capacities. Refer to the NRCS Soil Maps and Descriptions in Appendix E. Table 1 - NRCS Soil Classification Summary

Soil Unit Soil Series Hydrologic Soil Group

52A Freetown muck, 0 to 1 percent slopes

B/D

603 Urban land, wet substratum -

656 Udorthents-Urban land complex -

2.3 On-Site Soil Investigations

A Preliminary Design Geotechnical Memo was provided by Haley & Aldrich, Inc. summarizing their findings at the Site from explorations performed on August 22 & 23, 2018. Three (3) test borings were drilled with two (2) of the test borings used to conduct falling-head permeability tests and one (1) test boring was completed as a groundwater observation well. Groundwater was observed at approximate elevation 115.0’ and the results of the falling head permeability test revealed infiltration rates ranging from 2x10E-05 to 6X10E-05 cm/sec. Exfiltration was not used in the stormwater analysis of the proposed stormwater management system. The results of the borings were consistent throughout the Site and indicated a 3 to 4-foot-thick layer of miscellaneous fill overlying loose to medium dense fine-grained silty soils. These results correspond with the soils used in the stormwater analysis classified as HSG D with no infiltration. Refer to Appendix E for the Geotechnical Memo. 2.4 Wetland Resource Areas

There are two (2) Bordering Vegetated Wetlands (BVW) jurisdictional under the Massachusetts Wetlands Protection Act located on the Site. The BVWs and their associated 100-foot Buffer Zones are shown on the enclosed plans. Refer to the NOI Application Report for additional resource area information. 2.5 Total Maximum Daily Load (TMDL)

The Site is tributary to the Shawsheen river.. The Site is located within the Shawsheen Watershed and will potentially be subject to a Draft Pathogen Total Maximum Daily Load (TMDL) if it is finalized by MassDEP. The Project has been designed to minimize stormwater discharge and associated pathogen pollutants through the proposed BMPs to meet the intent of the TMDL.

3.0 PROPOSED CONDITIONS

3.1 Project Description

The Project includes the redevelopment of the existing office park with the construction of a new four (4) level above grade parking garage and a new two (2) story lab/office building. The project will include various site improvements including reconfiguration of an existing driveway and parking areas, installation of new utilities to support the proposed buildings, and a stormwater management system.


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The WPA classifies the proposed Project as “Redevelopment”. It decreases the overall impervious area for the Site by approximately 0.51 acres compared to current existing conditions. The Lexington Wetland Protection Code however requires all existing impervious surfaces to be considered “open space in good condition (as defined by NRCS TR-55) where the impervious surface is to be demolished and replaced with a different ground cover. While the site may be considered “open space in good condition’ the high groundwater table and soil characteristics technically have the site’s condition functioning as almost impervious. The proposed stormwater management system has been designed to comply with and exceed the requirements of the Lexington Wetlands Protection Code and the Massachusetts Department of Environmental Protection (DEP) Stormwater Management Standards. Refer to Table 2 for a comparison of the existing and proposed land use for the Site. Table 2 - Proposed land use for 91 Hartwell Avenue (in acres)

Land Use Existing Site*

(acres) Proposed Site

(acres) Change

Buildings 0.94 2.95 + 2.01

Site Pavement 0.69 0.52 - 0.17

Open Space 5.84 4.00** - 1.84

Total 7.47 7.47 ---

*Existing Site areas reflect change in ground cover per Lexington Wetland Protection Code. **The project includes 0.13 acres of porous asphalt, which is included as Open Space above and conservatively

included as impervious area in the HydroCAD stormwater analysis.

3.2 Stormwater Management System

The Project will include the installation of a stormwater management system that has been designed to comply with the requirements of the Lexington Wetlands Protection Code and the Massachusetts Department of Environmental Protection (DEP) Stormwater Management Standards. The Project has been designed using environmentally-sensitive site design and low impact development (LID) techniques. This design prevents the generation of stormwater and non-point source pollution by reducing impervious surfaces compared to current conditions with porous asphalt, disconnecting flow paths, treating stormwater at its source, and protecting natural processes. Stormwater systems have been designed to replicate natural hydrologic features of the site prior to any development. The proposed stormwater management system does not include the use of any closed drainage system features (i.e. catch basins and manholes with piped connections and discharges) except for a single overflow device to an existing culvert discharging to the wetland. Instead, a LID approach to the stormwater management system is proposed to mimic the pre-development conditions of the Site. Level spreaders and emergency spillways are proposed to minimize concentrated flow. The proposed stormwater management system for the Project includes the construction of three (3) open wet basins, a sediment forebay, a porous asphalt system, and a blue roof which were designed using the guidelines provided in the DEP Stormwater Management Standards. The eastern portion of the site including the porous asphalt roadway and a portion of the lab/office building roof will drain overland to the proposed porous asphalt system and adjacent wet basins. Overflow from these basins will connect directly to an existing 24-inch reinforced concrete pipe (RCP) via a new 12-inch drain pipe and ultimately to the wetland.


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The new paved roadway and parking garage roof along with adjacent landscaped areas at the western end of the Site will drain overland to a sediment forebay for pretreatment prior to discharge to a wet basin. The wet basin will then overflow to the adjacent constructed wetland constructed for wetland replication. All remaining lab/office roof runoff with discharge to level spreaders along the northern edge of the building and ultimately to the wetland. The sediment forebay and wet basins have been sized to provide the required water quality volume. Additionally, approximately 11,500 square feet (sf) of lab/office roof area has been designated for use as a blue roof. Porous Asphalt

One porous asphalt roadway totaling approximately 0.13 acres is proposed in an area that will not be frequently travelled by vehicles. This area will be used by delivery trucks and emergency vehicles only as required during emergencies. The porous asphalt will replace traditional impervious roadways and allow runoff to be treated and infiltrated within the pavement section. The filter course and reservoir course were sized according to the University of New Hampshire Design Specifications for Porous Asphalt Pavement and Infiltration Beds. The porous asphalt systems are sized to store and treat a portion of the required water quality volume. Along with the contributing drainage area of the porous asphalt roadway itself, a portion of the proposed lab/office building roof will daylight to the exterior of the building and drain overland to the porous asphalt system. The porous asphalt roadway drains towards a low point along the length the porous asphalt road adjacent to a proposed wet basin. The location of the low point and adjacent wet basin are essentially a back-up system for the porous asphalt system to allow any surcharged stormwater reaching the surface of the roadway to drain freely to the basin and ultimately to the existing wetland. See Appendix G for porous asphalt design information. Wet Basin with Sediment Forebay

A wet basin with a sediment forebay for pretreatment is proposed to treat stormwater runoff generated by the proposed roadway between the new parking garage and lab/office building, along with the surface runoff generated from the upper level of the parking garage and adjacent landscaped areas. Pretreatment for the wet basin will be provided by a sediment forebay to meet the 80% TSS removal standard set forth by the MADEP Stormwater Handbook. The proposed forebay was designed to improve water quality of the runoff generated from the new impervious surfaces traveled by vehicles. Runoff from the roadway will be conveyed to a curb cut where it will discharge directly to the sediment forebay. The forebay will then overflow across the driveway through a shallow trench drain and discharge to the wet basin. The sediment forebay was designed in accordance with the MassDEP Stormwater Management Handbook to provide a water quality volume (WQV) equivalent to 0.1 inches per impervious acre:

Tributary Impervious Area = 58,189 sf WQV Required = 58,189 sf * (0.1 in. / 12 in./ft) = 485 cf WQV Provided in Forebay = 1,928 cf

The sediment forebay is proposed to include an impervious liner to increase the potential sediment storage volume due to the high groundwater. The wet basin will then overflow to the adjacent constructed wetland. Stormwater Outfalls with Level Spreaders

A level spreader will be included at all garage and lab/office building roof drain discharge locations. Runoff generated from portions of the new garage and lab/office building roof will daylight via roof


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leaders to a gravel infiltration trench with level spreader. These level spreaders will receive concentrated flow and convert it to sheet flow so it can disperse uniformly across a stable slope.

Refer to the TSS Removal spreadsheets in Appendix A for TSS removal summaries for each treatment train. Blue Roof Per the Lexington Wetlands Protection Code, any proposed project that discharges to a resource area shall not result in an increase in the total volume of surface runoff for the 1-year return period storm at all design points. The majority of peak runoff volume mitigation for the Project is accomplished with the use of stormwater wet basins, sediment forebay, and porous asphalt. The remaining increase in runoff volume to be mitigated is accounted for by the blue roof via the containment of the 1-year rainfall event (2.59-inches). Approximately 11,500 sf of lab/office building roof area has been designated for use as a blue roof to provide stormwater runoff volume reduction for the 1-year rainfall event.

3.3 Stormwater Management During Construction

The Site Contractor will be responsible for stormwater management of the active construction site and is required to adhere to the conditions of the 2012 Construction General Permit under the Environmental Protection Agency (through the preparation and implementation of a SWPPP), Town of Lexington Conservation Commission, and MassDEP. A draft SWPPP has been prepared in accordance with the MassDEP Stormwater Management Standards and the 2017 Construction General Permit (Appendix F).

4.0 STORMWATER MANAGEMENT ANALYSIS

4.1 Methodology

Nitsch Engineering completed a hydrologic analysis of the existing project site utilizing Soil Conservation Service (SCS) Runoff Curve Number (CN) methodology. The SCS method calculates the rate at which the runoff reaches the design point considering several factors: the slope and flow lengths of the subcatchment area, the soil type of the subcatchment area, and the type of surface cover in the subcatchment area. HydroCAD Version 10.00 computer modeling software was used in conjunction with the SCS method to determine the peak runoff rates and runoff volumes for the 2-, 10-, 25-, and 100-year, 24-hour rainfall events. The proposed project site is being analyzed with the same methodology. The Site consists of a single subcatchment, or drainage area, draining overland or through various outlet pipes to the adjacent wetland along the boundary of the site for the existing conditions analysis. The Site was divided into multiple subcatchments for the proposed conditions analysis. A single design point representing the adjacent wetland was used in the analysis. For each subcatchment area, SCS Runoff Curve Numbers (CNs) were selected by using the cover type and hydrologic soil group of each area. The peak runoff rates and runoff volumes for the 2-, 10-, 25- and 100-year 24-hour rainfall events were then determined by inputting the drainage areas, CNs, and time of concentration (Tc) paths into the HydroCAD model. For purposes of the overall drainage model the porous asphalt area was considered to be impervious surface for a conservative estimate. Additionally, the wet basin with sediment forebay BMP was not modeled as it is not anticipated to provide a noticeable peak flow reduction and is utilized for water quality functions. 4.2 HydroCAD Version 10.00

The HydroCAD computer program uses SCS and TR-20 methods to model drainage systems. TR-20 (Technical Release 20) was developed by the Soil Conservation Service to estimate runoff and peak


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discharges in small watersheds. TR-20 is generally accepted by engineers and reviewing authorities as the standard method for estimating runoff and peak discharges. HydroCAD Version 10.00 uses up to four types of components to analyze the hydrology of a given site: subcatchments, reaches, basins, and links. Subcatchments are areas of land that produce surface runoff. The area, weighted CN, and Tc characterize each individual subcatchment area. Reaches are generally uniform streams, channels, or pipes that convey water from one point to another. A basin is any impoundment that fills with water from one or more sources and empties via an outlet structure. Links are used to introduce hydrographs into a project from another source or to provide a junction for more than one hydrograph within a project. The time span for the model was set for 0-48 hours in order to prevent truncation of the hydrograph. 4.3 Precipitation Data

The National Oceanic and Atmospheric Administration Atlas 14 precipitation frequency estimates were used to calculate the 1-, 2-, 10-, 25-, and 100- year 24-hour rainfall events in HydroCAD. See table below for rainfall depths. Rainfall Event 24–hour Rainfall 1-year 2.59 in. 2-year 3.22 in. 10-year 5.09 in. 25-year 6.26 in. 100-year 8.06 in. 4.4 Existing Hydrologic Conditions

As summarized in Section 2.1, Nitsch Engineering delineated the project site into a single subcatchment area discharging to a single Design Point (DP) utilizing an existing conditions survey and on-site observations (See Figure DR-1). The design point (DP) is defined as the wetland along the boundary of the site where all runoff generated from the Site discharges to. The HydroCAD model for existing conditions is provided in Appendix B.

4.5 Proposed Hydrologic Conditions

The proposed project has been designed to mitigate the change in stormwater runoff at the DP as required by the DEP Stormwater Management Standards and the Town of Lexington Wetlands Protection Code. The existing watershed areas were modified to reflect the proposed topography, stormwater management system, and roof areas. (See Figure DR-2). The HydroCAD model for the proposed conditions is provided in Appendix C and results from the calculations are summarized in Table 3. 4.6 Peak Flow Rates

The proposed stormwater management system is expected to reduce the proposed peak runoff rates to at or below the existing rates for Design Point DP-1. Table 3 below summarize the existing and proposed hydrologic analyses for the site at the design point. Table 3 - Peak Rates of Runoff for Design Point DP-1 (in cfs)

Storm Event 2-year 10-year 25-year 100-year

Existing 9.49 18.61 24.43 33.37

Proposed 9.29 16.55 22.90 27.46


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4.7 Runoff Volumes

As noted in Section 3.2, the Lexington Wetlands Protection Code, any proposed project that discharges to a resource area shall not result in an increase in the total volume of surface runoff for the 1-year return period storm. The hydrologic model for the project accounts for volume storage mitigation provided by the volume-based site BMPs. The blue roof volume was excluded from the site hydrologic model because this feature is part of the building structure and will also have a negligible effect on the analyses of higher intensity storm events. The summary pages for the existing site conditions (App. B, page 4) and the proposed site conditions (App. C, page 4) list runoff volumes for the project site of 0.739 ac-ft and 0.796 ac-ft respectively. The listed increase in runoff volume of 0.057ac-ft (2,482 cf) will be retained within the 11,500sf of roof area designated as a blue roof. During a 1-year rainfall event, the 2.59 inches of rainfall collected over this area will equate to 2,482 cf of retained volume and is proposed as mitigation for the estimated increase in runoff volume in the hydrologic model. Due to the relatively low soil permeability and high groundwater conditions, coupled with spatial and topographic constraints of the site, the rainwater collected by the blue roof will be discharged via an extended detention method which will release collected water onto the standard building roof over the course of a 3-day (72 hour) period. The resulting discharge rate will be approximately 0.001 cfs (4.3 gpm), essentially removing the collected volume from the ordinary stormwater discharges from the site. 4.8 Compensatory Storage

The majority of the Site is located within Bordering Land Subject to Flooding (BLSF), or within the 100-year floodplain, and consequently the 10-year floodplain. According to the July 6, 2016 Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps (FIRM) for Middlesex County, Massachusetts (Community Panel Number: 25017C0384F), FEMA Flood Profile Data, and topographic survey by Precision Land Surveying, Inc., most of the Site is located within Zone AE (Elevation 118.5 NAVD88). The 10-year floodplain elevation is 117.25 NAVD88. The proposed redevelopment includes the filling of floodplain with the construction of the new structures. Compensatory storage is provided for all flood storage volume that will be lost as a result of the Project within Bordering Land Subject to Flooding per 310 CMR 10.57(4)(a)1. The compensatory storage is incrementally equal to the volume of flood water at each elevation, up to and including the 100-year flood elevation, that is displaced by the Project and has an unrestricted hydraulic connection to the same water body. Refer to Nitsch Engineering’s floodplain mitigation summary letter to Paul Finger Associates dated February 7, 2020 for a description of the proposed mitigation and floodplain storage volume analysis.

5.0 MassDEP Stormwater Management Standards

The Project is considered a redevelopment under the MADEP Stormwater Handbook Stormwater Management Standards. As such, the project is required to meet Standards 2, 3, and the pretreatment and structural best management practice requirements of Standards 4,5, and 6 only to the maximum extent practicable. Existing stormwater discharges need to comply with Standard 1 only to the maximum extent practicable. The project will comply with all other Standards. The site will be designed to meet or meet to the maximum extent practicable the MassDEP Stormwater Management Standards as summarized below:


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Standard 1: No New Untreated Discharges

The Project will not discharge any untreated stormwater directly to or cause erosion in wetlands or waters of the Commonwealth. Stormwater from the Site will be collected and treated in accordance with the MassDEP Stormwater Management Standards and stormwater outfalls will be stabilized to prevent erosion. Standard 2: Peak Rate Attenuation

The proposed stormwater management system will be designed so that the post-development peak discharge rates do not exceed pre-development peak discharge rates. To prevent storm damage and downstream flooding, the proposed stormwater management practices will mitigate peak runoff rates for the 2-, 10-, 25- and 100-year, 24 hour rainfall events. Refer to Table 3 for a pre- and post- development peak runoff rate comparison. Standard 3: Groundwater Recharge

The Site was designed using environmentally-sensitive site design, low impact development techniques, and stormwater BMP treatment trains to minimize the loss of annual recharge to groundwater. The annual recharge from the post-development site will approximate the annual recharge from pre-development conditions based on soil type using the guidelines provided in the MassDEP Stormwater Management Handbook. Impervious Area = 3.60 acres (includes 0.13 acres porous asphalt) Rv (Recharge Volume) = 0.1 in. / (12 inches/ft) x 3.60 acres x 43,560 sf/acre = 1,307 cubic feet The porous asphalt system is sized to exceed the recharge volume required under the MassDEP Stormwater Management Standards (Table 4) although the on-site soils are not conducive to infiltration and the stormwater analysis did not include infiltration as a conservative approach. Due to the nature of wet basins, the groundwater recharge will be accomplished by the porous asphalt system only. Table 4 - Proposed Recharge Volumes for Stormwater BMPs

Infiltration BMP Recharge Volume (cf)

Porous Asphalt 15,522

Standard 4: Water Quality Treatment

The proposed stormwater management system is designed to remove at least 80% of the average annual post-construction load of Total Suspended Solids (TSS). The proposed structural stormwater BMPs include a wet basin with sediment forebay and porous asphalt system which are sized to capture the required water quality volume and remove a minimum of 80% of total suspended solids. Refer to Appendix A for supporting documentation. Source control and pollution prevention measures, such as street sweeping, proper snow management, and stabilization of eroded surfaces, are included in the Long-Term Pollution Prevention Plan and Operation and Maintenance Plan provided in Appendix D. Standard 5: Land Uses with Higher Potential Pollutant Loads

The proposed project site does not contain any land uses with higher potential pollutant loads. Therefore, this standard is not applicable.


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Standard 6: Critical Areas

The Project is not located within any critical areas. Therefore, this standard is not applicable. Standard 7: Redevelopments

The Project is located on a previously developed site and results in a net decrease in impervious area. Therefore, the project is considered a redevelopment under the DEP Stormwater Management Standards. A redevelopment project is required to meet the following Stormwater Management Standards only to the maximum extent practicable: Standard 2, Standard 3, and the pretreatment and structural stormwater best management practice requirements of Standards 4, 5, and 6. A redevelopment project must comply with all other requirements of the Stormwater Management Standards and improve existing conditions. Standard 8: Construction Period Pollution Prevention and Sedimentation Control

A plan to control construction-related impacts, including erosion, sedimentation, and other pollutant sources during construction and land disturbance activities (construction period erosion, sedimentation, and pollution prevention plan) will be developed and implemented during the Notice of Intent permitting process. Since the Project will disturb more than one (1) acre of land, a Notice of Intent will be submitted to the Environmental Protection Agency (EPA) for coverage under the National Pollution Discharge Elimination System (NPDES) Construction General Permit. As part of this application the Applicant is required to prepare a Stormwater Pollution Prevention Plan (SWPPP) and implement the measures in the SWPPP. The SWPPP, which is to be kept on site, includes erosion and sediment controls (stabilization practices and structural practices), temporary and permanent stormwater management measures, Contractor inspection schedules and reporting of all SWPPP features, materials management, waste disposal, off-site vehicle tracking, spill prevention and response, sanitation, and non-stormwater discharges. A draft SWPPP is provided in Appendix F. Standard 9: Operation and Maintenance Plan

A post-construction operation and maintenance plan has been prepared and will be implemented to ensure that stormwater management systems function as designed. Source control and stormwater BMP operation requirements for the academic campus are summarized in the Long-Term Pollution Prevention Plan and Operation and Maintenance Plan provided in Appendix D. Standard 10: Prohibition of Illicit Discharges

There will be no illicit discharges to the stormwater management system associated with the Project. An Illicit Discharge Compliance Statement is provided in Appendix A.

6.0 CLOSED DRAINAGE SYSTEM DESIGN

The proposed stormwater management system does not include the use of any closed drainage system features (i.e. catch basins and manholes with piped connections and discharges). Instead, a LID approach to the stormwater management system is proposed to mimic the pre-development conditions of the Site including curb cuts to allow surface runoff to drain overland to BMPs, porous asphalt system, and wet basins.


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7.0 CONCLUSION

In conclusion, the Project’s stormwater management system will reduce or maintain peak runoff rates through the widespread use of detention BMPs including porous asphalt and wet basins and improve the water quality of stormwater being discharged from the Site. Environmentally sensitive site design and low impact development techniques will be implemented throughout the Site. The Project is being designed to meet and exceed the MassDEP Stormwater Management Standards and the Town of Lexington Wetlands Protection Code.

91 Hartwell Ave, Lexington, MA Notice of Intent Stormwater Report Revised January 20, 2020

FIGURES

DR-1 Existing Watershed Areas

DR-2 Proposed Watershed Areas

91 Hartwell Ave, Lexington, MA Notice of Intent Stormwater Report October 25, 2019

APPENDIX A

Stormwater Management Standards Documentation

MassDEP Checklist for Stormwater Report

Standard 4: TSS Removal Calculations

Standard 10: Illicit Discharge Compliance Statement

swcheck • 04/01/08 Stormwater Report Checklist • Page 1 of 8

Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program

Checklist for Stormwater Report

A. Introduction

Important: When filling out forms on the computer, use only the tab key to move your cursor - do not use the return key.

A Stormwater Report must be submitted with the Notice of Intent permit application to document compliance with the Stormwater Management Standards. The following checklist is NOT a substitute for the Stormwater Report (which should provide more substantive and detailed information) but is offered here as a tool to help the applicant organize their Stormwater Management documentation for their Report and for the reviewer to assess this information in a consistent format. As noted in the Checklist, the Stormwater Report must contain the engineering computations and supporting information set forth in Volume 3 of the Massachusetts Stormwater Handbook. The Stormwater Report must be prepared and certified by a Registered Professional Engineer (RPE) licensed in the Commonwealth. The Stormwater Report must include:

• The Stormwater Checklist completed and stamped by a Registered Professional Engineer (see page 2) that certifies that the Stormwater Report contains all required submittals.1 This Checklist is to be used as the cover for the completed Stormwater Report.

• Applicant/Project Name

• Project Address

• Name of Firm and Registered Professional Engineer that prepared the Report

• Long-Term Pollution Prevention Plan required by Standards 4-6

• Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan required by Standard 82

• Operation and Maintenance Plan required by Standard 9 In addition to all plans and supporting information, the Stormwater Report must include a brief narrative describing stormwater management practices, including environmentally sensitive site design and LID techniques, along with a diagram depicting runoff through the proposed BMP treatment train. Plans are required to show existing and proposed conditions, identify all wetland resource areas, NRCS soil types, critical areas, Land Uses with Higher Potential Pollutant Loads (LUHPPL), and any areas on the site where infiltration rate is greater than 2.4 inches per hour. The Plans shall identify the drainage areas for both existing and proposed conditions at a scale that enables verification of supporting calculations.

As noted in the Checklist, the Stormwater Management Report shall document compliance with each of the Stormwater Management Standards as provided in the Massachusetts Stormwater Handbook. The soils evaluation and calculations shall be done using the methodologies set forth in Volume 3 of the Massachusetts Stormwater Handbook. To ensure that the Stormwater Report is complete, applicants are required to fill in the Stormwater Report Checklist by checking the box to indicate that the specified information has been included in the Stormwater Report. If any of the information specified in the checklist has not been submitted, the applicant must provide an explanation. The completed Stormwater Report Checklist and Certification must be submitted with the Stormwater Report.

1 The Stormwater Report may also include the Illicit Discharge Compliance Statement required by Standard 10. If not included in the Stormwater Report, the Illicit Discharge Compliance Statement must be submitted prior to the discharge of stormwater runoff to the post-construction best management practices. 2 For some complex projects, it may not be possible to include the Construction Period Erosion and Sedimentation Control Plan in the Stormwater Report. In that event, the issuing authority has the discretion to issue an Order of Conditions that approves the project and includes a condition requiring the proponent to submit the Construction Period Erosion and Sedimentation Control Plan before commencing any land disturbance activity on the site.




Checklist (continued)

LID Measures: Stormwater Standards require LID measures to be considered. Document what environmentally sensitive design and LID Techniques were considered during the planning and design of the project:

No disturbance to any Wetland Resource Areas

Site Design Practices (e.g. clustered development, reduced frontage setbacks)

Reduced Impervious Area (Redevelopment Only)

Minimizing disturbance to existing trees and shrubs

LID Site Design Credit Requested:

Credit 1

Credit 2

Credit 3

Use of “country drainage” versus curb and gutter conveyance and pipe

Bioretention Cells (includes Rain Gardens)

Constructed Stormwater Wetlands (includes Gravel Wetlands designs)

Treebox Filter

Water Quality Swale

Grass Channel

Green Roof

Other (describe):

Wet Basins, Porous Asphalt, Sediment Forebays, Level Spreaders

Standard 1: No New Untreated Discharges

No new untreated discharges

Outlets have been designed so there is no erosion or scour to wetlands and waters of the Commonwealth

Supporting calculations specified in Volume 3 of the Massachusetts Stormwater Handbook included.





Standard 2: Peak Rate Attenuation

Standard 2 waiver requested because the project is located in land subject to coastal storm flowage and stormwater discharge is to a wetland subject to coastal flooding.

Evaluation provided to determine whether off-site flooding increases during the 100-year 24-hour storm.

Calculations provided to show that post-development peak discharge rates do not exceed pre-

development rates for the 2-year and 10-year 24-hour storms. If evaluation shows that off-site flooding increases during the 100-year 24-hour storm, calculations are also provided to show that post-development peak discharge rates do not exceed pre-development rates for the 100-year 24-hour storm.

Standard 3: Recharge

Soil Analysis provided.

Required Recharge Volume calculation provided.

Required Recharge volume reduced through use of the LID site Design Credits.

Sizing the infiltration, BMPs is based on the following method: Check the method used.

Static Simple Dynamic Dynamic Field1

Runoff from all impervious areas at the site discharging to the infiltration BMP.

Runoff from all impervious areas at the site is not discharging to the infiltration BMP and calculations

are provided showing that the drainage area contributing runoff to the infiltration BMPs is sufficient to generate the required recharge volume.

Recharge BMPs have been sized to infiltrate the Required Recharge Volume.

Recharge BMPs have been sized to infiltrate the Required Recharge Volume only to the maximum extent practicable for the following reason:

Site is comprised solely of C and D soils and/or bedrock at the land surface

M.G.L. c. 21E sites pursuant to 310 CMR 40.0000

Solid Waste Landfill pursuant to 310 CMR 19.000

Project is otherwise subject to Stormwater Management Standards only to the maximum extent practicable.

Calculations showing that the infiltration BMPs will drain in 72 hours are provided.

Property includes a M.G.L. c. 21E site or a solid waste landfill and a mounding analysis is included.

1 80% TSS removal is required prior to discharge to infiltration BMP if Dynamic Field method is used.





Standard 3: Recharge (continued)

The infiltration BMP is used to attenuate peak flows during storms greater than or equal to the 10-

year 24-hour storm and separation to seasonal high groundwater is less than 4 feet and a mounding analysis is provided.

Documentation is provided showing that infiltration BMPs do not adversely impact nearby wetland resource areas.

Standard 4: Water Quality

The Long-Term Pollution Prevention Plan typically includes the following:

• Good housekeeping practices;

• Provisions for storing materials and waste products inside or under cover;

• Vehicle washing controls;

• Requirements for routine inspections and maintenance of stormwater BMPs;

• Spill prevention and response plans;

• Provisions for maintenance of lawns, gardens, and other landscaped areas;

• Requirements for storage and use of fertilizers, herbicides, and pesticides;

• Pet waste management provisions;

• Provisions for operation and management of septic systems;

• Provisions for solid waste management;

• Snow disposal and plowing plans relative to Wetland Resource Areas;

• Winter Road Salt and/or Sand Use and Storage restrictions;

• Street sweeping schedules;

• Provisions for prevention of illicit discharges to the stormwater management system;

• Documentation that Stormwater BMPs are designed to provide for shutdown and containment in the event of a spill or discharges to or near critical areas or from LUHPPL;

• Training for staff or personnel involved with implementing Long-Term Pollution Prevention Plan;

• List of Emergency contacts for implementing Long-Term Pollution Prevention Plan.

A Long-Term Pollution Prevention Plan is attached to Stormwater Report and is included as an attachment to the Wetlands Notice of Intent.

Treatment BMPs subject to the 44% TSS removal pretreatment requirement and the one inch rule for calculating the water quality volume are included, and discharge:

is within the Zone II or Interim Wellhead Protection Area

is near or to other critical areas

is within soils with a rapid infiltration rate (greater than 2.4 inches per hour)

involves runoff from land uses with higher potential pollutant loads.

The Required Water Quality Volume is reduced through use of the LID site Design Credits.

Calculations documenting that the treatment train meets the 80% TSS removal requirement and, if applicable, the 44% TSS removal pretreatment requirement, are provided.





Standard 4: Water Quality (continued)

The BMP is sized (and calculations provided) based on:

The ½” or 1” Water Quality Volume or

The equivalent flow rate associated with the Water Quality Volume and documentation is provided showing that the BMP treats the required water quality volume.

The applicant proposes to use proprietary BMPs, and documentation supporting use of proprietary

BMP and proposed TSS removal rate is provided. This documentation may be in the form of the propriety BMP checklist found in Volume 2, Chapter 4 of the Massachusetts Stormwater Handbook and submitting copies of the TARP Report, STEP Report, and/or other third party studies verifying performance of the proprietary BMPs.

A TMDL exists that indicates a need to reduce pollutants other than TSS and documentation showing

that the BMPs selected are consistent with the TMDL is provided.

Standard 5: Land Uses With Higher Potential Pollutant Loads (LUHPPLs)

The NPDES Multi-Sector General Permit covers the land use and the Stormwater Pollution

Prevention Plan (SWPPP) has been included with the Stormwater Report.

The NPDES Multi-Sector General Permit covers the land use and the SWPPP will be submitted prior

to the discharge of stormwater to the post-construction stormwater BMPs.

The NPDES Multi-Sector General Permit does not cover the land use.

LUHPPLs are located at the site and industry specific source control and pollution prevention measures have been proposed to reduce or eliminate the exposure of LUHPPLs to rain, snow, snow melt and runoff, and been included in the long term Pollution Prevention Plan.

All exposure has been eliminated.

All exposure has not been eliminated and all BMPs selected are on MassDEP LUHPPL list.

The LUHPPL has the potential to generate runoff with moderate to higher concentrations of oil and grease (e.g. all parking lots with >1000 vehicle trips per day) and the treatment train includes an oil grit separator, a filtering bioretention area, a sand filter or equivalent.

Standard 6: Critical Areas

The discharge is near or to a critical area and the treatment train includes only BMPs that MassDEP

has approved for stormwater discharges to or near that particular class of critical area.

Critical areas and BMPs are identified in the Stormwater Report.





Standard 7: Redevelopments and Other Projects Subject to the Standards only to the maximum extent practicable

The project is subject to the Stormwater Management Standards only to the maximum Extent

Practicable as a:

Limited Project

Small Residential Projects: 5-9 single family houses or 5-9 units in a multi-family development

provided there is no discharge that may potentially affect a critical area.

Small Residential Projects: 2-4 single family houses or 2-4 units in a multi-family development with a discharge to a critical area

Marina and/or boatyard provided the hull painting, service and maintenance areas are protected

from exposure to rain, snow, snow melt and runoff

Bike Path and/or Foot Path

Redevelopment Project

Redevelopment portion of mix of new and redevelopment.

Certain standards are not fully met (Standard No. 1, 8, 9, and 10 must always be fully met) and an

explanation of why these standards are not met is contained in the Stormwater Report.

The project involves redevelopment and a description of all measures that have been taken to

improve existing conditions is provided in the Stormwater Report. The redevelopment checklist found in Volume 2 Chapter 3 of the Massachusetts Stormwater Handbook may be used to document that the proposed stormwater management system (a) complies with Standards 2, 3 and the pretreatment and structural BMP requirements of Standards 4-6 to the maximum extent practicable and (b) improves existing conditions.

Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control

A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan must include the following information:

• Narrative;

• Construction Period Operation and Maintenance Plan;

• Names of Persons or Entity Responsible for Plan Compliance;

• Construction Period Pollution Prevention Measures;

• Erosion and Sedimentation Control Plan Drawings;

• Detail drawings and specifications for erosion control BMPs, including sizing calculations;

• Vegetation Planning;

• Site Development Plan;

• Construction Sequencing Plan;

• Sequencing of Erosion and Sedimentation Controls;

• Operation and Maintenance of Erosion and Sedimentation Controls;

• Inspection Schedule;

• Maintenance Schedule;

• Inspection and Maintenance Log Form.

A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan containing

the information set forth above has been included in the Stormwater Report.





Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control (continued)

The project is highly complex and information is included in the Stormwater Report that explains why it is not possible to submit the Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan with the application. A Construction Period Pollution Prevention and Erosion and Sedimentation Control has not been included in the Stormwater Report but will be submitted before land disturbance begins.

The project is not covered by a NPDES Construction General Permit.

The project is covered by a NPDES Construction General Permit and a copy of the SWPPP is in the

Stormwater Report.

The project is covered by a NPDES Construction General Permit but no SWPPP been submitted.

The SWPPP will be submitted BEFORE land disturbance begins.

Standard 9: Operation and Maintenance Plan

The Post Construction Operation and Maintenance Plan is included in the Stormwater Report and

includes the following information:

Name of the stormwater management system owners;

Party responsible for operation and maintenance;

Schedule for implementation of routine and non-routine maintenance tasks;

Plan showing the location of all stormwater BMPs maintenance access areas;

Description and delineation of public safety features;

Estimated operation and maintenance budget; and

Operation and Maintenance Log Form.

The responsible party is not the owner of the parcel where the BMP is located and the Stormwater

Report includes the following submissions:

A copy of the legal instrument (deed, homeowner’s association, utility trust or other legal entity) that establishes the terms of and legal responsibility for the operation and maintenance of the project site stormwater BMPs;

A plan and easement deed that allows site access for the legal entity to operate and maintain

BMP functions.

Standard 10: Prohibition of Illicit Discharges

The Long-Term Pollution Prevention Plan includes measures to prevent illicit discharges;

An Illicit Discharge Compliance Statement is attached;

NO Illicit Discharge Compliance Statement is attached but will be submitted prior to the discharge of

any stormwater to post-construction BMPs.

91 Hartwell Avenue WATER QUALITY TREATMENT SUMMARY (10/18/2019)

Nitsch Engineering has prepared this Water Quality Treatment Summary for the proposed 91 Hartwell Avenue Project. In compliance with MassDEP Stormwater Management Standard #4, the proposed stormwater management system is designed to remove at least 80% of the average annual post-construction load of TSS prior to discharge. The stormwater management system is designed to remove at least 80% of the average annual post-construction TSS load prior to discharge with the use of a sediment forebay for pretreatment prior to discharge to the constructed pocket wetland. A summary of treatment trains proposed to provide water quantity control and water quality improvement at the proposed project site is provided below.

Treatment Train A

Catchment Areas: PR-1 Sediment Forebay Wet Basin Discharge to Existing Wetland

91 H

art

well

Avenue

Nitsch P

roje

ct N

o. 13067

91 H

art

well

Avenue, Lexin

gto

n, M

A

Octo

ber

18, 2019

Tre

atm

en

t T

rain

A:

S

ed

iment F

ore

ba

y

Pocket W

etland

Dis

charg

e to E

xis

tin

g W

etland

T

reatm

en

t S

pre

ad

sh

eet

B

C

D

E

F

T

SS

Rem

oval

Sta

rtin

g T

SS

A

mount

Rem

ain

ing

BM

P

Rate

Load

R

em

oved (

C*D

) Load

(D

-E)

Wet

Basin

(w

/ p

retr

eatm

en

t)

0.8

0

1.0

0

0.8

0

0.2

0

To

tal T

SS

Rem

ov

al

=

80

%

Meets

80%

TS

S

rem

ov

al re

qu

irem

en

t


APPENDIX B

Existing Conditions – HydroCAD Calculations

PRE-DEVELOPMENT

OVERALL

EX-1

2L

DP-1 WETLAND

Routing Diagram for 13067_HydroCADPrepared by {enter your company name here}, Printed 10/24/2019HydroCAD® 10.00-20 s/n 00546 © 2017 HydroCAD Software Solutions LLC

Subcat Reach Pond Link

91 Hartwell Ave - Existing Conditions

13067_HydroCAD Printed 10/24/2019Prepared by {enter your company name here}

Page 2HydroCAD® 10.00-20 s/n 00546 © 2017 HydroCAD Software Solutions LLC

Area Listing (selected nodes)

Area

(acres)

CN Description

(subcatchment-numbers)

5.843 80 >75% Grass cover, Good, HSG D (EX-1)

0.690 98 Paved parking to Remain in Function, HSG D (EX-1)

0.943 98 Roofs, HSG D (EX-1)

7.476 84 TOTAL AREA

91 Hartwell Ave - Existing Conditions



Soil Listing (selected nodes)

Area

(acres)

Soil

Group

Subcatchment

Numbers

0.000 HSG A

0.000 HSG B

0.000 HSG C

7.476 HSG D EX-1

0.000 Other

7.476 TOTAL AREA

91 Hartwell Ave - Existing ConditionsNOAA 24-hr D 1-Year Rainfall=2.59"13067_HydroCAD

Printed 10/24/2019Prepared by {enter your company name here}Page 4HydroCAD® 10.00-20 s/n 00546 © 2017 HydroCAD Software Solutions LLC

Time span=0.00-72.00 hrs, dt=0.01 hrs, 7201 pointsRunoff by SCS TR-20 method, UH=SCS, Weighted-CN

Reach routing by Stor-Ind method - Pond routing by Stor-Ind method

Runoff Area=325,646 sf 21.84% Impervious Runoff Depth=1.19"Subcatchment EX-1: Flow Length=331' Tc=20.6 min CN=84 Runoff=6.58 cfs 0.739 af

Inflow=6.58 cfs 0.739 afLink 2L: DP-1 WETLAND Primary=6.58 cfs 0.739 af

Total Runoff Area = 7.476 ac Runoff Volume = 0.739 af Average Runoff Depth = 1.19"78.16% Pervious = 5.843 ac 21.84% Impervious = 1.633 ac



Summary for Subcatchment EX-1:

Runoff = 6.58 cfs @ 12.30 hrs, Volume= 0.739 af, Depth= 1.19"

Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.01 hrsNOAA 24-hr D 1-Year Rainfall=2.59"

Area (sf) CN Description

41,070 98 Roofs, HSG D* 30,062 98 Paved parking to Remain in Function, HSG D

254,514 80 >75% Grass cover, Good, HSG D

325,646 84 Weighted Average254,514 78.16% Pervious Area71,132 21.84% Impervious Area

Tc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)

17.0 100 0.0050 0.10 Sheet Flow, Grass: Short n= 0.150 P2= 3.22"

3.3 174 0.0160 0.89 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps

0.3 57 0.0200 3.34 2.62 Pipe Channel, CMP_Round 12"12.0" Round Area= 0.8 sf Perim= 3.1' r= 0.25'n= 0.025 Corrugated metal

20.6 331 Total

Subcatchment EX-1:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

7

6

5

4

3

2

1

0

NOAA 24-hr D

1-Year Rainfall=2.59"

Runoff Area=325,646 sf

Runoff Volume=0.739 af

Runoff Depth=1.19"

Flow Length=331'

Tc=20.6 min

CN=84

6.58 cfs



Summary for Link 2L: DP-1 WETLAND

Inflow Area = 7.476 ac, 21.84% Impervious, Inflow Depth = 1.19" for 1-Year eventInflow = 6.58 cfs @ 12.30 hrs, Volume= 0.739 afPrimary = 6.58 cfs @ 12.30 hrs, Volume= 0.739 af, Atten= 0%, Lag= 0.0 min

Primary outflow = Inflow, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs

Link 2L: DP-1 WETLAND

InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

7

6

5

4

3

2

1

0

Inflow Area=7.476 ac

6.58 cfs6.58 cfs














20.6 331 Total

Subcatchment EX-1:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

10

9

8

7

6

5

4

3

2

1

0

NOAA 24-hr D




Runoff Depth=1.70"

Flow Length=331'

Tc=20.6 min

CN=84

9.49 cfs







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

10

9

8

7

6

5

4

3

2

1

0


9.49 cfs9.49 cfs














20.6 331 Total

Subcatchment EX-1:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

NOAA 24-hr D




Runoff Depth=3.35"

Flow Length=331'

Tc=20.6 min

CN=84

18.61 cfs







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0


18.61 cfs18.61 cfs














20.6 331 Total

Subcatchment EX-1:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

27

26

25

24

23

2221

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

NOAA 24-hr D




Runoff Depth=4.44"

Flow Length=331'

Tc=20.6 min

CN=84

24.43 cfs







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

27

26

25

24

23

2221

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0


24.43 cfs24.43 cfs














20.6 331 Total

Subcatchment EX-1:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

36

34

32

30

28

26

24

22

20

18

16

14

12

10

8

6

4

2

0

NOAA 24-hr D




Runoff Depth=6.15"

Flow Length=331'

Tc=20.6 min

CN=84

33.37 cfs







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

36

34

32

30

28

26

24

22

20

18

16

14

12

10

8

6

4

2

0


33.37 cfs33.37 cfs


APPENDIX C

Proposed Conditions – HydroCAD Calculations

POST-DEVELOPMENT

PR-1

PR-2

PR-3 PR-49P

Stormwater Treatment

Area 1 & 2

22P

Porous Asphalt w/

Check Dams

24P

Forebay/Stormwater

Treatment Area 3

13L

DP-1 WETLAND

Routing Diagram for 13067_HydroCADPrepared by {enter your company name here}, Printed 1/17/2020

HydroCAD® 10.00-20 s/n 00546 © 2017 HydroCAD Software Solutions LLC

Subcat Reach Pond Link

91 Hartwell Ave - Proposed Conditions



Area Listing (selected nodes)

Area

(acres)

CN Description

(subcatchment-numbers)

3.871 80 >75% Grass cover, Good, HSG D (PR-1, PR-2, PR-3, PR-4)

0.518 98 Paved parking, HSG D (PR-1, PR-2, PR-3)

0.134 98 Porous Asphalt, HSG D (PR-3)

2.953 98 Roofs, HSG D (PR-1, PR-2, PR-3)

7.476 89 TOTAL AREA

91 Hartwell Ave - Proposed Conditions



Soil Listing (selected nodes)

Area

(acres)

Soil

Group

Subcatchment

Numbers

0.000 HSG A

0.000 HSG B

0.000 HSG C

7.476 HSG D PR-1, PR-2, PR-3, PR-4

0.000 Other

7.476 TOTAL AREA

91 Hartwell Ave - Proposed ConditionsNOAA 24-hr D 1-Year Rainfall=2.59"13067_HydroCAD




Runoff Area=206,949 sf 34.28% Impervious Runoff Depth=1.32"Subcatchment PR-1: Flow Length=331' Tc=20.6 min CN=86 Runoff=4.67 cfs 0.522 af

Runoff Area=77,321 sf 75.26% Impervious Runoff Depth=1.96"Subcatchment PR-2: Tc=5.0 min CN=94 Runoff=4.04 cfs 0.289 af



Peak Elev=115.61' Storage=1,859 cf Inflow=0.23 cfs 0.064 afPond 9P: Stormwater Treatment Area 1 & 212.0" Round Culvert n=0.011 L=26.0' S=0.0085 '/' Outflow=0.05 cfs 0.030 af

Peak Elev=116.12' Storage=3,657 cf Inflow=0.25 cfs 0.128 afPond 22P: Porous Asphalt w/ Check Dams Outflow=0.12 cfs 0.049 af

Peak Elev=115.19' Storage=3,091 cf Inflow=4.04 cfs 0.289 afPond 24P: Forebay/Stormwater Treatment 18.0" Round Culvert x 2.00 n=0.011 L=50.0' S=0.0050 '/' Outflow=3.44 cfs 0.245 af





Summary for Subcatchment PR-1:




67,081 98 Roofs, HSG D3,866 98 Paved parking, HSG D

* 136,002 80 >75% Grass cover, Good, HSG D






20.6 331 Total

Subcatchment PR-1:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

5

4

3

2

1

0

NOAA 24-hr D




Runoff Depth=1.32"

Flow Length=331'

Tc=20.6 min

CN=86

4.67 cfs







41,337 98 Roofs, HSG D* 16,853 98 Paved parking, HSG D




5.0 Direct Entry,

Subcatchment PR-2:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

4

3

2

1

0

NOAA 24-hr D




Runoff Depth=1.96"

Tc=5.0 min

CN=94

4.04 cfs







20,226 98 Roofs, HSG D* 5,827 98 Porous Asphalt, HSG D

1,829 98 Paved parking, HSG D4,868 80 >75% Grass cover, Good, HSG D

32,750 95 Weighted Average4,868 14.86% Pervious Area

27,882 85.14% Impervious Area


254.0 Direct Entry,

Subcatchment PR-3:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.28

0.26

0.24

0.22

0.2

0.18

0.16

0.14

0.12

0.1

0.08

0.06

0.04

0.02

0

NOAA 24-hr D




Runoff Depth=2.05"

Tc=254.0 min

CN=95

0.25 cfs







0 98 Roofs, HSG D0 98 Paved parking, HSG D




5.0 Direct Entry,

Subcatchment PR-4:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.25

0.24

0.23

0.22

0.21

0.2

0.19

0.18

0.17

0.16

0.15

0.14

0.13

0.12

0.11

0.1

0.09

0.08

0.07

0.06

0.05

0.04

0.03

0.02

0.01

0

NOAA 24-hr D




Runoff Depth=0.95"

Tc=5.0 min

CN=80

0.23 cfs



Summary for Pond 9P: Stormwater Treatment Area 1 & 2

Inflow Area = 0.950 ac, 67.39% Impervious, Inflow Depth = 0.81" for 1-Year eventInflow = 0.23 cfs @ 12.13 hrs, Volume= 0.064 afOutflow = 0.05 cfs @ 22.60 hrs, Volume= 0.030 af, Atten= 80%, Lag= 628.4 minPrimary = 0.05 cfs @ 22.60 hrs, Volume= 0.030 af

Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrsPeak Elev= 115.61' @ 22.60 hrs Surf.Area= 3,417 sf Storage= 1,859 cf

Plug-Flow detention time= 624.2 min calculated for 0.030 af (46% of inflow)Center-of-Mass det. time= 410.2 min ( 1,586.9 - 1,176.8 )

Volume Invert Avail.Storage Storage Description

#1 116.10' 12,046 cf Freeboard (Irregular) Listed below (Recalc)#2 115.00' 2,824 cf Stormwater Treatment Area 2 (Irregular) Listed below (Recalc)#3 115.00' 832 cf Stormwater Treatment Area 1 (Irregular) Listed below (Recalc)

15,702 cf Total Available Storage

Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area(feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft)

116.10 10,475 612.8 0 0 10,475117.25 10,475 612.8 12,046 12,046 11,180


115.00 2,389 278.9 0 0 2,389116.00 3,283 308.2 2,824 2,824 3,789


115.00 333 87.2 0 0 333116.00 631 108.9 474 474 686116.50 802 118.3 357 832 865

Device Routing Invert Outlet Devices

#1 Primary 115.50' 12.0" Round Culvert L= 26.0' RCP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 115.50' / 115.28' S= 0.0085 '/' Cc= 0.900 n= 0.011 Concrete pipe, straight & clean, Flow Area= 0.79 sf

Primary OutFlow Max=0.05 cfs @ 22.60 hrs HW=115.61' (Free Discharge)1=Culvert (Barrel Controls 0.05 cfs @ 1.59 fps)



Pond 9P: Stormwater Treatment Area 1 & 2

InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.25

0.24

0.23

0.22

0.21

0.2

0.19

0.18

0.17

0.16

0.15

0.14

0.13

0.12

0.11

0.1

0.09

0.08

0.07

0.06

0.05

0.04

0.03

0.02

0.01

0


Peak Elev=115.61'

Storage=1,859 cf

12.0"

Round Culvert

n=0.011

L=26.0'

S=0.0085 '/'

0.23 cfs

0.05 cfs



Summary for Pond 22P: Porous Asphalt w/ Check Dams


Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrsStarting Elev= 15.00' Surf.Area= 0 sf Storage= 0 cfPeak Elev= 116.12' @ 18.19 hrs Surf.Area= 37,395 sf Storage= 3,657 cf



#1 116.10' 12,046 cf Custom Stage Data (Irregular) Listed below (Recalc)#2 115.77' 178 cf Porous Asphalt (Prismatic) Listed below (Recalc)

1,777 cf Overall x 10.0% Voids#3 115.44' 622 cf Choker Course (Prismatic) Listed below (Recalc)

1,777 cf Overall x 35.0% Voids#4 114.77' 1,263 cf Filter Course (Prismatic) Listed below (Recalc)

3,607 cf Overall x 35.0% Voids#5 114.52' 471 cf Pea Stone Course (Prismatic) Listed below (Recalc)


2,692 cf Overall x 35.0% Voids



116.10 10,475 612.8 0 0 10,475117.25 10,475 612.8 12,046 12,046 11,180

Elevation Surf.Area Inc.Store Cum.Store(feet) (sq-ft) (cubic-feet) (cubic-feet)

115.77 5,384 0 0116.10 5,384 1,777 1,777


115.44 5,384 0 0115.77 5,384 1,777 1,777


114.77 5,384 0 0115.44 5,384 3,607 3,607




114.52 5,384 0 0114.77 5,384 1,346 1,346


114.02 5,384 0 0114.52 5,384 2,692 2,692


#1 Primary 116.10' 20.0' long x 3.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 Coef. (English) 2.44 2.58 2.68 2.67 2.65 2.64 2.64 2.68 2.68 2.72 2.81 2.92 2.97 3.07 3.32

Primary OutFlow Max=0.11 cfs @ 18.19 hrs HW=116.12' (Free Discharge)1=Broad-Crested Rectangular Weir (Weir Controls 0.11 cfs @ 0.32 fps)

Pond 22P: Porous Asphalt w/ Check Dams

InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.28

0.26

0.24

0.22

0.2

0.18

0.16

0.14

0.12

0.1

0.08

0.06

0.04

0.02

0


Peak Elev=116.12'

Storage=3,657 cf

0.25 cfs

0.12 cfs



Summary for Pond 24P: Forebay/Stormwater Treatment Area 3


Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.01 hrs / 3Peak Elev= 115.19' @ 12.15 hrs Surf.Area= 1,854 sf Storage= 3,091 cf

Plug-Flow detention time= 126.7 min calculated for 0.245 af (85% of inflow)Center-of-Mass det. time= 57.2 min ( 856.5 - 799.3 )


#1 112.75' 3,696 cf Forebay/Stormwater Treatment Area 3 (Irregular) Listed below (Recalc)


112.75 0 0.0 0 0 0113.00 958 169.7 80 80 2,292114.00 1,320 187.9 1,134 1,214 2,840115.00 1,771 225.7 1,540 2,754 4,101115.50 2,000 232.0 942 3,696 4,357


#1 Primary 114.50' 18.0" Round Culvert X 2.00 L= 50.0' RCP, mitered to conform to fill, Ke= 0.700 Inlet / Outlet Invert= 114.50' / 114.25' S= 0.0050 '/' Cc= 0.900 n= 0.011 Concrete pipe, straight & clean, Flow Area= 1.77 sf




Pond 24P: Forebay/Stormwater Treatment Area 3

InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

4

3

2

1

0


Peak Elev=115.19'

Storage=3,091 cf

18.0"

Round Culvert x 2.00

n=0.011

L=50.0'

S=0.0050 '/'

4.04 cfs

3.44 cfs







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

7

6

5

4

3

2

1

0


6.80 cfs6.80 cfs














20.6 331 Total

Subcatchment PR-1:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

7

6

5

4

3

2

1

0

NOAA 24-hr D




Runoff Depth=1.85"

Flow Length=331'

Tc=20.6 min

CN=86

6.58 cfs











5.0 Direct Entry,

Subcatchment PR-2:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

5

4

3

2

1

0

NOAA 24-hr D




Runoff Depth=2.56"

Tc=5.0 min

CN=94

5.20 cfs












254.0 Direct Entry,

Subcatchment PR-3:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.36

0.34

0.32

0.3

0.28

0.26

0.24

0.22

0.2

0.18

0.16

0.14

0.12

0.1

0.08

0.06

0.04

0.02

0

NOAA 24-hr D




Runoff Depth=2.66"

Tc=254.0 min

CN=95

0.33 cfs











5.0 Direct Entry,

Subcatchment PR-4:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.38

0.36

0.34

0.32

0.3

0.28

0.26

0.24

0.22

0.2

0.18

0.16

0.14

0.12

0.1

0.08

0.06

0.04

0.02

0

NOAA 24-hr D




Runoff Depth=1.42"

Tc=5.0 min

CN=80

0.35 cfs











116.10 10,475 612.8 0 0 10,475117.25 10,475 612.8 12,046 12,046 11,180


115.00 2,389 278.9 0 0 2,389116.00 3,283 308.2 2,824 2,824 3,789


115.00 333 87.2 0 0 333116.00 631 108.9 474 474 686116.50 802 118.3 357 832 865







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.38

0.36

0.34

0.32

0.3

0.28

0.26

0.24

0.22

0.2

0.18

0.16

0.14

0.12

0.1

0.08

0.06

0.04

0.02

0


Peak Elev=115.69'

Storage=2,141 cf

12.0"

Round Culvert

n=0.011

L=26.0'

S=0.0085 '/'

0.35 cfs

0.14 cfs
















116.10 10,475 612.8 0 0 10,475117.25 10,475 612.8 12,046 12,046 11,180


115.77 5,384 0 0116.10 5,384 1,777 1,777


115.44 5,384 0 0115.77 5,384 1,777 1,777


114.77 5,384 0 0115.44 5,384 3,607 3,607




114.52 5,384 0 0114.77 5,384 1,346 1,346


114.02 5,384 0 0114.52 5,384 2,692 2,692





InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.36

0.34

0.32

0.3

0.28

0.26

0.24

0.22

0.2

0.18

0.16

0.14

0.12

0.1

0.08

0.06

0.04

0.02

0


Peak Elev=116.13'

Storage=3,768 cf

0.33 cfs

0.25 cfs










112.75 0 0.0 0 0 0113.00 958 169.7 80 80 2,292114.00 1,320 187.9 1,134 1,214 2,840115.00 1,771 225.7 1,540 2,754 4,101115.50 2,000 232.0 942 3,696 4,357







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

5

4

3

2

1

0


Peak Elev=115.30'

Storage=3,307 cf

18.0"


n=0.011

L=50.0'

S=0.0050 '/'

5.20 cfs

4.50 cfs







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

10

9

8

7

6

5

4

3

2

1

0


9.29 cfs9.29 cfs














20.6 331 Total

Subcatchment PR-1:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

13

12

11

10

9

8

7

6

5

4

3

2

1

0

NOAA 24-hr D




Runoff Depth=3.55"

Flow Length=331'

Tc=20.6 min

CN=86

12.44 cfs











5.0 Direct Entry,

Subcatchment PR-2:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

9

8

7

6

5

4

3

2

1

0

NOAA 24-hr D




Runoff Depth=4.40"

Tc=5.0 min

CN=94

8.62 cfs












254.0 Direct Entry,

Subcatchment PR-3:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.6

0.55

0.5

0.45

0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0

NOAA 24-hr D




Runoff Depth=4.51"

Tc=254.0 min

CN=95

0.54 cfs











5.0 Direct Entry,

Subcatchment PR-4:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.8

0.75

0.7

0.65

0.6

0.55

0.5

0.45

0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0

NOAA 24-hr D




Runoff Depth=2.97"

Tc=5.0 min

CN=80

0.72 cfs











116.10 10,475 612.8 0 0 10,475117.25 10,475 612.8 12,046 12,046 11,180


115.00 2,389 278.9 0 0 2,389116.00 3,283 308.2 2,824 2,824 3,789


115.00 333 87.2 0 0 333116.00 631 108.9 474 474 686116.50 802 118.3 357 832 865







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.8

0.75

0.7

0.65

0.6

0.55

0.5

0.45

0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0


Peak Elev=115.87'

Storage=2,803 cf

12.0"

Round Culvert

n=0.011

L=26.0'

S=0.0085 '/'

0.72 cfs

0.50 cfs
















116.10 10,475 612.8 0 0 10,475117.25 10,475 612.8 12,046 12,046 11,180


115.77 5,384 0 0116.10 5,384 1,777 1,777


115.44 5,384 0 0115.77 5,384 1,777 1,777


114.77 5,384 0 0115.44 5,384 3,607 3,607




114.52 5,384 0 0114.77 5,384 1,346 1,346


114.02 5,384 0 0114.52 5,384 2,692 2,692





InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.6

0.55

0.5

0.45

0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0


Peak Elev=116.15'

Storage=3,986 cf

0.54 cfs0.53 cfs










112.75 0 0.0 0 0 0113.00 958 169.7 80 80 2,292114.00 1,320 187.9 1,134 1,214 2,840115.00 1,771 225.7 1,540 2,754 4,101115.50 2,000 232.0 942 3,696 4,357







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

10

9

8

7

6

5

4

3

2

1

0


Peak Elev=115.79'

Storage=3,696 cf

18.0"


n=0.011

L=50.0'

S=0.0050 '/'

8.62 cfs

9.81 cfs







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0


17.50 cfs17.50 cfs














20.6 331 Total

Subcatchment PR-1:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

NOAA 24-hr D




Runoff Depth=4.66"

Flow Length=331'

Tc=20.6 min

CN=86

16.14 cfs











5.0 Direct Entry,

Subcatchment PR-2:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

12

11

10

9

8

7

6

5

4

3

2

1

0

NOAA 24-hr D




Runoff Depth=5.55"

Tc=5.0 min

CN=94

10.73 cfs












254.0 Direct Entry,

Subcatchment PR-3:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.75

0.7

0.65

0.6

0.55

0.5

0.45

0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0

NOAA 24-hr D




Runoff Depth=5.67"

Tc=254.0 min

CN=95

0.68 cfs











5.0 Direct Entry,

Subcatchment PR-4:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

1

0

NOAA 24-hr D




Runoff Depth=4.02"

Tc=5.0 min

CN=80

0.96 cfs











116.10 10,475 612.8 0 0 10,475117.25 10,475 612.8 12,046 12,046 11,180


115.00 2,389 278.9 0 0 2,389116.00 3,283 308.2 2,824 2,824 3,789


115.00 333 87.2 0 0 333116.00 631 108.9 474 474 686116.50 802 118.3 357 832 865







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

1

0


Peak Elev=115.94'

Storage=3,058 cf

12.0"

Round Culvert

n=0.011

L=26.0'

S=0.0085 '/'

0.96 cfs

0.67 cfs






Plug-Flow detention time= 200.1 min calculated for 0.275 af (78% of inflow)Center-of-Mass det. time= 99.4 min ( 1,095.3 - 995.9 )










116.10 10,475 612.8 0 0 10,475117.25 10,475 612.8 12,046 12,046 11,180


115.77 5,384 0 0116.10 5,384 1,777 1,777


115.44 5,384 0 0115.77 5,384 1,777 1,777


114.77 5,384 0 0115.44 5,384 3,607 3,607




114.52 5,384 0 0114.77 5,384 1,346 1,346


114.02 5,384 0 0114.52 5,384 2,692 2,692





InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.75

0.7

0.65

0.6

0.55

0.5

0.45

0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0


Peak Elev=116.16'

Storage=4,073 cf

0.68 cfs0.68 cfs










112.75 0 0.0 0 0 0113.00 958 169.7 80 80 2,292114.00 1,320 187.9 1,134 1,214 2,840115.00 1,771 225.7 1,540 2,754 4,101115.50 2,000 232.0 942 3,696 4,357







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

12

11

10

9

8

7

6

5

4

3

2

1

0


Peak Elev=115.87'

Storage=3,696 cf

18.0"


n=0.011

L=50.0'

S=0.0050 '/'

10.73 cfs10.70 cfs







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

23

22

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0


20.86 cfs20.86 cfs














20.6 331 Total

Subcatchment PR-1:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

24

23

22

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

NOAA 24-hr D




Runoff Depth=6.39"

Flow Length=331'

Tc=20.6 min

CN=86

21.81 cfs











5.0 Direct Entry,

Subcatchment PR-2:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

NOAA 24-hr D




Runoff Depth=7.34"

Tc=5.0 min

CN=94

13.96 cfs












254.0 Direct Entry,

Subcatchment PR-3:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.95

0.9

0.85

0.8

0.75

0.7

0.65

0.6

0.55

0.5

0.45

0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0

NOAA 24-hr D




Runoff Depth=7.46"

Tc=254.0 min

CN=95

0.88 cfs











5.0 Direct Entry,

Subcatchment PR-4:

Runoff

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

1

0

NOAA 24-hr D




Runoff Depth=5.68"

Tc=5.0 min

CN=80

1.33 cfs











116.10 10,475 612.8 0 0 10,475117.25 10,475 612.8 12,046 12,046 11,180


115.00 2,389 278.9 0 0 2,389116.00 3,283 308.2 2,824 2,824 3,789


115.00 333 87.2 0 0 333116.00 631 108.9 474 474 686116.50 802 118.3 357 832 865







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

1

0


Peak Elev=116.03'

Storage=3,316 cf

12.0"

Round Culvert

n=0.011

L=26.0'

S=0.0085 '/'

1.33 cfs

0.92 cfs






Plug-Flow detention time= 168.5 min calculated for 0.388 af (83% of inflow)Center-of-Mass det. time= 84.7 min ( 1,074.3 - 989.6 )










116.10 10,475 612.8 0 0 10,475117.25 10,475 612.8 12,046 12,046 11,180


115.77 5,384 0 0116.10 5,384 1,777 1,777


115.44 5,384 0 0115.77 5,384 1,777 1,777


114.77 5,384 0 0115.44 5,384 3,607 3,607




114.52 5,384 0 0114.77 5,384 1,346 1,346


114.02 5,384 0 0114.52 5,384 2,692 2,692





InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

0.95

0.9

0.85

0.8

0.75

0.7

0.65

0.6

0.55

0.5

0.45

0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0


Peak Elev=116.17'

Storage=4,186 cf

0.88 cfs0.88 cfs










112.75 0 0.0 0 0 0113.00 958 169.7 80 80 2,292114.00 1,320 187.9 1,134 1,214 2,840115.00 1,771 225.7 1,540 2,754 4,101115.50 2,000 232.0 942 3,696 4,357







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0


Peak Elev=116.24'

Storage=3,696 cf

18.0"


n=0.011

L=50.0'

S=0.0050 '/'

13.96 cfs

14.62 cfs







InflowPrimary

Hydrograph

Time (hours)727068666462605856545250484644424038363432302826242220181614121086420

Flo

w

(cfs

)

30

28

26

24

22

20

18

16

14

12

10

8

6

4

2

0


28.48 cfs28.48 cfs


APPENDIX D

Long-Term Pollution Prevention and Stormwater Operation and Maintenance Plan

LONG-TERM POLLUTION PREVENTION PLAN AND STORMWATER OPERATION AND MAINTENANCE PLAN

91 Hartwell Avenue, Lexington, MA

TABLE OF CONTENTS

1.0 INTRODUCTION ............................................................................................................. 1

2.0 LONG-TERM POLLUTION PREVENTION PLAN ........................................................... 2

2.1 Storage of Hazardous Materials ........................................................................................................ 2

2.2 Storage of Waste Products ................................................................................................................ 2

2.3 Spill Prevention and Response ......................................................................................................... 2

2.4 Minimize Soil Erosion ........................................................................................................................ 2

2.5 Vehicle Washing ................................................................................................................................ 3

2.6 Maintenance of Lawns, Gardens, and other Landscaped Areas ...................................................... 3

2.7 Management of Deicing Chemicals and Snow .................................................................................. 3

2.8 Coordination with other Permits and Requirements .......................................................................... 4

3.0 STORMWATER MANAGEMENT SYSTEM OPERATION AND MAINTENANCE PLAN 5

3.1 Introduction ........................................................................................................................................ 5

3.2 Stormwater Operation and Maintenance Requirements ................................................................... 5

Deep Sump and Hooded Catch Basins ...................................................................................................................... 5 Porous Pavement ...................................................................................................................................................... 6 Detention Basin ......................................................................................................................................................... 6 Level Spreaders ......................................................................................................................................................... 7 Stormwater Outfalls .................................................................................................................................................. 7 Oil/Water Separators ................................................................................................................................................ 7

3.3 Street Sweeping ................................................................................................................................ 7

3.4 Repair of the Stormwater Management System ............................................................................... 7

3.5 Reporting ........................................................................................................................................... 7

STORMWATER MANAGEMENT SYSTEM INSPECTION FORM ............................................. 8

FIGURES Figure 1 – Best Management Practices Map Figure 2 – Snow Storage Map

91 Hartwell Avenue, Lexington, MA Notice of Intent Long Term Pollution Prevention Plan & Stormwater October 25, 2019 Operation and Maintenance Plan

Page | 1

1.0 INTRODUCTION

The purpose of this document is to specify the pollution prevention measures and stormwater management system operation and maintenance for the 91 Hartwell Avenue site. The Responsible Party indicated below shall implement the management practices outlined in this document and proactively conduct operations at the project site in an environmentally responsible manner. Compliance with this Manual does not in any way dismiss the responsible party, owner, property manager, or occupants from compliance with other applicable federal, state or local laws. Responsible Party: LPC Northeast, LLC 53 State Street, 8th Floor

Boston, MA 02109 This Document has been prepared in compliance with Standards 4 and 9 of the 2008 Massachusetts Department of Environmental Protection (MassDEP) Stormwater Management Standards, which state: Standard 4: The Long Term Pollution Prevention Plan shall include the proper procedures for the following:

• Good housekeeping

• Storing materials and waste products inside or under cover

• Vehicle washing

• Routine inspections of stormwater best management practices

• Spill prevention and response

• Maintenance of lawns, gardens, and other landscaped areas

• Storage and use of fertilizers, herbicides, and pesticides

• Pet waste management

• Operation and management of septic systems

• Proper management of deicing chemicals and snow Standard 9: The Long-Term Operation and Maintenance Plan shall at a minimum include:

• Stormwater management system(s) owner(s)

• The party or parties responsible for operation and maintenance, including how future property owners shall be notified of the presence of the stormwater management system and the requirement for operation and maintenance

• The routine and non-routine maintenance tasks to be undertaken after construction is complete and a schedule for implementing those tasks

• A plan that is drawn to scale and shows the location of all stormwater BMPs in each treatment train along with the discharge point

• A description and delineation of public safety features

• An estimated operations and maintenance budget


Page | 2

2.0 LONG-TERM POLLUTION PREVENTION PLAN

The Responsible Party shall implement the following good housekeeping procedures at the project site to reduce the possibility of accidental releases and to reduce safety hazards. 2.1 Storage of Hazardous Materials

To prevent leaks and spills, keep hazardous materials and waste products under cover or inside. Use drip pans or spill containment systems to prevent chemicals from entering the drainage system. Inspect storage areas for materials and waste products at least once per year to determine amount and type of the material on site, and if the material requires disposal. Securely store liquid petroleum products and other liquid chemicals in federally- and state-approved containers. Restrict access to maintenance personnel and administrators. 2.2 Storage of Waste Products

Collect and store all waste materials in securely lidded dumpster(s) or other secure containers as applicable to the material. Keep dumpster lids closed and the areas around them clean. Do not fill the dumpsters with liquid waste or hose them out. Sweep areas around the dumpster regularly and put the debris in the garbage, instead of sweeping or hosing it into the parking lot. Legally dispose of collected waste on a regular basis. Segregate liquid wastes, including motor oil, antifreeze, solvents, and lubricants, from solid waste and recycle through hazardous waste disposal companies, whenever possible. Separate oil filters, batteries, tires, and metal filings from grinding and polishing metal parts from common trash items and recycle. These items are not trash and are illegal to dump. Contact a hazardous waste hauler for proper disposal to a hazardous waste collection center. 2.3 Spill Prevention and Response

Implement spill response procedures for releases of significant materials such as fuels, oils, or chemical materials onto the ground or other area that could reasonably be expected to discharge to surface or groundwater.

• For minor spills, keep fifty (50) gallon spill control kits and Speedy Dry at all shop and work areas.

• Immediately contact applicable Federal, State, and local agencies for reportable quantities as required by law.

• Immediately perform applicable containment and cleanup procedures following a spill release.

• Promptly remove and dispose of all material collected during the response in accordance with Federal, State and local requirements. A licensed emergency response contractor may be required to assist in cleanup of releases depending on the amount of the release, and the ability of the Contractor to perform the required response.

• Reportable quantities of chemicals, fuels, or oils are established under the Clean Water Act and enforced through Massachusetts Department of Environmental Protection (DEP).

2.4 Minimize Soil Erosion

Soil erosion facilitates mechanical transport of nutrients, pathogens, and organic matter to surface water bodies. Repair all areas where erosion is occurring throughout the project site. Stabilize bare soil with riprap, seed, mulch, or vegetation.


Page | 3

2.5 Vehicle Washing

Vehicle washing shall not occur on the property. 2.6 Maintenance of Lawns, Gardens, and other Landscaped Areas

Pesticides and fertilizers shall not be used in the landscaped areas associated with the project site and shall not be stored on-site. Dumping of lawn wastes, brush or leaves or other materials or debris is not permitted in any Resource Area. Grass clippings, pruned branches and any other landscaped waste should be disposed of or composted in an appropriate location outside of wetland resource areas and buffer zones. No irrigation shall be used in the landscaped areas for this project. 2.7 Management of Deicing Chemicals and Snow

The qualified contractor selected for snow plowing and deicing shall be made fully aware of the requirements of this section. There will be no usage of salt-based deicing chemicals within buffer areas of the wetland resources areas. Deicing chemicals shall not be stored outside on the project site; they shall be stored in a locked room inside of a building and may be used on exterior walkways located outside of wetland buffer areas. During typical snow plowing operations, snow shall be pushed to the designated snow removal areas noted on the Snow Storage Map (Figure 2). Snow shall not be stockpiled in wetland resource areas or the 100-foot Buffer Zone, catch basins, or constructed wetlands. In severe conditions where snow cannot be stockpiled on site, the snow shall be removed from the site and properly disposed of in accordance with DEP Guideline BRP601-01. Use of sand is permitted only for impervious roadways and parking areas. If sand is applied, the snow plowed from impervious areas shall not be stored on porous asphalt. Porous asphalt areas are proposed throughout the site, as indicated on the Best Management Practices Map (Figure 1). These areas will be delineated on-site using pavement markings. Porous asphalt performs well in cold climates and can reduce meltwater runoff during the snowmelt period; however there are specific winter management techniques that must be followed for porous asphalt systems. The porous asphalt areas shall be maintained during snow events as provided below:

• Apply anti-icing treatments only when absolutely necessary (in extreme events). It is not anticipated that deicing chemicals will be required for typical winter events.

• Plow as needed after storm events. Avoid scarifying the porous asphalt surface. Special plow blades should be used whenever possible. Raised blade is not recommended.

• Apply the minimum amount of deicing agents during and after storms required to control compact snow and ice that are not removed by plowing.

• Do not apply sand in porous asphalt areas “No Sanding” signs shall be posted before the first snowfall and maintenance and snow removal contractors shall be made aware of this requirement.

Before winter begins, the property owner and the contractor shall review snow plowing, deicing, and stockpiling procedures. Areas designated for stockpiling should be cleaned of any debris. Street and parking lot sweeping should be followed in accordance with the Operation and Maintenance Plan.


Page | 4

2.8 Coordination with other Permits and Requirements

Certain conditions of other approvals affecting the long term management of the property shall be considered part of this Long Term Pollution Prevention Plan. The Owner shall become familiar with those documents and comply with the guidelines set forth in those documents.


Page | 5

3.0 STORMWATER MANAGEMENT SYSTEM OPERATION AND MAINTENANCE PLAN

3.1 Introduction

This Operation and Maintenance Plan (O&M Plan) for 91 Hartwell Avenue site is required under Standard 9 of the 2008 MassDEP Stormwater Handbook to provide best management practices for implementing maintenance activities for the stormwater management system in a manner that minimizes impacts to wetland resource areas. The Owner shall implement this O&M Plan and proactively conduct operations at the site in an environmentally responsible manner. Compliance with this O&M Plan does not in any way dismiss the Owner from compliance with other applicable Federal, State or local laws. Routine maintenance during construction and post-development phases of the project, as defined in the Operation and Maintenance Plan, shall be permitted without amendment to the Order of Conditions. A continuing condition in the Certificate of Compliance shall ensure that maintenance can be performed without triggering further filings under the Wetlands Protection Act. All stormwater best management practices (BMPs) shall be operated and maintained in accordance with the design plans and the Operation and Maintenance Plan approved by the issuing authority. The Owner shall:

a. Maintain an operation and maintenance log for the last three years, including inspections, repairs, replacement and disposal (for disposal the log shall indicate the type of material and the disposal location). This is a rolling log in which the responsible party records all operation and maintenance activities for the past three years.

b. Make this log available to MassDEP and the Conservation Commissions upon request; and

c. Allow members and agents of the MassDEP and the Conservation Commissions to enter and

inspect the premises to evaluate and ensure that the Owner complies with the Operation and Maintenance requirements for each BMP.

3.2 Stormwater Operation and Maintenance Requirements

Inspect and maintain the stormwater management system as directed below. Refer to the Best Management Practices Map (Figure 1) for the location of each component of the system. Repairs to any component of the system shall be made as soon as possible to prevent any potential pollutants (including silt) from entering the resource areas. Deep Sump and Hooded Catch Basins

Inspect or clean catch basins four times per year and at the end of foliage and snow-removal seasons. Other inspection and maintenance requirements include:

• Remove organic material, sediment and hydrocarbons four times per year or whenever the depth of deposits is greater than or equal to one half the depth from the bottom of the invert of the lowest pipe in the basin.

• Always clean out catch basins after street sweeping. If any evidence of hydrocarbons is found during inspection, immediately remove the material using absorbent pads or other suitable measures and dispose of legally. Remove other accumulated debris as necessary.

• If handling runoff from land uses with higher potential pollutant loads or discharging runoff near or to a critical area, more frequent cleaning may be necessary.


Page | 6

• Transport and disposal of accumulated sediment off-site shall be in accordance with applicable local, state and federal guidelines and regulations.

Porous Pavement

Porous pavement areas are proposed throughout the site, as indicated on the Best Management Practices Map (Figure 1). These areas will be delineated on-site using pavement markings. Frequent cleaning and maintenance of the porous pavement surface is critical to prevent clogging. Frequent vacuum sweeping along with jet washing of porous pavement is required. No winter sanding shall be conducted on the porous surface. For proper maintenance:

• Post signs identifying porous pavement areas.

• Minimize salt use during winter months.

• No winter sanding is allowed.

• Keep landscaped areas well maintained to prevent soil from being transported onto the pavement.

• Regularly monitor the porous pavement surface to make sure that it drains properly after storm events. Inspect surface annually for deterioration or spalling.

• At a minimum, the porous pavement shall be cleaned after the winter season and every three months thereafter. This requirement may be adjusted as needed, based on regular visual inspections of the porous pavement surface.

• For porous asphalts and concretes, clean the surface using power washer to dislodge trapped particles and then vacuum sweep the area.

• For paving stones, add joint material to replace material that has been transported. Reseed grass pavers to fill in bare spots.

• Never reseal or repave with impermeable materials.

• Once per year, the infiltrative capacity of the porous pavement should be tested by running a hose over each porous pavement area for 30 minutes.

• Sections of damaged porous asphalt (rutting, etc.) can be repaired by heating and rerolling the asphalt.

• When infiltrative capacity of porous pavement is reduced to less than the design rate, the porous pavement shall be replaced by milling to the choker course.

• Attach rollers to the bottoms of snowplows to prevent them from catching on the edges of grass paveres and some paving stones.

Detention Basin

Inspect the detention basin at least once per year to ensure that the basin is operating as intended. Inspect the detention basin during and after major storms to determine if the basin is meeting the expected detention times.

• Examine the outlet structure for evidence of clogging or outflow release velocities that are greater than design flow.

o Potential problems that should be checked include: subsidence, erosion, cracking or tree growth on the embankment; damage to the emergency spillway; sediment accumulation around the outlet; inadequacy of the inlet/outlet channel erosion control measures; changes in the condition of the pilot channel; and erosion within the basin and banks. Make any necessary repairs immediately.

• During inspections, note any changes to the extended dry detention basin or the contributing watershed, because these could affect basin performance.

• Inspect basins to ensure they are operating as designed at least once per year


Page | 7

• Mow the upper-stage, side slopes, embankment, and emergency spillway at least twice per year. Also remove trash and debris at this time.

• Check the sediment forebay for accumulated sediment, trash and debris and remove it at least twice per year.

• Remove sediment from the extended dry detention basin as necessary, but at least once every 5 years. Providing an on-site sediment disposal area will reduce the overall sediment removal costs.

Level Spreaders

Inspect level spreaders regularly, especially after major storm events (rainfall totals greater than 2.5 inches in 24 hours). Repair any erosion or low spots in the level spreader. Stormwater Outfalls

Inspect flared end sections and associated riprap spillways at least once per year and after major storm events (rainfall totals greater than 2.5 inches in 24 hours) to ensure that the stability of the outlet area is maintained. Keep the outfall area clear of debris such as trash, branches, and sediment. Make repairs immediately if riprap displacement or downstream channel scour is observed. Oil/Water Separators

At a minimum, inspect oil/water separators monthly, and clean them out at least twice per year. In the event of a hazardous waste spill, the oil/water separator should be cleaned immediately. Cleaning involves the removal of accumulated oil and grease and sediment using a vacuum truck. Polluted water or sediments removed from the oil/water separators shall be disposed of in accordance with all applicable local, state, and federal laws and regulations, including M.G.L.c. 21C and 310 CMR 30.00.

3.3 Street Sweeping

Perform street sweeping at least twice per year, whenever there is significant debris present on roads and parking lots. Street sweeping shall occur in the spring and fall. Sweepings must be handled and disposed of properly according to the Lexington Conservation Commissions. 3.4 Repair of the Stormwater Management System

The stormwater management system shall be maintained. The repair of any component of the system shall be made as soon as possible to prevent any potential pollutants including silt from entering the resource areas or the existing closed drainage system. 3.5 Reporting

The Owner shall maintain a record of drainage system inspections and maintenance (per this Plan) and submit a yearly report to the Lexington Conservation Commissions.

Page | 8

STORMWATER MANAGEMENT SYSTEM INSPECTION FORM

91 Hartwell Avenue Inspected by:____________ Lexington, MA Date:____________

Component Status/Inspection Action Taken

Deep Sump Catch Basins, Area Drains and Drain Manholes

Detention Basin

Oil/Water Separator

Porous Asphalt

Stormwater Outfalls & Level Spreaders

General site conditions – evidence of erosion, etc.

SUBMIT COPIES OF STORMWATER MANAGEMENT SYSTEM INSPECTION FORM TO THE

LEXINGTON CONSERVATION COMMISSIONS WITH THE YEARLY REPORT.

Page | 1

INSPECTION CHECKLIST (POROUS PAVEMENT)

Location:

Date: Time:

Date Since Last Rain Event:

Inspector:

Site Conditions:

Inspection Items Satisfactory (S) or

Unsatisfactory (U)

Comments/Corrective Action

Salt/Deicing

Use salt only for ice management S U

Piles of accumulated salt removed in spring S U

Debris Cleanup (2 times a year minimum, Spring & Fall)

Clean porous pavement to remove sediment and organic debris on the pavement surface via vacuum street sweeper

S U

Adjacent non porous pavement vacuumed S U

Clean catch basins (if applicable) S U

Controlling Run-On (2-4 times a year)

Adjacent vegetated areas show no signs of erosion and run-on to porous pavement

S U

Catch Basin Inspection (if applicable)(1 time a year, After large storm events)

No evidence of blockage S U

Good condition, no need for cleaning/repair S U

Poorly Drained Pavement (2-4 times a year)

Pavement has been pressure washed and vacuumed

S U

Pavement Condition (2-4 times a year, Spring & Fall)

No evidence of deterioration S U

No cuts from utilities visible S U

No evidence of improper design load applied S U

Signage/Stockpiling (As Needed)

Proper signage posted indicating usage for traffic load

S U

No stockpiling of materials and no seal coating

S U

Corrective Action Needed Due Date

1.

2.

3.

4.

Page | 2

INSPECTION CHECKLIST (DEEP SUMP AND HOODED CATCH BASINS)

Location:

Date: Time:


Inspector:

Site Conditions:


Unsatisfactory (U)


Inspections (2 times a year minimum, Spring & Fall)

Visual evidence of trash, debris or dumping S U

Dead animals or vegetation that could generate odors or gases and could cause complaints

S U

Evidence of oil, gasoline, contaminants, or other pollutants

S U

Condition of basin. Is there a safety, function, or design problem (need for repair)

S U

Vegetation blocking more than 10% of the basin opening (lawn areas)

S U

Trash and debris blocking more than 20% of grate surface inlet capacity

S U

Missing grate, missing or broken grate members

S U

Grout fillet is separated or cracked wider than ½ inch and longer than 1 foot at the joint of outlet pipe; evidence of soil entering through cracks

S U

Trash or debris in the basin exceeds 50% of the sump depth from the bottom of basin to invert of the outlet pipe; less than 6 inches clearance from the debris surface to the invert of the outlet pipe

S U

Sediment in the basin exceeds 50% of the sump depth from the bottom of basin to invert of the outlet pipe; less than 6 inches clearance from the debris surface to the invert of the outlet pipe

S U

Trash or debris blocking outlet pipe S U

Debris Cleanup (2 times a year minimum, Spring & Fall)

Remove and legally dispose sediment, trash, and debris

S U

Remove and legally dispose contaminants or pollutants

S U

Repair catch basin (as necessary) S U

Replace catch basin castings (as necessary)

Controlling Run-On (2-4 times a year)

Adjacent vegetated areas show no signs of erosion and run-on to catch basin

S U


1.

2.

3.

4.

Page | 3

INSPECTION CHECKLIST (DETENTION BASINS)

Location:

Date: Time:


Inspector:

Site Conditions:


Unsatisfactory (U)


Inspections (During and after major storm events, 1 time a year minimum)


Examine the outlet structure for evidence of clogging or outflow release velocities that are greater than design flow.

S U

Condition of basin. Is there a safety, function, or design problem (need for repair)

S U

Identify areas of sediment accumulation, differential settlement, cracking, and erosion within the basin

S U

Note any changes to the extended dry detention basin or the contributing watershed, because these could affect basin performance

S U

Examine the health of the vegetation within the basin and on the embankments

S U

Debris Cleanup (During and after major storm events, 1 time a year minimum)


S U


S U

Mow the upper-stage, side slopes, embankment, and emergency spillway at least twice per year.

S U

Remove sediment from the extended dry detention basin as necessary (at least once every 5 years)

S U


1.

2.

3.

4.

Page | 4

INSPECTION CHECKLIST (LEVEL SPREADERS)

Location:

Date: Time:


Inspector:

Site Conditions:


Unsatisfactory (U)


Inspections (2 times a year, Spring & Fall and after rain events larger than 2.5”)

Repair any erosion or low spots in the level spreader

S U


Maintenance (2 times a year, Spring & Fall and after rain events larger than 2.5”)


S U


S U


1.

2.

3.

4.

Page | 5

INSPECTION CHECKLIST (STORMWATER OUTFALLS)

Location:

Date: Time:


Inspector:

Site Conditions:


Unsatisfactory (U)


Inspections (1 time a year minimum, and after rain events larger than 2.5”)


Condition of structure. Is there a safety, function, or design problem (need for repair)

S U

Inspect flared end sections and associated riprap to ensure that the stability of the outlet area is maintained

S U

Trash or debris blocking inlet/outlet pipe S U

Maintenance (1 time a year minimum, and after rain events larger than 2.5”)


S U


S U

Make repairs immediately if riprap displacement or downstream channel scour is observed

S U


1.

2.

3.

Page | 6

INSPECTION CHECKLIST (OIL/WATER SEPERATORS)

Location:

Date: Time:


Inspector:

Site Conditions:


Unsatisfactory (U)


Inspections (Once per month minimum)


Debris Cleanup (Once per month minimum)


S U

Remove and dispose of accumulated oil and grease and sediment using a vacuum truck

S U


S U


S U

Cleaning (2 times a year minimum, Spring & Fall)

Clean oil/water separators out at least twice per year. In the event of a hazardous waste spill, the oil/water separator should be cleaned immediately.

S U


1.

2.

3.

4.


APPENDIX E

Soil Investigations NRCS Soil Maps and Descriptions Preliminary Design Geotechnical Memo

United StatesDepartment ofAgriculture

A product of the NationalCooperative Soil Survey,a joint effort of the UnitedStates Department ofAgriculture and otherFederal agencies, Stateagencies including theAgricultural ExperimentStations, and localparticipants

Custom Soil Resource Report forMiddlesex County, MassachusettsNatural

ResourcesConservationService

April 11, 2019

PrefaceSoil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment.

Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations.

Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?cid=nrcs142p2_053951).

Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations.

The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey.

Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information.

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require

2

http://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/health/

http://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/health/

https://offices.sc.egov.usda.gov/locator/app?agency=nrcs

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?cid=nrcs142p2_053951

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?cid=nrcs142p2_053951

alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer.

3

ContentsPreface.................................................................................................................... 2How Soil Surveys Are Made..................................................................................5Soil Map.................................................................................................................. 8

Soil Map................................................................................................................9Legend................................................................................................................10Map Unit Legend................................................................................................ 11Map Unit Descriptions.........................................................................................11

Middlesex County, Massachusetts..................................................................1332B—Wareham loamy fine sand, 0 to 5 percent slopes............................. 1336A—Saco mucky silt loam, 0 to 1 percent slopes..................................... 1452A—Freetown muck, 0 to 1 percent slopes.............................................. 16603—Urban land, wet substratum...............................................................17653—Udorthents, sandy..............................................................................18655—Udorthents, wet substratum...............................................................19656—Udorthents-Urban land complex........................................................ 20

References............................................................................................................22

4

How Soil Surveys Are MadeSoil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity.

Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA.

The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape.

Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries.

Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil

5

scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research.

The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas.

Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil-landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape.

Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties.

While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil.

Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date.

After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and

Custom Soil Resource Report

6

identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately.


7

Soil MapThe soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit.

8

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10

Map Unit Legend

Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI

32B Wareham loamy fine sand, 0 to 5 percent slopes

5.1 10.4%

36A Saco mucky silt loam, 0 to 1 percent slopes

0.0 0.0%

52A Freetown muck, 0 to 1 percent slopes

12.0 24.2%

603 Urban land, wet substratum 19.5 39.4%

653 Udorthents, sandy 0.9 1.7%

655 Udorthents, wet substratum 1.1 2.2%

656 Udorthents-Urban land complex 10.9 22.0%

Totals for Area of Interest 49.4 100.0%

Map Unit DescriptionsThe map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit.

A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils.

Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it


11

was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape.

The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas.

An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities.

Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement.

Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.

Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups.

A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example.

An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example.

An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.

Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example.


12

Middlesex County, Massachusetts

32B—Wareham loamy fine sand, 0 to 5 percent slopes

Map Unit SettingNational map unit symbol: vqndElevation: 0 to 2,100 feetMean annual precipitation: 45 to 54 inchesMean annual air temperature: 43 to 54 degrees FFrost-free period: 145 to 240 daysFarmland classification: Not prime farmland

Map Unit CompositionWareham and similar soils: 80 percentMinor components: 20 percentEstimates are based on observations, descriptions, and transects of the mapunit.

Description of Wareham

SettingLandform: Depressions, deltas, terracesLandform position (two-dimensional): ToeslopeLandform position (three-dimensional): Tread, dipDown-slope shape: ConcaveAcross-slope shape: ConcaveParent material: Loose sandy glaciofluvial deposits

Typical profileH1 - 0 to 10 inches: loamy fine sandH2 - 10 to 24 inches: loamy sandH3 - 24 to 34 inches: stratified sand to fine sandH4 - 34 to 65 inches: stratified coarse sand to sand

Properties and qualitiesSlope: 0 to 5 percentDepth to restrictive feature: More than 80 inchesNatural drainage class: Poorly drainedCapacity of the most limiting layer to transmit water (Ksat): High to very high (6.00

to 20.00 in/hr)Depth to water table: About 6 to 18 inchesFrequency of flooding: NoneFrequency of ponding: NoneAvailable water storage in profile: Low (about 4.5 inches)

Interpretive groupsLand capability classification (irrigated): None specifiedLand capability classification (nonirrigated): 4wHydrologic Soil Group: A/DHydric soil rating: Yes

Minor Components

SudburyPercent of map unit: 10 percentLandform: Terraces, plainsLandform position (two-dimensional): Footslope


13

Landform position (three-dimensional): Tread, dipDown-slope shape: LinearAcross-slope shape: ConcaveHydric soil rating: No

ScarboroPercent of map unit: 5 percentLandform: TerracesLandform position (two-dimensional): ToeslopeLandform position (three-dimensional): TreadDown-slope shape: LinearAcross-slope shape: LinearHydric soil rating: Yes

DeerfieldPercent of map unit: 5 percentLandform: Stream terraces, depressions, deltasLandform position (two-dimensional): ToeslopeLandform position (three-dimensional): Tread, dipDown-slope shape: ConcaveAcross-slope shape: ConcaveHydric soil rating: No

36A—Saco mucky silt loam, 0 to 1 percent slopes

Map Unit SettingNational map unit symbol: vzt3Elevation: 50 to 500 feetMean annual precipitation: 45 to 54 inchesMean annual air temperature: 43 to 54 degrees FFrost-free period: 145 to 240 daysFarmland classification: Not prime farmland

Map Unit CompositionSaco and similar soils: 80 percentMinor components: 20 percentEstimates are based on observations, descriptions, and transects of the mapunit.

Description of Saco

SettingLandform: Alluvial flats, terracesLandform position (two-dimensional): ToeslopeLandform position (three-dimensional): Tread, dipDown-slope shape: LinearAcross-slope shape: ConcaveParent material: Silty alluvium

Typical profileH1 - 0 to 13 inches: mucky silt loamH2 - 13 to 30 inches: silt loam


14

H3 - 30 to 45 inches: silt loamH4 - 45 to 65 inches: loamy sand

Properties and qualitiesSlope: 0 to 1 percentDepth to restrictive feature: More than 80 inchesNatural drainage class: Very poorly drainedCapacity of the most limiting layer to transmit water (Ksat): Moderately high to

high (0.60 to 2.00 in/hr)Depth to water table: About 0 to 6 inchesFrequency of flooding: FrequentFrequency of ponding: NoneAvailable water storage in profile: High (about 11.5 inches)

Interpretive groupsLand capability classification (irrigated): None specifiedLand capability classification (nonirrigated): 6wHydrologic Soil Group: B/DHydric soil rating: Yes

Minor Components

FreetownPercent of map unit: 8 percentLandform: Depressions, bogsLandform position (two-dimensional): ToeslopeLandform position (three-dimensional): DipDown-slope shape: ConcaveAcross-slope shape: ConcaveHydric soil rating: Yes

SwanseaPercent of map unit: 8 percentLandform: Bogs, depressionsLandform position (two-dimensional): ToeslopeLandform position (three-dimensional): DipDown-slope shape: ConcaveAcross-slope shape: ConcaveHydric soil rating: Yes

LimerickPercent of map unit: 4 percentLandform: Alluvial flats, terracesLandform position (two-dimensional): ToeslopeLandform position (three-dimensional): Tread, dipDown-slope shape: LinearAcross-slope shape: ConcaveHydric soil rating: Yes


15

52A—Freetown muck, 0 to 1 percent slopes

Map Unit SettingNational map unit symbol: 2t2q9Elevation: 0 to 1,110 feetMean annual precipitation: 36 to 71 inchesMean annual air temperature: 39 to 55 degrees FFrost-free period: 140 to 240 daysFarmland classification: Farmland of unique importance

Map Unit CompositionFreetown and similar soils: 85 percentMinor components: 15 percentEstimates are based on observations, descriptions, and transects of the mapunit.

Description of Freetown

SettingLandform: Swamps, depressions, depressions, bogs, marshes, kettlesLandform position (two-dimensional): ToeslopeLandform position (three-dimensional): Tread, dipDown-slope shape: ConcaveAcross-slope shape: ConcaveParent material: Highly decomposed organic material

Typical profileOe - 0 to 2 inches: mucky peatOa - 2 to 79 inches: muck

Properties and qualitiesSlope: 0 to 1 percentPercent of area covered with surface fragments: 0.0 percentDepth to restrictive feature: More than 80 inchesNatural drainage class: Very poorly drainedRunoff class: NegligibleCapacity of the most limiting layer to transmit water (Ksat): Moderately low to high

(0.14 to 14.17 in/hr)Depth to water table: About 0 to 6 inchesFrequency of flooding: RareFrequency of ponding: FrequentAvailable water storage in profile: Very high (about 19.2 inches)

Interpretive groupsLand capability classification (irrigated): None specifiedLand capability classification (nonirrigated): 5wHydrologic Soil Group: B/DHydric soil rating: Yes


16

Minor Components

ScarboroPercent of map unit: 5 percentLandform: Drainageways, depressionsLandform position (two-dimensional): ToeslopeLandform position (three-dimensional): Base slope, tread, dipDown-slope shape: ConcaveAcross-slope shape: ConcaveHydric soil rating: Yes

SwanseaPercent of map unit: 5 percentLandform: Bogs, kettles, depressions, depressions, marshes, swampsLandform position (two-dimensional): ToeslopeLandform position (three-dimensional): Tread, dipDown-slope shape: ConcaveAcross-slope shape: ConcaveHydric soil rating: Yes

WhitmanPercent of map unit: 5 percentLandform: Depressions, drainagewaysLandform position (two-dimensional): ToeslopeLandform position (three-dimensional): Base slopeDown-slope shape: ConcaveAcross-slope shape: ConcaveHydric soil rating: Yes

603—Urban land, wet substratum

Map Unit SettingNational map unit symbol: 9951Mean annual precipitation: 32 to 50 inchesMean annual air temperature: 45 to 50 degrees FFrost-free period: 110 to 200 daysFarmland classification: Not prime farmland

Map Unit CompositionUrban land: 85 percentMinor components: 15 percentEstimates are based on observations, descriptions, and transects of the mapunit.

Description of Urban Land

SettingLandform position (two-dimensional): FootslopeLandform position (three-dimensional): Base slopeDown-slope shape: LinearAcross-slope shape: Linear


17

Parent material: Excavated and filled land over alluvium and/or marine deposits

Minor Components

Udorthents, loamyPercent of map unit: 10 percentHydric soil rating: No

Rock outcropPercent of map unit: 5 percentLandform: LedgesLandform position (two-dimensional): SummitLandform position (three-dimensional): Head slopeDown-slope shape: ConcaveAcross-slope shape: Concave

653—Udorthents, sandy

Map Unit SettingNational map unit symbol: vr1kElevation: 0 to 3,000 feetMean annual precipitation: 32 to 50 inchesMean annual air temperature: 45 to 50 degrees FFrost-free period: 110 to 200 daysFarmland classification: Not prime farmland

Map Unit CompositionUdorthents, sandy, and similar soils: 85 percentMinor components: 15 percentEstimates are based on observations, descriptions, and transects of the mapunit.

Description of Udorthents, Sandy

SettingParent material: Loamy alluvium and/or sandy glaciofluvial deposits and/or loamy

glaciolacustrine deposits and/or loamy marine deposits and/or loamy basal till and/or loamy lodgment till

Properties and qualitiesSlope: 0 to 25 percentDepth to restrictive feature: More than 80 inchesDepth to water table: More than 80 inchesFrequency of flooding: NoneFrequency of ponding: None

Minor Components

Urban landPercent of map unit: 5 percentLandform position (two-dimensional): FootslopeLandform position (three-dimensional): Base slope


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Down-slope shape: LinearAcross-slope shape: Linear

Udorthents, loamyPercent of map unit: 5 percentHydric soil rating: No

UnnamedPercent of map unit: 5 percent

655—Udorthents, wet substratum

Map Unit SettingNational map unit symbol: vr1nElevation: 0 to 3,000 feetMean annual precipitation: 32 to 54 inchesMean annual air temperature: 43 to 54 degrees FFrost-free period: 110 to 240 daysFarmland classification: Not prime farmland

Map Unit CompositionUdorthents, wet substratum, and similar soils: 85 percentMinor components: 15 percentEstimates are based on observations, descriptions, and transects of the mapunit.

Description of Udorthents, Wet Substratum




Minor Components

Urban landPercent of map unit: 8 percentLandform position (two-dimensional): FootslopeLandform position (three-dimensional): Base slopeDown-slope shape: LinearAcross-slope shape: Linear

FreetownPercent of map unit: 4 percentLandform: Bogs, depressionsLandform position (two-dimensional): Toeslope


19

Landform position (three-dimensional): DipDown-slope shape: ConcaveAcross-slope shape: ConcaveHydric soil rating: Yes

SwanseaPercent of map unit: 3 percentLandform: Bogs, depressionsLandform position (two-dimensional): ToeslopeLandform position (three-dimensional): DipDown-slope shape: ConcaveAcross-slope shape: ConcaveHydric soil rating: Yes

656—Udorthents-Urban land complex

Map Unit SettingNational map unit symbol: 995kElevation: 0 to 3,000 feetMean annual precipitation: 32 to 54 inchesMean annual air temperature: 43 to 54 degrees FFrost-free period: 110 to 240 daysFarmland classification: Not prime farmland

Map Unit CompositionUdorthents and similar soils: 40 percentUrban land: 40 percentMinor components: 20 percentEstimates are based on observations, descriptions, and transects of the mapunit.

Description of Udorthents




Description of Urban Land

SettingLandform position (two-dimensional): FootslopeLandform position (three-dimensional): Base slopeDown-slope shape: LinearAcross-slope shape: Linear


20

Parent material: Excavated and filled land

Minor Components

CantonPercent of map unit: 10 percentLandform: HillsLandform position (two-dimensional): Backslope, toeslopeLandform position (three-dimensional): Side slope, base slopeDown-slope shape: LinearAcross-slope shape: ConvexHydric soil rating: No

PaxtonPercent of map unit: 5 percentLandform: HillslopesLandform position (two-dimensional): Backslope, summitLandform position (three-dimensional): Head slope, side slopeDown-slope shape: ConvexAcross-slope shape: ConvexHydric soil rating: No

MerrimacPercent of map unit: 5 percentLandform: Terraces, plainsLandform position (two-dimensional): ShoulderLandform position (three-dimensional): Tread, riseDown-slope shape: ConvexAcross-slope shape: ConvexHydric soil rating: No


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ReferencesAmerican Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition.

American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00.

Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31.

Federal Register. July 13, 1994. Changes in hydric soils of the United States.

Federal Register. September 18, 2002. Hydric soils of the United States.

Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States.

National Research Council. 1995. Wetlands: Characteristics and boundaries.

Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_054262

Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577

Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580

Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section.

United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1.

United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/home/?cid=nrcs142p2_053374

United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/landuse/rangepasture/?cid=stelprdb1043084

22

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_054262






http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/home/?cid=nrcs142p2_053374

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/home/?cid=nrcs142p2_053374

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/landuse/rangepasture/?cid=stelprdb1043084

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/landuse/rangepasture/?cid=stelprdb1043084

United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/scientists/?cid=nrcs142p2_054242

United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053624

United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf


23

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/scientists/?cid=nrcs142p2_054242

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/scientists/?cid=nrcs142p2_054242



http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf

http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf

www.haleyaldrich.com

MEMORANDUM 12 September 2018 File No. 41872-034 TO: Lincoln Property Company

John M. Cappellano; Senior Vice President, Development & Construction FROM: Haley & Aldrich, Inc. Scott R. Bamford, Marya E. Gorczyca SUBJECT: Preliminary Design Level Geotechnical Site Evaluation 91 Hartwell Avenue Lexington, Massachusetts The letter presents our Preliminary Design level geotechnical evaluation of the 91 Hartwell Avenue, Lexington, Massachusetts site proposed for a new laboratory building and parking garage. Our geotechnical evaluation is based on observations made during our site visit and on the results of subsurface explorations performed for this study. Executive Summary In summary, the subsurface conditions are characterized by shallow depth to loose to medium dense fine-grained silty soils. Dense, granular glacial till soils and possibly bedrock were encountered at between 34 to 35 ft depth. Groundwater was observed at just below ground surface during our subsurface explorations. We anticipate the proposed new laboratory building and parking garage columns and walls may be supported on either of the following foundation systems:

a) Shallow footings after excavation/replacement of the existing fills with structural fill; b) Pressure-injected footings (PIFs) bearing in the dense glacial till soils and/or bedrock; or c) Driven piles end-bearing in the dense glacial till soils and/or bedrock.

A cost comparison should be made to aid selection of the appropriate foundation system. It is anticipated that the lowest level floor of the laboratory building and parking garage may be a soil-supported, slab-on-grade. Alternatively, the lowest level used for automobile parking in the parking garage may also be designed as a bituminous pavement section, subject to performance and aesthetic considerations and Town of Lexington requirements.

HALEY & ALDRICH, INC. 465 Medford St. Suite 2200 Boston, MA 02129 617.886.7400

Lincoln Property Company 12 September 2018 Page 2

Additional premium site development costs include construction dewatering, management of excavated soils, and possibly pile support. Additional details are provided below. Proposed Redevelopment The proposed development is planned to consist of a new 3-story laboratory building and a 4-story parking garage at 91 Hartwell Avenue in Lexington, Massachusetts (Figure 1, Project Locus). The building will contain 109,900 gross square feet (gsf) of laboratory space and 20,000 gsf of penthouse/roof area. The parking garage is planned for 691 cars. We understand the laboratory building is generally planned at existing grade and the parking garage may contain one-half level of below-grade parking. The planned new buildings would be located north of the existing 3-story office building which will remain. The plan limits of the proposed building and parking garage are shown on Figure 2, Site and Subsurface Exploration Location Plan. Structure loads have not been provided. Elevation Datum Elevations in this report are in feet and refer to the North American Vertical Datum (NAVD) of 1988. Existing Conditions SITE CONDITIONS The Site is located at the intersection of Hartwell Place and Hartwell Avenue in Lexington at 91 Hartwell Avenue. The Site is located between other commercial developments on Hartwell Avenue and Hartwell Place to the north, east and south, and Runway 29 of the Lawrence G. Hanscom Field (Airport) to the west. Refer to Figure 2, Site and Subsurface Exploration Location Plan. The Site currently contains a 3-story commercial building with a plan area of 41,071 square feet (sq ft). The remainder of the Site is paved parking, with landscaped islands and drainage swales, and undeveloped wooded areas with conservation easements. The laboratory building and parking garage are planned on the location of the existing paved parking lots. The site is relatively flat with the area beyond the paved parking lots mostly wooded. Surface grades across the Site range from approximately El. 113 to El. 122. A gas easement exists through the east side of the Site. A drainage easement exists through the west side of the Site. SUBSURFACE CONDITIONS Three test borings were recently drilled at the Site by Haley & Aldrich, Inc. (Haley & Aldrich) at the locations shown on Figure 2 to characterize the shallow soils at the site. Two of the test borings, B-HA-1 and B-HA-3, were used to conduct falling-head permeability tests, as requested by the site Civil Engineering, Paul Finger Associates, for design of a stormwater infiltration system. Test boring B-HA-2 was completed as a groundwater observation well.


Locations of the recent test borings are shown on Figure 2. Logs of the test borings are included in Appendix A. Based on the available test boring data, the site subsurface conditions are summarized as follows in order of depth below ground surface:

General Strata Description Thickness, ft Elevation of Top of Stratum, El., ft

Asphalt/Miscellaneous Fill 3 to 4 Ground Surface Silty Soils 23 to 32 112.2 to 114.7 Dense Glacial Till/Bedrock 0.2-3(1) 80.7 to 81.7

Notes: (1) – Stratum not fully penetrated. Groundwater was measured in observation well B-HA-2 (OW) at 0.83 ft of the ground surface or at approximately El. 115. Standing water was observed around the Site in drainage swales and in the nearby wooded areas at a similar elevation below the parking lot surface. The results of the falling head permeability tests are presented in Appendix B. The tests revealed permeabilities ranging from 2x10E-05 to 6x10E-05 cm/sec. ENVIRONMENTAL SOIL QUALITY Chemical testing of soil and groundwater and an environmental assessment of the Site were not part of our scope for this due diligence effort. Foundation Support The preliminary recommendations provided below are intended for use by the project team in evaluating foundation support and below-grade construction requirements and impacts on building design and construction costs. Although preliminary, our geotechnical considerations were based on the requirements of the current 9th Edition of the Massachusetts State Building Code (Building Code). STRUCTURAL SUPPORT As indicated above, the subsurface conditions are characterized by a 3 to 4 ft thick layer of miscellaneous fill overlying loose to medium dense fine-grained silty soils. Dense, granular glacial till soils and, possibly, bedrock were encountered at between 34 to 35 ft depth. Groundwater was observed 0.83 ft below ground surface.

The miscellaneous fills are considered unsuitable for foundation support. The naturally deposited silty soils encountered at depths of 3 to 4 ft are the top of the suitable foundation bearing soils. Under these conditions, conventional reinforced concrete spread footings with a soil-supported slab-on-grade would generally be the most economical foundation system for low to medium-rise buildings. However, the


silty soils can be characterized as developing low allowable bearing pressures at tolerable settlements for these type of structures. In addition, column spacings for laboratory buildings and parking garages are typically wider than conventional office buildings, therefore columns loads will be higher resulting in larger footings. Study of the soil’s liquefaction-susceptibility, and the magnitude of any seismically-induced settlements during the design earthquake would also be required to evaluate the performance and cost of footing foundations. Consequently, further investigation of these issues would be required if the building and parking garage are supported on footings bearing in the silty soils. Alternatively, the laboratory building and parking garage could be supported on piles or pressure-injected-footings (PIFs), driven into the dense glacial till soils or bedrock. This would limit the impact of seismically-induced settlements on the structural design, and would alleviate the impact of shallow groundwater on preparation of footing bearing surfaces. Consequently, it is recommended the project consider the following foundations to support the laboratory building and parking garage new columns and walls:

a) shallow footing foundations bearing in the shallow loose to dense silty soils after excavation and replacement of the existing miscellaneous fills with structural fill;

b) pressure-injected footings (PIFs) basing out in the dense glacial till soils and/or bedrock; or

c) piles driven to end-bearing in the dense glacial till soils and/or bedrock. Driven piles may consist of precast, prestressed concrete, concrete-filled steel pipe, or steel H-piles.

For preliminary planning purposes, footings should be designed assuming a maximum allowable bearing pressure equal to 4.0 kips per square foot (ksf) bearing in the shallow, loose to medium dense silty soils. Presently, we have limited information on the glacial till and on the type and characterization of the bedrock below the Site. Consequently, we recommend PIFs and driven piles be designed using an allowable axial capacity of 100 tons bearing in the dense glacial till soils and/or bedrock. A comparison of the cost-effectiveness of footings versus PIFs and piles is recommended. Final selection of the foundation system should be made after more information is known about the subsurface conditions, structures, loads and settlement tolerances, in consideration of cost, and potential impacts of foundation installation and other considerations. LOWEST LEVEL FLOORS The lowest level floors, assumed bearing at approximately the existing Site grades or slightly lower if a below-grade parking level is considered for the parking garage, may be soil-supported slabs-on-grade following excavation and replacement of the existing miscellaneous fills. Alternatively, the lowest level floor used for automobile parking in the parking garage may also be designed as a bituminous pavement section, subject to aesthetic considerations and Town of Lexington requirements.


SEISMIC DESIGN Seismic analyses for the Site have not been undertaken. However, based on the available subsurface information, a seismic Site Classification of D (per the 9th edition of the Massachusetts State Building Code) should be considered for preliminary planning, pending further seismic analyses. The soils at the Site are considered not susceptible to liquefaction during the design earthquake in accordance with criteria in the Building Code. PERMANENT GROUNDWATER CONTROL A design groundwater level at ground surface should be used for preliminary design. Considering Site groundwater levels are at or above planned lowest level of the laboratory building (assumed at existing ground surface) and parking garage, a perimeter drain and underslab drain are recommended. Site Work Items and Construction Considerations EXCAVATION AND CONSTRUCTION DEWATERING Excavation of soils can be accomplished by open excavations using normal earth-moving equipment, materials and procedures for excavation and hauling soil. Considering groundwater was observed within 1 ft of the ground surface, the planned construction will be made at and below groundwater. Consequently, construction dewatering will be required to control surface water, stormwater collection, and groundwater entering the excavations in order to facilitate construction in-the-dry. Dewatering of excavations during construction will be required to lower groundwater levels to below excavation levels and to protect the integrity of the fine-grained soils. FILLING AND BACKFILLING Structural fill consisting of well-graded, sand and gravel from an off-site source should be used as backfill below and around footings and below lowest slabs after excavating all unsuitable miscellaneous fills. The on-site miscellaneous fills and silty soils are not suitable for structural fill. Structural fill beneath footings and slabs-on-grade should be placed and compacted in thin lifts and compacted to minimum specified densities. Backfill outside of the structure may consist of Common Fill except for any special filling required for pavements, landscaping, or other site improvements. PILE INSTALLATION Piles should be driven to end-bearing in the dense glacial till and/or bedrock below the Site. PIFs should base out in the same materials below the fills and silty soils at shallower depth.


ENVIRONMENTAL SOIL MANAGEMENT Surplus excavated soils generated during construction will need to be managed in accordance with MA DEP requirements. Environmental characterization of soils will be required by receiving facilities prior to acceptance for off-site transport. This will need to be included in project planning as a future subsurface exploration/soil pre-characterization program. Additional Geotechnical and Environmental Information Needs The thickness of fill and depth to bedrock at additional locations with the building and garage footprints should be confirmed during future design phases of the project. Consequently, depending upon the final foundation system selected, additional investigation of fill thickness and bedrock depth is recommended prior to undertaking final foundation design. If any soil will be generated from the planned construction, chemical characterization will be required to define environmental quality for receiving facilities We trust this information is adequate for your current needs. Please contact us is you have questions or require additional information. Attachments

Figure 1 – Project Locus Figure 2 – Site and Subsurface Exploration Location Plan Appendix A –Test Boring Logs Appendix B – Falling Head Permeability Test Results

G:\41872 - Hartwell St., Lexington\000 - Design\91 Hartwell Ave\Report\Preliminary Design\Text\2018-0912-HAI-Prelim. Geotechncal Evaluation Memo-D3.docx

FIGURES

APPROXIMATE SCALE: 1 IN = 2000 FTAUGUST 2018 FIGURE 1

PROJECT LOCUS

PROPOSED DEVELOPMENT91 HARTWELL AVENUELEXINGTON, MASSACHUSETTS

4187

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SITE COORDINATES: 42°28'2"N, 71°15'49"WMAP SOURCE: ESRI

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APPENDIX A

Test Boring Logs

10121014

5588

4457

0.52.5

4.06.0

14.016.0

SM

ML

ML/CL

S112

S212

S218

115.40.3

112.73.0

-ASPHALT-Medium dense gray silty SAND (SM), mps <1 mm, no structure, no odor,wet, trace asphalt in spoon tip

-FILL-

Medium dense mottled orange brown to gray SILT (ML), mps < 1 mm,laminated, no odor, wet

Note: Performed falling head permability test, HAB01-FHPT1 from4 ft- 6 ft , see levellogger, SN 2069759 data file

Loose tan brown SILT (ML) interbedded with frequent laminae of mediumstiff gray lean CLAY (CL), occasional decomposed gravel clasts

20

100

100

80

3.1*

File No.

36.7

9

Location

HA-B01

Time (hr.)

8/23/18

Inside Diameter (in.)

H&A Rep.

Plasticity: N - Nonplastic L - Low M - Medium H - HighDry Strength: N - None L - Low M - Medium H - High V - Very High

4S0

115.7NAVD 1988

24 -

of CasingBottom

Automatic Hammer

Time

Water Level Data Sample ID

Boring No.

Type

Barrel

Water

Concrete

Hammer Fall (in.)

Bentonite Seal

Finish

Rig Make & Model:

Grout

Dilatancy: R - Rapid S - Slow N - NoneToughness: L - Low M - Medium H - High

Cuttings

NA

None

HA-B01

Samples

Elevation

P. SCHOFIELDDrilling Equipment and Procedures

23 August 20181

D. Warren

Casing

Casing:

PID Make & Model:Hoist/Hammer:

--

~36

Depth (ft) to:

* At completion, not stabilized

Sampler

Overburden (ft)

Rock Cored (ft)

Summary

Field Tests:

2

Screen

Well Diagram

Drill Mud:Hammer Weight (lb) -140

30

1 3/8

--

Elapsed Riser Pipe

Start

Bit Type:S

†Note: Maximum particle size is determined by direct observation within the limitations of sampler size.

41872-034

HW Drive to 9 ft

B48 Mobile Drill Truck

Note: Soil identification based on visual-manual methods of the USCS as practiced by Haley & Aldrich, Inc.

16:30

Sheet No.

23 August 2018

of Hole

See Plan300

Date BottomFilter Sand

Boring No.

Driller

Datum

of

HWRoller Bit

O - Open End Rod

T - Thin Wall Tube

U - Undisturbed Sample

S - Split Spoon Sample

4

ClientContractor NEW ENGLAND BORING CONTRACTORS

ProjectLINCOLN PROPERTY COMPANY91 HARTWELL AVENUE, LEXINGTON, MA

Sam

pler

Blo

ws

per

6 in

.

H&

A-T

ES

T B

OR

ING

-09-

RE

V-2

HA

-LIB

09-B

OS

-HA

R.G

LB

H

A-T

B+

CO

RE

+W

ELL

-09

W F

EN

CE

.GD

T

\

\HA

LEY

ALD

RIC

H.C

OM

\SH

AR

E\B

OS

_CO

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ON

\418

72 -

HA

RT

WE

LL S

T.,

LE

XIN

GT

ON

\GIN

T\4

1872

-034

-TB

-OW

.GP

J

12

Sep

18 Sam

ple

Dep

th (

ft)

TEST BORING REPORT

US

CS

Sym

bol

Dep

th (

ft)

0

5

10

15

20

Sam

ple

No.

& R

ec. (

in.)

Str

atu

mC

hang

eE

lev/

Dep

th (

ft) VISUAL-MANUAL IDENTIFICATION AND DESCRIPTION

(Density/consistency, color, GROUP NAME, max. particle size†,structure, odor, moisture, optional descriptions

GEOLOGIC INTERPRETATION)

% F

ine

% C

oars

e

% M

ediu

m

% F

ine

Dila

tanc

y

% C

oars

e

Tou

ghne

ss

Pla

stic

ity

Str

eng

th

Field Test

% F

ines

Gravel Sand Field Test

7101212

8688

24.026.0

29.031.0

SP/SP-SM

SM

S315

S416

92.723.0

80.735.0

79.236.579.036.7

-GLACIOLACUSTRINE DEPOSITS-

Medium dense tan poorly graded SAND (SP), interbedded wtih seams ofbrown poorly graded poorly graded SAND with silt (SP-SM), mps < 1 mm,stratified, no odor, wet


Medium dense tan silty SAND (SM), mps < 1 mm, no structure, no odor,wet


Note: Drill action indicates coarse granular material approximately 35 ft to36.5 ft

-GLACIOFLUVIAL/GLACIAL TILL DEPOSITSPOSSIBLE TOP OF BEDROCK AT 36.5 ft

Note: Roller bit refusal 36.7 ft, drill indicates very hard sound bedrock-POSSIBLE BEDROCK-

BOTTOM OF EXPLORATION 36.7 ft

10

15

90

85

Sheet No.

HA-B01

2 2of

NOTE: Soil identification based on visual-manual methods of the USCS as practiced by Haley & Aldrich, Inc.

Boring No.

File No.

Boring No. HA-B01

41872-034

Sam

pler

Blo

ws

per

6 in

.

H&

A-T

ES

T B

OR

ING

-09-

RE

V-2

HA

-LIB

09-B

OS

-HA

R.G

LB

H

A-T

B+

CO

RE

+W

ELL

-09

W F

EN

CE

.GD

T

\

\HA

LEY

ALD

RIC

H.C

OM

\SH

AR

E\B

OS

_CO

MM

ON

\418

72 -

HA

RT

WE

LL S

T.,

LE

XIN

GT

ON

\GIN

T\4

1872

-034

-TB

-OW

.GP

J

12

Sep

18

Sam

ple

Dep

th (

ft)

TEST BORING REPORT

US

CS

Sym

bol

Dep

th (

ft)

20

25

30

35

Sam

ple

No.

& R

ec. (

in.)

Str

atu

mC

hang

eE

lev/

Dep

th (




% F

ine

% C

oars

e

% M

ediu

m

% F

ine

Dila

tanc

y

% C

oars

e

Tou

ghne

ss

Pla

stic

ity

Str

eng

th

Field Test

% F

ines


561014

4555

3468

45109

23

0.52.5

4.06.0

9.011.0

14.016.0

19.021.0

SW-SM

ML./MH

ML

ML

ML

S19

S212

S315

S418

S520

115.30.4

112.23.5

-ASPHALT-Medium dense gray well graded SAND with silt and gravel (SW-SM),mps = 1.5 in., no structure, no odor, wet

-FILL-Note: Trace organic soils noted in wash at bottom of fill

S2: Stiff gray SILT/ELASTIC SILT (ML/MH), mps <1 mm,laminated, no odor, wet

Medium dense gray SILT (ML) with occasional orange brown oxidizedseams, mps <1 mm, no structure, no odor, wet

Medium dense tan SILT (ML), mps <1 mm, laminated, no odor, wet

Losse tan SILT with trace fine sand (ML), mps <1 mm, no structure,no odor, wet

15 20 20 10

100

100

100

100

15 20

4.8*

File No.

34.2

0.3**

Location

HA-B02 (OW)

Time (hr.)

8/22/18


H&A Rep.


40 min. 7S0

115.7NAVD 1988

24 -

of CasingBottom

Automatic Hammer

Time


Boring No.

Type

Barrel

Water

Concrete

Hammer Fall (in.)

Bentonite Seal

Finish

08/23/18

Rig Make & Model:

Grout


Cuttings

NA

None

HA-B02(OW)

Samples

0.83

Elevation

P. SchofieldDrilling Equipment and Procedures

22 August 2018

9:34

1

D. Warren

Casing

Casing:


--

34.2

Depth (ft) to:

13.516:00

Sampler

Overburden (ft)

Rock Cored (ft)

28.2

Summary

Field Tests:

2

Screen

Well Diagram


30

1 3/8

--

Elapsed Riser Pipe

Start

Bit Type:S


41872-034

HW Drive to 29 ft



08/28/18

12:30

Sheet No.

22 August 2018

of Hole

See Plan300


Boring No.

Driller

141.7

Datum

of

HWRoller Bit

O - Open End Rod

T - Thin Wall Tube



4



Sam

pler

Blo

ws

per

6 in

.

H&

A-T

ES

T B

OR

ING

-09-

RE

V-2

HA

-LIB

09-B

OS

-HA

R.G

LB

H

A-T

B+

CO

RE

+W

ELL

-09

W F

EN

CE

.GD

T

\

\HA

LEY

ALD

RIC

H.C

OM

\SH

AR

E\B

OS

_CO

MM

ON

\418

72 -

HA

RT

WE

LL S

T.,

LE

XIN

GT

ON

\GIN

T\4

1872

-034

-TB

-OW

.GP

J

12

Sep

18 Sam

ple

Dep

th (

ft)

TEST BORING REPORT

US

CS

Sym

bol

Dep

th (

ft)

0

5

10

15

20

Sam

ple

No.

& R

ec. (

in.)

Wel

l Dia

gram

Str

atu

mC

hang

eE

lev/

Dep

th (




% F

ine

% C

oars

e

% M

ediu

m

% F

ine

Dila

tanc

y

% C

oars

e

Tou

ghne

ss

Pla

stic

ity

Str

eng

th

Field Test

% F

ines


55

7101116

45710

24.026.0

29.031.0

SW

CL-ML

S616

S720

92.223.5

87.728.0

81.734.081.534.2


Medium dense brown well graded SAND with trace gravel (SW), mps1.5 in., no structure, no odor, moist

-GLACIOFLUVIAL DEPOSITS-

Stiff gray lean CLAY (CL) interbedded with laminae and seams ofgray SILT (ML), mps <1 mm, laminated, no odor, wet


POSSIBLE TOP OF BEDROCK AT 34.0 ft

Note: Roller bit refusal 34.2 ft, drill action indicates very hard soundbedrock

-POSSIBLE BEDROCK-BOTTOM OF EXPLORATION 34.2 ft.

Notes:- Ground water observaton well installed at 13.5 ft upon completion- * Water level trapped, not stabilized at 4.8 ft- ** Inital OW reading, not stabilized 0.03 ft

5 5 25

100

40 25

Sheet No.

HA-B02 (OW)

2 2of


Boring No.

File No.

Boring No. HA-B02 (OW)

41872-034

Sam

pler

Blo

ws

per

6 in

.

H&

A-T

ES

T B

OR

ING

-09-

RE

V-2

HA

-LIB

09-B

OS

-HA

R.G

LB

H

A-T

B+

CO

RE

+W

ELL

-09

W F

EN

CE

.GD

T

\

\HA

LEY

ALD

RIC

H.C

OM

\SH

AR

E\B

OS

_CO

MM

ON

\418

72 -

HA

RT

WE

LL S

T.,

LE

XIN

GT

ON

\GIN

T\4

1872

-034

-TB

-OW

.GP

J

12

Sep

18

Sam

ple

Dep

th (

ft)

TEST BORING REPORT

US

CS

Sym

bol

Dep

th (

ft)

20

25

30

Sam

ple

No.

& R

ec. (

in.)

Wel

l Dia

gram

Str

atu

mC

hang

eE

lev/

Dep

th (




% F

ine

% C

oars

e

% M

ediu

m

% F

ine

Dila

tanc

y

% C

oars

e

Tou

ghne

ss

Pla

stic

ity

Str

eng

th

Field Test

% F

ines


0.4

3.5

23.5

28.0

34.0

114.7114.2

112.7112.2

102.2101.7

96.7

92.2

81.5

ASPHALT

FILL

FILL

GLACIOFLUVIALDEPOSITS

GLACIOLACUSTRINEDEPOSITS

1.01.5

3.03.5

13.514.0

19.0

23.5

34.2

0.0

Inside diameter of riser pipe

Depth of bottom of riser pipe

Type of riser pipe Schedule 40 PVC

Roadway Box

Length

Type of Backfill around Screen Filter Sand

Type of screen Machine slotted Sch 40 PVC

Depth of bottom of Roadway Box

Type of protective casing

Type of protective cover

Concrete

Bentonite

Bentonite

0

5

10

15

20

25

30

34.2Top of Possible Bedrock atr 34.0 ft.

34.2 ft

--

1.5

GROUNDWATER OBSERVATION WELLINSTALLATION REPORT

Inside diameter

Location

41872-034

DE

PT

H(f

t.)

115.7

WELL

DETAILS

COMMENTS:

D. Warren

CONDITIONS

HA-B02 (OW)

GR

AP

HIC

Screen

Depth to top of well screen 3.5 ft

Well Diagram

Concrete

ELE

VA

TIO

N(f

t.)

Compression Cover

H&A Rep.

Datum

Riser Pipe

Boring No.

Bentonite Seal

Bottom of silt trap

NAVD 1988

CuttingsGrout

Well No.

File No.

DE

PT

H(f

t.)

Ground El.

8.0 in.

Project

Client

P. Schofield

91 HARTWELL AVENUE

Depth to bottom of well screen

LEXINGTON, MA

Contractor

Driller

Location

Filter Sand

Initial Water Level (depth bgs)

WELL CONSTRUCTION DETAILS

SOIL/ROCK

Date Installed

Depth of bottom of borehole

See PlanLINCOLN PROPERTY COMPANY

115.7

Diameter of borehole

1.0 ft

2.0 in.

14.0

1.0

1.5

5.0

NEW ENGLAND BORING CONTRACTORS

HA-B02(OW)

0.0 ft

0.2 ft

Diameter of screen 2.0 in.

Screen gauge or size of openings 0.010 in.

Depth of top of riser below ground surface

Depth of Roadway Box below ground surface

3.5 ft

4.5 in.

13.5 ft

0.0

3.5 ft

22 Aug 2018

1.0 ft

Type of Seals Top of Seal (ft) Thickness (ft)

HA

-LIB

09-B

OS

-HA

R.G

LB

G

W I

NS

TA

LLA

TIO

N R

EP

OR

T-0

7-1

\

\HA

LEY

ALD

RIC

H.C

OM

\SH

AR

E\B

OS

_CO

MM

ON

\418

72 -

HA

RT

WE

LL S

T.,

LE

XIN

GT

ON

\GIN

T\4

1872

-034

-TB

-OW

.GP

J

12

Sep

18

12111010

18111514

4567

10141417

913

0.52.5

4.06.0

9.011.0

14.016.0

19.021.0

SP-SM

SP-SM

SP-SM

S110

S215

S314

S418

S512

118.30.4

114.74.0

-ASPHALT-Medium dense brown poorly graded SAND with silt and gravel (SP-SM),mps = 1 in., no structure, no odor, moist, with cobbles

-FILL-

Note: When drilling casing to 4 ft, casing bent on boulder in fill atapproximately 3 ft. Relocated hole approximately East.

Medium dense brown silty SAND (SM), mps <1mm, no structure, no odor,wet

Note: Performed falling head permability test HA-B03-FHPT-1 from 4-6 ft,see level logger SN 2069759 data file

Similar to about with occassional mottled orange brown seams

Medium dense red brown to tan poorly graded SAND with silt (SP-SM), mps<1mm, stratified, no odor, wet

Similar to above except gray brown

5 5 10 10

15

35

10

10

20 50

85

65

90

90

4.2

File No.

30

Location

HA-B03

Time (hr.)

8/23/18


H&A Rep.


7S0

118.7NAVD 1988

24 -

of CasingBottom

Automatic Hammer

Time


Boring No.

Type

Barrel

Water

Concrete

Hammer Fall (in.)

Bentonite Seal

Finish

Rig Make & Model:

Grout


Cuttings

NA

None

HA-B03

Samples

Elevation

P. SchofieldDrilling Equipment and Procedures

22 August 20181

D. Warren

Casing

Casing:


--

30.0

Depth (ft) to:

Sampler

Overburden (ft)

Rock Cored (ft)

Summary

Field Tests:

2

Screen

Well Diagram


30

1 3/8

--

Elapsed Riser Pipe

Start

Bit Type:S


41872-034

HW Drive to 28 ft



12:00

Sheet No.

23 August 2018

of Hole

See Plan300


Boring No.

Driller

Datum

of

HWRoller Bit

O - Open End Rod

T - Thin Wall Tube



4



Sam

pler

Blo

ws

per

6 in

.

H&

A-T

ES

T B

OR

ING

-09-

RE

V-2

HA

-LIB

09-B

OS

-HA

R.G

LB

H

A-T

B+

CO

RE

+W

ELL

-09

W F

EN

CE

.GD

T

\

\HA

LEY

ALD

RIC

H.C

OM

\SH

AR

E\B

OS

_CO

MM

ON

\418

72 -

HA

RT

WE

LL S

T.,

LE

XIN

GT

ON

\GIN

T\4

1872

-034

-TB

-OW

.GP

J

12

Sep

18 Sam

ple

Dep

th (

ft)

TEST BORING REPORT

US

CS

Sym

bol

Dep

th (

ft)

0

5

10

15

20

Sam

ple

No.

& R

ec. (

in.)

Str

atu

mC

hang

eE

lev/

Dep

th (




% F

ine

% C

oars

e

% M

ediu

m

% F

ine

Dila

tanc

y

% C

oars

e

Tou

ghne

ss

Pla

stic

ity

Str

eng

th

Field Test

% F

ines


139

3434

44161617

24.026.0

28.030.0

ML

ML-CL

S618

S720

96.722.0

91.727.0

88.730.0


Loose gray SILT (ML), mps <1mm, no structure, no odor, wet

-GLACIOLACUSTRINE DEPOSITS-Note: Drill action indicates strata change 27 ft

Dense gray SILT, trace lean CLAY in frequent laminae, mps <1mm,laminated, no odor, wet


BOTTOM OF EXPLORATION 30 ft

65

100

35

Sheet No.

HA-B03

2 2of


Boring No.

File No.

Boring No. HA-B03

41872-034

Sam

pler

Blo

ws

per

6 in

.

H&

A-T

ES

T B

OR

ING

-09-

RE

V-2

HA

-LIB

09-B

OS

-HA

R.G

LB

H

A-T

B+

CO

RE

+W

ELL

-09

W F

EN

CE

.GD

T

\

\HA

LEY

ALD

RIC

H.C

OM

\SH

AR

E\B

OS

_CO

MM

ON

\418

72 -

HA

RT

WE

LL S

T.,

LE

XIN

GT

ON

\GIN

T\4

1872

-034

-TB

-OW

.GP

J

12

Sep

18

Sam

ple

Dep

th (

ft)

TEST BORING REPORT

US

CS

Sym

bol

Dep

th (

ft)

20

25

30

Sam

ple

No.

& R

ec. (

in.)

Str

atu

mC

hang

eE

lev/

Dep

th (




% F

ine

% C

oars

e

% M

ediu

m

% F

ine

Dila

tanc

y

% C

oars

e

Tou

ghne

ss

Pla

stic

ity

Str

eng

th

Field Test

% F

ines


APPENDIX B

Falling Head Permeability Test Results

TAB

LE I

RES

ULT

S O

F IN

-SIT

U B

OR

EHO

LE P

ERM

EAB

ILIT

Y TE

STS

91 H

ARTW

ELL

AVE

LEXI

NG

TON

MA

File

No.

41

872-

034

Test

Test

Gro

und

Test

Zon

eSo

il St

ratu

mB

orin

gD

ate

Surf

ace

El.

Dep

th, f

tof

Tes

t Zon

eSc

hmid

2H

vors

lev

Geo

mea

n

HA-

BO1

23-A

ug-1

8--

4 to

6Si

lt3E

-05

2E-0

53.

E-05

HA-

BO3

23-A

ug-1

8--

4 to

6Si

lty S

and

5E-0

56E

-05

5.E-

05

1. T

ests

wer

e in

-situ

bor

e ho

le p

erm

eabi

lity

test

s pe

rform

ed b

y th

e fa

lling

head

met

hod.

2.

Ref

eren

ce: W

. E. S

chm

id, "

Fiel

d D

eter

min

atio

n of

Per

mea

bilit

y by

the

Infil

tratio

n Te

sts,

" Per

mea

bilit

y an

d C

apilla

rity

of S

oils

,

AS

TM S

TP 4

17, A

mer

ican

Soc

iety

of T

estin

g M

ater

ials

, 196

7, p

. 142

.

Estim

ated

Per

mea

bilit

y, k

, cm

/sec

.


APPENDIX F

DRAFT Stormwater Pollution Prevention Plan (SWPPP)

i

DRAFT Stormwater Pollution Prevention Plan (SWPPP)

For Construction Activities At:

91 Hartwell Avenue Lexington, MA 02421

Site Telephone Number: xxx-xxx-xxxx

SWPPP Prepared For:

Paul Finger Associates Contact Person

14 Spring Street

Waltham, MA 02451-4429

T: xxx-xxx-xxxx

Email Address/Fax Number

SWPPP Prepared By:

Nitsch Engineering Matthew Brassard

Joshua Soares

2 Center Plaza

Boston, MA 02108

T: 617-338-0063

F: 617-338-6472

SWPPP Preparation Date:

10/25/2019

Estimated Project Dates:

Project Start Date: XX/XX/XXXX Project Completion Date: XX/XX/XXXX

DRAFT Stormwater Pollution Prevention Plan 91 Hartwell Avenue

ii

Nitsch SWPPP Directions:

Yellow Highlighted Text should be filled in with relevant information to your project or removed if it is not applicable. Blue highlighted text is intended as direction on how to fill out the SWPPP and should be deleted before being sent out.

• Read through 2017 CGP prior to preparation of this document.

• Remove information that is not relevant to your project and add information as needed (for

example, you may not need all the BMPs listed in Section 4).

• If the project receives and Order of Conditions (OOC), review the OOC to determine if it has

stricter regulations than the SWPPP. Update the SWPPP as necessary to match the OOC.

Note: There are many exceptions in the CGP regarding Linear Projects. If you are completing a SWPPP for a liner project, you should carefully read through the CGP and edit your document as appropriate. Delete this page and all text on it before sending out the SWPPP.


iii

Contents

SECTION 1: CONTACT INFORMATION/RESPONSIBLE PARTIES .......................................... 5

1.1 Operator(s) / Subcontractor(s) ............................................................................................ 5

1.2 Stormwater Team ............................................................................................................... 7

SECTION 2: SITE EVALUATION, ASSESSMENT, AND PLANNING ........................................ 8

2.1 Project/Site Information ...................................................................................................... 8

2.2 Discharge Information ......................................................................................................... 9

2.3 Nature of the Construction Activity ................................................................................... 11

2.4 Sequence and Estimated Dates of Construction Activities ............................................... 12

2.5 Allowable Non-Stormwater Discharges ............................................................................ 13

2.6 Site Maps .......................................................................................................................... 14

SECTION 3: DOCUMENTATION OF COMPLIANCE WITH OTHER FEDERAL REQUIREMENTS ....................................................................................................................... 15

3.1 Endangered Species Protection ....................................................................................... 15

3.2 Historic Preservation ......................................................................................................... 17

3.3 Safe Drinking Water Act Underground Injection Control Requirements ........................... 18

SECTION 4: EROSION AND SEDIMENT CONTROLS REQUIREMENTS ............................... 20

4.1 Natural Buffers or Equivalent Sediment Controls ............................................................. 20

4.3 Sediment Track-Out .......................................................................................................... 24

4.4 Stockpiled Sediment or Soil .............................................................................................. 25

4.6 Minimize the Disturbance of Steep Slopes ....................................................................... 27

4.7 Preserve Native Topsoil .................................................................................................... 29

4.8 Minimize Soil Compaction ................................................................................................ 29

4.9 Storm Drain Inlets ............................................................................................................. 29

4.10 Minimize Erosion of Stormwater Conveyances ................................................................ 30


iv

4.12 Chemical Treatment ......................................................................................................... 32

4.13 Dewatering Practices ........................................................................................................ 33

4.14 Other Stormwater Controls ............................................................................................... 34

4.15 Site Stabilization ............................................................................................................... 34

SECTION 5: POLLUTION PREVENTION STANDARDS .......................................................... 36

5.1 Potential Sources of Pollution ........................................................................................... 36

5.2 Spill Prevention and Response ......................................................................................... 38

5.3 Fueling and Maintenance of Equipment or Vehicles ........................................................ 38

5.4 Washing of Equipment and Vehicles ................................................................................ 39

5.5 Storage, Handling, and Disposal of Construction Products, Materials, and Wastes ........ 39

5.6 Washing of Applicators and Containers used for Paint, Concrete, or Other Materials ..... 42

5.8 Other Pollution Prevention Practices ................................................................................ 43

SECTION 6: INSPECTION AND CORRECTIVE ACTION ......................................................... 44

6.1 Inspection Personnel and Procedures .............................................................................. 44

6.2 Corrective Action .............................................................................................................. 45

6.3 Delegation of Authority ..................................................................................................... 45

SECTION 7: TRAINING LOG ..................................................................................................... 46

SECTION 8: CERTIFICATION AND NOTIFICATION ................................................................ 47

SWPPP ATTACHMENTS ........................................................................................................... 48


5

SECTION 1: CONTACT INFORMATION/RESPONSIBLE PARTIES

1.1 Operator(s) / Subcontractor(s)

Operator(s):

Construction Manager Responsibilities:

Construction Manager shall maintain the Stormwater Pollution Prevention Plan (SWPPP) documentation and will conduct and document self-inspections required under the 2017 Construction General Permit (CGP) once every 7 days and within 24 hours of a storm event 0.25” or greater. OR once every 14 days and within 24 hours of a storm event 0.25” or greater. Construction Manager will provide copies of inspections reports to the Owner’s Representative within 24 hours following each inspection. Incidents of non-compliance will be immediately brought to the attention of the Owner’s Representative. Construction Manager shall be responsible for maintaining compliance with the SWPPP, including all requirements in the CGP and will maintain erosion and sediment control Best Management Practices (BMPs) in all areas of the site under its day-to-day control.

Construction Manager shall file a Notice of Intent (NOI) to be covered by the CGP and obtain coverage by the Environmental Protection Agency (EPA) before beginning construction at the project. Permit coverage will be maintained throughout the project. Construction Manager shall not file a Notice of Termination (NOT) until all disturbed areas of the site under its day-to-day control have been fully stabilized with permanent erosion controls that satisfy the final stabilization requirements in the CGP or have met another criteria of the NOT. Construction Manager will maintain a clean site and construction trash and debris will be picked up and disposed of properly by the end of each day.

Each Operator is responsible for advising employees and subcontractors working on this project of the requirements in the CGP and SWPPP. Particular emphasis should be placed on ensuring that employees and subcontractors do not damage BMPs and maintain compliance with the CGP.

Construction Manager Company Name

Construction Manager Contact Person, Position

Street Address

Town, State, Zip Code

T: xxx-xxx-xxxx

Email address:


6

Owner’s Representative Responsibilities:

Owner’s Representative shall provide general oversight of the project including review of the SWPPP and any amendments, inspection reports, and corrective actions. Owner’s Representative shall file a NOI to be covered by the CGP and obtain coverage by the EPA before beginning construction at the project. Permit coverage will be maintained throughout the project. Owner’s Representative shall not file a notice of Termination until all disturbed areas of the site have been fully stabilized with permanent erosion controls that satisfy the final stabilization requirements in the CGP. Owner’s Representative will coordinate with the Construction Manager to maintain a clean site so that trash and debris will be picked up and disposed of properly by the end of the day.

Each Operator is responsible for advising employees and subcontractors working on this project of the requirements in the CGP and SWPPP. Particular emphasis should be placed on ensuring that employees and subcontractors do not damage BMPs and maintain compliance with the CGP.

Owner’s Representative Company Name

Owner’s Representative Contact person, Position

Street Address


T: xxx-xxx-xxxx

Email Address:

Site Contractor(s):

Company Name

Contact person, Position

Street Address


T: xxx-xxx-xxxx

Email Address: If there is more than one Site Contractor conducting earth disturbing activities then list them all here.

Emergency 24-Hour Contact:

Company

Emergency Contact person, Position

T: xxx-xxx-xxxx


7

1.2 Stormwater Team

Construction Manager: Company Stormwater Role/Responsibility: Responsible for overseeing the development of the SWPPP, modifications and updates to the SWPPP, and for compliance with the requirements in the CGP (e.g., installing and maintaining stormwater controls, conducting site inspections, picking up trash, taking corrective actions where required, etc.). Contact:

Construction Manager Contact Person, Position

T: xxx-xxx-xxxx

Email address I, Construction Manager Contact Person, have read the CGP and Understand the Applicable Requirements

☐ Yes

Date: __________ Site Contractor: Company

Stormwater Role/Responsibility: Responsible for compliance with the requirements in this permit (e.g., installing and maintaining stormwater controls, conducting site inspections, taking corrective actions where required, etc.).

Contact:

Contact Person, Position

T: xxx-xxx-xxxx

Email Address Refer to the Subcontractor Certifications/Agreements in Attachment G. Add more companies to the team as needed


8

SECTION 2: SITE EVALUATION, ASSESSMENT, AND PLANNING

2.1 Project/Site Information

Project Name and Address

Project/Site Name: 91 Hartwell Avenue

Project Street/Location: 91 Hartwell Avenue

City/Town: Lexington

State: Massachusetts

ZIP Code: 02421

County or Similar Subdivision: Middlesex

Project Latitude/Longitude

(Use one of three possible formats, and specify method)

Latitude: Longitude:

1. 42.4669º (degrees, decimals) 1. -71.2638º (degrees, decimals)

Method for determining latitude/longitude:

USGS topographic map (specify scale: ) GPS

Other (please specify):

Horizontal Reference Datum:

NAD 27 NAD 83 WGS 84

If you used a U.S.G.S topographic map, what was the scale? ____________________________

Additional Project Information

Is the project/site located on Indian country lands, or located on a property of religious or cultural significance to an Indian tribe? Yes No Are you applying for permit coverage as a “federal operator” as defined in Appendix A of the CGP?

Yes No Will there be demolition of any structure built or renovated before January 1, 1980?

Yes No

If yes, do any of the structures being demolished have at least 10,000 square feet of floor space? Yes No

Was pre-development land use used for agriculture (see Appendix A of the CGP for definition of “agricultural land”)? Yes No Type of Construction Site (check all that apply): Single-Family Residential Multi-Family Residential Commercial Industrial Institutional Highway or Road Utility Other _____________


9

2.2 Discharge Information

Does your project/site discharge stormwater into a Municipal Separate Storm Sewer System (MS4)? Yes No

Are there any surface waters that are located within 50 feet of your construction disturbances?

Yes No

DR

AF

T S

torm

wate

r P

ollu

tio

n P

reventio

n P

lan

91 H

art

we

ll A

venu

e

1

0

Tab

le 1

– N

am

es o

f R

eceiv

ing

Wate

rs

Nam

e(s

) of

the

first

surf

ace w

ate

r th

at

receiv

es s

torm

wate

r directly f

rom

yo

ur

site a

nd/o

r fr

om

the M

S4 (

note

:

multip

le r

ow

s p

rovid

ed w

here

yo

ur

site h

as m

ore

than o

ne p

oin

t of

dis

ch

arg

e t

hat

flo

ws t

o d

iffe

rent

surf

ace

wate

rs)

001.

Sh

aw

sh

een

Riv

er

002.

003.

Tab

le 2

– Im

pair

ed

Wate

rs / T

MD

Ls (

Answ

er

the f

ollo

win

g f

or

each s

urf

ace w

ate

r lis

ted in T

able

1 a

bove)

Is t

his

surf

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11

2.3 Nature of the Construction Activity

General Description of Project

Provide a general description of the construction project:

Insert a description that includes the nature of your construction activities and the age or dates of past renovations for structures that are undergoing demolition.

Size of Construction Project

What is the size of the property (in acres), the total area expected to be disturbed by the construction activities (in acres), and the maximum area expected to be disturbed at any one time?

Size of Property: xx acres

Total Area of Construction Disturbances: xx acres

Maximum Area to be Disturbed at Any One Time: xx acres

Construction Support Activities Describe any construction support activities for the project including offsite construction support activities (e.g., concrete or asphalt batch plants, equipment staging yards, material storage areas, excavated material disposal areas, borrow areas). Include areas offsite

Include a description of the construction support activities or reference Site Maps in Attachment A that include this information.

Contact Information for Construction Support Activity:

Note: this may be the same as the contractor or site contractor. If it is an offsite activity, it may be different.

Name: XXX

Telephone: XXX-XXX-XXXX

Email: XXXX

Address and/or Latitude and Longitude: (if offsite)

Business Hours

Day-Day Xa.m-Xp.m.


12

2.4 Sequence and Estimated Dates of Construction Activities

Phase I: Name of Phase

• Description of Phase

• Schedule: Month, Day Year – Month, Day Year

• Area Disturbed During Phase: xx acres

• Description of stormwater controls that will be installed/maintained during phase (See example below) Phase I: Demolition This phase consists of the demolition of site features and utilities as shown on the Site Preparation Plan provided in Attachment A.

• Schedule: April 3, 2017-April 30, 2017

• Area Disturbed During Phase: 1.5 acres

• This phase will include the installation of all stormwater control measures as shown on the Site Preparation Plan provided in Attachment A. Stormwater controls will be removed at the end of Phase III upon stabilization of the site.

Phase II: Exterior Utilities This phase consists of the installation of all exterior utilities on the site.

• Schedule: April 3, 2017-July 1, 2017


• All stormwater controls will be installed prior to earth disturbance as described in Phase I. Stormwater controls will be removed at the end of Phase III upon stabilization of the site.

Phase III: Landscaping and Paving This phase consists of the landscaping and paving of the site.

• Schedule: July 1, 2017-September 30, 2017


• Stormwater controls will be installed as described in Phase I. Stormwater controls will remain in place until site work is complete and the site is stabilized.


13

2.5 Allowable Non-Stormwater Discharges

List of Allowable Non-Stormwater Discharges Present at the Site

Type of Allowable Non-Stormwater Discharge Likely to be Present at Your Site?

Discharges from emergency fire-fighting activities YES NO

Fire hydrant flushings YES NO

Landscape irrigation YES NO

Waters used to wash vehicles and equipment, provided that there is no discharge of soaps, solvents, or detergents used for such purposes

YES NO

Water used to control dust YES NO

Potable water including uncontaminated water line flushings YES NO

External building washdown, provided soaps, solvents, and detergents are not used, and external surfaces do not contain hazardous substances (as defined in Appendix A of the CGP) (e.g., paint or caulk containing polychlorinated biphenyls (PCBs))

YES NO

Pavement wash waters, provided spills or leaks of toxic or hazardous substances have not occurred (unless all spill material has been removed) and where soaps, solvents, and detergents are not used.

YES NO

Uncontaminated air conditioning or compressor condensate YES NO

Uncontaminated, non-turbid discharges of ground water or spring water YES NO

Foundation or footing drains where flows are not contaminated with process materials such as solvents or contaminated groundwater

YES NO

Construction dewatering water discharged in accordance with Part 2.4 of the CGP YES NO

Note: You are prohibited from directing pavement wash waters directly into any water of the U.S., storm drain inlet, or stormwater conveyance, unless the conveyance is connected to a sediment basin, sediment trap, or similarly effective control.


14

2.6 Site Maps

Site Maps must include the following: a) Boundaries of the property. The map(s) in the SWPPP must show the overall boundary of the property.

b) Locations where construction activities will occur. The map(s) in the SWPPP must show the locations where

construction activities will occur, including

i. Locations where earth-disturbing activities will occur (note any phasing), including any demolition

activities;

ii. Approximate slopes before and after major grading activities (note any steep slopes);

iii. Locations where sediment, soil, or other construction materials will be stockpiled;

iv. Any water of the U.S. crossings;

v. Designated points where vehicles will exit onto paved roads;

vi. Locations of structures and other impervious surfaces upon completion of construction; and

vii. Locations of onsite and off-site construction support activity areas covered by the permit (see Part

1.2.1.c).

c) Locations of all waters of the U.S. within and one mile downstream of the site’s discharge point. Also

identify if any are listed as impaired, or are identified as a Tier 2, Tier 2.5, or Tier 3 water.

d) Areas of federally listed critical habitats within the site and/or at discharge locations.

e) Type and extent of pre-construction cover on the site (e.g., vegetative cover, forest, pasture, pavement,

structures).

f) Drainage patterns of stormwater and authorized non-stormwater before and after major grading activities.

g) Stormwater and authorized non-stormwater discharge locations. The permit requires the site map to show

information pertaining to discharge locations including:

i. Locations where stormwater and/or authorized non-stormwater will be discharges to storm drain

inlets; and

ii. Locations where stormwater and/or authorized non-stormwater will be discharged directly to waters

of the U.S.

h) Locations of all potential pollutant-generating activities identified in Part 7.2.3.g. The permit requires

identification in the site map of all potential pollutant-generating activities identified in Part 7.2.3.g.

i) Locations of stormwater controls, including natural buffer areas and any shared controls utilized to comply

with this permit. The permit requires identification on the site map of the location of stormwater control

measures.

j) Locations where polymers, flocculants, or other treatment chemicals will be used and stored. The permit

requires identification on the site map of the locations where polymers, flocculants, or other treatment

chemicals will be used and stored.

Refer to Attachment A Include the following if possible:

• LOCUS Map created with GIS

• USGS Map created with GIS

• Phasing Plans/Mobilization Plans/Construction Management Plans from the contractor

• Erosion and Sedimentation Control Plans


15

SECTION 3: DOCUMENTATION OF COMPLIANCE WITH OTHER FEDERAL REQUIREMENTS

3.1 Endangered Species Protection

Check NHESP Data layer (August 2017 or as amended) from MassGIS (this is in the Nitsch permitting GIS template) and U.S. Fish and Wildlife online system Information for Planning and Conservation (IPaC) for endangered species.

Eligibility Criterion

Under which criterion listed in Appendix D of the CGP are you eligible for coverage under this permit?

A B C D E

For reference purposes, the eligibility criteria listed in Appendix D of the CGP are as follows:

Criterion A. No federally-listed threatened or endangered species or their designated critical habitat(s) are likely to occur in your site’s “action area” as defined in Appendix A of the CGP.

Criterion B. The construction site’s discharges and discharge-related activities were already addressed in another operator’s valid certification of eligibility for your action area under eligibility Criterion A, C, D, E, or F and there is no reason to believe that federally-listed species or federally-designated critical habitat not considered in the prior certification may be present or located in the “action area”. To certify your eligibility under this Criterion, there must be no lapse of NPDES permit coverage in the other operator’s certification. By certifying eligibility under this Criterion, you agree to comply with any effluent limitations or conditions upon which the other operator's certification was based. You must include in your NOI the tracking number from the other operator’s notification of authorization under this permit. If your certification is based on another operator’s certification under Criterion C, you must provide EPA with the relevant supporting information required of existing dischargers in Criterion C in your NOI form.

Criterion C. Federally-listed threatened or endangered species or their designated critical habitat(s) are likely to occur in or near your site’s “action area,” and your site’s discharges and discharge-related activities are not likely to adversely affect listed threatened or endangered species or critical habitat. This determination may include consideration of any stormwater controls and/or management practices you will adopt to ensure that your discharges and discharge-related activities are not likely to adversely affect listed species and critical habitat. To make this certification, you must include the following in your NOI: 1) any federally listed species and/or designated habitat located in your “action area”; and 2) the distance between your site and the listed species or designated critical habitat (in miles). You must also include a copy of your site map with your NOI.

Criterion D. Coordination between you and the Services has been concluded. The coordination must have addressed the effects of your site’s discharges and discharge-related activities on federally-listed threatened or endangered species and federally-designated critical habitat, and must have resulted in a written concurrence from the relevant Service(s) that your site’s discharges and discharge-related activities are not likely to adversely affect listed species or critical habitat. You must include copies of the correspondence between yourself and the Services in your SWPPP and your NOI.


16

Criterion E. Consultation between a Federal Agency and the U.S. Fish and Wildlife Service and/or the National Marine Fisheries Service under section 7 of the ESA has been concluded. The consultation must have addressed the effects of the construction site’s discharges and discharge-related activities on federally-listed threatened or endangered species and federally-designated critical habitat. The result of this consultation must be either:

i. a biological opinion that concludes that the action in question (taking into account the effects of your site’s discharges and discharge-related activities) is not likely to jeopardize the continued existence of listed species, nor the destruction or adverse modification of critical habitat; or

ii. written concurrence from the applicable Service(s) with a finding that the site’s discharges and discharge-related activities are not likely to adversely affect federally-listed species or federally-designated habitat.

You must include copies of the correspondence between yourself and the Services in your SWPPP and your NOI.

Criterion F. Your construction activities are authorized through the issuance of a permit under section 10 of the ESA, and this authorization addresses the effects of the site’s discharges and discharge-related activities on federally-listed species and federally-designated critical habitat. You must include copies of the correspondence between yourself and the Services in your SWPPP and your NOI.

For criterion A, indicate the basis for your determination that no federally-listed threatened or endangered species or their designated critical habitat(s) are likely to occur in your site’s action area (as defined in Appendix A of the CGP). Check the applicable source of information you relied upon:

Specific communication with staff of the U.S. Fish & Wildlife Service or National Marine Fisheries Service.

Publicly available species list.

Other source: NHESP data layer (August 2017 or as amended) from MassGIS, U.S. Fish and Wildlife online system Information for Planning and Conservation (IPaC) – Refer to Attachment K.

For criterion B, provide the Tracking Number from the other operator’s notification of permit authorization: INSERT AUTHORIZATION TRACKING NUMBER FROM OTHER OPERATOR'S NOTIFICATION LETTER/EMAIL

Provide a brief summary of the basis used by the other operator for selecting criterion A, B, C, D, E, or F: INSERT TEXT HERE

For criterion C, provide the following information:

INSERT LIST OF FEDERALLY-LISTED SPECIES OR FEDERALLY-DESIGNATED CRITICAL HABITAT LOCATED IN YOUR ACTION AREA

INSERT DISTANCE BETWEEN YOUR SITE AND THE LISTED SPECIES OR CRITICAL HABITAT (in miles)

Also, provide a brief summary of the basis used for determining that your site’s discharges and discharge-related activities are not likely to adversely affect listed species or critical habitat: INSERT TEXT HERE

For criterion D, E, or F, attach copies of any letters or other communication between you and the U.S. Fish & Wildlife Service or National Marine Fisheries Service concluding consultation or coordination activities. INSERT COPIES OF LETTERS OR OTHER COMMUNICATIONS HERE


17

3.2 Historic Preservation

Appendix E (of the CGP), Step 1

Do you plan on installing any of the following stormwater controls at your site? Check all that apply below, and proceed to Appendix E, Step 2.

Dike

Berm

Catch Basin

Pond

Stormwater Conveyance Channel (e.g., ditch, trench, perimeter drain, swale, etc.)

Culvert

Other type of ground-disturbing stormwater control: Water Quality Inlets, Water Quality Structures, Jellyfish Structure, Outlet Control Structure, Subsurface Infiltration System, Drain Manhole, Trench Drain, etc…

If you will not be installing any ground-disturbing stormwater controls, no further documentation is required for Section 3.2 of the Template.

Appendix E, Step 2

If you answered yes in Step 1, have prior cultural resource surveys or other evaluations determined that historic properties do not exist, or that prior disturbances at the site have precluded the existence of historic properties? YES NO

If yes, provide documentation of the basis for your determination. If no, proceed to Appendix E, Step 3.

Appendix E, Step 3

If you are installing any stormwater controls that require subsurface earth disturbance, you must determine if these activities will have an effect on historic properties. This assessment may be based on historical sources, knowledge of the area, an assessment of the types of earth-disturbing activities you are engaging in, considerations of any controls and/or management practices you will adopt to ensure that your stormwater control related earth-disturbing activities will not have an effect on historic properties, and any other relevant factors.

Does your determination demonstrate that earth disturbances related to the installation of your stormwater controls will have no effect on historic properties? YES NO

If yes, provide documentation of the basis for your determination. If no, proceed to Appendix E, Step 4.

Appendix E, Step 4

If you are installing any stormwater controls that require subsurface earth disturbance and you have not satisfied the conditions in Steps 1-3, you must contact and consult with the appropriate historic preservation authorities including the State Historic Preservation Officer (SHPO), Tribal Historic Preservation Office (THPO), or other tribal representative (whichever applies). Your request should include the information outlined in Appendix E of the CGP.

Did SHPO, THPO, or another tribal representative respond to you within 15 calendar days after their receipt to indicate whether the subsurface earth disturbances caused by the installation of stormwater controls affect historic properties? YES NO

If no, no further documentation is required for Section 3.2 of the Template.


18

If yes, describe the nature of their response:

Written indication that adverse effects to historic properties from the installation of stormwater controls can be mitigated by agreed upon actions. INSERT COPIES OF LETTERS, EMAILS, OR OTHER COMMUNICATION BETWEEN YOU AND THE APPLICABLE SHPO, THPO, OR OTHER TRIBAL REPRESENTATIVE

No agreement has been reached regarding measures to mitigate effects to historic properties from the installation of stormwater controls. INSERT COPIES OF LETTERS, EMAILS, OR OTHER COMMUNICATION BETWEEN YOU AND THE APPLICABLE SHPO, THPO, OR OTHER TRIBAL REPRESENTATIVE

Other: INSERT COPIES OF LETTERS, EMAILS, OR OTHER COMMUNICATION BETWEEN YOU AND THE APPLICABLE SHPO, THPO, OR OTHER TRIBAL REPRESENTATIVE

If within 15 days of receipt of your request the applicable SHPO, THPO, or other tribal representative responds with a request for additional information or for further consultation, you must comply with this request and proceed to Step 5.

Appendix E, Step 5

If, following your discussions with the appropriate historic preservation authorities in Step 4, the applicable SHPO, THPO, or tribal representative requests additional information or further consultation, you must respond with such information or consult to determine impacts to historic properties that may be caused by the installation of stormwater controls on your site and appropriate measures for treatment or mitigation of such impacts. If as a result of your discussions with the applicable SHPO, THPO, or tribal representative, you enter into, and comply with, a written agreement regarding treatment and/or mitigation of impacts on your site, then you may indicate this on your NOI, and no further screening steps are necessary.

If, however, agreement on an appropriate treatment or mitigation plan cannot be reached between you and the SHPO, THPO, or other tribal representative within 30 days of your response to the SHPO, THPO, or other tribal representative’s request for additional information or further consultation, you may submit your NOI, but you must indicate that you have not negotiated measures to avoid or mitigate such effects. You must also include in your SWPPP the following documentation:

1. Copies of any written correspondence between you and the SHPO, THPO, or other tribal representative; and

2. A description of any significant remaining disagreements as to mitigation measures between you and the SHPO, THPO, or other tribal representative.

After submitting your NOI, and during the 14-day waiting period, the SHPO, THPO, ACHP, or other tribal representative may request that EPA place a hold on authorization based upon concerns regarding potential adverse effects to historic properties. EPA, in coordination with the ACHP, will evaluate any such request and notify you if any additional measures to address adverse effects to historic properties are necessary.

3.3 Safe Drinking Water Act Underground Injection Control Requirements

Do you plan to install any of the following controls? Check all that apply below.


19

Infiltration trenches (if stormwater is directed to any bored, drilled, driven shaft or dug hole that is deeper than its widest surface dimension, or has a subsurface fluid distribution system);

Commercially manufactured pre-cast or pre-built proprietary subsurface detention vaults, chambers, or other devices designed to capture and infiltrate stormwater flow; and

Drywells, seepage pits, or improved sinkholes (if stormwater is directed to any bored, drilled, driven shaft or dug hole that is deeper than its widest surface dimension, or has a subsurface fluid distribution system)

If one or more of the above apply, then, INSERT COPIES OF LETTERS, EMAILS, OR OTHER COMMUNICATION BETWEEN YOU AND THE STATE AGENCY OR EPA REGIONAL OFFICE


20

SECTION 4: EROSION AND SEDIMENT CONTROLS REQUIREMENTS

To pick an inspection schedule for all of section 4: • If your site discharges to a water body with sediment or nutrient impairments Once every 7 days and within

24 hours of a storm event of 0.25 inches or greater (this includes the occurrence of runoff from snow melt

sufficient to cause a discharge).

• If your site discharges to a water body with a Tier 2, 2.5, or 3 water Once every 7 days and within 24 hours

of a storm event of 0.25 inches or greater (this includes the occurrence of runoff from snow melt sufficient to

cause a discharge).

• If your site does not discharge to any of the above Conduct a site inspection once very seven (7) days or

conduct a site inspection once every 14 days and within 24 hours of a storm event of 0.25 inches or greater.

(this includes the occurrence of runoff from snow melt sufficient to cause a discharge).

To pick a Site Stabilization requirement: • If your site discharges to a water body with sediment or nutrient impairments Initiate stabilization measures

where construction activities have permanently ceased or will be temporarily inactive for 14 or more days.

Complete stabilization as soon as practicable but no later than 7 days after stabilization has been initiated.

• If your site discharges to a water body classified as a Tier 2, 2.5, or 3 water Initiate stabilization measures



• If your site is 5 acres or less (includes sites disturbing more than 5 acres’ total over the course of a project,

but that limit disturbance at any one time to five acres or less) Initiate stabilization measures where

construction activities have permanently ceased or will be temporarily inactive for 14 or more days. Complete

the installation of stabilization measures as soon as practicable but no later than 14 calendar days after

stabilization has been initiated.

• If your site is more than 5 acres and proposes greater than 5 acres of disturbance Initiate stabilization

measures where construction activities have permanently ceased or will be temporarily inactive for 14 or more

days. Complete stabilization as soon as practicable but no later than 7 days after stabilization has been

initiated.

If You have any additional controls to use in any of the following sections, use the format below. Control # X

• BMP Description: Description of control to be installed.

• Installation Schedule: Approximate date of installation

• Inspection Schedule: Pick Inspection schedule from above.

• Maintenance: Ensure that all stormwater controls remain in effective condition as decribed in part 2.1.4 of the CGP.

• Responsible Staff: Construction Manager and Site Contractor. Section 4 of this document describes the stormwater controls that will be implemented throughout construction. The operator must install and maintain all stormwater controls in compliance with Parts 2.2 and 2.3 of the CGP. The operator must install stormwater controls by the time construction activity in any givern portion of the site begins. The stormwater controls shall be designed and installed in accordance with good engineering practices and applicable design specifications. Specifications titled “312500- Erosion and Sedimentation Controls,” dated ******* and prepared by Nitsch Engineering and details titled “Erosion and Sedimentation Control Details,” dated ******* and prepared by Nitsch Engineering have been provided to the contractor under separate cover.

4.1 Natural Buffers or Equivalent Sediment Controls

Delete Sections/ Yellow directions Text that are not applicable to your project.


21

Buffer Compliance Alternatives

Are there any surface waters within 50 feet of your project’s earth disturbances? YES NO

(Note: If no, no further documentation is required for Part 4.1 in the SWPPP Template. Continue to Part 4.2.)

Check the compliance alternative that you have chosen:

I will provide and maintain a 50-foot undisturbed natural buffer.

(Note [1]: You must show the 50-foot boundary line of the natural buffer on your site map.)

(Note [2]: You must show on your site map how all discharges from your construction disturbances through the natural buffer area will first be treated by the site’s erosion and sediment controls. Also, show on the site map any velocity dissipation devices used to prevent erosion within the natural buffer area.)

I will provide and maintain an undisturbed natural buffer that is less than 50 feet and is supplemented by additional erosion and sediment controls, which in combination achieves the sediment load reduction equivalent to a 50-foot undisturbed natural buffer.

(Note [1]: You must show the boundary line of the natural buffer on your site map.)

(Note [2]: You must show on your site map how all discharges from your construction disturbances through the natural buffer area will first be treated by the site’s erosion and sediment controls. Also, show on the site map any velocity dissipation devices used to prevent erosion within the natural buffer area.)

• INSERT WIDTH OF NATURAL BUFFER TO BE RETAINED

• INSERT EITHER ONE OF THE FOLLOWING:

(1) THE ESTIMATED SEDIMENT REMOVAL FROM A 50-FOOT BUFFER USING APPLICABLE TABLES IN APP. K. OF THE CGP INCLUDE INFORMATION ABOUT THE BUFFER VEGETATION AND SOIL TYPE THAT PREDOMINATE AT YOUR SITE

OR

(2) IF YOU CONDUCTED A SITE-SPECIFIC CALCULATION FOR THE ESTIMATED SEDIMENT REMOVAL OF A 50-FOOT BUFFER, PROVIDE THE SPECIFIC REMOVAL EFFICIENCY, AND INFORMATION YOU RELIED UPON TO MAKE YOUR SITE-SPECIFIC CALCULATION.

• INSERT DESCRIPTION OF ADDITIONAL EROSION AND SEDIMENT CONTROLS TO BE USED IN COMBINATION WITH NATURAL BUFFER AREA

• INSERT THE FOLLOWING INFORMATION:

a. (1) SPECIFY THE MODEL OR OTHER TOOL USED TO ESTIMATE SEDIMENT LOAD REDUCTIONS FROM THE COMBINATION OF THE BUFFER AREA AND ADDITIONAL EROSION AND SEDIMENT CONTROLS INSTALLED AT YOUR SITE, AND

b. (2) INCLUDE THE RESULTS OF CALCULATIONS SHOWING THAT THE COMBINATION OF YOUR BUFFER AREA AND THE ADDITIONAL EROSION AND SEDIMENT CONTROLS INSTALLED AT YOUR SITE WILL MEET OR EXCEED THE SEDIMENT REMOVAL EFFICIENCY OF A 50-FOOT BUFFER

It is infeasible to provide and maintain an undisturbed natural buffer of any size, therefore I will implement erosion and sediment controls that achieve the sediment load reduction equivalent to a 50-foot undisturbed natural buffer.

• INSERT RATIONALE FOR CONCLUDING THAT IT IS INFEASIBLE TO PROVIDE AND MAINTAIN A NATURAL BUFFER OF ANY SIZE

• INSERT EITHER ONE OF THE FOLLOWING:


22

(1) THE ESTIMATED SEDIMENT REMOVAL FROM A 50-FOOT BUFFER USING APPLICABLE TABLES IN APP. K OF THE CGP, ATTACHMENT 1. INCLUDE INFORMATION ABOUT THE BUFFER VEGETATION AND SOIL TYPE THAT PREDOMINATE AT YOUR SITE

OR

(2) IF YOU CONDUCTED A SITE-SPECIFIC CALCULATION FOR THE ESTIMATED SEDIMENT REMOVAL OF A 50-FOOT BUFFER, PROVIDE THE SPECIFIC REMOVAL EFFICIENCY, AND INFORMATION YOU RELIED UPON TO MAKE YOUR SITE-SPECIFIC CALCULATION.

• INSERT DESCRIPTION OF ADDITIONAL EROSION AND SEDIMENT CONTROLS TO BE USED IN COMBINATION WITH NATURAL BUFFER AREA

• INSERT THE FOLLOWING INFORMATION:

a. (1) SPECIFY THE MODEL OR OTHER TOOL USED TO ESTIMATE SEDIMENT LOAD REDUCTIONS FROM THE EROSION AND SEDIMENT CONTROLS INSTALLED AT YOUR SITE, AND

b. (2) INCLUDE THE RESULTS OF CALCULATIONS SHOWING THAT THE ADDITIONAL EROSION AND SEDIMENT CONTROLS INSTALLED AT YOUR SITE WILL MEET OR EXCEED THE SEDIMENT REMOVAL EFFICIENCY OF A 50-FOOT BUFFER

I qualify for one of the exceptions in Appendix G Section G.2.2 of the CGP. (If you have checked this box, provide information on the applicable buffer exception that applies, below.)

Buffer Exceptions Which of the following exceptions to the buffer requirements applies to your site?

Construction is approved under a CWA Section 404 permit. INSERT DESCRIPTION OF ANY EARTH DISTURBANCES THAT WILL OCCUR WITHIN THE BUFFER AREA

(Note [1]: If this exception applies, no further documentation is required for Section 4.1 of this Template.)

(Note [2]: This exception only applies to the limits of disturbance authorized under the Section 404 permit, and does not apply to any upland portion of the construction project.)

Buffer disturbances will occur for the construction of a water-dependent structure or water access area (e.g., pier, boat ramp, and trail). INSERT DESCRIPTION OF ANY EARTH DISTURBANCES THAT WILL OCCUR WITHIN THE BUFFER AREA

(Note [1]: If this exception applies, no further documentation is required for Section 4.1 of the Template.)

There is no discharge of stormwater to the waters of the U.S. through the area between the disturbed portions of the site and any waters of the U.S. located within 50 feet of your site.

(Note: If this exception applies, no further documentation is required for this section of the Template.)

No natural buffer exists due to preexisting development disturbances that occurred prior to the initiation of planning for this project.

(Note (1): If this exception applies, no further documentation is required for this section of the Template.)

(Note (2): Where some natural buffer exists but portions of the area within 50 feet of the surface water are occupied by preexisting development disturbances, you must still comply with the one of the CGP Part 2.1.2.1.a compliance alternatives.)

For a “linear construction site” (defined in Appendix A of the CGP), site constraints (e.g., limited right-of-way) make it infeasible for me to meet any of the CGP Part G.2.1 compliance alternatives. INCLUDE DOCUMENTATION HERE OF THE FOLLOWING: (1) WHY IT IS INFEASIBLE FOR YOU TO MEET ONE OF THE BUFFER COMPLIANCE ALTERNATIVES, AND (2) BUFFER WIDTH RETAINED AND/OR SUPPLEMENTAL EROSION AND SEDIMENT CONTROLS TO TREAT DISCHARGES TO THE SURFACE WATER


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The project qualifies as “small residential lot” construction (defined in Part 2.1.2.1.e.iv and in Appendix A of the CGP). Insert information regarding how you complied with the “small residential lot” compliance alternative in Part G.3 of Appendix G of the CGP.

4.2 Perimeter Controls General The site will be enclosed by a temporary construction fence as shown on the Erosion and Sedimentation Control Plan in Attachment A. Construction gates will be located at the entrance to the site as shown on the Erosion and Sedimentation Control Plan and all entrances will have stabilized construction entrances. All gates and entrances to the site will be secured during non-working hours. The areas of the site that will receive pollutant discharges will be surrounded by a Specific Perimeter Control listed below as shown on the Erosion and Sedimentation Control Plan in Attachment A. Sediment tracked offsite must be removed by the end of the same workday. Specific Perimeter Controls Perimeter Control # 1

• BMP Description: Silt Fence.

• Installation Schedule: Prior to the Start of Construction.

• Inspection Schedule: Once every 7 days and within 24 hours of a storm event 0.25” or greater. OR Once every 14 days and within 24 hours of a storm event 0.25” or greater.

• Maintenance: Ensure that all stormwater controls remain in effective condition as described in part 2.1.4 of the CGP. Remove any sediment before it has accumulated to one-half of the above-ground height of any perimeter control.

• Responsible Staff: Construction Manager and Site Contractor(s). Perimeter Control # 2

• BMP Description: Silt Fence with Wattles.




• Responsible Staff: Construction Manager and Site Contractor(s). Perimeter Control # 3

• BMP Description: Super Silt Fence.




• Responsible Staff: Construction Manager and Site Contractor(s).


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Perimeter Control # 4

• BMP Description: Wattles.


• Inspection Schedule: Once every 7 days and within 24 hours of a storm event 0.25” or greater. OR Once every days and within 24 hours of a storm event 0.25” or greater.



Perimeter Control # 5

• BMP Description: Silt Fence with Straw Bales.

• Installation Schedule: Prior to the Start of Construction and/or immediately after stockpile is established.


• Maintenance: Ensure that all stormwater controls remain in effective condition as decribed in part 2.1.4 of the CGP. Remove any sediment before it has accumulated to one-half of the above-ground height of any perimeter control.


4.3 Sediment Track-Out

General Gates will be located as shown on the Erosion and Sedimentation Control Plan in Attachment A to allow for construction vehicle access. Construction access points will have a stabilized construction entrance station or wheel wash station to minimize the track-out of sediment onto off-site streets, other paved areas, and sidewalks from vehicles exiting the construction site. Where sediment has been tracked out from your site onto paved roads, sidewalks, or other paved areas outside of your site, remove the deposited sediment by the end of the same business day in which the track-out occurs or by the end of the next business day if track-out occurs on a non-business day. Remove the track-out by sweeping, shoveling, or vacuuming these surfaces, or by using other similarly effective means of sediment removal. You are prohibited from hosing or sweeping tracked out sediment into any stormwater conveyance, storm drain inlet, or water of the U.S. Specific Track-Out Controls Track-Out Control # 1

• BMP Description: Street Sweeping.

• Installation Schedule: Start of construction.

• Inspection Schedule: The areas adjacent to the site should be inspected daily to determine if street sweeping is required.

• Responsible Staff Construction Manager and Site Contractor(s). Track-Out Control # 2

• BMP Description: Stabilized Construction Entrance.


• Inspection Schedule: Once every 7 days and within 24 hours of a storm event 0.25” or


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greater. OR Once every 14 days and within 24 hours of a storm event 0.25” or greater.

• Maintenance: Ensure that all stormwater controls remain in effective condition as described in part 2.1.4 of the CGP.

• Responsible Staff: Construction Manager and Site Contractor(s). Track-Out Control # 3

• BMP Description: Wheel Wash Station.



• Maintenance: Ensure that all stormwater controls remain in effective. condition as described in part 2.1.4 of the CGP(s). The operator must provide an effective means of minimizing the discharge of pollutants from equipment and vehicle washing, wheel wash water, and other types of wash waters. The operator must ensure there is no discharge of soaps, solvents, or detergents in equipment and vehicle wash water. For storage of soaps, detergents, or solvents, the operator shall provide either a cover to minimze the exposure of these detergents to precipitation and to stormwater, or a similarily effective means designed to minimze discharge of pollutants from these areas.

• Responsible Staff: Construction Manager and Site Contractor.

4.4 Stockpiled Sediment or Soil

General All soil stockpiles will be located outside of any natural buffers and away from existing and proposed catch basins and area drains and outside of proposed infiltration system footprints. A sediment barrier shall be installed along all downgradient perimeter areas. Examples of sediment barriers include silt fence, super silt fence, or wattles. You are prohibited from hosing down or sweeping soil or sediment accumulated on pavement or other impervious surfaces into any stormwater conveyance, storm drain inlet, or water of the U.S.

For stockpiles that will be unused for 14 or more days, a cover such as a tarp or blown straw shall be provided or temporary stabilization should be provided (consistent with Part 2.2.14 of the CGP). Specific Stockpile Controls Stockpile Control # 1

• BMP Description: Silt Fence.

• Installation Schedule: Immediately after stockpile is established.




Stockpile Control # 2


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• BMP Description: Wattles.




Remove any sediment before it has accumulated to one-half of the above-ground height of any perimeter control.



• BMP Description: Tarp.

• Installation Schedule: When stockpile will remain inactive for 14 or more calendar days.






• BMP Description: Straw Bales.







• BMP Description: Blown Straw.







• BMP Description: Hydroseeding.


• Inspection Schedule: Once every 7 days and within 24 hours of a storm event 0.25” or


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greater. OR Once every 14 days and within 24 hours of a storm event 0.25” or greater.




4.5 Minimize Dust General Disturbed land will be temporarily stabilized as required by the CGP. Dust will be minimized using measures including sprinkling/irrigation, vegetative cover, mulch, and/or stone. Stockpiles will be handled in accordance with section 4.4 of the SWPPP. Earth-disturbing activities are considered temporarily ceased when work will not resume for a period of 14 or more calendar days. Stabilization shall be initiated when earth-disturbing activities are temporarily or permanently ceased. Stabilization activities shall be complete within X calendar days after the initiation of soil stabilization measures. Specific Dust Controls Dust Control # 1

• BMP Description: Sprinkling/Irrigation.

• Installation Schedule: As needed throughout earthwork activities as determined by

the site contractor and construction manager.




Dust Control # 2

• BMP Description: Straw or Mulch.

• Installation Schedule: As needed throughout earthwork activities as determined by

the site contractor and construction manager. When disturbed land will remain inactive for 14 or more calendar days.




4.6 Minimize the Disturbance of Steep Slopes

General If steep slopes do not exist onsite or are not disturbed:


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Steep slopes are defined as slopes of 15% or greater in grade. No steep slopes are proposed as part of this project. The EPA notes that the requirement to minimize disturbances to steep slopes does not apply to the creation of stockpiles. If steep slopes do exist onsite and will be disturbed: Steep slopes (defined as slopes of 15% or greater in grade) are expected to be disturbed onsite. Disturbances to steep slopes will be minimized by phasing disturbances to those areas and by using stabilization practices designed to be used on steep grades. Specific Steep Slope Controls Steep Slope Control # 1

• BMP Description: Straw or Mulch.

• Installation Schedule: When disturbed land will remain inactive for 14 or more calendar days.


• Maintenance: Ensure that all stormwater controls remain in effective. condition as decribed in part 2.1.4 of the CGP.

• Responsible Staff: Construction Manager and Site Contractor(s). Steep Slope Control # 2

• BMP Description: Hydroseeding.





• BMP Description: Soil Stabilization Mats.





• BMP Description: Rip-Rap.






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4.7 Preserve Native Topsoil

Onsite native topsoil shall be preserved, unless infeasible. Preserving native topsoil is not required where the intended function of a specific area of the site dictates that the topsoil be disturbed or removed. Stockpiling topsoil at off-site locations or transferring topsoil to other locations is an example of a way to preserve native topsoil. The contractor shall perform construction sequencing such that earth materials are exposed for a minimum of time before they are covered, seeded, or otherwise stabilized.

4.8 Minimize Soil Compaction

General In areas where infiltration practices will be installed or areas of the site where final vegetative stabilization will occur, soil compaction shall be minimized. This includes restricting vehicle access and equipment use. Areas used for post-construction infiltration shall be constructed after all ground surfaces are fully stabilized when feasible. If proposed infiltration areas are constructed prior to the site being fully stabilized, additional erosion controls shall be installed. All stockpiled and material storage areas shall be located outside of the areas proposed for post-construction infiltration. Areas of post-construction landscaping shall be constructed after all ground surface are fully stabilized. If proposed landscaped areas are constructed prior to the site being fully stabilized, additional erosion controls shall be installed. All soil stockpiles and material storage areas shall be located outside of the areas proposed for post-construction landscaping where feasible. Where this is not feasible, use techniques that rehabilitate and condition the soils as necessary to support vegetative growth prior to planting.

4.9 Storm Drain Inlets

General All existing and proposed storm drain inlets affected by construction activities should be protected using an Inlet Sediment Filter as shown on the Erosion and Sedimentation Control Plan provided in Attachment A. Clean or remove and replace the protection measures as sediment accumulates, the filter becomes clogged, and/or performance is compromised. Where there is evidence of sediment accumulation adjacent to the inlet protection measure, remove the deposited sediment by the end of the same business day in which it is found or by the end of the following business day if removal by the same business day is not feasible. Specific Storm Drain Inlet Controls Storm Drain Inlet Control # 1

• BMP Description: Inlet Sediment Filter.



• Maintenance: Ensure that all stormwater controls remain in effective. condition as decribed in part 2.1.4 of the CGP.



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Storm Drain Inlet Control # 2

• BMP Description: Inlet Protection with Gravel.

• Installation Schedule: Prior to the Start of Construction .




Storm Drain Inlet Control # 3

• BMP Description: Inlet Protection with Block and Gravel.





4.10 Minimize Erosion of Stormwater Conveyances

There are no proposed stormwater conveyance channels associated with this project. or The contractor shall minimize erosion of stormwater conveyance channels and their embankments, outlets, adjacent streambanks, slopes, and downstream waters. The contractor shall install erosion controls and velocity dissipation devices within and along the length of any stormwater conveyance channel and at any outlet to slow down runoff to minimize erosion. Stormwater Conveyance Control # 1

• BMP Description: Check Dam.

• Installation Schedule: Start of construction of stormwater conveyance channel.




Stormwater Conveyance Control # 2

• BMP Description: Sediment Trap.







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• BMP Description: Rip Rap.






• BMP Description: Grouted Rip Rap at outlets.





4.11 Sediment Basins There are no proposed sediment basins associated with this project. Or All sediment basins should be located outside of any waterbody, resource area, and buffer zones. Sediment basins shall be sized to provide storage for either the volume of runoff from a 2-year, 24-hour storm or 3,600 cubic feet per acre drained. Where feasible, outlet structures that withdraw water from the surface of the sediment basin shall be used. Erosion and velocity dissipation devices shall be installed at inlets and outlets to prevent erosion. Accumulated sediment shall be removed to maintain at least one-half of the design capacity. The basin shall be maintained so that it remains in effective operating condition. Sediment Basin Control # 1

• BMP Description: Check Dam.





Sediment Basin Control # 2

• BMP Description: Sediment Trap.





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• Responsible Staff: Construction Manager and Site Contractor(s)


• BMP Description: Rip Rap.






• BMP Description: Grouted Rip Rap at outlets.





4.12 Chemical Treatment

There are no proposed chemical treatments associated with this project. or Chemical treatment such as the use of polymers, flocculants, coagulants, or other treatment chemicals can only be applied where treated stormwater is directed to a sediment control such as a sediment basin or perimeter control before it is discharged. The sediment control should be installed before and after the chemical treatment is applied. Chemicals must be appropriately suited to the types of soils likely to be exposed during construction and present in the discharges being treated. All treatment chemicals shall be stored in leak-proof containers that are kept under storm-resistant cover and surrounded by secondary containment structures, or provide equivalent measures designed and maintained to minimize potential discharges of treatment chemicals in stormwater or by any other means. The contractor shall have a spill kit available onsite and ensure personnel are available to respond expeditiously in the event of a leak or spill. Chemicals shall be used in accordance with good engineering practices and specifications of the chemical provider/supplier. Any departures from their specifications shall be documented in the SWPPP. All persons who handle and use treatment chemicals on site shall be provided with appropriate, product-specific training which, among other things, must include proper dosing requirements. Perform additional measure specified by the EPA Regional Office for the authorized use of cationic chemicals.


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4.13 Dewatering Practices

Dewatering isn’t expected to occur onsite. Or Dewatering will occur in a way that minimizes the discharge of pollutants in ground water or accumulated stormwater that is removed from excavations, trenches, foundations, vaults, or other similar points of accumulation. Dewatering water shall be treated in compliance with Section 2.4 of the CGP and water with visible floating solids or foam may not be discharged. Any applicable permits shall be obtained from local permitting authorities. Dewatering Control # 1

• BMP Description: Sediment basin or Sediment Trap.





Dewatering Control # 2

• BMP Description: Sediment socks.






• BMP Description: Dewatering Tanks.


• Inspection Schedule: Once every 7 days and within 24 hours of a storm event 0.25” or greater. OR Once every 14 days and within 24 hours of a storm event 0.25” or greater and as required by the manufacturer.




• BMP Description: Filtration Systems.


• Inspection Schedule: Once every 7 days and within 24 hours of a storm event 0.25” or greater. OR Once every 14 days and within 24 hours of a storm event 0.25” or greater and as required by the manufacturer.




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4.14 Other Stormwater Controls

Any changes in construction activity that that include means of stormwater control not included in this document will be identified, the SWPPP will be amended, and the appropriate erosion and sedimentation controls will be implemented.

4.15 Site Stabilization

To pick a Site Stabilization requirement: • If your site discharges to a water body with sediment or nutrient impairments Initiate stabilization measures



• If your site discharges to a water body classified as a Tier 2, 2.5, or 3 water Initiate stabilization measures



• If your site is 5 acres or less (includes sites disturbing more than 5 acres’ total over the course of a project,

but that limit disturbance at any one time to five acres or less) Initiate stabilization measures where

construction activities have permanently ceased or will be temporarily inactive for 14 or more days. Complete

the installation of stabilization measures as soon as practicable but no later than 14 calendar days after

stabilization has been initiated.

• If your site is more than 5 acres and proposes greater than 5 acres of disturbance Initiate stabilization

measures where construction activities have permanently ceased or will be temporarily inactive for 14 or more

days. Complete stabilization as soon as practicable but no later than 7 days after stabilization has been

initiated.

Initiate the installation of stabilization measures immediately in any areas of exposed soil where construction activities have permanently ceased or will be temporarily inactive for 14 or more calendar days. Complete the installation of stabilization measures as soon as practicable, but no later than X calendar days after stabilization has been initiated. Site Stabilization Practice #1

Vegetative Non-Vegetative Temporary Permanent

• BMP Description: Soil Stabilization Mat.

• Installation Schedule: As/if required.

• Maintenance and Inspection: Once every 7 days and within 24 hours of a storm event 0.25” or greater. OR Once every 14 days and within 24 hours of a storm event 0.25” or greater.


Site Stabilization Practice #2

Vegetative Non-Vegetative Temporary Permanent

• BMP Description: Temporary Seeding.

• Installation Schedule: As/if required.


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• Maintenance and Inspection: Once every 7 days and within 24 hours of a storm event 0.25” or greater. OR Once every 14 days and within 24 hours of a storm event 0.25” or greater.



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SECTION 5: POLLUTION PREVENTION STANDARDS

5.1 Potential Sources of Pollution

Potential sources of sediment to stormwater runoff:

• Stockpiles and construction staging

• Clearing and grubbing operations

• Grading and site excavation

• Topsoil stripping

• Landscape operations

• Soil tracking offsite from construction vehicles

• Runoff from unstabilized areas

• Construction debris

Potential pollutants and sources, other than sediment, to stormwater runoff:

• Combined Staging Area – fueling activities, equipment maintenance, sanitary facilities, and hazardous waste storage

• Materials Storage Area – building materials, solvents, adhesives, paving materials, paints, aggregates, trash, etc.

• Construction Activity-paving, curb installation, concrete pouring, and building construction

Staging areas are shown on the Erosion and Sedimentation Control Plan provided in Attachment A.


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Construction Site Pollutants

Pollutant-Generating Activity

Pollutants or Pollutant Constituents

(that could be discharged if exposed to stormwater)

Location on Site (or reference SWPPP site map

where this is shown)

Pesticides (insecticides, fungicides, herbicides,

rodenticides)

Chlorinated hydrocarbons, organophosphates, carbonates,

arsenic

Herbicides used for noxious weed control

Fertilizers Nitrogen, phosphorous Newly seeded areas

Plaster Calcium sulphate, calcium

carbonate, sulfuric acid Building construction

Cleaning Solvents Perchloroethylene, methylene

chloride, trichloroethylene, petroleum distillates

No equipment cleaning allowed in project limits

Asphalt Oil, petroleum distillates Streets and parking lots

Concrete Limestone, sand pH, chromium Curb and gutter, sidewalk,

building construction

Glue, Adhesives Polymers, epoxies Building construction

Paints Metal oxides, Stoddard solvent, talc, calcium carbonate, arsenic

Building construction

Curing compounds Naphtha Curb and gutter, building

construction

Wood preservatives Stoddard solvent, petroleum distillates, arsenic, copper,

chromium

Timber pads, bracing, building construction

Hydraulic Oils/fluids Mineral oil Leaks/broken hoses from

equipment

Gasoline Benzene, ethyl benzene, toluene, xylene, MTBE

Secondary containment/staging area

Diesel Fuel Petroleum distillate, oil & grease,

naphthalene, xylenes Secondary containment/staging

area

Kerosene Coal oil, petroleum distillates Secondary containment/staging

area

Antifreeze/coolant Ethylene glycol, propylene

glycol, heavy metals (copper, lead, zinc)

Leaks or broken hoses from equipment

Sanitary toilets Bacteria, parasites, and viruses Staging area


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5.2 Spill Prevention and Response

BMP Description: Spill kit, vehicle washing, silt sack catch basin protection, silt fence Installation Schedule: Start of construction activity Maintenance and Inspection: Minimum weekly & as necessary Responsible Staff: Construction Manager and Site Contractor

• Major vehicle maintenance onsite is prohibited

• Re-fueling of vehicles within 25 feet of a drainage structure is prohibited

• Spill kit shall be kept onsite consisting of:

- Gloves

- Absorbent mats

- Drip pan

Spill Prevention and Control Plan

• Refer to contractor’s Spill Plan.

• Manufacturers’ recommended spill control methods will be posted onsite and site personnel will be made aware of the requirements.

• Cleanup supplies will be kept onsite in a materials storage area. This equipment will include: goggles, brooms, dustpans, mops, rags, gloves, oil absorbent, sawdust, plastic and metal trash cans, and other materials and supplies specifically designated for cleanup.

• All spills will be immediately cleaned up after discovery.

• The spill area will be well ventilated.

• Cleanup personnel will wear suitable protective clothing.

• Spills of toxic and/or hazardous material will be reported to state, local, and Federal authorities, as required by law. Spills shall also be reported immediately to the owner.

• A spill incident report will be filed detailing the amount and extent of the spill, material(s) involved, and effectiveness of the cleanup. This report will be on file at the Construction Manager/Site Contractor office, as well as kept onsite in the field office. A copy shall also be filed with the Hazard Communication Coordinator (HCC). Contractor should indicate if they have a Hazard Communication Coordinator or who spills should be reported to.

The Construction Manager/Site Contractor will designate someone onsite that will serve as the Spill Cleanup Coordinator. At least two other personnel will be designated as alternate spill coordinators. All spill control personnel will be trained in spill prevention, control, and cleanup. The names of the responsible personnel will be posted at the jobsite office of the Construction Manager/ Site Contractor.

5.3 Fueling and Maintenance of Equipment or Vehicles

General

Minor vehicle and equipment emergency maintenance can be performed onsite away from drainage structures. Major vehicle and equipment maintenance must be performed offsite. Equipment/vehicle storage areas and any onsite fuel tanks will be inspected weekly and after storm events. Equipment and vehicles will be inspected for leaks, equipment damage, and other service problems on each day of use. Any leaks will be repaired immediately or the equipment/vehicle will be removed from the site.

Minor vehicle and equipment emergency maintenance shall occur when a vehicle cannot be safely removed from the site. The vehicle should be repaired so it can be taken off-site so that the rest of the maintenance can occur.

Major vehicle maintenance onsite is prohibited. Re-fueling or maintenance of vehicles within 25 feet of a drainage structure shall be prohibited. Drip pans, drip cloths, or absorbent pads should be used when replacing spent fluids. The fluids should be collect and stored prior to being disposed of offsite.


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Specific Pollution Prevention Practice #1

• BMP Description: Spill Kit.

• Installation Schedule: Onsite throughout construction.


Specific Pollution Prevention Practice #1

• BMP Description: Drip Pans, Drip Cloths, Absorbent Pads.

• Installation Schedule: Onsite throughout construction.


5.4 Washing of Equipment and Vehicles

General

Vehicle and equipment washout areas shall be constructed by the contractor so that no untreated water enters the storm drain system. Soaps, detergents, or solvents must be stored in a way to prevent these detergents from coming into contact with rainwater, or a similarly effective means designed to prevent the discharge of pollutants from these areas. Specific Pollution Prevention Practices Pollution Prevention Practice # 1

• BMP Description: Designated vehicle/equipment washing areas


• Inspection Schedule: Once every 7 days and within 24 hours of a storm event 0.25” or greater. OR Once every 14days and within 24 hours of a storm event 0.25” or greater.

• Responsible Staff: Construction Manager and Site Contractor

Pollution Prevention Practice # 2

• BMP Description: Spill kit, vehicle washing, straw bale catch basin protection, silt

fence

• Installation Schedule: Start of construction activity


• Responsible Staff: Construction Manager and Site Contractor

5.5 Storage, Handling, and Disposal of Construction Products, Materials, and Wastes

5.5.1 Building Products

General The contractor will recycle all construction materials possible. For materials that cannot be recycled, solid waste will be disposed of in accordance with DEP Regulations for Solid Waste Facilities, 310 CMR 10.00. Any building materials required to be stored onsite will be stored at a combined staging and materials storage area as shown on the CMP. Larger items will be elevated by appropriate methods to minimize contact with runoff. The storage area will be inspected weekly and after storm events. It will be kept clean, organized, and equipped with appropriate cleaning supplies.


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Building product usage shall follow the following good housekeeping BMPs:

• The Responsible Staff: Construction Manager or Site Contractor representative will inspect daily for inspection of the work area to ensure proper management of waste materials.

• Store only enough material onsite required for that job as to satisfy current construction needs.

• Store required materials in tightly lidded containers under cover.

• Store materials in original containers with clearly legible labels.

• Separate and store materials apart from each other.

• Do not mix materials unless specifically in accordance with manufacturers’ recommendations.

• Use all products from a container before disposing of the container.

• Follow manufacturers’ instructions for handling, storage, and disposing of all materials.

• All materials shall be stored in an area to prevent the discharge of pollutants from building products.

Specific Pollution Prevention Practices Pollution Prevention Practice # 1

• BMP Description: Perimeter Protection control around Stockpiles.

• Installation Schedule: Start of construction/ Immediately after stockpile is

established.



• Responsible Staff: Construction Manager and Site Contractor(s). 5.5.2 Pesticides, Herbicides, Insecticides, Fertilizers, and Landscape Materials

• In storage areas, provide either (1) cover to minimize the exposure of these chemicals to precipitation and to stormwater or (2) a similarly effective means designed to minimize the discharge of pollutants from these areas.

• Comply with all application and disposal requirements included on the registered pesticide, herbicide, insecticide, and fertilizer label.

5.5.3 Diesel Fuel, Oil, Hydraulic Fluids, Other Petroleum Products, and Other Chemicals

General

• Only skilled personnel in a designated area will perform fueling of vehicles onsite.

• Vehicles used onsite will be monitored for fuel and oil leaks.

• Vehicles used onsite will be maintained in good working order.

• Asphalt substances will be applied in accordance with manufacturers’ recommendations.

• The use of petroleum products as a release agent for asphalt transport trucks is prohibited.

• Vehicle fueling will only be done in vehicle fueling areas located by the contractor. See section 5.3 of the SWPPP.

• The contractor shall be responsible for locating the fuel storage and re-fueling area onsite to minimize disturbance to construction activates and site area.

• Construction equipment not in active use for 5 minutes or more will be turned off.


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5.5.4 Hazardous or Toxic Waste (Note: Examples include paints, solvents, petroleum-based products, wood preservatives, additives, curing compounds, acids.)

General

• Keep products in their original containers.

• Original container labels should be clearly visible.

• Material safety data sheets will be kept onsite and be available.

• Follow all state, local, and Federal regulations regarding the handling, use, storage, and disposal of hazardous material.

Paints:

• All paint containers will be tightly sealed when not in use.

• Remove excess paint in original labeled containers from the jobsite.

• Paint will not be disposed of onsite. Remove excess paint material from the site and legally dispose of.

• Paint shall not be disposed of in the storm drain system.


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5.5.5 Construction and Domestic Waste General The contractor will manage domestic waste onsite. The contractor will provide waste containers of sufficient size and number to contain construction and domestic wastes. The waste container lids will be kept closed when not in use and lids will be closed at the end of the business day for those containers that are actively used throughout the day. For waste containers that do not have lids, provide either a cover or a similarly effective means designed to minimize discharge of pollutants. Clean up immediately if containers overflow. Pollution Prevention Practice # 1

• BMP Description: Dumpster.


• Maintenance and Inspection: Weekly and covered daily.



• BMP Description: Litter/debris pick-up.


• Maintenance and Inspection: Daily.


5.5.6 Sanitary Waste All sanitary waste portable toilets shall be positioned so that they are secure and will not be tipped or knocked over, and located away from any stormwater inlets or conveyances. Pollution Prevention Practice # 1

• BMP Description: Porta John.


• Maintenance and Inspection: As manufacturer requires.


5.6 Washing of Applicators and Containers used for Paint, Concrete, or Other Materials

General Washing of applicators and containers used for paint, concrete, or other materials shall follow the following good housekeeping BMPs:

• An effective means of eliminating the discharge of water from the washout and cleanout of stucco, paint, concrete, form release oils, curing compounds, and other construction materials.

• All washwater must be directed into a leak-proof container or leak-proof pit. The container or pit must be designed so that no overflows can occur due to inadequate sizing or precipitation.

• Washout and cleanout wastes should be handled as follows:

― Do not dump liquid wastes into storm sewers.

― Dispose of liquid wastes in accordance with applicable requirements.

― Remove and dispose of hardened concrete waste consistent with the handling of other construction wastes.

• Locate any washout or cleanout activities as far away as possible from surface waters and stormwater inlets or conveyances, and to the extent practicable, designate areas to be used for these activities and conduct such activities only in these areas.


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• BMP Description: Designated applicator and container washing areas.


• Maintenance and Inspection: Daily.


5.7 Fertilizers General If fertilizer is required onsite, installation will follow the following guidelines:

• Fertilizers will be used at the application rates called for in the specifications for the project.

• Once applied, fertilizer will be worked into the soil to minimize wash off from irrigation and stormwater.

• Fertilizer will be stored under cover.

• The contents of partially used fertilizer bags will be transferred to re-sealable, watertight containers clearly labeled with their contents.

• Avoid applying before heavy rains.

• Never apply to frozen ground.

• Never apply to stormwater conveyance channels with flowing water.

5.8 Other Pollution Prevention Practices

Any changes in construction activity that produce other allowable non-stormwater discharges will be identified, the SWPPP will be amended and the appropriate erosion and sedimentation controls will be implemented. Control # X

• BMP Description: Description of control to be installed.

• Installation Schedule: Approximate date of installation.

• Inspection Schedule: Pick Inspection schedule from above.




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SECTION 6: INSPECTION AND CORRECTIVE ACTION

6.1 Inspection Personnel and Procedures

Personnel Responsible for Inspections

Construction Manager Contact Person Site Contractor Contact person

(Note: All personnel conducting inspections must be considered a “qualified person.” CGP Part 4.1.1 clarifies that a “qualified person” is a person knowledgeable in the principles and practices of erosion and sediment controls and pollution prevention, who possesses the skills to assess conditions at the construction site that could impact stormwater quality, and the skills to assess the effectiveness of any stormwater controls selected and installed to meet the requirements of this permit.)

Inspection Schedule

Specific Inspection Frequency

The contractor shall inspect and maintain erosion control measures, and remove sediment therefrom, once every 7 days and within 24 hours of a storm event 0.25” or greater. OR Once every 14 days and within 24 hours of a storm event 0.25” or greater.

Rain Gauge Location:

NOAA Rain Gauge Location or Onsite Rain Gauge Location

Reductions in Inspection Frequency (if applicable):

Inspection frequency may be reduced to twice per month (no more than 14 days apart) for the first month in areas of the site where the stabilization steps outlines in Parts 2.2.14 of the CGP have been completed. After the first month, inspection frequency may be reduced to once per month. If construction activity resumes in this portion of the site at a later date, the inspection frequency immediately increases to that required in Parts 4.2 and 4.3 as applicable. You must document the beginning and ending dates of this period in the SWPPP.

Inspection frequency may be reduced to once per month and within 24 hours of the occurrence of a storm event of 0.25 inches or greater if the project is located in an arid, semi-arid, or drought-stricken area and construction is occurring during the seasonally dry period or a period in which drought is predicted to occur. If this inspection frequency is followed, you must document the beginning and ending dates of this period in the SWPPP.

Inspections can be temporarily suspended under the following conditions:

• Earth-disturbing activity is suspended due to frozen condition;

• Runoff is unlikely due to continuous frozen conditions that are likely to continue at the site for at

least three months based on historic seasonal averaged. If unexpected weather conditions

make discharges likely, the operators must immediately resume the regular inspection

schedule;

• Land disturbances have been suspended; and

• All disturbed areas of the site have been stabilized in accordance with Part 2.2.14a of the CGP.


45

Inspection frequency may be reduced to once per month under the following conditions:

• The operator is still conducting earth disturbing activities under frozen conditions;

• Runoff is unlikely due to continuous frozen conditions that are likely to continue at the site for at

least three months based on historic seasonal averages. If unexpected weather conditions

make discharges likely, the operator must immediately resume the regular inspection

schedule; and

• Except for areas in which the operator is conducting earth-disturbing activities, disturbed areas of

the site have been stabilized in accordance with Part 2.2.14a of the CGP.

Inspection Report Forms Copies of inspection reports are in Attachment D.

6.2 Corrective Action

Personnel Responsible for Corrective Actions

Contact Person, Construction Manager Company

Contact Person, Site Contractor

Corrective Action Forms A copy of the Corrective Action Form is in Attachment E.

6.3 Delegation of Authority

Duly Authorized Representative(s) or Position(s):

Construction Manager Company

Contact Person

Contact Person Title

Street Address

Town/City, State Zip Code

xxx-xxx-xxxx

Email address


46

SECTION 7: TRAINING LOG

Refer to Attachment I for a Training Log to be completed for each SWPPP training session.

Table 7-1: Documentation for Completion of Training

Name Date Training Completed


47

SECTION 8: CERTIFICATION AND NOTIFICATION

Operator – Owner’s Representative

I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gathered and evaluated the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I have no personal knowledge that the information submitted is other than true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing violations.

Name: Title:

Signature: Date:

Operator – Construction Manager

I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gathered and evaluated the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I have no personal knowledge that the information submitted is other than true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing violations.

Name: Title:

Signature: Date:


SWPPP ATTACHMENTS

Attach the following documentation to the SWPPP:

Attachment A – Site Maps

Attachment B – 2017 Construction General Permit

Attachment C – NOI and EPA Authorization Email

Attachment D – Inspection Form

Attachment E – Corrective Action Form

Attachment F – SWPPP Amendment Log

Attachment G – Subcontractor Certifications/Agreements

Attachment H – Grading and Stabilization Activities Log

Attachment I – SWPPP Training Log

Attachment J – Delegation of Authority Form

Attachment K – Endangered Species Documentation

Attachment L – Historic Preservation Documentation

Attachment M – Rainfall Gauge

Attachment N – Order of Conditions


Attachment A – Site Maps Site Maps must include the following:

a) Boundaries of the property. The map(s) in the SWPPP must show the overall boundary of the

property.

b) Locations where construction activities will occur. The map(s) in the SWPPP must show the

locations where construction activities will occur, including

i. Locations where earth-disturbing activities will occur (note any phasing), including any

demolition activities;

ii. Approximate slopes before and after major grading activities (note any steep slopes);

iii. Locations where sediment, soil, or other construction materials will be stockpiled;

iv. Any water of the U.S. crossings;

v. Designated points where vehicles will exit onto paved roads;

vi. Locations of structures and other impervious surfaces upon completion of construction;

vii. Locations of onsite and off-site construction support activity areas covered by the permit

(see Part 1.2.1.c).

c) Locations of all waters of the U.S. within and one mile downstream of the site’s discharge point.

Also identify if any are listed as impaired, or are identified as a Tier 2, Tier 2.5, or Tier 3 water.

d) Areas of federally listed critical habitats within the site and/or at discharge locations.

e) Type and extent of pre-construction cover on the site (e.g., vegetative cover, forest, pasture,

pavement, structures).

f) Drainage patterns of stormwater and authorized non-stormwater before and after major grading

activities.

g) Stormwater and authorized non-stormwater discharge locations. The permit requires the site map

to show information pertaining to discharge locations including:

i. Locations where stormwater and/or authorized non-stormwater will be discharges to

storm drain inlets; and

ii. Locations where stormwater and/or authorized non-stormwater will be discharged directly

to waters of the U.S.

h) Locations of all potential pollutant-generating activities identified in Part 7.2.3.g. The permit

requires identification in the site map of all potential pollutant-generating activities identified in

Part 7.2.3.g.

i) Locations of stormwater controls, including natural buffer areas and any shared controls utilized

to comply with this permit. The permit requires identification on the site map of the location of

stormwater control measures.

j) Locations where polymers, flocculants, or other treatment chemicals will be used and stored. The

permit requires identification on the site map of the locations where polymers, flocculants, or

other treatment chemicals will be used and stored.

Include the following if possible:

• LOCUS Map created with GIS

• USGS Map created with GIS

• Phasing Plans/Mobilization Plans/Construction Management Plans from the contractor

• Erosion and Sedimentation Control Plans


Attachment B – 2017 Construction General Permit


Attachment C – NOI and EPA Authorization e-mail


Attachment D – Inspection Form


Attachment E – Corrective Action Form


Attachment F – SWPPP Amendment Log


No. Description of the Amendment Date of Amendment

Amendment Prepared by [Name(s) and Title]


Attachment G –Subcontractor Certifications/Agreements


SUBCONTRACTOR CERTIFICATION STORMWATER POLLUTION PREVENTION PLAN

Project Number: Project Title: Operator(s): As a subcontractor, you are required to comply with the Stormwater Pollution Prevention Plan (SWPPP) for any work that you perform onsite. Any person or group who violates any condition of the SWPPP may be subject to substantial penalties or loss of contract. You are encouraged to advise each of your employees working on this project of the requirements of the SWPPP. A copy of the SWPPP is available for your review at the office trailer. Each subcontractor engaged in activities at the construction site that could impact stormwater must be identified and sign the following certification statement: I certify under the penalty of law that I have read and understand the terms and conditions of the SWPPP for the above designated project and agree to follow the practices described in the SWPPP. This certification is hereby signed in reference to the above named project: Company: Address: Telephone Number: Type of construction service to be provided: Signature: Title: Date:


Attachment H – Grading and Stabilization Activities Log

DR

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Attachment I – SWPPP Training Log


Stormwater Pollution Prevention Training Log

Project Name: Project Location: Instructor’s Name(s): Instructor’s Title(s): Course Location: Date: Course Length (hours): Stormwater Training Topic: (check as appropriate) Sediment and Erosion

Controls

Emergency Procedures

Stabilization Controls Inspections/Corrective Actions Pollution Prevention

Measures

Specific Training Objective:

Attendee Roster: (attach additional pages as necessary)

No. Name of Attendee Company

1

2

3

4

5

6

7

8

Stormwater Pollution Prevention Plan (SWPPP) Project Name

62

Attachment J – Delegation of Authority Form


63

Delegation of Authority

I, _______________________ (name), hereby designate the person or specifically described position below to be a duly authorized representative for the purpose of overseeing compliance with environmental requirements, including the Construction General Permit, at the ____________________________________ construction site. The designee is authorized to sign any reports, stormwater pollution prevention plans and all other documents required by the permit.

________________________________________ (name of person or position) ________________________________________ (company) ________________________________________ (address) ________________________________________ (city, state, zip) ________________________________________ (phone)

By signing this authorization, I confirm that I meet the requirements to make such a designation as set forth in Appendix I of EPA’s Construction General Permit (CGP), and that the designee above meets the definition of a “duly authorized representative” as set forth in Appendix I. I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gathered and evaluated the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing violations. Name: Company: Title: Signature: Date:


64

Attachment K – Endangered Species Documentation


65

Attachment L – Historic Preservation Documentation


66

Attachment M – Rainfall Gauge Recording

Use the table below to record the rainfall gauge readings at the beginning and end of each work

day. An example table follows.

Month/Year Month/Year Month/Year

Day Start time End time Day Start time End time Day Start time End time

1 1 1

2 2 2

3 3 3

4 4 4

5 5 5

6 6 6

7 7 7

8 8 8

9 9 9

10 10 10

11 11 11

12 12 12

13 13 13

14 14 14

15 15 15

16 16 16

17 17 17

18 18 18

19 19 19

20 20 20

21 21 21

22 22 22

23 23 23

24 24 24

25 25 25

26 26 26

27 27 27

28 28 28

29 29 29

30 30 30

31 31 31


67

Attachment N – Order of Conditions


APPENDIX G

Porous Asphalt System Design Information

University of New Hampshire Stormwater Center (UNHSC) Gregg Hall ● 35 Colovos Road ● Durham, New Hampshire 03824-3534 ● http://www.unh.edu/erg/cstev

UNHSC Design Specifications for Porous Asphalt Pavement and

Infiltration Beds

Rev. October 2009


UNHSC DESIGN SPECIFICATIONS FOR POROUS ASPHALT PAVEMENT AND INFILTRATION BEDS

TABLE OF CONTENTS

PART 1 GENERAL ........................................................................................................................ 5 1.1 DESCRIPTION ...................................................................................................................... 5 1.2 SUBMITTALS ....................................................................................................................... 5 1.3 QC/QA .................................................................................................................................... 6 1.4 PROJECT CONDITIONS ...................................................................................................... 6 1.5 REFERENCES ....................................................................................................................... 7 PART 2 PRODUCTS ...................................................................................................................... 8 2.1 MATERIALS ......................................................................................................................... 8

A. Porous Media Infiltration Beds ............................................................................................ 8 1. Choker Course ........................................................................................................... 8 2. Filter course material ................................................................................................. 8 3. Filter blanket material ................................................................................................ 9 4. Reservoir Coarse ........................................................................................................ 9 5. Optional Bottom Liner ............................................................................................... 9 6. Non-woven geotextile filter fabric ........................................................................... 11 7. Alternative Applications and Residential Driveways. ............................................. 11

B. Porous Asphalt Mix ........................................................................................................... 12 1. Mix materials ........................................................................................................... 12 2. Polymer Modified PGAB and Mix Designs. ........................................................... 12 3. Anti-Stripping Mix Additives. ................................................................................. 14 4. Coarse Aggregate. .................................................................................................... 15 5. Fine Aggregate. ........................................................................................................ 15 6. Porous Asphalt Mix Design Criteria. ....................................................................... 15

C. Porous Asphalt Mix Production ......................................................................................... 16 1. Mixing Plants. .......................................................................................................... 16 2. Preparation of Asphalt Binder. ................................................................................ 16 3. Preparation of Aggregates. ...................................................................................... 17 4. Mineral filler ............................................................................................................ 17 5. Mixing. ..................................................................................................................... 17 6. QC/QA During Production ...................................................................................... 17 7. Plant Shutdown and Rejection of Mix. .................................................................... 18 8. Striping Paint ........................................................................................................... 19

PART 3 EXECUTION .................................................................................................................. 19 3.1 INSTALLATION ................................................................................................................. 19

A. Porous Media Beds ............................................................................................................ 19 1. Grade Control .......................................................................................................... 19 2. Subgrade Preparation ............................................................................................... 19 3. Porous Media Bed Installation ................................................................................. 20 4. QC/QA requirements for Porous Media Bed Construction. .................................... 21


TABLE OF CONTENTS (CONTINUED) B. Porous Asphalt Pavement Installation ............................................................................... 21

1. Mixing Plant ............................................................................................................ 21 2. Hauling Equipment. ................................................................................................. 21 3. Placing Equipment. .................................................................................................. 22 4. Rollers. ..................................................................................................................... 22 5. Conditioning of Existing Surface. ........................................................................... 23 6. Temperature Requirements. ..................................................................................... 23 7. Spreading and Finishing. ......................................................................................... 23 8. Compaction. ............................................................................................................. 24 9. Joints. ....................................................................................................................... 25 10. Surface Tolerances. .................................................................................................. 26 11. Repair of Damaged Pavement. ................................................................................ 26 12. Striping Paint ........................................................................................................... 26

C. QC/QA for Paving Operations ........................................................................................... 26 PART 4. REFERENCES .............................................................................................................. 27

LIST OF TABLES

Table 1. Submittal requirements. ..................................................................................................... 6 Table 2. Gradations and compaction of choker, filter, and reservoir course materials. ................ 11 Table 3. Non-woven geotextile filter fabric properties. ................................................................ 12 Table 4. Post-Blended SBR Binder QC Plan requirements. .......................................................... 14 Table 5: Porous Asphalt Mix Design Criteria. ............................................................................. 16 Table 6. QC/QA testing requirements during production. ............................................................ 18 Table 7. QC/QA testing tolerances during production. ................................................................. 18 Table 8. QC/QA requirements for porous media bed construction. .............................................. 21 Table 9. QC/QA requirements during paving. ............................................................................... 27

LIST OF FIGURES

Figure 1: Typical Cross-Section for Pervious Pavement System .................................................. 10


UNHSC DESIGN SPECIFICATIONS FOR POROUS ASPHALT PAVEMENT AND INFILTRATION BEDS

NOTICE The specifications listed herein were developed by the UNHSC for UNHSC related projects and represent the author’s best professional judgment. No assurances are given for projects other than the intended application. These design specifications are not a substitute for licensed, qualified engineering oversight and should be reviewed, and adapted as necessary. ACKNOWLEDGEMENTS The original 2007 specifications were completed by collaboration between the University of New Hampshire, of Durham, New Hampshire, and Pike Industries Inc., of Belmont, New Hampshire. The principal UNH authors were Joshua F. Briggs, Robert M. Roseen, PE, PhD, and Thomas P. Ballestero, PE, PhD, PH, CGWP, PG. The principal author from Pike Industries was the Corporate Quality Control Manager, Jeff Pochily. Other contributions to the project were made by Grant Swenson, also of Pike Industries. The revised specifications (2009) were prepared by the UNHSC after a round table discussion with New Hampshire Asphalt Manufacturers (Rick Charbonneau, Mark Charbonneau, and Keith Dane of Continental Paving, Jeff Lewis of Brox Industries, and Mary Wescott, Dave Duncan, and Jeff Pochily of Pike Industries) and a round table discussion with design engineers. The 2009 specifications were also reviewed and revised by Antonio P. Ballestero, Jr., PE. The UNH Stormwater Center is housed within the Environmental Research Group (ERG) at the University of New Hampshire (UNH) in Durham, New Hampshire. Funding for the program was and continues to be provided by the Cooperative Institute for Coastal and Estuarine Environmental Technology (CICEET) and the National Oceanic and Atmospheric Administration (NOAA).

Porous Asphalt Pavement and Infiltration Beds Design Specifications Page-5

University of New Hampshire Stormwater Center –October 2009

PART 1 GENERAL

1.1 DESCRIPTION A. This specification is intended to be used for porous asphalt pavement in parking lot applications.

Stormwater management functions of porous asphalt installations include water quality treatment, peak flow reduction, storm volume reduction via groundwater recharge, and increased hydrograph time lag. This specification is intended for a cold climate application based upon the field experience at the UNHSC porous asphalt parking lot located in Durham, New Hampshire, however the specification can be adapted to projects elsewhere provided that selection of materials and system design reflects local conditions, constraints, and objectives.

B. The work of this Section includes subgrade preparation, installation of the underlying porous media beds, and porous asphalt mix (mix) design, production, and installation. Porous media beds refer to the material layers underlying the porous asphalt pavement. Porous asphalt pavement refers to the compacted mix of modified asphalt, aggregate, and additives.

C. The porous asphalt pavement specified herein is modified after the National Asphalt Pavement Association (NAPA) specification outlined in Design, Construction, and Maintenance Guide for Porous Asphalt Pavements, Information Series 131 (2003) and Design, Construction, and Maintenance of Open-Graded Friction Courses, Information Series 115 (2002).

D. Alternative specifications for mix, such as Open Graded Friction Courses (OGFC) from Federal Agencies or state Departments of Transportation (DOT), may be used if approved by the Engineer. The primary requirements for the specifications of the mix are performance grade (PG) asphalt binder, binder content, binder draindown, aggregate gradation, air void content, retained tensile strength (TSR).

1.2 SUBMITTALS

A. Submit a list of materials proposed for work under this Section including the name and address of the materials producers and the locations from which the materials are to be obtained.

B. Submit certificates, signed by the materials producers and the relevant subcontractors, stating that materials meet or exceed the specified requirements, for review and approval by the Engineer.

C. Submit samples of materials for review and approval by the Engineer. For mix materials, samples may be submitted only to the QA inspector with the Engineer’s approval.

D. Submittal requirements for samples and certificates are summarized in 1.3 QC/QA

A. Use adequate numbers of skilled workers who are thoroughly trained and experienced in the necessary crafts and who are completely familiar with the specified requirements and the methods needed for proper performance of the work in this section.

B. Codes and Standards - All materials, methods of construction and workmanship shall conform to applicable requirements of AASHTO ASTM Standards, NHDOT Standard Specifications for



Road and Bridge Construction, latest revised (including supplements and updates), or other standards as specified.

C. QC/QA requirements for production of mix are discussed in the Materials section, and for construction of the porous media beds and paving in the Execution section.

E. Table 1 and discussed in further detail in the Materials section.

1.3 QC/QA

D. Use adequate numbers of skilled workers who are thoroughly trained and experienced in the necessary crafts and who are completely familiar with the specified requirements and the methods needed for proper performance of the work in this section.

E. Codes and Standards - All materials, methods of construction and workmanship shall conform to applicable requirements of AASHTO ASTM Standards, NHDOT Standard Specifications for Road and Bridge Construction, latest revised (including supplements and updates), or other standards as specified.

F. QC/QA requirements for production of mix are discussed in the Materials section, and for construction of the porous media beds and paving in the Execution section.

Table 1. Submittal requirements.

Material or Pavement Course* Properties to be reported on Certificate**

choker course, reservoir course gradation, max. wash loss, min. durability index, max. abrasion loss, air voids (reservoir course)

filter course gradation, permeability/ sat. hydraulic conductivity filter blanket gradation geotextile filter fabric manufacturer's certification, AOS/EOS, tensile strength striping paint certificate binder PGAB certification coarse aggregate gradation, wear, fracture faces (fractured and elongated) fine aggregate gradation, silicone manufacturer's certification Fibers (optional) manufacturer's certification mineral filler (optional) manufacturer's certification fatty amines (optional anti-strip) manufacturer's certification hydrated lime (optional anti-strip) manufacturer's certification

* Samples of each material shall be submitted to the Engineer (or QA inspector for mix). These samples must be in sufficient volume to perform the standardized tests for each material.

** At a minimum, more material properties may be required (refer to Materials Section).

1.4 PROJECT CONDITIONS A. Site Assessment should be performed per the steps outlined in IS 131 (NAPA, 2003).



B. Construction Phasing should be performed as outlined in IS 131 (NAPA, 2003).

C. Protection of Existing Improvements 1. Protect adjacent work from the unintended dispersal/splashing of pavement materials.

Remove all stains from exposed surfaces of pavement, structures, and grounds. Remove all waste and spillage. If necessary, limit access to adjacent work/structures with appropriate signage and/or barriers.

2. Proper erosion and sediment control practices shall be provided in accordance with existing regulations. Do not damage or disturb existing improvements or vegetation. Provide suitable protection where required before starting work and maintain protection throughout the course of the work. This includes the regular, appropriate inspection and maintenance of the erosion and sediment control measures.

3. Restore damaged areas, including existing pavement on or adjacent to the site that has been damaged as a result of construction work, to their original condition or repair as directed to the satisfaction of the Engineer at no additional cost.

D. Safety and Traffic Control 1. Notify and cooperate with local authorities and other organizations having jurisdiction

when construction work will interfere with existing roads and traffic. 2. Provide temporary barriers, signs, warning lights, flaggers, and other protections as

required to assure the safety of persons and vehicles around and within the construction area and to organize the smooth flow of traffic.

E. Weather Limitations 1. Porous asphalt, Open graded friction course, or dense-mixed asphalt shall not be placed

between November 15 and March 15, or when the ambient air temperature at the pavement site in the shade away from artificial heat is below 16 °C (60 °F) or when the actual ground temperature is below 10 °C (50 °F). Only the Engineer may adjust the air temperature requirement or extend the dates of the pavement season.

2. The Contractor shall not pave on days when rain is forecast for the day, unless a change in the weather results in favorable conditions as determined by the Engineer.

1.5 REFERENCES

A. General Porous Asphalt Bituminous Paving and Groundwater Infiltration Beds, specification by UNH Stormwater Center, February, 2005.

B. Design, Construction, and Maintenance Guide for Porous Asphalt Pavements, Information Series 131, National Asphalt Pavement Association (NAPA), 2003.

C. Design, Construction, and Maintenance of Open-Graded Friction Courses, Information Series 115, NAPA, 2002.

D. Annual Book of ASTM Standards, American Society for Testing and Materials, Philadelphia, PA, 1997 or latest edition.

E. Standards of the American Association of State Highway and Transportation Officials (AASHTO), 1998 or latest edition.

F. Section 401- Plant Mix Pavements – General, in Standard Specifications for Road and Bridge Construction – State of New Hampshire Department of Transportation, 2006.

G. Section 02725 - General Porous Pavement and Groundwater Infiltration Beds, specification from NAPA Porous Asphalt Seminar handout, Cahill Associates, Inc., 2004.

H. Correlations of Permeability and Grain Size, Russell G. Shepherd, Groundwater 27 (5), 1989.



I. Groundwater, R. Allan Freeze and John A. Cherry, 1979.

PART 2 PRODUCTS

2.1 MATERIALS

A. Porous Media Infiltration Beds Below the porous asphalt itself are located the porous media infiltration beds (Figure 1), from top to bottom: a 4” – 8 “(10 - 20 cm) (minimum) thick layer of choker course of crushed stone (8” is preferable to alleviate compaction issues with the porous asphalt); an 8” to 12” (20 cm to 30 cm) minimum thickness layer of filter course of poorly graded sand (a.k.a. bankrun gravel or modified 304.1); 3” (8 cm) minimum thickness filter blanket that is an intermediate setting bed (pea gravel); and a reservoir course of crushed stone, thickness dependant on required storage and underlying native materials. Alternatively, the pea gravel layer could be thickened and used as the reservoir course depending upon subsoil suitability. This alternative simplifies subbase construction. For lower permeability native soils, perforated or slotted drain pipe is located in the stone reservoir course for drainage. This drain pipe can be daylighted to receiving waters or connected into other stormwater management infrastructure (wetland, storm sewer, etc.). The fine gradation of the filter course is for enhanced filtration and delayed infiltration. The high air void content of the uniformly graded crushed stone reservoir course: maximizes storage of infiltrated water thereby allowing more time for water to infiltrate between storms; and creates a capillary barrier that arrests vertical water movement and in doing so prevents winter freeze-thaw and heaving. The filter blanket is placed to prevent downward migration of filter course material into the reservoir course. The optional underdrain in the reservoir course is for hydraulic relief (typically raised off of the bottom of the reservoir stone layer for enhanced groundwater recharge). Nonwoven geotextile filter fabric (geotextile) is used only for stabilizing the sloping sides of the porous asphalt system excavation and not to be used on the bottom of the system unless needed for structural reasons.

1. Choker Course

Material for the choker course and reservoir course shall meet the following: Maximum Wash Loss of 0.5% Minimum Durability Index of 35 Maximum Abrasion Loss of 10% for 100 revolutions, and maximum of 50% for 500

revolutions. Material for the choker course and reservoir course shall have the AASHTO No. 57 and AASHTO No. 3 gradations, respectively, as specified in



Table 2. If the AASHTO No. 3 gradation cannot be met, AASHTO No. 5 is acceptable with approval of the Engineer. AASHTO no. 3 is also suitable for the choker course.

2. Filter course material

Filter course material shall have a hydraulic conductivity (also referred to as coefficient of permeability) of 10 to 60 ft/day at 95% standard proctor compaction unless otherwise approved by the Engineer. Great care needs to be used to not over compact materials. Over-compaction results with loss of infiltration capacity. The filter course material is commonly referred to as a bankrun gravel (modified NHDOT 304.1). In order to select an appropriate gradation, coefficient of permeability may be estimated through an equation that relates gradation to permeability, such as described in Correlations of Permeability and Grain Size (Shepherd, 1989) or in Section 8.7 Estimation of Saturated Hydraulic Conductivity (Freeze and Cherry, 1979). The hydraulic conductivity should be determined by ASTM D2434 and reported to the Engineer.

3. Filter blanket material

Filter blanket material between the filter course and the reservoir course shall be an intermediate size between the finer filter course above, and the coarser reservoir course below, for the purpose of preventing the migration of a fine setting bed into the coarser reservoir material. An acceptable gradation shall be calculated based on selected gradations of the filter course and reservoir course using criteria outlined in the HEC 11 (Brown and Clyde, 1989). A pea-gravel with a median particle diameter of 3/8” (9.5 mm) is commonplace.

4. Reservoir Coarse Reservoir Coarse thickness is dependent upon the following criteria (that vary from site to site): a. A 4” (10 cm) minimum thickness of reservoir course acts as a capillary barrier for frost

heave protection. The reservoir course is located at the interface between subbase and native materials.

b. 4-in. (10 cm) minimum thickness if the underlying native materials are either well drained

(Hydrologic Group A soils).

c. 8-in. (30 cm) minimum thickness if subdrains are installed. Subdrains insure that the subbase is well drained

d. Subdrains, if included, are elevated a minimum of 4” (10 cm) from the reservoir course

bottom to provide storage and infiltration for the water quality volume. If the system is lined ,

e. Subbase thickness is determined from subbase materials having sufficient void space to

store the design storm,

Example: If the 25-year storm is 5.1” (13 cm) of rainfall depth, and the reservoir void space is 30%, then the minimum subbase thickness = 5.1”/0.3 = 17” (43.2 cm).



f. Pavement system and subbase thickness are > 0.65 * design frost depth for area.

Example: Durham, New Hampshire, 48” (122 cm) = Dmaximum frost, therefore the minimum depth to the bottom of the subbase = 0.65(48”) = 32” (81 cm).

5. Optional Bottom Liner Bottom Liner is only recommended for aquifer protection or infiltration prevention. This liner is to be located at the interface between subbase and native materials and is dependent upon the following:

a. As with any infiltration system, care must be taken when siting porous asphalt systems

close to locations where hazardous materials are handled/trafficked, or where high contaminant loading may threaten groundwater, or where infiltration is undesirable (nearby foundations, slope stability, etc.). In such cases, the systems can be lined to prevent infiltration yet still preserving water quality, hydrograph lag, and peak flow reduction benefits.

b. Refer to state or USEPA guidelines regarding the use of infiltration systems (USEPA,

1999, CalTrans, 2003, WI DNR, 2004, USEPA, 2004)

c. Suitable liners may include Hydrologic Group D soils, HDPE liners, or suitable equivalent. Refer to state or USEPA guidelines regarding selection of impermeable liners (USEPA, 2004).

d. Filter fabrics or geotextile liners are not recommended for use on the bottom of the porous

asphalt system (at the base of the stone reservoir subbase) if designing for infiltration. Filter fabric usage in stormwater filtration has been known to clog prematurely. Graded stone filter blankets are recommended instead.

e. Geotextile filter fabrics may be used if designing on poor structural, and low conductivity

soils. Fabric usage would be limited to the bottom and sides of the excavation. No fabric is to be used within the subbase, only on the perimeter.

Figure 1: Typical Parking Area Cross-Section for Pervious Pavement System



`

Choker Course: 4”-8” (10 – 20 cm) minimum

Pervious pavement: 4-6” (10 - 15 cm) of porous asphalt

Filter Course: 8” - 12” (20 - 30 cm) minimum thickness of subbase (aka. bank run gravel or modified 304.1)

Native materials

Filter Blanket: intermediate setting bed: 3” (8 cm) thickness of 3/8” (1 cm) pea gravel

Reservoir Course: 4” (10 cm) minimum thickness of 3/4” (2 cm) crushed stone for frost protection, 4-6” (10-15 cm) diameter perforated subdrains with 2” cover

Optional-Liner for land uses where infiltration is undesirable (e.g., hazardous materials handling, sole-source aquifer protection)



Table 2. Gradations and compaction of choker, filter, and reservoir course materials.

US Standard Sieve Size

Inches/mm

Percent Passing (%)

Choker Course (AASHTO No.

57)

Filter Course (Modified

NHDOT 304.1)

Reservoir Course

(AASHTO No. 3)

Reservoir Course Alternative*

(AASHTO No. 5)

6/150 - 100 - 2½/63 - 100 - 2 /50 - 90 – 100 -

1½/37.5 100 35 – 70 100 1/25 95 - 100 0 – 15 90 – 100 ¾/19 - - 20 - 55

½/12.5 25 - 60 0 - 5 0 - 10 3/8/9.5 - - 0 - 5 #4/4.75 0 - 10 70-100 - #8/2.36 0 - 5 -

#200/0.075 0 – 6** % Compaction

ASTM D698 / AASHTO T99

95 95 95 95

* Alternate gradations (e.g. AASHTO No. 5) may be accepted upon Engineer’s approval. ** Preferably less than 4% fines

6. Non-woven geotextile filter fabric Filter fabric is only recommended for the sloping sides of the porous asphalt system excavation. It shall be Mirafi 160N, or approved equal and shall conform to the specifications in



Table 3. Mirafi ® 160N is a non-woven geotextile composed of polypropylene fibers, which are formed into a stable network such that the fibers retain their relative position. 160N is inert to biological degradation and resists naturally encountered chemicals, alkalis, and acids. 7. Alternative Applications and Residential Driveways. The recommendations above are based on a commercial parking application for both traffic and contaminant load. Alternative applications such as residential driveways and low use applications may justify the use of alternative subbase thicknesses for the porous media beds, filter blanket, and geotextiles. Residential driveway applications have been designed with a subbase limited to only an 8” compacted choker course. Variations should consider structural load requirements for material thickness, and contaminant load for filter course thickness. A reduced total system thickness (Section 2.1.3.f) will subject the pavement to greater freeze thaw susceptibility.



Table 3. Non-woven geotextile filter fabric properties.

Mechanical Properties Test Method Unit Minimum Average Roll Values MD* CD**

Grab Tensile Strength ASTM D 4632 kN (lbs) 0.71 (160) 0.71 (160) Grab Tensile Elongation ASTM D 4632 % 50 50 Trapezoid Shear Strength ASTM D 4533 kN (lbs) 0.27 (60) 0.27 (60)

Mullen Burst Strength ASTM D 3786 kPa (psi) 2100 (305) 2100 (305) Puncture Strength ASTM D 4833 kN (lbs) 0.42 (95) 0.42 (95)

Apparent Opening Size (AOS) ASTM D 4751 mm (US Sieve) 0.212 (70) 0.212 (70)

Permittivity ASTM D 4491 sec-1 1.4 1.4 Permeability ASTM D 4491 cm/sec 0.22 0.22 Flow Rate ASTM D 4491 lpm/m2 (gpm/ft2) 4,477 (110) 4,477 (110)

UV Resistance (at 500 hours) ASTM D 4355 % strength retained 70 70

Physical

Properties Test Method Unit Typical Value

Weight ASTM D 5261 g/m2 (oz/yd2) 217 (6.4) Thickness ASTM D 5199 mm (mils) 1.9 (75)

Roll dimension (width x length) m (ft) 4.5 x 91 (15 x 300)

Roll area m2 (yd2) 410 (500) Estimated roll

weight kg (lb) 99 (217)

*MD - Machine Direction; **CD - Cross-machine Direction

B. Porous Asphalt Mix 1. Mix materials Mix materials consist of modified performance grade asphalt binder (PGAB), coarse and fine aggregates, and optional additives such as silicone, fibers, mineral fillers, fatty amines, and hydrated lime. Materials shall meet the requirements of the NAPA’s Design, Construction, and Maintenance of Open-Graded Friction Courses, Information Series 115 (2002), except where noted otherwise below or approved in writing by the Engineer.

2. Polymer Modified PGAB and Mix Designs. The asphalt binder shall be a polymer and/or fiber modified Performance Graded asphalt binder (PGAB) used in the production of Superpave Hot Mix Asphalt (HMA) mixtures. Ideally for maximum durability, the PGAB shall be two grades stiffer than that required for dense mix asphalt (DMA) parking lot installations, which is often achieved by adding a polymer and/or fiber. Mix designs will meet or exceed criteria listed in Table 5 The PGAB polymer modifiers are to be either styrene butadiene rubber (SBR) or styrene butadiene styrene (SBS). SBS is typically reserved for large projects as terminal pre-blending is required. SBR is feasible for smaller projects as it can be blended at the plant or terminal blended. The quantity of rubber solids in the SBR shall typically be 1.5-3% by weight of the bitumen



content of the mix. The dosage of fiber additives shall be either 0.3 percent cellulose fibers or 0.4 percent mineral fibers by total mixture mass. Fibers are a simple addition either manually for a batch plant or automated for larger drum plants. The binder shall meet the requirements of AASHTO M320. The PGAB may be pre-blended or post-blended. The pre-blended binder can be pre-blended at the source or at a terminal. For post-blended addition, the modifier can either be in-line blended or injected into the pugmill at the plant. The following asphalt mix designs are recommended: a. PG 64-28 with 5 pounds of fibers per ton of asphalt mix. This mix is recommended for smaller

projects with lower traffic counts or loading potential. This mix is manageable at common batch plants.

b. Pre-Blended PG 64-28 SBS with 5 pounds of fibers per ton of asphalt mix. This mix is recommended for large projects > 1acre where high durability pavements are needed. The SBS will be supplied by an approved PGAB supplier holding a Quality Control Plan approved by the state DOT. A Bill of Lading (BOL) will be delivered with each transport of PG 64-28 SBS. A copy of the BOL will be furnished to the QA inspector at the Plant.

c. Post-Blended PG 64-28 SBR with 5 pounds of fibers per ton of asphalt mix. This mix is

recommended for projects where high durability pavements are needed. The SBR will be supplied by a HMA plant approved to perform in-line blending or blending by injection into the pugmill. A Post-Blended SBR Binder Quality Control Plan (Table 4) will be submitted to the Engineer for approval at least 10 working days prior to production.

d. Pre-Blended PG 76-22 modified with SBS and 5 pounds of fibers per ton of asphalt mix. This

mix is recommended for large sites anticipating high wheel load (H-20) and traffic counts for maximum durability. The SBS will be supplied by an approved PGAB supplier holding a Quality Control Plan approved by the state DOT. A Bill of Lading (BOL) will be delivered with each transport of PG 76-22 SBS. A copy of the BOL will be furnished to the QA inspector at the Plant.

e. Post-Blended PG 76-22 modified with SBR and 5 pounds of fibers per ton of asphalt mix. This

mix is recommended for large sites anticipating high wheel load (H-20) and traffic counts for maximum durability. The SBR will be supplied by a HMA plant approved to perform in-line blending or blending by injection into the pugmill. A Post-Blended SBR Binder Quality Control Plan (Table 4) will be submitted to the Engineer for approval at least 10 working days prior to production.

f. Quality control plans may be altered at the discretion of the Engineer and based on feasible

testing as suggested by the asphalt producer. Certain QC testing requirements during production may not be feasible for small projects in which limited asphalt is generated. Some testing methods cannot be completed during the time needed during small batch (less than approximately 50 tons of porous asphalt mix) production. The feasibility should be assessed with the Engineer and producer.



Table 4. Post-Blended SBR Binder QC Plan requirements.

3. Anti-Stripping Mix Additives. The mix shall be tested for moisture susceptibility and asphalt stripping from the aggregate by AASHTO T283. If the retained tensile strength (TSR) < 80% upon testing, a heat stable

The QC Plan will contain: 1. Company name and address2. Plant location and address3. Type of Facility4. Contact information for the Quality Control Plan Administrator5. QC Tests to be performed on each PGAB6. Name(s) of QC Testing Lab to perform QC and Process Control testing.7. Actions to be taken for PG Binders and SBR in Non compliance8. List of mechanical controls (requirements below)9. List of process controls and documentation (requirements below)

List of Mechanical Controls1. Liquid SBR no-flow alert system with an “alert” located in the control room and automatic documentation of a no flow situation on the printout2. Provide means of calibrating the liquid SBR metering system to a delivery tolerance of 1%.3. A batching tolerance at the end of each day’s production must be within 0.5% of the amount of SBR solids specified.4. Mag-flow meter (other metering system may be considered)5. Method of sampling liquid SBR

List of Process Controls and Documentation1. Printouts of liquid SBR and PG binder quantities must be synchronized within one minute of each other2. SBR supplier certification showing the percent of SBR solids in liquid SBR3. Test results of a lab sample blended with the specified dosage of SBR. At a minimum, provide the name of the PGAB and liquid SBR suppliers, and PGAB information such as grade and lot number, and SBR product name used for the sample.4. MSDS sheet for liquid SBR5. Handling, storage, and usage requirements will be followed as required by the liquid SBR manufacturer6. At a minimum, provide a table showing proposed rate of SBR liquid (L/min.) in relation to HMA production rate (tons per hour, TPH) for the % solids in liquid SBR, quantity of SBR specified for HMA production, and the specific gravity of the SBR.

7. QCT or QC Plan Administrator must be responsible for documenting quantities, ensuring actual use is within tolerance, etc. All printouts, calculations, supplier certifications etc. must be filed and retained as part of the QCTs daily diary/reports.

8. Method and Frequency of testing at the HMA plant, including initial testing and specification testing.*This Plan shall be submitted to the Engineer 10 days before production.



additive shall be furnished to improve the anti-stripping properties of the asphalt binder. Test with one freeze-thaw cycle (rather than five recommended in NAPA IS 115). The amount and type of additive (e.g. fatty amines or hydrated lime) to be used shall be based on the manufacturer’s recommendations, the mix design test results, and shall be approved by the Engineer. Silicone shall be added to the binder at the rate of 1.5 mL/m3 (1 oz. per 5000 gal). Fibers may be added per manufacturer and NAPA IS 115 recommendation if the draindown requirement cannot be met (<0.3% via ASTM D6390) provided that the air void content requirement is met (>18%, or >16% as tested with CoreLok device). Additives should be added per the relevant DOT specification and NAPA IS 115.

4. Coarse Aggregate. Coarse aggregate shall be that part of the aggregate retained on the No. 8 sieve; it shall consist of clean, tough, durable fragments of crushed stone, or crushed gravel of uniform quality throughout. Coarse aggregate shall be crushed stone or crushed gravel and shall have a percentage of wear as determined by AASHTO T96 of not more than 40 percent. In the mixture, at least 75 percent, by mass (weight), of the material coarser than the 4.75 mm (No. 4) sieve shall have at least two fractured faces, and 90 percent shall have one or more fractured faces (ASTM D5821). Coarse aggregate shall be free from clay balls, organic matter, deleterious substances, and a not more than 8.0% of flat or elongated pieces (>3:1) as specified in ASTM D4791.

5. Fine Aggregate.

The fine aggregate shall be that part of the aggregate mixture passing the No. 8 sieve and shall consist of sand, screenings, or combination thereof with uniform quality throughout. Fine aggregate shall consist of durable particles, free from injurious foreign matter. Screenings shall be of the same or similar materials as specified for coarse aggregate. The plasticity index of that part of the fine aggregate passing the No. 40 sieve shall be not more than 6 when tested in accordance with AASHTO T90. Fine aggregate from the total mixture shall meet plasticity requirements.

6. Porous Asphalt Mix Design Criteria. The Contractor shall submit a mix design at least 10 working days prior to the beginning of production. The Contractor shall make available samples of coarse aggregate, fine aggregate, mineral filler, fibers and a sample of the PGAB that will be used in the design of the mixture. A certificate of analysis (COA) of the PGAB will be submitted with the mix design. The COA will be certified by a laboratory meeting the requirements of AASHTO R18. The Laboratory will be certified by the state DOT, regional equivalent (e.g. NETTCP), and/or qualified under ASTM D3666. Technicians will be certified by the regional certification agency (e.g. NETTCP) in the discipline of HMA Plant Technician. Bulk specific gravity (SG) used in air void content calculations shall not be determined and results will not be accepted using AASHTO T166 (saturated surface dry), since it is not intended for open graded specimens (>10% AV). Bulk SG shall be calculated using AASHTO T275 (paraffin wax) or ASTM D6752 (automatic vacuum sealing, e.g. CoreLok). Air void content shall be calculated from the bulk SG and maximum theoretical SG (AASHTO T209) using ASTM D3203.



The materials shall be combined and graded to meet the composition limits by mass (weight) as shown in Table 5.

Table 5: Porous Asphalt Mix Design Criteria.

Sieve Size (inch/mm) Percent Passing (%) 0.75/19 100

0.50/12.5 85-100 0.375/9.5 55-75 No.4/4.75 10-25 No.8/2.36 5-10

No.200/0.075 (#200) 2-4 Binder Content (AASHTO T164) 6 - 6.5%

Fiber Content by Total Mixture Mass 0.3% cellulose or 0.4% mineral

Rubber Solids (SBR) Content by Weight of the Bitumen

1.5-3% or TBD

Air Void Content (ASTM D6752/AASHTO T275)

16.0-22.0%

Draindown (ASTM D6390)* < 0.3 % Retained Tensile Strength (AASHTO 283)** > 80 %

Cantabro abrasion test on unaged samples (ASTM D7064-04)

< 20%

Cantabro abrasion test on 7 day aged samples < 30% *Cellulose or mineral fibers may be used to reduce draindown.

**If the TSR (retained tensile strength) values fall below 80% when tested per NAPA IS 131 (with a single freeze thaw cycle rather than 5), then in Step 4, the contractor shall employ an antistrip additive, such as hydrated lime (ASTM C977) or a fatty amine, to raise the TSR value above 80%.

C. Porous Asphalt Mix Production 1. Mixing Plants.

Mixing plants shall meet the requirements of hot mix asphalt plants as specified in the state DOT or regional equivalent unless otherwise approved by the Engineer (e.g. Section 401- Plant Mix Pavements – General for Quality Assurance specifications in the Standard Specifications for Road and Bridge Construction – State of New Hampshire DOT, 2006, or latest revised edition and including supplemental specifications and updates).

2. Preparation of Asphalt Binder. The asphalt material shall be heated to the temperature specified in the state DOT specification (if using a DOT spec for the mix) in a manner that will avoid local overheating. A continuous supply of asphalt material shall be furnished to the mixer at a uniform temperature.



3. Preparation of Aggregates.

The aggregate for the mixture shall be dried and heated at the mixing plant before being placed in the mixer. Flames used for drying and heating shall be properly adjusted to avoid damaging the aggregate and depositing soot or unburned fuel on the aggregate.

4. Mineral filler Mineral filler if required to meet the grading requirements, shall be added in a manner approved by the Engineer after the aggregates have passed through the dryer.

5. Mixing. The above preparation of aggregates does not apply for drum-mix plants. The dried aggregate shall be combined in the mixer in the amount of each fraction of aggregate required to meet the job-mix formula and thoroughly mixed prior to adding the asphalt material. The dried aggregates shall be combined with the asphalt material in such a manner as to produce a mixture that when discharged from the pugmill is at a target temperature in the range that corresponds to an asphalt binder viscosity of 700 to 900 centistokes and within a tolerance of ± 11 °C (± 20 °F). The asphalt material shall be measured or gauged and introduced into the mixer in the quantity determined by the Engineer for the particular material being used and at the temperature specified in the relevant specification. After the required quantity of aggregate and asphalt material has been introduced into the mixer, the materials shall be mixed until a complete and uniform coating of the particles and a thorough distribution of the asphalt material throughout the aggregate is secured. The mixing time will be regulated by the Engineer. All plants shall have a positive means of eliminating oversized and foreign material from being incorporated into the mixer.

6. QC/QA During Production The Contractor shall provide at Contractors’ expense and the Engineer’s approval a third-party QA Inspector to oversee and document mix production. All mix testing results during production should be submitted to the QA Inspector. The QC plan may be altered at the discretion of the Engineer and based on feasible testing as suggested by the asphalt producer. Certain QC testing requirements during production may not be feasible for small projects in which limited asphalt is generated. Some testing methods cannot be completed during the time needed during small batch production. The feasibility should be assessed with the Engineer and producer. The mixing plant shall employ a Quality Control Technician (QCT). The QCT will perform QC/QA testing and will be certified in the discipline of HMA Plant Technician by the relevant certifying agency (e.g. NETTCP in New England). The Contractor shall sample, test and evaluate the mix in accordance with the methods and minimum frequencies in Table 6 and the



Post-Blended SBR Binder Quality Control Plan (if applicable).

Table 6. QC/QA testing requirements during production.

If an analyzed sample is outside the testing tolerances immediate corrective action will be taken. After the corrective action has been taken the resulting mix will be sampled and tested. If the re-sampled mix test values are outside the tolerances the Engineer will be immediately informed. The Engineer may determine that it is in the best interest of project that production is ceased. The Contractor will be responsible for all mix produced for the project. Testing Tolerances During Production. Testing of the air void content, binder draindown, and TSR shall be within the limits set in Table 6. The paving mixture produced should not vary from the design criteria for aggregate gradation and binder content by more than the tolerances in Table 7.

Table 7. QC/QA testing tolerances during production.

Should the paving mixture produced vary from the designated grading and asphalt content by more than the above tolerances, the appropriate production modifications are to be made until the porous asphalt mix is within these tolerances. Samples of the mixture, when tested in accordance with AASHTO T164 and T30, shall not vary from the grading proportions of the aggregate and binder content designated by the Engineer by more than the respective tolerances specified above and shall be within the limits specified for the design gradation.

7. Plant Shutdown and Rejection of Mix.

Should the porous asphalt mix not meet the tolerances specified in this section upon repeat testing, the Engineer may reject further loads of mix. Mix that is loaded into trucks during the

Test Min. Frequency Test MethodTemperature in Truck at Plant 6 times per day

Gradation greater of either (a) 1 per 500 tons, (b) 2 per day, or (c) 3 per job

AASHTO T30

Binder Content greater of either (a) 1 per 500 tons, (b) 2 per day, or (c) 3 per job

AASHTO T164

Air Void Content greater of either (a) 1 per 500 tons, (b) 2 per day, or (c) 3 per job

ASTM D6752

Binder Draindown greater of either (a) 1 per 500 tons, (b) 1 per day, or (c) 1 per job

ASTM D6390

Sieve Size (inch/mm) Percent Passing0.75/19 -0.50/12.5 ±6.00.375/9.5 ±6.0No.4/4.75 ±5.0No.8/2.36 ±4.0No.200/0.075 (#200) ±2.0%PGAB +0.4, -0.2



time that the plant is changing operations to comply with a failed test shall not be accepted, and should be recycled at the plant.

8. Striping Paint

Striping paint shall be latex, water-base emulsion, ready-mixed, and complying with pavement marking specifications PS TT-P-1952.

PART 3 EXECUTION

3.1 INSTALLATION

A. Porous Media Beds Protection of native materials from over compaction is important. Proper compaction of select subbase materials is essential. Improper compaction of subbase materials will result in either 1) low pavement durability from insufficient compaction, or 2) poor infiltration due to over-compaction of subbase. Care must be taken to assure proper compaction as detailed below.

1. Grade Control

a. Establish and maintain required lines and elevations. The Engineer shall be notified for review and approval of final stake lines for the work before construction work is to begin. Finished surfaces shall be true to grade and even, free of roller marks and free of puddle-forming low spots. All areas must drain freely. Excavation elevations should be within +/- 0.1 ft (+/- 3 cm).

b. If, in the opinion of the Engineer, based upon reports of the testing service and inspection,

the quality of the work is below the standards which have been specified, additional work and testing will be required until satisfactory results are obtained.

c. The Engineer shall be notified at least 24 hours prior to all porous media bed and porous

pavement work.

2. Subgrade Preparation

a. Native subgrade refers to materials beyond the limit of the excavation. The existing native subgrade material under all bed areas shall NOT be compacted or subject to excessive construction equipment traffic prior to geotextile and stone bed placement. Compaction is acceptable if an impermeable liner is used at the base of the porous asphalt system and infiltration is not desired.

b. Where erosion of the native material subgrade has caused accumulation of fine materials

and/or surface ponding, this material shall be removed with light equipment and the underlying soils scarified to a minimum depth of 6 inches with a York rake or equivalent and light tractor.

c. Bring subgrade to line, grade, and elevations indicated. Fill and lightly regrade any areas



damaged by erosion, ponding, or traffic compaction before the placing of the stone subbase.

d. All bed bottoms are as level as feasible to promote uniform infiltration. For pavements subbases constructed on grade, soil or fabric barriers should be constructed along equal elevation for every 6-12” of grade change to act as internal check dams. This will prevent erosion within the subbase on slope.

3. Porous Media Bed Installation

a. Subbase refers to materials below pavement surface and above native subgrade. Upon

completion of subgrade work, the Engineer shall be notified and shall inspect at his/her discretion before proceeding with the porous media bed installation.

b. Sideslope geotextile and porous media bed aggregate shall be placed immediately after

approval of subgrade preparation. Any accumulation of debris or sediment which has taken place after approval of subgrade shall be removed prior to installation of geotextile at no extra cost to the Owner.

c. Place sideslope geotextile in accordance with manufacturer's standards and

recommendations. Adjacent strips of geotextile shall overlap a minimum of sixteen inches (16"). Secure geotextile at least four feet (1.2 m) outside of the bed excavation and take any steps necessary to prevent any runoff or sediment from entering the storage bed.

d. Install filter course aggregate in 8-inch maximum lifts to a MAXIMUM of 95% standard

proctor compaction (ASTM D698 / AASHTO T99). Install aggregate to grades indicated on the drawings.

e. Install choker, gravel, and stone base course aggregate to a MAXIMUM of 95%

compaction standard proctor (ASTM D698 / AASHTO T99). Choker should be placed evenly over surface of filter course bed, sufficient to allow placement of pavement, and notify Engineer for approval. Choker base course thickness shall be sufficient to allow for even placement of the porous asphalt but no less than 4-inches (10 cm) in depth.

f. The density of subbase courses shall be determined by AASHTO T 191 (Sand-Cone

Method), AASHTO T 204 (Drive Cylinder Method), or AASHTO T 238 (Nuclear Methods), or other approved methods at the discretion of the supervising engineer.

g. The infiltration rate of the compacted subbase shall be determined by ASTM D3385 or

approved alternate at the discretion of the supervising engineer. The infiltration rate shall be no less 5-30 ft/day or 50% of the hydraulic conductivity (D2434) at 95% standard proctor compaction (refer to section 2.1.A.5).

h. Compaction of subbase course material shall be done with a method and adequate water to

meet the requirements. Rolling and shaping shall continue until the required density is attained. Water shall be uniformly applied over the subbase course materials during compaction in the amount necessary for proper consolidation.



i. Rolling and shaping patterns shall begin on the lower side and progress to the higher side of the subbase course while lapping the roller passes parallel to the centerline. Rolling and shaping shall continue until each layer conforms to the required grade and cross-section and the surface is smooth and uniform.

j. Following placement of subbase aggregate, the sideslope geotextile shall be folded back

along all bed edges to protect from sediment washout along bed edges. At least a four-foot edge strip shall be used to protect beds from adjacent bare soil. This edge strip shall remain in place until all bare soils contiguous to beds are stabilized and vegetated. In addition, take any other necessary steps to prevent sediment from washing into beds during site development. When the site is fully stabilized, temporary sediment control devices shall be removed.

4. QC/QA requirements for Porous Media Bed Construction.

QC/QA activities are summarized in Table 8.

B. Porous Asphalt Pavement Installation

1. Mixing Plant The mixing plant, hauling and placing equipment, and construction methods shall be in conformance with NAPA IS 131 and applicable sections of the state DOT’s specification for asphalt mixes. The use of surge bins shall not be permitted.

Table 8. QC/QA requirements for porous media bed construction.

2. Hauling Equipment. The open graded mix shall be transported in clean vehicles with tight, smooth dump beds that have been sprayed with a non-petroleum release agent or soap solution to prevent the mixture from adhering to the dump bodies. Mineral filler, fine aggregate, slag dust, etc.

Activity ScheduleContractor to notify Engineer for approval 24 hours in advance of start of work

Contractor to employ soil inspector acceptable to Engineer NA

Contractor to employ staking and layout control inspector acceptable to Engineer

NA

Contractor to employ site grading inspector acceptable to Engineer NA

Contractor to employ pavement work inspector acceptable to Engineer NA

Contractor to notify Engineer for approval

after subgrade preparation, before construction of porous media bed

Contractor to notify Engineer for approval

after choker course placed, before placement of pavement



shall not be used to dust truck beds. The open graded mix shall be covered during transportation with a suitable material of such size sufficient to protect the mix from the weather and also minimize mix cooling and the prevention of lumps. When necessary, to ensure the delivery of material at the specified temperature, truck bodies shall be insulated, and covers shall be securely fastened. Long hauls, particularly those in excess of 25 miles (40 km), may result in separation of the mix and its rejection.

3. Placing Equipment.

The paver shall be a self-propelled unit with an activated screed or strike-off assembly, capable of being heated if necessary, and capable of spreading and finishing the mixture without segregation for the widths and thicknesses required. In general, track pavers have proved superior for Porous Asphalt placement. The screed shall be adjustable to provide the desired cross-sectional shape. The finished surface shall be of uniform texture and evenness and shall not show any indication of tearing, shoving, or pulling of the mixture. The machine shall, at all times, be in good mechanical condition and shall be operated by competent personnel. Pavers shall be equipped with the necessary attachments, designed to operate electronically, for controlling the grade of the finished surface. The adjustments and attachments of the paver will be checked and approved by the Engineer before placement of asphalt material. Pavers shall be equipped with a sloped plate to produce a tapered edge at longitudinal joints. The sloped plate shall be attached to the paver screed extension. The sloped plate shall produce a tapered edge having a face slope of 1:3 (vertical: horizontal). The plate shall be so constructed as to accommodate compacted mat thickness from 35 to 100 mm (1 1/4 to 4 inches). The bottom of the sloped plate shall be mounted 10 to 15 mm (3/8 to 1/2 inch) above the existing pavement. The plate shall be interchangeable on either side of the screed. Pavers shall also be equipped with a joint heater capable of heating the longitudinal edge of the previously placed mat to a surface temperature of 95 °C (200 °F), or higher if necessary, to achieve bonding of the newly placed mat with the previously placed mat. This shall be done without undue breaking or fracturing of aggregate at the interface. The surface temperature shall be measured immediately behind the joint heater. The joint heater shall be equipped with automated controls that shut off the burners when the pavement machine stops and reignite them with the forward movement of the paver. The joint heater shall heat the entire area of the previously placed wedge to the required temperature. Heating shall immediately precede placement of the asphalt material.

4. Rollers.

Rollers shall be in good mechanical condition, operated by competent personnel, capable of reversing without backlash, and operated at speeds slow enough to avoid displacement of the asphalt mixture. The mass (weight) of the rollers shall be sufficient to compact the mixture to the required density without crushing of the aggregate. Rollers shall be



equipped with tanks and sprinkling bars for wetting the rolls.

Rollers shall be two-axle tandem rollers with a gross mass (weight) of not less than 7 metric tons (8 tons) and not more than 10 metric tons (12 tons) and shall be capable of providing a minimum compactive effort of 44 kN/m (250 pounds per inch) of width of the drive roll. All rolls shall be at least 1 m (42 inches) in diameter. A rubber tired roller will not be required on the open graded asphalt friction course surface.

5. Conditioning of Existing Surface.

Contact surfaces such as curbing, gutters, and manholes shall be painted with a thin, uniform coat of Type RS-1 emulsified asphalt immediately before the asphalt mixture is placed against them.

6. Temperature Requirements.

The temperature of the asphalt mixture, at the time of discharge from the haul vehicle and at the paver, shall be between 135-163°C (275 to 325°F), within 6 °C (10 °F) of the compaction temperature for the approved mix design.

7. Spreading and Finishing.

The Porous Asphalt shall be placed either in a single application at 4 inches (10 cm) thick or in two lifts. If more than one lift is used, great care must be taken to insure that the porous asphalt layer join completely. This means: keeping the time between layer placements minimal; keeping the first layer clear from dust and moisture, and minimizing traffic on the first layer. The Contractor shall protect all exposed surfaces that are not to be treated from damage during all phases of the pavement operation.

The asphalt mixture shall be spread and finished with the specified equipment. The mixture shall be struck off in a uniform layer to the full width required and of such depth that each course, when compacted, has the required thickness and conforms to the grade and elevation specified. Pavers shall be used to distribute the mixture over the entire width or over such partial width as practical. On areas where irregularities or unavoidable obstacles make the use of mechanical spreading and finishing equipment impractical, the mixture shall be spread and raked by hand tools. No material shall be produced so late in the day as to prohibit the completion of spreading and compaction of the mixture during daylight hours, unless night paving has been approved for the project. No traffic will be permitted on material placed until the material has been thoroughly compacted and has been permitted to cool to below 38 °C (100 °F). The use of water to cool the pavement is not permitted. The Engineer reserves the right to require that all work adjacent to the pavement, such as guardrail, cleanup, and turf establishment, is completed prior to placing the wearing course when this work could cause damage to the pavement. On projects where traffic is to be maintained, the Contractor shall schedule daily pavement



operations so that at the end of each working day all travel lanes of the roadway on which work is being performed are paved to the same limits. Suitable aprons to transition approaches, where required, shall be placed at side road intersections and driveways as directed by the Engineer.

8. Compaction.

Immediately after the asphalt mixture has been spread, struck off, and surface irregularities adjusted, it shall be thoroughly and uniformly compacted by rolling. The compaction objective is 16% - 19% in place void content (Corelock). Breakdown rolling shall occur when the mix temperature is between 135-163°C (275 to 325°F). Intermediate rolling shall occur when the mix temperature is between 93-135°C (200 to 275°F). Finish rolling shall occur when the mix temperature is between 66-93°C (150 to 200°F). The cessation temperature occurs at approximately 79°C (175°F), at which point the mix becomes resistant to compaction. If compaction has not been done at temperatures greater than the cessation temperature, the pavement will not achieve adequate durability. The surface shall be rolled when the mixture is in the proper condition and when the rolling does not cause undue displacement, cracking, or shoving. Rollers or oscillating vibratory rollers, ranging from 8-12 tons, shall be used for compaction. The number, mass (weight), and type of rollers furnished shall be sufficient to obtain the required compaction while the mixture is in a workable condition. Generally, one breakdown roller will be needed for each paver used in the spreading operation. To prevent adhesion of the mixture to the rolls, rolls shall be kept moist with water or water mixed with very small quantities of detergent or other approved material. Excess liquid will not be permitted. Along forms, curbs, headers, walls, and other places not accessible to the rollers, the mixture shall be thoroughly compacted with hot or lightly oiled hand tampers, smoothing irons or with mechanical tampers. On depressed areas, either a trench roller or cleated compression strips may be used under the roller to transmit compression to the depressed area. Other combinations of rollers and/or methods of compacting may be used if approved in writing by the Engineer, provided the compaction requirements are met. Unless otherwise specified, the longitudinal joints shall be rolled first. Next, the Contractor shall begin rolling at the low side of the pavement and shall proceed towards the center or high side with lapped rollings parallel to the centerline. The speed of the roller shall be slow and uniform to avoid displacement of the mixture, and the roller should



be kept in as continuous operation as practical. Rolling shall continue until all roller marks and ridges have been eliminated. Rollers will not be stopped or parked on the freshly placed mat. It shall be the responsibility of the Contractor to conduct whatever process control the Contractor deems necessary. Acceptance testing will be conducted by the Engineer using cores provided by the Contractor.

Any mixture that becomes loose and broken, mixed with dirt, or is in any way defective shall be removed and replaced with fresh hot mixture. The mixture shall be compacted to conform to the surrounding area. Any area showing an excess or deficiency of binder shall be removed and replaced. These replacements shall be at the Contractor’s expense. If the Engineer determines that unsatisfactory compaction or surface distortion is being obtained or damage to highway components and/or adjacent property is occurring using vibratory compaction equipment, the Contractor shall immediately cease using this equipment and proceed with the work in accordance with the fifth paragraph of this subsection. The Contractor assumes full responsibility for the cost of repairing all damages that may occur to roadway or parking lot components and adjacent property if vibratory compaction equipment is used. After final rolling, no vehicular traffic of any kind shall be permitted on the surface until cooling and hardening has taken place, and in no case within the first 48 hours. For small batch jobs, curing can be considered to have occurred after the surface temperature is less than 100 ºF (38 ºC). Curing time is preferably one week, or until the entire surface temperature cools below 100 ºF (38 ºC). Provide barriers as necessary at no extra cost to the Owner to prevent vehicular use; remove at the discretion of the Engineer.

9. Joints. Joints between old and new pavements or between successive day’s work shall be made to ensure a thorough and continuous bond between the old and new mixtures. Whenever the spreading process is interrupted long enough for the mixture to attain its initial stability, the paver shall be removed from the mat and a joint constructed. Butt joints shall be formed by cutting the pavement in a vertical plane at right angles to the centerline, at locations approved by the Engineer. The Engineer will determine locations by using a straightedge at least 4.9 m (16 feet) long. The butt joint shall be thoroughly coated with Type RS-1 emulsified asphalt just prior to depositing the pavement mixture when pavement resumes. Tapered joints shall be formed by tapering the last 450 to 600 mm (18 to 24 inches) of the course being laid to match the lower surface. Care shall be taken in raking out and discarding the coarser aggregate at the low end of the taper, and in rolling the taper. The taper area shall be thoroughly coated with Type RS-1 emulsified asphalt just prior to resuming pavement. As the paver places new mixture on the taper area, an evenly



graduated deposit of mixture shall complement the previously made taper. Shovels may be used to add additional mixture if necessary. The joint shall be smoothed with a rake, coarse material discarded, and properly rolled.

Longitudinal joints that have become cold shall be coated with Type RS-1 emulsified asphalt before the adjacent mat is placed. If directed by the Engineer, joints shall be cut back to a clean vertical edge prior to applying the emulsion.

10. Surface Tolerances.

The surface will be tested by the Engineer using a straightedge at least 4.9 m (16 feet) in length at selected locations parallel with the centerline. Any variations exceeding 3 mm (1/8 inch) between any two contact points shall be satisfactorily eliminated. A straightedge at least 3 m (10 feet) in length may be used on a vertical curve. The straightedges shall be provided by the Contractor. Work shall be done expertly throughout, without staining or injury to other work. Transition to adjacent impervious asphalt pavement shall be merged neatly with flush, clean line. Finished pavement shall be even, without pockets, and graded to elevations shown on drawing. Porous pavement beds shall not be used for equipment or materials storage during construction, and under no circumstances shall vehicles be allowed to deposit soil on paved porous surfaces.

11. Repair of Damaged Pavement. Any existing pavement on or adjacent to the site that has been damaged as a result of construction work shall be repaired to the satisfaction of the Engineer without additional cost to the Owner.

12. Striping Paint

Vacuum and clean surface to eliminate loose material and dust. Paint 4 inch wide parking striping and traffic lane striping in accordance with layouts of plan. Apply paint with mechanical equipment to produce uniform straight edges. Apply in two coats at manufacturer's recommended rates. Provide clear, sharp lines using white traffic paint Color for Handicapped Markings: Blue

C. QC/QA for Paving Operations

1. The full permeability of the pavement surface shall be tested by application of clean water at the rate of at least 5 gpm (23 lpm) over the surface, using a hose or other distribution devise. Water used for the test shall be clean, free of suspended solids and deleterious liquids and will



be provided at no extra cost to the Owner. All applied water shall infiltrate directly without large puddle formation or surface runoff, and shall be observed by the Engineer.

2. Testing and Inspection: Employ at Contractor's expense an inspection firm acceptable to the Engineer to perform soil inspection services, staking and layout control, and testing and inspection of site grading and pavement work. Inspection and list of tests shall be reviewed and approved in writing by the Engineer prior to starting construction. All test reports must be signed by a licensed Engineer.

3. Test in-place base and surface course for compliance with requirements for thickness and surface smoothness. Repair or remove and replace unacceptable work as directed by the Engineer.

4. Surface Smoothness: Test finished surface for smoothness using a 10 foot straightedge applied parallel with and at right angles to the centerline of the paved area. Surface will not be accepted if gaps or ridges exceed 3/16 of an inch.

5. QC/QA requirements during paving are summarized in Error! Reference source not found..

Table 9. QC/QA requirements during paving.

PART 4. REFERENCES CalTrans, January 2003, California Stormwater BMP Handbook 3 of 8 New Development and

Redevelopment, California Dept. of Transportation, Sacramento, CA www.cabmphandbooks.com

USEPA, September, 1999, Storm Water Technology Fact Sheet: Infiltration Drainfields, Number:

832F99018 USEPA, Office of Water, Washington, DC http://www.epa.gov/npdes/pubs/infltdrn.pdf

USEPA, September 2004, Stormwater Best Management Design Guide: Volume 1 General

Considerations, Office of Research and Development, EPA/600/R-04/121, Washington, D.C.

Vermont Agency of Transportation, 2006, 2006 Standard Specifications for Construction Book,

Division 700, Section 708, Montpelier, VT.

Activity Schedule/ Frequency Tolerance

Inspect truck beds for pooling (draindown) every truck NA

Take surface temp. behind joint heater each pull 6°C (10°F) of compaction temp

Consult with Engineer to determine locations of butt joints as needed NA

Test surface smoothness & positive drainage with a 10 ft straightedge

after compaction 4.5 mm (3/16")

Consult with Engineer to mark core locations for QA testing

after compaction NA

Hose test with at least 5 gpm water after compaction

immediate infiltation, no puddling



http://www.aot.state.vt.us/conadmin/2006StandardSpecs.htm Wisconsin Department of Natural Resources, Feb. 2004, Site Evaluation for Stormwater

Infiltration(1002), Wisconsin Department of Natural Resources Conservation Practice Standards Madison, WI

Appendix ESecure Site ...Three (3) test borings were drilled with two (2) of the test borings used...

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Transcript of Appendix ESecure Site ...Three (3) test borings were drilled with two (2) of the test borings used...