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Keddy Mill Superfund Site Engineering Evaluation/ Cost Analysis Windham, Maine 17 May 2018

ERM

Engineering Evaluation/ Cost Analysis Report

Keddy Mill Superfund Site Windham, Maine

Prepared by:

Environmental Resources Management One Beacon St.

Fifth Floor Boston, Massachusetts 02108

On behalf of:

ITT LLC 1133 Westchester Avenue White Plains, NY 10604

17 May 2018

DRAFT

Engineering Evaluation/ Cost Analysis Report

Keddy Mill Superfund Site Windham, Maine

17 May 2018

ERM Project No.: 0407067

________________________________________

Lyndsey Coburn, P.G. Project Manager

_________________________________________ John C. Drobinski, P.G., LSP

Partner-in-Charge

__________________________________________

Jason Fernet, P.E., LEP Project Engineer

DRAFT

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Keddy Mill i Engineering Evaluation Cost Analysis Report May 2018

TABLE OF CONTENTS

EXECUTIVE SUMMARY ES-1

1.0 INTRODUCTION 1

2.0 SITE CHARACTERIZATION 3

2.1 SITE DESCRIPTION AND BACKGROUND 3 2.1.1 Site Location and Physical Setting 3 2.1.2 Present and Past Facility Operations 3 2.1.3 Surrounding Land Use and Populations 3 2.1.4 Sensitive Receptors 4

2.2 PREVIOUS INVESTIGATIONS AND CLEANUP ACTIONS 4

2.3 SOURCE, NATURE, AND EXTENT OF CONTAMINATION 5

2.4 ANALYTICAL DATA 6

2.5 STREAMLINED RISK EVALUATION 6 2.5.1 Identification of COPCs 8

3.0 IDENTIFICATION OF REMOVAL ACTION OBJECTIVES 12

3.1 SCOPE OF THE REMOVAL ACTION 12

3.2 REMOVAL ACTION SCHEDULE 13

3.3 COMPLIANCE WITH ARARS AND OTHER CRITERIA 13 3.3.1 Potential Chemical-Specific ARARs 14 3.3.2 Potential Location-Specific ARARs 15 3.3.3 Potential Action-Specific ARARs 15 3.3.4 Removal Action Objectives 15

3.4 CONSISTENCY WITH REMEDIAL ACTIVITIES 15

4.0 IDENTIFICATION AND ANALYSIS OF REMOVAL ACTIONS 17

4.1 IDENTIFICATION OF POTENTIAL REMEDIAL OPTIONS 17 4.1.1 No Action 17 4.1.2 Partial Demolition 17 4.1.3 Complete Demolition 20

Keddy Mill ii Engineering Evaluation Cost Analysis Report May 2018

4.2 ANALYSIS OF REMOVAL ACTIONS 21

5.0 DETAILED ANALYSIS OF ALTERNATIVES 22

5.1 ALTERNATIVE 1 – NO ACTION 23 5.1.1 Effectiveness 23 5.1.2 Implementability 24 5.1.3 Cost 24

5.2 ALTERNATIVES 2 TO 4 - PARTIAL DEMOLITION 24 5.2.1 Effectiveness 24 5.2.2 Implementability 26 5.2.3 Cost 27

6.0 COMPARATIVE ANALYSIS AND RECOMMENDATIONS 29

7.0 REFERENCES 31

LIST OF TABLES

Table 1 Historic Site Ownership and Operations

Table 2 PCB Results from 2015 & 2016 START Sampling

Table 3 Bulk Asbestos Results – March 2016

Table 4 Potential Chemical-Specific Standards

Table 5 Potential Location-Specific Standards

Table 6 Potential Action-Specific Standards

Table 7 Alternative 2 – Opinion of Probable Cost



Table 10 Summary of Comparative Analysis of Removal Actions

Keddy Mill iii Engineering Evaluation Cost Analysis Report May 2018

LIST OF FIGURES

Figure 1 Site Layout

Figure 2 PCB Concentrations (Second Floor)

Figure 3 PCB Concentrations (First Floor)

Figure 4 PCB Concentrations (Basement)

LIST OF APPENDICES

Appendix A Structural Review of Mill Building

Keddy Mill ES-1 Engineering Evaluation Cost Analysis Report May 2018

EXECUTIVE SUMMARY

Environmental Resources Management, Inc. (ERM) has prepared this Engineering Evaluation/Cost Analysis (EE/CA) Report for the Keddy Mill Superfund Site (the “Site”) located in Windham, Maine. This EE/CA is a required part of a proposed non-time critical removal action (NTCRA) being evaluated to expedite a limited cleanup action of contamination in the Mill building materials, at the Keddy Mill National Priority List (NPL) site. NPL Remedial cleanup actions currently underway by the U.S. Environmental Protection Agency (USEPA), such as the remedial investigation/feasibility study (RI/FS), will continue after the proposed NTCRA is completed to address final clean up actions for the remainder of the Site, such as soil and Presumpscot River sediments, as required.

The intent of this report is to summarize the results of prior Site investigations and to evaluate the potential NTCRA for the Keddy Mill building and associated building materials agreed upon as potentially appropriate in the EE/CA Work Plan. These alternatives consisted of no action, partial demolition, and complete demolition. This EE/CA Report was prepared in accordance with the Administrative Settlement Agreement and Order on Consent (AOC, CERCLA Docket No. CERC-01-2017-0049), dated 22 May 2017. Neither the EE/CA Work Plan nor this EE/CA Report address soil, groundwater, sediment, surface water, or any other potentially impacted environmental media.

The Keddy Mill building was extensively sampled by the EPA in 2015 and 2016. Results indicated polychlorinated biphenyls (PCBs) were detected in concrete and wood throughout the Mill building above the Toxic Substances Control Act (TSCA) unrestricted use cleanup standard of 1 mg/kg and the Low Occupancy criteria of 25 mg/kg for porous samples as prescribed under 40 CFR § 761.61(a), and asbestos was detected above the laboratory reporting limit in five of the seven samples collected. A streamlined risk assessment identified field staff workers and trespassers as the most likely human receptors, and consequently the following preliminary Removal Action Objectives (RAOs) were developed:

• Reduce exposure of humans to PCBs potentially related to open building access points;

• Reduce the exposure of humans to physical hazards, and asbestos related to deteriorating Mill building materials; and

• Reduce the threat of release of building contaminants into the river to protect ecological receptors consistent with the long-term cleanup goals.

Through a preliminary analysis of removal action alternatives, both “no action” and “complete demolition” were removed from further screening. The “no action” alternative was not protective of human health or the environment, and

Keddy Mill ES-2 Engineering Evaluation Cost Analysis Report May 2018

the “complete demolition” alternative was infeasible as the below ground portion of the West Wall (which abuts an operable hydroelectric dam) was identified as a critical structure for hydroelectric dam facility stability.

Three partial demolition options were then further reviewed. Each option involved the installation of a retaining wall structure to secure the below ground section of the West Wall while demolishing the remaining building. All options were reviewed in terms of effectiveness, implementability, and cost. Through a thorough comparative analysis, Alternative 2 (Soldier Pile and Concrete Lagging Wall) was identified as the most long-term operational, effective, and implementable, yet cost-effective, alternative.

Keddy Mill 1 Engineering Evaluation Cost Analysis Report May 2018

1.0 INTRODUCTION

The Site was proposed for listing on the National Priorities List (NPL) in 2011. Under the proposed listing, the EPA conducted a Preliminary Assessment/Site Inspection and completed a Final Site Investigation Report in 2011 and 2013, respectively. Keddy Mill was formally listed on the NPL on 12 May 2014.

The Site is currently being evaluated under an Administrative Settlement Agreement and Order on Consent (AOC, CERCLA Docket No. CERC-01-2017- 0049), dated 22 May 2017, for an Engineering Evaluation/Cost Analysis. A NTCRA to address the Mill building contamination would promptly reduce the risk associated with materials on-Site through early action.

This EE/CA Report presents the findings from prior sampling activities conducted on the Mill building and Mill building materialsi in the immediate vicinity of the Site. This report was prepared in conformance with the requirements of the U.S. Environmental Protection Agency (USEPA) “Guidance on Conducting Non-Time Critical Removal Actions Under CERCLA” (USEPA, 1993).

Specifically, the purpose of this NTCRA is to:

Identify chemicals of potential concern (COPCs) through comparison to chemical-specific risk-based concentrations;

Provide an estimate of how and to what extent human receptors might be exposed to these COPCs and their associated human health risks; and

Determine the most beneficial and feasible Mill building materials that can be removed in an expeditious manner in order to immediately reduce risk to potential trespassers and the environment.

Potential Removal Action alternatives were identified and evaluated by applying the EE/CA guidance criteria of implementability, effectiveness, and cost. The identification and screening of the Removal Actions results in an evaluation and a recommendation as to which action would be the most appropriate.

i Mill building materials to include building debris (building materials fallen from the

structure located near the Mill) and the concrete slabs to the north of the Mill building that

reportedly were affected by fire.


The organization structure of this EE/CA Report is outlined below:

Section 2 – describes the physical setting of the Site and the nature and extent of previous investigations. In addition, this section presents summaries of previous investigations/clean up actions, analytical data, and the streamlined risk evaluation.

Section 3 – defines the project scope, goals, and objectives. The applicable or relevant and appropriate requirements (ARARs) and other criteria are identified.

Section 4 – identification and initial screening of potential Removal Action options for the NTCRA.

Section 5 – presents a detailed analysis of potential effectiveness, implementability, and cost of the alternatives.

Section 6 – presents the comparative analyses of the candidate removal actions retained following the screening of potential Removal Actions. A recommendation for implementation is also presented.

Section 7 – presents a list of references used to prepare this document.


2.0 SITE CHARACTERIZATION

2.1 SITE DESCRIPTION AND BACKGROUND

2.1.1 Site Location and Physical Setting

Keddy Mill is a 6.93-acre site located at 7 Depot Street in Windham, Maine. The property itself is located in a mixed commercial/residential area and bounded by Depot Street to the North, a railroad right-of-way to the east, a parking lot to the west, and the Presumpscot River to the south. The Mill is located next to an operating hydroelectric dam and power generating station. A site location map is provided as Figure 1. The Site is currently vacant and consists of a dilapidated, two-story concrete structure (formerly the “Mill”) which includes a basement that was reportedly constructed in the early 1900s. Various other buildings which once existed on site have since been demolished. The Site is now partially enclosed by a locked, chain-link fence.

2.1.2 Present and Past Facility Operations

Between 1756 and 1997, the Keddy Mill property has had over a dozen different owners which used the property for a variety of industrial activities including a sawmill, grist and wool carding mills, wood pulp and box-board manufacturing, steel manufacturing, fabrication of heavy equipment buckets, and a small machine shop. Table 1 provides a list of historic ownership and operations at the property. The facility is currently unoccupied but shows signs of frequent trespassing.

2.1.3 Surrounding Land Use and Populations

As mentioned previously, the property is located in a mixed commercial/residential area. To the south the property is bounded by the Presumpscot River. From review of historical documents and field observations, it appears the river flows under a portion of the western end of the building (where the building has been built on piers with an elevated basement slab). To the west and southwest of the Site there is an operating hydroelectric power plant and an associated parking lot. To the northwest is an apartment complex built in 2006 and owned by the South Windham Housing Corporation. To the north the site is bounded by Depot St. which includes multiple residential and commercial properties. Lastly, to the east is a former Maine Central Railroad right-of-way which is currently owned by Maine Department of Transportation. From field observations, it does not appear that this railroad track is currently operable.


2.1.4 Sensitive Receptors

Human receptors that would most likely contact COPCs are limited to on-Site field staff workers during Site characterization activities and trespassers, both of whom may be exposed to Mill building materials through incidental ingestion, dermal contact, or inhalation of fugitive dusts that may be produced from degraded materials currently present or released during Site characterization activities. No residential impacts are anticipated and, therefore, are not included in this evaluation.

No ecological receptors were evaluated as part of this EE/CA as there are no habitats associated with the Mill and Mill building materials itself (although ecological receptors are located immediately adjacent to the building in the river). However, any response action undertaken at the Site to address acute human health concerns would be expected to also result in beneficial outcomes for the environment. Any removal action taken will be conducted in a manner that will prevent migration of contaminants to ecological receptors (particularly in the river).

2.2 PREVIOUS INVESTIGATIONS AND CLEANUP ACTIONS

The Site has a long history of investigation and cleanup activities which have been summarized below:

1996 - A Phase I and II investigation is conducted by S.W. Cole. Soil samples indicate total petroleum hydrocarbons (TPH) and metals. As a result, eleven tons of petroleum-impacted soil is excavated from the Site.

2003 - Jacques Whitford is contracted to perform a site investigation as part of the initial steps for redevelopment of the Site. Soil samples results indicate diesel range organics (DRO), arsenic, and polychlorinated biphenyls (PCBs.)

July 2005 - A release of PCB-containing oils reportedly from electrical equipment within the Mill is reported to the Maine Department of Environmental Protection (MEDEP). MEDEP contracts Environ to clean up the approximately 30-40 gallons of spilled oil.

October 2005 - Ransom Environmental Consultants is contracted to collect PCBs samples to support a TSCA PCB Self-Implementing Cleanup and Disposal Plan under 40 CFR § 761.61(a). Results indicate PCBs throughout the building, and sludge, dirt, debris, and oily materials that have accumulated in the building are removed. In June 2006, EPA approved a limited Phase I PCB removal project.


May 2010 – GEI Consultants revises and performs the approved Self- Implementing Cleanup Plan. The cleanup includes temporary pea stone capping of exposed soil in the Mill, removal of accessible residual oil from fuel supply piping, and capping of accessible piping.

October 2010 – Summit and MEDEP collect surface soil samples from the exterior of the building. The results are sent as a memorandum to the Town of Windham and indicate PCBs in soil in the range of below laboratory detection limits to 1,100 mg/kg.

April 2011 – Summit collects concrete core samples from the building as well as more soil samples. The concrete cores results indicate PCBs concentrations above >1 mg/kg from each of the three floors of the building, with the highest concentration of 150 ppm in the first floor.

September 2012 – Superfund Technical Assessment and Response Team (START) personnel collect further samples. Soil and slag source samples show concentrations of PCBs and metals.

November 2015 – START personnel collect forty-four (44) concrete floor samples, nineteen (19) concrete wall samples, and four (4) wood boring samples.

March 2016 – START personnel collect forty-six (46) concrete floor samples, twenty-two (22) concrete wall samples, two (2) wood boring samples, four (4) putty/glazing samples, and seven (7) samples from the interior/exterior of the building for asbestos-containing material (ACM) analysis.

2.3 SOURCE, NATURE, AND EXTENT OF CONTAMINATION

As summarized in Table 1, the site has a long history of operations. Past Phase I reports have indicated the presence of PCB-containing electrical components at Keddy Mill, which suggest that electrical capacitors and transformers containing PCBs were used on Site historically. Sampling conducted by the EPA for the Preliminary Assessment/Site Investigation Report (PA/SI, 2016) confirmed PCB contamination was widespread throughout the Mill building on all floors. Due to the age of the building and field observations, the EPA also collected samples of several suspected asbestos-containing materials from the interior and exterior of the building.

The Mill building concrete sampling conducted during the PA/SI indicated no exceedances of volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), or metals above EPA Removal Management Levels for


Industrial Soil. PCBs were detected in concrete and wood throughout the Mill building above the TSCA unrestricted use standard of 1 mg/kg and the Low Occupancy criteria of 25 mg/kg for porous samples. Asbestos was detected above the reporting limit in five of the seven samples collected. These samples have been summarized in Tables 2 and 3 and are depicted on Figures 2-4.

As PCBs and asbestos can pose a threat to the public health, welfare, or the environment, this EE/CA has been developed to identify and evaluate removal alternatives to prevent and mitigate exposure to these hazardous substances.

2.4 ANALYTICAL DATA

Multiple sampling rounds across a variety of media have taken place on Site over the past twenty years. This EE/CA is specifically pertaining to a NTCRA to address the Mill building and Mill building materials in the immediate vicinity at the Site.

The following data from the Preliminary Assessment/Site Investigation Report (2016) was used to develop this EE/CA:

November 2015 – Forty-four (44) concrete floor boring samples (CB-01 through CB-44); nineteen (19) concrete wall boring samples (Wall-01 through Wall-19); and four (4) wood boring samples (WB-01 through WB- 04).

March 2016 – Forty-six (46) concrete floor samples (CB-100 through CB- 136, CB-206 A/B/C, CB-227 A/B/C, and CB-237 A/B/C); twenty-two (22) concrete wall samples (Wall-100 through Wall-121); two wood boring samples (WB-100 and WB-101); four putty/glazing samples (PT-100 through PT-103); and seven bulk asbestos samples (ACM-100 through ACM-104, MC-100, MC-101).

The PCB and ACM analytical results associated with these samples have been summarized in Tables 2 and 3, respectively. The estimated locations of these samples are depicted on Figures 2 through 4.

2.5 STREAMLINED RISK EVALUATION

The streamlined risk evaluation (SRE) is a unique type of risk assessment that EPA developed for use in NTCRA. Consistent with EPA EE/CA guidance (1993), the SRE is intermediate in scope; while it is more detailed than the limited risk evaluation conducted to support emergency removal actions, it is less detailed than a conventional baseline risk assessment typically conducted as part of a


Remedial Investigation (RI)/Feasibility Study (FS). The purpose of a NTCRA is to reduce short-term threats to public health and the environment. Therefore, the primary objective of the SRE within the EE/CA is to justify a removal action and develop appropriate removal action alternatives to reduce risk. This is accomplished through the identification of exposure pathways that represent an immediate and/or acute threat to human receptor populations of concern or the environment.

Accordingly, a SRE has been conducted for the Site to focus on the potential exposures, hazards, and risks posed by the Mill building and Mill building materials (the Mill). As described in the EE/CA Work Plan, this SRE accomplishes the following:

Uses the data provided by the EPA to identify chemicals of potential concern (COPCs) through comparison to chemical-specific risk-based concentrations;

Provides an estimate of how and to what extent human receptors might be exposed to these COPCs; and

Provides an assessment of the human health risks associated with these COPCs.

Existing data provided by EPA is used in this SRE consistent with EPA guidance, including the “Risk Assessment Guidance for Superfund” (USEPA, 1989) and “Framework for Investigating Asbestos-Contaminated Superfund Sites” (EPA, 2008). As described in the work plan, human receptors that would most likely contact COPCs are limited to on-Site field staff workers during the Site characterization activities and trespassers, both of whom may be exposed to Mill building materials through incidental ingestion, dermal contact, or inhalation of fugitive dusts from degraded materials currently present or released during Site characterization activities. No residential impacts are anticipated and, therefore, are not included in this evaluation.

This SRE focuses on the specific response action alternatives for the Mill, which consist of no action, partial demolition, and complete demolition. The SRE is qualitative in nature and does not quantify risk. The focused SRE provides sufficient detail to justify the response action identified for implementation. As stated in the EPA EE/CA guidance (1993), where chemical-specific risk-based concentrations for one or more constituents in a given medium are clearly exceeded, a removal action is generally warranted, and further quantitative assessment that considers all chemicals, their potential additive effects, or additive or multiple exposure pathways is generally not necessary.


As stated previously, there are no ecological habitats associated with the Mill or Mill building materials (although ecological receptors are located immediately adjacent to the building in the river); however, any response action undertaken at the Site to address acute human health concerns would be expected to also result in beneficial outcomes for the environment. Any removal action taken will be conducted in a manner that will prevent migration of contaminants to ecological receptors (particularly in the river).

2.5.1 Identification of COPCs

As described in the EE/CA Work Plan, the first step in the SRE is to identify COPCs. Per the AOC, COPCs are defined as those contaminants present in the Mill and Mill building materials with concentrations in excess of EPA Regional Removal Management Levels (RMLs). RMLs are risk-based screening levels based on the latest toxicity values and exposure assumptions used by EPA’s Superfund program, developed specifically to support removal action decision- making. While they are not necessarily health protective concentrations for chronic exposure, they are useful for identifying potential acute human health concerns.

Representative wood and concrete boring samples were collected from the Mill’s interior walls, floors, and exterior concrete pads by Weston START personnel in November 2015. Putty/glazing samples, samples of ACM, and additional wood and concrete boring samples were collected by Weston START personnel in March 2016. All of the samples were analyzed for PCBs, and select samples were also analyzed for metals, VOCs, SVOCs, and petroleum hydrocarbons. ACM samples underwent bulk asbestos analysis by Polarized Light Microscopy (PLM).

The analytical data from the samples collected by START are presented in the Removal Program Preliminary Assessment (PA)/Site Investigation (SI) Report prepared by Weston for EPA Region 1 (2016). In this report, the data are screened to EPA RMLs, or to other screening levels appropriate for removal action decision-making, including:

1. The MEDEP Cumulative Risk Based Soil Remediation Guideline for petroleum hydrocarbons;

2. The National Emission Standards for Hazardous Air Pollutants (NESHAP) non-friable ACM standard, defined as materials containing >1% asbestos as analyzed by PLM. Although asbestos in ACM at and below 1% may still pose unacceptable health risks depending on site- specific conditions and land use; for the purposes of this SRE, a screening level of >1% asbestos as analyzed by PLM is used to establish asbestos as a COPC.


3. The TSCA criteria for the cleanup and disposal of PCB contamination under 40 CFR § 761 .61(a), which prescribes the procedures for cleanup and disposal of PCB remediation waste, including waste generated as part of cleanup activities (e.g., contaminated environmental media, rags, debris).

Because there are no RMLs for concrete, wood, or putty media, results of these samples are compared to EPA RMLs for industrial soil set to a target hazard quotient (THQ) of 3ii. The relevant findings of the screening evaluation provided in the PA/SI Report (Weston, 2016) are as follows:

VOCs were not detected in any of the concrete samples.

SVOCs and metal results reported for concrete samples did not exceed the EPA RML for industrial soil.

Petroleum hydrocarbons results reported for concrete samples did not exceed MEDEP guidelines for outdoor commercial workers.

PCB results >1 ppm were reported for putty samples. These did not exceed the EPA RML for industrial soil.

PCB results for numerous concrete and wood samples located throughout the building were above the EPA RML for industrial soil and TSCA unrestricted use cleanup standard and the Low Occupancy criteria of 25 mg/kg for porous samples.

Chrysotile (asbestos) was detected at or above the standard of 1% in five of the seven samples collected.

The results presented above, while specific to the samples collected by START in 2015 and 2016, are consistent with site investigations conducted prior to 2015 with respect to PCBs and asbestos. According to the Final Site Assessment Report prepared by H&S/Nobis Environmental JV, LLC (2013), concrete core samples collected by Summit personnel in April 2011 found PCB concentrations at > 1 mg/kg throughout each of the three floors of the building (action levels not specified). An asbestos survey conducted in 2007, provided as Appendix D in the Conceptual Demo Plan (CES, 2016), identified numerous non-friable and

ii Generic RMLs correspond to risk levels of approximately 10-4 (cancer risk) and/or a HQ of 3

(non-cancer hazard). The generic RMLs are generally higher than those selected as final

cleanup levels at sites where a remedial action may be required under Superfund authority.


friable ACM samples collected throughout the Mill that contained asbestos at concentrations greater than 1% as analyzed by PLM.

Based on the results presented above, PCBs and asbestos are the primary COPCs associated with the Mill and Mill building materials. For completeness as part of this SRE, a compilation of the PCB results for samples collected by START in 2015 and 2016 compared to EPA RML and TSCA screening levels is provided in Table 2. ACM results for samples collected by START in 2015 and 2016 are provided in Table 3.

2.5.1.1 Potential Human Receptors and Exposure Pathways

Human receptors that would most likely contact the COPCs are primarily on-Site field staff workers or trespassers, who may be exposed to Mill building materials through incidental ingestion, dermal contact, or inhalation of fugitive dusts from degraded materials currently present or released during Site characterization activities. Even though ACM at the Site exists primarily as large material (i.e., cement board, roofing material, floor tile, etc.) with a low “releasability” of respirable asbestos fibers, as noted by EPA (2008), over time, large non-respirable materials may become broken down by weathering and/or by mechanical forces (e.g., demolition activity), thus increasing the fraction of the material that exists as readily releasable fibers.

The risk-based screening levels are based on EPA industrial risk management levels (RMLs) which assume daily contact with soil over a standard work-year and work- life (i.e., 250 days/year for 25 years). Due to the shorter duration of the anticipated activities that may occur while at the Site, limited exposure to impacted Mill building materials is expected, with exposures that may be experienced by trespassers being far less than that considered within a typical industrial exposure.

Residential impacts are not anticipated and are therefore not included in this evaluation.

2.5.1.2 Potential Risk to Human Health

As stated in the PA/SI Report (Weston, 2016), and discussed previously, the porous building materials found at the Site including concrete, wood, and putty are all contaminated with varying levels of PCBs. The concrete floors are more contaminated than the walls, and the most elevated levels of contamination are found in the western half of the basement. Non-friable and friable ACM samples collected throughout the Mill contain asbestos at concentrations greater than 1% as analyzed by PLM.


Consideration of potentially acute risks that could be posed by exposures to COPC concentrations above risk-based screening levels will provide an immediate benefit to both human health and the environment. Thus, COPC concentrations above risk-based screening levels should be managed under the NTCRA.


3.0 IDENTIFICATION OF REMOVAL ACTION OBJECTIVES

Based on the results of the SRE, the overall goal of the removal action is to reduce exposure and minimize risks posed to human health from asbestos and PCBs in building materials at the Site. Open building access points identified at the Site pose a risk to Site trespassers. In addition, there is a risk of contaminants from the building being released to the environment, particularly to the river. The following preliminary RAOs were developed to reduce the risks to human and ecological receptors at and adjacent to the site:

Reduce exposure of humans to PCBs potentially related to open building access points;

Reduce the exposure of humans to physical hazards, and asbestos related to deteriorating Mill building materials; and

Reduce the threat of release of building contaminants into the river to protect ecological receptors consistent with the long-term cleanup goals.

These objectives will be achieved through attainment of the ARAR-based and risk-based goals. The NTCRA in this EE/CA would remove the primary source materials (i.e., building materials), which contain the highest known concentrations of asbestos and PCBs at the Site. Therefore, the scope of the removal action focuses on the removal of primary source materials.

3.1 SCOPE OF THE REMOVAL ACTION

The scope of the Removal Action will solely focus on the removal of the Mill building and Mill building materials which currently present a potential hazard to human health and the environment in the immediate term.

After the demolition is complete, but prior to demobilization, the site will be stabilized to ensure that:

Contamination from the demolition zone is covered;

Soil and/or contamination cannot migrate from the demolition zone into the river or other environments;

The West Wall maintains its structural integrity and the structural integrity of the adjacent hydroelectric dam; and


Grading at the site does not present a danger to human health.

While some sampling of the West Wall and the soil beneath the Mill may be performed during the NTCRA, the site will be fully characterized and mitigated during remedial activities.

3.2 REMOVAL ACTION SCHEDULE

This EE/CA Report and the Removal Action recommended herein, is subject to regulatory review, public comment, and issuance of an Action Memorandum by USEPA. After the regulatory review and public comment period, the identification of the removal action to be implemented, if any, will be finalized. Given these caveats, the projected schedule for the completion of this Removal Action is as follows:

Construction Document Preparation, Review, and Approval

6 to 12 months

USEPA Review and Approval of PCB Remediation Waste Disposal

2 to 3 months

Preparation of Final Design and Bid Specifications

3 to 4 months

Contractor Procurement 3 months

Implementation of Removal Action, including installation of water, sediment, and erosion controls; stabilization of western foundation wall; and final Site stabilization.

6 to 12 months

The timing of the removal action is dependent upon securing funding to perform the work and obtaining all necessary reviews, approvals, and acceptances from the various regulatory and public entities in a timely manner. The schedule will also be subject to weather and/or other similar unforeseen delays.

3.3 COMPLIANCE WITH ARARS AND OTHER CRITERIA

Section 121(d) of CERCLA requires that on-Site remedial, and to the extent practical removal actions attain or waive ARARs under federal or state environmental laws and regulations and state environmental and facility-siting laws and regulations. ARARs are defined as clean-up standards, standards of control, and other substantive environmental protection requirements, criteria, or limitations promulgated under federal or state law that specifically address a hazardous substance, pollutant, contaminant, remedial action, location, or other


circumstances at a Site. A requirement under environmental laws may either be “applicable” or “relevant and appropriate” to a Removal Action, but not both. Applicable and relevant and appropriate, as defined by the USEPA (1991), are as follows:

Applicable requirements are clean-up standards, standards of control and other substantive requirements, criteria or limitations promulgated under federal environmental or state environmental or facility siting laws that specifically address a hazardous substance, pollutant, contaminant, remedial action, location or other circumstance at a CERCLA site.

Relevant and Appropriate requirements are clean-up standards, standards of control and other substantive requirements, criteria or limitations promulgated under federal environmental or state environmental or facility siting laws that, while not “applicable” to a hazardous substance, pollutant, contaminant, remedial action, location, or other circumstances at a CERCLA site, address problems or situations sufficiently similar to those encountered at the CERCLA site and are well suited to the particular Site.

To Be Considered (TBC) guidance is comprised of non-promulgated advisories or guidance issued by federal or state regulatory bodies that are not legally binding, but may be useful in developing CERCLA remedies; i.e., health effects information or guidance for determining clean-up levels. These ARARs and TBC guidance are divided into three categories: chemical-specific, action-specific, and location-specific requirements.

This section describes the ARARs and TBC guidance that may be applied to the removal action being evaluated within this EE/CA Report. In accordance with the National Contingency Plan (NCP) [40 CFR 300.415(j)], removal actions must comply with ARARs only “to the extent practicable considering the exigencies of the situation.”

3.3.1 Potential Chemical-Specific ARARs

Chemical-specific requirements establish health- or risk-based concentration limits or ranges for specific hazardous substances in various environmental media. These ARARs provide site clean-up levels or a basis for calculating cleanup levels for chemicals of concern. Chemical-specific ARARs are also used to indicate an acceptable level of discharge, to determine treatment and disposal requirements for a particular remedial activity, and to assess the effectiveness of a remedial alternative. The chemical-specific ARARs and TBC guidance identified for a Removal Action identified herein for the Site are presented in Table 4.


3.3.2 Potential Location-Specific ARARs

Location-specific requirements establish restrictions on the types of remedial activities that can be performed based on specific Site characteristics or location. Location-specific ARARs provide a basis for assessing restrictions during the formulation and evaluation of Site-specific remedies. Remedial alternatives may be restricted or precluded based on standards, such as siting laws for hazardous waste facilities or based on proximity to wetlands, floodplains, or man-made features such as historic buildings or archeological sites. The location-specific ARARs and TBC guidance identified for a Removal Action for the Site are presented in Table 5.

3.3.3 Potential Action-Specific ARARs

Action-specific requirements establish controls or restrictions on the design, implementation, and performance of removal actions. These ARARs specify performance levels, actions, or options, and specific levels for the discharge of residual chemicals. They also provide a basis for assessing the feasibility and effectiveness of the remedial alternatives. The action-specific ARARs and TBC guidance identified for a removal for the Site are presented in Table 6.

3.3.4 Removal Action Objectives

The goals of the Removal Action are to effectively reduce the potential for exposures to an acceptable range, to mitigate impacts in a manner that improves protection of human health and the environment, and to achieve compliance with established ARARs to the maximum extent practicable. More specifically, the RAOs for this NTCRA include the following:

Reduce exposure of humans to asbestos fibers potentially released from building materials;

Reduce the exposure of humans to physical hazards, PCBs, and asbestos related to open building access points; and

Reduce the threat of release of building contaminants into the river to protect ecological receptors consistent with the long-term cleanup goals.

3.4 CONSISTENCY WITH REMEDIAL ACTIVITIES

The NTCRA, to the extent practicable, will contribute to the efficient performance of the long-term remedial action. The NTCRA will remove the Mill and associated material which will then not interfere with the remedial investigation and any future remedial action that may be required. It will assist the remedial investigation by providing access to the soil and river sediments beneath the building which is not currently accessible due to the dilapidated


condition of the building. In addition, procedures will be put in place to prevent the spread of contamination from the demolition zone.

A temporary coffer dam will be constructed (shown in Figure 1) to prevent building materials entering the river during demolition;

Mitigation measures (e.g. wetting) will be used to control dust during all removal activities;

Waste water generated from the removal action will be treated and disposed of on-site or off-site at a licensed facility;

The West Wall will be stabilized and sealed so that it:

o maintains the structural integrity of the West Wall;

o maintains the structural integrity of the adjacent hydroelectric dam; and

o minimizes the release of potential contamination on the West Wall; and

Shoreline stabilization measures will be used to prevent soil, etc. entering the river after the demolition is completed.


4.0 IDENTIFICATION AND ANALYSIS OF REMOVAL ACTIONS

This section presents the identification and initial screening of potential Removal Action options for the NTCRA. Section 5.0 provides a comprehensive analysis of the resulting alternatives.

4.1 IDENTIFICATION OF POTENTIAL REMEDIAL OPTIONS

The early action Removal Action options that meet the RAOs and are further assessed herein are presented below:

No action;

Partial Demolition; and,

Complete Demolition.

In the case of partial demolition, several sub-alternatives are available to accomplish this overall task, including several options to stabilize the West Wall (See Figure 1). Each of these options is discussed subsequently in this section.

4.1.1 No Action

CERCLA and the NCP require that the no-action alternative be evaluated at every site to establish a baseline for comparison. Under this alternative, no Removal Action of any kind would be employed. The no-action alternative will not reduce any risk associated with direct contact, ingestion, or inhalation of impacted materials or releases to the environment; therefore, this alternative is not more protective of human health and the environment than the current condition.

Even though the no-action alternative does not meet the RAOs, it is retained as an alternative to serve as a basis for the comparison of performance of other alternatives.

4.1.2 Partial Demolition

Partial demolition would mitigate the risk to human health and the environment through demolition and off-site disposal of the building; however, the West Wall of the current Mill building would remain in place to maintain the stability of the river and the abutting hydroelectric dam facility structure. This option will include reviewing treatment and/or disposal of waste generated by demolition.


A structural engineering survey was conducted on 2 October 2017 by Alfred Benesch & Company (Benesch) to assess the stability of site structures, specifically as they relate to the Presumpscot River and the hydroelectric dam. It was determined by Benesch (see Appendix A) that the, “West Wall of the current Mill building is the critical element for maintaining stability at the site upon demolition of the existing Mill building.” This is mainly owning to the fact that demolition would include the removal of the basement and first floor slabs, which appear to act as struts that laterally support the existing brick West wall. Furthermore, the West wall currently exhibits areas which are visibly buckling (Appendix C [Photo Log] to Appendix A). Therefore, demolition options presented below incorporate stabilization of the West Wall. In all partial demolition alternatives, geotechnical exploration will need to be conducted prior to temporary stabilization to further understand the subsurface conditions and parameters to effectively design the stabilization technique as well as to ensure the safety of the workers conducting the construction. It is possible that the geotechnical investigation may provide information which would change the selected remedy. Nonetheless, it is anticipated that partial demolition would be implemented using the following steps:

Temporary Stabilization of the West Wall – Soil nailing with temporary shotcrete facing would be installed to secure the wall during demolition activities. This is the most attractive temporary stabilization solution as it can be performed with limited access conditions.

Installation of Portable Cofferdam – An L-shaped portable coffer dam would be installed against the south end of the West Wall and along the stream. This dam would temporarily divert flow and prevent water from entering the demolition and construction area. This will protect the river from adverse impacts during demolition of the Mill, so the river ecosystem and downstream recreation areas are not impacted. If water is still flowing through the former sawmill penstocks and out the aqueducts under the West Wall, the inlets would be plugged to prevent the water flow into the demolition zone.

Demolition of the Mill – The basement slab and entire building with the exception of the West Wall below ground level would be demolished. Demolition would begin on the second floor and move down to the basement slab. Future structural analysis may determine that a small portion of the slab immediately adjacent to the West Wall would need to remain in place for stabilization. Mitigation measures (e.g. wetting) will be used to control dust that may contain site contaminants. Waste water generated from the removal action will be treated and disposed of on-site or off-site at a licensed facility. The bank along the Presumpscot River would be protected with erosion control measures such as silt fencing


and a super-silt fence to prevent erosion into the river during demolition and construction activities.

Installation of a Retaining Wall – One of the three retaining wall alternatives presented in the structural engineering survey would be constructed as a permanent measure to stabilize the deteriorating West Wall. This step would not be necessary if the soil-nail wall alternative is chosen.

Site Restoration and Stabilization of the River Bank – Riverbank restoration and stabilization will be done in accordance with the requirement of the ARARs, to the extent practicable. Native plant species with erosion control mats would be planted at higher elevations for further slope stability. Note that any restoration or stabilization measures taken may only be temporary depending on whether additional Site alteration may be required under any future remedial action for the Site.

4.1.2.1 Retaining Wall Options

The three retaining wall options presented in the structural engineering survey report (Appendix A) are described below:

Alternative 2 - Soldier Pile and Concrete Lagging Wall

The Soldier Pile and Concrete Lagging Wall would consist of drilling soldier beams into bedrock below the river (assumed to be six to twelve feet below the building floor based on documentation and observations) at regular intervals along the wall. Lagging consisting of concrete panels would then be placed behind the front pile flanges and backfilled. The lagging acts to retain soil across the piles and transfers the lateral load to the soldier pile system.

It is anticipated that the soldier pile would be installed through the river bed. The slab between the existing West Wall and the beams would be reinforced to allow the lagging wall construction to begin at the current slab elevation. This would enable the river to continue flowing through the culverts and under the lagging wall.

Alternative 3 - Soil Nail Wall with Permanent Shotcrete Facing

A soil nail wall would involve the insertion of horizontal reinforcing elements (usually rebar) through pre-drilled holes into the existing failing wall and fill materials behind the wall. The nails would then be grouted in place. These “nails” would act to reinforce the existing West Wall by resisting lateral earth pressure. The wall would then be finished with a permanent shotcrete facing wall to help prevent the soil between the soil nails from becoming unstable. The


alternative would use more robust and permanent soil nails than what is proposed for temporary stabilization measures.

Alternative 4 - Reinforced Concrete Cantilever Wall

A reinforced concrete cantilever wall with a large toe could be installed to retain the West Wall. Small “doors” would be cut through the bottom of the wall that is perpendicular to the riverbed to allow the river to flow through where the culverts currently exist.

4.1.2.2 Off-site Material Disposal

Although alternatives exist for possible on-site treatment of PCB- contaminated building materials, it was determined that the most feasible and cost- effective option would be off-site material disposal. Building material waste will be disposed of off-site in containers meeting the requirements of the DOT Hazardous Materials Regulations (HMR) at 49 CFR parts 171 through 180 to an authorized PCB disposal facility.

The PCB-contaminated building material will be classified as PCB remediation waste as defined in 40 CFR § 761.3. The PCB remediation waste will be subdivided into two classifications less than (<) 50 mg/kg and greater than or equal to (≥) 50 mg/kg for disposal purposes. PCB remediation waste ≥ 50 ppm will be disposed of in a hazardous waste landfill or a PCB disposal facility, per 40 CFR §761.61(a)(5)(i)(B)(2)(iii). PCB remediation waste < 50 ppm will be disposed of in a municipal waste landfill or as otherwise allowed under 40 CFR §761.61(a)(5)(i)(B)(2)(ii). These disposal options are contingent upon EPA approval in accordance with 40 CFR § 761.61.

Removal and disposal of asbestos will be conducted by a licensed asbestos contractor in accordance with ARARs. Potential landfills have been identified for disposal of ACMs. However, if the ACM is also contaminated with PCBs, a disposal facility will need to be identified that can accept both PCBs and asbestos waste.

4.1.3 Complete Demolition

Complete demolition would mitigate the risk to human health and the environment through a complete demolition of the entire Mill, including the West Wall. Stability of the river and hydroelectric dam facility would be maintained through engineering the shoreline, which would include installing appropriate erosion control/stabilization measures and cover materials. This option would also include the review of treatment and/or disposal of waste generated by the demolition. This option is not preferred since the West Wall of


the current Mill building has been identified by the hydroelectric facility operator as a critical structure for maintaining stability of the facility.

Further uncertainty is introduced for this option due to the presence of aqueducts at the base of the West Wall through which water is flowing. Historical references indicate that the open area immediately west of the West Wall was previously occupied by a former sawmill which was powered by river water flowing through subsurface penstocks. These penstocks may still exist beneath this area. During the investigation phase of the NTCRA, inlets containing flowing water were observed up-river of the hydroelectric dam.

The potential for contamination to be present on and behind the West Wall will be addressed either during the Pre-Design work for the NTCRA or during the on-going RI/FS.

4.2 ANALYSIS OF REMOVAL ACTIONS

As stated above, although the no-action alternative does not meet the RAOs it has been retained as an alternative in the detailed analysis to serve as a basis for the comparison of performance of other alternatives. All three partial demolition options have also been included for further analysis as all options have the potential to meet the RAOs and have been assessed as generally feasible to construct on Site.

Although complete demolition would be theoretically feasible and would meet the RAOs, it has been removed from further consideration as the West Wall has been identified as a critical structural element. The mass of soil behind the wall abuts the hydroelectric plant and the adjacent hydroelectric dam impoundment, and it is therefore vital to maintaining the stability of these structures. Removal of this wall would be theoretically possible but the cost would be orders of magnitude greater than partial demolition options. Furthermore, all three partial demolition options include reinforcing structures that would create a barrier between the old West Wall and possible sensitive receptors thus eliminating potential short-term exposure to human or ecological receptors, until any remaining risks can be addressed by the remedial action. As all partial demolition options are both significantly more feasible and cost-effective, complete demolition has been eliminated from further analysis.


5.0 DETAILED ANALYSIS OF ALTERNATIVES

This section of the EE/CA report formulates alternatives compiled from the Removal Action options that have been retained through the screening process discussed in Sections 4.1 and 4.2. Each of the resulting alternatives is considered potentially applicable for the NTCRA, and consists of elements of the various options as needed to address each risk consideration. The following Removal Action alternatives were configured for more comprehensive evaluation:

Alternative 1 – No Action; and

Partial Demolition

o Alternative 2 - Soldier Pile and Concrete Lagging Wall

o Alternative 3 - Soil Nail Wall with Permanent Shotcrete Facing

o Alternative 4 - Reinforced Concrete Cantilever Wall

Each of these Removal Action alternatives are further discussed and evaluated independently against the specific screening criteria below. Opinions of Probable Construction Cost for each of the alternatives were developed for incorporation into the comparative analysis, and are presented in Tables 7 through 9.

The removal action alternatives were evaluated against three screening criteria, as follows:

Effectiveness;

Implementability; and,

Cost.

The effectiveness criterion addresses the ability of an alternative to meet the RAOs, including overall protection of human health and the environment, attainment of ARARs and risk-based standards developed using TBC guidance, long-term effectiveness and permanence, short-term effectiveness, and reduction of toxicity, mobility, or volume by treatment. The protection of human health and the environment considers the reduction, control, or elimination of risks at the Site through the use of engineering or institutional controls.

Attainment of ARARs and risk-based standards developed using TBC guidance considers the ability of Removal Actions to meet statutory and regulatory


requirements. Long-term effectiveness and permanence includes consideration of the magnitude of risks associated with residuals or untreated waste at the Site relative to trespassers and the reliability of the removal action to maintain its integrity. Short-term effectiveness includes the consideration of community protection from air quality impacts, fugitive dust, and the transportation of hazardous materials; worker protection during implementation; environmental impacts; and the timeframe required to achieve protection. Reduction of toxicity, mobility, or volume through treatment includes the consideration of CERCLA’s preference for treatment and the extent and irreversibility of treatment.

The implementability criterion addresses the technical and administrative feasibility of implementing an alternative, and the availability of various materials and services required during its implementation. Technical feasibility includes the consideration of the long-term reliability, prior application, and operational difficulties of an alternative as well as logistical, climate, and terrain limitations. Administrative feasibility includes the consideration of coordinating activities with regulatory agencies and obtaining easements, right-of-way agreements and approval of disposal sites. The availability of materials and services includes consideration of the availability and distance to off-Site materials suppliers and/or treatment, storage, and disposal facilities.

The cost criterion addresses the relative magnitude of capital costs. Capital costs consist of direct and indirect costs. Direct costs include costs associated with construction, equipment, materials, transportation, disposal, analytical services, treatment, and operation. Indirect costs include expenses related to engineering, design, legal fees, permits, and start-up.

In addition, the potential for acceptance of an alternative by the state and the community is also considered in the implementation of a Removal Action.

5.1 ALTERNATIVE 1 – NO ACTION

No active response action would be implemented under this alternative. This alternative is not being proposed, but the “No Action” alternative must be evaluated at every site to establish a baseline for comparison.

5.1.1 Effectiveness

The No Action alternative does not protect public health or the environment. This option is not in compliance with ARARs. As the building materials have been identified as contaminated, this option is not viable for long-term effectiveness, short-term effectiveness, or reduction of toxicity/mobility/volume through treatment.


5.1.2 Implementability

Since there are no active construction activities or engineering/administrative issues with this alternative, the no action alternative is readily implementable. However, State and Community acceptance of this alternative is unlikely.

5.1.3 Cost

There are no costs associated with this alternative.

5.2 ALTERNATIVES 2 TO 4 - PARTIAL DEMOLITION

5.2.1 Effectiveness

5.2.1.1 Overall Protection of Public Health and the Environment

All three partial demolition alternatives (Alternatives 2, 3, and 4) would involve the full demolition of the Mill building, excluding the existing West Wall below ground level due to stability issues. Although the West Wall would remain on-site, the installation of any one of the three wall stabilization designs would cover the potential contamination and thus minimize potential releases and exposure to human or ecological receptors. If contamination is present on the wall or in the soil behind, it will be addressed either during Pre-Design work for the NTCRA or during the remedial measures. The removal of the majority of the Mill building would greatly increase the overall protection to human health and the environment as the potential source of PCB and ACM contamination would be removed from the Site.

5.2.1.2 Compliance with ARARs and Other Criteria, Advisories, and Guidance

All partial demolition options would be implemented to comply with ARARs and with risk-based standards derived from TBC guidance identified in Tables 4-6 to the maximum extent possible.

As required under the federal Clean Water Act, EPA made a draft determination that partial demolition is the Least Environmentally Damaging Practicable Alternative (LEDPA) to protect federal jurisdictional wetland and aquatic habitats on the site because (a) there is no practical alternative method that will achieve cleanup objectives with less adverse impact on federal jurisdictional wetlands and (b) all practical measures will be taken to minimize and mitigate any adverse impacts to federal jurisdictional wetlands and aquatic habitats from the work, to the extent practicable. All work within the 500-year floodplain of the river will be conducted so as to not impair floodplain resources or cause a


significant loss of flood storage capacity within the waterway to the extent practicable.

No major issues with ARARs compliance have been identified at this time.

5.2.1.3 Long-term Effectiveness and Permanence

Partial demolition is an effective long-term alternative as it removes the primary source (the building and building materials), that currently represent a risk to human health and the environment, as discussed in Section 2.5.

According to the “Conceptual Demolition Work Plan” conducted by CES Inc. in March 2016, it was estimated that approximately 5,200 yd3 of concrete exists on Site along with an estimated 102 yd3 of recyclable steel. Although the West Wall would remain on site for all partial demolition options, as a conservative measure it has been assumed these estimates cover the entire amount of building materials which will be shipped off-site as PCB-contaminated waste. Furthermore, the asbestos identification survey (CES, 2016) also identified more than 43,000 ft2 of ACM on Site.

Partial demolition would provide an irreversible, permanent means of removal as most hazardous building material would be shipped off-site.

The installation of any one of the three wall stabilization designs would maintain the structural integrity of the West Wall and thus minimize releases of potential contamination on the wall and exposure to human or ecological receptors. Stabilization of the dilapidated wall will also address the safety issue posed should the wall collapse. The construction of the stabilization options would result in some risk due to the construction constraints; however, a carefully engineered construction plan will mitigate much of the construction-period risk. All three wall stabilization alternatives would provide a reliable, long-term solutions. However, Alternative 3 (permanent soil nail wall with shotcrete facing) is highly contingent on soil type and groundwater can negatively impact stability. These issues may contribute to a less effective long-term solution than the other partial demolition alternatives.

5.2.1.4 Reduction of Toxicity, Mobility, or Volume through Treatment

None of the proposed alternatives include treatment, except to the extent any water generated from the removal work requires treatment before discharge.

5.2.1.5 Short-Term Effectiveness

Although partial demolition provides the greatest long-term effectiveness, extreme care will need to be taken during demolition and construction activities


to provide the best protection to human and environmental sensitive receptors. Appropriate erosion control measures will be installed prior to any site activities including (but not limited to) silt fence, super silt fence, straw waddles, and erosion control blankets along the river bank. The placement of a cofferdam will provide protection to the river and river bank from loose building materials falling below into the river. Additionally, air monitoring and dust control will be conducted during demolition activities to provide protection to on-site workers as well as the surrounding community from asbestos and other site contaminants.

5.2.2 Implementability

5.2.2.1 Technical Feasibility

All partial demolition alternatives have been identified as currently feasible. As stated above, geotechnical explorations will need to be conducted prior to temporary stabilization to ensure the safety of the workers conducting the construction as well as the viability of stabilization. It is possible that these geotechnical surveys may provide information which would change the chosen alternative. However, it is not possible to currently predict these issues without further intrusive work. These alternatives are also feasible if the subsurface penstocks that powered the former sawmill are still in place with river water flowing through them, although the presence of flowing water under the building will present additional implementability challenges.

5.2.2.2 Administrative Feasibility

All partial demolition options are administratively feasible. As the demolition and retaining wall stabilization would take place above and along the Presumpscot River, it is anticipated a large amount of coordination would be needed across multiple agencies. Work will be carefully coordinated with the EPA and MEDEP to follow TSCA regulations as well as the Maine Natural Resources Protection Act and other ARAR requirements.

5.2.2.3 Availability of Services and Materials

The following presents a table of services and materials that would be necessary for partial demolition. No issues have been identified with regards to their availability.


Services Materials

General contractor – Construction and

Demolition Coffer Dam

Licensed Asbestos Contractor – For removal of

ACM material on Site Building materials for retaining wall

Hazardous Waste Transporter – For

transporting of PCB contaminated material to

an appropriate landfill

Landfills – Potential landfills have been

identified for waste with ≥ 50 ppm PCB

impacts, < 50 ppm PCB impacts, and ACM

material

5.2.2.4 State and Community Acceptance

A Notice will be placed in the local newspaper inviting the public to comment on this EE/CA during a 30-day public comment period.

Federal ARARs require EPA to specifically solicit public comment concerning potential impacts to federal jurisdictional wetlands and floodplain from the proposed river diversion and building demolition. In addition, EPA is soliciting public comment on its draft determination that partial demolition is the Least Environmentally Damaging Practicable Alternative for addressing site contamination while minimizing harm to wetland and aquatic habitats.

The State has also reviewed this EE/CA and provided comments on the document. They may submit additional comments during the Public Comment period.

The comments received will be addressed in a Responsiveness Summary in which EPA’s written responses to the comments will be documented. EPA’s Action Memorandum will take into account the comments received and will include the Responsiveness Summary as an attachment.

5.2.3 Cost

The direct/indirect costs for each of the three alternatives are summarized in Tables 7 through 9.

5.2.3.1 Direct & Indirect Capital Costs

Direct and indirect capital costs have been summarized for each partial demolition option in Tables 7 through 9.


5.2.3.2 Long-Term Operation and Maintenance Costs

Annual visual inspections of the retaining wall supporting the West Wall would be conducted to confirm continued stability. All options are expected to have a lifespan of at least 50 years.

Annual O&M would consist of visual inspections and potential future structural assessments that may be required, which will be addressed as part of the remedial action.


6.0 COMPARATIVE ANALYSIS AND RECOMMENDATIONS

Each of the partial demolition alternatives were evaluated in Section 5.2. A comparative analysis of the alternatives relative to each other is described within this section to determine the respective advantages and disadvantages of each and to determine the most suitable action for implementation. The screening criteria utilized for individual alternative evaluation (including implementability, effectiveness, and cost) were also applied in this comparative analysis. The Summary of Comparative Analysis of Removal Actions is presented in Table 10.

In order to objectively compare the Removal Action alternatives, a weighted array was developed applying numerical weights and ratings to each of the screening criteria. Implementability and effectiveness were further subdivided for consideration of the specific components of those criteria. An appropriate relative weight for each component was assigned, from 0.5 to 1.5, for these subcategories; the relative weights are indicative of the significance of the contribution of that component to the overall criterion. Ratings between 1 (lowest) and 5 (highest) were assigned based upon a subjective evaluation of the degree to which each component satisfied the established goals. As noted in Table 10, the overall scores range from 54 to 66.75. This overall score is based on subjective input inherent in the process; nevertheless, the higher scores are indicative of anticipated overall performance of a particular remedy with respect to the other alternatives when considering the screening criteria and, therefore, assist in the decision-making process in conjunction with other evaluations.

The preferred Removal Action alternative should provide the optimum balance among the alternatives with respect to the screening criteria. Specifically, the preferred alternative must satisfy the RAOs, comply with ARARs, and be cost effective. Consequently, Alternative 2 – Soldier Pile and Concrete Lagging Wall is recommended as the preferred Removal Action alternative. Alternative 2 is consistent with the RAOs and had the highest overall score relative to the other alternatives when applying the screening criteria. The cost associated with this alternative is within the range of the other alternatives. Although Alternative 3 was the least expensive, this option is highly dependent on having the correct soil geology which is currently unknown. Further investigation may result in a more favorable rating for this option.

The other key factors that support this recommendation include the following:

The reduction of risk to human health through the removal of PCB contaminated building materials and ACM;

Leaving the Site in a condition that will not interfere with any future remedial actions that may be required;

The ability to structurally stabilize the West Wall so that it;


o does not pose a risk of collapse into the river or threaten to release contaminants that will pose a risk to human or ecological receptors; and

o Maintains the structural integrity of the adjacent hydroelectric dam.

The ability to reduce risk at a moderate cost in comparison to Alternative 3.


7.0 REFERENCES

CES, Inc., 2016. Summary Report, Conceptual Demolition Work Plan, Keddy Mill, 7 Depot Street, Windham, Maine. March 22, 2016.

United States Environmental Protection Agency (USEPA), 1989. Risk Assessment Guidance for Superfund. EPA 540-R-02-002.

United States Environmental Protection Agency (USEPA), 1993. Guidance on Conducting Non-Time Critical Removal Actions Under CERCLA. EPA540-R-93-057. Publication 9360.0-32. August.

United States Environmental Protection Agency (USEPA), 2008. Framework for Investigating Asbestos-Contaminated Superfund Sites. Prepared by the Asbestos Committee of the Technical Review Workgroup of the OSWER. OSWER Directive #9200.0-68. September.

Weston Solutions, Inc., 2016. Removal Program Preliminary Assessment (PA)/Site Investigation (SI) Report for the Keddy Mill Site, Windham, Cumberland County, Maine. 16 November through 19 November 2015 and 28 March through 31 March. Submitted By: Weston Solutions, Inc. Region I Superfund Technical Assessment and Response Team (START).

H&S/Nobis Environmental JV, LLC. 2013. Final Site Inspection Report for the Keddy Mill Site, Windham, Maine. January 2013.

Tables

Table 1Historic Site Ownership and Operations a

Keddy Mill Superfund SiteWindham, Maine

Prior to 1756 - unknown William Knight Sawmill

Unknown - 1847 Unknown Grist mill and wood carding mills

1844 - 1865 Casco Manufacturing Company

Sawmill (disassembled and relocated in approximately 1853) and cotton mill (burned down in 1856)

1865-1875 Various Owners Unoccupied

1875-1900 Charles A. Brown Company

- Wood pulp and box-board manufacture-Constructed large mill complex on the Site

1900 - March 1940 Androscoggin Pulp Company

- Wood pulp and box-board manufacture-Enlarged the mill complex on the Site with the construction of several

new buildings

March 1940 - July 1945 Cumberland Securities Group

Operations at this time are not known, but are assumed to be wood pulp and box-board manufacture

July 1945 - December 1945 Windham Fibers 1944 Fire Insurance map indicates that the facility was still used to manufacture box board

December 1945 - August 1953 Maine Steel Steel manufacture and fabrication of heavy equipment buckets

August 1953 - December 1953 Weiland, Hoodin, Buthckes, Jelin Unknown

December 1953 - August 1954 Irving Fox Unknown

August 1954 - June 1961 Atlantic Mills, Inc. Unknown

June 1961 - November 1969 Keddy Mfg Co Unknown

November 1969 - August 1973 Grinnell Corporation Fire suppression materials manufacture

August 1973 - May 1974 Park Corporation Liquidation of heavy machinery within the former mill complex

May 1974 - July 1975 Lawrence J. Keddy

Operations not known. Until this time period, the former mill property included much of the property located south of the mill. The southern portion of the property was conveyed to S.D. Warren in October 1974,

and was no longer part of the Keddy Mill property.

July 1975 - January 1978 National Metal Converters Operated by National Metal Converters (also known as New England Steel Company). Metals recycling.

January 1978 - April 1993 Lawrence J. Keddy Unknown; Presumed steel manufacture

April 1993 - November 1997 Barnard-Marquit Corp. Unknown. In November 1997, the Site was used as a small machine shop and equipment storage.

November 1997 - September 2002 Presumpscot/ Phoenix Corp. Unknown

September 2002 - November 2006 Lumas, Inc. Unknown

November 2006 - October 2011 HRC-Village at Little Falls, LLC Site redevelopment

October 2011 - date of report Keddy Mill Enterprises, LLC Site redevelopment

Notes:

Approximate Years Of Operation Owner Operation & Events of Significance

a. USEPA, 2013. Final Site Inspection Report for Keddy Mill Windham, Maine

ERM Page 1 of 1 Keddy Mill 11/27/2017

stacey.harvey

Rectangle

Table 2PCB Results from 2015 and 2016 START Sampling Keddy Mill Superfund SiteWindham, Maine

Location ID CB-01 CB-02 CB-03 CB-04 CB-05 CB-06 CB-07 CB-08 CB-09 CB-10 CB-11 CB-12 CB-13 CB-14 CB-15 CB-16 CB-17 CB-18 CB-19 Sample Date Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15Sample Type Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor

Depth 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in.

Analyte Unit

TSCA-High Occupancy

Criteria9:

TSCA-Low Occupancy Criteria10:

EPA RML11

(Industrial Soil):

Aroclor-1242 mg/kg NS NS 95 19 3.3 ND ND ND ND ND ND ND ND ND ND ND 6.3 ND ND ND 4.7 0.2Aroclor-1254 mg/kg NS NS 44 15 17 0.17 35 36 56 38 9.9 6.9 140 5.4 5.4 8.8 10 19 15 0.7 1.6 0.31Aroclor-1260 mg/kg NS NS 99 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND NDAroclor-1262 mg/kg NS NS NS NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NRAroclor-1268 mg/kg NS NS NS ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

Total Aroclors mg/kg 1 25 NS 34 20.3 0.17 35 36 56 38 9.9 6.9 140 5.4 5.4 8.8 16.3 19 15 0.7 6.3 0.51

Notes:1. Bold and gray cells above EPA RMLs2. Yellow highlighted cells above TSCA-High Occupancy Criteria3. Yellow highlighted cells with red text above TSCA-Low Occupancy Criteria4. NS = No Standard5. mg/kg = milligrams per kilogram6. ND = Not Detected7. NR = Not Reported8. BRL = Compound detected below the reporting limit.9. TSCA High = 40 CFR 761.61 High Occupancy contamination levels for porous surfaces.10. TSCA Low = 40 CFR 761.61 Low Occupancy contamination level for porous surfaces.

Source: Weston Solutions, Inc., 2016

11. Regional Removal Management Level (RML) Summary Table (TR=1E-4, HQ=3) July 2017; Provided for comparison purposes only

- -


Location IDSample DateSample Type

Depth

Analyte Unit

TSCA-High Occupancy

Criteria9:


EPA RML11

(Industrial Soil):

Aroclor-1242 mg/kg NS NS 95Aroclor-1254 mg/kg NS NS 44Aroclor-1260 mg/kg NS NS 99Aroclor-1262 mg/kg NS NS NSAroclor-1268 mg/kg NS NS NS

Total Aroclors mg/kg 1 25 NS




CB-20 CB-21 CB-22 CB-23 CB-24 CB-25 CB-26 CB-27 CB-28 CB-29 CB-30 CB-31 CB-32 CB-33 CB-34 CB-35 CB-36 CB-37 CB-38 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in.

6.1 ND 120 7.3 ND 15 24,000 ND ND ND ND 0.55 ND BRL ND ND ND ND ND1.7 ND 20 8.7 30 7.4 ND 13,000 27 4.6 5.7 1.1 0.51 1.2 0.63 1.1 0.42 1.7 18ND ND 12 ND ND ND ND ND 3.4 ND ND ND ND ND ND ND 0.27 3.7 9.1NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NR NRND ND N ND ND ND ND ND ND ND ND ND ND 0.54 ND 0.98 ND ND ND7.8 ND 152 16 30 22.4 24,000 13,000 30.4 4.6 5.7 1.7 0.51 1.7 0.63 2.1 0.69 5.4 27.1

- - ----, .-----------,



Depth

Analyte Unit

TSCA-High Occupancy

Criteria9:


EPA RML11

(Industrial Soil):






CB-39 CB-40 CB-41 CB-42 CB-43 CB-44 CB-100 CB-101 CB-102 CB-103 CB-104 CB-105 CB-106 CB-107 CB-108 CB-109 CB-110 CB-111 CB-112 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in.

ND ND ND ND ND ND 0.18 1.3 29 5.1 6.7 21 0.8 ND 5.5 ND 17 0.19 ND14 33 ND 18 15 ND 0.98 3.4 18 24 13 20 1.4 37 42 46 9.7 1.8 4.14.8 ND ND ND ND 0.18 ND ND ND ND 7.8 7.6 ND 7 13 ND ND 0.45 2.8NR NR NR NR NR NR ND ND ND ND ND ND ND ND ND ND ND ND NDND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND18.8 33 ND 18 15 0.18 1.16 4.7 47 29.1 27.5 48.6 2.2 44 60.5 46 26.7 2.44 6.9

-



Depth

Analyte Unit

TSCA-High Occupancy

Criteria9:


EPA RML11

(Industrial Soil):






CB-113 CB-114 CB-115 CB-116 CB-117 CB-117 CB-118 CB-119 CB-120 CB-121 CB-122 CB-123 CB-124 CB-125 CB-126 CB-127 CB-128 CB-129 CB-130Mar-16 Mar-16 Mar-16 Mar-16 Nov-15 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-3 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in.

ND 0.25 ND 2.1 1.2 30 12 2.1 1.7 ND ND ND ND 22 ND ND ND ND 1.133 0.54 2,800 1.3 0.53 16 5.9 3.3 2.3 250 88 120 29 35 13 21 7.7 2.5 2.3ND ND ND ND ND ND ND ND ND ND ND 33 10 ND ND 16 7.5 1.1 NDND ND ND ND NR ND ND ND ND ND ND ND ND ND ND ND ND ND 1.8ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND33 0.79 2,800 3.4 1.73 46 17.9 5.4 4 250 88 153 39 57 13 37 15.2 3.6 6.2

----,



Depth

Analyte Unit

TSCA-High Occupancy

Criteria9:


EPA RML11

(Industrial Soil):






CB-131 CB-132 CB-133 CB-134 CB-134 CB-135 CB-136 CB-137 CB-206A CB-206B CB-206C CB-2116 CB-2130 CB-2227B CB-227A CB-227B CB-227C CB-237A CB-237B Mar-16 Mar-16 Mar-16 Nov-15 Mar-16 Mar-16 Mar-16 Nov-15 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Concrete Floor Concrete Floor Concrete Floor Concrete Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor0-0.5 in. 0-0.5 in. 0-0.5 in. 0-3 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-3 in. 0-0.5 in. 0.5-1.5 in. 1.5-3 in. 0-0.5 in. 0-0.5 in. 0.5-1.5 in. 0-0.5 in. 0.5-1.5 in. 1.5-3 in. 0-0.5 in. 0.5-1.5 in.

ND 2.2 ND ND 0.55 0.56 ND ND ND ND ND 1.6 0.64 ND ND ND ND ND ND1.2 17 7.1 0.79 2.7 1 1.4 2.7 91 43 5.7 3.1 1.7 3,300 16,000 3,100 1,400 9.4 0.37ND ND ND 0.45 ND ND ND 2.6 ND ND ND ND ND ND ND ND ND 13 0.180.87 7.2 4.2 NR ND ND ND NR ND ND ND ND ND ND ND ND ND ND NDND ND ND ND ND ND ND ND ND ND ND ND 0.55 ND ND ND ND ND ND2.07 26.4 11.3 1.2 3.25 1.56 1.4 5.3 91 43 5.7 4.7 2.89 3,300 16,000 3,100 1,400 22.4 0.55

-



Depth

Analyte Unit

TSCA-High Occupancy

Criteria9:


EPA RML11

(Industrial Soil):






CB-237C PT-100 PT-101 PT-102 PT-103 Wall-01 Wall-02 Wall-03 Wall-04 Wall-05 Wall-06 Wall-07 Wall-08 Wall-09 Wall-10 Wall-11 Wall-12 Wall-13 Wall-14 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15Concrete Floor Putty/Glaze Putty/Glaze Putty/Glaze Putty/Glaze Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall1.5-3 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in.

ND ND 1.8 1.5 0.76 0.97 1.1 ND 0.61 ND ND ND ND 0.56 ND 0.29 ND 2.2 0.770.12 12 0.76 7.3 1.6 1.2 2.9 0.22 0.66 72 0.24 8.2 8.2 0.59 0.55 0.38 62 2.1 1.5ND ND ND ND ND 0.48 ND ND ND ND ND ND ND ND ND ND 17 ND NDND ND ND ND ND NR NR NR NR NR NR NR NR NR NR NR NR NR NRND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND0.12 12 2.56 8.8 2.36 2.65 4 0.22 1.27 72 0.24 8.2 8.2 1.2 0.55 0.67 79 4.3 2.3

- -



Depth

Analyte Unit

TSCA-High Occupancy

Criteria9:


EPA RML11

(Industrial Soil):






Wall-15 Wall-16 Wall-17 Wall-18 Wall-19 Wall-100 Wall-101 Wall-102 Wall-103 Wall-104 Wall-105 Wall-106 Wall-107 Wall-108 Wall-109 Wall-110 Wall-111 Wall-112 Wall-113 Nov-15 Nov-15 Nov-15 Nov-15 Nov-15 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in.

ND 0.28 ND ND ND 1.7 2.7 2.5 0.26 ND ND ND ND 1 0.11 ND 5.2 22 667.5 0.52 ND ND 0.16 4.5 3.8 2.9 0.12 4.4 0.57 9.8 2,500 5.1 0.83 0.24 2.8 ND NDND ND ND ND ND ND ND ND ND 1.4 ND 2.2 ND ND ND ND ND ND NDNR NR NR NR NR ND ND ND ND ND ND ND ND ND ND ND ND ND NDND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND7.5 0.8 ND ND 0.16 6.2 6.5 5.4 0.38 5.8 0.57 12 2,500 6.1 0.94 0.24 8 22 66

----,



Depth

Analyte Unit

TSCA-High Occupancy

Criteria9:


EPA RML11

(Industrial Soil):






Wall-114 Wall-115 Wall-116 Wall-117 Wall-118 Wall-119 Wall-120 Wall-121 Wall-2101 WB-01 WB-02 WB-03 WB-04 WB-100 WB-101 WB-2100 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Mar-16 Nov-15 Nov-15 Nov-15 Nov-15 Mar-16 Mar-16 Mar-16Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Concrete Wall Wood Wood Wood Wood Wood Wood Wood0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-0.5 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-0.5 in. 0-0.5 in. 0-0.5 in.

ND ND ND ND 0.51 ND ND ND 2.6 15 33 18 ND 2.7 ND 5.51,500 15 2.7 0.19 1.3 0.18 ND ND 3.5 7.1 17 11 2.6 ND 13 2.1ND ND ND ND ND ND ND ND ND ND 13 8.5 ND ND ND NDND ND ND ND ND ND ND ND ND NR NR NR NR ND ND NDND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND1,500 15 2.7 0.19 1.81 0.18 ND ND 6.1 22.1 63 37.5 2.6 2.7 13 7.6

I~

.----------,

Table 3Bulk Asbestos Results - March 2016Keddy Mill Superfund SiteWindham, Maine

Location ID ACM-100 ACM-101 ACM-102 ACM-103 ACM-104 MC-100 MC-101Sample Date 42430 42430 42430 42430 42430 42430 42430Sample Type Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor Concrete Floor

Depth 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in. 0-3 in.

Analyte UnitActinolite % ND ND ND ND ND ND NDAmosite % ND ND ND ND ND ND NDAnthophylite % ND ND ND ND ND ND NDChrysotile % 1 1 20 10 20 trace NDCrocidolite % ND ND ND ND ND ND NDTremolite % ND ND ND ND ND ND ND

Notes:ND = Not DetectedSource: Weston Solutions, Inc., 2016

Table 4Potential Chemical - Specific StandardsKeddy Mill Superfund SiteWindham, Maine

Media Authority Requirement Status Requirement Synopsis Action to Be TakenGuidelines for Carcinogenic Risk

AssessmentEPA/630/P-03/001F

To Be Considered These guidelines provide guidance for developing risk-based remediation standards.TBC in developing ICs that will ensure that any materials left behind will not create

a carcinogenic risk.

Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure

to CarcinogensEPA/630/R-03/003F

To Be Considered This provides guidance for developing risk based remediation standards.TBC in developing ICs that will ensure that any materials left behind will not create

a carcinogenic risk to children.

EPA Risk Reference Doses (RfDs) To Be ConsideredGuidance used to compute human health hazard risk reference doses (RfDs) resulting from exposure to non-carcinogens in site

media. RfDs are considered to be the levels unlikely to cause significant adverse health effects associated with a threshold mechanism of action in human exposure for a lifetime.

TBC in developing ICs that will ensure that any materials left behind will not create a carcinogenic risk.

Human Health Assessment Cancer Slope Factors (CSFs)

To Be ConsideredCSFs are estimates of the upper-bound probability of an individual developing cancer as a result of a lifetime exposure to a

particular concentration of a potential carcinogen. These guidelines provide guidance on conducting risk assessments involving carcinogens and for developing risk-based remediation standards.

TBC in developing ICs that will ensure that any materials left behind will not create a carcinogenic risk.

EPA Carcinogenic Assessment Group Potency Factors

To Be Considered These guidelines provide guidance for developing risk-based remediation standards. TBC in developing ICs that will ensure that any materials left behind will not create

a carcinogenic risk.

Soil/Debris

Guidance on Remedial Actions for Superfund Sites with PCB

Contamination EPA-540-G-90-007 (August 1990)

To Be Considered EPA Guidance for developing risk-based remediation standards for risks posed by PCBs at Superfund sites.

TBC in developing remediation standards for removing PCB-contaminated building materials from the Site. Also the guidance will be used to develop ICs that will

ensure that any PCB contaminated materials left behind will not pose an unreasonable risk to public health and/or the environment.

SoilFederal Criteria, Advisories, and

Guidance

Keddy Mill EECA

Table 5Potential Location - Specific StandardsKeddy Mill Superfund SiteWindham, Maine

Protected Resource Authority Requirement Status Requirement Synopsis Action to Be Taken

Clean Water Act (CWA)Section 404 (40

CFR 230.10, 33 CFR 320-330)Applicable

For discharge of dredged or fill material into water bodies or wetlands, there must be no practical alternative with less adverse impact on aquatic ecosystem; discharge cannot cause or contribute to violation of state water quality standard or toxic effluent standard or

jeopardize threatened or endangered (T&E) species; discharge cannot significantly degrade waters of U.S.; must take practicable steps to minimize and mitigate adverse impacts; must evaluate impacts on flood level, flood velocity, and flood storage capacity. Sets

standards for restoration and mitigation required as a result of unavoidable impacts to aquatic resources. EPA must determine which alternative is the “Least Environmentally Damaging Practicable Alternative” (LEDPA) to protect wetland and aquatic resources.

Demolition of the mill building over and adjacent to the river may impact federal jurisdictional wetlands. Activities effecting wetlands will be conducted in accordance with these requirements including, but not limited to, mitigation and/or restoration in place. EPA has determined the partial demolition alternative is the LEDPA because (a) there is no practical alternative method that will achieve cleanup objectives with less adverse impact and (b) all practical measures will be taken to minimize and mitigate

any adverse impacts from the work. Public comment will be solicited on EPA’s LEDPA finding in the EE/CA.

Fish and Wildlife Coordination Act,16 USC § 661 et seq.

ApplicableRequires consultation with appropriate agencies to protect fish and wildlife when federal actions may alter waterways. Must develop

measures to prevent and mitigate potential loss to the maximum extent possible. Must provide notice of action to FWS. Consultation with appropriate federal agencies will be maintained during planning and

implementation of the alternative since it will alter protected resource areas.

Wetlands and Floodplains

Floodplain Management andProtection of Wetlands

44 C.F.R. § 9

Relevant and Appropriate

FEMA regulations that set forth the policy, procedure and responsibilities to implement and enforce Executive Order 11988 (Floodplain Management) and Executive Order 11990 (Protection of Wetlands). Prohibits activities that adversely affect a federally-regulated wetland unless there is no practicable alternative and the proposed action includes all practicable measures to minimize

harm to wetlands that may result from such use. Requires the avoidance of impacts associated with the occupancy and modification of federally-designated 100-year and 500-year floodplain and to avoid development within floodplain wherever there is a practicable

alternative. An assessment of impacts to 500-year floodplain is required for critical actions – which includes demolishing contaminated facilities within a floodplain. Requires public notice when proposing any action in or affecting floodplain or wetlands.

Federal jurisdictional wetlands altered by the building demolition will be restored in place. All remedial work within the regulated 500-year floodplain will result in no significant net loss of flood storage capacity and no significant net increase in flood

stage or velocities. Floodplain habitat will be restored, to the extent practicable. Public comment will be solicited as part of the EE/CA concerning any proposed alteration to

federal jurisdictional wetlands and floodplain.

Maine Natural Resources Protection Act (NRPA) 38 MRSA 480-A,B,C,D,V; 06-096

CMR c.305 Applicable

Prohibits certain activities in, on, over or adjacent to a protected natural resource, including rivers, without a permit. Activities include construction, repair or alteration of any existing structure. Activities may not cause unreasonable soil erosion or harm to

habitats or fisheries. Applicable to river impacts.

State riparian resource areas altered by the building demolition will be restored in place. All remedial action conducted within 75 feet of a state regulated resource area will comply with these regulations. Mitigation of impacts on State riparian resource

areas will be addressed.

Maine Mandatory Shoreland Zoning Act38 MRSA §§ 435-449;

06-096 CMR 1000Applicable Protects and conserves shoreland areas located within 250 feet of the high water mark as defined in state law.

Activities within 250 feet of the high water mark of the Presumpscot River will be conducted in compliance with this provision.

Maine Water Classification Program38 MRSA, Section 467

ApplicableThis program sets forth standards for the classification of Maine’s water. Presumpscot River is classified as Class B. Activities in a

water body cannot lower water quality below the designated classification.Site activities will be designed and implemented in a manner that does not degrade the

chemical, physical, or biological integrity of the Presumpscot River.

Wetlands and Floodplains

Maine Natural Resources Protection Act (NRPA); Maine Wetlands and Waterways

Protection 06-096 CMR 310Applicable

The regulations prohibit activities which would have an unreasonable impact on wetlands. Applies to alteration of freshwater wetlands or rivers, among other protect resources. The standards require that alterations to protected natural resources be avoided

where possible, and if it can be demonstrated that no practicable alternative exists, then the applicant must show that the amount of the resource affected has been minimized to the greatest extent practicable. All projects in or adjacent to (within 75 feet of) wetlands of

special significance and rivers, streams, and brooks require a permit. Applicable for impacts to river and wetlands as a result of building demolition.

State wetland resource areas altered by the building demolition will be restored in place. All remedial action conducted within 75 feet of a state regulated wetland resource area will comply with these regulations. Mitigation of impacts on State

wetland resource areas will be addressed.

Dams

Maine Waterway Development and Conservation Act (MWDCA)

Title 38 Chapter 5, SS 630-638, 06-096 CMR c.450


Requires that a permit be issued for the construction, reconstruction, or structural alteration (including some maintenance and repair) of new or existing hydropower projects. Relevant and appropriate due to proximity to hydroelectric dam.

Demolition of the building will be conducted in a manner that does not impair the operation or safety of the adjacent hydroelectric dam.

Endangered Species

Maine Endangered Species Act and Regulations

12 MRSA Chapter 925Sections 12801-12810, 09137 CMR 08

Applicable if endangered species

are present

Establishes wildlife sanctuaries, lists state endangered and threatened species, and specifies conditions for take of threatened or endangered species. There are 22 endangered species in Maine and 23 species listed as threatened under Maine's Endangered Species

Act. Possible endangered bat habitat in building to be demolished.

Demolition of the building will be conducted in a manner that does not harm listed bat species.

Wetlands/Aquatic Habitat

Federal Criteria, Advisories, and

Guidance

State Criteria, Advisories, and

Guidance

Wetlands/ Waterways

Keddy Mill EECA

Table 6Potential Action - Specific StandardsKeddy Mill Superfund SiteWindham, Maine

Media/Remedial Action Authority Requirement Status Requirement Synopsis Action to Be Taken

Hazardous Waste

Resource Conservation and Recovery Act, RCRA Subtitle C; Hazardous Waste Identification and Listing

Regulations, Generator and Handler Requirements 42 U.S.C. §9601 et seq.

40 CFR Parts 260-262 and 264

Applicable/Relevant and Appropriate

Federal standards used to identify, manage, and dispose of hazardous waste. Maine has been delegated the authority to administer these standards through its state hazardous waste management regulations.

Relevant and Appropriate for hazardous waste left in place; Applicable for any hazardous wastes generated as part of a cleanup (e.g., excavated soil/debris)

While no hazardous wastes have been identified on the Site to date, any wastes generated by the building demolition will be analyzed under these standards to determine whether they meet characteristic hazardous waste standards. If identified, any hazardous wastes generated will be managed and disposed of off-site at a

licensed facility. Non-hazardous materials will be disposed appropriately.

Air

Clean Air Act; National Emission Standards for Hazardous Air

Pollutants42.U.S.C. § 112(b)(1); 40 C.F.R. Part 61

ApplicableMaine has been delegated the authority to administer these standards through its state NESHAP

regulations. These regulations establish emissions standards for 189 hazardous air pollutants (including for asbestos (Subpart M)). Standards set for dust and other release sources.

Demolition of the building will be conducted in accordance with these regulations. No air emissions from remedial activities will cause air quality standards to be exceeded. Mitigation measures (e.g. wetting) will

be used to control the potential release of asbestos and dust during demolition and the management of building debris.

National Pollutant Discharge Elimination System

(40 CFR 122-150, 122.26 stormwater discharges)

ApplicableEstablishes the specifications for discharging pollutants from any point source into the waters of the U.S.

Also includes stormwater standards for activities disturbing more than one acre.

Demolition of the building will be managed to prevent stormwater discharges from the Site. To the extent water generated from the remediation needs to be discharged to the river, applicable discharge standards

will be met.

Clean Water Act, National Recommended Water Quality Criteria (NRWQC); 33 U.S.C. § 1314, 40 CFR

Part 131


NRWQC are provided by EPA for chemicals for both the protection of human health and the protection of aquatic life.

Used to establish monitoring standards for surface waters and sediments to assess the protectiveness of the building demolition and the management debris/soil generated by the demolition.

PCB-Contaminated Building Materials

Toxic Substances Control Act 40 CFR Part 761 Subpart D

ApplicableTSCA regulates building materials impacted from PCB remediation waste at concentrations of < 1 ppm in

high occupancy areas, < 25 ppm for low occupancy areas, and < 50 ppm for low occupancy areas if the site is secured by a fence marked with a sign including the ML mark. .

Applicable for characterizing PCB-contaminated building debris for disposal.

PCB-Bulk Remediation Waste

Toxic Substances Control Act40 CFR 761.61(a)(5)

ApplicableRequirements for off-site disposal of bulk PCB remediation wastes, and porous and non-porous PCB

remediation waste. Bulk PCB remediation waste will be managed and disposed of off-site in accordance with these standards

PCBsToxic Substances Control Act

40 CFR 761.61 (c)Applicable

This section of the TSCA regulations provides risk-based cleanup and disposal options for PCB remediation waste based on the risks posed by the concentrations at which the PCBs are found. Written approval for the

proposed risk-based cleanup must be obtained from the Director, Office of Site Remediation and Restoration, USEPA Region 1 and will be provided at the time of the Action Memo.

Building demolition and site restoration of areas with PCB-contaminated debris/soil that poses a human health risk or ecological risk will be implemented in a manner to prevent any unreasonable risk to human health or the environment. Remedial measures will be based on in-situ PCB concentrations in debris/soil.

AsbestosToxic Substances Control Act

(Transport and Disposal of Asbestos Waste) 40 CFR Subpart E, Appendix D

ApplicableProvides standards for transport and disposal of materials that contain asbestos. Requires proper wetting

and containerization. Asbestos will be managed in compliance with these standards.

Development and Evaluation of Consensus-Based Sediment Quality Guidelines for Freshwater Ecosystems Probable Effects

Concentrations (PECs)

To Be Considered The PEC level is the concentration above which the adverse effects on sediment-dwelling organisms are likely to occur.

The guidance will be used to develop monitoring standards for the Presumpscot River during the demolition.

Ontario Ministry of Environment and Energy (OMEE) Severe Effect Levels

(SELs) for Freshwater SedimentTo Be Considered The SEL level is the concentration at which the majority of the sediment-dwelling organisms are affected.

The guidance will be used to develop monitoring standards for the Presumpscot River during the demolition.

Hazardous/Solid WasteMaine Hazardous Waste, Septage and

Solid Waste Management Act38 MRSA § 1301 et seq.

ApplicableMaine is delegated to administer RCRA through its State statute and regulations promulgated under it.

Asbestos is identified as a special waste under this Act.Statutory requirements for generating/managing hazardous and solid waste during building demolition

will be complied with.

Maine Identification of Hazardous Wastes 38 MRSA § 800, 850

Applicable State regulations for the identification of hazardous waste.

While no hazardous wastes have been identified on the Site to date, any wastes generated by the building demolition will be analyzed under these standards to determine whether they meet characteristic hazardous waste standards. If

identified, any hazardous wastes generated will be managed and disposed of off-site at a licensed facility. Non-hazardous materials will be disposed appropriately.

Maine Standards for Generators of Hazardous Waste 06-096 CMR c. 851

Applicable This rule establishes standards and requirements for persons who generate hazardous waste. If identified, any hazardous wastes generated will be managed and disposed of off-site at a licensed facility.

Solid WasteMaine Solid Waste Management Rules

06-096 CMR c. 400, 411Applicable State regulations for the management and transport of solid waste. Applicable to solid waste generated during building demolition.

Solid Waste/Asbestos

Maine Solid Waste Management Rules: 06-096 CMR c. 425

Chapter 425 - Asbestos Management Regulations

ApplicableThese rules and regulations apply to asbestos abatement activities, including removal, encapsulation,

demolition, enclosure, repair, and handling, and associated activities such as inspection, design, analysis, monitoring, and training, conducted in the State of Maine.

Applicable to handling of asbestos during building demolition.

Surface WaterMaine Surface Water Quality Criteria

for Toxic Pollutants 06-096 CMR c. 584Relevant and Appropriate

This rule establishes ambient water quality criteria for toxic pollutants in the surface waters of the State. The rule also sets forth procedures that may be used to determine alternative statewide criteria or site-

specific criteria adopted as part of a licensing proceeding.

Used to establish monitoring standards for surface waters and sediments to assess the protectiveness of the building demolition and the management debris/soil generated by the demolition.

Stormwater

Maine Erosion and Sedimentation Control Act; Stormwater Management Rules 38 MRSA 420-C,D; 06-096 CMR

500Applicable

A person who conducts, or causes to be conducted, an activity that involves filling, displacing or exposing soil or other earthen materials shall take measures to prevent unreasonable erosion of soil or sediment beyond the project site or into a protected natural resource as defined in section 480-B. Erosion control

measures must be in place before the activity begins. Measures must remain in place and functional until the site is permanently stabilized. Adequate and timely temporary and permanent stabilization measures

must be taken and the site must be maintained to prevent unreasonable erosion and sedimentation. Stormwater regulations apply to, among other things, a project that disturbs one acre or more of land area.

Demolition of the building will be managed to prevent stormwater discharges from the Site.

State Statute/ Regulation

Surface Water Federal Statute/ Regulation

Surface Water/ SedimentFederal Criteria, Advisories, and

Guidance

Hazardous Waste

Keddy Mill EECA

Table 6Potential Action - Specific StandardsKeddy Mill Superfund SiteWindham, Maine

Media/Remedial Action Authority Requirement Status Requirement Synopsis Action to Be Taken

Air/AsbestosMaine Asbestos Law and Regulations

38 MRSA §1280; 06-096 CMR c. 425Applicable

Establishes criteria and procedures of acceptable work practices for asbestos abatement activities including wetting of ACM, containerization, etc. Storage of asbestos waste is also regulated by this rule.

Applicable to handling of asbestos during building demolition.

AirMaine Protection and Improvement of

Air Act; NESHAP regulations38 MRSA §585-B; 06-096 CMR c. 144

Applicable Maine is delegated to administer the federal NESHAP standards through its State air statute and the State

NESHAP regulations promulgated under it. These regulations formally adopts the federal NESHAPS, including Subpart M; National Emission Standard for Asbestos.

Demolition of the building will be conducted in accordance with these regulations. No air emissions from remedial activities will cause air quality standards to be exceeded. Mitigation measures (e.g. wetting) will be used to control

the potential release of asbestos and dust during demolition and the management of building debris.

AirMaine Dept. Health Services, Maine

Ambient Air GuidelinesTo Be Considered Guidelines for monitoring air quality and preventing releases of air contaminants.

These guidelines will be considered with respect to monitoring air quality and preventing release of contaminated dust during demolition activities.

Erosion ControlMaine Erosion and Sediment Controls

Best Management Practices (BMP), 3/2003, DEPLW0588, updated 2014

To Be Considered Describes BMP for any projects disturbing soil or removing a natural ground cover. Guidance will be considered in addressing erosion/ sediment control measures during building demolition and site

restoration.

State Criteria, Advisories, and

Guidance

State Statute/ Regulation

Keddy Mill EECA

Table 7Alternative 2 - Soldier Pile & Concrete Lagging Wall Opinion of Probable CostsKeddy Mill Superfund SiteWindham, Maine

Depth Area Volume Mass

Unit No. of Cost per CostUnits Unit

INDIRECT COSTSPlanning Documents and Engineering

Permitting lump 1 $75,000 $75,000TSCA Risk Based Disposal Approval lump 1 $50,000 $50,000Coffer Dam Design lump 1 $50,000 $50,000Remedial design (plans & specs, risk review, bid docs, contractor selection) lump 1 $75,000 $75,000

Construction ManagementConstruction management (2 staff for H&S monitoring & contractor oversight) day 130 $5,000 $650,000Dust monitoring month 5 $10,000 $50,000Project management (contract administration, office field support, submittal review) day 130 $750 $97,500RA Report and record drawings lump 1 $35,000 $35,000

Subtotal Indirect Costs $1,082,500

DIRECT COSTSWest Wall Stabilization - Soldier Pile and Concrete Lagging

Geotechnical Explorations lump 1 $30,000 $30,000Geotechnical Design lump 1 $55,000 $55,000Mobilization and Access lump 1 $150,000 $150,000Temporary Stabilization - Soil Nail Wall lump 1 $360,000 $360,000Retaining Wall Construction lump 1 $340,000 $340,000

DemolitionMob/demob lump 1 $100,000 $100,000Contractor Submittals (HASP, etc.) lump 1 $25,000 $25,000Coffer Dam Installation foot 300 $1,000 $300,000Demolition - West Wing (Square foot of material) lump 1 $300,000 $300,000Demolition - Press Hall lump 1 $240,000 $240,000Demolition - East Wing lump 1 $220,000 $220,000

Concrete handling and Resizing (includes dust control) ton 10,400 $20 $208,000ACM Removal and Disposal tote 1 $700,000 $700,000Waste Classification Analyses (1 per 1,000 tons) sample 10 $1,000 $10,000TSCA PCB Remediation Waste >50ppm ton 5,200 $400 $2,080,000TSCA PCB Remediation Waste <50ppm ton 5,200 $160.00 $832,000

Subpart N sampling of soil each 350 $130 $45,500

RestorationTopsoil Installation and Procurement CY 500 $60 $30,000Streambank Restoration LF 200 $800 $160,000Streambank Plantings SY 2,000 $35 $70,000Erosion Matt SY 2,000 $8 $16,000

Subtotal Direct Cots $6,271,500

Project Total = $7,354,000

+Contingency 20% $8,824,800

Key AssumptionsConcrete is not RCRA HazardousNo Soil remediation is requiredNo utility relocation necessaryConcrete <50 mg/kg will be accepted at a non-hazardous landfill

Description

Page 1 of 3

Table 8Alternative 3 - Soil Nail Wall with Permanent Shotcrete Facing Opinion of Probable CostsKeddy Mill Superfund SiteWindham, Maine







DIRECT COSTSWest Wall Stabilization - Soldier Nail Wall With Permanent Shotcrete Facing

Geotechnical Explorations lump 1 $30,000 $30,000Geotechnical Design lump 1 $52,000 $52,000Mobilization and Access lump 1 $50,000 $50,000Initial Stabilization - Contingency for extra grouting in rubble fill lump 1 $100,000 $100,000Retaining Wall Construction lump 1 $360,000 $360,000









Description

Page 2 of 3

Table 9Alternative 4 - Reinforced Concrete Cantilever Wall Opinion of Probable CostsKeddy Mill Superfund SiteWindham, Maine







DIRECT COSTSWest Wall Stabilization - Reinforced Concrete Cantilever Wall

Geotechnical Explorations lump 1 $30,000 $30,000Geotechnical Design lump 1 $70,000 $70,000Mobilization and Access lump 1 $125,000 $125,000Temporary Stabilization - Soil Nail Wall lump 1 $360,000 $360,000Retaining Wall Construction lump 1 $300,000 $300,000









Description

Page 3 of 3

Table 10Summary of Comparative Analysis of Removal ActionsKeddy Mill Superfund SiteWindham, Maine

Aspects

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Alternative 1 - No Action 1 5 5 5 1 1 5 1 1 1 5 54

Alternative 2 - Soldier Pile and Concrete Lagging Wall 5 4 4 5 5 5 5 5 5 4.5 3 66.75

Alternative 3 - Soil Nail Wall with Permanent Shotcrete Facing 4 5 4 5 4 4 5 4 5 4.5 3.2 64.75

Alternative 4 - Reinforced Concrete Cantilever Wall 5 3 3 5 5 5 5 5 5 4.5 3.1 64.25

Notes:

2. Overall score = Summation (Rating x Weight)

Effectiveness Cost Overall Score

1. Ratings range from 1 (poor) to 5 (good); Ratings applied are relative subject appraisals of performance.

Criterion Implementability

ERM Page 1 of 1 Keddy Mill 11/29/2017

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Appendix A Structural Review of Mill Building

Structural Review of Mill Building Keddy Mill Superfund Site 7 Depot Street South Windham, ME

PREPARED FOR

ERM Consulting & Engineering, Inc. One Beacon Street, 5th Floor

Boston, MA 02108

November 28, 2017

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VIA E-MAIL Revised November 28, 2017 File No. 09.0025957.00 Steven J. Drechsler, P.E. Alfred Benesch & Company 90 National Drive Glastonbury, Connecticut 06033 Re: Revised Report on Geotechnical Engineering Services Retaining Wall Evaluation Abandoned Mill Building 7 Depot Street Windham, Maine Dear Steven: GZA GeoEnvironmental, Inc. (GZA) is pleased to submit this revised report for geotechnical engineering services for the subject project. Our work was completed in accordance with the September 29, 2017 Alfred Benesch & Company-GZA Subconsultant Services Agreement which includes the scope of GZA’s September 22, 2017 proposal No. 09.P000057.18. Our work is subject to the Limitations included in Appendix A. BACKGROUND The project concept includes demolition of the abandoned mill buildings including the maintenance shop and melt building that are adjacent to the left river bank (looking downstream) of the Presumpscot River in Windham, Maine, just downstream from the existing Sappi dam and hydro power plant. The engineering and planning of building demolition is being undertaken by ERM. GZA will focus on the geotechnical aspects of foundations and alternative concepts for a permanent retaining wall to be located at the upstream end of the building demolition work area. Alfred Benesch & Company (Benesch) provided several documents and reports for GZA’s review and use in completing this evaluation, including the following:

February 27, 2007 Oak Engineers Geotechnical Investigation;

June 12, 2007 Oak Engineers Structural Condition Investigation Report;

March 22, 2016 CES Conceptual Demolition Plan Summary Report; and

September 6, 2017 Northeast Archaeology Research Center Archaeological Phase 0 Assessment and Architectural Assessment of the Keddy Mill Superfund Site.

Proactive by Design

GEOTECHNICAL

ENVIRONM£NTAL

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477 Congress Street

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T: 207.879.9190

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www.gza.com

Revised November 28, 2017 Alfred Benesch & Company

09.0025957.00 Page | 2

Proactive by Design

An Equal Opportunity Employer M/F/V/H

DATA REVIEW

GZA reviewed the above-referenced report documents, the mapped surficial and bedrock geology of the site, and our project files for pertinent subsurface information from GZA projects near the site. The focus of the review was the historic sequence of structures at the at the upstream end of the building demolition work area, where a new retaining wall is under consideration. For purposes of this document this area will be called the conceptual retaining wall location.

SITE VISIT

GZA’s Christopher Snow, P.E. visited the site with Steven Drechsler, P.E. of Benesch on October 2, 2017 and observed soil, bedrock and water conditions visible at the ground surface. During the visit, GZA was able to observe the visible portions of existing foundations, retaining walls and underground structures beneath the maintenance shop and melt building. INTERPRETATION OF EXISTING CONDITIONS Historic data revealed that at some point between 1871 and 1885, the Sebago Wood Board Company built a three story, brick mill building along the left bank of the Presumpscot River. Photos show the building was supported on a stone masonry base with four integral, brick, arch culverts that exited on the downstream side of the building. Around 1906, the Androscoggin Pulp Company built the Beater Building and Machine Shop, consisting of multi-story, reinforced concrete addition structures. Foundations for the additions were visible in the river during the site visit and were observed to consist of square spread footings, apparently built within the river, inside of timber cofferdams. The base floor level of the beater building consists of a reinforced concrete (structural) slab system, suspended above the flowing river. Based on the historical data, the conceptual retaining wall location is interpreted to be within the limits of the beater building, adjacent to the downstream side of the old mill building where it meets the upstream edge of the beater building. Additional owners used the site and made modifications for more recent metal manufacturing operations, but the basic foundation structures appear to remain in place at the conceptual retaining wall location. Most of the old mill building was demolished, however, portions of the stone masonry base remain in place. During the site visit, the stone masonry base was visible to a height of about 8 to 10 feet above the beater building floor, and a brick wall extended above that level. The brick wall is interpreted to be the remnant of the downstream exterior wall of the old mill building. Approximately 2 feet of the top of each of the four brick arch culverts was observed to extend above the beater building floor, and appeared to have a variable amount of miscellaneous and rubble fill. Variable amounts of flowing water were audible and or visible in three of the four arch structures. A surficial inflow to the arch culvert area was observed from the Presumpscot River, upstream of the dam.


09.0025957.00 Page | 3

Proactive by Design


GEOTECHNICAL ENGINEERING EVALUATIONS

GZA completed preliminary engineering evaluations for the project, including: assessing the design subsurface profile and engineering properties relative to retaining wall support and stability; and developing conceptual alternatives for a new retaining wall to support the upstream limit of the proposed building demolition.

Design Subsurface Profile

The following materials have been encountered at the site, listed in descending order below existing ground surface:

Fill: Sand and gravel with varying amounts of brick, stone, mortar and concrete rubble.

Alluvial Deposits: Silts and fine sand with variable amounts of gravel and organics.

Bedrock: Foliated Schist with Rock Quality Designations of 68 to 73 where cored, indicating good quality rock.

Based on the massive nature of the old mill building foundations and superstructure, we anticipate that the structure is supported on spread footings bearing directly on bedrock. Based on the shape of the brick arches beneath the old mill building and the observed remnants of timber cofferdams and footings observed on the west side of the beater building, we anticipate that subsurface conditions at the conceptual wall location include man-made structures and rubble fill overlying bedrock. The depth to bedrock is unknown, but based on the previously referenced available information and observations made at the site, may be on the order of 6 to 12 feet below the beater building floor. Evaluation of Alternative Wall Types

Constructability of a wall at the conceptual wall location will be highly dependent on the depth to bedrock. The discussions that follow assume that bedrock is approximately 6 feet below the beater building floor level. This assumption should be confirmed using test borings. It appears that the beater building basement and first floor slabs currently act as struts that laterally support and restrain the existing brick wall at the conceptual wall location. Demolition and removal of these floor systems is likely to destabilize the existing wall. Therefore, it will be necessary to temporarily support the earth behind the existing brick wall, and the wall itself, so the beater building can be demolished. Temporary support could be in the form of wales with raker bracing, wales with rock-socketed tiebacks, soil nailing, or soldier beams and lagging. Wales with raker bracing is a technically feasible method to replace the existing strut support, but the rakers are impractical since they would be located in the expected demolition area. Rock-socketed tiebacks are technically feasible, but may be difficult to construct since the tiebacks would need to penetrate the brick arches and a potentially significant associated void space to reach the bedrock. Soil nailing with temporary shotcrete facing represents a more constructible solution since it can be performed in limited-access conditions with little or no demolition in advance. Although technically feasible


09.0025957.00 Page | 4

Proactive by Design


for temporary support, installation of soldier beams and lagging is anticipated to create significant disturbance near the existing brick wall due to vibration and modifications needed to access the locations with large drilling equipment. Therefore, soil nailing is considered the preferred alternative for initial stabilization of the existing brick wall. Technically-feasible permanent wall types include but are not limited to a reinforced concrete cantilever wall bearing on bedrock, a drilled soldier beam and lagging wall, and a permanent soil nail wall with shotcrete facing. Construction of the reinforced concrete cantilever wall or the soldier beam and lagging wall would require soil nailing or other temporary stabilization of the existing wall prior to construction. The drilled soldier beam and lagging and permanent soil nail wall systems could be installed on/through the existing floor. Several sketches are attached to illustrate the wall concepts. Sketch 1 shows the conceptual wall location and general elevation Sketches 2 through 4 show the three concepts for the permanent wall system. Given the suspect condition of the existing masonry and brick wall, there is potential risk for failure of the existing brick wall during stabilization operations. The use of soil nails and a reinforced concrete facing is intended to reduce this risk. Though some risk of destabilization of the existing wall also exists with the installation of the soil nail wall, the operation produces less vibration than soldier beam installation. Initial soil nail installation locations can be chosen to provide the greatest benefit for overall stability. Risk would be reduced with every successive anchor installation until the facing is completed and the existing wall is fully stabilized. Given that there is flowing water through the four brick arch culverts along the conceptual wall line, plugging the culverts would likely result in increased water pressures on the upstream face, that could lead to instability of the new wall, if not mitigated. Blockage may also change subsurface seepage patterns and has the potential to cause elevated hydrostatic pressures or other detrimental effects on the powerhouse and other walls nearby. Consequently, it will be necessary to consider means to divert the flow away from the upstream face of the new wall or design the wall to manage the seepage. The soil nail and soldier beam and lagging alternatives could have a base level at the top of the brick arches that would allow the brick arches to remain open to allow continued seepage. Water that might accumulate behind the cantilever wall alternative could be controlled using a foundation drainage system or French drain on the uphill side, that allows drainage through penetrations in the face. Conceptual Cost Estimates

GZA developed conceptual level cost estimates for three alternative wall concepts as summarized in the table that follows. It was assumed that the existing floor system would remain in place during construction until the new system provides lateral stability for the wall.


09.0025957.00 Page | 5

Proactive by Design


Wall Concept Geotechnical Explorations

Geotechnical Design

Mobilization / Access Stabilization Wall Conceptual

Cost Estimate

Reinforced Concrete Cantilever Wall $30,000 $37,000 $125,000

(porta-dam)

$360,000 (temp soil nail wall)

$300,000 $852,000

Soldier Beam and Concrete Lagging

Wall $30,000 $40,000 $150,000

$360,000 (temp soil nail wall)

$340,000 $920,000

Soil Nail Wall with Permanent

Shotcrete Facing $30,000 $37,000 $50,000

Integral ($100,000

contingency for extra

grouting in rubble fill)

$360,000 $577,000

RECOMMENDATIONS

Three technically-feasible alternatives are provided for the new retaining wall at the conceptual wall location: a soldier beam and concrete lagging wall, a soil nail wall, and a reinforced concrete cantilever wall. We assumed that construction of the reinforced concrete cantilever wall and the soldier beam and lagging wall would require installation of a temporary soil nail facing to support the existing brick wall until the new wall is completed. Significant uncertainty exists in the nature and consistency of the fill within the soil nail anchor zone, and the depth to, and nature of, the bedrock at the conceptual wall location. We recommend that a series of borings be drilled to assess the fill in the soil nail anchor zone and the depth and quality of bedrock along the conceptual retaining wall line to allow better interpretation of how the existing subsurface conditions will impact the wall type selection and design. The estimated cost of these geotechnical explorations is $30,000 as noted in the table above. We recommend that a program be developed to further assess the source of the water in the culverts, and evaluate means to divert or otherwise manage that flow such that it will not adversely affect existing or proposed structures. This seepage analysis should be completed, regardless of the selected design alternative. The design fees for each alternative include $12,000 to cover the estimated cost of a seepage analysis for this site. The table above provides the estimated costs for geotechnical design including seepage analysis, geotechnical engineering analyses for the wall system, and preparation of geotechnical aspects of contract plans and specifications.


09.0025957.00 Page | 6

Proactive by Design


CLOSURE

GZA appreciates the opportunity to support Benesch on this project. Please contact Chris Snow at 207-358-5118 should you have any questions or require additional information. Very truly yours, GZA GEOENVIRONMENTAL, INC.

Christopher L. Snow, P.E. Andrew R. Blaisdell, P.E. Associate Principal Consultant Reviewer CLS/ARB:erc P:\09 Jobs\0025900s\09.0025957.00 - Keddy Mill Windham Ret Wall\Report\REV1 25957.00 Benesch Windham Mill Geo RPT 112817.docx

Attachments: Sketch1 – Conceptual Wall Location Sketch 2 – Soldier Beam and Lagging Retaining Wall Concept Sketch 3 – Soil Nail Retaining Wall Concept

Sketch 4 – Reinforced Concrete Retaining Wall Concept Appendix A - Limitations

Sketches

GZA GeoEnvironmental, Inc. 4 77 Congress Street, Suite 700 Portland, Maine 04101 (207) 879-9190 Fax(207) 879-0099 http://www.gza.com

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GZA GeoEnvironmental, Inc. 4 77 Congress Street, Suite 700 Portland, Maine 04101 (207) 879-9190 Fax (207) 879-0099 http:/ /~.gza.com

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Appendix A – Limitations

Proactive by Design

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