Lower_Assunpink_Final_RIR-RAR_-_Watermark_Env._(11.04.16).pdf

AMENDMENT OF SOLICITATION/MODIFICATION OF CONTRACT

Except as provided herein, all terms and conditions of the document referenced in Item 9A or 10A, as heretofore changed, remains unchanged and in full force and effect.

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FAR (48 CFR) 53.243

This amendment releases the follow ing report: "Remedial Investigation Report / Remedial Action Report"

1. CONTRACT ID CODE PAGE OF PAGES

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X 9B. DATED (SEE ITEM 11)

16-May-2017

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9A. AMENDMENT OF SOLICITATION NO.

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CODE

CONTR DIV-CONTRACTS BR

USACE, PHILA DISTRICT

WANAMAKER BUILDING

100 PENN SQUARE EAST

PHILADELPHIA PA 19107-3390

W912BU 7. ADMINISTERED BY (If other than item 6)

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See Item 6

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Final

Remedial Investigation Report / Remedial Action Report

November 2016

Lower Assunpink Creek Restoration Project 25 E. Lafayette Street & 310 S. Warren Street Trenton, Mercer County, New Jersey 08608

PI # 615053

Case # 10-12-08-0959-48

Trenton, New Jersey

Prepared for:

City of Trenton 319 East State Street Trenton, NJ 08608

Prepared by:

Watermark Environmental, Inc.

175 Cabot Street

Lowell, Massachusetts 01854

Remedial Investigation Report / Remedial Action Report

Lower Assunpink Creek Restoration Project

25 E. Lafayette Street & 310 S. Warren Street Trenton, Mercer County, New Jersey 08608

PI # 615053

Case # 10-12-08-0959-48

Prepared for:

City of Trenton, New Jersey Department of Housing and Economic Development

319 East State Street

Prepared by:

Watermark Environmental 175 Cabot Street

Lowell, MA 01854

And

Arecon Ltd.

90 US Highway 130

Bordentown, NJ 08505

November 4, 2016

Patrick G. Nocera, LSRP

LSRP ID No. 585046

Watermark

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TABLE OF CONTENTS

SECTION PAGE

1.0 INTRODUCTION AND BACKGROUND ................................................................................. 1-1

1.1 Project Location and Setting ..................................................................................................... 1-1

1.2 Prior Environmental Investigations .......................................................................................... 1-2

2.0 PHYSICAL SETTING AND GENERAL SITE DESCRIPTION ............................................. 2-1

2.1 Soils, Geology, and Hydrogeology ........................................................................................... 2-1

2.2 Surface Water ............................................................................................................................ 2-1

3.0 CURRENT AND HISTORICAL USE INFORMATION .......................................................... 3-1

3.1 Target Site ................................................................................................................................. 3-1

3.2 Surrounding Properties ............................................................................................................. 3-1

4.0 JANUARY 2013 GROUNDWATER MONITORING ............................................................... 4-1

5.0 JUNE 2014 REMEDIAL INVESTIGATION ............................................................................. 5-1

5.1 Monitoring Well Decommissioning .......................................................................................... 5-1

5.2 AOC-1 – Benzene Impact to Ground Water Pathway, AC-03 ................................................. 5-1

5.3 AOC-2 – Elevated PCB Concentrations in Soil at SB-02 and SB-04 ....................................... 5-1

6.0 RECEPTOR EVALUATION AND ECOLOGICAL EVALUATION ..................................... 6-1

7.0 INTERIM REMEDIAL MEASURES ......................................................................................... 7-1

7.1 Soil Reuse Sampling ................................................................................................................. 7-1

7.2 Waste Characterization Sampling and Soil Disposal ................................................................ 7-2

8.0 TECHNICAL OVERVIEW ......................................................................................................... 8-1

9.0 FINDINGS AND RECOMMENDATIONS ................................................................................ 9-1

9.1 AOC-1 Benzene Impact to Ground Water Pathway, AC-03 .................................................... 9-1

9.2 AOC-2 Elevated PCB Concentrations in Soil at SB-02 and SB-04 .......................................... 9-1

9.3 AOC-3 Elevated PCB Concentrations in Soil at AC-01 ........................................................... 9-2

9.4 AOC-4 Historic Fill (Site-Wide) ............................................................................................... 9-2

9.5 AOC-5 Groundwater ................................................................................................................. 9-2

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TABLES

Table 1 AOC-1 – Historic Benzene Analytical Results Table 2 AOC-2/AOC-3 – Historic PCB Analytical Results Table 3 January 31, 2013 Groundwater Analytical Results Table 4 June 20, 2014 Sampling Activities and Laboratory Results Table 5 May 12, 2015 Post-Excavation Soil Sampling Activities and Laboratory Results Table 6 May 12, 2015 Soil Reuse Sampling Activities and Laboratory Results

FIGURES

Figure 1 Site Location Map Figure 2 Zoning Map Figure 3 Soils Map Figure 4 Historic Fill Map Figure 5 Wetlands Map Figure 6 FEMA FIRM Map Figure 7 Sample Location Map Figure 8 AOC Location Map Figure 9 Sensitive Populations Map Figure 10 Environmentally Sensitive Natural Resources Map Figure 11 Well Search Map Figure 12 Interim Remedial Measures Map

APPENDICES

Appendix A PCB Self-Implementing Cleanup and Disposal Plan Appendix B Receptor Evaluation Report Appendix C Public Notification Appendix D Test Pit and Soil Boring Logs Appendix E Laboratory Data Packages (CD only) Appendix F Quality Assurance Project Plan Appendix G Monitoring Well Certification and Well Decommissioning Forms Appendix H Disposal and Clean Fill Documentation Appendix I Historical Environmental Reports

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ACRONYMS

g/L micrograms per liter AOCs areas of concern CEA Classification Exception Area COCs contaminants of concern DHS Department of Human Services EDDs Electronic Data Deliverables EMA Environmental Management Associates, Inc.

EPA United States Environmental Protection Agency ESNR Environmentally Sensitive Natural Resource fbg feet below grade FEMA Federal Emergency Management Agency FIRM Flood Insurance Rate Map ft amsl feet above mean sea level GWQS Groundwater Quality Standards IGW SRS Impact to Ground Water Remediation Standard IGW SSL Impact to Groundwater Soil Screening Levels J OR an estimated value that exceeded the calibrated range of the instrument JD a diluted estimated value LSRP Licensed Site Remediation Professional MDLs method detection limits mg/kg milligrams per kilogram NJ New Jersey N.J.A.C. New Jersey Administrative Code NJDEP New Jersey Department of Environmental Protection NR-DCSRS Non-Residential Direct Contact Soil Remediation Standards O’Brien & Gere O’Brien & Gere Engineers, Inc.

PCBs polychlorinated biphenyls QAPP Quality Assurance Project Plan RAP remedial action permit RAR Remedial Action Report R-DCSRS Residential Direct Contact Soil Remediation Standards RE Receptor Evaluation RIR Remedial Investigation Report SIP Self-Implementing Cleanup and Disposal Plan SPLP synthetic precipitation leaching procedure SVOCs semi-volatile organic compounds TAL Target Analyte List TCL Target Compound List TCLP Toxicity Characteristic Leaching Procedure TSCA Toxic Substances Control Act TSS total suspended solids USACE United States Army Corps of Engineers Veolia Energy Veolia Energy Trenton, Inc.

VOCs volatile organic compounds Watermark Watermark Environmental, Inc.

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1.0 INTRODUCTION AND BACKGROUND

This Remedial Investigation Report (RIR)/Remedial Action Report (RAR) was prepared on behalf of the City of Trenton to address soil and groundwater contamination identified at the Lower Assunpink Creek Restoration Project. The project site is located at Block 105, Lot 1 (25 E. Lafayette Street) and Block 9503, Lot 4 (310 S. Warren Street), in the City of Trenton, New Jersey (NJ). The site is owned by the City of Trenton. Mr. Patrick G. Nocera is the Licensed Site Remediation Professional (LSRP) of record for the site.

A summary of remedial investigation activities conducted at the site between September 2010 and June 2015, as well as findings and conclusions of these investigations, are presented herein. Included with this RIR/RAR is a case inventory document, an executed New Jersey Department of Environmental Protection (NJDEP) Cover/Certification, RIR, Receptor Evaluation (RE), and Public Notification and Outreach forms. Electronic Data Deliverables (EDDs) are provided on included CD.

The regulatory timeframe to complete this RIR is December 8, 2016 for industrial establishments where the earliest applicable requirement to remediate occurred on or after March 2, 2010 with contaminants in soil and any other media. An Initial RE is being submitted with this RIR/RAR and is included in Appendix B. Notification and public outreach requirements were satisfied on September 23, 2014 via an environmental investigation/cleanup sign posted at the corner of E. Lafayette Street and S. Broad Street.

Proof of public notification is provided in Appendix C.

1.1 Project Location and Setting

The Lower Assunpink Creek Restoration Project occupies 2.63 acres in a densely populated, mixed-use area in downtown Trenton. The site is situated in an open grassy area adjacent to the six (6)-story State of New Jersey Department of Human Services (DHS) building at Capital Place One. The project site is bound by E. Lafayette Street to the north, S. Warren Street to the west, Assunpink Drive to the south, and S. Broad Street to the east. The site is currently vacant and unused. It is surrounded by a six (6)-foot high chain link fence and is generally inaccessible to the public.

The project site is bisected by a 500-foot section of the Lower Assunpink Creek where it is enclosed within a double-barreled buried concrete box culvert that runs east to west between S. Broad Street and S.

Warren Street. In September 2006, a section of the roof of the concrete culvert collapsed. Subsequent engineering investigations completed in 2007 revealed that the entire roof structure of the culvert, having been constructed over 30 years prior, was no longer stable and in imminent danger of further collapse.

In response to these events, the United States Army Corps of Engineers (USACE) proposed an environmental restoration project that would daylight the buried section of the Lower Assunpink Creek at the project site to address the public safety concern of the failed culvert and to restore the natural habitat of the Assunpink Creek ecosystem. In 2010 the City of Trenton entered into a Project Partnership Agreement with USACE to co-manage the design and execution of the project. The environmental restoration project includes the demolition of the concrete culvert that currently contains the 500-foot length of the Lower Assunpink Creek and the restoration of this section of the creek to a new open channel. Construction work is expected to begin in 2018 and is anticipated to last approximately 12-18 months.

Historically, the project site was the location of the earliest industrial and commercial activity in Trenton.

Many early industrial operations relying on the Creek for power were constructed over the Creek and along a small millrace located on the south side of the site along the current location of Assunpink Drive.

However, by the 1960’s, the entire area had fallen into ruin and the City acquired the properties that comprise the site to demolish and rebuild. All existing development was razed and the on-site soil was removed down to the underlying bedrock to allow for the construction of the subsurface concrete culvert in the mid 1970’s. An archaeological investigation conducted at the project site by Hunter Research, Inc.

in 2011 for the USACE indicates that little native undisturbed soil is left adjoining the Creek. Only in areas at the old millrace alongside Assunpink Creek (and outside the project area) may native soil be found. Based on these reports and the subsequent soil investigations reported here, the site is found to be

12030-00 Remedial Investigation/Remedial Action Report 1-2 November 2016 Broad Street Culvert Restoration Project, Trenton, NJ WLD2065 completely covered in historic fill to depths of 20 feet below grade (fbg).

Following construction of the culvert in the late 1970’s, Capital Place One and the six (6)-story DHS building were constructed. However, the 2.6 acres adjoining the Creek have remained undeveloped and unused.

The Trenton operations of Veolia Energy Trenton, Inc. (Veolia Energy) are located south of the site on property owned by the City of Trenton. Veolia Energy operates a network of thermal energy pipes in the immediate area that carry steam, hot water, and chilled water as part of a district heating and cooling system. A portion of this network of pipes currently cross the culvert in an area approximately 20 feet wide and 200 feet long that adjoins the Broad Street Bridge on the east portion of the Project site. The network of pipes is buried within loose media directly on top of the culvert that is covered with several feet of fill and turf.

1.2 Prior Environmental Investigations

In preparation for the design and construction of the environmental restoration project, environmental investigations were completed at the site in September 2010 and April-May 2011 by O’Brien & Gere Engineers, Inc. (O’Brien & Gere) as contractors to USACE. The findings of the September 2010 and April-May 2011 investigations are provided in the following reports and are included as appendices:

Geophysical, Geotechnical, and Environmental Investigation, Assunpink Restoration Project, Trenton, NJ, Environmental Investigation Report (January 2011).

Well Installation and Sampling, Assunpink Restoration Project, Trenton, NJ, Project Summary Report (August 2011).

The September 2010 investigation included the excavation of nine (9) test pits to depths ranging from nine (9) to 17 fbg and laboratory analyses of environmental soil samples collected during test pit excavation. The results and findings of the September 2010 investigation are listed below.

Logs of the test pit excavations indicate that the entire site in the areas that were excavated is covered by a layer of historic fill to depths ranging from the surface to six (6) – 17 fbg.

Laboratory analysis indicates that the fill layer is impacted by semi-volatile organic compounds (SVOCs), including benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, and dibenzo(a,h)anthracene, and metals, including lead, cadmium, and beryllium.

No exceedances of the NJDEP Residential Direct Contact Soil Remediation Standards (R- DCSRS) or Non-Residential Direct Contact Soil Remediation Standards (NR-DCSRS) for volatile organic compounds (VOCs), polychlorinated biphenyls (PCBs), or chlorinated pesticides and herbicides were identified in the environmental samples submitted for laboratory analysis.

One (1) exceedance for each of the NJDEP Impact to Groundwater Soil Screening Levels (IGW SSL) was reported for Dieldrin and Aroclor 1254 in analyses of site samples.

Waste characteristic analysis results indicate that site soils may be classified as non-hazardous.

Following receipt of the draft environmental report on the September 2010 investigation, the City of Trenton provided notification to NJDEP of the findings via the NJDEP “Hot Line” on December 8, 2010 and Case No. 101-208-095-948 was assigned.

Based on the results of the September 2010 investigation, additional investigation activities were conducted at the site in April-May 2011 to characterize the types of materials present adjacent to the stream culvert and to investigate groundwater quality at the interface to the creek.

Additional investigation activities were targeted to the location of a former service station that was previously operated at the southwest corner of the site near the intersection of S. Warren St. and Assunpink Drive. The former service station was identified on historical Sanborn Fire Insurance maps and operated circa the 1950s.

The April-May 2011 environmental investigation was completed by O’Brien & Gere as contractor’s to USACE. The following field tasks were completed:

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Four (4) overburden monitoring wells were installed including three (3) on the south side of the creek and one (1) on the north side of the creek. Well Certification Forms for these wells are included in Appendix G.

Five (5) soil borings were installed on the south side of the creek including three (3) in the southwest corner of the site at the location of the former service station.

Soil samples from the monitoring well boreholes (pilot borings) and soil borings, groundwater samples from the installed monitoring wells, and surface water samples for the creek were collected and submitted for laboratory analysis.

Groundwater levels were synoptically measured in the newly installed on-site wells.

All site work and deliverables were completed under the oversight of a New Jersey LSRP and in accordance with New Jersey Administrative Code (N.J.A.C.) 7:26E (“Technical Requirements for site Remediation”).

A summary of the laboratory analysis of soil, groundwater, and surface water samples is provided below.

Soil

VOC – No soil sample results exceeded the NR-DCSRS or the R-DCSRS. One (1) sample result for benzene exceeded the IGW SSL (identified as sample location AC-03).

SVOC – Sample results confirmed widespread impact consistent with Historic Fill and within NJDEP Historic Fill levels. One (1) exception is a sample result of naphthalene at 20 fbg that exceeded the R-DCSRS.

Pesticides/herbicides – No sample results exceeded the NR-DCSRS or the R-DCSRS. One (1) sample result for Dieldrin exceeded the IGW SSL.

PCBs – Sample results from two (2) test-boring locations (identified as SB-02 and SB-04) exceeded the NR-DCSRS, R-DCSRS, and IGW SSL.

Extractable petroleum hydrocarbons – No sample results exceeded the NJDEP screening level of 1,700 parts per million and no contingent analysis was performed.

Metals – Sample results reported exceedances of one (1) or more of the soil standards for the following metals: antimony, barium, beryllium, cadmium, lead, mercury, nickel, and thallium.

The results for beryllium, cadmium, and lead fall within the concentration ranges published in the Historic Fill Database.

Waste Characterization – All sample results indicate site soils may be classified as non-hazardous.

Groundwater

No sample results exceeded the NJDEP Groundwater Quality Standards (GWQS) for VOCs, SVOCs, pesticides/herbicides, or PCBs.

Metals – One (1) sample result exceeds the GWQS for lead. Exceedances of the GWQS for iron, manganese, and sodium were reported in samples collected from two (2) or more of the newly installed site wells.

Surface water

No results from the two (2) surface water samples collected from weep holes in the culvert walls indicated exceedances of the New Jersey Fresh Water Chronic Aquatic and Human Health criterion for VOCs, SVOCs, pesticides/herbicides, PCBs, and metals.

Based on the results of these investigations, five (5) areas of concern (AOCs) were identified at the site that required additional delineation and/or remedial action as documented in this RIR/RAR. The locations of the AOCs are depicted in Figure 8.

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AOC-1 – Benzene Impact to Ground Water Pathway at AC-03.

Benzene was detected above the IGW SSL of 0.005 milligrams per kilogram (mg/kg) at sample location AC-03 in soil samples collected on April 29, 2011. Benzene concentrations exceed the IGW SSL at depth intervals of 9 fbg (0.0942 mg/kg), 10.5 fbg (0.0445 mg/kg), and 11.2 fbg (0.0457 mg/kg). Historic benzene concentrations at AC-03 are summarized in Table 1.

AOC-2 – Elevated PCB Concentrations in Soil at SB-02 and SB-04

SB-02: PCBs were detected above the IGW SSL and R-DCSRS of 0.2 mg/kg and the NR-DCSRS of 1.0 mg/kg at sample location SB-02 in soil samples collected on April 26, 2011. PCB concentrations exceed the IGW SSL and R-DCSRS at depth intervals of 12.0-14.0 fbg (0.2297 mg/kg) and 19.5-20 fbg (0.864 mg/kg) and the IGW SSL, R-DCSRS, and NR-DCSRS at a depth interval 14.0-16.0 fbg (1.46 mg/kg).

Historic PCB concentrations at SB-02 are summarized in Table 2.

SB-04: PCBs were detected above the IGW SSL, R-DCSRS, and NR-DCSRS at sample location SB-04 in a soil sample collected on May 5, 2011 from a depth of 7.5-8.0 fbg (5.67 mg/kg). Historic PCB concentrations at SB-04 are summarized in Table 2.

In addition to NJDEP standards, PCBs also exceeded the Toxic Substances Control Act (TSCA) high occupancy limit of 1.0 mg/kg in AOC-2 at SB-02 (1.46 mg/kg, 14.0-16.0 fbg) and SB-04 (5.67 mg/kg, 7.5-8.0 fbg). As such, a PCB Self-Implementing Cleanup and Disposal Plan (SIP) was prepared for AOC-2 and was submitted to the United States Environmental Protection Agency (EPA) on February 23, 2015 (Appendix A). Total PCB concentrations were obtained by adding individual Aroclor values together. Only Aroclor constituents detected at concentrations exceeding specified method detection limits (MDLs) were considered for total PCB calculations. To date, all PCB remediation activities have been completed in accordance with all applicable local, state, and federal regulations.

AOC-3 – Elevated PCB Concentrations in Soil at AC-01

PCB concentrations exceeded the IGW SSL and R-DCSRS at sample location AC-01 (7.5-8.0 fbg) with a total concentration of 0.2527 mg/kg (Table 2). However, total PCB concentrations did not exceed the NR-DCSRS and no individual PCB isomer exceeded the NR-DCSRS, R-DCSRS, or IGW SSL.

Based on the fact that the site is, and will continue to be used for non-residential purposes, and that no potential groundwater receptors were identified at the site, no additional delineation was conducted in this AOC. However, any residual PCB impacts in this AOC will be addressed as part of the final remedial action to be completed at the site, as described in Section 9.0.

AOC-4 – Historic Fill (Site-Wide)

Previous investigations determined that historic fill material is present beneath a majority of the site and soil impacts associated with this fill material, including the presence of several SVOCs and metals at concentrations exceeding the NR-DCSRS, R-DCSRS, and/or IGW SSL have been delineated to the site boundaries. The presence of the fill material and related impacts will be addressed as part of the final remedial action to be completed at the site, as described in Section 9.0.

AOC-5 – Groundwater

The groundwater samples collected in the April-May 2011 site investigation found that no sample results exceeded the NJDEP GWQS for VOC, SVOC, pesticides/herbicides, or PCBs. One (1) sample result exceeded the GWQS for lead and exceedances of the GWQS for iron, manganese, and sodium were reported in samples collected from two (2) or more of the newly installed site wells.

Watermark Environmental, Inc. (Watermark) and its subcontractor, Arecon Ltd., were retained by the City of Trenton to compete all remedial investigation activities for all known contaminations at the five

(5) AOCs. These activities are listed below.

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Groundwater monitoring of the four (4) on-site wells in January 2013.

Delineation of the extent of PCB contamination and evaluate the benzene impact to ground water pathway in January 2014.

Interim remedial measures at AOC-2 (PCBs) in May 2015.

The results of these Remedial Investigations and Interim Remedial Actions conducted in January 2013 through May 2015 are provided herein.

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2.0 PHYSICAL SETTING AND GENERAL SITE DESCRIPTION

The Lower Assunpink Creek Restoration Project occupies 2.63 acres in a densely populated, mixed-use area in downtown Trenton. The site is situated in an open grassy area adjacent to the six (6)-story State of New Jersey DHS building at Capital Place One. The project site is bound by E. Lafayette Street to the north, S. Warren Street to the west, Assunpink Drive to the south, and S. Broad Street to the east. The site is currently vacant and unused. It is surrounded by a six (6)-foot high chain link fence and is generally inaccessible to the public. The overall topographic gradient in the vicinity of the site is generally towards the west. Figure 1 depicts the geographic location of the site on a United States Geological Survey 7.5 Minute Topographic Map (Trenton West).

2.1 Soils, Geology, and Hydrogeology

According to the United States Natural Resources Conservation Service Soil Survey for Mercer County, NJ, the surficial soils at the site consists of Urban Land, which mainly consists of impervious surfaces, including concrete, pavements, buildings, and other structures that are underlain by disturbed soil material. Figure 3 depicts the soil types identified on and in the vicinity of the site. During the June 20, 2014 sampling event, soils encountered consisted of historic fill including various proportions of sand and loam generally exhibiting a yellow-red hue. Soil boring logs are provided in Appendix D.

According to the NJDEP NJ-GeoWeb database, surficial geology throughout Block 105, Lot 1 (on the north side of the Assunpink Creek) consists primarily of Late Wisconsinan Glaciofluvial deposits.

Lithology for this geologic formation consists of yellowish brown to reddish brown sand and pebble-to-cobble size gravel with minor amounts of silt. Surficial geology throughout Block 9503, Lot 4 (on the south side of the Assunpink Creek) is primarily Alluvium, consisting of reddish brown, yellowish brown, brown, and gray sand, gravel, silt, minor clay, and peat. Where present at the site, these native soils were encountered underlying or mixed with historic fill material (see test pit and soil boring logs in Appendix D).

According to the New Jersey Geological Survey Historic Fill Map of the Trenton West Quadrangle, historic fill is present on the site. Figure 4 is a copy of a New Jersey Geological Survey Historic Fill Map of the Trenton West Quadrangle depicting the mapped extent of historic fill material on the site. The presence of historic fill material across a majority of the site was confirmed during the various environmental investigations conducted at the site, as documented in the test pit and soil boring logs included in Appendix D. Fill material noted throughout the site included brick, concrete, glass, ceramics, asphalt, cobbles, boulders, and disturbed soils. Fill material was encountered at various depths from the ground surface to a maximum depth of approximately 20 fbg. The fill material was underlain by native soils or bedrock.

The project summary report completed by O’Brien & Gere in August 2011 indicates that ground water on the south side of the site flows north-northwest to northwest towards Assunpink Creek. This was determined using depth to water measurements recorded from a ground water sampling event conducted on June 8, 2011. The project summary report also indicates that the direction of ground water flow on the north side of the site is likely south, also towards Assunpink Creek. This assumption is attributed to similar geology and elevations on both sides of the creek.

2.2 Surface Water

The Assunpink Creek extends through the center of the site, flowing east to west from the northeast corner to the southwest corner. The creek is currently contained within a concrete culvert located at the center of the site. The culvert is oriented at a lower elevation from the rest of the site, which features a grassy land cover gradually sloping toward the culvert.

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Review of the National Wetlands Inventory Maps did not identify any wetlands on the site. The Delaware River is located approximately 1,250 feet from the southwest corner of the site. Figure 5 is a copy of the National Wetlands Inventory Map for the area.

According to Federal Emergency Management Agency (FEMA) Flood Insurance Rate Map (FIRM) the site is in Zone A14, a 100-year Flood Hazard Area with determined flood elevations and flood hazard factors. A copy of the FIRM is included as Figure 6.

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3.0 CURRENT AND HISTORICAL USE INFORMATION

3.1 Target Site

The Lower Assunpink Creek Restoration Project occupies 2.63 acres in a densely populated, mixed-use area in downtown Trenton. The site is situated in an open grassy area adjacent to the six (6)-story State of New Jersey DHS building at Capital Place One. The project site is bound by E. Lafayette Street to the north, S. Warren Street to the west, Assunpink Drive to the south, and S. Broad Street to the east. The site is currently vacant and unused. It is surrounded by a six (6)-foot high chain link fence and is generally inaccessible to the public.

The project site is bisected by a 500-foot section of the Lower Assunpink Creek where it is enclosed within a double-barreled buried concrete box culvert that runs east-west between S. Broad Street and S.

Warren Street. In September 2006, a section of the roof of the concrete culvert collapsed. Subsequent engineering investigations completed in 2007 revealed that the entire roof structure of the culvert, having been constructed over 30 years prior, was no longer stable and in imminent danger of further collapse.

In response to these events, the USACE proposed an environmental restoration project that would daylight the buried section of the Lower Assunpink Creek at the project site to address the public safety concern of the failed culvert and to restore the natural habitat of the Assunpink Creek ecosystem. In 2010 the City of Trenton entered into a Project Partnership Agreement with USACE to co-manage the design and execution of the Project. The environmental restoration project includes the demolition of the concrete culvert that currently contains the 500-foot length of the Lower Assunpink Creek and the restoration of this section of the creek to a new open channel. Construction work is expected to begin in 2018 and is anticipated to last approximately 12-18 months.

Historically, the project site was the location of the earliest industrial and commercial activity in Trenton.

Many early industrial operations relying on the Creek for power were constructed over the Creek and along a small millrace located on the south side of the site along the current location of Assunpink Drive.

However, by the 1960’s, the entire area had fallen into ruin and the City acquired the properties that comprise the site to demolish and rebuild. All existing development was razed and the on-site soil was removed down to the underlying bedrock to allow for the construction of the subsurface concrete culvert in the mid 1970’s. An archaeological investigation conducted at the project site by Hunter Research, Inc.

in 2011 for the USACE indicates that little native undisturbed soil is left adjoining the Creek. Only in areas at the old millrace alongside Assunpink Creek (and outside the project area) may native soil be found. Based on these reports and the subsequent soil investigations reported here, the site is found to be completely covered in historic fill to depths of 14 fbg.

Following construction of the culvert in the late 1970’s, Capital Place One and the six (6)-story DHS building were constructed. However the 2.6 acres adjoining the Creek have remained undeveloped and unused.

The Trenton operations of Veolia Energy are located south of the site on property owned by the City of Trenton. Veolia Energy operates a network of thermal energy pipes in the immediate that carry steam, hot water, and chilled water as part of a district heating and cooling system. A portion of this network of pipes currently cross the culvert in an area approximately 20 feet wide and 200 feet long that adjoins the Broad Street Bridge on the east portion of the project site. The network of pipes is buried within loose media directly on top of the culvert which is covered with several feet of fill and turf.

Figure 9 is a Sensitive Populations Map depicting land use/land cover at the site. According to Figure 9, the property is listed as other urban/built-up land and commercial use, and no sensitive populations are shown on the map.

3.2 Surrounding Properties

The surrounding area includes a mix of residential, commercial, and government buildings. Mill Hill Park is located adjacent to the site, east of S. Broad Street. The Trenton operations of Veolia Energy are located south of the site on property owned by the City of Trenton.

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4.0 JANUARY 2013 GROUNDWATER MONITORING

On January 31, 2013, Watermark collected one (1) round of water levels (prior to purging activities) and groundwater samples from the four (4) existing on-site wells (AC-1, AC-2, AC-3, and AC-4) via low-flow sampling procedures in accordance with the NJDEP Field Sampling Procedures Manual. The four

(4) groundwater samples, one (1) trip blank, one (1) duplicate, and one (1) field blank were submitted to Chemtech, an NJDEP-certified laboratory (Laboratory ID # 20012), and analyzed for VOCs, SVOCs, PCBs, oil and grease, Target Analyte List (TAL) Metals, and total suspended solids (TSS). Laboratory data packages corresponding to the groundwater sampling event are included in Appendix E of this RIR/RAR and the results are summarized in Table 3.

Lead was detected in monitoring well AC-03 at a concentration of 9.2 micrograms per liter (g/L), which exceeds the GWQS of 3 g/L. Thallium was detected at an estimated concentration of 7.0 g/L in diluted sample AC-02, which is above the GWQS of 2 g/L. Pentachlorophenol was detected above the GWQS of 0.3 g/L in monitoring wells AC-01, AC-02, and AC-04 at concentrations of 0.59 g/L, 0.76 g/L, and

0.46 g/L, respectively. Concentrations of iron, manganese, and sodium were also detected above the GWQS in the groundwater samples.

Pentachlorophenol was detected in samples collected from monitoring wells AC-01, AC-02, and AC-04.

Pentachlorophenol was not detected above the applicable soil remediation standards; however, this constituent may be related to historic fill. Thallium was detected at a concentration of 0.064 J OR (an estimated value that exceeded the calibrated range of the instrument). The sample was diluted, and thallium was detected at a concentration of 7.0 JD (a diluted estimated value). If the thallium and pentachlorophenol concentrations in groundwater are determined to be related to historic fill, no further investigation will be required. A Classification Exception Area (CEA) will need to be established. A biennial certification and remedial action permit are not required when a CEA is established due to the presence of regional historic fill.

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5.0 JUNE 2014 REMEDIAL INVESTIGATION

Based on the results of the previous investigations conducted at the site, additional remedial investigation was performed at AOC-1 and AOC-2 to delineate the extent of PCB contamination and evaluate the benzene impact to ground water pathway. A Quality Assurance Project Plan (QAPP) containing sampling and analytical details is included as Appendix F.

5.1 Monitoring Well Decommissioning

On June 20, 2014, a NJDEP-certified driller [Environmental Management Associates, Inc. (EMA)] mobilized to the site to decommission the four (4) monitoring wells identified as AC-01, AC-02, AC-03, and AC-04. EMA personnel sealed the four (4) monitoring wells with concrete to properly decommission them. Forms documenting the closure of the monitoring wells are provided in Appendix G.

5.2 AOC-1 – Benzene Impact to Ground Water Pathway, AC-03

Benzene was detected above the IGW SSL of 0.005 mg/kg at sample location AC-03 in soil samples collected on April 29, 2011. Benzene concentrations exceed the IGW SSL at varying depth intervals from 9.0 to 11.2 fbg. A Monitoring Well Certification Form B prepared for monitoring well AC-03 installed at the AC-03 soil sample location indicates the ground elevation at that point to be 19.4 feet above mean sea level (ft amsl) and the inner casing of the monitoring well to be 22.17 ft amsl. A ground water sampling event conducted by O’Brien & Gere on May 23, 2011 determined the depth to ground water to be 10.62 feet below the top of the inner casing at monitoring well AC-03. Based on the elevation data presented in the Form B, depth to ground water as recorded from the sampling event was 7.85 fbg.

A copy of the Monitoring Well Certification Form B is included in Appendix G.

In accordance with the NJDEP “Technical Guidance for the Attainment of Remediation Standards and site-Specific Criteria” Version 1.0 dated September 24, 2012, contaminants of concern exceeding the impact to ground water exposure pathway need only be vertically and horizontally delineated if contamination occurs in the unsaturated or “vadose” zone. Since benzene concentrations exceeding the IGW SSL were detected in the zone of saturation located below the vadose zone, no further evaluation of the impact to ground water exposure pathway and/or delineation sampling is required at AOC-1.

5.3 AOC-2 – Elevated PCB Concentrations in Soil at SB-02 and SB-04

On June 20, 2014, PCB delineation soil samples were collected from the SB-02 and SB-04 sample locations. Prior to soil sample collection, sample locations were marked out and sample location coordinates were recorded using a global positioning system, as well as field measurements taken from stationary points throughout the site. The samples were field screened with a properly calibrated photoionization detector and soil-boring logs were completed for each sample location. A water level meter was used to determine the depth to ground water at the SB-02 soil boring location.

To effectively delineate the extent of PCB contamination at sample location SB-02, one (1) vertical delineation soil sample was collected from the original SB-02 sample location at a depth interval of 20 to 21 fbg. Due to poor recovery, only one (1) sample representative of the 21 to 24 fbg interval was collected. Brick and concrete fill material was encountered from four (4) to eight (8) fbg and 11 to 14.5 fbg and minor traces of brick fill material were encountered from 16 to 19 fbg. To horizontally delineate the extent of PCB contamination, due to refusal during the advancement of several attempted soil borings, a horizontal delineation sample could not be collected northwest of the SB-02 sample location. It is believed that a concrete slab or other solid mass used for the construction of the culvert was encountered.

Three (3) separate soil borings were attempted ranging from five (5) to 15 feet from SB-02 with refusal encountered at each location. To avoid potential damage to the culvert site, no soil boring was advanced and a sample was not collected. It should be noted that depth to water in the SB-02 boring was measured at 13.4 fbg.

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The delineation of SB-04 included the collection of samples from three (3) locations identified as SB-04- A, SB-04-B, and SB-04-C. One (1) sample was collected at the 7.5 to 8.0 fbg interval at each sample location with one (1) contingency sample collected from the 8.5 to 9.0 fbg interval at each location.

Sample locations were oriented in such a way that triangulates the initial SB-04 sample location. It should be noted that stones and red brick fragments were encountered at varying depths in all three (3) of the borings.

Samples were sent to Chemtech for analysis of PCBs. In addition to total PCBs, samples were analyzed for PCBs using the synthetic precipitation leaching procedure (SPLP) to develop a Site-Specific Impact to Ground Water Remediation Standard (IGW SRS) in compliance with the NJDEP “Development of Site- Specific Impact to Ground Water Soil Remediation Standards Using the Synthetic Precipitation Leaching Procedure” Version 3.0 dated November 2013. As detailed in Table 4, none of the samples exceeded the IGW SSL, R-DCSRS, or NR-DCSRS for PCBs; therefore, no contingency analysis was triggered.

Additionally, all SPLP samples were non-detect (MDL of 0.1 µg/L) for PCBs. Based on the laboratory results and based on the fact that the IGW SSL and the R-DCSRS for PCBs are the same value (0.2 mg/kg), the LSRP decided to use the IGW SSL as the Site-Specific IGW SRS for PCBs.

A sample location map depicting the June 20, 2014 sample locations is provided as Figure 7. Soil boring logs from the sampling event are included in Appendix D. Laboratory data packages corresponding to the sampling event are included in Appendix E of this RIR/RAR.

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6.0 RECEPTOR EVALUATION AND ECOLOGICAL EVALUATION

An Initial RE was prepared as part of the environmental investigation at the site. The purpose of the RE is to determine if there are any potential receptors located on or near the site and to document any actions taken to protect these receptors. This RE was prepared in accordance with N.J.A.C. 7:26E Technical Requirements for Site Remediation and the Receptor Evaluation Form Instructions (Version 2.2). Signed and completed New Jersey Department of Environmental Protection (NJDEP) Cover/Certification and RE Forms are included with this submittal.

Based on the results of the RE, sensitive populations were identified within 200 feet of the site and include parks/playgrounds located to the east and southwest. Figure 9 depicts the locations of the sensitive populations with respect to the site. Appendix B includes a table listing the addresses, owners, and site uses within a 200-foot radius. No evidence suggesting the contaminants of concern (COCs) identified at the site (benzene and PCBs) have impacted the surrounding sensitive populations has been noted. The interim remedial measures conducted at the site and the proposed remedial actions (including engineering and institutional controls) will ensure all exposure pathways are effectively minimized.

One (1) Environmentally Sensitive Natural Resource (ESNR), namely Assunpink Creek, is located on the site, as depicted in Figure 10. The portion of Assunpink Creek that flows through the center of the site is currently enclosed in a concrete culvert. The culvert acts as a buffer, eliminating the potential pathway to the creek. Furthermore, interim remedial measures have been completed at the site to remove the soils exhibiting the highest PCB concentrations in the area of SB-04, and upon completion of the proposed demolition of the culvert, the site is to be further remediated using engineering and institutional controls.

Additionally, on May 23, 2011, O’Brien & Gere collected two (2) surface water samples from Assunpink Creek from points located upstream and downstream on the site. The samples were analyzed for metals, pesticides, herbicides, PCBs, VOCs, SVOCs, oil, and grease. None of the samples exceeded respective NJ Fresh Water Human Health Criteria or NJ Fresh Water Chronic Aquatic Criteria. Based on these findings, no additional investigation is required into ESNRs at this time.

The City of Trenton, Department of Housing and Economic Development has confirmed that there are no land use changes planned within that radius.

Since it has been determined that ground water at the site has been impacted by the presence of historic fill material, a well search compliant with N.J.A.C 7:26E-1.14 was conducted. Using the NJDEP “XY Well Search for SRP Receptor Evaluation Requirements” database, potable wells identified within one (1) mile of the site were mapped, as depicted in Figure 11. Only one (1) potable well, domestic well ID 2700003487, was located within the 500-foot canvassing radius of the site. Further review indicated that the well is located on 12th Street in Ewing Township, approximately 2.25 miles from the site. To this end, it was concluded that the well coordinates were erroneously determined and that the well is not located within the 500-foot radius of concern. Additionally, all properties located within 500 feet of the site utilize city water. A well search spreadsheet in included in Appendix B to this RIR/RAR.

Based on the ground water analytical results, no ground water constituents exceed a respective Vapor Intrusion Ground Water Screening Level; therefore, the vapor intrusion pathway is not a concern at this time.

N.J.A.C. 7:26E-1.14(a)2.iv requires that community and non-community supply wells be sampled if ground water contamination is located in a Tier 1 Well Head Protection Area. According to the NJDEP’s NJ-GeoWeb database, the site is not located in a Tier 1 Community Well Head Protection Area. As such, no community or non-community supply wells have been sampled as part of this RE.

Based on the information provided in this RE, no potential receptors are being negatively impacted by the COCs identified at the site. Furthermore, the proposed remedial actions including engineering and institutional controls will ensure all exposure pathways are effectively minimized.

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7.0 INTERIM REMEDIAL MEASURES

Due to the proposed culvert demolition and creek daylighting activities taking place at the site within the vicinity of the SB-04 sample location, it was determined that PCB impacted soils at SB-04 would be excavated and disposed of off-site as in interim remedial measure. Vertical delineation sampling conducted at SB-04 in May 2011 and horizontal delineation sampling conducted in June 2014 indicated that PCB contamination was limited to 7.5-8.0 fbg and confined to the initial sample location. Using the horizontal delineation sample locations, the excavation footprint was determined to be a triangle approximately 36 ft. x 38 ft. x 42 ft. in size (Figure 12).

Remedial…