Attachment_I_-_N-RPT-2101230-0_Gibbs_Street-PII-III-Final-2022-05-24.pdf

355 Research Parkway ▪ Meriden, CT 06450 ▪ T (203) 630-1406 ▪ F (203) 630-2615 ▪ www.blcompanies.com

An Employee-Owned Company

PHASE II / III SITE INVESTIGATION

0 Gibbs Street New Haven, Connecticut

Prepared for:

Livable City Initiative City of New Haven

Attention: Mr. Jefferey Moreno 165 Church Street, 3rd Floor

New Haven, CT 06510

Prepared By:

BL Companies, Inc.

355 Research Parkway

Meriden, CT 06450

May 2022 BL Companies Project No. 2101230

Phase II/III Site Investigation 2101230 0 Gibbs Street, New Haven, Connecticut May 2022

This report was prepared by the individuals listed below. Any questions or comments regarding the information provided herein should be directed to these individuals.

Prepared by:

Wesley Johnson Project Scientist II

Reviewed by:

Christy Quagliaroli Senior Project Scientist I

Brian P. Lowry, LEP Project Manager II

TABLE OF CONTENTS

Section Description Page

1.0 INTRODUCTION

1.1 Site Description

1.2 Site History

2.0 ENVIRONMENTAL SETTING

2.1 Geology and Hydrogeology

2.2 Groundwater and Surface Water

3.0 REGULATORY FRAMEWORK

3.1 Connecticut Transfer Act

3.2 Remediation Standard Regulations

3.2.1 Soil Criteria

3.2.2 Groundwater Criteria

3.2.3 Soil Vapor Volatilization Criteria

3.3 Applicable RSR Criteria

4.0 PREVIOUS INVESTIGATIONS……….. ………

5.0 CONCEPTUAL SITE MODEL

5.1 Data Quality Objectives

5.2 AOC Summaries

5.2.1 AOC-1 Former 6,000-Gallon Oil Underground

Storage Tank – Location Unknown

5.2.2 AOC-2 Former Above Ground Storage Tank

5.2.3 AOC-3 Abandoned Underground Storage Tank

5.2.4 AOC-4 Former Fuel oil Tanks, Former Storage, and Office Building

5.2.5 AOC-5 Former 550-Gallon Gasoline Underground Storage Tank

5.2.6 AOC-6 Former Concrete Mixer and Bins with Conveyor Belt ... 16

5.2.7 AOC-7 Site Wide Urban Fill Material

5.2.8 AOC-8 Former Residential Dwellings with Unknown Heating Sources

5.2.9 AOC-9 Former Railroad Spur

5.2.10 AOC-10 Former Transformer Area

6.0 PHASE II/III SITE INVESTIGATION

6.1 Summary of Work and Rationale

6.1.1 Soil Sampling

6.1.2 Groundwater Sampling

6.1.3 Groundwater Elevation Survey

6.2 Analytical Results and Comparison to RSR Criteria

6.2.1 Phase II/III Soil Analytical Results

6.2.2 Phase II/III Groundwater Analytical Results

6.3 Data Quality Assessment/Data Usability Evaluation

7.0 CONCLUSIONS AND RECOMMENDATIONS

7.1 Summary of Findings

7.2 Recommendations

8.0 LIMITATIONS

9.0 REFERENCES

APPENDICES

Appendix A Site Plans Site Location Map Site Plan (SP-01) Site Investigation Plan (SI-01) Groundwater Contour Plan – April 26, 2022 (GW-01)

Appendix B Tables Table 1 – Soil Analytical Data Table 2 – Groundwater Analytical Data

Appendix C Boring Logs and Monitoring Well Diagrams

Appendix D Laboratory Analytical Data Reports

Phase II/III Site Investigation 1 2101230

1.0 INTRODUCTION

BL Companies was retained by the City of New Haven to complete a Phase II/III Site Investigation (SI) at 0 Gibbs Street, New Haven, Connecticut (the “Site”). The location of the Site is depicted on the Site Location Map and the Site layout is depicted on the Site Plan (SP-01) included in Appendix A.

BL Companies reviewed previous environmental reports and completed a Phase I Environmental Site Assessment (ESA) at the Site in March 2021. The Phase I ESA identified several Recognized Environmental Conditions (RECs), as defined by American Society for Testing and Materials (ASTM) 1527-13 and Areas of Concern (AOCs). The Connecticut (CT) Department of Energy and Environmental Protection (CTDEEP) Site Characterization Guidance Document (SCGD) defines AOCs as “locations where hazardous waste and/or hazardous substances (including petroleum products) have been or may have been used, stored, treated, handled, disposed, spilled, and/or released to the environment.”

This Phase II/III SI was conducted to investigate the RECs/AOCs identified during the Phase I ESA in anticipation of the future redevelopment of the Site. The RECs/AOCs were investigated to evaluate the presence or absence of releases of hazardous substances to soil and groundwater from historic Site operations. The investigation was conducted in general accordance with standard and accepted practices and the SCGD.

The results of BL Companies’ Phase II/III SI and the regulatory implications are discussed in this report.

1.1 Site Description

The Site is located at 0 Gibbs Street, New Haven, Connecticut and is owned by the City of New Haven. The Site consists of one irregular-shaped parcel of land totaling approximately 1.15 acres. The Site is currently an asphalt parking lot and is situated in an area of primarily commercial, industrial, and residential land usage.

The northernmost portion of the Site primarily consists of overgrown vegetation. The remainder of the Site consists of asphalt paved areas utilized for parking and storage of various landscaping equipment. Access to the Site is provided via Gibbs Street to the west.

1.2 Site History

Based on a review of available historic records and other information obtained during completion of the March 2021 Phase I ESA, the Site was depicted as a vacant lot in 1886 and was depicted with two residential dwellings by 1901. By 1923, the Site was depicted as a vacant lot, with the exception of Gibbs Street cutting through the central portion of the Site. Sometime between 1921 and 1934, multiple structures were built including one large above ground storage tank (AST) in the northern portion of the Site. By 1941, the Site was labeled as a cement mixing plant owned by C.W. Blakeslee & Sons and a large

Phase II/III Site Investigation 2 2101230 iron AST was depicted in the northern portion of the Site. In addition, a storage building, an office building, and a gas tank were depicted in the central portion of the Site. A concrete mixer and bins with conveyor belt were also depicted in the southern portion of the Site. Furthermore, a railroad siding/spur was depicted along the eastern Site boundary. By 1963, the Site was observed to be vacant and by 1966, the Site was visible as a parking lot. Based on the city directories, the Site was occupied by United Nuclear Corp Naval Products Division in 1978. The exact operations conducted at the Site by the United Nuclear Corp Naval Products Division are unknown. The Site is currently used as a parking lot and storage area for various landscaping equipment.

Phase II/III Site Investigation 3 2101230

2.0 ENVIRONMENTAL SETTING

2.1 Geology and Hydrogeology

Geologically, the Site is located in the Coastal Lowlands Physiographic Province of Connecticut and is underlain by the Triassic aged New Haven Arkose. The New Haven Arkose is characterized as a red, pink, and grey coarse grained, locally conglomeratic, poorly sorted and indurated arkosic sandstone (Rodgers, 1985). Bedrock outcrops were not observed at the Site and bedrock was not encountered during soil boring advancement. Depth to bedrock is deeper than 33 feet below grade surface (’ bgs).

According to the Surficial Soils Map of Connecticut, dated 1992, native soils at the Site are classified as glacial meltwater deposits consisting of sand and gravel overlying sand overlying fines. However, according to the Natural Resources Conservation Service's online Web Soil Survey, soils mantling the Site are classified as Urban Land. Based on observations during soil boring advancement, surficial materials consist of fill material shallow on top of native soils. Fill material was encountered across the entire Site at thicknesses ranging from at 1.5’ to 17’ bgs. Native soils encountered during drilling activities generally consisted of reddish-brown fine to coarse sand with varying amounts of gravel, silt, and clay. Soil lithologies encountered during this Phase II/III SI are described on the boring logs included in Appendix C.

According to the USGS 7.5-Minute Topographic Map of New Haven, Connecticut, and Google Earth, the topography of the Site is relatively flat and it is situated at an elevation of approximately 60 feet above mean sea level. Topography in the vicinity of the Site generally slopes to the south towards the New Haven Harbor, approximately 2.61 miles away from the Site. Based on topography, groundwater in the vicinity of the Site was expected to mimic the surrounding topography and flow to the south. The groundwater flow direction was calculated as part of this Phase II/III SI and flows to the south-southeast.

2.2 Groundwater and Surface Water

The CTDEEP has classified groundwater beneath the Site as GB. The GB classification indicates that groundwater at the Site is presumed not suitable for human consumption without treatment. Groundwaters with a GB classification are designated for uses including industrial process water and cooling waters, and as baseflow for hydraulically connected water bodies. According to the CTDEEP mapping review, the Site is not located within an Aquifer Protection Area.

No surface water bodies were observed on the Site. The nearest surface water body is Beaver Pond, which is located approximately 1,600 feet to the west of the Site. The surface water quality of Beaver Pond is classified as "A”. A Class “A” designation indicates these surface water bodies have designated uses including habitats for fish and other aquatic life, potential drinking water supplies, recreation, navigation, and water supply for industry and agriculture. The New Haven Harbor, which is located

Phase II/III Site Investigation 4 2101230 approximately 2.61 miles downgradient of the Site, is classified as an “SB” water body.

An SB designation indicates these surface water bodies have designated uses including habitat for marine fish and aquatic life and wildlife, commercial shellfish harvesting, recreation, industrial water supply, and navigation.

Phase II/III Site Investigation 5 2101230

3.0 REGULATORY FRAMEWORK

3.1 Connecticut Transfer Act

Connecticut General Statute (CGS) Section 22a-134 is known as the Connecticut Transfer Act (CTA) and regulates the transfer, investigation, and remediation of Hazardous Waste Establishments. An Establishment is defined as any real property at which or any business from which:

• on or after November 19, 1980, there was generated, except as a result of remediation of polluted soil, groundwater or sediment more than 100 kilograms of hazardous waste in any one month;

• hazardous waste generated at a different location was recycled, reclaimed, reused, stored, handled, treated, transported or disposed of;

• the process of dry cleaning was conducted on or after May 1, 1967;

• furniture stripping was conducted on or after May 1, 1967; or

• a vehicle body repair facility was located on or after May 1, 1967.

Effective October 1, 2019, “Establishment” does not include any real property or any business operation from which more than one hundred kilograms of hazardous waste was generated in any one month solely as a result of either:

(i) the one-time generation of hazardous waste in any one month as a result of either the first time such waste was generated or such a one-time generation since the last time a Form I, Form II, Form III or Form IV was required to be submitted; or

(ii) one or more of the following: (I) remediation of polluted soil, groundwater or sediment (II) the removal or abatement of building materials or removal of materials used for maintaining or operating a building; (III) the removal of unused chemicals or materials as a result of the emptying or clearing out of a building, provided such removal is supported by facts reasonably established at the time of such removal; or (IV) the complete cessation of a business operation, provided the waste is removed not later than ninety days after such cessation and such cessation is supported by facts reasonably established at the time of such cessation.

Facilities that are considered Establishments under the CTA are subject to certain reporting requirements to the CTDEEP when a transfer of ownership occurs. One of four filing forms (Form I, II, III, IV) must be submitted to the CTDEEP. The type of filing depends on whether or not there has been investigation of potential release areas at the Site, whether or not there have been regulated compounds released to soil or groundwater, and/or whether or not remediation, if needed has been completed.

Based on the information reviewed by BL Companies during the March 2021 Phase I ESA, the Site does not appear to meet the requirements set forth in the CTA to be considered an Establishment. Therefore, the Site would not likely be subject to the legal

Phase II/III Site Investigation 6 2101230 and technical requirements of the CTA in the event of a transfer. The applicability of the CTA should be confirmed by legal counsel prior to any qualifying ownership transfer.

3.2 Remediation Standard Regulations

The Remediation Standard Regulations (RSRs) are outlined in Sections 22a-133k-1 through 3 of the Regulations of the Connecticut State Agencies (RCSA) that were promulgated in January 1996 and subsequently amended in June 2013 and again in February 2021. The RSRs specify the allowable levels of regulated compounds in soil and groundwater that correspond with areas with groundwater classified as either GA (presumed suitable for drinking water purposes without treatment) or GB (presumed unsuitable for drinking without treatment).

The RSRs apply to sites that are remediated pursuant to Chapter 445, Chapter 446k, or section 22a-208a(c)(2) of the Connecticut General Statutes. Chapter 445 of the Connecticut General Statutes pertains to certain hazardous waste facilities, sites undergoing remediation under CTDEEP’s Urban sites remedial action program, sites that are subject to CTDEEP’s voluntary site remediation programs, and “establishments” as defined under section 22a-134 of the Connecticut General Statutes. Chapter 446k of the Connecticut General Statutes pertains to sites that are undergoing remediation pursuant to an enforcement action issued by the CTDEEP, sites with regulated underground storage tanks (USTs), sites with oil and chemical spills, sites where polychlorinated biphenyls (PCBs) have been released, and regional water pollution control facilities.

Section 22a-208a(c)(2) of the Connecticut General Statutes pertains to permitted solid waste disposal facilities.

3.2.1 Soil Criteria

The RSRs define two criteria that apply to polluted soil: the Direct Exposure Criteria (DEC) and the Pollutant Mobility Criteria (PMC). Soil at sites that are subject to the RSRs must be remediated to concentrations that are equal to or less than the DEC and PMC or the background concentrations in soil. The DEC define the maximum levels of regulated compounds allowed in soil to a depth of 15 feet bgs without posing a threat due to direct human exposure. The PMC set the maximum level of regulated compounds allowed in soil without posing a threat to groundwater quality. Each criteria type is further divided into two categories; the DEC is based upon site usage (i.e., residential or industrial/commercial use), while the PMC is based on the groundwater classification (i.e., GA/GAA or GB). The Site is located in an area with a GB groundwater classification;

therefore, the soil must meet the GB PMC.

Demonstration of soil meeting background concentrations (in lieu of demonstrating compliance with DEC and PMC) requires a representative sampling program used to characterize the background concentration for soil that is:

o Of similar texture and composition, Phase II/III Site Investigation 7 2101230 o Collected from the nearest location practicable outside the release area;

and, o Not affected by another discrete release of the same substance or having an effect on the concentrations of the same substance for which a background concentration is determined and either, all analytical results in the release area are equal to or less than the background concentration, or a statistical comparison of the background concentrations to the concentrations in the release area results in significant similarity.

The residential direct exposure criteria (RES DEC) must be met if a site is to be used for current or future residential purposes and is the default/baseline DEC criteria required by the RSRs. The CTDEEP and the RSRs define “residential activity” to mean any activity at: (A) a place intended for people to live, including but not limited to, a residence, dwelling, house, apartment, condominium, nursing home, or dormitory; (B) a pre-school, primary school, secondary school, day care center, playground, or outdoor recreational area; or (C) a hospital, solely for the purposes of compliance with volatilization criteria.

If a site or property is not currently used or planned to be used in the future for residential purposes, then the industrial/commercial direct exposure criteria (I/C DEC) may be applied if an Environmental Use Restriction (EUR) is filed in the land records for the Site.

The EUR, which consists of either an Environmental Land Use Restriction (ELUR) or a Notice of Activity Use Limitation (NAUL), places certain usage limitations on a property, which includes but is not limited to, an industrial or commercial use restriction, prohibition of soil exposure or disturbance, or a no-build restriction. A NAUL can only be used in circumstances that are listed in section 22a-133k-1(e)(1)(B) of the RSRs. The current use of the Site meets the definition of industrial/commercial.

3.2.2 Groundwater Criteria

The RSRs include three criteria that apply to groundwater: the groundwater protection criteria (GWPC), the surface water protection criteria (SWPC), and the groundwater volatilization criteria (GWVC). Groundwater in GA areas typically must meet background concentrations in accordance with the RSRs. However, an RSR alternative indicates that groundwater in GA areas can meet the GWPC if a public water supply is available within 200 feet of the site where the release to groundwater is located, adjacent sites, and sites within the aerial extent of the groundwater plume. In addition, the GWPC can be applied in lieu to demonstrating compliance with background; provided, o The plume is not within an aquifer protection area;

o Prior to remediation of soil or groundwater remediation, the plume is a diminishing state;

o Each substance in groundwater is remediated to GWPC and reduction of concentrations to background cannot be achieved.

Phase II/III Site Investigation 8 2101230

The GWPC define the maximum levels of regulated compounds allowed in groundwater for protection of the groundwater as a potable water source. The Site is located in a GB groundwater classification area therefore, the GWPC does not apply to the Site.

The SWPC apply to impacted groundwater that is discharging to a surface water body, including, streams, rivers, ponds, lakes, and Long Island Sound. The SWPC specifies the levels of compounds allowable in groundwater just prior to discharging into surface water. One standard has been set for groundwater that discharges to surface water, regardless of the classification of such surface water. One method of demonstrating compliance with the SWPC is established at the point at which the groundwater plume discharges to the surface water body. For properties that do not have surface water, the point of compliance for the SWPC is typically considered to be the downgradient property boundary. The RSRs also contain additional options for demonstrating compliance with the SWPC, which includes but is not limited to, requests for an alternative SWPC based on available dilution in the receiving water body.

The GWVC sets the allowable levels of volatile organic compounds (VOCs) within certain distances of a building (within 10 feet bgs or lowest portion of a building for aromatic/petroleum VOCs and within 30 feet bgs or lowest portion of a building for chlorinated or non-petroleum VOCs). The GWVC are designed to protect humans from exposure to VOCs present in shallow groundwater that may migrate as vapors into an overlying building interior. The GWVC is dependent on a property’s usage, with residential GWVC (RES GWVC) and industrial/commercial GWVC (I/C GWVC) established in the RSRs. The RES GWVC is more stringent and the default/baseline GWVC criteria required by the RSRs. The I/C GWVC may be applied if a site is used for industrial/commercial purposes and an EUR is recorded for the property. Compliance with the GWVC may not be required if monitoring of soil vapor above the water table or indoor air quality demonstrates that there is no exposure hazard.

3.2.3 Soil Vapor Volatilization Criteria

The soil vapor volatilization criteria (SVVC) were developed to identify situations where VOCs present in soil vapor have the potential to migrate into an overlying building and pose a risk to human health from the inhalation of the contaminants by occupants of the building. The SVVC may be used as an alternative for assessing potential migration of VOCs into an overlying building in lieu of assessing groundwater relative to the GWVC.

Residential (RES) and industrial/commercial (I/C) SVVC have been established, with the Res SVVC being more stringent, and the I/C SVVC requiring the use of an EUR.

3.3 Applicable RSR Criteria

Because the Site is located in a GB groundwater classification area, the GB PMC apply to the soil that is present above the seasonal high-water table. In the absence of an EUR restricting the Site from residential use, the RES DEC apply to soil that is present within 15 feet bgs at the Site.

The SWPC and RES GWVC apply to the groundwater at the Site.

Phase II/III Site Investigation 9 2101230

4.0 PREVIOUS INVESTIGATIONS

Phase II Environmental Site Assessment, 0 Gibbs Street, New Haven, Connecticut, prepared by Diversified Technology Consultants (DTC), prepared for Regional Growth Partnership, April 6, 2004.

The Scope of Work for this previous investigation consisted of the completion of a ground penetrating radar (GPR) survey of the Site, soil borings, test pits, and collection of soil and groundwater samples for analysis.

DTC reviewed and summarized a Phase I ESA prepared by Catalyst Environmental Consulting, Inc. (Catalyst) in September 2003. At the time of the report, the Site was described as a 1.15-acre parcel of land that was vacant and paved with bituminous concrete. According to Catalyst, the Site was developed by between 1890 and 1901 with two dwellings in the central portion of the Site. Between 1932 and 1961, a concrete mixing plant occupied the Site and consisted of an office building, fuel oil house and plant. At least one gasoline UST and one large tank were noted. Catalyst reviewed a 1940 Site plan, which depicted a concrete plant in the southern portion of the Site and consisted of an office building, 1,000-gallon gasoline UST, and a fuel oil house containing eight 8,000-gallon tanks. A soft coal storage area was depicted in the southwestern portion of the Site and a railroad spur was depicted along the eastern Site boundary. A Site Plan included in the DTC report depicts an abandoned tank in the northern portion of the Site. The locations of former fuel oil tanks, former office and identified UST are depicted in the central portion of the Site. A former concrete mixer and bins with conveyor belt are depicted in the southeastern portion of the Site.

From 1965 through 1974, the Site was used as a paved parking lot for material storage.

According to the Catalyst report, a 6,000-gallon oil tank was removed by Clean Harbors in June 2000. No additional information was found related to the tank.

As part of the 2004 Phase II DTC oversaw a GPR survey to locate potential USTs at the Site. A subsurface anomaly located east of the Gibbs Street entrance, described as an approximately 6-foot by 4-foot square, was identified as a potential 550-gallon UST.

DTC oversaw the advancement of two soil borings and nine test pits at the Site. The test pits were dug to approximate depths ranging from 6 to 8’ bgs. A test pit was completed at the anomaly and an approximately 550-gallon steel UST and piping was encountered.

No indications of a release were observed. Groundwater samples were collected from each of the soil borings using temporary stainless steel well points and bailers. A sheen and odor, "indicative of weathered No. 2 fuel oil", was observed in the groundwater sample collected from boring B-2 around 25-28 feet below grade. DTC concluded the sheen and odor may be associated with a release from off-Site to the east.

Soil and/or groundwater samples were analyzed for VOCs, polynuclear aromatic hydrocarbons (PAHs), extractable total petroleum hydrocarbons (ETPH), Resource Conservation and Recovery Act (RCRA) 8 metals, Synthetic Precipitation and Leaching

Phase II/III Site Investigation 10 2101230

Procedure (SPLP) lead and/or arsenic, SPLP PAHs, and PCBs. Based on the analytical results, DTC noted the following:

• Aromatic VOCs were detected in two soil samples below regulatory criteria, which DTC opined was indicative of weathered gasoline.

• Chlorinated VOCs were detected in seven soil samples below regulatory criteria, which DTC believed may be attributed to impacted fill materials or minor Site wide spillage.

• PAHs were detected in 16 soil samples, several of which exceeded regulatory criteria and appear to be related to ash and slag in urban fill material.

• Leachable PAHs, analyzed in two samples, were not detected.

• ETPH was detected in 14 soil samples, 13 of which were collected from urban fill material and were below regulatory criteria. The remaining sample exceeded regulatory criteria and DTC concluded this may be due to a potential release from a historic AST.

• Total metals including arsenic and lead were detected above regulatory criteria.

Total beryllium was detected above laboratory reporting limits and below regulatory criteria.

• Leachable lead was detected in each sample analyzed and was detected above regulatory criteria in two samples. Leachable arsenic was not detected.

• PCBs were not detected in the soil samples analyzed; however, a test pit proposed near a former transformer was relocated due the presence of a gas line.

• Low VOC concentrations were detected in the groundwater samples below regulatory criteria.

Based on the findings of their Phase II assessment, DTC concluded and/or recommended the following:

• Removal of the approximately 550-gallon UST and collection of closure samples.

• Urban fill is present throughout the Site with an average thickness of 4.4 feet, with some pockets extending to 11’ bgs. Fill materials consist of dense black ash, yellow/orange slag/cinders, concrete and sand. Soil samples collected from the fill material contained concentrations of PAHs, lead, and arsenic exceeding regulatory criteria. DTC concluded the native soil below the fill "does not appear to be impacted with significant concentrations of regulated compounds...and impacts appear to be limited to the urban fill."

Phase II/III Site Investigation 11 2101230

• Soils impacted with ETPH, and lead, were identified in the northern portion of the Site. DTC recommended a Phase III ESA be conducted to delineate the extent of ETPH and lead impact to soil. Upon completion of the Phase III ESA, a Remedial Action Plan (RAP) should be prepared for the Site. DTC concluded that based on the current information, the likely approach to remediate the ETPH and lead impacts at the Site would include excavation. DTC also concluded that the most cost-effective approach to address urban fill would be to render the fill inaccessible to human contact.

• DTC concluded that groundwater does not appear to be significantly impacted, but stated additional sampling may be necessary to support this finding.

Phase I Environmental Site Assessment, 0 Gibbs Street, New Haven, Connecticut, prepared by BL Companies, prepared for City of New Haven – Livable City Initiative, March 18, 2021.

BL Companies completed a Phase I ESA at the Site in March 2021. Relevant findings relating the current Site layout at the time of the Phase I and the Site history are discussed in Section 1.1 Site Description and Section 1.2 Site History above.

BL Companies’ Phase I ESA included a review of the 2004 Phase II SI completed by DTC. DTC had recommended additional investigation and potential remediation be completed at the Site. However, no evidence of additional investigation or remediation was discovered during completion of BL Companies’ Phase I ESA.

The Phase I ESA did not reveal any evidence of historical recognized environmental conditions (HRECs) or Business Environmental Risks (BERs)/De Minimis Conditions.

The Phase I ESA did reveal the following RECs in connection with Site:

• Former 6,000-Gallon UST: According to the DTC Phase II ESA, a 6,000-gallon oil tank was removed in June 2000. No closure documents were found. The Catalyst Phase I ESA, reviewed by DTC, stated it was unclear if this UST was located on the Site or on the abutting property.

• Former AST: An iron AST was once located within the northern portion of the Site.

• Abandoned Tank: According to the DTC Site Plan, an abandoned tank was depicted in the northernmost portion of the Site.

• Former Fuel Oil Tanks, Former Storage and Office Buildings: Based on review of the historical documents and the DTC Site Plan, a former storage building containing eight 8,000-gallon fuel oil tanks and a former office building were depicted in the central portion of the Site. Samples collected from this area indicated the presence of ETPH and total lead above regulatory criteria.

Phase II/III Site Investigation 12 2101230

• Gas Tank: A gas tank was depicted on the 1951 Sanborn map in the central portion of the Site. An abandoned approximately 550-gallon UST was found during GPR and test pit activities by DTC in 2004. DTC recommended that this UST be removed; however, it is unknown if the tank was removed, or if closure samples were collected.

• Former Concrete Mixer and Bins with Conveyor Belt: A former concrete mixer with bins and conveyor belt were depicted in the southeastern portion of the Site.

Samples collected from this area indicated the presence of arsenic above regulatory criteria. Test pits to the north of this area indicated the presence of total and SPLP lead as well as PAHs above regulatory criteria.

• Urban Fill: Urban fill was identified throughout the Site to an average depth of 4 feet below grade, and up to 11 feet below grade. Fill was observed to consist of black ash, slag/cinders, concrete, sand and other miscellaneous debris. Soil samples from the urban fill layer indicated the presence of PAHs, lead, and arsenic above regulatory criteria.

• Former Dwellings with Unknown Heating Sources: Based on review of the

1901 Sanborn map, two dwellings were depicted in the west-central portion of the Site. The heating sources of the former dwellings are unknown.

• Railroad Spur: A railroad spur was depicted along the eastern Site boundary from approximately 1923 through 1973 and extended off-Site to the north and south.

• Soft Coal Storage Area: According to a 1940 Site Plan reviewed by Catalyst, a soft coal storage area was depicted on the southeastern portion of the Site.

• Past Site Usage: Based on review of the city directories, the Site may have been occupied by United Nuclear Corp Naval Products Division in 1978. The use of the Site by this company is unknown.

Based on the findings of the Phase I ESA, BL Companies recommended the following:

• A Phase II/III Investigation should be completed to further evaluate the RECs identified during this ESA. The purpose of the Phase II/III investigation would be to investigate areas that were not previously investigated, as well as confirm the extent of environmental impacts for redevelopment planning. At a minimum, the Phase II/III should include a GPR survey to locate subsurface anomalies, and the installation of additional soil borings/test pits and groundwater monitoring wells at strategic locations. The previously existing wells should be evaluated, and if viable, redeveloped and sampled. Based on the results of the Phase II/III, additional investigation may be warranted including the development of a RAP to support the proposed reuse and development.

Phase II/III Site Investigation 13 2101230

5.0 CONCEPTUAL SITE MODEL

BL Companies has prepared a Conceptual Site Model (CSM) for the Site based upon the geology, hydrogeology, and the current and historical use of the Site, as documented in BL Companies’ Phase I ESA, and supplemented with the observations made during this investigation. A CSM is a description of the environmental system at a Site that provides a framework for communicating the rationale for the Site investigation process. The CSM describes all potential release areas as well as release mechanisms, contaminant fate and transport characteristics, and potential migration pathways at the Site. BL Companies prepared a preliminary CSM as described below.

The preliminary CSM was used to develop an investigative approach to characterize each AOC in accordance with the CTDEEP SCGD and RSRs. The goal of this Phase II/III SI was to determine the presence or absence of a release of constituents of concern (COCs) in soil and/or groundwater at the Site. Soil borings were advanced and monitoring wells were installed to collect soil and groundwater samples for analysis for the presence of specific COCs.

Based on the information, BL Companies identified a total of ten (10) AOCs at the Site, which included the following:

• AOC-1: Former 6,000-Gallon Oil Underground Storage Tank – Location Unknown

• AOC-2: Former Above Ground Storage Tank

• AOC-3: Abandoned Underground Storage Tank

• AOC-4: Former Fuel Oil Tanks, Former Storage, and Office Buildings

• AOC-5: Former 550-Gallon Gasoline Underground Storage Tank

• AOC-6: Former Concrete Mixer and Bins with Conveyor Belt

• AOC-7: Site Wide Urban Fill Material

• AOC-8: Former Residential Dwellings with Unknown Heating Sources

• AOC-9: Former Railroad Spur

• AOC-10: Former Transformer Area

5.1 Data Quality Objectives

Development, revision, and validation of the CSM processes are dependent upon the complexity of the site conditions and the project-specific data quality objectives (DQOs)

Phase II/III Site Investigation 14 2101230 that are established to adequately characterize the site. The DQOs for the site characterization process are developed to ensure data of sufficient quality and quantity are collected to support decisions and conclusions made during site characterization and to aid in the ultimate validation of the CSM.

DQOs are statements that clarify objectives, define the appropriate type and quantity of data to be collected, establish the appropriate conditions for data collection, and specify acceptable levels of error and laboratory reporting levels that will be used as the basis for establishing the quantity and quality of the data needed to support decisions made based upon the use of that data. The DQO process used on this project was developed to help guide data collection activities, to develop a defensible rationale for collecting samples and to ensure that the data used in the decision-making process were appropriate for the intended use.

5.2 AOC Summaries

This section provides summaries of the nature of the AOCs which have been the subject of the Phase II/III activities conducted by BL Companies, as well as descriptions of the potential release mechanisms, potential migration pathways, and COCs that are associated with each AOC. These aspects of the CSM were used in guiding implementation of the Phase II/III activities described in Section 6.0 below.

Each of the AOCs are shown on the Site Plan (SP-01) and the Site Investigation Plan (SI-01) included in Appendix A.

5.2.1 AOC-1: Former 6,000-Gallon Oil Underground Storage Tank – Location Unknown

According to the DTC Phase II ESA, a 6,000-gallon oil UST was closed and removed from the Site in June 2000. The Catalyst Phase I ESA, which was summarized in the DTC Phase II report, stated that it was unclear if the UST was located on the Site or abutting the property. The Site plan included in the DTC Phase II report did not include any specific call out for a former 6,000-gallon UST. No closure documentation was found during completion of the Catalyst Phase I ESA or the BL Companies Phase I ESA. In addition, this tank/tank grave was not identified during BL Companies’ Phase II/III activities.

Potential Release Mechanisms: Structural failures from the UST materials which would result in spills of petroleum products directly to subsurface soils.

Potential Migration Pathways: Releases to subsurface soils surrounding the UST, downward migration through subsurface soils toward the water table, and potential migration with groundwater.

Constituents of Concern: ETPH, PAHs, and VOCs.

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5.2.2 AOC-2: Former Above Ground Storage Tank

BL Companies’ Phase I ESA identified a large iron AST which was depicted in the northern portion of the Site on a 1951 historical Sanborn map. By 1973, this tank was no longer depicted. Additional information regarding the contents, use, and closure was not able to be reviewed as part of BL Companies’ Phase I ESA or Phase II/III SI.

Potential Release Mechanisms: Structural failures from the AST materials which would result in spills of petroleum products directly to the surface.

Potential Migration Pathways: Releases to surface materials surrounding the AST, then downward through asphalt or concrete, if present, further migration downward through subsurface soils toward the water table, and potential migration with groundwater.

Constituents of Concern: ETPH, PAHs, and VOCs.

5.2.3 AOC-3: Abandoned Underground Storage Tank

An abandoned tank is depicted on the northernmost property border of the Site on the DTC Phase II Site plan. However, DTC does not specifically discuss any abandoned tank at this location, or at the Site, in their Phase II report. No other information is known at this time regarding the size, contents, or current status of this “abandoned” tank. It is possible that the abandoned tank depicted on the DTC Site plan may in fact be referring to the tank identified and discussed as AOC-1.

Potential Release Mechanisms: Structural failures from the UST materials which would result in spills of petroleum products directly to subsurface soils.

Potential Migration Pathways: Releases to subsurface soils surrounding the UST, downward migration through subsurface soils toward the water table, and potential migration with groundwater.

Constituents of Concern: ETPH, PAHs, and VOCs.

5.2.4 AOC-4: Former Fuel Oil Tanks, Former Storage, and Office Building

Based on review of the historical documents and the DTC Phase II report/Site Plan, a former small office building and larger fuel oil house containing eight 8,000-gallon fuel oil tanks were located in the northcentral portion of the Site. Samples collected from this area during the DTC Phase II indicated the presence of ETPH and total lead above regulatory criteria. Additional information regarding the ASTs, closure dates, or any potential releases, are not known at this time.

Potential Release Mechanisms: Structural failures from the AST materials which would result in spills of petroleum products directly to the surface.

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Potential Migration Pathways: Releases to surface materials surrounding the AST, then downward through asphalt or concrete, if present, then further migration downward through subsurface soils toward the water table, and potential migration with groundwater.

Constituents of Concern: ETPH, PAHs, and VOCs.

5.2.5 AOC-5: Former 550-Gallon Gasoline Underground Storage Tank

A gas tank was depicted in the central portion of the Site on a 1951 Sanborn map reviewed during BL Companies’ Phase I ESA. Historical Site Plans reviewed during the Catalyst Phase I ESA, and summarized in the DTC Phase II report, depicted a 1,000-gallon gasoline UST in the northcentral portion of the Site in the vicinity of the small office building discussed in AOC-4. A GPR survey was completed by DTC during their Phase II SI and identified a 6-foot by 4-foot anomaly approximately 76 feet east of the Gibbs Street entrance. A test pit was completed by DTC adjacent to this anomaly confirmed the presence of a 550-gallon UST with associated piping. The report notes that the tank was located at a depth of 3 to 3.5’ bgs and that no indications of a release from the UST were observed during the excavation. DTC recommended this tank be removed; however, it is unknown if the tank was properly closed and actually removed. This tank/tank grave was not identified during BL Companies’ Phase II/III SI activities, indicating the tank may have been removed from the Site sometime between 2004 and 2022. However, closure documentation, or information regarding closure samples, was not available for review during the completion of BL Companies’ Phase I ESA.

Potential Release Mechanisms: Structural failures from the UST materials which would result in spills of petroleum products directly to subsurface soils.

Potential Migration Pathways: Releases to subsurface soils surrounding the UST, downward migration through subsurface soils toward the water table, and potential migration with groundwater.

Constituents of Concern: VOCs and lead.

5.2.6 AOC-6: Former Concrete Mixer and Bins with Conveyor Belt

Based on information reviewed during BL Companies’ Phase I ESA, the Site was formerly occupied by a cement mixing plant owned by C.W. Blakeslee & Sons. According to the DTC Phase II report, the mixing plant occupied the Site from 1932 to 1961. Based on the DTC Site Plan, the former concrete mixer with bins and conveyor belt were located in the southeastern portion of the Site. Samples collected from this area during DTC’s Phase II SI indicated the presence of arsenic above regulatory criteria. Test pits completed to the north of this area by DTC indicated the presence of total and SPLP lead as well as PAHs above regulatory criteria.

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Potential Release Mechanisms: Failure of equipment resulting in spills of petroleum products and/or hazardous substances used during historic operations.

Potential Migration Pathways: Releases to surface materials, then downward through asphalt or concrete if present, then further migration downward through subsurface soils toward the water table, and potential migration with groundwater.

Constituents of Concern: VOCs, ETPH, PAHs, metals, and PCBs.

5.2.7 AOC-7: Site Wide Urban Fill Material

Urban fill material was identified at the Site by DTC during their 2004 Phase II SI. Based on their drilling and test pitting activities, DTC concluded that urban fill material was present throughout the Site at an average thickness of 4 feet with areas up to 11 feet thick. DTC reported that fill material consisted of black ash, slag/cinders, concrete, sand, and other miscellaneous debris. Soil samples collected from the fill material by DTC indicated the presence of PAHs, lead, and arsenic at concentrations exceeding the regulatory criteria.

Potential Release Mechanisms: Placement of polluted fill material at the Site.

Potential Migration Pathways: Leaching of constituents of concern from polluted fill material downward toward the water table, and potential migration with groundwater.

Constituents of Concern: VOCs, ETPH, PAHs, metals, and PCBs.

5.2.8 AOC-8: Former Residential Dwellings with Unknown Heating Sources

Based on review of the 1901 Sanborn map of the Site, two residential dwellings were previously located in the west-central portion of the Site. The heating sources of the two dwellings are unknown. The use of coal or heating fuel at these dwellings cannot be precluded at this time.

Potential Release Mechanisms: Potential failure of petroleum storage containers releasing petroleum products.

Potential Migration Pathways: Releases to surface, or subsurface, materials surrounding the storage containers, then downward migration through subsurface soils toward the water table, and potential migration with groundwater.

Constituents of Concern: ETPH, PAHs, and VOCs.

5.2.9 AOC-9: Former Railroad Spur

Based on review of the historical information during BL Companies’ Phase I ESA, a railroad spur was formerly located along the eastern Site boundary from at least 1923

Phase II/III Site Investigation 18 2101230 through 1973. The railroad spur extended off-Site to the north and south. The purpose/ use of the railroad and/or what substances may have been transported on the railroad are unknown at this time. According to DTC, the Catalyst Phase I ESA discussed a 1988 CT Department of Environmental Protection (DEP) complaint for the Site. Reportedly, employees of Olin Brass Mills emptied approximately 100 55-gallon drums of waste oils, solvents, chlorine, and other unknown chemicals along the railroad tracks. The exact location of this dumping is not known. Further information regarding this was not available for review.

Potential Release Mechanisms: Potential failure of petroleum/hazardous substance storage containers during loading, unloading, or transport. Dumping of 55-gallon drums releasing various petroleum products and hazardous substances.

Potential Migration Pathways: Releases to surface materials, then downward migration through subsurface soils toward the water table, and potential migration with groundwater.

Constituents of Concern: VOCs, ETPH, PAHs, Metals, and PCBs.

5.2.10 AOC-10: Former Transformer Area

According to the 1951 historical Sanborn map, two transformers were located in the southwestern corner of the Site. In addition, the transformers were identified on the DTC 2004 Site Plan as former transformers. DTC proposed to complete a test pit in the vicinity of the former transformer area during their Phase II SI activities. However, the test pit was not able to be completed at that location due to the presence of a gas line. No information regarding the PCB content of the former transformers is known. However, based on the reported age of the former units, the potential presence of PCBs cannot be precluded.

Potential Release Mechanisms: Potential release of dielectric fluids from the former transformer.

Potential Migration Pathways: Releases to surface materials and downward through subsurface soils to the water table.

Constituents of Concern: ETPH and PCBs

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6.0 PHASE II/III SITE INVESTIGATION

The following is a discussion of the investigation approach conducted by BL Companies as part of the Phase II/III SI completed at the Site in April of 2022. The field-sampling program described herein was designed to fulfill the DQOs of determining the presence or absence of COCs in soil and/or groundwater that may have resulted from releases of petroleum products and/or hazardous substances from the identified AOCs at the Site.

6.1 Summary of Work and Rationale

BL Companies mobilized a Subsite 830/Mala HDR ground penetrating radar (GPR) to the Site on April 14, 2022. The survey was completed in order to look for evidence of current/former USTs and to clear proposed drilling locations of underground utilities using electromagnetic induction (EMI) and GPR. No evidence of USTs or anomalies was identified during completion of the GPR survey. Utilities were identified and drilling locations were cleared or adjusted, as necessary. BL Companies mobilized a

Geoprobe 6610DT drill rig, operated by SoilTesting, Inc. (SoilTesting), on April 18, 2022, to advance soil borings at the Site. BL Companies mobilized a Diedrich D-120 hollow stem auger (HSA) drill rig, operated by SoilTesting on April 19, 2022, to install monitoring wells at the Site.

A total of 12 soil borings, identified as SB-1 through SB-12, were completed at the Site.

Following completion of soil boring advancement, SoilTesting completed soil borings SB- 1, SB-3, SB-7, and SB-9 as monitoring wells BLMW-1 through BLMW-4, respectively.

Monitoring well BLMW-1 had to be offset from SB-1 slightly due to access issues relating to the larger HSA drill rig. The location of the soil borings and groundwater monitoring wells are depicted on the Site Investigation Plan (SI-01) included in Appendix A. Soil borings and monitoring wells completed during the Phase II SI were located in the following areas:

• Southernmost portion of the Site: Two soil borings, SB-1 and SB-2, were installed within the southernmost portion of the Site. In addition, monitoring well BLMW-1 was installed adjacent to soil boring SB-1. Soil borings were completed, and monitoring wells were installed, in order to assess the current soil and groundwater conditions within the southern portion of the Site which may have been impacted by releases from upgradient AOCs and/or by impacted urban fill material.

• Southcentral portion of the Site: Four soil borings, SB-3 through SB-6, were completed within the southcentral portion of the Site. In addition, monitoring well BLMW-2 was installed at the SB-3 soil boring location. Soil borings were completed, and monitoring wells were installed in order to assess the current soil and groundwater conditions within the southcentral portion of the Site which may have been impacted by releases from AOC-6, AOC-8, AOC-9, other upgradient AOCs, or by impacted urban fill material.

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• Northcentral portion of the Site: Three soil borings, SB-7 through SB-9, were installed within the northcentral portion of the Site. In addition, monitoring wells BLMW-3 and BLMW-4 were installed at boring locations SB-7 and SB-9, respectively. Soil borings were completed, and monitoring wells were installed, in order to assess the current soil and groundwater conditions within the northcentral portion of the Site which may have been impacted by releases from AOC-2, AOC- 4, AOC-5, other upgradient AOCs, or by impacted urban fill material.

• Northernmost portion of the Site: Three soil borings, SB-10 through SB-12, were installed within the northernmost portion of the Site.