5.6 Hydrology and Water Quality - UCSB Hydrology and Water... · Storke Wetlands/Goleta Slough...

San Joaquin Apartments and Precinct Improvements Project EIR Hydrology and Water Quality

University of California, Santa Barbara

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5.6 HYDROLOGY AND WATER QUALITY

This section evaluates impacts to hydrologic and water quality conditions that could result from the implementation of the San Joaquin Apartments project. The evaluation of project-related impacts is based on information provided in a report titled UCSB San Joaquin Apartments Project EIR, Hydrology & Water Quality Technical Report (2013), prepared by Fuscoe Engineering. A copy of the technical report is provided in Appendix E of this EIR.

5.6.1 Setting Existing Drainage Conditions and Watersheds

The San Joaquin Apartments project site encompasses has been extensively developed with 10- and 11-story residential buildings; the podium building between the two tower buildings; paved vehicle and bicycle parking areas; and recreation facilities such as tennis courts, a swimming pool and deck area. Undeveloped areas on the project site generally consist of ornamental landscaping and an approximately two-acre mowed turf area on the eastern portion of the project site. An existing 1.5-acre turf area on the west side of Storke Road across the street from the project site would be used to develop a new parking lot. Drainage Conditions. The San Joaquin project would result in new development within two separate watersheds. The Santa Catalina Residence/proposed project site is within the Storke Wetlands/Goleta Slough Watershed. Runoff from the project site generally drains in northeasterly direction and discharges from the site through a storm drain system with two primary lines. These two lines join together underground in the open space parcel east of and adjacent to the project site. Flows from the project site remain in the underground storm drain system bypassing the open space parcel and are discharged into the Storke Wetlands after crossing underneath an access road that leads to Mesa Road and the Storke Family Student housing complex. Although the open space parcel to the east does not receive flows from the project site, it does accept runoff from a portion of the Isla Vista community through a 36-inch reinforced concrete pipe. Flows from Isla Vista discharge into two swales that drain water to the northeastern portion of the open space area where a large depression exists. Once the depressed area becomes full, flows drain under the access road through a culvert into the Storke Wetlands.

The second component of the project is a smaller 1.5-acre grass lot that would be used for the development of a proposed parking lot. The grass area is physically separated from the project site by Storke Road. This grass area is within the Devereux Creek Watershed and drains north and eventually into Devereux Creek just upstream of the tidally influenced Devereux Slough.

Storke Wetlands / Goleta Slough. The Storke Wetlands cover approximately 20 acres and are located along the northern perimeter of the Storke Campus, a minimum of approximately 800 feet northeast of the project site. The wetlands are oriented in an east-west direction, and are bisected by Los Carneros Road. The wetlands drain from east to west and are hydrologically connected to the Goleta Slough. The larger Storke Wetland watershed is approximately 347



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acres including the northern portion of Isla Vista, Storke Campus and a small narrow portion of the City of Goleta adjacent to Tecolotito Creek.

The Goleta Slough is a 430-acre area that resides within a 28,806 acre watershed consisting of several tributaries including Tecolotito, Carneros and Atascadero Creeks. The 430-acre wetland is located north of Main Campus approximately 3,000 feet northeast of the project site, and is almost entirely surrounded by development. The Slough receives runoff from UCSB Storke Campus, the northern portion of Main Campus and the More Mesa area east of UCSB.

Devereux Creek / Devereux Slough. The Devereux Slough is located on the UCSB West Campus and is approximately 45 acres within a 2,240-acre watershed. The Devereux Slough is primarily fed by Devereux Creek, which enters the Slough from the north. The lower portion of the Devereux Creek watershed is substantially built out while the upper portion consists of primarily native vegetation and agricultural land uses. Flows from the proposed parking lot area enter the Devereux Creek approximately 600 feet upstream of the Devereux Slough. Existing Hydrology Conditions The existing runoff conditions associated with the project site were analyzed to determine existing peak flow rates and volumes resulting from commonly analyzed storm event conditions. The software program HydroCAD (Stormwater Modeling version 10.0) was used, which is an acceptable software to use for peak flows and volumes in accordance with Santa Barbara County Flood Control & Water Conservation District and Water Agency protocols.

Under existing conditions, the San Joaquin Apartment project site is mostly impervious (approximately 77%) with the exception of the existing turf area on the east side of the project site. Impervious areas consist of large at grade parking lots, two multi-story buildings, tennis courts, a dining hall, pool and deck, maintenance facility and pedestrian/bike paths. Under existing condition, the site contains six (6) drainage areas and two primary discharge storm drain lines that drain the site. The major storm drain system pipes connect in the open space area east of the project site and west of the Storke Wetland, and cross under an access road running north/south before outletting into a linear degraded channel tributary to the larger Storke Wetland.

The project also includes the development of a parking lot on the west side of Storke Road. The parking lot site is a maintained turf area that drains south to north. The easterly one half of the grass drains northeasterly towards Storke Road, flows along the west side of street, crosses the West Campus Family Apartments driveway entrance, enters into a swale along the west side of Storke Road shoulder, and discharges into a wetland area on the former Ocean Meadows Golf Course. It then flows in a southwesterly direction and outlets into the Devereux Slough.

The runoff from the western portion of the grass area flows northwesterly, enters into the existing West Campus Family Apartments’ northerly driveway, flows west, turns south and then



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enters an existing swale on the west side of the apartments. This swale flows south and discharges to an existing storm drain under Venoco Road and then into Devereux Slough.

Table 5.6-1 provides a summary of the existing condition peak flows and volumes for a range of storm events for the Apartment Site and the parking lot.

Table 5.6-1 Existing Conditions Peak Flows and Volumes

Apartment Site Parking Lot Site

Storm Event

Existing Q (cfs)

Existing Volume (ac-ft)

Storm Event

Existing Q (cfs)


1-year 30.43 1.99 1-year 2.57 0.14

2-year 39.04 2.71 2-year 4.09 0.22

5-year 49.85 3.65 5-year 6.16 0.33

10-year 58.71 4.42 10-year 7.88 0.43

25-year 70.40 5.45 25-year 10.19 0.55

50-year 79.11 6.21 50-year 11.91 0.65

100-year 87.33 6.99 100-year 13.65 0.75

Notes: cfs cubic feet per second ac-ft acre-feet Q flow

100-Year Flood Areas

The Federal Emergency Management Agency Flood Insurance Rate Map for the project area indicates that the project site is not located in a 100-year flood area. The nearest designated flood area is located in low-lying areas, including the Storke Wetlands and Goleta Slough, a minimum of approximately 800 feet northeast of the site (UCSB, 2010).

Groundwater Conditions

Groundwater at UCSB occurs primarily as perched groundwater and is not a potable

resource. Perched groundwater is created when water percolates through permeable terrace deposits until it encounters relatively impermeable siltstone and shale bedrock formations. The quality of this groundwater is generally poor, with very high levels of total dissolved solids that exceed drinking water standards. Groundwater at the project site was encountered at depths of approximately 15 to 20 feet below the ground surface during recent geological investigations (Fugro, 2012).

Regulatory Setting Stormwater management and water quality regulations applicable to the proposed project are briefly described below.



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Clean Water Act. The federal Clean Water Act (CWA) was adopted in 1972 and provides the regulatory framework for surface water quality protection. The United States Congress amended the CWA in 1987 to specifically regulate discharges to waters of the US from public storm drain systems and storm water flows from industrial facilities, including construction sites, and require such discharges be regulated through permits under the National Pollutant Discharge Elimination System (NPDES). Rather than setting numeric effluent limitations for storm water and urban runoff, CWA regulation calls for the implementation of Best Management Practices (BMPs) to reduce or prevent the discharge of pollutants from these activities to the Maximum Extent Practicable (MEP) for urban runoff and meeting the Best Available Technology Economically achievable (BAT) and Best Conventional Pollutant Control Technology (BCT) standards for construction storm water. Regulations and permits have been implemented at the federal, state, and local level to form a comprehensive regulatory framework to serve and protect the quality of the nation’s surface water resources.

Porter-Cologne Water Quality Act. In the State of California, the State Water

Resources Control Board (SWRCB) and local Regional Water Quality Control Boards (RWQCBs) have assumed the responsibility of implementing US EPA’s NPDES Program and other programs under the CWA such as the Impaired Waters Program and the Antidegradation Policy. The primary quality control law in California is the Porter-Cologne Water Quality Act (Water Code Sections 13000 et seq.). Under Porter-Cologne, the SWRCB issues joint federal NPDES Storm Water permits and state Waste Discharge Requirements (WDRs) to operators of municipal separate storm sewer systems (MS4s), industrial facilities, and construction sites to obtain coverage for the storm water discharges from these operations.

California Coastal Commission. The California Coastal Commission is responsible for

protecting water quality in coastal environments as defined under Sections 30230 and 30231 of the California Coastal Act. These water quality provisions provide a broad basis for protecting coastal waters, habitats and biodiversity associated with new development and redevelopment projects. To meet the objectives of Sections 30230 and 30231, the Coastal Commission supports a three-pronged approach to water quality management: site design, source control and treatment control, and BMPs.

Basin Plan for the Central Coast Region. In addition to its permitting programs, the

SWRCB, through its nine RWQCBs, developed Regional Water Quality Control Plans (or Basin Plans) that designate beneficial uses and water quality objectives for California’s surface waters and groundwater basins, as mandated by both the CWA and the state’s Porter-Cologne Water Quality Control Act. Water quality standards are thus established in these Basin Plans and provide the foundation for the regulatory programs implemented by the state. The Central Coast RWQCB’s Basin Plan (June 2011), which covers UCSB, specifically (i) designates beneficial uses for surface waters and ground waters, (ii) sets narrative and numerical objectives that must be met in order to protect the beneficial uses and conform to the state’s antidegradation policy, and (iii) describes implementation programs to protect all waters in the Region. In other words, the Central Coast RWQCB Basin Plan provides all relevant information necessary to carry out federal mandates for the antidegradation policy, 303(d) listing of impaired waters, and related TMDLs, and provides information relative to NPDES and WDR permit limits.



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CWA Section 303(d) List of Water Quality Limited Segments. Under Section 303(d) of the CWA, states are required to identify water bodies that do not meet their water quality standards. Once a water body has been listed as impaired, a Total Maximum Daily Load (TMDL) for the constituent of concern (pollutant) must be developed for that water body. A TMDL is an estimate of the daily load of pollutants that a water body may receive from point sources, non-point sources, and natural background conditions (including an appropriate margin of safety), without exceeding its water quality standard. Those facilities and activities that are discharging into the water body, collectively, must not exceed the TMDL.

The UCSB campus is located within two primary watersheds including the Goleta Slough and the Devereux Slough. The project site also falls within both watersheds. In accordance with the 2010 USEPA Approved 303(d) Impaired Water Body List, the Goleta Slough/Estuary is listed for pathogens and priority organics. Devereux Creek is also listed for pathogens.

Total Maximum Daily Loads (TMDLs). Once a water body has been listed as impaired

on the 303(d) list, a TMDL for the constituent of concern (pollutant) must be developed for that water body. A TMDL is an estimate of the daily load of pollutants that a water body may receive from point sources, non-point sources, and natural background conditions (including an appropriate margin of safety), without exceeding its water quality standard. Those facilities and activities that are discharging into the water body, collectively, must not exceed the TMDL. In general terms, municipal, small MS4, and other dischargers within each watershed are collectively responsible for meeting the required reductions and other TMDL requirements by the assigned deadline.

For Goleta Slough, there is a TMDL establishment date of 2013 for pathogens and 2021 for priority organics. For Devereux Creek, there is a TMDL establishment date of 2013 for pathogens. At this time, the Central Coast Regional Board has not started on these TMDL’s and neither is in the development phase. TMDL development is expected within the next few years.

General Construction Permit (GCP) and Storm Water Pollution Prevention Plans

(SWPPPs). The General Construction Permit (GCP), Order No. 2009-0009-DWQ, NPDES Permit No. CAS000002, updated by the SWRCB in September 2009, regulates storm water and non-storm water discharges associated with construction activities disturbing 1 acre or greater of soil. Construction sites that qualify must submit a Notice of Intent (NOI) to gain permit coverage or otherwise be in violation of the CWA and California Water Code.

The GCP requires the development and implementation of a Storm Water Pollution Prevention Plan (SWPPP) for each individual construction project greater than or equal to 1 acre of disturbed soil area (regardless of the site’s Risk Level). The SWPPP must list Best Management Practices (BMPs) that the discharger will use to control sediment and other pollutants in storm water and non-storm water runoff; the BMPs must meet the BAT and BCT performance standards. Additionally, the SWPPP must contain a visual monitoring inspection program; a chemical monitoring program for sediment and other "non-visible" pollutants to be implemented based on the Risk Level of the site, as well as inspection, reporting, training and record-keeping requirements. Section XVI of the GCP describes the elements that must be contained in a SWPPP.



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In addition to the requirements described above, Order No. 2009-0009-DWQ contains

requirements for construction sites based on the site’s risk of discharging construction-related pollutants, as well as additional monitoring and reporting requirements. Each construction project must complete a Risk Assessment prior to commencement of construction activities, which assigns a Risk Level to the site and determines the level of water quality protection/requirements the site must comply with. The Permit also includes provisions for meeting specific Numerical Effluent Limits (NELs) and Numeric Action Levels (NALs) for pollutants based on the sites’ Risk Level.

Since the proposed project would disturb greater than one acre of land, the project is subject to the storm water discharge requirements of the GCP. The project will require submittal of an NOI, SWPPP, Risk Assessment, and other Project Registration Documents (PRDs) required by the GCP prior to the commencement of soil disturbing activities. The SWRCB is the permitting authority, while the Central Coast RWQCB provides local oversight and enforcement of the GCP.

Central Coast Joint Effort for Low Impact Development and Hydromodification

Control. The Central Coast Joint Effort for Low Impact Development (LID) and Hydromodification Control is a collaborative, region-wide approach within the Central Coast Regional Board jurisdiction that municipalities are using to implement LID and hydromodification control. The Storm Water Management Programs (SWMPs) for each municipality participating in the Joint Effort contain specific Best Management Practices (BMPs) pertaining to the Joint Effort. These BMPs fall into two categories: development of hydromodification control criteria, and implementation of hydromodification controls and LID.

Low impact development (LID) refers to runoff water management methods that minimize stormwater pollutants, reduce stormwater runoff rates and volumes, and promote groundwater infiltration and stormwater reuse in an integrated approach to protecting water quality and managing water resources. Objectives of LID include the implementation of measures that mimic undeveloped stormwater and urban runoff rates and volumes; prevent pollutants of concern from leaving a development site in stormwater; and minimize hydromodification impacts to natural drainage systems.

Hydromodification effects often result from urban development and associated increases

in impermeable area, and can include increased stormwater runoff volume, velocity, temperature and discharge duration. Hydromodification can also result in increased erosion and sedimentation and may also contribute to increases in nutrients, pathogens, pesticides, metals hydrocarbons organic debris and litter in runoff water.

As part of the Joint Effort, the Central Coast Regional Water Quality Control Board (RWQCB) developed Draft Resolution No. R3-2013-0032 titled Approving Post-Construction Stormwater Management Requirements for Development Projects in the Central Coast Region (Draft Resolution). The Resolution is consistent with the Phase II MS4 Stormwater Requirements for the Region (Order No. 2013-0001 DWQ) that were adopted on February 5, 2013 and became effective on July 1, 2013.



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Within the Resolution and its attachments, specific hydromodification criteria and water

quality criteria are defined dependent upon location within the Central Coast Region. The purpose of the location-specific criteria is to identify the dominant watershed processes within the region and assign regulatory runoff and water quality standards that protect the watershed processes and receiving water quality objectives. The Board recognized that a “one-size fits all” approach was not technically sound and the use of watershed-specific criteria provides more appropriate requirements. The goal of the Joint Effort is to protect or restore beneficial uses that otherwise would be, or that already have been, adversely affected by stormwater management practices in urban areas. This is accomplished by identifying hydromodification control strategies for new urban development and redevelopment based on landscape characterization and analyses.

The Draft Resolution identifies Watershed Management Zones (WMZs) through the region. The urbanized portions of the Central Coast Region are categorized into ten (10) WMZs, based on common key watershed processes and receiving water type (creek, wetland, lake, nearshore waters, etc.). Each WMZ is aligned with specific post-construction stormwater management requirements to address the impacts of development on those watershed processes and beneficial uses.

The majority of the UCSB Campus is designated as WMZ-Zone 1. As part of the WMZ-Zone 1 water quality requirements, all projects must retain the 95th Percentile 24-hour rainfall event (2.17”) and compliance must be achieved via infiltration, and all regulated projects must manage peak stormwater runoff such that post-development peak flows, discharged from the site, shall not exceed peak flows for the 2- through 10-year storm events. The post-construction stormwater management requirements also identify performance criteria for Historical Lake and Wetland Special Circumstance scenarios. The Historic Lake and Wetland Special Circumstance criteria allow the Permittee to designated Regulated Projects as subject to Special Circumstances based on certain site and/or receiving water conditions. The Special Circumstances may allow specific runoff retention exemptions and/or peak management performance exemptions where the reduction in flows may have an adverse impact on the downstream receiving waters.

Specific to the Historic Lake and Wetland Special Circumstance, the San Joaquin

Apartments project is upstream of wetland receiving waters and retention requirements may not be recommended in order to preserve existing hydrologic flows. For the San Joaquin project, the Historic Lake and Wetland Special Circumstance may also apply as the existing soil is Type D (Source: Natural Resources Conservation District Web Soil Survey) with very little infiltration potential and did not likely provide infiltration under historical conditions.

University of California, Santa Barbara Stormwater Management Plan (2010).

UCSB has been designated by the State Water Resources Control Board as a non-traditional Phase II small municipal separate storm sewer system (MS4) and must abide by the most current MS4 Permit (Order No. 2013-0001). As a small MS4, the Campus is required to enroll in the State’s General NPDES Permit for storm water discharges, and must prepare a Storm Water Management Plan (SWMP) that meets criteria specified by the Central Coast RWQCB.



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In March 2010 UCSB prepared a Storm Water Management Plan that addresses six general control measures: 1) public education and outreach on stormwater impacts; 2) public involvement and participation; 3) illicit discharge detection and elimination; 4) construction site stormwater runoff control; 5) post-construction stormwater management in new development and redevelopment; and 6) pollution prevention/good housekeeping for facilities operation and maintenance. The SWMP identifies the following pollutants of concern associated with residential development including sediments, pathogens, hydrocarbons (oil and grease), pesticides, toxics (organics), nutrients and gross pollutants (litter, trash, debris).

SWMP Section 8.0, Post-Construction Stormwater Management in New Development and Redevelopment, focuses on hydromodification control. The purpose of the hydromodification control criteria are to protect beneficial uses of water resources and promote the desired conditions of healthy watersheds to the maximum extent practical, including:

Maximize infiltration of clean stormwater and minimize runoff volume and rate increases or reductions based on existing conditions.

Protect riparian areas, wetlands and their buffer zones.

Minimize pollutant loading.

Provide long-term watershed protection.

UCSB elected in November 2009 to participate in the Central Coast Joint Effort for Hydromodification and LID Control. Participation in the Joint Effort provided UCSB the flexibility to evaluate three different hydromodification options and select the one that best protects downstream receiving waters and wetlands while preserving necessary Campus improvements and new development and redevelopment projects. Option 3 was selected as the methodology that was the best fit for hydromodification control based on the location of the Campus. Although hydromodification is considered by the Central Coast RWQCB as a significant issue within the Central Coast region, it does not play a major role on the UCSB campus. Factors such as highly impermeable soils, susceptibility to bluff erosion and seepage, discharges into storm drains and hardened channels that flow directly into tidally influenced water bodies, and the minimal presence of substantial stream lengths preclude the need for highly prescriptive hydromodification criteria that do not reflect the individual watersheds susceptibility.

Option 3 Hydromodification Criteria includes a range of runoff flow rates for which post-project flow rates and durations shall not exceed pre-development runoff rates and durations based on pre-project conditions. Option 3 also includes establishment of numeric criteria for development/redevelopment projects to maximize infiltration on-site where applicable and effectively implement LID strategies and features. The approval of the Draft Resolution will require the UCSB to update the 2010 SWMP to reflect the most current LID design criteria while taking into consideration the site specific constraints.



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LRDP Requirements Water quality protection policies provided by the 2010 LRDP require that construction projects minimize and contain sediment and other pollutants. In general, the LRDP water quality protection policies pertain to minimizing the potential for erosion and sedimentation, preventing sediment from leaving project sites, minimizing vegetation removal, minimizing impacts from cut and fill slopes, and minimizing impacts to aquatic resources such as wetlands and the Campus Lagoon.

5.6.2 Impact Identification and Significance Thresholds Initial Study Evaluation of Potential Impacts Less Than Significant Impacts. The Initial Study prepared for the San Joaquin Apartments project concluded that the project would have the potential to affect water quality for several pollutants of concern identified by the UCSB Stormwater Management Plan, however, the project would not substantially contribute to existing pollutant loads or concentrations associated with pathogens, pesticides or toxics due to the residential nature of the project and the implementation of existing UCSB policies. No further evaluation of the identified pollutants is required. The Initial Study concluded that construction operations at the project site would have the potential to result in erosion and sedimentation impacts. However, the implementation of existing regulatory requirements and LRDP polices would reduce the potential for short-term water quality impacts to a less than significant level and no further evaluation of this impact is required. Additional information regarding the proposed project’s potential for construction-related erosion and sedimentation impacts is provided in EIR Appendix E. The information provided indicates that the proposed project could feasibly comply with General Construction Permit intended to minimize the construction-related erosion and sedimentation impacts. Groundwater resources in the vicinity of the project site are not used as a potable water source and the project would not result in the development of new structures that would be affected by a 100-year flood. Due to the inland location of the project site, it would not be adversely affected by a tsunami, and there are no nearby dams whose failure could result in flooding-related impacts. No further analysis of these issue areas is required. Potentially Significant Impacts. The hydrology and water quality impacts of the San Joaquin Apartments project identified by the Initial Study as requiring additional evaluation in an EIR include:

Long-term water quality impacts that could result from sediment, hydrocarbons, nutrients and gross pollutant (trash, litter, vegetative matter) discharges from the project site.



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Changes in stormwater discharge characteristics that could result in downstream hydromodification impacts.

The potential for increased stormwater discharges that could substantially contribute

to downstream flooding. The potential for increased stormwater discharges that could impact downstream

drainage facility capacity.

Impact Evaluation Significance Thresholds

The hydrology and water quality thresholds provided by Appendix G of the CEQA Guidelines that are applicable to the potential impacts of the San Joaquin Apartments project are listed below. The thresholds indicate that the proposed project would result in a significant environmental impact if it would:

1. Violate any water quality standards or waste discharge requirements.

2. Substantially alter the existing drainage pattern of the site or area, including through the

alteration of the course of a stream or river, or in a manner which would result in a substantial erosion or siltation on- or off-site.

3. Substantially alter the existing drainage pattern of the site or area, including through the

alteration of the course of a stream or river, or substantially increase the rate or amount of surface runoff in a manner that would result in flooding on- or off-site.

4. Create or contribute runoff water which would exceed the capacity of existing or planned

storm water drainage systems or provide substantial additional sources of polluted runoff.

5. Otherwise substantially degrade water quality.

5.6.3 Impact Evaluation

Hydrology

San Joaquin Apartments Project Site. The proposed project’s site plan and associated grading and storm drain plans were reviewed to assess post-project runoff conditions. The proposed project would remove the large impervious parking lots, develop additional buildings, provide landscaping, and install LID features. The proposed changes to the project site would result in a proposed impervious area of 57%, which would be a reduction in impervious area when compared to existing conditions. Table summarizes the peak flow and volumes for existing and proposed conditions and identifies the percent change for each.



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Table 5.6-2

Proposed Conditions Rates and Volumes for San Joaquin Apartments Site

Event Existing Q (cfs)

Proposed Q (cfs)


Proposed Volume (ac-ft)

Change (Q / Vol)

% Change (Q / Vol)

1-year 30.43 26.42 1.99 1.89 -4.0 / -0.1 -13.2% / -5.2%

2-year 39.04 36.18 2.71 2.59 -2.9 / -0.1 -7.3% / -4.4%

5-year 49.85 48.97 3.65 3.5 -0.9 / -0.1 -1.8% / -3.7%

10-year 58.71 59.35 4.42 4.3 +0.6 / -0.1 +1.1% / -3.3%

25-year 70.40 72.37 5.45 5.3 +2.0 / -0.2 +2.8% / -2.9%

50-year 79.11 80.70 6.21 6.05 +1.6 / -0.2 +2.0% / -2.7%

100-year 87.33 88.67 6.99 6.81 +0.8 / -0.2 +1.0% / -2.5%


The San Joaquin project site would be divided into 10 drainage areas with four outlet

points compared to the existing single underground outlet point. The San Joaquin Apartments project also includes the use of three small-scale detention basins or shallow ponds that would collect stormwater runoff from the four proposed discharge points. The proposed ponds would assist with stormwater discharge energy dissipation, and would provide additional flow attenuation and habitat benefits. The ponds would be located east of and adjacent to the San Joaquin apartments project site, to the west of jurisdictional wetland areas located on the open space area east of and adjacent to the project site, and would be located within the wetland buffer zones of the adjacent wetlands to the east. The ponds would be approximately two feet deep and oriented in a north to south direction. Based on the proposed top and bottom elevations of the ponds, the highest pond would be located at the southern portion of the site with a base elevation of 19 feet (top 21 feet), the middle pond would have a base elevation of 17 feet (top 19 feet) and the most northerly pond would have a base elevation 13 feet (top 15 feet). The location of the proposed ponds is depicted on Figure 4.4-1.

As currently proposed, the most southerly stormwater discharge pipe that would be located on the project site would convey stormwater into the middle pond, thereby leaving the southerly pond with only a minor sheet flow tributary area. To ensure that the southerly pond is utilized effectively, it is recommended that the proposed project site storm drain system be modified so that runoff from the southern portion of the San Joaquin site is discharged into the southerly pond. This recommendation is included in EIR Section 5.6.5 as measure HYD-3a. This is a recommended measure and its implementation is not required to reduce any drainage-related impacts to less than significant level.

The proposed pond stormwater inlets would be designed with scour and energy dissipation measures to prevent localized erosion within the ponds. As stormwater is discharged to the ponds they would fill, and after the capacity of the ponds is reached the water would slowly overtop and sheet flow onto the adjacent wetland buffers and wetland areas. Each of the



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ponds may also include subterranean pipes that would discharge collected water to an adjacent wetland buffer area. The use of subterranean discharge pipes would reduce overtopping and reduce sheet flow conditions near the ponds. Also, incorporation of drain pipes into the design of the ponds would reduce the likelihood of standing water, which can degrade water quality and introduce vector control (mosquito) issues. The proposed optional bike path that would be located near the southeast corner of the San Joaquin project site would be located between the northern pond and the two southerly ponds. The bicycle path would be at grade and may be subject to minor sheet flow conditions when the two southerly ponds overflow and drain towards the adjacent wetlands. The use of subterranean pipes to drain water from the ponds would minimize the occurrence of sheet flow over the bicycle path.

Sheet flow and/or drain pipe discharges from the ponds would discharge onto adjacent wetland buffer areas, and the water would be allowed to sheet flow to adjacent wetlands. Flows from the ponds or subterranean drain pipes must be discharged in a controlled manner (i.e. energy dissipation), otherwise the project site’s drainage system would have the potential to result in significant localized scour and erosion impacts at each discharge point, which in turn has the potential to result in significant erosion and downstream sedimentation and water quality impacts. This potential impact can be reduced to less than significant by proposed mitigation measure HYD-1a, which requires that appropriate energy dissipation be provided at each proposed discharge point.

Based on the small footprint and shallow depth of the proposed ponds, they would not substantially affect the proposed drainage conditions described on Table 5.6-2, which does not include flow attenuation provided by the ponds. In addition, the ponds would not substantially decrease stormwater flows to any wetland areas near the project site. The ponds would provide multiple benefits, including additional peak flow runoff control, decreased erosive conditions into wetland buffer zones, increased native habitat, and additional incidental water quality benefits. In addition, water retention provided by the ponds would also more closely mimic historical watershed conditions of shallow depressions that temporarily hold water before discharging to the downstream wetlands.

Under the proposed conditions, both runoff peak flow rates and associated stormwater volumes from the project site will remain under existing condition thereby satisfying all 2-year through 10-year runoff control requirements to the downstream receiving water in accordance with the Post-Construction Stormwater Management Requirements for Development Projects in the Central Coast Region. The 10-year storm event does show that flow rates will increase by 0.6 cfs but it should be noted that the estimated increase does not account for approximately one acre-foot of water storage volume to be provided on the project site for water quality treatment, which will provide additional flow attenuation through the proposed bioretention features and provide additional reduction of flows below existing conditions. By introducing project flows into the open space parcel to the east, additional storage, infiltration and evapotranspiration will occur that does not occur under existing conditions. This will result in a minor reduction in direct flows and water volumes to the Storke Wetland while providing additional hydrologic benefits to the wetland habitat within the adjacent open space parcel, which is hydrologically connected to the Storke Wetlands. Due to the decreases in flow and volumes, and the storm drain outlet modifications to the adjacent open space parcel, retention of the 95% storm event



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would have negative impacts on the hydrologic conditions downstream for smaller storm events, and biotreatment BMPs will be used to treat and release flows under controlled conditions. Hydrologic flows will remain similar to existing conditions based on the proposed storm drain system and biotreatment BMPs and impacts to the hydrologic conditions would be less than significant.

Proposed Parking Lot. Under the proposed conditions, flows from the proposed

parking lot would drain north within two vegetated earthen swales with underdrains to promote water quality treatment and flow attenuation. The westerly swale would be located between parking stalls and the easterly swale would be located along the east side of the parking lot. These two swales would slow the flow of water and outlet into the storm drain under the Sierra Madre Court driveway, which will be constructed as a part of the Sierra Madre Apartment Villages project. The Sierra Madre storm drain system is to run west along Sierra Madre Court, turn south, and outlet to an existing constructed swale along the west side of the West Campus Family Apartments. The swale discharges to an existing storm drain on Venoco Road and then into the Devereux Slough. The Sierra Madre Apartment Villages project is fully approved, funded and designed, and is expected to commence construction in the fall of 2013. If the Sierra Madre storm drain system has not been installed prior to the start of construction for the proposed parking lot, the drainage system would be constructed by the San Joaquin project.

Table 5.6-3 presents the changes in peak flow and volumes that would result from the

proposed parking lot.

Table 5.6-3 Proposed Conditions Peak Flow Rates and Volumes for the Proposed Parking Lot

Event Existing Q (cfs)

Proposed Q (cfs)


Proposed Volume (ac-ft)

Change (Q / Vol)

% Change (Q / Vol)

1-year 2.57 4.42 0.14 0.27 +1.9 / +0.13 +72% / +91%

2-year 4.09 5.79 0.22 0.36 +1.7 / +0.14 +41% / 62%

5-year 6.16 7.55 0.33 0.47 +1.4 / +0.14 +22% / +41%

10-year 7.88 8.97 0.43 0.56 +1.1 / +0.13 +14% / 31%

25-year 10.19 10.83 0.55 0.68 +0.6 / + 0.12 +6% / +22%

50-year 11.91 12.22 0.65 0.76 +0.3 / +0.11 +3% / +17%

100-year 13.65 13.60 0.75 0.85 -0.1 / 0.10 -05% / +13%


Under the proposed conditions, both runoff peak flow rates and associated storm volumes

from the parking lot site would increase when compared to existing conditions. In accordance with the Post-Construction Stormwater Management Requirements for Development Projects in the Central Coast Region, and WMZ 1 requirements, post-development peak flows shall not exceed pre-project peak flows for the 2- through 10-year storm events. Based on the evaluation



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results, on-site controls would be required to reduce peak flow rates up to the 10-year storm event in the range of 1.1 to 1.9 cfs to match existing conditions.

In lieu of on-site controls, the proposed parking lot drainage runoff rates have been accounted for in the UCSB Sierra Madre Apartments project drainage system design. The Sierra Madre hydrology study accounted for the proposed flows coming from the parking lot and demonstrated the peak flows discharging into Devereux Slough will be less than existing, thereby conforming with the Post-Construction Stormwater Management Requirements. This is primarily due to longer flow paths, the use of vegetated swales in lieu of traditional storm drain pipes, and extended time of concentration. No additional on-site controls are required and the proposed parking lot’s hydrologic impacts would be less than significant. Through the use of vegetated bioswales and longer times of concentration, impacts related to downstream erosion or siltation resulting from the proposed parking lot would also be less than significant.

Approximately half the stormwater flows from the parking lot area under existing

conditions would no longer drain towards a series of wetlands located north of the proposed parking lot adjacent to Storke Road due to the diversion of runoff into the Sierra Madre Apartment storm drain system. These wetlands are located west of Storke Road across the street from the Storke Ranch residential neighborhood. This diversion would result in a flow decrease ranging from approximately one cfs for a two-year event to 0.6 cfs for a 10-year event. Based on the review of the regional drainage conditions, the reduction of flow from approximately 0.8 acres of turf area under the existing condition represents less than one percent of the wetland’s watershed flows, which would not cause significant hydrologic impacts to the existing wetland hydrology. The majority of flows for these wetlands originates from the Storke Ranch residential development and those flows will remain unchanged. Downstream Flooding. Under the proposed conditions, the peak flows and volumes from the San Joaquin Apartments project site would be slightly reduced when compared to existing conditions. The design of the proposed storm drain system would also result in project site flows being discharged onto the open space parcel to the east, which would increase flows to the existing wetlands within the open space. This would result in a slight decrease in flow rates and volumes to the Storke Wetland due to minor storage, infiltration and evapotranspiration that will occur within the open space parcel. However, the Storke Wetlands and the open space parcel wetlands are hydrologically connected via a culvert and therefore, once flows fill in the shallow depressions within the open space, flows will drain through the culvert into Storke Wetlands. Therefore, the San Joaquin Apartments project would not substantially change existing flood conditions associated with the Storke Wetlands and would have a less than significant impact related to increasing the potential for downstream flooding.

The increase in flows from the proposed parking lot would be minimized by the design of the Sierra Madre Apartment project’s drainage system. This includes the incorporation of vegetated swales with underdrains to provide water quality treatment and flow attenuation such that proposed peak flows to Devereux Slough will be remain at existing conditions. Therefore, the proposed parking lot would have a less than significant impact related to increasing the potential for downstream flooding.



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Water Quality

To minimize long-term water quality impacts that could result from the San Joaquin Apartments project, and to comply with the requirements of the UCSB Storm Water Management Plan and the Joint Effort Hydromodification and LID Controls, the project must incorporate LID/site design and source control BMPs to address post-construction stormwater runoff management. Selection of appropriate LID and treatment control BMPs is based on the pollutants of concern and the BMP’s ability to effectively treat those pollutants in consideration of site conditions and constraints. Further, under the requirements of the Joint Effort, regulated Projects must develop a project-specific Stormwater Control Plan that describes the menu of BMPs chosen for the project, provide documentation certifying sufficient sizing and design and calculations, and identify operation and maintenance requirements for all structural and any treatment control BMPs. Regulated Projects include all new development and redevelopment that create and/or replace 2,500 square feet or more of impervious surface.

Pollutants of Concern. The UCSB SWMP identifies the following pollutants of concern associated with residential projects:

Sediment Pathogens Hydrocarbons (oil and grease, lubricants) Pesticides Toxics (organics, hazardous wastes) Nutrients Gross pollutants (litter, trash, debris) Sources of pathogens such as bacteria and viruses typically include animal wastes, human

encampments, and overflows from wastewater systems. The residential units and other facilities provided by the San Joaquin Apartments project would not facilitate keeping domestic pets, and domestic wastewater would be discharged to a sanitary sewer system. Therefore, the project would not be a substantial source of pathogens.

Pesticide use (including the use of insecticides, rodenticides, herbicides, fungicides and growth regulators) on the UCSB campus has been substantially reduced and UCSB has adopted an Integrated Pest Management (IPM) program for the inside and outside of all on-campus structures (UCSB Use of Pesticides Policy 5435). The UCSB Department of Housing and Residential Services has also implemented programs to limit pesticide use. Based on existing pesticide use practices implemented at UCSB, the proposed project site would not be a substantial source of pesticide-related pollutants.

The UCSB Stormwater Management Plan indicates that the primary source of toxic materials from on-campus residential facilities would be from the use of household hazardous materials. The use of hazardous materials at the San Joaquin Apartments project would be very limited, and would generally consist of items such as cleaners, paints and other similar substances. The proposed project would not be a substantial source of toxic substances.

The potential sources and effects of pollutants of concern that may be associated with the San Joaquin Apartments project are described below.



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Sediment. Sheet erosion and the transport and deposition of sediment in surface waters

can be a significant form of pollution that may result in water quality problems. Increases in runoff velocities and volumes can cause excessive stream erosion and sediment transport altering the sediment equilibrium of a stream or channel. Excessive fine sediment, such as total suspended solids, can impair aquatic life through changes to the physical characteristics of the stream (light reduction, temperature changes, etc.).

Hydrocarbons. The most common sources of hydrocarbons in residential areas is oil and grease from spilled fuels and lubricants, discharge of domestic wastes, atmospheric deposition, and runoff. Runoff can contain leachate from roads, breakdown of tires/rubber and deposition of automobile exhaust. Some petroleum hydrocarbons, such as polycyclic aromatic hydrocarbons (PAHs), can bioaccumulate in aquatic organisms and are toxic at low concentrations. Hydrocarbons can persist in sediment for long periods of time in the environment and can result in adverse impacts on the diversity and abundance of benthic communities.

Nutrients. Nutrients are inorganic forms of phosphorous and nitrogen. The main sources of nutrients in urban areas include fertilizers in lawns, pet wastes, failing septic systems, and atmospheric deposition from automobiles and industrial operations. The most common impact of excessive nutrient input is eutrophication of the receiving water body, resulting in excessive algal production, hypoxia or anoxia, fish kills and potential releases of toxins from sediment due to changes in water chemistry profiles.

Trash and Debris. Improperly disposed or handled trash such as paper, plastics and debris including the biodegradable organic matter such as leaves, grass cuttings, and food waste can accumulate on the ground surface where it can be entrained in urban runoff. The large amount of trash and debris can have significant negative impacts on the recreational value of water body. Excessive organic matter can create a high biochemical oxygen demand in a stream and lower its water quality. Proposed Water Quality Treatment Methods. The design of the San Joaquin Apartments project includes a variety of LID strategies and source control measures to provide treatment of stormwater and reduce runoff rates and volumes. Proposed LID features are evaluated below to assess their ability to adequately treat runoff from the project site. In accordance with the 2013 Draft Resolution and UCSB SWMP, the San Joaquin project would implement site design BMPs to minimize directly connected impervious areas and promote runoff through pervious areas. Site design measures that would be implemented by the project include:

Maximization of pervious surfaces including an increase in permeable surfaces over existing condition.

Incorporation of landscaped buffer areas between sidewalks and streets.



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Maximization of canopy interception and water conservation by preserving some existing native trees and shrubs, and planting additional native or drought tolerant trees and large shrubs.

Incorporation of landscaping for roof drainage and sidewalk runoff. The use of vegetated drainage swales in lieu of underground piping or imperviously

lined swales.

Many of the site design BMPs may also be considered LID features. These include directing runoff to vegetated areas, protecting existing vegetation, and reducing the amount of impervious surfaces.

Source Control BMPs. Source control BMPs minimize the potential for typical urban pollutants to come into contact with runoff, thereby limiting water quality impacts downstream. This includes both non-structural measures, such as activity restrictions, maintenance, and training practices; and structural measures, such as material storage area and loading dock design features. Source control BMPs to be implemented at project site and required by the UCSB SWMP include:

Education for residents and staff. Activity restrictions. Landscape management BMP maintenance Litter control Employee training Sweeping parking areas Storm drain labeling Efficient irrigation and landscape design

Low Impact Development BMPs. Unlike flood control measures that are designed to

handle peak storm flows, LID BMPs and treatment control BMPs are designed to retain, filter or treat more frequent, low-flow runoff or the “first-flush” runoff from storm events. In accordance with the Draft Resolution Post-Construction Requirements, the LID BMPs shall be sized and designed to ensure on-site retention of the volume of runoff produced from a 24-hour 95th percentile storm event, as determined from the Central Coast Region 95th Percentile Precipitation Map, which is equal to 2.17 inches at the project site. This is termed the “stormwater treatment volume.”

Infiltration BMPs. Infiltration BMPs include facilities such as infiltration trenches, infiltration basins, drywells, underground infiltration units, unlined permeable pavement and bioretention cells without underdrains. When properly designed to store and infiltrate the entire treatment volume, infiltration BMPs are considered highly effective at treating pollutants of concern from a project site. However, the 2010 SWMP recognizes several limitations to infiltration at UCSB including the project site. Based on the Natural Resources Conservation



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Service (NRCS) Hydrologic Soil Groups web soil survey, the site has type D soils which are not considered suitable for large-scale infiltration BMPs that incorporate ponding depths of 1 foot or more to infiltration stormwater volumes. The use of permeable pavement is considered feasible assuming the effective depth (total depth of water stored in the subterranean reservoir) is kept rather shallow so water can drain out within 48 hours based on the soil infiltration rate.

The project proposes the use of permeable pavements spread out over the project site in approximately six (6) areas. Site specific soil infiltration tests are recommended by proposed mitigation measure HYD-2a to determine the allowable storage reservoir depth and the amount of storm water treatment volume that can be infiltrated into the soil within 48-72 hours. For conservative evaluation purposes, the storm water treatment calculations attributable to the proposed use of permeable pavement at the project site has assumed a 12” reservoir depth (effective depth of 0.4’) to ensure runoff captured within the reservoir drains into native soils within 48-72 hours following a rain event. If soil infiltration testing determines permeable pavement is not feasible, the site bioretention features are sufficiently sized to meet the water quality volume requirements.

Evapotranspiration BMPs. Evapotranspiration BMPs primarily include green roofs (vegetated roofs) or blue roofs (storage of storm water on rooftops). The proposed project has proposed the use of “intensive” green roofs and covered sundecks on certain buildings. Intensive green roofs have thicker soil depths and can support a larger variety of plants as compared to extensive roofs which incorporate much shallower soil depths and plants. Intensive green roof require additional structural support. Biotreatment BMPs. For project sites with low soil permeability characteristics, such as conditions found at the San Joaquin project site, biotreatment BMPs such as bioretention facilities with underdrains are utilized for treatment of the stormwater volumes. These BMPs differ from infiltration in that runoff is treated and released from the project site, rather than retained on-site. This also allows downstream wetlands and creeks to maintain existing flows after runoff treatment has been provided. Examples of biotreatment BMPs include bioretention cells and bioswales with underdrains, constructed wetlands, and proprietary modular bioretention systems. Biotreatment is considered feasible for the San Joaquin project.

The proposed project site plan includes 18 bioretention with underdrain features located throughout the project site to provide stormwater treatment for existing buildings and the proposed project buildings. The use of such features combined with the permeable pavements results in a significant amount of land use dedicated for water quality purposes (approximately 14%).

For the proposed parking lot on the west side of Storke Road, two bioretention with

underdrain facilities would be provided. The project design incorporates the use of these features to receive sheet flow from the parking lot surfaces and provide treatment and flow attenuation of small storm events prior to reaching the proposed Sierra Madre Court storm drain system.



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Proposed Stormwater Treatment Capacity. To evaluate if the proposed LID features would be adequately sized for the runoff conditions that would exist after implementation of the proposed project, the storm water treatment requirements for the 95% 24-hour storm event were compared against the storage and treatment capacity of the proposed bioretention with underdrain and permeable pavement features. Table 5.6-4 summarizes the total treatment volume required for the 95% 24-hour storm event and the total storage and treatment capacity of the proposed LID features.

Table 5.6-4 Stormwater Volume Requirements and Proposed LID Volume Capacity

Project Area Acreage

95% 24-hour Storm Event

Volume

Permeable Pavement Acreage Provided

Bioretention Acreage provided

Permeable Pavement Storage

Volume(2)

Bioretention Storage

Volume(3)

Apartment Site

13.2 acres 57% Impervious(1)

45,306 ft3 24,786 ft2 34,020 ft3 9,914 ft3 48,308 ft3

Parking Lot Site

1.5 acres 95% Impervious

10,191 ft3 Not

Applicable 2,900 ft2

Not Applicable

2,922 ft3

Summary

Apartment Site Required Volume: 45,202 ft3 Total Treatment Provided: 58,222 ft3

Parking Lot Required Volume: 10,191 ft3 Total On-Site Treatment provided: 2,922 ft3

Notes: 1) Accounts for LID surfaces as pervious. 2) Permeable pavement assumes 1-ft storage reservoir for volume storage (1’ x 0.4 porosity = 0.4’) for a total effective storage of 0.4-ft

per square ft pavement section. 3) The acreage provided on the site plan dedicated to bioretention facilities provides more theoretical storage than accounted for in

Table 5.6-4. A reduction factor of 30% has been applied to take into account side slopes, grade differentials, utilities, and other constraints that ultimately affect the footprint available for bioretention.

For the proposed project site, the implementation of the proposed LID features will

satisfy the volume treatment requirements of the Draft Resolution. Due to the low infiltration potential, further site investigation may prohibit the use of permeable pavement or may require sub-drains to eliminate standing water in the sub-base for extended periods of time. In the event permeable pavement is eliminated from the project for geotechnical or performance reasons, the proposed volume of bioretention (accounting for the reduction factor) is sufficient to accommodate the project’s entire stormwater treatment requirement. In addition, infiltration constraints will also likely prohibit the ability to effectively infiltrate the entire volume via infiltration. Based on the need to maintain “treated” flows to the downstream wetland and creek similar to existing conditions, and the lack of hydromodification potential downstream receiving waters, retention of the 95% storm event is not recommended. Biotreatment and discharge of clean water to downstream wetlands will maintain existing conditions and will not result in an increase of flows or volumes to the downstream receiving water.



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For the proposed parking lot site, the on-site bioretention features would provide partial treatment of the required stormwater volume. The remainder of the treatment requirements are incorporated into the Sierra Madre Apartment Villages project that is currently funded for construction starting in the fall of 2013. The design of the Sierra Madre Villages drainage system has accounted for the flow rates of stormwater runoff coming from the proposed parking lot. Peak runoff discharges from the Sierra Madre system to the Devereux Slough will not be increased due to longer time of concentration and the incorporation of vegetated drainage swales to provide flow attenuation. The results indicate that flows from the project site to the Devereux Slough would remain at or below existing conditions.

Based on the incorporation of site design, LID features and BMPs consistent with the

UCSB SWMP and Draft Resolution, implementation of the proposed project would result in less than significant increases in project runoff.

Pollutants of Concern. The ability of proposed LID features and BMPs to minimize

water quality impacts associated with pollutants of concern that may be associated with the proposed project is evaluated below.

Sediment. After occupancy of the proposed project, any sediment generated from site-

specific developments would be collected in the proposed LID features and BMPs, which are considered effective for the control of sediments typically associated with these impervious surfaces and pervious surfaces in residential areas. Field data indicates sediment removals in the range of 90% for bioretention based BMPs. As a result, sediment impacts to water quality are considered less than significant.

Hydrocarbons. The potential for oil and grease in runoff would be reduced under proposed conditions due to the removal of the large parking areas that currently exist on the project site. The project would result in the construction of a 1.5 acre parking lot, however, the design of the lot would include vegetated bioswales to help remove oil and grease from storm water runoff. Field data indicates oil and grease removals in the range of 80% for bioretention based BMPs. Project-related parking would also occur within an existing parking structure (Lot 50), which would reduce the amount of impervious surfaces exposed to rain. Hydrocarbon-related impacts to water quality as a result of the proposed project are less than significant.

Nutrients. Through the proper implementation of source control design measures, the use of native and drought-tolerant landscaping, irrigation controls, and infiltration/biotreatment BMPs, excessive nutrient loads from the project site are not expected to occur. Field data indicates nutrient pollutant removals in the range of 70% – 80% for phosphorous and 40% for nitrogen for bioretention based BMPs. Nutrients will not be contained in project runoff at levels that could adversely affect water quality or beneficial uses in downstream receiving waters and potential nutrient impacts are less than significant.

Trash and Debris. Site design and LID BMPs also possess moderate to high removal effectiveness for trash and debris. Field data indicates high trash and debris removal using bioretention based BMPs identify more than 95% capture/removal of trash from storm water runoff. Based on the implementation these features at project site, impacts from trash and debris for the proposed project are less than significant.



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Dry Weather Flows. Dry weather flows due to anthropogenic sources, such as landscape irrigation water runoff, have the potential to impact local receiving water bodies. Dry weather flows are typically low in course sediment due to the low flow rates but pollutants associated with suspended solids such as phosphorous, trace metals, pesticides are typically found in low concentrations in dry weather flows. The proposed project is not expected to generate significant amounts of dry weather flows due to the drought tolerant landscaping, the use of efficient irrigation systems, the lack of high intensive water use activities on-site, and the use of integrated stormwater landscaping features to collect, hold and treat these flows and eliminate dry flow discharges from project site. Therefore, potential water quality impacts due to dry weather flows would be less than significant.

Groundwater Quality. Infiltration BMPs, such as pervious pavement, require a depth of 10 feet or greater to groundwater to minimize the impacts from storm water pollutants. For sites with shallow groundwater, infiltration BMPs are not recommended unless designed with impermeable liners and subdrains are utilized. For sites with greater than 10 feet depth to groundwater, infiltration BMPs may be utilized on-site for water quality treatment. Based on these design requirements, no pollutants from project runoff are expected to reach groundwater, and groundwater quality impacts are expected to be less than significant.

Based on the incorporation of site design, LID features and BMPs consistent with the UCSB SWMP and Draft Resolution, the proposed project would not result in water quality exceedances and pollutants are not expected in project runoff that would adversely affect beneficial uses. The water quality impacts of the proposed project would be less than significant. 5.6.4 Cumulative Impacts

The design of the San Joaquin Apartments project includes a variety of LID strategies, BMP facilities, and source control measures to provide treatment of stormwater and reduce runoff rates and volumes. With the implementation of the proposed runoff control/treatment strategies, along with proposed and recommended mitigation measures, the proposed project would result in less than significant hydrology and water quality impacts. The San Joaquin Apartments project, as well as other development on the UCSB campus, must comply with regulatory requirements intended to minimize water quality and hydromodification impacts. These regulations include NPDES requirements, General Construction Permit requirements, local storm water management plans, and the RWQCB Joint Effort hydromodification control requirements. In addition, development projects on the UCSB campus are also required to be consistent with the erosion control, habitat protection and water quality policies of the 2010 LRDP. With the implementation of existing regulatory requirements, future hydrology and water quality impacts from development on the UCSB campus, and other development in the watersheds of the Goleta Slough and Devereux Slough, would be minimized to the maximum



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extent possible. Therefore, it is unlikely that future development projects would result in a substantial alteration of drainage systems and watercourses in the project region, or result in significant water quality impacts. The proposed project’s hydrology and water quality impact would not be cumulatively considerable, and the project’s cumulative impacts would be less than significant. 5.6.5 Mitigation Measures and Residual Impacts

Impacts That Can Be Reduced To a Less Than Significant Level Implementation of the following mitigation measure would reduce impacts that may result from the proposed project’s storm drain system to a less than significant level.

HYD-1. The proposed drainage system for the San Joaquin site includes three stormwater

management ponds that would discharge to wetland buffers located on the open space parcel east of and adjacent to the project site. The discharge of collected runoff water from the ponds has the potential to result in local scour and sedimentation impacts.

HYD-1a. Ungrouted rock rip rap energy dissipaters or similar devices shall be

provided at proposed stormwater discharge points. Any construction-related disturbance of wetland buffer that results from the installation of the required energy dissipaters shall be restored at a ratio of 1:1. Restoration activities shall include replanting disturbed areas with native vegetation to minimize the potential for long-term erosion-related impacts. All restoration activities shall be conducted consistent with the requirements of proposed mitigation measure BIO-5b.

Recommended Measures The following measures are recommended to improve the function of the proposed project’s stormwater management system. The implementation of these measures is not required to reduce any project-related impacts to a less than significant level. HYD-2. The low permeability characteristics of soil on the project site may not be

conducive to the use of extensive areas of permeable pavement.

HYD-2a. Site specific soil infiltration tests are recommended to determine the allowable storage reservoir depth and the amount of storm water treatment volume that can be infiltrated into the soil within 48-72 hours in areas where the use of permeable pavement is proposed. If soil infiltration testing determines permeable pavement is not feasible or desirable, the proposed on-site bioretention features would be sufficiently sized to meet the water quality volume requirements.



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HYD-3. The proposed San Joaquin project site stormwater drainage system would not discharge collected runoff water to the southernmost proposed stormwater management pond.

HYD-3a. To ensure that the southerly stormwater management pond is utilized

effectively, it is recommended that the proposed project site storm drain system be modified so that runoff from the southern portion of the San Joaquin site is discharged into the southerly pond.



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5.6 Hydrology and Water Quality - UCSB Hydrology and Water... · Storke Wetlands/Goleta Slough...

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