213 Court Street, Suite 1100 • Middletown, CT 06457 • Tel 860.704.4760 www.tighebond.com

23-5005-016A

January 26, 2024

Helen Rosenberg

City of New Haven

Office of Economic Development

165 Church Street

New Haven, CT 06510

Re: Remedial Action Plan

198 River Street, New Haven, CT

(Formerly Proposed Parcel 198RS-C River Street)

Dear Helen:

Tighe & Bond has prepared this Remedial Action Plan (RAP) for a parcel of land totaling approximately 0.78 acres, currently addressed as 198 River Street in New Haven, CT (the

“site”). In June 2023, the 0.78-acre parcel, previously identified as proposed parcel 198RS-

C River St.) was legally subdivided from the larger parcel addressed as 198 River St. The purpose of this document is to outline the recommended approach to achieve compliance with the Connecticut Department of Energy & Environmental Protection’s (CTDEEP)

Remediation Standard Regulations (RSRs) and the Code of Federal Regulations (CFR) 40

Part 761 for polychlorinated biphenyls (PCBs). We understand that, in the near future, the

City plans to enroll the site in the Voluntary Remediation Program (VRP) pursuant to

Connecticut General Statutes (CGS) Section 22a-133x.

Introduction and Background

Tighe & Bond was retained by the City of New Haven (the “City”) to complete a

Supplemental Phase III Environmental Site Assessment (ESA) in accordance with the

CTDEEP Site Characterization Guidance Document (SCGD), dated September 2007 (revised

December 2010). The scope of the Supplemental Phase III ESA investigation is outlined in our original Agreement No. A22-0225 with the City for professional services, as extended by

Agreement No. A23-0639, effective March 1, 2023. Our Scope of Services under this

Agreement also includes preparation of this RAP.

Tighe & Bond was retained by the City under a separate Agreement (No. A23-0128, effective date March 1, 2023) to provide civil engineering services, including Site Plan design, for the proposed redevelopment of 198 River St., along with the recently subdivided

194 River St. (formerly proposed parcel 198RS-B, abutter to the east of 198 River St.) and

200 River St. (former proposed parcel 198RS-E, abutter to the south of 198 River St.).

Based on our ongoing coordination with the developer of 194, 198, & 200 River St., Bigelow

Square, LLC, the proposed redevelopment plan for the site (198 River St.) includes construction of an approximately 10,500 square foot, one-story, slab-on-grade commercial building, fronting on River St., and sitewide asphalt paved drives and parking areas. Sheet

C-101, included in Appendix A, is the most recent version of the proposed Site Layout Plan for redevelopment. The remedial strategy outlined in this RAP utilizes the proposed redevelopment as a key component of the remediation approach to maximize the cost-effectiveness and timeliness of remediation.

Based on the findings of the Supplemental Phase III ESA, Tighe & Bond identified nine on-site Areas of Environmental Concern (AOCs) where contaminants of concern (COCs) may have been spilled or released to the environment. The locations of the identified AOCs and confirmed Release Areas (RAs) are depicted on Figure 3. The AOCs were investigated by file://///srv/data/users/CC/Template/www.tighebond.com

- 2 -collecting concrete, soil, debris, and/or groundwater samples to evaluate whether releases of regulated compounds to the environment have occurred.

The investigation identified releases at seven of the on-site AOCs and fully delineated the extent of contamination at each in accordance with the SCGD. The interior of the building was not accessible during the Supplemental Phase III ESA due to the deteriorated condition of the building. Therefore, the extent of PCB contamination in interior concrete could not be delineated. The building was demolished on September 5, 2023, and the slab on grade remains in place. The required additional concrete samples will be collected prior to initiation of remediation.

Soil across the site was found to be impacted with multiple COCs at concentrations exceeding the CTDEEP RSR Residential (RES) Direct Exposure Criteria (DEC), Industrial/

Commercial (I/C) DEC, and/or the GB Pollutant Mobility Criteria (GB PMC), including PCBs, aromatic volatile organic compounds (AVOCs), extractable total petroleum hydrocarbons

(ETPH), semi-volatile organic compounds (SVOCs)/polynuclear aromatic hydrocarbons

(PAHs), and metals (arsenic and lead).

Soil, scrapyard debris entrained in shallow fill, and concrete slabs in several areas of the site, are impacted with PCBs at concentrations exceeding the RES DEC of 1 milligram per kilogram (mg/kg) provided in the RSRs. Due to the presence of PCBs detected in soil, concrete, and scrapyard debris (including concentrations >50 mg/kg in several soil and concrete samples), the site is regulated by the federal Toxic Substance Control Act (TSCA), pursuant to 40 Code of Federal Regulations (CFR) §761. The TSCA regulation requires remediation of the PCB contaminated concrete, soil, and entrained scrapyard debris identified at the site, and provides for three different regulatory pathways for remediation of

PCBs, including:

• “Self-Implementing” cleanup

• “Risk-Based” cleanup

• “Performance-Based” cleanup

Under current TSCA regulations, the first two cleanup options require preparation and submittal of Cleanup Plans to the U.S. Environmental Protection Agency (EPA) for review and approval. These options allow flexibility to leave PCBs in place at the site at concentrations >1 mg/kg, following site redevelopment, which for some remediation projects can save costs for off-site disposal.

Under the Performance-Based approach, all PCB contaminated material must be removed to achieve concentrations ≤1 mg/kg, which can result in higher costs for off-site disposal due to the increased volume of material requiring disposal to achieve the lower cleanup goal.

The Performance-Based approach also requires post-excavation verification sampling on a

5-foot grid, which adds analytical costs, along with disposal of all wastes as PCBs >50 mg/kg. One significant advantage of this option is it does not require submittal of a Cleanup

Plan to EPA for approval, which can save approximately 1 to 2 years in Plan preparation and final approval.

Based on the findings of our Supplemental Phase III ESA, report dated March 2, 2023, together with results from previous investigations, Tighe & Bond has determined that the most cost and time-effective option to facilitate redevelopment is to remediate the site to

≤1 mg/kg PCBs using the “Performance-Based” approach. While there are very high levels of PCBs in concrete and soil at the site, the extent of impacts appears localized and removal of impacted material to ≤1 mg/kg will not generate much more waste than if the remediation goal was set at 10 or 25 mg/kg, which are the typical maximum allowable PCB levels that may remain at a remediated site in Connecticut.

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Proposed Redevelopment Plan and Filling

The attached Sheet C-101, dated January 26, 2024, presents the current version of the proposed redevelopment site plan, designed by Tighe & Bond in coordination with the City and Bigelow Square, LLC. For 198 River St., the proposed redevelopment includes construction of an approximately 12,000 square foot, single story, slab-on-grade building, fronting along River St. The remainder of the site will be completely paved, with an entranceway from River St. in the northwest corner of the site, along with a sitewide asphalt parking area south of the building. 198 River St. will also be accessible from the abutting

194 River St. parcel to the east.

The eastern-abutting 194 River St. parcel (formerly Parcel 198RS-B), is impacted with multiple COCs in concrete, soil, scrapyard debris in fill, and groundwater at concentrations exceeding RSR and TSCA limits. The 194 River St. parcel is proposed to be temporarily capped with a parcel-wide asphalt paved parking lot that will provide parking for both 190

River St. and 198 River St. The temporary cap will be designed to be protective of human health, the currently proposed layout of which is also shown on Sheet C-101.

The southern-abutting 200 River St. parcel (formerly Parcel 198RS-E), is impacted with multiple COCs in concrete, soil, scrapyard debris in fill, and groundwater at concentrations exceeding RSR and TSCA limits. The 200 River St. parcel is also proposed to be temporarily capped with a parcel-wide asphalt paved parking lot that will provide a construction equipment and material storage yard for the business operating at the abutting parcel to the east (34 Lloyd St.). The temporary cap will be designed to be protective of human health, the currently proposed layout of which is also shown on Sheet C-101.

The site is located in a FEMA Special Flood Hazard Area (Zone AE), with a Base Flood

Elevation (BFE) of 11 ft above mean sea level (MSL). As currently required by the City of

New Haven, the Finished Floor Elevation (FFE) of the new building must be at least two feet above the BFE. The existing concrete slabs range in elevation from 5.5 to 9 ft above MSL.

The proposed building is slab-on-grade; therefore, a significant quantity of fill material will be required to raise the site grade to achieve an FFE of 13 ft. The elevation of the sidewalk along River St. to the north is approximately 7 ft, resulting in the FFE being 6 ft above the sidewalk.

Significant quantities of fill material will also be required to construct the surrounding paved parking area, and entranceway, which will slope down to the elevation of River Street. The proposed paved area south of the building will slope downward to the east and south, toward 194 and 200 River St. As shown on Sheet C-101, a short retaining wall will be constructed along the western parcel boundary.

Site Description & Vicinity

Refer to Figure 1 (Appendix A) for a site location map showing the site and surrounding area. The current configuration of the site is shown on Figure 2. The site is comprised of a single parcel of land, currently addressed as 198 River St. with a total area of approximately

0.78 acres. According to the City of New Haven Tax Assessor’s Card, the site is currently owned by the City, which acquired the parcel on November 20, 2006, from 198 River Street, LLC. The Assessor’s office identifies the parcel as Map/Block/Lot 175/608/202. The site is zoned as Light Industry/Light Industry-Marine (IL/IM) and has a surface elevation ranging from approximately 5.5 to 9 feet above the National Geodetic Vertical Datum.

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The site is located in a mixed commercial/industrial area. Public water and sanitary sewers are currently available to the site and site vicinity. The site is abutted by:

• To the north by River Street, beyond which is a large warehouse

• To the east by a vacant city-owned parcel currently address as 194 River St. (formerly identified as Parcel 198RS-B River St.)

• To the west by Phoenix Press, a commercial printing facility

• To the south by a vacant city-owned parcel currently address as 200 River St.

(formerly identified as Parcel 198RS-E River St.)

Site History

Until recently, the site was occupied by a deteriorating, vacant, approximately 4,000 square foot, slab-on-grade, brick, three story former factory building along the south side of River

St. The exact construction date of the portion of the existing building located in the site is unknown but historical records indicate it was constructed as early as 1869. The southern portion of the site consists of concrete slabs from former buildings that were demolished in phases between 2010 and 2015. The concrete slabs are currently overgrown with vegetation. On September 5, 2023, the remaining portion of the building was demolished.

Prior to development, the site was a low-lying area that was filled with polluted fill material reportedly originating from the Coppers Coke facility, which was also placed throughout the vicinity of the site on surrounding and nearby parcels along the Quinnipiac River, River St., and associated intersecting streets. Several parcels affected by the placement of this fill material have historically received approval of Widespread Polluted Fill (WPF) Variance requests from CTDEEP.

According to an Existing Facilities Condition Report, dated July 12, 2004, and Sanborn fire insurance maps, the original 3.25-acre 198 River St. parcel operated as a boiler and engine manufacturing company beginning in approximately 1869. The western and southern portions of the site were historically used as a plate iron works and boiler shop. The central portion of the existing building was used for storage on the upper levels and as part of the plate iron works on the first floor. The eastern portion of the existing building was used for pattern storage and a woodworking shop. The former building that occupied the eastern portion of the site housed the engine and boiler rooms. The specific processes conducted within the former on-site buildings are unknown but may have included metal working such as stamping, fabrication, and finishing associated with the plate iron works and boiler shop.

The site was most recently operated by Rockwell Heat Treatment Company (metal processing and heat-treating). All manufacturing activities reportedly ceased at the site sometime around 2005. The majority of the site is covered by concrete slabs associated with former portions of the building that were demolished in phases from circa 2010 to

2023. The remaining areas of the site are partially vegetated or bare ground, with several small debris/soil piles littering the property.

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Environmental Setting

Groundwater at the site is classified by CTDEEP as “GB”, which is presumed not suitable for human consumption without treatment. Based on information provided in the DTC 2016

Phase III ESA, groundwater flows in a northwesterly direction across the site. In July 2016, DTC installed pressure transducers in five wells across the original 198 River St. parcel including wells MW-103, MW-104, FSSMW-1, FSSMW-4, and FSSMW-7, shown on Figure 10.

The transducers took measurements every 15 minutes until they were removed on August

1st. Changes in water table elevation in each of the wells are as follows, in order of well location with distance from the river, starting with the well closest to the river:

• FSSMW-7 (40 feet from Mean High Water Line) = 1.5 to 2 feet

• MW-104 (100 feet from Mean High Water Line) = 1.5 feet

• MW-103 (100 feet from Mean High Water Line) = 0.15 foot

• FSSMW-4 (380 feet from Mean High Water Line) = 0.8 foot (located within the southern portion of the site)

• FSSMW-1 (460 feet from Mean High Water Line) = 0.05 foot (located 70 feet east of the site)

Based on the transducer data, the water table within the footprint of the site is tidally influenced to some degree, with about a 1 foot tidal fluctuation in the southern portion of the site.

The closest surface water body is the Quinnipiac River approximately 350 feet to the south of the site. The Quinnipiac River is classified by CTDEEP as Class “SB” which is water designated for use as; marine fish, shellfish and wildlife habitat, shellfish harvesting for transfer to approved areas for purification prior to human consumption, recreation, industrial and other legitimate uses including navigation.

The FEMA Flood Insurance Map (Map 09009C0442J), effective July 8, 2013, indicates that the entire site is located in a Zone AE, Special Flood Hazard Area, with a BFE of 11 feet.

Wetlands have not been identified at the site.

According to the Surficial Materials Map of Connecticut (U.S. Geological Survey, 1992), the site is underlain by sand and gravel overlaying sand, overlaying fines. According to soil borings completed in January through September 2016, the site is underlain by 0-10 feet of silt and fine sand, followed by 0-5 feet of silt and clay, followed by 0-3 feet of medium sand and silt. Anthropogenic fill material consisting of brick fragments, coal, ash, wood, and slag was observed in a few borings advanced at the site within the top 2.5 feet. A peat layer was also observed in some borings advanced at depths of 2 to 7 fbg that are indicative of marsh deposits. Tighe & Bond’s geological observations during the Supplemental Phase III ESA were consistent with observations made during previous investigations. Significant petroleum impacts, staining and odors, were observed at borings M-9 (4-7 fbg) and S-6B

(4-6.5 fbg). Anthropogenic materials observed in shallow fill material at several borings included: coated wire, plastic, rubber, foam, concrete, metal bits, brick, and glass.

According to the Bedrock Geologic Map of Connecticut (U.S. Geological Survey, 1985), the underlying bedrock beneath the site is New Haven Arkose, a reddish, poorly sorted arkose.

Bedrock outcrops were not observed at or within the immediate vicinity of the site.

However, two recently completed, deep geotechnical soil borings completed on-site by Welti encountered refusal at depths of approximately 35.5 feet (borings B-1 & B-2), inferred to be the bedrock surface.

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Previous Assessments

The following previous environmental assessments and reports for the site were reviewed prior to preparation of this RAP:

• Phase I ESA, TAQ, June 1996

• Phase I ESA, September 2001, Facility Support Services, LLC (FSS)

• Revised Phase II ESA Work Plan, March 27, 2003, GEI Consultants, Inc. (GEI)

• Phase II ESA Oversight Tasks, April 6, 2004, Triton Environmental, Inc. (Triton)

• Draft Phase II ESA, April 13, 2004, GEI

• Existing Facilities Condition Report, July 12, 2004, Allan Dehar Associates

• Supplemental Phase II ESA, December 2005, GEI

• PCB Spill Response & Characterization Report, October 2006, Triton

• Pre-demolition Hazardous Building Materials Inspection, November 2, 2007, Eagle

Environmental, Inc. (Eagle)

• Building Stabilization – Hazardous Materials Removal Plans, June 23, 2014, Eagle

• In-situ Waste Characterization Sampling – Engine Room Transformer Area, July 14, 2014, Eagle

• Building Demolition Abatement & Closures – Partial Floor & Roof Plans, September 10, 2014, Spiegel Zamecnick, & Shah, Inc.

• Post-Building Demolition PCB Verification Sampling – Former Transformer Area, June

8, 2015, Eagle

• Debris Cleanup & Site Stabilization Work Plan – Transformer Release Area, January

2016, FSS

• Phase I ESA Update, May 6, 2016, Diversified Technology Consultants, Inc. (DTC)

• Interim Remediation of Transformer Spill Area, May 2016, FSS

• Phase III ESA, October 28, 2016, DTC

• Phase I ESA Update, April 5, 2021, Tighe & Bond, Inc.

• Geotechnical Study for Proposed Warehouse, June 29, 2022, Welti Geotechnical, P.C.

• Supplemental Phase III ESA, March 2, 2023, Tighe & Bond

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Remediation Criteria

The soil and groundwater analytical results for all investigations were compared to the numeric criteria listed in the RSRs, Sections 22a-133k-1 through -3 of the Regulations of

Connecticut State Agencies (RCSA) with revision effective on February 16, 2021. The RSRs apply to any action taken to remediate polluted soil, surface water, or groundwater at or emanating from a release area, which action is required pursuant to Chapter 445, Chapter

446k, or Section 22a-208a(c)(2) of the Connecticut General Statutes (CGS), including, but not limited to, any such action required to be taken or verified by a Licensed Environmental

Professional (LEP). This includes parcels under an administrative order from CTDEEP, subsequent to a transfer of an “Establishment” under the CT Property Transfer Act (PTA)

CGS Section 22a-134a, sites that are enrolled in a VRP under CGS Sections 22a-133x or

22a-133y, and to remediation of certain solid waste disposal areas.

The site is not currently regulated under any state regulatory program, however, it is our understanding that the City will enroll the parcel in the VRP under CGS Section 22a-133x.

Based on the findings of the 2021 Phase I ESA Update, the site appears to meet the definition of an “Establishment”, therefore, a future transfer of ownership of the parcel could potentially be subject to the PTA.

PCBs have been released to the concrete slabs and soil at the site and are present at concentrations ≥50 mg/kg in both media. PCBs were also detected in debris observed in the shallow fill material (to a maximum depth of 3.75 fbg) at concentrations >1 mg/kg but all

<10 mg/kg. The debris is associated with the former scrapyard and is entrained in the fill material within the southeast corner of the site.

Pursuant to 40 CFR 761, PCB-contaminated soil, concrete, and scrapyard debris at the site are considered PCB-remediation waste. Due to the presence of PCB-remediation waste, the site is regulated under TSCA. In addition, the RSRs do not apply to the remediation of concrete and debris materials present in fill material.

The RSR numeric criteria are based on post-remediation property usage (industrial/ commercial or residential) and the CTDEEP groundwater quality designation (“GA” or “GB”).

The site is located in an area designated as “GB” quality groundwater. The site is zoned as

Light Industry. The current plan is to redevelop the site as a mixed commercial office/ warehouse, which will include construction of a new building, filling the area of the site where the proposed building will be located to achieve an FFE elevation of 13 ft above MSL, and construction of a paved entrance from River St. and a parking lot to the south of the new building. The City indicated that an Environmental Use Restriction (EUR) to render impacted soil inaccessible is an acceptable remedial option.

The 2021 RSRs do not provide soil and groundwater criteria for all substances detected at the site. In accordance with the RSRs, criteria may be developed and used for such

Additional Polluting Substances (APSs) with the approval of CTDEEP. The criteria for the

APSs detected at the site as listed in the data summary tables included with this report were obtained from Table 10: CTDEEP Recommended Criteria Values for Common Additional

Polluting Substances and Alternative Criteria Requests, dated September 2018.

For all detected COCs without 2021 RSR soil and groundwater criteria, a request for approval to utilize the CTDEEP’s pre-evaluated APS “Fast-track” numeric criteria will be submitted to CTDEEP for formal approval after the site has been enrolled in the VRP(y) program upon submittal of this RAP to CTDEEP and once a Remediation Site Identification

Number (REM ID) is assigned by CTDEEP.

The following is a summary of the RSR and TSCA numeric regulatory criteria that were used to evaluate COC concentrations in site soil, concrete, debris, and groundwater.

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Soil Criteria

Impacts to soil were compared to the following RSR and TSCA numeric regulatory criteria:

• The RSR Direct Exposure Criteria (DEC) to protect human health from potential risks associated with direct exposure to contaminated soil. In accordance with Section 22a-

133k-2(f)(2), the DEC (except for PCBs) do not apply to soil that has been rendered

“inaccessible” to human contact below a “cap” that either complies with the default requirements of the RSRs or is approved by CTDEEP as an Engineered Control.

• The RSR GB Pollutant Mobility Criteria (GB PMC) to protect groundwater quality from contaminants that could potentially migrate or leach from the soil to groundwater. In a

“GB” groundwater classification area, the GB PMC apply to soil located above the seasonal high water table. Based on gauging completed by Tighe & Bond and previous consultants, the depth to the seasonal high water table across the site ranges from approximately 2.4 to 3.5 fbg across the site.

The RSR soil criteria do not apply to concrete and debris, however, the remediation requirements of TSCA do apply to the PCB-contaminated concrete slabs and the scrapyard debris materials present in the fill material, along with PCB-impacted soil.

PCB concrete, soil, and debris analytical data were compared to the following TSCA cleanup criteria:

• ≤1 mg/kg – TSCA Unrestricted Use Criteria (also equals the RES DEC)

• ≤10 mg/kg – TSCA High Occupancy Use Criteria for soil below a cap or building (also equals the I/C DEC)

• ≤25 mg/kg – TSCA Low Occupancy Use Criteria for soil below a cap or building (also the maximum PCB concentration reportedly allowed by CTDEEP under an Engineered

Control to render material inaccessible.)

In addition, PCB concentrations were also compared to the two following TSCA PCB waste classifications:

• PCB Remediation Waste <50 mg/kg

• PCB Remediation Waste ≥50 mg/kg

Groundwater Criteria

Impacts to groundwater were compared to the following RSR numeric regulatory criteria applicable to sites located in “GB” classified groundwater areas:

• Groundwater Volatilization Criteria (GWVC) to protect human health from contaminants that may volatilize from contaminated groundwater into overlying buildings. Depth to groundwater at the site is less than 10 feet bgs, therefore, the

GWVC apply to groundwater at the site. Different GWVC may apply to a property, depending on land use, either “residential” or “industrial/commercial”, as defined by the RSRs. The less stringent I/C GWVC cannot be used unless an EUR has been recorded on the property deed restricting the site to industrial/commercial uses. A residential use restriction is not currently contemplated; therefore, the RES GWVC will apply to groundwater at the site unless such an EUR is filed. The analytical data tables include both the RES and I/C GWVC for comparison purposes.

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• Surface Water Protection Criteria (SWPC) to protect surface water bodies into which groundwater discharges. The only surface water body in the vicinity of the site is the

Quinnipiac River, which is located approximately 350 feet south of the site. Therefore, the groundwater analytical results were compared to the SWPC. In accordance with

Section 22a-133k-3(b), the RSRs allow calculation of Alternative SWPC (ALT SWPC) using the equation and site-specific variables provided in Section 22a-133k-3(b)(1)(B), for a coastal surface watercourse, to calculate a “Dilution Factor” which is then multiplied by the “applicable” CTDEEP Water Quality Criteria (WQC) provided in the

CTDEEP Water Quality Standards. Use of ALT SWPC requires notice to CTDEEP, including calculation backup. See Appendix C for the ALT SWPC calculated by Tighe &

Bond, in accordance with RSR Section 22a-133k-3(b)(1)(B) for a coastal surface watercourse, for ETPH detected in groundwater above the APS SWPC.

Non-Aqueous Phase Liquids

In accordance with Section 22a-133k-2(g)(1), the RSRs require removal of NAPL to the

“maximum extent practicable,” which is defined as the greatest degree of remediation that can be achieved using sound engineering and hydrogeologic practices without taking cost into consideration. However, CTDEEP may approve a request for a variance from the requirement to remove NAPL to the maximum extent practicable. If approved, an ELUR must be filed on the land records. Per the RSRs, all NAPL for which a variance is sought has been contained or removed to the maximum extent “prudent,” such that:

1. There is no migration of NAPL,

2. NAPL containing PCBs shall be remediated in compliance with 40 CFR 761,

3. Compliance with applicable groundwater criteria has been achieved, and

4. Compliance with the Soil Vapor Volatilization Criteria has been achieved for NAPL containing VOCs that is below a building.

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Areas of Concern & Release Areas

Based on the findings of the Supplemental Phase III ESA, Tighe & Bond identified 9 AOCs at the site where COCs may have been spilled or released to the environment and identified several releases on adjacent areas of the former 198 River St. parcel (currently 194 River

St. to the east and 200 River St. to the south) with the potential to impact the site. Based on a review of previous data and data obtained during the Supplemental Phase III ESA, releases were identified at 7 of the 9 on-site AOCs.

Areas immediately to the east and south of the site appear to be at least periodically upgradient of the site, as the subject area is somewhat tidally influenced due to its proximity to the Quinnipiac River. Groundwater data for upgradient portions of 194 River St.

and 200 River St. indicate the presence of impacted groundwater migrating onto the site.

Groundwater migrating onto the site appears primarily impacted with ETPH above RSR criteria, however, analysis by MA EPH indicates compliance with the RES GWVC. Tighe &

Bond assigned a Release Area (RA) number to the AOCs where releases were detected. The following AOCs and RAs were identified:

AOC 1 / RA-1 – Historical Industrial Operations (Site-Wide – Interior & Exterior)

AOC 2 – Potential Former Transformer Vault / Dry Transformer

AOC 3 – Former Transformer in Engine Room

AOC 4 / RA-2 – Former Engine Room, Boiler Room, & Pits

AOC 5 / RA-3 – Former Rolling Machine Pit & Floor Drains/Trenches

AOC 6 / RA-4 – Former Cutting Oil AST

AOC 7 / RA-5 – PCB-contaminated Transformer Spill

AOC 8 / RA-6 – Historical Site-Wide Urban Fill

AOC 9 / RA-7 – Historical Scrap Metal Operations

Refer to the Supplemental Phase III ESA for a detailed discussion of the Conceptual Site

Model (CSM). As indicated in that report, it is Tighe & Bond’s opinion that each of the AOCs have been fully investigated in accordance with the SCGD’s performance standards for

Phase III ESAs, except for defining the extent of interior PCB contaminated concrete slab associated with AOC 1, as described below. The nature, degree, and horizontal and vertical extents of releases have been adequately delineated at each AOC and the CSM has been refined and validated based on the sum total of the data obtained during all of the investigations conducted at the site. The following is a brief summary of the extent of identified contaminated concrete, soil, debris, and groundwater associated with each

AOC/RA and the associated current RSR and TSCA compliance status of each.

AOC 1 / RA-1 – Historical Industrial Operations (Site-Wide – Interior & Exterior)

The site has had over 150 years of various heavy industrial operations. Based on the site’s current condition (with many of the former buildings and other key features demolished or covered with debris) it is not possible to identify all potential former AOCs. In addition, the potential exists for multiple spills or releases throughout the site, some of which could be attributed to general site operations, and not associated with any particular AOC/RA.

Residual PCBs and petroleum detected in soil throughout the site could be attributed to RA-

1 because the presence of PCBs and petroleum in various locations throughout the site cannot be attributed to any particular AOC. Based on available soil data, it appears that there have been releases associated with RA-1 throughout the footprint of the site, including releases of petroleum and VOCs within the far northeastern portion of the former building.

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As shown on Figure 5A, low to moderate (<5 ppm) levels of PCBs were detected in exterior surficial/shallow soil to the southeast of the existing exterior concrete slab. The majority of the remainder of the exterior of the site is covered with concrete slabs that also had PCB detections in several areas at concentrations >1 to <10 ppm. Two areas of PCB impacted concrete with PCB >50 ppm were identified in locations that are associated with other

AOCs/RAs.

An area of interior concrete (within the currently existing portion of the building) was previously identified to be impacted with PCBs at concentrations >1 to <10 ppm (maximum of 1.3 ppm at sample C-123) and do not appear associated with any other identified

AOC/RA. In addition, low to moderate levels of petroleum, SVOCs, and VOCs were detected in exterior soil and groundwater across the site.

Due to a lack of documentation regarding historical site operations and chemical uses, it is possible that the presence of low to moderate PCB levels (in soil and concrete), petroleum, and VOCs in surficial and shallow soil and groundwater are due to miscellaneous spillage or releases not attributable to any specific AOC. However, it is also possible that the widespread low to moderate levels of PCBs in exterior surficial and shallow soil are due spreading of PCBs from other AOCs as result of substantial demolition and re-grading activities that have occurred over the years. Surface grades surrounding the existing slabs appear to have changed to some degree over time following demolition of the buildings.

RSR & TSCA Compliance Summary: The extent of exterior PCB contaminated concrete has been adequately delineated; however, the interior of the building was not accessible during the Supplemental Phase III ESA. Therefore, additional delineation of the previously identified area of PCB-contaminated interior concrete slabs (at sample C-123) is recommended, now that the building has been demolished, in order to define the extent of

PCB impacts at levels >1 ppm.

The PCB Performance-Based approach will be used to remediate concrete and soil at the site

(removal to achieve concentrations ≤1 mg/kg for both soil and concrete). Soil remediation

(excavation) will be required to bring the site into compliance with the RSRs and 40 CFR

761 for PCB impacted soil. Interior and exterior PCB-contaminated concrete will also require remediation (selective removal and disposal) to bring the RA-1 into compliance with 40 CFR

761.

AOC 2 – Potential Former Transformer Vault / Dry Transformer

Historical site plans depicted a former “transformer vault” to the east of the existing building. However, individuals knowledgeable of the site previously stated that AOC 2 was the location of a large, wall-mounted dry transformer. Based on the lack of physical documentation, it is not possible to determine the actual type of electrical equipment that may have been present within AOC 2. The potential transformer vault and/or dry transformer and the majority of the associated former electrical equipment are no longer present. Significant floor staining was not observed.

PCBs were detected in several concrete samples collected in the vicinity of AOC 2 at concentrations below 1 mg/kg (ranging from 0.53 to 0.7 mg/kg), similar to low-level PCBs levels detected in concrete throughout the site. Therefore, it is possible that the PCBs detected in concrete within the footprint of AOC 2 are attributable to other release areas within the building, located to the east of the site, including general industrial operations throughout the building and the nearby (but off-site) former machine shop and heat treating area where significant PCB impacts (well above 50 mg/kg) to soil and concrete were identified.

Based on the Supplemental Phase III ESA, it appears that a release has not occurred within

AOC 2. Tighe & Bond does not recommend any additional investigation and/or remediation associated with AOC 2.

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AOC 3 – Former Transformer in Engine Room

A transformer was previously located within the northwest corner of the engine room, adjacent to two pits in the slab. In 2007, an unlabeled transformer was present along with what appeared to be liquids that had spilled out onto an adjoining wall panel (since removed) and surrounding concrete floor, which remains in place. Tighe & Bond did not observe significant staining of the concrete slab in the area of the former transformer during this investigation. The removal date of the transformer and details regarding its handling and disposal are unknown. The potential PCB content of the former transformer is also unknown.

Several rounds of sampling were completed in 2007, 2014, and 2015 of soil, concrete slabs, brick walls, and debris/sediment atop the slab. In 2015, during partial demolition and stabilization of the building, debris and soil/sediment atop the slab in the area of the former transformer were removed. The concrete floor slab and pits remain within AOC 3.

As shown on Figure 9, PCBs were detected in two concrete samples at 2 and 8.6 ppm, taken from the immediate location of the former transformer. Concrete at the bottom of the nearby large pit was non-detect for PCBs. Concrete samples obtained on a 10 by 15-foot grid in locations to the south and east of the former transformer were all non-detect for

PCBs or <1 mg/kg.

Historically, samples of brick and mortar were collected from walls adjacent to the former transformer, including a former wall that divided the Engine Room from the adjacent room to the west, and from the exterior wall of the existing building located to the north of the transformer. All brick and mortar samples were non-detected for PCBs. Debris atop the slab in this area contained PCBs at 11 ppm.

Tighe & Bond advanced one boring (T-101) within AOC 3 to 8 feet below the slab at the immediate location of the former transformer. No evidence of soil impact (staining, odors, or elevated PID readings) was observed in shallow soil from 0 to 5 fbg. PCBs were not detected in samples T-101 (0-1’), (1-2’), and (4-5’), all with detection limits of ND<0.36 ppm. Brown to black soil was encountered at 5 fbg, likely associated with impacts from nearby RAs. ETPH was detected in soil sample T-101 (5-5.5’) at 390 mg/kg, below the RSR criteria.

Note, the 2021 Phase I ESA Update indicated that soil sample TP-1 (0-1’) with PCBs at 0.43 ppm was obtained from the vicinity of the former transformer, however, upon further evaluation, Tighe & Bond could not verify the specific location of TP-1. It is possible that this sample was obtained further to the east and is not representative of soil within AOC 3.

Therefore, this data has been eliminated from the current iteration of the CSM, resulting in

AOC 3 no longer being considered a Release Area.

RSR & TSCA Compliance Summary: Based on the findings of the Supplemental Phase III

ESA, it appears that spills of transformer fluid associated with AOC 3 have impacted a very limited area of concrete with PCBs up to 8.6 ppm, within the immediate vicinity of the former transformer. However, it does not appear that soil below the existing concrete slab has been impacted, therefore, a release does not appear to have occurred within AOC 3.

As shown on Figure 9, the horizontal extent of PCB-contaminated concrete attributable to

AOC 3 has been adequately delineated. Further investigation of AOC 3 is not recommended at this time.

The PCB-contaminated concrete will require remediation (selective removal and disposal) to bring AOC 3 into compliance with 40 CFR 761 using the PCB Performance-Based approach.

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AOC 4 / RA-2 – Former Engine Room, Boiler Room, & Pits

Several large boilers were located within the boiler room. The Engine Room contained steam driven machinery. Tighe & Bond observed four pits of unknown purpose within the footprint of the engine room that contained sediment and other debris. Tighe & Bond did not observe significant staining of the concrete slabs, except on a large concrete block structure that was mounted on top of the slab. The block structure was caked with a dry, thick, black, sludge-like coating. The former use of this structure is unknown.

PCBs were detected in the black dry sludge (sample “C-Scrape”) at 2.1 ppm. PCBs were detected in the concrete of the block structure in one of the side samples at 0.84 ppm and were not detected in the other two samples.

Within AOC 4, PCBs were detected in 1 of the 8 concrete slab samples at 0.38 ppm, which was obtained adjacent to the linear pit located along the eastern wall of the Engine Room.

Eight borings were advanced through the slab of the Engine Room and two borings were advanced through the slab of the Boiler Room. Soil below the Boiler Room at boring S-6 was observed to be black stained from 0 to 2 feet below the slab and then saturated with a yellow petroleum product at 4 to 5 feet below the slab. The yellow stained soil did not have an odor, and PID readings were <1 ppm. PCBs were not detected in any of the 18 samples taken from below the Engine & Boiler Room slabs. ETPH was detected in sample S-6 (4-5’) at 4,100 mg/kg. Tighe & Bond advanced boring S-6B to 12 fbg, adjacent to the original boring S-6. No soil was recovered in the upper 4 feet. Soil from 4 to 6 fbg was observed to be dark brown with a strong petroleum odor and a sheen on the standing water of the soil core. The PID reading on sample S-6B (4-6’) was 0.0 ppm.

PCBs and VOCs were not detected in samples from boring S-6B. ETPH exceeded the I/C DEC of 2,500 mg/kg in sample S-6B/MW-201 (4-6’) at 7,700 mg/kg. The depth to the seasonal high water table at well MW-201 has not been determined but is likely not higher than 6 fbg, therefore, the GB PMC also apply to this soil sample. Leachable ETPH by SPLP was not detected in sample S-6B/MW-201 (4-6’), indicating compliance with the GB PMC.

Sample S-6B/MW-201 (4-6’) was also analyzed for MA EPH as an alternative method. The

MA EPH C19-C36 hydrocarbon fraction was detected at 2,900 mg/kg, exceeding the APS GB

PMC of 200 mg/kg, the APS RES DEC of 1,000 mg/kg, and the APS I/C DEC of 2,500 mg/kg.

The C11-C22 hydrocarbon range was also detected at 960 mg/kg, exceeding the APS GB PMC of 30 mg/kg and the APS RES DEC of 500 mg/kg. Leachable MA EPH was not detected, indicating compliance with the GB PMC.

Well MW-201 was installed to evaluate the potential for LNAPL and gauged for LNAPL on

May 27, 2022 and July 13, 2023, with no measurable LNAPL present. A groundwater sample was not obtained from well MW-201.

RSR & TSCA Compliance Summary: Based on the Supplemental Phase III ESA, the horizontal and vertical extent of PCB impacted concrete and petroleum contaminated soil within RA-2 has been adequately delineated. Additional investigation associated with RA-2 is not recommended.

The concrete block structure requires decontamination or disposal to comply with 40 CFR

761 using the PCB Performance-Based approach due to the PCB detection in the dry black sludge at >1 but <10 ppm. PCBs were detected in one concrete sample at <1 ppm and does not require remediation.

Remediation will be required (an ELUR to render the soil inaccessible) to bring the ETPH impacted soil below the Boiler Room slab into compliance with the RES DEC. Soil within RA-

2 complies with the GB PMC as is. LNAPL does not appear to be present within RA-2.

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AOC 5 / RA-3 – Former Rolling Machine Pit & Floor Drains/Trenches

According to previous reports, multiple floor drains were observed in the southern exterior concrete slab, discharge locations unknown. Tighe & Bond did not observe evidence of floor drains; however, the slabs are partially covered with soil and debris, limiting observations.

Some of the former pits were backfilled with demolition debris or stone.

To date, the depth to the seasonal high water table within RA-3 ranges from 1.4 to 3.51 feet below the slab, which is the depth to which the GB PMC applies within RA-3.

Area of Borings H-6, I-6, & SB-55: In concrete, the highest PCB concentration was detected in sample C-58 at 57 mg/kg, which is located at boring I-6. PCBs were detected at levels <2 ppm in all surrounding samples, which were placed in all directions surrounding C-58 at distances of 10 to 20 feet away.

Tighe & Bond collected a composite concrete sample waste characterization sample that consisted of three grab samples from the vicinity of sample I-6. PCBs were detected at 1 mg/kg in sample I-6/WC-2, along with ETPH at 650 mg/kg and low concentrations of metals and AVOCs.

As shown on Figure 2, boring SB-55 was not located near any identified pits or trenches, however, high levels of contamination were observed and detected at this location. Soil at this boring was saturated with petroleum from 4.5 to 7 feet below the slab. Sample SB-55

(4-6’) contained PCBs at 718 mg/kg, exceeding the I/C DEC of 10 mg/kg. Leachable PCBs were detected at 16.1 mg/l, well above the GB PMC of 0.005 mg/l.

As shown on Figure 6, ETPH was detected at 3,380 mg/kg in sample SB-55 (4-6’), exceeding the I/C DEC. Low levels of metals were detected, below the RSR criteria.

As shown on Figure 7, the SVOC 1,2,4-TCB was detected at 69.8 mg/kg in sample SB-55

(4-6’), exceeding the GB PMC of 14 mg/kg. This sample was obtained from below the seasonal high water table within the location of SB-55, which is approximately 3 feet below the slab, therefore, the PMC do not apply.

One boring (I-5) was advanced at the reported location of SB-55. Except for two feet of urban fill (with brick & slag), no staining, odors, or elevated PID readings (all <1 ppm) were observed at boring I-5. The fill at and within the vicinity of boring I-5 was underlain by reddish brown fine sand and silt or a reddish brown silty sand. PCBs were detected in sample I-5 (0-2’) at 1.4 ppm.

Petroleum impacted soil (staining & slight odor) was encountered at boring I-6 (10 feet south of I-5) from 1 to 3 feet below the slab. PID readings were 1 ppm or less. As shown on

Figure 5A, PCBs were detected at very high levels in soil from 0 to 3 feet below the slab, including I-6 (0-1’) at 16,000 ppm, I-6 (1-2’) at 20,000 ppm, and I-6 (2-3’) at 1,100 ppm.

PCBs were also detected at 4-5’ at 160 ppm, 6-7’ at 27 ppm, and 8-9’ at 2.1 ppm.

As shown on Figures 7 and 8, very high levels of AVOCs and SVOCs were detected in sample I-6 (2-3’), including 1,2,4-TCB at 3,400 mg/kg, 1,2,4,5-TCB at 240 mg/kg, and 1,4-

DCB at 26 mg/kg, all exceeding the GB PMC. The level of 1,2,4-TCB in the I-6 (2-3’) sample also exceeded the I/C DEC. 1,2,4-TCB and 1,2,4,5-TCB were detected in sample I-6 (4-5’) above the GB PMC, however, this sample was obtained below the seasonal high water table.

Limited evidence of impact was observed in two of the multiple borings immediately surrounding boring I-6, including borings I-7 and H-6. Sample I-7 (0-2’) had moderate black staining. PCBs were detected in samples I-7 (0-2’) at 1 mg/kg, H-6 (0.7-1.7’) at 1.1 mg/kg, and H-6 (4-5’) at 0.46 mg/kg. Low concentrations of AVOCs were detected only in sample H-6 (4-6’), below RSR criteria. PCBs were not detected in any other samples obtained from the borings surrounding I-6. These results indicate that the extent of PCB and

AVOC/SVOC impacts in this area are well delineated.

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The presence of highly contaminated soil appears localized to the area of boring I-6. The concrete at I-6 is broken and/or missing, with the area of I-6 somewhat lower than the surrounding slabs. Based on these observations, it is possible that a floor drain or small pit may have been located within the area of boring I-6 that may have been the COC discharge point.

PCBs were detected in sample I-6/WC (0-8’) at 35 ppm.

Northern Machine Pit: Boring MW-12 was advanced adjacent to the northern rolling machine pit. Moderate “chemical” odors were observed from 5 to 8 feet. PCBs were detected at

0.133 mg/kg in sample MW-12 (0-4’). Low levels of SVOCs, ETPH, and metals were detected below the RSRs in sample MW-12 (0-4’) and (6-8’). VOCs were not detected in the

MW-12 (6-8’) sample.

Three borings, M-2, N-2.5, and O-4, were advanced adjacent to the pit. Evidence of impact was not observed at boring M-2, however, petroleum stained soil was encountered at borings N-2.5 at 0.4 to 1.2 ft below the slab and O-4 from 5 to 14 ft below the slab. PCBs were not detected in the 0-2’ samples obtained from the three borings and the O-4 (5-7’) sample. ETPH was detected in sample O-4 (5-7’) at 5,400 mg/kg.

Based on this information, it appears that a release of ETPH may have occurred from the pit resulting in soil impacts exceeding the I/C DEC. ETPH impacts are present below the water table, therefore, the PMC do not apply.

Generalized Extent of Soil Contamination throughout AOC 5 / RA-3: As discussed above, many of the locations of former floor/trench drains, potential machine pits, equipment locations, and process areas throughout the former southern portion of the building are unknown or unobservable due to soil and debris that is present on top of large portions of the slab. Because of this, multiple borings were advanced throughout AOC 5 to evaluate the potential for unidentified release points.

ETPH was detected in three borings at concentrations well above the I/C DEC within the southcentral portion of AOC 5, in an area where there was no clear indication as to the potential source of the impact. The detected ETPH concentrations exceed the I/C DEC and

GB PMC both set at 2,500 mg/kg. However, analysis by MA EPH indicates compliance with the GB PMC, which supersedes the ETPH results.

The area of ETPH impacted soil includes:

• SB-54 (3.5-5.5’) with ETPH at 17,500 mg/kg

• FSSMW-4 (0-4’) with ETPH at 12,000 mg/kg

• J-13 (4-5’) with ETPH at 5,000 mg/kg

On-Site Groundwaters: Four monitoring wells are present within AOC 5, including FSSMW-4, MW-101, MW-107, & MW-202. In addition, there were two former wells installed in AOC 5 that have since been destroyed (MW-11 & MW-12).

PCBs were detected in a groundwater sample from well MW-202 at 0.84 ug/l, exceeding the

SWPC of 0.5 ug/l. PCBs have not been detected in any other groundwater samples obtained from the site. Note, groundwater turbidity at the time of sampling was slightly elevated at

17.1 nephelometric turbidity units (NTUs), which could be the source of PCBs detected in the groundwater sample.

ETPH was detected at three wells (MW-107, MW-202, & FSSMW-4) at 1,700, 930, and

3,300 ug/l, respectively, which exceed the APS I/C VC and APS SWPC, both set at 250 ug/l.

The presence of ETPH indicates that groundwater has been impacted by releases within AOC

5.

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The groundwater samples from MW-107 and FSSMW-4 were additionally analyzed for MA

EPH, which was detected in the initial sample from well FSSMW-4 at a concentration slightly above the APS RES VC, but below the APS I/C VC and APS SWPC. MA EPH was not detected in subsequent samples obtained five months later, which indicate compliance with the RSRs for petroleum hydrocarbons in groundwater associated with AOC 5 / RA-3.

At well MW-202, the VOC 1,2,4-TCB was detected at 360 ug/l, exceeding the APS RES VC and APS SWPC.