Attachment 6- Kinneytown CT - SupplementalPhaseII_v1.pdf

Site-Specific Quality Assurance Project Plan Kinneytown Dam, Seymour, Connecticut Supplemental Phase II – Environmental Site Assessment

June 2025 Prepared for:

Environmental Protection Agency Targeted Brownfields Assessment Program EPA New England, Region 1 5 Post Office Square - Suite 100 Boston, MA 02109-3912

Naugatuck Valley Council of Governments and Connecticut Brownfield Land Bank 49 Leavenworth Street, Waterbury CT, 06702

Kinneytown Dam, Supplemental Phase II ESA Site-Specific Quality Assurance Project Plan i

Contents

1.0 Title and Approval Page

2.0 Project Organization & Key Personnel

3.0 Problem Definition & Project Quality Objectives

3.1 Problem Definition

3.2 Project Site Description

3.2.1 Site History

3.2.2 Current Ownership and Use

3.2.3 Proposed Development

3.3 Contaminants of Concern

3.4 Tasks to be Performed

3.5 Sampling Locations and Rationale

3.6 Sampling Media and Parameters

3.7 Regulatory Standards and Guidance Values

3.8 Decision Statement

4.0 Project Timeline

5.0 Sampling and Analytical Requirements

5.1 Sample Summary

5.2 Field Measurements

5.3 Sample Analysis

6.0 Project Specific SOP References

7.0 Field Equipment Calibration & Corrective Action

8.0 Laboratory Equipment Calibration & Corrective Action

9.0 Sampling Handling and Custody Requirements

10.0 Field and Analytical Laboratory Quality Control Summary

11.0 Data Management & Project Reports

12.0 Assessment and Oversight

13.0 Data Review

14.0 References

Site-Specific Quality Assurance Project Plan ii

List of Tables Table 1: Key Personnel

Table 2: Contaminants of Concern

Table 3: Categories of Screening Values

Table 4: Project Timeline

Table 5: Sample Summary

Table 6: Laboratory Analytical Summary

Table 7: Alpha Analytical Laboratory SOP References

Table 8: Project Specific SOP References

Table 9: Field Quality Control Samples

List of Figures Figure 1: Site Location

Figure 2: Topographic Map

Figure 3: Site Layout

Figure 4: Proposed Sampling Locations – Upper Impoundment

Figure 5: Proposed Sampling Locations – Downstream Background

Figure 6: Proposed Sampling Locations – Upstream Background

Appendices Appendix A: Analyte Lists

Site-Specific Quality Assurance Project Plan iii

Acronyms and Abbreviations ACM asbestos containing materials AHERA Asbestos Hazard Emergency Response Act

BTAG

Bss

Biological Technical Assistance Group below sediment surface

C&D construction and demolition CoC contaminant of concern CT DEEP Connecticut Department of Energy and Environmental Protection

CT-RCS

CT-WQS

CT Residential Direct Exposure Criteria for soil CT Water Quality Standards

EPA United States Environmental Protection Agency

ESA

ESV

environmental site assessment ecological screening values

ETPH extractable total petroleum hydrocarbons

ft. bgs feet below ground surface FERC Federal Energy Regulatory Commission LBP lead-based paint

GPR

IDW

ground penetrating radar Investigation derived waste

NOAA National Oceanic and Atmospheric Administration NVCOG Naugatuck Valley Council of Government PCB polychlorinated biphenyl PEC probable effect concentration PID photoionization detector PFAS per- and polyfluoroalkyl substances QA quality assurance

QAPP

REC

RSV

Quality Assurance Project Plan recognized environmental condition refinement screening values

SOP standard operating procedure SQG sediment quality guideline SQuiRTs screening quick reference tables SSQAPP Site-Specific Quality Assurance Project Plan SVOC semivolatile organic compound TBA targeted brownfields assessment TEC freshwater threshold effect concentration U.S. DOT United States Department of Transportation

USACE

VOC

United States Army Corps of Engineers volatile organic compound

Volpe U.S. DOT Volpe National Transportation Systems Center

Site-Specific Quality Assurance Project Plan 1

1.0 Title and Approval Page

Project Name: Kinneytown Dam, Seymour, CT Supplemental Phase II ESA

Project Location: 677 South Main Street, Seymour, CT, Parcel ID: 11-03-35-0; 769 Derby Avenue, Seymour, CT, Parcel ID: 12-04-24; 0 Hotchkiss Terrace, Ansonia, CT, Parcel ID: 036- 0001-0003

Document Title: Site-Specific Quality Assurance Project Plan

Lead Organization: Untied States Environmental Protection Agency Region 1

Interagency Agreement Number: VXBS

Preparer: U.S. DOT Volpe National Transportation Systems Center

Preparer address and contact info: 220 Binney Street, Cambridge, MA 02142, 617-494-3974

Date: 6/6/25 Rev: 1.0

This Site-Specific Quality Assurance Project Plan (SSQAPP) supplements the U.S. DOT Volpe Brownfields Generic Quality Assurance Project Plan (# 23063).

Volpe Program Manager: Michelle Heimgartner, Senior Environmental Engineer

Volpe QA Officer: Christopher Zevitas, Sc.D., Senior Environmental Engineer

EPA QA Reviewer: Emily Ambeliotis

EPA Brownfields Program Officer: James Byrne

Site-Specific Quality Assurance Project Plan 2

2.0 Project Organization & Key Personnel

In support of the United States Environmental Protection Agency (EPA) Region 1 Targeted Brownfields Assessment (TBA) Program, the United States Department of Transportation Volpe National Transportation Systems Center (Volpe) will perform a supplemental Phase II environmental site assessment (ESA) for the Kinneytown Dam Project in Seymour, CT. The Volpe Project Team includes the Volpe Program Manager, Project Implementer, and Quality Assurance (QA) Officer. The project team may be supplemented with additional Volpe scientists and engineers as needed. The project organization, lines of authority, roles, and responsibilities and contact information are included in Table 1 and depicted in the graphic below. Project roles and organization are subject to change.

Table 1: Key Personnel

Role Name Title Phone EPA Project Officer James Byrne Brownfield Program Officer 617-918-1389 EPA QA Officer Emily Ambeliotis EPA QA Officer 617-918-8348 Grantee Contact Ricardo Rodriquez NVCOG Brownfield Project

Manager 202-982-0797

Volpe Program Manager Michelle Heimgartner Senior Environmental Engineer 617-494-2098 Volpe Project Implementer Evan Starr Environmental Protection Specialist 617-494-3974 Volpe QA Officer Christopher Zevitas Environmental Engineer 617-494-3611 Laboratory Contact TBD (contracting underway) Analytical Laboratory TBD

Drilling Contact TBD (contracting underway)

Driller TBD

EPA Quality Assurance Officer

Emily Ambeliotis

EPA Project Officer

James Byrne

Volpe Program Manager Michelle Heimgartner

Volpe Quality Assurance Officer

Christopher Zevitas

Volpe Project Implementer

Evan Starr

Laboratory Contractor

TBD

Drilling Contractor

TBD

Brownfields Grantee

NVCOG/CT Land Bank

Grantee Representative

Ricardo Rodriquez

State Regulator

CTDEEP

Site-Specific Quality Assurance Project Plan 3

3.0 Problem Definition & Project Quality Objectives

3.1 Problem Definition

A Phase I ESA (Volpe, 2024a) was completed in April 2023, and updated in December 2024 for property acquisition, by Volpe for the property known as the Kinneytown Dam (Project Site), which is planned for demolition to restore the natural flow of the river. The assessment included a review of historical and environmental records associated with the Project Site and the surrounding area, a Site reconnaissance visit, and interviews with the Project Site manager and local officials. The Phase I assessment identified a recognized environmental condition (REC) in connection with the Project Site based on the potential presence of sediment contamination from suspected historic releases of hazardous materials and/or petroleum products from upstream sources.

Volpe completed a Phase II ESA (Volpe, 2024b) in September 2024 to evaluate the presence or absence of hazardous materials and petroleum products in sediment within the Upper Impoundment and within Coe Pond, and to assess upstream and downstream background conditions. Onsite Phase II ESA activities occurred at the Project Site between May 6 and June 19, 2024. The Phase II ESA included the collection of 64 sediment samples from 30 sediment boring locations within Coe Pond and the Upper Impoundment plus one downstream background sediment boring location and two upstream background sediment boring locations. Phase II activities included sediment sample collection; lithological logging and field screening of sediment borings, including screening with a photoionization detector (PID); and the recording of surface water characteristics. A hazardous building materials inspection survey of buildings and structures was also conducted at the Project Site.

All sediment samples were submitted for laboratory analysis of metals, mercury, herbicides, pesticides, polychlorinated biphenyls (PCBs), volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), extractable total petroleum hydrocarbons (ETPH), and per- and polyfluoroalkyl substances (PFAS). Potential hazardous building materials were inspected, sampled, and analyzed for asbestos-containing materials, lead-based paint, and PCB-containing materials.

Analytical results were compared to Connecticut Department of Energy and Environmental Protection (CTDEEP) Residential Direct Exposure Criteria (DEC) for soil and National Oceanic and Atmospheric Administration (NOAA) Sediment Probable and Threshold Effect Concentration (PEC & TEC) Criteria for Freshwater environments. Additionally, EPA Region 4 Ecological Risk Assessment Supplemental Guidance, Ecological Screening Values (ESVs) and Refinement Screening Values (RSVs) for freshwater sediment were considered. These guidelines are not site-specific clean-up levels.

The primary objective of the 2024 Phase II site activities was to identify the presence or absence of contaminants of concern (CoCs) within Coe Pond and the Upper Impoundment. In order to proceed towards sediment management, the demolition of the dam spillway, and restoration of the Upper Impoundment, additional data is needed to evaluate the identification of CoCs within shallow sediment materials, improve the vertical identification of CoCs within specified locations of the Upper Impoundment, collect additional sediment data for an evaluation of background sediment conditions, and the collection and analysis of elutriate samples for comparison to Connecticut water quality criteria.

Site-Specific Quality Assurance Project Plan 4

3.2 Project Site Description

The Project Site is approximately 171-acres in size and comprises three separate parcels of land between the Town of Seymour and the City of Ansonia in New Haven County, Connecticut:

• 677 South Main Street, Seymour, CT, map-block-lot (MBL): 11-03-35-0, approximately 18 acres

• 769 Derby Avenue, Seymour, CT, MBL: 12-04-34-0, approximately 99 acres

• 0 Hotchkiss Terrace, Ansonia, CT, MBL: 036 0001 0003, approximately 54 acres

New Haven County is situated in southwestern Connecticut. Topography across the Project Site is variable but generally slopes from higher elevations in the north to lower elevations in the south. The Naugatuck River flows north to south and runs from approximately 50 ft. above mean sea level at the Upper Impoundment to approximately 15 ft. above mean sea level south of the Kinneytown Dam spillway. The river flows south from Seymour, CT to Ansonia, CT. A Metro-North commuter rail line runs parallel to the river on the east shore line.

The Project Site generated hydroelectric power from turbines in two powerhouses: the Seymour Unit 1 Powerhouse (Powerhouse 1), adjacent to the Kinneytown Dam spillway; and the Ansonia Unit 2 Powerhouse (Powerhouse 2), located approximately one mile south and adjacent to the Canal Reservoir Dam. The canal and reservoir (known today as Coe Pond) sourced water from the Upper Impoundment for use at Powerhouse 2. The Kinneytown Dam spillway at Unit 1 is located at the following coordinates:

41.368619, -73.085845. The Canal Reservoir Dam structure at Unit 2 is located at: 41.353742, -73.085387 as shown on Figure 3.

The Kinneytown Dam spillway at Unit 1 is 28 feet high and 455 feet wide, with an estimated impoundment area of 72 acres. Located in Seymour, CT, Unit 1 consists of an impoundment, spillway, sluicegate, large filtering grates, fish passage ladder, gatehouse (located on the east bank of the river), buried penstock, floating boat barrier, and Powerhouse 1 which contains a turbine, transformer, and associated equipment. Powerhouse 1 was constructed in the early 1980s and has not produced power since 2020.

The Canal Reservoir Dam at Unit 2 is 30 feet high and 60 feet wide and has an estimated impoundment area of 37 acres. Unit 2 consists of a catwalk, impoundment, spillway, and Powerhouse 2 (sometimes referred to as the “old powerhouse”) which contains a turbine, transformer, and associated equipment.

Powerhouse 2 dates to the 1920s and has not generated power since 2013.

A full Project Site description with detailed information on history, uses, ownership, and features is provided in Phase I – Environmental Site Assessment, Kinneytown Dam, Seymour, Connecticut (Volpe, 2024a). A summary of that description is provided in this section. Please see the Phase I ESA report for additional details, figures, and records. Figures showing the Project Site location, topography of the surrounding area, and the Project Site layout are included as Figures 1, 2, and 3, respectively.

3.2.1 Site History

The original Kinneytown Dam was constructed in 1845 as a diversion dam for a downstream mill and was later converted into a hydroelectric dam (unit 1) with a canal that leads to unit 2 and the Canal Reservoir

Site-Specific Quality Assurance Project Plan 5

Dam downstream. Floods have twice destroyed the Kinneytown Dam, once in 1910 and again in 1955, and it was rebuilt each time. It is currently in need of repair according to a Federal Energy Regulatory Commission (FERC) communication from 2022 and has been rated as a significant hazard by CTDEEP since 2016 and the fish ladder is no longer operable.

In 2023 and 2024, inspection surveys were performed of the Canal Reservoir Dam at Coe Pond and several structural deficiencies with the potential for risk to public safety and the environment were identified. In response to the inspection survey findings, corrective actions were undertaken from September to October 2024 to lower the water level at the Canal Reservoir Dam to reduce pressure on the dam and lower the risk of potential failure.

3.2.2 Current Ownership and Use

The Project Site is currently owned by Trimaran Energy, LLC and is not in use. All structures listed above are either abandoned or otherwise not in use.

Metro-North Commuter Railroad Company, a subsidiary of the Metropolitan Transportation Authority (MTA), holds a leasing agreement from 1984 with Arco Metals Company for wire, pipe, and cable crossings associated with the rail line adjacent to the Dam property.

3.2.3 Proposed Development

All structures associated with Unit 1 and Unit 2, including the Kinneytown Dam spillway and Canal Reservoir Dam are slated to be removed and the surrounding river restored.

3.3 Contaminants of Concern

Multiple contaminants have been observed in sediment in Coe Pond and the Upper Impoundment that exceed NOAA PEC/TECs and EPA ESV/RSVs. NOAA TEC and EPA ESV screening levels are based on chemical concentrations below which adverse effects are not expected to occur. Exceedances of TEC and ESV are common and widespread across the northeastern US and could be typical of background or ambient concentrations. As such, PEC/RSVs are often used to identify CoCs in sediment.

Based on the results of the 2024 Phase II at the Project Site, the following contaminants of concern were identified exceeding NOAA PEC and EPA RSVs:

Table 2: Contaminants of Concern Contaminant Media Location Identified

Metals Coe Pond Upper Impoundment

Arsenic Sediment X Barium Sediment X X Cadmium Sediment X X Total Chromium Sediment X X Copper Sediment X X Lead Sediment X X Mercury Sediment X X

Site-Specific Quality Assurance Project Plan 6

Contaminant Media Location Identified Metals Coe Pond Upper

Impoundment Silver Sediment X X Zinc Sediment X X Tetrachloroethylene (PCE) Sediment X Toluene Sediment X X Ethylbenzene Sediment X Total xylenes Sediment X Styrene Sediment X Carbon disulfide Sediment X Isopropylbenzene (cumene) Sediment X X p-isopropyltoluene Sediment X X Naphthalene Sediment X X 1,2,4-trichlorobenzene Sediment X 1,3,5-trimethylbenzene Sediment X X 1,2,4-trimethylbenzene Sediment X X

SVOCs Sediment Fluoranthene Sediment X X bis (2-ethylhexyl) phthalate Sediment X X Benzo(a)pyrene Sediment X X Chrysene Sediment X X Anthracene Sediment X X Fluorene Sediment X X Phenanthrene Sediment X X Pyrene Sediment X X Aniline Sediment X X 4-chloroaniline Sediment X Dibenzofuran Sediment X 3-methylphenol/ 4-methylphenol

Sediment X X

NDPA/DPA Sediment X X

ETPH

ETPH Sediment X X PCBs

Aroclor 1242 Sediment X Aroclor 1254 Sediment X X Aroclor 1260 Sediment X Aroclor 1268 Sediment X Total PCBs Sediment X X

Pesticides Dieldrin Sediment X 4,4’-DDE Sediment X X 4,4’-DDD Sediment X X 4,4’-DDT Sediment X X Chlordane Sediment X X

The primary focus of supplemental Phase II activities will be on Upper Impoundment sediment and sediment downstream and upstream of the Project Site. Contaminants of concern for further investigation are listed in Table 6.

Site-Specific Quality Assurance Project Plan 7

3.4 Tasks to be Performed

The supplemental Phase II ESA investigation will include the following tasks, which will be conducted in accordance with the Volpe Brownfields Generic QAPP (Volpe, 2023a) and applicable Volpe Standard Operating Procedures (SOPs). A schedule for these tasks is provided in Section 4.0.

• Field Documentation – Field data will be recorded, including a list of each sample ID; date, time, and depth of collection; weather conditions; any evidence of odors, sheens, or soil staining; and general physical characteristics. Sediment sample locations and elevation will be recorded and located with a hand-held GPS. Additionally, photographs will be taken to document each sediment core interval and sample location.

• Equipment Mobilization – Sediment sampling will begin downstream and move upstream (northward). A telehandler forklift or excavator will be utilized to lift and place a drilling platform with drilling equipment into the Housatonic River at O’Sullivan’s Island Recreation Park and Derby Greenway in Derby, CT. The equipment will be moved east and then north towards the southern outlet of the Naugatuck River for downstream background sampling. Upon completion, the equipment will be remobilized to the Derby Avenue Pump Station for Upper Impoundment sampling. Following Upper Impoundment sampling, equipment will be remobilized north to the Naugatuck River Greenway Trail, just north of the Tingue Dam in Seymour, CT to facilitate the collection of upstream background samples. Please see Section 3.6 for additional details.

• Sediment Boring Advancement – A minimum of 28 sediment borings will be advanced in accordance with EPA Methods for Collection, Storage and Manipulation of Sediments for Chemical and Toxicological Analyses: Technical Manual (2001). Borings will be advanced to bedrock or refusal. Surface water is anticipated to be less than 5 ft. deep within the Upper Impoundment and 5-10 ft. deep at the background sample locations. Borings will be located as described in Section

3.5 and in Figures 4 – 6, and advanced at four downstream locations south of the Upper Impoundment, 20 locations in the Upper Impoundment, and four upstream locations north of the Upper Impoundment. The 20 Upper Impoundment borings will be distributed along three cross-sectional segments of five borings each with five additional boring locations distributed along the Naugatuck River that will be advanced at the midpoint of the river.

o A hybrid drilling approach will be used for collecting samples that will utilize vibracore and ponar samplers for shallow sediment/near surface soft materials to improve sample recoveries, and a split-spoon sampler and mechanical drill for deeper and more dense sandy silt/silty clay material layers. Section 3.5 provides additional details on the drilling approach.

• Sediment Sample Collection – Samples will be collected during Supplemental Phase II activities for laboratory physical characterization (total organic carbon, total solids, and grain size analysis), chemical analyses, and elutriate analyses. Sediment samples will be collected from each of the completed sediment borings. All sediment cores will undergo field characterization and will be screened by strata type and by visual/olfactory observations. Additionally, sediment will be screened in the field with a calibrated photoionization detector (PID) for the presence of volatiles.

Site-Specific Quality Assurance Project Plan 8

Material for sediment chemistry analyses will be collected from all standalone boring locations and from two of the locations within each Upper Impoundment cross-sectional segment. As detailed in the following bullet, a total of six elutriate samples will also be collected. A table summarizing proposed sediment samples is included in Section 5.1. Figures 4, 5, and 6 identify Upper Impoundment, downstream background, and upstream background locations, respectively. Samples will be screened and collected in accordance with EPA Methods for Collection, Storage and Manipulation of Sediments for Chemical and Toxicological Analyses:

Technical Manual (2001) and CTDEEP Guidance for Collecting and Preserving Soil and Sediment Samples for Laboratory Determination of Volatile Organic Compounds and relevant Volpe SOPs, including SOP-003 Description and Identification of Soils, SOP-004 Soil Headspace Screening, SOP- 005 Surficial Soil Sediment and Sludge Sampling, SOP-008 Split-Spoon/Spilt-Barrel Sampling, and SOP-018 Field Sampling Equipment Decontamination.

• Elutriate Sample Collection – Elutriate samples will be collected in accordance with EPA/USACE guidance (Evaluation of Dredged Material Proposed for Discharge in Waters of the U.S. - Inland Testing Manual (USEPA/USACE 1998)) and Volpe SOP-026 Sediment Sample Collection for Elutriate Analysis. Elutriate chemistry analysis will be performed from two of the cross-sectional sampling segments to evaluate compliance with CT Water Quality Standards (Regs. Conn. State Agencies § 22a-422) (CTDEEP, 2015). As shown in Figure 4, elutriate samples will be collected from the center sample locations in Segments 1 and 2. At each of these sample locations, materials will be collected from one location and composited together to collect sufficient water column and sediment volume. Each sample interval will be composited from homogenous layers representing the full vertical column of sediment. If sufficient volume is not obtainable from one drilling location, an additional location will be advanced 5-10 ft. away and repeated until sufficient volume is recovered for sample collection, following horizontal/vertical homogeneity. Three samples will be collected from different sediment depths, from Segment 1, and three samples from Segment 2 for six total samples. Each sample set includes composited materials collected from the sub-surface sediments and water collected from the water column at each boring location.

• Physical Characterization of Sediment – Laboratory physical characterization of sediment will be performed in all sediment samples collected and analyzed for total organic carbon, total solids, and grain size analysis. Additionally, three cross-sectional segments within the Upper Impoundment include cross-sectional coring to facilitate evaluation and definition of the pre-dam channel location. Proposed cross-sectional segments are shown in Figure 4. Standard Penetration Testing (SPT) blow counts will be recorded at all coring locations for sediment management evaluations.

• Surface Water Screening – Surface water will be field-measured for physical and chemical characteristics including depth to sediment, turbidity, dissolved oxygen, specific conductance, temperature, pH, and oxidation/reduction potential. Surface water will be collected from the surface of each drilling location and screened in accordance with Volpe SOP-016 Surface Water Sampling.

Site-Specific Quality Assurance Project Plan 9

• Sediment and Elutriate Sample Analysis – Sediment and elutriate samples will be handled in accordance with Volpe SOP-019 Sample Labeling, Packaging, and Shipping and Volpe SOP-026 Sediment Sample Collection for Elutriate Analysis. Samples will be sent to an approved laboratory for laboratory analysis.

• Equipment Demobilization – Following sample collection, equipment will be appropriately removed from the Project Site. Waste will be handled in accordance with Volpe SOP-020 Management of Investigation Derived Waste. IDW was not generated during initial Phase II activities, however, if necessary, waste will be containerized in buckets on the drilling platform and transferred to 55-gallon drums when returned to boat launch location.

• Data QA and Analysis – Volpe will request a Level II data package for all sample data. Data received from the laboratory will be reviewed for quality as described in the Volpe Brownfields Generic QAPP. Laboratory analytical results shall be compared to the regulatory standards and guidance values discussed in Section 3.8 and used to inform the decision statement provided in Section 3.9.

Additionally, sediment data with low percent solids will be qualified as detailed in Section 5.2.

• Reporting – The sampling investigation activities, findings, and recommendations will be summarized in a Supplemental Phase II ESA Report, which will include data tables documenting sample locations, sediment and water depths, lithology findings and analytical results, site figures, and laboratory analytical reports. The report will be submitted to the EPA Project Officer and shared with the grantee to inform decision making and identify appropriate next steps. Data reporting is further discussed in Section 11.0.

3.5 Sampling Locations and Rationale

Sediment sampling will be collected from a minimum of twenty (20) sample locations from within the Upper Impoundment, with four (4) additional sample locations upstream (north) of the impoundment area and four (4) sample locations downstream (south) of the Kinneytown Dam, near the southern extent of the Naugatuck River. Sample locations are shown in Figures 4, 5, and 6 but are subject to change, with the approval of the Volpe Project Implementer, based on site conditions, such as shallow surface water preventing access for the drilling platform. A table of proposed sediment samples is included in Section

5.1. Proposed sample locations and segments were developed based on Phase II digital boring log findings, laboratory physical characterization (grain size) data, and previously accessible sediment sample locations, related to surface water depths.

Initial Phase II sediment recovery rates varied throughout the project area due to the presence of soft sandy materials. Throughout the Upper Impoundment, poor recovery was observed from upper sediment materials (0 – 5 ft. below sediment surface). Large volumes of material were required for the broad suite of laboratory analyses and low recovery rates made collection of sufficient volumes of materials difficult, resulting in the need to composite samples over multiple intervals. To address these data gaps, a hybrid drilling approach will be utilized to improve sediment recovery rates as discussed below.

At each sample location, the drilling operator will first deploy a vibracore sampler to collect surficial sediment materials (0-6 ft. bss). If vibracore samplers do not return sufficient sediment volume for

Site-Specific Quality Assurance Project Plan 10 characterization and sample collection, a ponar sampler will be advanced to collect near-surficial sediment. Following the collection of surficial sediment samples, a split-spoon sediment core sampler will be advanced from 6 ft. bss down to bedrock and/or refusal. Anticipated depths of sediment cores will vary across the impoundment areas due to changes in river topography and sediment build-up. During initial Phase II activities, sediment thickness ranged from approximately 10-20 ft. bss along the southern extent of the Upper Impoundment, increasing to 10-35 ft. bss in the central parts of the Impoundment, and decreasing to 5-15 ft. bss along the northern extent of the Upper Impoundment. If shallow refusal is encountered above bedrock due to the presence of debris or other materials, a new sampling location and sampling core shall be established in the near vicinity and confirmed by on-site personnel, within a 10-ft. radius of the original location.

At each sample location, cores will be deployed and collected so that each sampled interval is representative of various depths of the sediment column. For example, two to three sample intervals are anticipated at each sample location, depending on total depth: one surficial sediment interval and one to two sample intervals, each 2-4 ft. thick, from sandy silt/silty clay layers (depths are expected to vary within the Upper Impoundment). Proposed elutriate sediment samples will be collected from composited homogenous layers representing the full vertical column of sediment.

Due to the volume of material required for proposed sampling methods and limited volume collected from prior sediment cores, multiple borings in the vicinity of each sample location may be required to obtain the desired quantity of material from a given depth. Large-diameter cores (3-in. diameter) will be used for sample collection to minimize the amount of cores needed. Where multiple borings are required, samples will be collected from similar stratigraphy and depth to obtain homogenous composite samples.

Investigation derived waste (IDW) will be field screened during sampling operations. If visual or olfactory observations indicate potential contaminated material and/or field screening identifies PID concentrations equal to or greater than 50 ppm, sample cuttings will be containerized in buckets on the drilling platform and transferred to 55-gallon drums upon return to the boat launch area, for waste characterization analysis. If field screening does not indicate impacted materials, sample cuttings can be returned to the river/pond/impoundment from which they were collected.

3.6 Sampling Media and Parameters

Samples will be prepared for laboratory analysis by compositing material from within each sediment core interval, with the exception of volatiles which will be collected directly from the core immediately following sample retrieval. Sample cores will be field screened for VOCs by a photoionization detector (PID) and cores with the highest-detected readings within each sample interval will be targeted for VOC sample collection. To the extent practical, composite samples will be prepared from cores collected from the same layer within each sample interval. VOC samples will be collected in accordance with CTDEEP Guidance for Collecting and Preserving Soil and Sediment Samples for Laboratory Determination of Volatile Organic Compounds.

Elutriate analysis will be performed in accordance with New England District Regional Implementation Manual (USEPA/USACE, 2004) and Evaluation of Dredged Material in Waters of the U.S. ‐ Testing Manual, Site-Specific Quality Assurance Project Plan 11

EPA‐823‐B‐98-004 (USEPA/USACE, 1998). The laboratory will prepare samples based on a 4 part water to 1 part sediment ratio. Each sample will be mixed for 30 minutes in a non‐contaminating vessel and then allowed to settle for 60 minutes. The resulting supernatant will be siphoned from the container and centrifuged to remove suspended particulate material. Chemical analysis for each parameter must be carried out in triplicate, for the elutriate solution, the blank preparation water, and the assay dilution water.

Sediment samples will be analyzed for the following parameters:

• Sediment description/classification and physical characteristics including total organic carbon, grain size distribution analysis, organic content, moisture content, percent solids, and pH

• Field screened for VOCs by photoionization detector (PID)

• Laboratory analysis of metals, VOCs, SVOCs, PCBs, and pesticide concentrations

Elutriate samples will be analyzed for the following parameters:

• Laboratory analysis of metals, SVOCs, PCBs, and pesticide concentrations (VOCs are not included in elutriate analysis)

Surface water samples will be field measured for the following parameters:

• Depth

• Turbidity, dissolved oxygen, specific conductance, temperature, pH, and oxidation/reduction potential

3.7 Regulatory Standards and Guidance Values

Analytical results shall be compared to the NOAA Sediment Threshold Effect Concentrations (TEC) and Probable Effect Concentration (PEC) Criteria for Freshwater Environments (MacDonald et al., 2000).

Additionally, EPA Region 4 Ecological Risk Assessment Supplemental Guidance, Ecological Screening Values (ESVs) and Refinement Screening Values (RSVs) for freshwater sediment (USEPA, 2018) will be utilized for analytes without NOAA TEC/PECs. The NOAA PEC and EPA RSV screening levels will be prioritized as they are a better indicator of the potential ecological impact of Project Site sediments. These guidelines are not intended to serve as site-specific clean-up levels but will be used in the decision-making process regarding future plans.

The applicable CT Water Quality Standards, 22a-426-1 et seq., (CTDEEP, 2015) will be used to evaluate the elutriate chemistry and surface water characterization. As cited in Sec. 22a-426-4(a)(5): “surface waters and sediments shall be free from chemical constituents in concentrations or combinations which will or can reasonably be expected to result in acute or chronic toxicity to aquatic organisms or otherwise impair the biological integrity of aquatic or marine ecosystems outside of any dredged material disposal area…In determining consistency with this Standard, the Commissioner shall at a minimum consider the numeric criteria listed in Table 3 of section 22a-426-9 of the Regulations of Connecticut State Agencies.”

Sediment and Water Quality Standards

The NOAA SQG guidelines (MacDonald, 2000) present screening concentrations for inorganic and organic

Site-Specific Quality Assurance Project Plan 12 contaminants in various environmental media. To screen for substances which may threaten natural resources of concern to NOAA, laboratory analytical concentrations can be compared to these screening levels. Freshwater PEC values will be included for comparison. The RSVs provided by EPA Region 4 guidance represent a preliminary screening of site chemical concentrations to assist in evaluating the need to conduct further investigations at the site.

In accordance with CT Sec. 22a-426-4(h), surface water within the Project Site is classified as Class B waters. Field-measured surface water characterization will be compared to Sec. 22a-426-9(a)(1) Table 1 Surface Water Criteria. Elutriate analytical results will be compared to acute and chronic Aquatic Life Criteria: Freshwater Class AA, A, and B under Sec. 22a-426-9(a)(5) Table 3 Numerical Water Quality Criteria for Chemical Constituents.

Table 3 below summarizes these categories.

Table 3: Categories of Screening Values Criteria Definition Applicability to the Project Site

NOAA PEC PECs are used to identify sediments that are likely toxic to sediment-dwelling organisms.

Exceedance of PECs may indicate the need for further site assessment and/or risk characterization.

EPA Region 4 RSVs

The RSVs represent a preliminary screening of site chemical concentrations to assist in evaluating the need to conduct further investigations at the site.

Exceedance of the RSVs may indicate the need for further site assessment and/or risk characterization.

CT-WQS Surface Water Criteria: Class B Surface water at each sample location will be field-measured and screened for DO, turbidity, pH, and temperature.

CT-WQS Aquatic Life Criteria: Freshwater Class AA, A, and B Acute and Chronic toxicity

Dissolved contaminants will be compared to WQS. Potential released or dredged material must meet applicable WQS for all CoCs.

3.8 Decision Statement

Future plans for the Project Site include demolition of dam structures and sediment management, which may include passive release downstream, dredging for off-site disposal, or dredging for downstream in-situ capping. As stated above, a primary goal of this Supplemental Phase II investigation is to evaluate sediment contaminant concentrations to inform the development of future sediment management strategies. Specific findings from this investigation will be evaluated as follows:

• Data will be evaluated to determine/identify:

o Nature and extent of contamination.

o Contaminants exceeding screening thresholds and the magnitude of exceedances.

o Data quality and usability.

• NOAA freshwater PECs and EPA RSVs will be used as benchmark screening thresholds. Exceedance of these values may indicate the need for further site assessment and/or risk characterization.

Site-Specific Quality Assurance Project Plan 13

• Compare measured contaminant concentrations to determine if they are consistent with measured concentrations found in upstream and downstream background sample locations.

Compare elutriate chemistry data to CT WQS Aquatic Life Criteria Class B waters for CoCs. Discharges to surface waters shall meet the criteria listed to ensure that such discharges do not cause acute or chronic toxicity to freshwater and marine aquatic life or impair the biological integrity of freshwater and marine ecosystems (CTDEEP, 2015).

4.0 Project Timeline

Volpe will complete the Supplemental Phase II ESA based on the schedule provided in Table 4 below.

The schedule is subject to change.

Table 4: Project Timeline

Activity Duration (business days)

Volpe preparation of SSQAPP 30 EPA review of SSQAPP 30 Volpe prepares SOW for laboratory and drilling contract support 5 Volpe contracts laboratory and drilling support 40 Drilling contractor prepares work plan and health and safety plan 15 Volpe and EPA schedule field work 10 Conduct field work (mobilization, drilling, sample collection) 20 Laboratory analysis 15 Data QA review and report preparation 40

5.0 Sampling and Analytical Requirements

5.1 Sample Summary

A summary of all samples to be collected and analyzed during the Supplemental Phase II ESA is provided in Table 5 below. Sample locations and depths are subject to change based on site conditions.

Table 5: Sample Summary Location Easting Northing Sample ID Sample Depth -

Below Sediment Surface (bss) Laboratory Analysis

Upper Impoundment Sediment SED-201 907849.9 695601.4 SED-201A 0-4 ft. bss Physical Charact.

SED-201B 4 ft. to refusal. bss Physical Charact.

SED-202 907943.4 695577.1 SED-202A 0-4 ft. bss Full list in Table 7

SED-202B Approx. 7-10 ft. bss Full list in Table 7 SED-203C Approx. 12-15 ft. bss Full list in Table 7

SED-203 908044.7 695555.8 SED-203A 0-4 ft. bss Physical Charact.

SED-E1A* 0-6 ft. bss Elutriate Analysis SED-E1B* Approx. 6-10 ft. bss Elutriate Analysis SED-203B Bottom of casing Physical Charact.

SED-E1C* Bottom, approx. 10-14 ft. bss Elutriate Analysis

Site-Specific Quality Assurance Project Plan 14

Location Easting Northing Sample ID Sample Depth - Below Sediment Surface (bss)

Laboratory Analysis

SED-204 908159.0 695526.5 SED-204A 0-4 ft. bss Full list in Table 7 SED-204B Approx. 6-9 ft. bss Full list in Table 7 SED-204C Approx. 10-13 ft. bss Full list in Table 7

SED-205 908268.8 695494.1 SED-205A 0-4 ft. bss Physical Charact.

SED-205B 4 ft. to refusal. bss Physical Charact.

SED-206 908629.4

697065.1 SED-206A 0-4 ft. bss Full list in Table 7

SED-206B Approx. 6-9 ft. bss Full list in Table 7 SED-206C Approx. 9-12 ft. bss Full list in Table 7

SED-207

908767.7 697578.3 SED-207A 0-4 ft. bss Full list in Table 7 SED-207B Approx. 4-7 ft. bss Full list in Table 7 SED-207C Aprrox. 7-10 ft. bss Full list in Table 7

SED-208 908821.6 698138.1 SED-208A 0-4 ft. bss Physical Charact.

SED-208B 4 ft. to refusal. bss Physical Charact.

SED-209 908935.3 698128.6 SED-209A 0-4 ft. bss Full list in Table 7 SED-209B Approx 4-7ft. bss Full list in Table 7 SED-209C Approx. 7-10 ft. bss Full list in Table 7

SED-210 909066.4 698116.4 SED-210A 0-4 ft. bss Physical Charact.

SED-E2A* 0-8 ft. bss Elutriate Analysis SED-210B 4 ft. to refusal. bss Physical Charact.

SED-E2B* Approx. 8-14 ft. Elutriate Analysis SED-E2C* Approx. 14 ft. to bottom Elutriate Analysis

SED-211 909185.5 698104.5 SED-211A 0-4 ft. bss Full list in Table 7 SED-211B Approx. 8-11 ft. bss Full list in Table 7 SED-211C Approx. 12-15 ft. bss Full list in Table 7

SED-212 909294.8 698098.4

SED-212A 0-4 ft. bss Physical Charact.

SED-212B 4 ft. to refusal. bss Physical Charact.

SED-213 909174.6 698402.7 SED-213A 0-3 ft. bss Full list in Table 7 SED-213B Approx. 8-11 ft. bss Full list in Table 7 SED-123C Approx. 12-15 ft. bss Full list in Table 7

SED-214 909424.7 698956.1 SED-214A 0-4 ft. bss Full list in Table 7 SED-214B Approx. 7-10 ft. bss Full list in Table 7 SED-214C Approx. 10-13 ft. bss Full list in Table 7

SED-215 909593.0 699240.9 SED-215A 0-4 ft. bss Full list in Table 7 SED-215B Approx. 6-9 ft. Full list in Table 7 SED-215C Approx. 9-12 ft. Full list in Table 7

SED-216 909519.0 699558.1 SED-216A 0-4 ft. bss Physical Charact.

SED-216B 4 ft. to refusal. bss Physical Charact.

SED-217 909614.8 699535.9 SED-217A 0-4 ft. bss Full list in Table 7 SED-217B Approx. 7-10 ft. bss Full list in Table 7 SED-217C Approx. 10-13 ft. bss Full list in Table 7

SED-218 909706.2 699512.7 SED-218A 0-4 ft. bss Physical Charact.

SED-218B 4 ft. to refusal. bss Physical Charact.

SED-219 909800.8 699487.2 SED-219A 0-4 ft. bss Full list in Table 7 SED-219B Approx. 7-10 ft. bss Full list in Table 7 SED-219C Approx. 10-13 ft. bss Full list in Table 7

SED-220 909892.1 699458.6 SED-220A 0-4 ft. bss Physical Charact.

SED-220B 4 ft. to refusal. bss Physical Charact.

Site-Specific Quality Assurance Project Plan 15

Location Easting Northing Sample ID Sample Depth - Below Sediment Surface (bss)

Laboratory Analysis

Downstream Background Sediment

DWN-

BKGD-01

908877.4 677421.3 DWN-BKGD-01A 0-4 ft. bss Full list in Table 7 DWN-BKGD-01B 4 ft. to refusal. bss Full list in Table 7

DWN-

BKGD-02

908680.6 676947.7 DWN-BKGD-02A 0-4 ft. bss Full list in Table 7 DWN-BKGD-02B 4 ft. to refusal. bss Full list in Table 7

DWN-

BKGD-03

908974.4 676522.9 DWN-BKGD-03A 0-4 ft. bss Full list in Table 7 DWN-BKGD-03B 4 ft. to refusal. bss Full list in Table 7

DWN-

BKGD-04

908889.3 676025.1 DWN-BKGD-04A 0-4 ft. bss Full list in Table 7 DWN-BKGD-04B 4 ft. to refusal. bss Full list in Table 7

Upstream Background Sediment

UP-BKGD-

910413.0 704734.6 UP-BKGD-01A 0-4 ft. bss Full list in Table 7 UP-BKGD-01B 4 ft. to refusal. bss Full list in Table 7

UP-BKGD-

910379.8 705206.2 UP-BKGD-02A 0-4 ft. bss Full list in Table 7 UP-BKGD-02B 4 ft. to refusal. bss Full list in Table 7

UP-BKGD-

911367.8 705562.8 UP-BKGD-03A 0-4 ft. bss Full list in Table 7 UP-BKGD-03B 4 ft. to refusal. bss Full list in Table 7

UP-BKGD-

912115.7 706249.4 UP-BKGD-04A 0-4 ft. bss Full list in Table 7 UP-BKGD-04B 4 ft. to refusal. bss Full list in Table 7

1. Location easting and northing are based on the North American Datum 1983 State Plane Connecticut FIPS 2001 (US Feet) Projected Coordinate System.

2. The number of interval samples per location may change depending on variable field conditions (depth of sediment within different areas of impoundment).

3. Quality control samples will be collected in addition to the samples listed in this table and are listed in Table 9.

5.2 Field Measurements

Measurements to be collected in the field include:

• SPT blow counts at each drilling location.

• Sediment descriptions and classifications which will be recorded in the field notebook to document sediment characteristics.

• PID readings which will be used on individual sediment samples and the sediment cores to screen for volatiles, visual, and/or olfactory signs of contamination in the material. Readings will be recorded in the Volpe Boring and Well Construction Log.

• Surface water quality measurements including turbidity, dissolved oxygen, specific conductance, temperature, and pH.

• Total depth of sediment.

• GPS sample locations and elevations.

5.3 Sample Analysis

Sediment samples will be analyzed for the parameters listed below in Table 6. Quality control (QC) samples are not included in this table (please see Table 9). The laboratory SOPs for each analysis are listed in Table 7. Copies of the laboratory SOPs are provided in the Volpe Brownfields Generic QAPP.

A complete list of analytes to be included for each parameter is provided in Appendix A. The list includes the laboratory reporting limits as well as the regulatory standards for each analyte as described in Section

Site-Specific Quality Assurance Project Plan 16

3.7 of this SSQAPP. For analytes whose listed laboratory reportable detection limit (RDL) is greater than the strictest applicable regulatory standard, Volpe will coordinate with the lab to determine if lower RDLs are achievable. If they are not, a “J”-qualified estimated concentration that is less than the RDL but greater than the analyte’s method detection limit will be evaluated. If reliable chemical concentrations still cannot be achieved, then the need for resampling will be discussed on a case-by-case basis with the EPA Program Officer.

In accordance with EPA Region 1 Memorandum on Qualifying Soil/Sediment Data with low Percent Solids (EPA 1990), sediment data will be accepted when the percent solids are greater than 30%. A “J”-qualified result will be added when positive results include percent solids 10% or greater and less than or equal to 30%. All positive results are to be rejected when percent solids are less than 10%. All non-detected results are to be rejected when percent solids are less than or equal to 30%.

Table 6: Laboratory Analytical Summary

Parameter # of Samples*

Analysis Method Container Preservative Holding Time

Sediment

CT15 Metals 49 EPA 6010D

1 Plastic container or 1 x 4 oz. glass jar

Cool to 4˚C 180 days

Mercury 49 EPA 7471B 1 Plastic container or 1 x 4 oz. glass jar

Cool to 4˚C 28 days

RCP VOCs low-level

49 EPA 8260 3 x 40 mL glass Teflon lined vials; 1 x 2oz. jar for percent moisture

1 vial with 5 mL methanol;

2 vials with 5 mL water or sodium bisulfate solution, cool to 4˚C

14 days

RCP SVOCs 49 EPA 8270 1 x 8 oz. amber glass jar

Cool to 4˚C 14 days

PCBs 49 EPA 8082

1 x 8 oz. amber glass jar

Cool to 4˚C 365 days extract, 40 days analyze

Pesticides 49 EPA 8081B 1 x 8 oz. amber glass jar

Cool to 4˚C 14 days

Elutriate

Metals 6 EPA 1632/6020B/7474A

1** Polyethylene or glass container with Teflon-lined lid.

Cool to 4˚C

14 days

PCBs 6 EPA 8270D

SVOCs 6 EPA 8270D

Pesticides 6 EPA 8081B Physical Characterization

Total Solids 70 EPA 2540 1 x 2 oz. Plastic Container

Cool to 4˚C - Total Organic Carbon

70 EPA 9060A

1 x 8 oz. Plastic Container Grain Size

Analysis

70 ASTM D6913/D7928

Site-Specific Quality Assurance Project Plan 17

Parameter # of Samples*

Analysis Method Container Preservative Holding Time

* Total number of samples should not exceed. Actual number of interval samples per location may change depending on variable field conditions (depth of sediment within different areas of impoundment).

**Total number of containers per parameter will be directed by laboratory.

Field-measurements for surface water include turbidity, dissolved oxygen, specific conductance, temperature, and pH.

Table 7: Alpha Analytical Laboratory SOP References

Lab

SOP

Title Reference Method

Version, Date

32639 Volatile Organic Compounds by GC/MS EPA 8260D 8, 11/08/2022 31162 Semivolatile Organic Compounds by GC/MS EPA 8270E 2, 04/29/2021 2116 Organochlorine Pesticides by Capillary Column GC EPA 8081B 10, 11/08/2022 2129 PCBs by Capillary Column GC EPA 8082A 12, 11/08/2022 26796 Inductively Coupled Plasma - Atomic Emission Spectrometry (metals) EPA 6010D 3, 07/08/2022 25924 Mercury in Solid or Semisolid Waste (Manual Cold-Vapor Technique) EPA 7471B 4, 07/07/2022 2204 Chromium, Hexavalent EPA 7194A 10, 01/06/2022

6.0 Project Specific SOP References

Volpe SOPs that are to be utilized in the field during the Supplemental Phase II ESA are listed in Table 8 below. Copies of these SOPs are attached to the Volpe Brownfields Generic QAPP. SOP-026 is currently pending review to be added to the Generic QAPP but will be included in the SOPs appendix.

Table 8: Project Specific SOP References Volpe SOP Title Version, Date SOP-001 Field Notebook Use 1.0, 01/09/23 SOP-002 Site Access and Utility Clearance 1.0, 01/09/23 SOP-003 Description and Identification of Soils 1.0, 01/09/23 SOP-004 Soil Headspace Screening 1.0, 01/09/23 SOP-005 Surficial Soil Sediment and Sludge Sampling 1.0, 01/09/23 SOP-008 Split-Spoon/Split-Barrel Sampling 1.0, 01/09/23 SOP-009 Field Preservation of VOA Soil and Sediment Samples 1.0, 01/09/23 SOP-010 Direct Push Technique Drilling 1.0, 01/09/23 SOP-011 Hallow Stem Auger Drilling 1.0, 01/09/23 SOP-013 Monitoring Well and Piezometer Installation 1.0, 01/09/23 SOP-015 Low-Flow Groundwater Sampling and Groundwater Level Measuring 1.0, 01/09/23 SOP-016 Surface Water Sampling. 1.0, 01/09/23 SOP-018 Field Sampling Equipment Decontamination 1.0, 01/09/23 SOP-019 Sample Labeling, Packaging, and Shipping 1.0, 01/09/23 SOP-020 Management of Investigation Derived Waste 1.0, 01/09/23 SOP-026 Sediment Sample Collection for Elutriate Analysis 1.0, 06/03/25

7.0 Field Equipment Calibration & Corrective Action

The PID, water quality meter, and turbidity meter will be calibrated in the field according to the manufacturer specifications. Frequency and procedures for field calibration of these instruments are provided in Volpe SOP-004 Soil Headspace Screening and SOP-016 Surface Water Sampling. Field equipment calibration and corrective action is further discussed in the Volpe Generic Brownfields QAPP.

Site-Specific Quality Assurance Project Plan 18

8.0 Laboratory Equipment Calibration & Corrective Action

The laboratory equipment calibration procedures will be performed by the individual laboratories.

Method-specific calibration and corrective action…