FINAL INDOOR AIR QUALITY REPORT #11. Former Raritan Arsenal

Transcription

1 FINAL INDOOR AIR QUALITY REPORT #11 Former Raritan Arsenal FUDS Project Number C02NJ February 2016 Prepared for: U.S. Army Corps of Engineers New England District Contract No. W912WJ-11-D-0002 Delivery Order 0005 Prepared by: A Service-Disabled Veteran Owned Small Business

2 Table of Contents SECTION TITLE PAGE 1. INTRODUCTION AND OBJECTIVES Regulatory Requirements and Agency Coordination Background Previous Reporting Groundwater AOCs Requiring No Further Action for Vapor Intrusion IAQ Report #7 Recommendations IAQ Report #8 Recommendations IAQ Report #9 Recommendations IAQ Report #10 Recommendations Vapor Migration Pathway USACE Indoor Air Evaluation Process METHODOLOGY Sampling Design Sampling Methods Groundwater Evaluation Subslab Soil Gas Sampling Method Building Survey Method Indoor Air Sampling Method Vapor Recovery Air Sampling Method Ambient Air Sampling Method Meteorological Data Quality Assurance/Control Sample Handling and Shipping Data Validation Procedures Available Screening Levels NJDEP Vapor Intrusion Screening Levels Site-Specific Screening Levels Screening Levels Used for Comparisons SAMPLING RESULTS FOR GROUNDWATER AOC Overview of Groundwater AOC Building Survey Subslab Soil Gas and Vapor Recovery System Indoor Air Meteorological Data Fieldcrest Avenue Prior Investigations i

3 Table of Contents, continued SECTION TITLE PAGE Current Investigation Subslab Soil Gas and Vapor Recovery System Results Indoor Air and Background Sampling Results Integrated Discussion of Results Conclusions and Recommendations Campus Plaza Prior Investigations Current Investigation Subslab Soil Gas Results Indoor Air and Background Sampling Results Integrated Discussion of Results Conclusions and Recommendations GROUNDWATER AOC Overview Fernwood Avenue Prior Investigations Current Investigation Conclusions and Recommendations SAMPLING RESULTS FOR GROUNDWATER AOC 8 A/B Overview of Groundwater AOC Building Survey Subslab Soil Gas Indoor Air Meteorological Data EPA Building Prior Investigations Current Investigation Subslab Soil Gas Results Indoor Air and Background Sampling Results Integrated Discussion of Results Conclusions and Recommendations EPA Building Prior Investigations Current Investigation Subslab Soil Gas Results Indoor Air and Background Sampling Results Integrated Discussion of Results Conclusions and Recommendations EPA Building ii

4 Table of Contents, continued SECTION TITLE PAGE Prior Investigations Current Investigation Subslab Soil Gas Sampling Results Indoor Air and Background Sampling Results Integrated Discussion of Results Conclusions and Recommendations EPA Building Prior Investigations Current Investigation Subslab Soil Gas Sampling Results Indoor Air and Background Sampling Results Integrated Discussion of Results Conclusions and Recommendations REFERENCES iii

5 Table of Contents, continued List of Appendices Appendix A 160 Fieldcrest Annual Report Appendix B Building 165 Workplan for Vapor Mitigation System and Monitoring Appendix C Campus Plaza 4 Historic Data Review Appendix D 102 Fernwood Avenue Annual Report Appendix E EPA Building 10 Optimization Study Appendix F Leak Test Results Appendix G Indoor Air Building Survey and Sampling Forms Appendix H Meteorological Data Appendix I Site-Specific Criteria Appendix J AOC 2 Historical Results Summary Appendix K Electronic Data Deliverables (on CD) Appendix L Laboratory Analytical Results and Data Validation Reports (on CD) Appendix M AOC 8 A/B Historical Results Summary List of Tables Table ES-1 Groundwater AOC 2 Sampling Result and Proposed Action Summary Table ES-2 Groundwater AOC 6 Sampling Result and Proposed Action Summary Table ES-3 Groundwater AOC 8 A/B Sampling Result and Proposed Action Summary Table 1-1 Status of Vapor Intrusion Concerns for Groundwater AOCs Table 1-2 List of Tenants and Addresses Table 2-1 Subslab Soil Gas Sample Location Summary Groundwater AOC 2 Table 2-2 Indoor Air Sample Location Summary Groundwater AOC 2 Table 2-3 Subslab Soil Gas Sample Location Summary Groundwater AOC 8 A/B Table 2-4 Indoor Air Sample Location Summary Groundwater AOC 8 A/B Table 2-5 AOC 2: Subslab Soil Gas Sampling Summary Table 2-6 AOC 8 A/B: Subslab Soil Gas Sampling Summary Table 2-7 AOC 2: Indoor Air Sampling Summary Table 2-8 AOC 8 A/B: Indoor Air Sampling Summary Table 2-9 Site-Specific Screening Levels Table 3-1 Contaminants of Potential Concern Groundwater AOC 2 Table 3-2 Subslab Soil Gas Analytical Results: September 2014 and March Fieldcrest: Groundwater AOC 2 Table 3-3 Vapor Recovery Analytical Results: September 2014 and March Fieldcrest: Groundwater AOC 2 Table 3-4 Subslab Soil Gas Analytical Results: September 2014 and January 2015 Campus Plaza 4: Groundwater AOC 2 Table 3-5 Indoor Air Analytical Results: September 2014 and March Fieldcrest: Groundwater AOC 2 Table 3-6 Indoor Air Analytical Results: September 2014 and January 2015 Campus Plaza 4: Groundwater AOC 2 iv

6 Table of Contents, continued Table 3-7 Meteorological Data Summary Groundwater AOC 2 Table Fieldcrest Avenue Sample Summary Table 3-9 Campus Plaza 4 Sample Summary Table 4-1 Contaminants of Potential Concern Groundwater AOC 6A Table 5-1 Contaminants of Potential Concern Groundwater AOC 8A/B Table 5-2 Subslab Soil Gas Analytical Results: September 2014 and January 2015 EPA Building 10: Groundwater AOC 8A/B Table 5-3 Subslab Soil Gas Analytical Results: September 2014 and January 2015 EPA Building 18: Groundwater AOC 8A/B Table 5-4 Subslab Soil Gas Analytical Results: September 2014 and January 2015 EPA Building 200: Groundwater AOC 8A/B Table 5-5 Subslab Soil Gas Analytical Results: September 2014 and January 2015 EPA Building 205: Groundwater AOC 8A/B Table 5-6 Indoor Air Analytical Results: September 2014 and January 2015 EPA Building 10: Groundwater AOC 8A/B Table 5-7 Indoor Air Analytical Results: September 2014 and January 2015 EPA Building 18: Groundwater AOC 8A/B Table 5-8 Indoor Air Analytical Results: September 2014 and January 2015 EPA Building 200: Groundwater AOC 8A/B Table 5-9 Indoor Air Analytical Results: September 2014 and January 2015 EPA Building 205: Groundwater AOC 8A/B Table 5-10 Meteorological Data Summary Groundwater AOC 8A/B Table 5-11 EPA Building 10 Sample Summary Table 5-12 EPA Building 18 Sample Summary Table 5-13 EPA Building 200 Sample Summary Table 5-14 EPA Building 205 Sample Summary List of Figures Figure ES-1 Indoor Air Program Overview Figure 1-1 Indoor Air Evaluation Approach Figure 3-1 PCE & TCE Results for Subslab Soil Gas and Indoor Air Samples, Building 165 Fieldcrest Figure 3-2 PCE & TCE Results for Subslab Soil Gas and Indoor Air Samples, Campus Plaza 4 Figure 4-1 PCE & TCE Results for Subslab Soil Gas and Indoor Air Samples, 102 Fernwood Avenue Figure 5-1 PCE & TCE Results for Subslab Soil Gas and Indoor Air Samples, EPA Building 10 Figure 5-2 PCE & TCE Results for Subslab Soil Gas and Indoor Air Samples, EPA Building 18 Figure 5-3 PCE & TCE Results for Subslab Soil Gas and Indoor Air Samples, EPA Building 200 v

7 Table of Contents, continued Figure 5-4 PCE & TCE Results for Subslab Soil Gas and Indoor Air Samples, EPA Building 205 Acronyms and Abbreviations AA AOC Avatar bgs CENAE CENAN CERCLA COPC CP cy DCA DCB DCE DERP DOD EDD EO EWMA EPA FBC FS ft FUDS GWQS GWRAWP IA IAQ LCD MCL MNA MSDS MTBE NAR NCP NJDEP NOAA NPL PCE ambient air area of concern Avatar Environmental, LLC below ground surface U.S. Army Corps of Engineers New England District U.S. Army Corps of Engineers New York District Comprehensive Environmental Response, Compensation, and Liability Act contaminant of potential concern Campus Plaza cubic yard dichloroethane dichlorobenzene dichloroethylene Defense Environmental Restoration Program Department of Defense Electronic Data Deliverable executive order Environmental Waste Management Associates U.S. Environmental Protection Agency Federal Business Center feasibility study feet Formerly Used Defense Site Groundwater Quality Standard Groundwater Remedial Action Work Plan indoor air indoor air quality Local Climatological Data Maximum Contaminant Level monitored natural attenuation material safety data sheet methyl tert-butyl ether Natural Attenuation Report National Contingency Plan New Jersey Department of Environmental Protection National Oceanic and Atmospheric Administration National Priorities List tetrachloroethylene vi

8 Table of Contents, continued QA QAPP QC RA RCP RD RI RPD SARA SOP SSD SSSG SSV SVE TCE UFP USACE USC UST VC VI VIG VR VOC Weston Quality Assurance Quality Assurance Project Plan Quality Control remedial action Raritan Center Parkway remedial design remedial investigation relative percent difference Superfund Amendments and Reauthorization Act standard operating procedure subslab depressurization subslab soil gas subslab venting soil vapor extraction trichloroethylene Uniform Federal Policy U.S. Army Corps of Engineers United States Code underground storage tank vinyl chloride vapor intrusion vapor intrusion guidance vapor recovery volatile organic compound Weston Solutions, Inc. vii

9 Executive Summary This focuses on the results from sampling events completed at the former Raritan Arsenal during September 2014 and January/March The report summarizes the recent results relative to prior sampling events. The following types of samples were collected: indoor air (IA), subslab soil gas (SSSG), vapor recovery (VR), and ambient air (AA). Buildings requiring ongoing investigation for vapor intrusion (VI) concerns based on prior results from groundwater and VI sampling were sampled for volatile organic compounds (VOCs). Figure ES-1 presents an overview of the VI sampling program at the former Raritan Arsenal. It depicts the various Groundwater Areas of Concern (AOCs) along with the buildings included in the sampling program. The primary site Contaminants of Potential Concern (COPCs) for the Groundwater AOCs have been determined by comparing the most recent groundwater sample results with groundwater screening levels that are protective of the VI pathway. Tetrachloroethylene (PCE), trichloroethylene (TCE), and vinyl chloride (VC) are the Groundwater AOC 2 COPCs (see Table 3-1). TCE is the COPC for Groundwater AOC 8 A/B (see Table 5-1). The analytical results for all sample types were evaluated collectively to determine whether the VI pathway is complete for each building, to make recommendations for future action(s) and where applicable, to determine if existing subslab vapor mitigation systems are operating effectively in removing contamination in subslab soil gas. The analytical results were compared with screening levels from the New Jersey Department of Environmental Protection (NJDEP) and site-specific screening levels developed by the U.S. Army Corps of Engineers (USACE). The recommendations for each building are described in the following paragraphs and presented in Tables ES-1 through ES-3. Groundwater AOC 2 ES-1

10 USACE continues to monitor three buildings within Groundwater AOC 2 for potential VI issues: 160 Fieldcrest, 165 Fieldcrest, and Campus Plaza 4. Two buildings (165 Fieldcrest and Campus Plaza 4) are sampled semi-annually. The third building (160 Fieldcrest) is sampled every 5 years with annual inspections of the subslab vapor mitigation system. Table ES-1 presents a summary of the recent sampling results along with proposed actions for Groundwater AOC Fieldcrest This building had a passive subslab vapor mitigation system installed in June Subsequent sampling has shown VOC concentrations in VR samples above soil gas screening levels. VOCs have not been observed in the indoor air. The absence of VOCs in indoor air illustrates that the VR system at 160 Fieldcrest is operating as designed. USACE performs an annual inspection of the subslab vapor mitigation system to ensure that the system is operating properly. Appendix A contains the most recent Remedial Action Progress Report (Geosyntec, 2015a) that presents a summary of the activities conducted between 6 November 2013 and 18 November 2014 and the system inspection conducted on 18 November It is recommended that system inspections continue on an annual basis to ensure the VR system continues to operate properly. The next analytical sampling round is scheduled for Fieldcrest The NJDEP installed a subslab depressurization (SSD) system at 165 Fieldcrest in August At that time, lines of evidence for vapor intrusion and building use factors led NJDEP to conclude that the VI pathway was possibly complete. Elevated levels of both TCE and PCE in groundwater in the immediate vicinity of the building, elevated levels of TCE and PCE in soil gas samples collected beneath the building, levels of PCE in indoor air, and the presence of a child care facility in the building were all factors leading to the decision to install the system. The data from the September 2014 and March 2015 sampling events for 165 Fieldcrest showed that the VI pathway is potentially complete but the detected concentrations are below levels of concern. Neither PCE nor TCE were detected in SSSG or IA at levels of concern even during the September 2014 sampling event when a portion of the SSD system was intentionally turned off. SSSG Results None of the SSSG sample results from the recent sampling for PCE and TCE were greater than the soil gas screening levels. The chloroform SSSG sample result from one location collected in September 2014 exceeded the NJDEP VIG nonresidential ES-2

11 soil gas screening level. The chloroform SSSG level in the March 2015 sample collected from the same location was less than the screening level. No other VOCs were detected in subslab soil gas at concentrations greater than the site-specific or the NJDEP VIG screening levels. VR Results There were no screening level exceedances in the VR samples collected during the September 2014 and March 2015 sampling events. IA Results The site COPCs (PCE, TCE, and VC) were not detected in the September 2014 IA samples even when a portion of the SSD system was turned off. TCE was detected in one IA sample collected in March PCE was detected at four locations in March All detected PCE and TCE concentrations were less than the screening levels. 1,2-Dichloroethane slightly exceeded its screening level at one location (165-5) in September Other VOCs detected in indoor air at concentrations above the NJDEP VIG screening levels included benzene, ethylbenzene, and chloroform. Benzene and ethylbenzene exceeded screening levels in September 2014 and March Chloroform exceeded screening levels in March 2015 only. The IA levels of these constituents were likely from an indoor source and not the VI pathway as demonstrated by the absence of these chemicals in the SSSG. USACE conducted an intentional, partial shutdown of the SSD system in August 2014 in advance of the planned September 2014 sampling event. The SSD system was turned off so that confirmation tests could be performed as part of the initial phase of the system closure plan. Upon completion of the September 2014 sampling event, the system was turned back on. USACE submitted a work plan (USACE, 2014) to NJDEP to seek concurrence on a protocol to allow for a full or partial SSD system shutdown at 165 Fieldcrest Avenue, such that the final evaluation phase of the soil vapor intrusion pathway may be completed. The next steps to be taken at 165 Fieldcrest are contingent on the results of a focused groundwater sampling event that was completed in August Appendix B contains the work plan and subsequent comments from NJDEP and responses from USACE. Campus Plaza 4 Campus Plaza 4 does not have a subslab vapor mitigation system. The results from the September 2014 and January 2015 sampling events are summarized by below. SSSG Results TCE concentrations in SSSG samples collected in September 2014 and January 2015 exceeded the nonresidential soil gas screening level at two of five sample locations. The recent TCE levels are similar to those that have been observed previously. No other site COPCs had SSSG levels greater than screening levels. ES-3

12 IA Results None of the site COPCs were detected in the IA samples collected during the September 2014 sampling event. The site COPCs were detected in the January 2015 samples but the concentrations were less than the nonresidential screening levels. Since TCE was detected in both soil gas and indoor air, a potentially complete exposure pathway exists at Campus Plaza 4, but the IA concentrations are not a concern. There has been a significant reduction in TCE levels in IA at Campus Plaza 4 when compared to previous sampling events. The previous TCE levels were due to a previous tenant s undocumented use of TCE. Since the departure of that tenant from Campus Plaza 4, TCE has not been an indoor air concern. The ambient ethylbenzene concentration from the September 2014 sampling event exceeded its nonresidential NJDEP screening level. USACE plans to reduce the frequency of subslab and indoor air sampling for Campus Plaza 4. The next sampling event is planned for winter 2016 at which time the data will be reevaluated, as will the determination of the need and frequency of future sampling events. In their comments to IAQ Report #10 (Avatar, 2014), NJDEP recommended implementation of remedial measures to address the VI pathway at Campus Plaza 4 in a letter dated November 6, This recommendation was based on NJDEP s assessment that the observed relationship among historical groundwater, soil gas and indoor air data indicates the presence of TCE in indoor air is due to vapor intrusion. A comprehensive review of the data, including a temporal trends analysis, collected from the building was performed and submitted to NJDEP in a letter dated April 20, 2015 (see Appendix C). This review concluded that the observed historical TCE exceedances are primarily attributable to background TCE sources inside the building from a former tenant rather than vapor intrusion. Consequently, it is USACE s position that the installation of a SSD system to mitigate VI is not required and that additional sampling at a reduced frequency will be performed. NJDEP responded to USACE s 20 April 2015 letter on 3 August 2015 (see Appendix C) and determined that the VI pathway cannot be completely ruled out and that continued monitoring at a reduced frequency is acceptable. Groundwater AOC 6 One building within AOC 6 ( Fernwood) is being monitored. USACE installed a subslab vapor mitigation system on October 2, 2009 to address VOCs in soil gas. The site COPCs (TCE ES-4

13 and vinyl chloride) were either non-detect or were detected at levels that were less than the nonresidential screening levels. In April 2011, PCE and TCE were detected in SSSG at concentrations greater than NJDEP VIG screening levels at the same sample location. However, neither TCE nor PCE were detected above NJDEP VIG screening levels for indoor air. This indicates that while TCE and PCE do not pose health risks in indoor air, the remaining concentrations of both constituents in soil gas should continue to be monitored (Table ES-2) The subslab vapor mitigation system was modified in March 2011 from an active (electric) system to solar powered system. Annual inspections of the subslab vapor mitigation system are performed to ensure that the system is operating properly (see Appendix D). USACE conducts a monthly visual inspection including measuring the vacuum at each vapor extraction point to verify the system is operating. USACE recommends annual inspection of the passive treatment system to ensure the system is properly functioning with sampling every 5 years. The next sampling round is scheduled for Groundwater AOC 8 A/B Four U.S. Environmental Protection Agency (EPA) buildings (Buildings 10, 18, 200, and 205) were sampled within Groundwater AOC 8 A/B during September 2014 and January Buildings 10, 200, and 205 have a subslab vapor mitigation system in place. Building 18 also has a subslab vapor mitigation system in place but the building has been vacant for years and the system has not been running. EPA reportedly has plans to reoccupy Building 18 in the future although the re-occupancy timeframe is unclear. Table ES-3 presents a summary of the recent sampling results along with proposed actions for Groundwater AOC 8. Building 10 VOCs have not been migrating into the indoor air from the subslab at levels of concern. This is due to the effectiveness of the subslab mitigation system. Semi-annual monitoring of the remedial system has demonstrated that the system is operating properly. SSSG Results TCE exceeded its nonresidential site-specific soil gas screening level in September 2014 at one location. The TCE levels in January 2015 were less than the ES-5

14 screening level. There were no other VOCs detected above the nonresidential screening levels that were sampled during the September 2014 and January 2015 sampling events at Building 10. IA Results During September 2014, TCE (10 µg/m 3 ) exceeded its nonresidential sitespecific screening level at one location. TCE was detected at 31 µg/m 3 at the paired soil gas sample location. The TCE IA level is about one-third of the level found in the SSSG. One would expect significantly more attenuation from the SSSG and a lower IA level based on the SSSG level that was observed if the TCE source was from the subslab. The empirical data suggest that the TCE exceedance in IA is indicative of an indoor source and not the VI pathway. Further, the TCE results from September 2014 from the other IA sample location were non-detect. TCE was non-detect in the January 2015 sample results. There were no other VOC concentrations detected in indoor air samples above the site-specific or NJDEP VIG screening levels. USACE recommends continuing semi-annual monitoring for another year at which time the data will be evaluated to determine the need for further sampling, frequency of sampling, and operation of the mitigation system. USACE performed an optimization study (Geosyntec, 2015c) of the mitigation system in May 2015 to determine the proper flow-rate and operation of the mitigation system and need for future sampling (see Appendix E). As a result of the optimization evaluation, a reduction in the SSD system operation is appropriate. There is a potential for fluctuations in the building pressure over time that could potentially result in intermittent, short-term TCE concentrations of concern. Therefore, ongoing operation at a reduced level is prudent. Of the three vents pipes that comprise the SSD system, SSD-2 has the greatest mass flux so it would be appropriate to focus SSD optimization efforts at SSD-2. It is recommended that the current SSD system be modified to operate with only extraction point SSD-2. NJDEP provided comments on the Building 10 optimization study on 14 July 2015 (see Appendix E). NJDEP indicated that the proposed modification to the SSD system is acceptable and provided recommendations regarding the next steps in the system optimization process. Building 18 This building was last sampled in September Following the September 2011 sampling event, the building was vacated and the utilities were turned off during the winter of USACE and NJDEP agreed to halt sampling as a result. Although no definitive plans exist, EPA reported that Building 18 could be re-occupied in the future. As such, USACE ES-6

15 collected samples from EPA Building 18 in September 2014 and January The results of the September 2014 and January 2015 sampling indicate that VOCs have not been migrating into the indoor air at concentrations of concern. SSSG Results TCE exceeded its nonresidential site-specific soil gas screening levels in September 2014 at three of four locations. TCE did not exceed its soil gas screening level in January There were no other VOCs detected above the nonresidential screening levels that were sampled during the September 2014 and January 2015 sampling events at Building 18. IA Results TCE was not detected in any of the IA samples collected in September 2014 and January There were no other VOC concentrations detected in indoor air samples above the site-specific or NJDEP VIG screening levels. USACE will consult with EPA to determine the future use plans for Building 18. If it is determined that Building 18 is planned for near-term future use, another round of semi-annual monitoring will be performed at which time the data will be evaluated to determine the need for further sampling. Building 200 Based on the analytical data from September 2014 and January 2015 which shows that while there were detections of TCE above nonresidential site-specific screening levels for subslab soil gas, it appears that levels of TCE in the indoor air were less than the nonresidential screening level. SSSG Results During September 2014 and January 2015, TCE concentrations were detected in soil gas above the nonresidential site-specific screening level. No other VOCs were detected above their screening levels for subslab soil gas. IA Results TCE was not detected in September The two locations sampled in January 2015 had detected TCE concentrations that were less than the site-specific nonresidential level. None of the other VOCs had concentrations detected above the nonresidential site-specific or the NJDEP VIG screening levels at the indoor air locations. The vapor intrusion pathway may be complete but the indoor air levels are not a concern. It is recommended that the monitoring continue at the same semi-annual frequency for the next year. USACE will evaluate the data to determine the optimum flow-rate and operation of the mitigation system and need for future sampling. This optimization study was performed in the summer of ES-7

16 Building 205 The results from the September 2014 and January 2015 sampling events are summarized by below. SSSG Results During the September 2014 and January 2015 sampling events, TCE was detected in all of the samples. However, TCE exceeded its site-specific nonresidential soil gas screening level at only one location. Additionally, chloroform was detected at a concentration above both the nonresidential NJDEP VIG screening levels at one location in September There were no other VOC concentrations detected above NJDEP VIG nonresidential screening levels in the subslab soil gas samples. IA Results TCE was not detected in any of the samples collected during September 2014 and January There were no other VOCs detected in indoor air samples above the site-specific or NJDEP VIG screening levels. The VI exposure pathway for TCE, the only COPC for AOC 8 A/B, is incomplete and successfully mitigated as demonstrated by the non-detect sample results in the IA samples. Continued semi-annual subslab and indoor air sampling of this building is recommended for the next year. USACE will evaluate the data to determine future sampling needs. Building 209 IAQ Report #10 (Avatar, 2014) recommended that no further sampling was needed at Building 209 due to a consistent lack of VOC concentrations in IA and SSSG greater than nonresidential screening levels. ES-8

17 FIGURES

18 Exclusion Area GS-SG-01 GS-01? (! 200-BG FERN 010-SG SG-02 Building SG SG-04? (?!! ( 010-BG VI pathway may need to be re-evaluated if the building use changes. AOC SG SG SG BG-01!?! (?!? (!?! ( k Building 10!! (?k (! k AOC8AB 205-SG ? (! SG-15!? ( 205-SG ? (! SG-12 k SAI Building 238? (! Building BG-01 Building 209 Building 150 Building SG !? ( k Home BG-01 Amax VR BG-01 Pepper BG-01 VR-02!? ) " 165-BG-01 k?celsis 04 Building 165! 165-5!? k165-3 (! (!! ( k (!! (!? 160-1! (!? ( Building 160! ( k!!!? ( STEEL-1!? CLAY MOL (Rnd1) (Roof) (Outside) (! "! ) (!?! ( (! k k 165-8(OutsideDC) AOC2 CP4-SG-3 CP4-BG-01 CP4-7 Building 427 CP4-1 CP4-4 CP4-5 (Campus!! ( Plaza 4!?!?! ( k!! (?!! ( CP4-6!?? (! CP4-SG-5 AOC9 Campus Plaza 5 CP4-2 CP4-SG-4 AOC8C CP4-SG-1 CP4-SG-2 CP4-SG-6 AOC8D Building 424 AOC7 Building 423 AOC7 AOC7 AOC4B AOC4A AOC1 102FERN FERN-SG FERN FERN-SG-03!? (! 102FERN FERN-SG-02 AOC10 102FERN-01! (? (! 102FERN-SG-01 Legend k Ambient Air Sample Locations ( Indoor Air Sample Locations!!? Subslab Soil Gas Sample Locations ) Vapor Recovery Sample Locations " Groundwater AOC Boundary Building With Suslab Vent Depressurization Building Screened Out of Investigation Based on Groundwater Data Building Requiring No Further Action Based on Soil Gas and Indoor Air Data Building With On-Going Monitoring Former Raritan Arsenal Boundary Exclusion Area DOD Source Removal Areas Area4 (Capped - not evaluated) Source: Aerial Photos from NJ Imagery on njwebmap.state.nj.us/ njimagery/natural dated Document Name: IAQ11_ES-1_Program-Overview_ FERN-SG-05!?! ( Building 102!? (! 102FERN FERN-05? (! k 102FERN-06 AOC6A AOC6C AOC6B µ Scale in Feet U.S. Army Corps of Engineers Former Raritan Arsenal Site, Edison, NJ 600 FIGURE ES-1 INDOOR AIR QUALITY PROGRAM OVERVIEW

19 Tables

20 Table ES-1 Groundwater AOC 2 Sampling Result and Proposed Action Summary IAQ Report #11 Former Raritan Arsenal Building Results Summary Proposed Action 160 Fieldcrest The subslab vapor mitigation system was inspected to determine that the system was working properly. A copy of the annual inspection report is located in Appendix A (Geosyntec, 2015a). A workplan was developed by USACE to seek NJDEP concurrence on a protocol to allow for a full or partial vapor mitigation system shutdown at 165 Fieldcrest Avenue, such that the final evaluation phase of the soil vapor intrusion pathway may be completed. The full report summarizing this information along with comments from NJDEP and responses from USACE can be found in Appendix B (USACE, 2014). Continue annual inspections of the subslab vapor mitigation system with 5-year sampling frequency. The next sampling event is scheduled for Fieldcrest SSSG Results None of the SSSG sample results from the recent sampling for PCE and TCE were greater than the soil gas screening levels. The chloroform SSSG sample result from one location collected in September 2014 exceeded the NJDEP VIG nonresidential soil gas screening level. The chloroform SSSG level in the March 2015 sample collected from the same location was less than the screening level. No other VOCs were detected in subslab soil gas at concentrations greater than the site-specific or the NJDEP VIG screening levels. VR Results There were no exceedances in the VR samples collected during the September 2014 and March 2015 sampling events. IA Results PCE and TCE were not detected in the September 2014 IA samples. Low levels of PCE and TCE were detected in March All detected PCE and TCE concentrations were less than the screening levels. 1,2- Dichloroethane slightly exceeded its screening level at one location in September Other VOCs detected in indoor air at concentrations above the screening levels included benzene, ethylbenzene, and chloroform. Benzene and ethylbenzene exceeded screening levels in September 2014 and March Chlorform exceeded screening levels in March 2015 only. USACE conducted an intentional, partial shutdown of the SSD system in August 2014 in advance of the planned September 2014 sampling event. The sample results from September 2014 for the AOC 2 COPCs were not a concern even during the partial shutdown. Upon completion of the September 2014 sampling event, the system was turned back on. USACE submitted a work plan (USACE, 2014) to NJDEP to seek concurrence on a protocol to allow for a full or partial SSD system shutdown at 165 Fieldcrest Avenue, such that the final evaluation phase of the soil vapor intrusion pathway may be completed (see Appendix B). The next steps to be taken at 165 Fieldcrest are based on the scenarios outlined in the workplan. Campus Plaza 4 SSSG Results - TCE concentrations in SSSG samples collected in September 2014 and January 2015 exceeded nonresidential site-specific soil gas screening levels at two of five sample locations. The recent TCE levels are similar to those that have been observed previously. No other site COPCs had SSSG levels greater than screening levels. Chloroform slightly exceeded its NJDEP screening level at a single location. IA Results - None of the site COPCs were detected in the IA samples collected during the September 2014 sampling event. PCE and TCE levels were detected in January 2015 but the levels were less than the nonresidential indoor air screening levels. There has been a significant reduction in TCE levels in IA when compared to previous sampling events. The previous TCE levels were due to a previous tenant s undocumented use of TCE. Since the departure of that tenant from Campus Plaza 4, TCE has not been an indoor air concern. USACE plans to reduce the sampling frequency. The next sampling event is planned for winter 2016 at which time the data will be reevaluated, as will the determination of the need and frequency of future sampling events. FUDS Project Number CO2NJ IAQ Report #11_ES Tables_Final 1 of 3 2/4/2016

21 Table ES-2 Groundwater AOC 6 Sampling Result and Proposed Action Summary IAQ Report #11 Former Raritan Arsenal Building Results Summary Proposed Action Fernwood The subslab vapor mitigation system was inspected at Fernwood and it was determined that the system was working properly. A copy of the annual inspection report is located in Appendix D (Geosyntec, 2015b). Continue annual inspections of the subslab vapor mitigation system with 5-year sampling frequency. USACE continues to conduct a monthly visual inspection including measuring the vacuum at each suction point to verify the system is operating. The next sampling event is scheduled for FUDS Project Number CO2NJ IAQ Report #11_ES Tables_Final 2 of 3 2/4/2016

22 Table ES-3 Groundwater AOC 8 Sampling Result and Proposed Action Summary IAQ Report #11 Former Raritan Arsenal Building Results Summary Proposed Action Building 10 SSSG Results - TCE exceeded site-specific soil gas screening level in September 2014 at one location. The TCE levels in January 2015 were less than screening levels. There were no other VOCs detected above the nonresidential screening levels during the September 2014 and January 2015 sampling events at Building 10. IA Results - During September 2014, TCE (10 µg/m 3 ) exceeded its nonresidential site-specific screening level at one location (010-3). TCE was detected at 31 µg/m 3 at the paired soil gas sample location. The TCE IA level is about one-third of the level found in the SSSG. One would expect significantly more attenuation and a ower IA level based on the SSSG levels that were observed if the TCE source was from the subslab. The empirical data suggest that the TCE exceedance in IA is indicative of an indoor source and not the VI pathway. Further, the TCE results from September 2014 from the other IA sample location were non-detect and TCE was non-detect in the January 2015 sample results. There were no other VOC concentrations detected in indoor air samples above the site-specific or NJDEP VIG screening levels. USACE recommends continuing semi-annual monitoring for another year (summer 2015 and winter 2016) at which time the data will be evaluated to determine the need for further sampling, frequency of sampling, and operation of the mitigation system. USACE performed an optimization study of the mitigation system in May 2015 and the results of the study along with comments from NJDEP can be found in Appendix E. Building 18 Building 200 SSSG Results - TCE exceeded its nonresidential site-specific soil gas screening levels in September 2014 at three of four sample locations. There were no other VOCs detected above the nonresidential screening levels that were sampled during the September 2014 and January 2015 sampling events at Building 18. IA Results - TCE was not detected in any of the IA samples collected in September 2014 and January There were no other VOC concentrations detected in indoor air samples above the site-specific or NJDEP VIG screening levels. SSSG Resuts - During September 2014 and January 2015, TCE concentrations were detected in soil gas above the nonresidential site-specific screening level. No other VOCs were detected above their screening levels for subslab soil gas. IA Results - TCE was either not detected or the detected levels were less than the site-specific nonresidential level. None of the other VOCs had concentrations detected above the nonresidential site-specific or the NJDEP VIG screening levels at the indoor air locations. USACE will consult with EPA to determine the future use plans for Building 18. If it is determined that Building 18 is planned for nearterm future use, another round of semi-annual monitoring will be performed at which time the data will be evaluated to determine the need for further sampling. It is recommended that the monitoring continue at the same semiannual frequency for the next year (summer 2015 and winter 2016). USACE will evaluate the data to determine the proper flow-rate and operation of the mitigation system and need for future sampling. This optimization study was performed in the summer of Building 205 Building 209 SSSG Results - During the September 2014 and January 2015 sampling events, TCE was detected in all of the samples. TCE exceeded its the site-specific nonresidential soil gas screening level at one location. Additionally, chloroform was detected at a concentration above the nonresidential NJDEP VIG screening level at one location in September There were no other VOC concentrations detected above NJDEP VIG nonresidential screening levels in the subslab soil gas samples. IA Results - TCE was not detected in any of the samples collected during September 2014 and January There were no other VOCs detected in indoor air samples above the site-specific or NJDEP VIG screening levels. Continued semi-annual subslab and indoor air sampling of this building is recommended for the next year (summer 2015 and winter 2016). USACE will evaluate the data to determine future sampling needs. Based on there being no site COPCs above the site-specific screening levels for a number of sampling rounds, the USACE recommended no further sampling at Building 209 in Indoor Air Quality Report #10 (Avatar, 2014). FUDS Project Number CO2NJ IAQ Report #11_ES Tables_Final 3 of 3 2/4/2016

23 Former Raritan Arsenal FUDS Project Number C02NJ INTRODUCTION AND OBJECTIVES Avatar Environmental, LLC (Avatar) evaluated the potential for vapor intrusion (VI) into buildings from contaminated groundwater at the former Raritan Arsenal site in Edison, NJ. This Indoor Air Quality (IAQ) Report #11 is a continuation of the ongoing IAQ monitoring program and was prepared for the U.S. Army Corps of Engineers (USACE) New York and New England Districts under USACE Contract W912WJ-11-D-0002, Delivery Order The objectives of this report are: To summarize and evaluate indoor air, subslab soil gas, and historical groundwater sampling results at each of the buildings recommended for sampling in Indoor Air Quality Report #10 (Avatar, 2014); To assess whether a complete VI exposure pathway exists; and To provide recommendations on the need for further action. This report presents the analytical results for buildings sampled during September 2014 and January/March 2015 within Groundwater Areas of Concern (AOCs) 2 and 8 A/B. These Groundwater AOCs have historically exhibited exceedances of the groundwater screening levels in the New Jersey Department of Environmental Protection s (NJDEP) Vapor Intrusion Guidance (VIG) (March 2013). Further, an update is provided in this report for work completed in Groundwater AOC 6. Table 1-1 provides a status of the vapor intrusion concerns for all of the Groundwater AOCs. As recommended in previous reports (Weston, 2006a, 2008a, and 2012), the buildings associated with Groundwater AOCs 4 and 10 do not require any further investigation or action and are not discussed in this report. 1.1 REGULATORY REQUIREMENTS AND AGENCY COORDINATION Activities at the former Raritan Arsenal are being administered by the USACE under the Defense Environmental Restoration Program/Formerly Used Defense Sites (DERP/FUDS) program. The Army is the executive agent on behalf of the Department of Defense (DOD) charged with meeting all applicable environmental restoration requirements at FUDS, regardless of which 1-1 February 2016

24 DOD branch previously owned or used the property. Former Raritan Arsenal FUDS Project Number C02NJ The Secretary of the Army further delegated the program management and execution responsibility for FUDS to the USACE. In carrying out its responsibilities, the USACE must comply with the DERP statute (10 USC 2701 et seq.), the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA, 42 USC 9601 et seq.), Executive Orders (EOs) and 13016, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), and all applicable DOD (e.g., DOD Management Guidance for the DERP) and Army policies in managing and executing the FUDS program. For FUDS properties not included on the National Priorities List (NPL), the DERP statute requires that response actions addressing DOD hazardous substances, pollutants, and contaminants be conducted in accordance with CERCLA. In all other cases, CERCLA is DOD s preferred framework for environmental restoration. States or tribes are generally the lead regulator for environmental investigations and responses at non-npl FUDS. DOD maintains lead agency authority at non-npl FUDS, coordinates project activities with the lead regulatory agency, and provides notice and opportunity for comment to the appropriate state, tribal, and local authorities. The former Raritan Arsenal property was identified as eligible for action under the FUDS program. The property is not on the NPL. Therefore, the NJDEP is the lead regulatory agency. Under the DERP-FUDS program, only known or potential contamination or hazards on the former Raritan Arsenal attributable to former DOD activities (prior to October 17, 1986) can be addressed. 1.2 BACKGROUND USACE is conducting various Remedial Investigation/Feasibility Study (RI/FS) and Remedial Design/Remedial Action (RD/RA) activities at the former Raritan Arsenal under DERP-FUDS. Through these activities, USACE and NJDEP identified Groundwater AOCs containing volatile organic compounds (VOC) that required evaluation for indoor air quality as presented in the Final Groundwater Natural Attenuation Report (NAR) dated May 2003 (Weston, 2003a) and in 1-2 February 2016

25 Former Raritan Arsenal FUDS Project Number C02NJ the IAQ Evaluation (Steps One through Four) (Weston, 2005a) and the Final Supplemental Groundwater Data Report (Weston, 2006b). In a March 2003 comment letter concerning the Draft Final Groundwater NAR (Weston, 2002), NJDEP agreed to natural attenuation as a means of addressing remaining groundwater contamination at the former Raritan Arsenal, provided no VI pathway existed in buildings located above the plumes. NJDEP requested USACE to evaluate potential vapor risks at 151 Fieldcrest Avenue, 165 Fieldcrest Avenue, and other buildings near monitoring well MW-114, which is considered to be a source well of chlorinated solvents located within Groundwater AOC 2 and historically has exhibited the highest detected concentrations of VOCs in groundwater at the former Raritan Arsenal. In May 2003, prior to the initiation of USACE s indoor air program, the property owner at 165 Fieldcrest conducted indoor air sampling that indicated the presence of tetrachloroethylene (PCE). Follow-up indoor air and subslab soil gas samples collected by USACE in June 2003 showed no PCE in indoor air, but did show PCE in the accompanying subslab soil gas samples. A subslab depressurization (SSD) system was subsequently installed jointly by USACE and NJDEP. This system is still in operation as of April As a result of the findings at 165 Fieldcrest, awareness of the potential for intrusion of VOCs from soil and/or groundwater into indoor air at the former Raritan Arsenal was heightened. The NJDEP requested that USACE evaluate the VI pathway for all other Groundwater AOCs at the former Raritan Arsenal. In October 2004, NJDEP agreed that assessment of the indoor air exposure pathway at the former Raritan Arsenal should be performed in accordance with the Approach for Evaluating Potential IAQ Impacts (USACE, 2004), referred to hereafter as The IAQ Approach. In accordance with The IAQ Approach, USACE began evaluating buildings located within 100 feet (ft) of the Groundwater AOCs. The Groundwater AOCs originally identified by USACE and NJDEP to be evaluated for IAQ were narrowed from seven to three since the primary contaminants of potential concern (COPCs) 1-3 February 2016

26 Former Raritan Arsenal FUDS Project Number C02NJ in groundwater are VOCs, mainly trichloroethylene (TCE) and PCE (see Table 1-1). Groundwater AOCs 2, 8, and 10 became the focus and were evaluated due to historical concentrations of VOCs in groundwater. In addition, Groundwater AOC 2 includes a building (165 Fieldcrest Avenue) with sensitive receptors (e.g., daycare center). Subsequent to the evaluation of Groundwater AOCs 2, 8, and 10, Groundwater AOCs 4 and 6 were evaluated for the potential of VI into indoor air in accordance with work plans developed in accordance with the NJDEP s VIG that was current at the time. Table 1-1 presents the VI status for all of the Groundwater AOCs Previous Reporting A series of IAQ reports have been developed over the past decade as part of the ongoing monitoring program. Each report discusses the buildings within the Groundwater AOCs that were evaluated and monitored along with the recommendations based on the analytical results for future action by USACE. The following is a list of the IAQ reports: IAQ Report (Weston, 2005b); IAQ Report #2, (Weston, 2006a); IAQ Report #3, (Weston, 2008a); IAQ Report #4, (Shaw [Shaw Environmental, Inc.], 2009); IAQ Report #5, (Shaw, 2010a); IAQ Report #6, (Shaw, 2010b); IAQ Report #7 (Weston, 2012); IAQ Report #8 (Weston, 2014b); IAQ Report #9 (Weston, 2014a); and IAQ Report #10 (Avatar, 2014). 1-4 February 2016

27 Former Raritan Arsenal FUDS Project Number C02NJ Groundwater AOCs Requiring No Further Action for Vapor Intrusion The recommendations from the previous IAQ reports have helped to focus the ongoing IAQ/VI monitoring program. No further action for VI was recommended for the three Groundwater AOCs listed below based on existing analytical data that were below levels of concern. Groundwater AOC 4 IAQ Report #3 (Weston, 2008a) recommended no further action at buildings within Groundwater AOC 4 based on existing groundwater, soil gas, and indoor air levels. NJDEP agreed with this recommendation. Groundwater AOC 6 IAQ Report #4 (Shaw, 2009) recommended no further action for all buildings within Groundwater AOC 6 except for Fernwood Avenue based on existing soil gas and indoor air levels. Installation of a vapor mitigation system was recommended for Fernwood along with monitoring on a 5 year frequency. Groundwater AOC 10 IAQ Report #2 (Weston, 2006a) recommended no further action was necessary at buildings within Groundwater AOC 10 due to insignificant levels of existing soil gas and indoor air levels. NJDEP agreed with this recommendation. Groundwater AOCs 1, 3, 5, and 7 require no further VI action because the groundwater contamination is not related to former DOD activities. Lastly, there are no volatile contaminants associated with AOC 9. Therefore, there are no VI concerns for AOC IAQ Report #7 Recommendations The following are the recommendations from IAQ Report #7 based on the sampling activities conducted during September 2010 and April 2011 by Groundwater AOC: Groundwater AOC Fieldcrest Avenue Continue annual inspection of the vapor mitigation system with a 5-year sampling frequency for indoor air and subslab soil gas. The next sampling round scheduled for Fieldcrest Avenue Continue semi-annual sampling to monitor and confirm that the vapor mitigation system is operating effectively. Campus Plaza 4 Continue semi-annual sampling to evaluate the potential for the VI pathway. 1-5 February 2016

28 Former Raritan Arsenal FUDS Project Number C02NJ Groundwater AOC Fernwood Avenue Perform passive sampling of the mitigation system only and submit results in a separate Interim Progress Report and Performance Monitoring Report for the subslab venting system. Groundwater AOC 8 A/B Building 10 Continue semi-annual sampling with an emphasis on ensuring the subslab system is operating properly. Building 18 Continue semi-annual sampling with an emphasis on ensuring the subslab system is operating properly. Building 200 Continue semi-annual sampling with an emphasis on ensuring the subslab system is operating properly. Building 205 Continue semi-annual sampling with an emphasis on ensuring the subslab system is operating properly. Building 209 Continue semi-annual sampling IAQ Report #8 Recommendations The following are the recommendations of IAQ Report #8 (Weston, 2014b) based on sampling activities performed during September 2011 and April 2012 by Groundwater AOC: Groundwater AOC Fieldcrest Continue annual inspections of the vapor mitigation system with 5- year sampling frequency. Last sampling event was conducted in November 2011 and next sampling event is scheduled for Fieldcrest Continued monitoring for the next year (summer 2012 and winter 2013) is recommended to monitor the effectiveness of the subslab mitigation system. USACE takes ownership of the vapor mitigation system beginning in February Additionally, USACE will begin evaluations for potential modifications to the vapor mitigation system beginning in Campus Plaza 4 Since there is a potential for a complete exposure pathway from groundwater to soil gas to indoor air, continued monitoring for this building was recommended. USACE will continue to monitor both subslab and indoor air semiannually (summer 2012 and winter 2013) and then re-evaluate. Additionally, a separate study will be conducted in 2013 to investigate likely sources of indoor air 1-6 February 2016

29 Groundwater AOC 6 Former Raritan Arsenal FUDS Project Number C02NJ contaminants using isotopes to distinguish between indoor air sources and subslab sources Fernwood Avenue Continue annual inspections of the vapor mitigation system with 5-year sampling frequency. Last sampling event was conducted in June 2012 and next sampling event is scheduled for Continue monthly visual inspection of subslab system by USACE including vacuum checks. Groundwater AOC 8 A/B Building 10 Although there is not a complete exposure pathway, continued semiannual monitoring was recommended (summer 2012 and winter 2013) to confirm proper operation of the mitigation system. After a year, the data will be evaluated to determine sampling needs, sampling frequency, and if continued operation of the system is necessary. Building 18 Sample results from this investigation do not indicate a complete VI pathway. Since the building is no longer in use and has been vacated, USACE and NJDEP agreed that monitoring will not continue. Building 200 USACE will continue to monitor both subslab and indoor air semiannually over the next year (summer 2012 and winter 2013). After a year, the data will be evaluated to determine sampling needs, sampling frequency, and if continued operation of the system is necessary. Continue monthly inspection of subslab system including vacuum and velocity checks to ensure system is working. Building 205 Continued semi-annual subslab and indoor air sampling of this building is recommended for the next year (summer 2012 and winter 2013). After a year, the data will be evaluated to determine sampling needs, sampling frequency, and if continued operation of the system is necessary. Building 209 Although there is not a complete exposure pathway, continued semiannual monitoring of this building is recommended for the next year (summer 2012 and winter 2013). After a year, the data will be evaluated to determine sampling needs, sampling frequency, and if continued operation of the system is necessary IAQ Report #9 Recommendations The following are the recommendations of IAQ Report #9 (Weston, 2014a) based on sampling activities conducted during October 2012 and February 2013 by Groundwater AOC: Groundwater AOC February 2016

30 Former Raritan Arsenal FUDS Project Number C02NJ Fieldcrest Continue annual inspections of the vapor mitigation system with 5- year sampling frequency. Last sampling event was conducted in November 2011 and next sampling event is scheduled for Fieldcrest Continued monitoring for the next year (summer 2013 and winter 2014) is recommended to monitor the effectiveness of the subslab mitigation system. USACE will continue evaluations for potential modifications to the vapor mitigation system that began in Campus Plaza 4 Continued monitoring for this building is recommended (summer 2013 and winter 2014) and then re-evaluate. Groundwater AOC Fernwood Avenue Continue annual inspections of the vapor mitigation system with 5-year sampling frequency. Last sampling event was conducted in June 2012 and next sampling event is scheduled for Continue monthly visual inspection of subslab system by USACE including vacuum checks. Groundwater AOC 8 A/B Building 10 Although there is not a complete exposure pathway, continued semiannual monitoring is recommended (summer 2013 and winter 2014) to confirm proper operation of the mitigation system. After a year, the data will be evaluated to determine sampling needs, sampling frequency, and if continued operation of the system is necessary. Building 200 USACE will continue to monitor both subslab and indoor air semiannually over the next year (summer 2013 and winter 2014). After a year, the data will be evaluated to determine sampling needs, sampling frequency, and if continued operation of the system is necessary. Building 205 Continued semi-annual subslab and indoor air sampling of this building is recommended for the next year (summer 2013 and winter 2014). The vapor mitigation system for Building 205 will be evaluated for system optimization. Building 209 USACE recommended no further sampling at this building based on an incomplete pathway from groundwater to SSSG IAQ Report #10 Recommendations The following are the recommendations of IAQ Report #10 (Avatar, 2014) based on sampling activities conducted during September/October 2013 and February 2014 by Groundwater AOC: Groundwater AOC February 2016

31 Former Raritan Arsenal FUDS Project Number C02NJ Fieldcrest Continue annual inspections of the vapor mitigation system with 5- year sampling frequency. Continue monthly visual inspection of subslab system by USACE including vacuum checks. Last sampling event was conducted in November 2011 and next sampling event is scheduled for Fieldcrest Continued monitoring for the next year (summer 2014 and winter 2015) is recommended to monitor the effectiveness of the subslab mitigation system. USACE will continue evaluations for potential modifications to the vapor mitigation system that began in USACE conducted a partial shutdown of the SSD system in August 2014 in advance of the planned September 2014 sampling event. Upon completion of the September 2014 sampling event, the system was turned back on. USACE and NJDEP are discussing the conditions for system termination. If the data collected in September 2014 and winter 2015 indicate that operation of the SSD is necessary, it is recommended to replace the current SSD blowers with radon fans, which are smaller and more energy efficient. Campus Plaza 4 Continued monitoring for this building is recommended (summer 2014 and winter 2015) and then re-evaluate. Groundwater AOC Fernwood Avenue Continue annual inspections of the vapor mitigation system with 5-year sampling frequency. Last sampling event was conducted in June 2012 and next sampling event is scheduled for Groundwater AOC 8 A/B Building 10 Although there is not a complete exposure pathway, continued semiannual monitoring is recommended (summer 2014 and winter 2015) to confirm proper operation of the mitigation system. After a year, the data will be evaluated to determine sampling needs, sampling frequency, and if continued operation of the system is necessary. USACE will also perform an optimization study of the mitigation system to determine the proper flow-rate and operation of the mitigation system and need for future sampling. Building 18 This building is not discussed in IAQ Report #10 because it has been vacant and was not sampled in summer 2013 or winter EPA reportedly has plans to re-occupy Building 18 at some point in the future. As a result, Building 18 was planned to be sampled in summer 2014 and winter Building 200 USACE will continue to monitor both subslab and indoor air semiannually over the next year (summer 2014 and winter 2015). After a year, the data will be evaluated to determine sampling needs, sampling frequency, and if continued operation of the system is necessary. 1-9 February 2016

32 Former Raritan Arsenal FUDS Project Number C02NJ Building 205 Continued semi-annual subslab and indoor air sampling of this building is recommended for the next year (summer 2014 and winter 2015). The vapor mitigation system for Building 205 will be evaluated for system optimization. Building 209 USACE recommended no further sampling at this building based on an incomplete pathway from groundwater to SSSG. This report (IAQ Report #11) presents the findings of investigations conducted during the period of September 2014 and January/March Table 1-2 summarizes the buildings and tenants included in the investigation described in this report. 1.3 VAPOR MIGRATION PATHWAY This report evaluates the potential migration pathway of VOCs from groundwater and soils to indoor air. Due to their high vapor pressures, VOCs dissolved in groundwater readily volatilize from the groundwater and move by diffusion and advection (which is actually the more dominant mechanism) through the capillary and unsaturated zones of the soil, eventually discharging to the atmosphere at the ground surface. Lateral and vertical migration of soil gas occurs in response to variations in pressure and can be quite complex. For example, high-pressure weather systems tend to keep soil gas in the subsurface, while low pressure weather systems allow the soil gas to move readily into the atmosphere. Variations in soil texture and permeability greatly affect the movement of soil gas, as do the presence of underground utilities and other structures that may act as conduits. In areas where the ground surface is covered by a building or paved surface, VOCs in soil gas can become trapped beneath these structures resulting in a mounding effect. These vapors are capable of entering structures through minute cracks in foundations, pipe, or utility penetrations through the concrete floor slabs or walls, and through foundation drains. Soil gas entry into structures is usually the result of pressure differentials which are mainly caused by indoor-outdoor thermal differences, wind loading on structures, and unbalanced ventilation systems that can result in the depressurization of a building (Hodgson, et al. 1992). Most buildings maintain an indoor air pressure that is often lower than outdoor air. Under this negative pressure, subsurface soil gas may be drawn to cracks in the basement or slab floor and 1-10 February 2016

33 Former Raritan Arsenal FUDS Project Number C02NJ into the building. A building in this situation has an area of influence which may draw subsurface soil gas toward the building slab from surrounding areas. Many factors influence the rate of soil gas entry into a building at any given time. Increased soil moisture, which often occurs in the spring after the ground thaws and snow melts, can drive soil gas from surrounding areas into the relatively dry soils beneath structures, increasing the potential for vapor infiltration. Heavy rainfall can also result in a lens/layer of clean water at the water table reducing the source soil gas concentrations. Frozen ground can also limit the vertical migration of subsurface gases and increase mounding effects and lateral migration. Under heating conditions, building basements or the first floor above the concrete slab can be under less pressure relative to the surrounding soil (Hodgson, et al. 1992). This is sometimes referred to as the stack or chimney effect, and can greatly increase the rate of soil gas infiltration. For the above reasons, winter and spring conditions tend to promote the infiltration of soil gas into structures and generally represent worst-case conditions. As indicated in Section of the NJDEP VIG (2013), indoor air samples collected from November through March are required prior to making remedial decisions as this timeframe is considered as being most representative of the presumed worst case conditions. 1.4 USACE INDOOR AIR EVALUATION PROCESS The IAQ Approach for the former Raritan Arsenal establishes the priorities for further investigation of potential IAQ impacts (Figure 1-1). The IAQ Approach, which has been agreed to by the NJDEP, is a step-wise approach to evaluate the potential for IAQ impacts from contaminated groundwater and residual soil sources at the former Raritan Arsenal. Steps One through Four of the IAQ Approach are: Step One: Complete preliminary inventory of buildings potentially affected by Groundwater AOC plumes. Step Two: Develop a conceptual model for each Groundwater AOC plume. Step Three: Determine contaminants of potential concern (COPC) for further evaluation by comparing historical groundwater data to Table 2C-GW screening 1-11 February 2016

34 Former Raritan Arsenal FUDS Project Number C02NJ benchmarks from the Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils (EPA, 2002). Step Four: Prioritize Groundwater AOC plumes to be evaluated for potential VI based on sensitive receptors and historical groundwater data. Expedite an evaluation process where groundwater concentrations are 50 times greater than Table 2C-GW screening benchmarks. It should be noted that going forward, the decision process set forth in the NJDEP VIG will be used to determine the need for expedited review of the potential for VI at the former Raritan Arsenal, if specific Groundwater AOCs and the buildings associated with those AOCs have not yet been evaluated. The information gathered under Steps One through Four provide a basis for Steps Five through Twelve of the IAQ Approach. Step Five: Using existing groundwater quality data, assess whether there is potential for a complete VI pathway from groundwater to indoor air and evaluate the potential IAQ impacts. If groundwater data indicate the potential for VI concerns (i.e., exceed screening criteria), then go to Step Six. Step Six: Conduct subslab soil gas sampling. Step Seven: Compare soil gas concentrations to the subslab soil gas screening benchmarks. Predict concentrations of VOCs in indoor air based on subslab soil gas data. If soil gas data indicate potential exceedance of residential indoor air screening benchmarks, then go to Step Eight. While The IAQ Approach originally required comparison of site-specific data to the EPA Generic Screening Benchmarks for Target Indoor Air Concentrations (EPA Table 2C [EPA, 2002]) criteria, this approach was developed prior to publication of the NJDEP VIG. Moving forward, site-specific data have been, and will continue to be, compared with the most recent screening levels provided in the NJDEP VIG and site-specific risk-based screening levels for select COPCs (see Appendix I). Step Eight: Evaluate indoor air impacts by conducting sampling to determine if indoor VOC concentrations exceed ambient air sample results and/or residential indoor air limits. Identify other buildings for soil gas sampling. Step Nine: Perform confirmatory sampling of subslab soil gas and indoor air at the building (to assess temporal variability and verify the initial findings). Step Ten: If the confirmatory sampling verifies the initial results, evaluate remedial alternatives for the building. Step Eleven: Implement remedy for the building and collect post-remedial indoor air and subslab soil gas samples to document system effectiveness February 2016

35 Former Raritan Arsenal FUDS Project Number C02NJ Step Twelve: Prepare report documenting process and results for the NJDEP February 2016

36 FIGURES

37