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Si o z \ vw * PRCf^ FINAL Military Munitions Response Program Record of Decision Aberdeen Proving Ground - Aberdeen Area Munitions Response Sites April 2023 U.S. Army Garrison Aberdeen Proving Ground, Maryland ------- FINAL Military Munitions Response Program Record of Decision Aberdeen Proving Ground - Aberdeen Area Munitions Response Sites U.S. Army Garrison Aberdeen Proving Ground, Maryland Contract W56ZTN-17-D-0011, Task Order W56ZTN20F0097 April 2022 Prepared for: U.S. Army Environmental Command 2450 Connell Road Fort Sam Houston, Texas 78234-7664 U.S. Army Garrison Aberdeen Proving Ground E5183 Blackhawk Rd Gunpowder, Maryland 21010 Prepared by: _3?SUNDANCE-EA II, LLC Sundance-EA LLC 1311 Continental Drive, Suite K Abingdon, Maryland 21009 ------- Page i April 2023 Table of Contents 1.0 DECLARATION 1 1.1 Site Name and Location 1 1.2 Statement of Basis and Purpose 1 1.3 Assessment of Site 1 1.4 Description of Selected Remedy 2 1.5 Statutory Determinations 2 1.5.1 Part 1: Statutory Requirements 2 1.5.2 Part 2: Statutory Preference for Treatment 5 1.5.3 Part 3: Five-Year Review Requirement 5 1.6 Record of Decision Data Certification Checklist 5 1.7 Authorizing Signatures 6 2.0 DECISION SUMMARY 7 2.1 Site Name, Location, and Description 7 2.2 Site History and Enforcement Activities 8 2.3 Community Participation 9 2.4 Scope and Role of Munitions Response Site Response Action 10 2.5 Site Characteristics 10 2.5.1 Facility Profile 10 2.5.2 Physical Profile 13 2.5.3 Land Use Profile 15 2.5.4 Ecological Profile 15 2.5.5 Nature and Extent of MEC/MC Release Profile 16 2.6 Current and Potential Future Land Use and Resource Uses 19 2.6.1 Land Use 19 2.6.2 Groundwater and Surface Water Uses 20 2.7 Summary of Site Risks 20 2.7.1 MC Risk Assessment 20 2.7.2 MEC Concern Hazard Assessment 23 2.7.3 Basis for Taking Action 24 2.8 Remedial Action Objectives 24 2.9 Description of Alternatives 25 2.9.1 Alternative 1—No Action 25 2.9.2 Alternative 2—Land Use Controls for the MPR and FDA MRSs 25 2.10 Comparative Analysis of Alternatives 26 2.10.1 Threshold Criteria 28 2.10.2 Balancing Criteria 28 2.10.3 Modifying Criteria 30 2.11 Principal Threat Wastes 30 2.12 Selected Remedy 30 2.12.1 Summary of the Rationale for the Selected Remedy 31 2.12.2 Description of Selected Remedy 31 2.12.3 Annual Inspections 34 2.12.4 Comprehensive Environmental Response, Compensation, and Liability Act Five- Year Reviews 34 2.12.5 Summary of Estimated Remedy Costs 35 2.12.6 Expected Outcomes of Selected Remedy 35 Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page ii April 2023 2.12.7 Green Remediation 36 2.12.8 Remedial Design 36 2.13 Statutory Determinations 36 2.13.1 Protection of Human Health and the Environment 37 2.13.2 Compliance with Applicable or Relevant and Appropriate Requirements 37 2.13.3 Cost Effectiveness 37 2.13.4 Utilization of Permanent Solutions and Alternative Treatment Technologies to the Maximum Extent Practicable 37 2.13.5 Preference forTreatment as a Principal Element 38 2.13.6 Five-Year Review Requirements 38 2.14 Documentation of Significant Changes 38 3.0 RESPONSIVENESS SUM MARY 39 3.1 Stakeholder Comments and Lead Agency Responses 39 3.2 Technical and Legal Issues 39 4.0 REFERENCES 40 1. Version: 1.0 1 Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page iii April 2023 List of Figures Figure 1. Site Location 3 Figure 2. Munitions Response Sites 4 Figure 3. MEC Conceptual Site Model 12 Figure 4. Munitions Response Sites LUC Boundaries 33 List of Tables Table 1. List of APG-AA MRSs Addressed in this ROD 1 Table 2. Record of Decision Data Certification Checklist 5 Table3. MMRP Activity Timeline 8 Table 4. Public Notification of Document Availability 9 Table 5. Public Comment Period Requirements 9 Table 6. MPR and FDA MRS Remedial Action Alternatives 25 Table 7. Evaluation Criteria for Superfund Remedial Alternatives 27 Table 8. Comparative Analysis of Remediation Alternatives 28 Table 9. Summary of ARARs for the MPR and FDA MRSs 29 Table 10. Summary of Costs 30 List of Appendices Appendix A MDE Letters of Concurrence (To be provided in Final Document) Appendix B Affidavits for Public Notice Appendix C Cost Summary Appendix D Summary of Comments Received During Public Comment Period and Army Responses Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page iv April 2023 Acronyms and Abbreviations |jg/L Micrograms per liter % Percent § Section °F Degrees Fahrenheit AA Aberdeen Area AP Armor-piercing APG Aberdeen Proving Ground ARAR Applicable or relevant and appropriate requirement Army U.S. Army bgs Below ground surface BMP Best management practice BRAC Base Realignment and Closure CAIS Chemical agent identification sets CERCLA Comprehensive Environmental Response, Compensation, and Liability Act CFR Code of Federal Regulations COMAR Code of Maryland Regulations COPC Contaminant of potential concern COPEC Contaminant of potential ecological concern CRP Community relations plan CSM Conceptual site model DERP Defense Environmental Restoration Program DGM Digital geophysical mapping DoD Department of Defense EA EA Engineering, Science, and Technology, Inc. EOD Explosive ordnance disposal ERT ERT, Inc. EUL Enhanced use lease FDA Former Demolition Area FS Feasibility study ft Feet or foot GIS Geographic information system HA Hazard assessment HE High explosive HEI-T High-explosive incendiary with tracer HHRA Human health risk assessment HI Hazard index l&D Identification and detonation IRP Installation Restoration Program ID Identification Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page v April 2023 lb Pound(s) LUC Land use control LUCIP Land use control implementation plan MC Munitions constituent MDE Maryland Department of the Environment MDNR Maryland Department of Natural Resources MEC HA MEC hazard assessment MEC Munitions and explosives of concern mg/kg Milligram per kilogram MGFD Munition with the greatest fragmentation distance MK2 Mark II mm Millimeter(s) MMRP Military Munitions Response Program MPR Multi-Purpose Range MRS Munitions response site MRSPP Munitions Response Site Prioritization Protocol NAWQC National Ambient Water Quality Criteria NCP National Oil and Hazardous Substances Pollution Contingency Plan O&M Operation and maintenance RAB Restoration Advisory Board RAO Remedial action objective RCRA Resource Conservation and Recovery Act Rl Remedial Investigation ROD Record of Decision RSL Regional screening level SI Site inspection SLERA Screening-level ecological risk assessment SSL Soil screening levels TBC To be considered TMV Toxicity, mobility, and volume TRV Toxicity reference value URS URS Corporation USEPA U.S. Environmental Protection Agency UU/UE Unlimited use and unrestricted exposure UXO Unexploded ordnance WBSA Western Boundary Study Area Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 1 April 2023 1.0 DECLARATION 1.1 Site Name and Location This Record of Decision (ROD) presents the selected remedial actions for three Aberdeen Proving Ground (APG) - Aberdeen Area (AA) munitions response sites (MRSs) located on the northwestern shore of the Chesapeake Bay in southern Harford County and southeastern Baltimore County, Maryland. APG is 3 miles southeast of the City of Aberdeen and approximately 30 miles north of Baltimore (Figure 1). The AA MRSs are listed as Operable Unit 13 under the Michaelsville Landfill National Priorities List Site that includes the APG-AA. 1.2 Statement of Basis and Purpose This ROD presents the selected remedies for the three APG-AA MRSs identified in Table 1. Table 1. List of APG-AA MRSs Addressed in this ROD MRS HQAES Site ID AEDB-R Site ID Selected Remedy Multi-Purpose Range (MPR) 24015.1303 APG-001-R-05 Alternative 2 (Land Use Controls [LUCs]) Former Demolition Area (FDA) 24015.1279 APG-001-R-02 Alternative 2 (LUCs) Gas Identification and Detonation (l&D) Area 24015.1302 APG-001-R-04 No Action NOTES: AEDB-R = Army Environmental Data Base. HQAES = Head Quarters Army Environmental Systems. ID = Identification Number. The locations of the three MRSs are shown on Figure 2. The selected remedies were chosen in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as amended, and to the extent practicable with the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). This decision is based on the Administrative Record file for the APG-AA. This document is issued by the United States Army (Army), the lead agency conducting environmental response activities under the Military Munitions Response Program (MMRP), and the United States Environmental Protection Agency (USEPA), the lead regulatory agency. These actions are being conducted in consultation with the State of Maryland, represented by the Maryland Department of the Environment (MDE), the supporting agency. The MDE concurs with the selected remedies (Appendix A). 1.3 Assessment of Site Based on current conditions at APG-AA, the Army has determined that no unacceptable risks or threats to public health or the environment exist at the Gas l&D Area MRS, which allows for unlimited use and unrestricted exposure (UU/UE). Therefore, no action will be necessary under CERCLA, as amended, to protect public health or welfare and the environment. The remedial actions selected in this ROD for the MPR and FDA MRSs are necessary to protect public health or welfare or the environment from actual or threatened releases of munitions and explosives of concern (MEC) that may present an imminent and substantial endangerment to public health or welfare. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 2 April 2023 1.4 Description of Selected Remedy As noted in Table 1, the selected remedies for the three APG-AA MRSs are: • MPR MRS: Alternative 2: LUCs • FDA MRS: Alternative 2: LUCs • Gas l&D Area MRS: No Action. The MPR and FDA MRSs will remain at their current status, which consists of MEC potentially present at 2 feet below ground surface or greater. No remediation will be performed at the MRSs. Because subsurface MEC may remain, LUCs will be implemented that focus on reducing human exposure to MEC by managing the activities occurring at the MRSs. The LUCs include a Safety Excavation Permit Program with unexploded ordnance (UXO) construction support, training and awareness programs, and annual inspections. Because hazards may remain in the MPR and FDA MRSs that do not allow for UU/UE, CERCLA Five-Year Reviews will be conducted to assess the implementation and performance of the remedy to determine whether the remedy continues to remain protective of human health and the environment. In addition, an MRS Prioritization Protocol (MRSPP) Annual Update will be prepared, in accordance with the requirements of 32 Code of Federal Regulations (CFR) Part 179. The MRSPP is the methodology used by the Department of Defense (DoD) for prioritizing sites known or suspected to contain UXO, discarded military munitions, or munitions constituents (MC) for response actions. The MRS priority ranking is reviewed at least annually, and updated as necessary, to reflect new information. Additional detail on the LUC remedy is provided in Sections 2.9 and 2.12. The Gas l&D Area received a no action recommendation at the conclusion of the remedial investigation (Rl), and this recommendation was maintained through the feasibility study (FS) and Proposed Plan. No action was recommended because the Rl found no evidence of a release, and no unacceptable risks to human health and the environment related to MMRP hazards were present. Therefore, no CERCLA action (i.e., No Action) is necessary to protect human health and/or the environment at the Gas l&D Area MRS. 1.5 Statutory Determinations This section confirms that the selected remedies attain the mandates of CERCLA § 121 and, to the extent practicable, the NCP. Part 1 affirms that the selected remedies satisfy CERCLA § 121 requirements. Part 2 indicates whether the remedies satisfy the statutory preference for treatment as a principal element. Part 3 indicates whether a 5-year review is applicable. No MEC hazards, hazardous substances, pollutants, or contaminants (i.e., MC) were found at the Gas l&D MRS. Therefore, the Army has concluded that no remedial action is necessary to ensure protection of human health and the environment, and a 5-year review requirement is not warranted for the Gas l&D MRS. 1.5.1 Part 1: Statutory Requirements The selected remedy for the MPR and FDA MRSs (LUCs) is protective of human health and the environment, complies with applicable or relevant and appropriate requirements (ARARs), is cost effective, and uses permanent solutions and alternative treatment technologies to the maximum extent practicable. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 3 April 2023 Q O CC 0 Q. < ~' O CC o o o q: 00 Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision Cecil County North-East Harford County Aberdeen-Havre de Grace-Bel Air City of Aberdeen Multi-Purpose Range Gas Identification and Detonation Area Former Demolition Area Spesutie /.lllan*d Lauderick Creek. APG Aberdeen Area Pooles Island Kent County APG Edgewood Area Chester! owfr Anne Arundel County Prince George's County Figure 1 Site Location Aberdeen Proving Ground Maryland Map Projectbn: NAD 1983 StatePlane Maryland FIPS 1900 Feet Base map: ESRI World Street Map WMS I Kilometers I I MRS Location I I APG Aberdeen Area APG Edgewood Area Caroline County Howard County ury county Baltimore ^§ff£ Queen Anne's County Chesapeake Bay I Rising '~~\StLin i Canal Creek ¦ ------- Page 4 April 2023 Figure 2 - Munitions Response Sites, Aberdeen Area, Aberdeen Proving Ground, MD ^ Multi-Purpose Range (APG-001 -R-05) Gas Identification and Detonation Area (APG-001-R-04) Former Demolition Area (APG-001 -R-02) Phillips, AAE ' Airport Legend Monitoring Well A Survey Monument Road Phillips AAF = Stream |_^"j Historic Demo Pit I MRS Areas - - New Buildings t-J (2011) Soil Pile (2011) Pond Golf Fairways Building Wooded Areas Area Shown in Main Map Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 5 April 2023 1.5.2 Part 2: Statutory Preference for Treatment No treatment will be performed. Therefore, the selected remedy for the MPR and FDA MRSs does not satisfy the statutory preference for treatment by reducing the MEC hazard and volume through detection, removal, and permanent destruction of MEC. However, in the unlikely event that MEC are identified during construction support activities conducted under the selected remedy, a minor reduction in toxicity, mobility, and volume through treatment (i.e., detonation) could occur. 1.5.3 Part 3: Five-Year Review Requirement Because hazards may remain in the MPR and FDA MRSs that do not allow for UU/UE, CERCLA Five-Year Reviews will be conducted to assess the implementation and performance of the remedy to determine whether the remedy continues to remain protective of human health and the environment. Therefore, in accordance with NCP § 300.430(f)(4)(H), a statutory review will be conducted within 5 years after initiation of remedial action, and every 5 years thereafter as long as the potential for hazards remains. 1.6 Record of Decision Data Certification Checklist This section provides a data certification checklist (Table 2), which certifies that this ROD contains key remedy selection information. Table 2 includes references to section numbers where the information can be found in the Decision Summary section of this ROD (Section 2.0). Additional information can be found in the APG Administrative Record file maintained at the following locations: Harford County Public Library Edgewood Branch 629 Edgewood Road Edgewood, Maryland 21040 Phone: 410-612-1600 Hours: Mon and Wed: 10 a.m.-8 p.m. Tue and Thu: 1 p.m.-8 p.m. Fri and Sat: 10 a.m.-5 p.m. Sun: Closed Harford County Public Library Aberdeen Branch 21 Franklin Street Aberdeen, Maryland 21001 Phone: 410-273-5610 Hours: Mon and Wed: 10 a.m.-8 p.m. Tue and Thu: 1 p.m.-8 p.m. Fri and Sat: 10 a.m.-5 p.m. Sun: 1 p.m.-5 p.m. Washington College Clifton M. Miller Library Kent County Chestertown, Maryland 21620 Phone: 410-778-7279 Hours: M-F: 8 a.m.-4:30 p.m. APG Administrative Record Building E6882 Aberdeen Proving Ground, Maryland 21010 Phone: 410-436-7313 By appointment only. Table 2. Record of Decision Data Certification Checklist Data ROD Section MEC and their distribution Section 2.5.5 Baseline risks represented by MEC Section 2.7 Cleanup levels for contaminants of concern (COCs) and the basis for these levels Not Applicable How source materials constituting principal threats are addressed Section 2.11 Current and reasonably anticipated future land use assumptions Section 2.6 Potential land and groundwater use that will be available because of the selected remedy Section 2.6 and 2.12.6 Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 6 April 2023 Table 2. Record of Decision Data Certification Record of Decision Data Certification Checklist Data ROD Section Estimated capital costs, annua) operation and maintenance (O&M) costs, total present worth costs, discount rate, and the number of years over which the remedy cost estimates are projected Section 2.12.5 Key factor(s) that led to selecting the remedy Section 2.13 1.7 Authorizing Signatures This ROD presents the selected remedy for three APG-AA MRSs: • MPR MRS: Alternative 2: LUCs • FDA MRS: Alternative 2: LUCs • Gas l&D Area MRS: No Action. The Army is the lead agency under the Defense Environmental Restoration Program and has developed this ROD consistent with CERCLA, as amended, and to the extent practicable with the NGP. Together, the Army and USEPA, the lead regulatory agency, selected the final remedial actions for the MRSs. This ROD will be incorporated into the Administrative Record file for APG, which is available for public review at the locations described in Section 1.6. The undersigned Army and USEPA representatives approve this document, which presents the selected remedy. Date | CAM ARP) Digitally signed by PAUL LEONARD LtUIMnnU Date: 2023.07.26 11:35:52 -04'00' Paul Leonard Director Superfund and Emergency Management Division U.S. Environmental Protection Agency, Region 3 Date Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 7 April 2023 2.0 DECISION SUMMARY This decision summary provides an overview of the characteristics of the munitions response sites (MRSs), the alternatives evaluated, and the analysis of those alternatives. It also identifies the selected remedies, explains how the remedies fulfill statutory and regulatory requirements, and provides a substantive summary of the Administrative Record file that supports the remedy selection decision. Although some of the information in this decision summary is similar to the information in the Declaration (Section 1.0), this section discusses the topics in greater detail and provides the rationale for those "summary declarations." While this document provides a consolidated summary of information about the MRSs and the selected remedies, it is only one part of the Administrative Record file, which contains the full details of the MRSs' characterization, the alternatives evaluation, and remedy selection. This Record of Decision (ROD) has been prepared in accordance with United States Environmental Protection Agency (USEPA) ROD guidance (USEPA 1999, 2011). The ROD is based on the Aberdeen Proving Ground (APG) Aberdeen Area (AA) remedial investigation (Rl) (ERT, Inc. [ERT] 2014), the feasibility study (FS) (Bay West LLC 2017), and the Proposed Plan for the APG-AA MRSs (United States Army [Army] 2022). 2.1 Site Name, Location, and Description The APG installation is located on the northwestern shore of the Chesapeake Bay in southern Harford County and southeastern Baltimore County, Maryland. APG is 3 miles southeast of the City of Aberdeen and approximately 30 miles north of Baltimore (Figure 1). The APG installation encompasses approximately 72,500 acres, which include large bodies of water and marshy, wooded terrain. The Bush River divides the land portion of APG into two separate areas. The area north of the Bush River is referred to as the APG-AA, and the area south of the Bush River is referred to as the APG-Edgewood Area. The APG-AA consists of 27,533 acres of land, and the APG-Edgewood Area consists of 9,734 acres of land. The MRSs addressed in this ROD are in the APG-AA. The MRSs located in APG-Edgewood Area are addressed in a separate ROD. APG is a secure Department of Defense (DoD) facility, and general access is restricted along the property boundary by barriers (i.e., fences), "No Trespassing" signs, and guards. Multiple layers of security exist in some areas and "No Trespassing" signs and random patrols are used in areas where access could be reached by water. However, two of the APG-AA MRSs (the Multi-Purpose Range [MPR] and Former Demolition Area [FDA] MRSs, which together form the Ruggles Golf Course) are outside the restricted-access area. Specific land use controls (LUCs) in place at APG are documented in RODs and are included in APG's Land Use Control Implementation Plan (LUCIP), which is updated periodically. This plan provides an extensive list of practices that are applicable to the entire installation and LUCs implemented by the installation where land could be unsafe for unlimited use and unrestricted exposure (UU/UE). Two examples of these practices are that workers and residents are all trained in the 3Rs (Recognize, Retreat, Report [munitions]) and have been told that digging is prohibited without prior clearance through the safety excavation permit program. This prevents unintentional contact with munitions and explosives of concern (MEC). The process has been demonstrated to be effective as no incidents have occurred since the program was adopted. The FDA and MPR MRSs are south of Route 715; the FDA MRS is the southeastern corner of Ruggles Golf Course and the MPR MRS is the western portion of the golf course (Figure 2). Fill material was placed over the majority of the MRSs when the golf course was initially constructed Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 8 April 2023 in the 1950s. Future land use at the MRSs is expected to remain consistent with current land use, i.e., an active golf course. As noted previously, APG is a secure facility and access is restricted to Army personnel, authorized civilian personnel, contractors, and visitors to specific destinations. However, once on the installation, no barrier is in place surrounding the FDA and MPR MRSs. 2.2 Site History and Enforcement Activities The Defense Environmental Restoration Program (DERP) was formally established by Congress in 1986 and provides for the cleanup of DoD sites under the jurisdiction of the Secretary of Defense. The Army has two restoration programs under DERP at active/operating Army installations: The Installation Restoration Program (IRP) and the Military Munitions Response Program (MMRP). The IRP is a comprehensive program to identify, investigate and clean up hazardous substances, pollutants, and contaminants at active/operating Army installations. The MMRP addresses non-operational range lands that are suspected or known to contain MEC and munitions constituents (MC) located on current and former military installations. The DERP, including the MMRP, follows the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). Management of MEC under DERP-MMRP is being conducted by the Army, the lead agency, in accordance with CERCLA, as amended, and to the extent practicable with the NCP. This action is conducted by the Army with the concurrence of USEPA, the lead regulatory agency. The FDA and MPR MRSs are associated with the APG Michaelsville Landfill National Priorities List Site (MD3210021355), which was placed on the National Priorities List in October 1989. A series of assessments, site inspections (Sis), RIs, an FS, and other data collection activities under CERCLA and DERP have occurred at the APG-AA MRSs addressed in this ROD since 2006. A summary of the investigations and actions performed at APG-AA addressing potential MEC and MC are summarized in Table 3. A description and history of the three MRSs are presented in Section 2.5. Table 3. MMRP Activity Timeline Date Activity 2006 Historical Records Review—Potential MRSs identified at APG-AA through interviews and archive research. The three MRSs in this ROD were not identified through the Historical Records Review. 2007 SI—Environmental sampling and field surveys were performed. The three MRSs in this ROD were not investigated during the SI. 2008 Contractor finds MEC and munitions debris near Ruggles Golf Course. 2008 Preliminary Assessment for FDA—Research into the historical activities that led to the MEC being present near the Golf Course was performed. As part of the Preliminary Assessment for the FDA, an additional search and review of historical records detailing potential use of the site was conducted and three additional MRSs were identified: Combat Course, Gas Identification and Detonation (l&D) Area, and MPR. 2010 SI Addendum—No fieldwork performed. Report updated the previous SI Report to include the three MRSs included in this ROD. 2011 Western Boundary Area Rl—Groundwater in Operable Unit 2, which includes the three MRSs in this ROD, was investigated. Groundwater sampling confirmed that no impacts to groundwater from activities at the MRSs had occurred. 2014 APG-AA Rl—Included digital geophysical mapping (DGM), environmental sampling for MC, intrusive MEC investigations, and human health and ecological risk evaluations. 2017 FS to evaluate remedial alternatives for the MPR and FDA MRSs. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 9 April 2023 Table 3. MMRP Activity Timeline Date Activity 2022 Proposed Plan to present the preferred alternatives for the MPR, FDA, and Gas l&D Area MRSs. 2.3 Community Participation The NCP § 300.430(f)(3) establishes several public participation activities that the lead agency must conduct during the remedy selection process. Components of these activities and documentation of how each component was satisfied for the MRSs are described in Table 4 and Table 5. Table 4. Public Notifical tion of Document Availability Requirement Satisfied By Notice of the availability of the Proposed Plan must be made in a general-circulation major local newspaper. Notice of availability was published on 18 March 2022 in The Aegis, The Cecil Whig, and the Kent County News, and is included for reference in Appendix B. Notice of the availability must include a brief abstract of the Proposed Plan, which describes the alternatives evaluated and identifies the preferred alternative [NCP § 300.430(f)(3)(i)(A)]. The notice of availability included the required components and is included for reference in Appendix B. Table 5. Public Comment Period Requirements Requirement Satisfied By The lead agency should make the document available to the public for review on the same date as the newspaper notification. The Proposed Plan was made available to the public on 18 March 2022. The lead agency must ensure that all information that forms the basis for selecting the response action is included as part of the Administrative Record file and is made available to the public during the public comment period. The APG Directorate of Public Works— Environmental Division maintains the Administrative Record file for the MRSs and included a copy of relevant documents in an Information Repository at the Harford County Library (Edgewood and Aberdeen Branches). Data collected and CERCLA primary documents produced for the MRSs were placed therein and made available to the public at those locations. CERCLA § 117(a)(2) requires the lead agency to provide the public with a reasonable opportunity to submit written and oral comments on the Proposed Plan. NCP § 300.430(f)(3)(i)(C) requires the lead agency to allow the public a minimum of 30 days to comment on the Proposed Plan and other supporting information located in the Administrative Record. The Army provided a public comment period for the Proposed Plan and other supporting information from 21 March 2022 to 20 April 2022. The lead agency must extend the public comment period by at least 30 additional days upon timely request. The Army received no requests to extend the public comment period. The lead agency must provide the opportunity for a public meeting to be held at or near the MRS during the public comment period. A virtual public meeting was held on 31 March 2022. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 10 April 2023 2.4 Scope and Role of Munitions Response Site Response Action There are two APG areas under investigation, the APG-AA and APG-Edgewood Area. Each of these areas have multiple IRP sites and MMRP sites that are in various stages of investigation and remediation. This ROD addresses three of the four MMRP sites within APG-AA (MPR MRS, FDA MRS, and Gas l&D Area MRS). The fourth site (Enhanced Use Lease [EUL] Site MRS) is being addressed in a separate ROD. Activities at the MRSs have been and are currently being performed in accordance with the CERCLA remedial process and are consistent with the NCP. The remedial actions selected in this ROD are the final remedies for the MRSs addressed. 2.5 Site Characteristics This section provides an overview of the site, including a description of the conceptual site model (CSM) on which the risk assessment and response actions are based. The CSM is a description of a site and its environment that is based on existing knowledge. The CSM describes the sources of MEC and MC hazards at a site, actual or potential pathways of exposure, current or proposed use of property, and potential receptors to MC or explosives hazards. The CSM provides a planning tool to integrate site information from a variety of sources, evaluate the information with respect to project objectives and data needs, and respond through an iterative process for further data collection or response action. Development of the CSM is a process that reflects the progress of activities at the MRSs from initial assessment through site closeout. Information used to create the CSM includes the following: • Facility Profile: Describes history, location, and man-made features at or near the site • Physical Profile: Describes factors that may affect release, fate, and transport • Land Use and Exposure Profile: Provides information used to identify and evaluate the applicable exposure scenarios and receptor locations • Ecological Profile: Describes the physical relationship between developed and undeveloped portions of the site, use of the undeveloped portions, and ecological use • Nature and Extent of MEC/Release Profile: Presents the extent of contaminants or hazards in the environment. These profiles are described in detail in the following subsections (land use is described in Section 2.6). A visual depiction of the current site MEC CSM is presented in Figure 3. 2.5.1 Facility Profile MPR MRS: The 179.8-acre MPR MRS is adjacent to the FDA MRS and lies south of Route 715 and east of the installation boundary in the APG-AA. The western portion of Ruggles Golf Course currently overlies the former location of the MPR MRS. Aerial photographs indicate that the MPR MRS was constructed between 1945 and 1947 and use of the range ended between 1952 and 1956. Historical data indicate the site was used for training with mines and booby traps, rifle grenades, hand grenades, and rocket launchers (ERT 2014). The MPR MRS was initially identified as an MRS in 2008 during review of a 1951 Ordnance Replacement Training Center Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 11 April 2023 map completed as part of the preliminary assessment (APG 2008). Fill material was placed over the majority of the MPR MRS when the golf course was initially constructed in the 1950s. FDA MRS: The 59.4-acre FDA MRS is located south of Route 715 on the eastern portion of Ruggles Golf Course. The FDA MRS was used by the Ordnance Replacement Training Center from 1942 through 1947 (URS Corporation [URS] 2007). Historical documentation indicated that there was also a 23-acre Bomb Recovery Area within the FDA that was used by the Ordnance Center and School in the mid-1950s for recovering inert bombs dropped from aircraft. During this training, an inert bomb was dropped by aircraft and would penetrate the ground surface. Trainees would be required to locate the point of entry, access the bomb, and then render safe and recover the bomb (EA Engineering, Science, and Technology, Inc. [EA] 2011). Munitions discovered at the MRS include high explosive (HE) loaded projectiles, grenades, fuzes, bombs, boosters, and rockets. These included munitions of both American and foreign origins. The FDA was initially identified as an MRS in January 2008 when civilian unexploded ordnance (UXO) contractors encountered 57 MEC/munitions debris items at 5-6 feet (ft) below ground surface (bgs) during excavation of an irrigation pond on Ruggles Golf Course (ERT 2014). The irrigation pond is within the boundaries of the historical demolition pit. These items were recovered and properly disposed of and/or detonated in place by Explosive Ordnance Disposal (EOD) personnel, and the remaining metal was recycled offsite. The items included the following: two point-detonating fuzes, one booster, one HE hand grenade, one 20-millimeter (mm) armor-piercing (AP) projectile, one 20-mm HE projectile, one German 20-mm HE projectile, three German 37-mm AP HE projectiles, two 40-mm Mark II (MK2) HE incendiary with tracer (HEI-T) projectiles, 26 40-mm projectiles (not intact), one 57-mm HE projectile, one 57-mm M306 projectile, nine 75-mm HE projectiles, two experimental 75-mm AP projectiles, one 76-mm HE projectile, three 90-mm projectiles, one 105-mm M1 HE projectile, and one 3.5-inch rocket warhead. The 3.5-inch rocket warhead was confirmed to be MEC. Per an APG summary report to Maryland Department of the Environment (MDE), buried ordnance was also discovered near the demolition pit within the FDA MRS during April 2010 construction excavation activities at the golf course. These munitions were subsequently recovered and properly disposed of and/or detonated in place by EOD personnel. The items included: one 500-pound (lb) bomb (unfuzed); one 155-mm projectile with armed fuze; six 37-mm projectiles; three fuzes; and two 100-lb bombs. Because of these discoveries, APG EOD personnel conducted mandatory pre-construction UXO sweeps of all planned excavation areas during golf course construction upgrades. Fill material was placed over most of the FDA MRS when the golf course was initially constructed in the 1950s. The fill material was observed during construction of the irrigation pond within the FDA MRS in 2008. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 12 April 2023 Figures. MEC Conceptual Site Model Source Interaction Primary Source Acess Location Release Mechanism Exposure Routes Receptors CURRENT/FUTURE Authorized Installation Personnel Authorized Contractors Trespassers Ecological Receptors MEC MEC at the Surface ? Handle/Tread Underfoot Access Available Frost Heave/Flood/Erosion ? No Access MEC near surface the Subsurface Intrusive activity 0.1 -2ft MEC in the Subsurface Intrusive activity © © >2ft The MRSs have been covered with fill material and investigation data indicate that the exposure pathway for interaction between humans and MEC on the surface and near surface (less than 2 ft bgs) is incomplete. Complete Pathway © Potentially Complete Incomplete Pathway Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 13 April 2023 Gas l&D Area MRS: The 4.4-acre Gas l&D Area MRS is approximately one-half mile east of the other two MRSs, just south of Route 715. The Gas l&D MRS was identified on a 1951 map that detailed training areas used by the Ordnance Replacement Training Center. A gas training chamber was also identified, but it is not eligible for the MMRP because it is in a closed structure. The MRS included a 100-yard by 170-yard area that was used to train soldiers to be proficient in the identification of gases through odor and other sensory reactions. Although the specific period of operation of the range is unknown, operations could have been conducted from the World War II period through at least the Korean War. During the time frame in which the area may have been used for training (approximately the 1940s through the mid-1950s), the following Chemical Agent Identification Sets (CAIS) may have been used at APG: M1 (K951 and K952) and AN-M1A1 (K953 and K954). CAIS kits are not considered MEC items; therefore, there is no potential for explosive hazards at the MRS. The CAIS consisted of agents and industrial chemicals in sealed Pyrex® containers. Typical procedures started by burying canisters in shallow holes, approximately 10-20 yards apart. Detonators were fastened to each tube with adhesive plaster. Tubes were laid in the holes with detonators underneath so that the explosion would throw the liquid into the air and produce a cloud of vapor. The M1 CAIS and the AN-M1A1 CAIS contained various chemical agents in small dilute quantities, including chloropicrin, phosgene, sulfur or nitrogen mustard, lewisite, cyanogen chloride, and tabun. Safety procedures in place directed that the detonators be kept separate from the CAIS and not be left at the site, so it is unlikely that any detonators would be present. During the Rl, the majority of the Gas l&D MRS was being used to stockpile soil associated with Base Realignment and Closure (BRAC) construction efforts at APG (ERT 2014). Therefore, the depth of subsurface soil samples was adjusted to collect samples beneath the stockpile soil to evaluate the nature and extent of potential historical impacts to human health and the environment. 2.5.2 Physical Profile 2.5.2.1 Meteorology APG experiences a modified temperate climate. The atmospheric effects caused by the installation's proximity to the Chesapeake Bay, the Atlantic Ocean, and Appalachian Mountains prevent APG from having a typical mid-latitude temperate climate. Wnters are humid and generally milder than in the inland areas, and summers are hot and humid with frequent thunderstorms. The average annual air temperature is approximately 55 degrees Fahrenheit (°F). Average daily temperatures generally range from 33°F in the winter to 75°F in the summer. Temperatures commonly exceed 90°F during the summer and are accompanied by high humidity, yielding a subtropical climate. The average relative humidity is 74 percent (%). The warmest period of the year is during July and August, and the coldest period of the year is during January and February. Average annual precipitation is approximately 42 inches. The distribution of monthly precipitation is uniform throughout the year; the maximum precipitation usually occurs in late spring, or mid- to late summer, and the minimum precipitation usually occurs in late summer or fall (National Oceanic and Atmospheric Administration 2012). The depth of the frost line for the area is 64 inches, per Unified Facilities Criteria 3-310-01, dated 25 May 2005. This depth is considered to be the depth at which a significant number of frost cycles are expected, there is frost susceptibility, and moisture is available. All three of these parameters are required to produce frost-related migration of MEC. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 14 April 2023 Prevailing winds are from the west to northwest in the fall and winter and from the south to southwest in the spring and summer. Average annual wind velocity ranges from 6 to 10 miles per hour but can reach over 50 miles per hour and higher during severe storms (URS 2007). 2.5.2.2 Surface Features APG is located within the Atlantic Coastal Plain, which is characterized by low-lying wetlands, gently rising knolls and hills, with little change in elevation. These features were created as material eroded from the hills to the west and was deposited eastward. APG topography and surface features are characterized by low hills, shallow valleys, flat plains and extensive marshes. Elevations range from 0 to 70 ft above sea level. Small creeks drain the land surface and discharge into the Chesapeake Bay or tributaries of the bay. The shoreline is typical of the bay's western shore (low, marshy shorelines to steep bluffs 15-20 ft in height). 2.5.2.3 Soil The soil at APG is moderately to well drained, and is underlain by sandy, loamy, gravelly, or clayey sediments on smooth uplands. Soil of the floodplains and low terraces is generally moderately well drained to well drained and is underlain by stratified alluvial sediments. The dominant soil types present are the Sassafras, Elkton, and Keyport series. All three series developed from the deposition of marine sediment. Along most non-tidal wetland areas, the Meadow series/Alluvial land series is dominant. In tidally influenced wetlands, the Tidal Marsh series is dominant. Surface soil and sediment near marshes, low-lying floodplain areas, and the shorelines contain abundant organics. Many of these soils include peat, organic-silt, and organic clay with varying sand content. At the FDA and MPR MRSs, as at most areas of APG, fill from other locations has been added as improvements or soil has been reworked over the past 50 years. 2.5.2.4 Surface Water All surface water systems within APG are linked to the Chesapeake Bay, its tributaries, and associated wetlands. The APG-AA lies within the Gunpowder-Middle-Back-Patapsco-Magothy- Severn-South-Rhode-West drainage system. Over 39,000 acres of APG consist of the waters of the Chesapeake Bay and its tributaries. The developed eastern section of APG-AA is drained primarily by the upper portions of Romney Creek, and by Swan, Woodrest, and Dipper Creeks, which flow into Spesutie Narrows. Undeveloped portions of APG-AA are drained by the lower branches of Romney, Mosquito, and Delph creeks, and the Bush River. The Susquehanna River joins the Chesapeake Bay approximately 4 miles north of Spesutie Island. In this region of the Upper Bay, the Susquehanna accounts for 97% of the incoming freshwater and most of the fluvial sediments that enter the Chesapeake Bay. Due to the massive influx of freshwater from the Susquehanna watershed, seasonal and annual fluctuations in salinity, turbidity, and water chemical quality are common. The location of APG in this portion of the bay, where a delicate mixture of salt and fresh water occurs, makes the installation's waters an important environment for the reproduction and rearing of many estuarine and marine organisms (ERT 2014). Modified wetlands and drainages are common throughout the installation. Small ponds created by military activities and wildlife are regular features in the landscape of the unmanaged portions of APG. Man-made drainage channels that vary from 0.5 to 7.0 ft in width and from 1.0 to 6.0 ft in depth are frequent in low-lying portions of the installation. These drainage structures are Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 15 April 2023 associated with underground pipe systems and open ditches that are constructed from a variety of materials (ERT 2014). Decorative man-made drainage ponds are present at the golf course. In the MPR MRS, near the approximate geographic center of the golf course, a small pond is present. This pond and a larger pond, north of Route 715, discharge south via a drainage ditch or intermittent stream. In the FDA MRS, another small man-made irrigation pond is present in the eastern portion of the MRS, within the historical demolition pit area. Although these three water bodies may be used by wildlife such as amphibians, fish, and birds, an initial site walkover and observations made during the Rl fieldwork indicated low ecological use of the ponds (ERT 2014). The MPR and FDA surface water features are not used for drinking water or fishing. 2.5.2.5 Hydrogeology Shallow (10-37 ft bgs) groundwater is present at the APG-AA MRSs. A groundwater divide exists in the shallow groundwater aquifer, such that groundwater north of the golf course discharges to Swan Creek. However, from the MPR and FDA MRSs, the shallow groundwater flows west- southwest. The shallow groundwater at the Gas l&D MRS flows north-northeast. Groundwater at the Gas l&D MRS was not sampled during the investigation because there was no historical MEC usage at this MRS. Although a clay layer separates the upper and lower aquifers (30-80 ft bgs) beneath the MPR MRS and FDA MRS, it may only be a semi-confining layer as it appears that the aquifers become interconnected west and south-west of the MRSs. Historical water table measurements were used to contour and compare to the estimated elevations of the surface water bodies on the golf course (a south-flowing intermittent stream in the center of the MPR MRS, a small pond just west of the stream in the center of the MPR MRS [central pond], and an irrigation pond in the FDA MRS demolition pit area) to determine if groundwater could mix with surface water. Under most conditions, groundwater is unlikely to be affecting the surface water. For the irrigation pond in the FDA MRS, the bottom of the pond is estimated to be 20 ft above the water table, indicating that there is no hydraulic connection between surface water and groundwater. For the stream bed and the central pond, however, the water table is only a few feet below the bottom of the stream bed and central pond. Although the likelihood is small, it is possible that a hydraulic connection may occur during extreme storm events. 2.5.3 Land Use Profile 2.5.3.1 Demography The population of Harford and Baltimore Counties as reported in the 2021 U.S. Census was 1,112,293. The MRS is located approximately 3 miles southeast of the City of Aberdeen, which had a population of 16,889 in 2021. Current and potential future land and water use is described in Section 2.6. 2.5.4 Ecological Profile The MPR and FDA MRSs are a part of a developed golf course where fill has been added over many years. Although the area is accessible to wildlife, the conditions are not ideal for these receptors, as the area is regularly mowed and visited by golfers. The highly developed conditions at the MRSs may represent a low-value habitat for birds and terrestrial mammals, as the degree Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 16 April 2023 of disturbance is high. Many acres of secondary forest growth and wetlands exist elsewhere on the installation, mainly located on the active range areas. The physical boundaries of the Western Boundary Study Area (WBSA) Rl included the Ruggles Golf Course and former Gas l&D area. The ecological setting of the WBSA consists of a mixture of mowed/unmowed open fields, developed areas, marsh areas, and forests; the Ruggles Golf Course area consists primarily of a large, mowed, grassy area surrounded by narrow stands of trees, and containing a few buildings, small ponds, and a stream/drainage ditch that contains running water only after storm events (EA 2011). Common terrestrial wildlife species that would be expected to use the MRSs include white-tailed deer (Odocoileus virginianus), gray squirrel (Sciurus carolinensis), eastern chipmunk (Tamias striatus), red fox (Vulpes vulpes), groundhog (Marmota monax), and opossum (Didelphis virginiana). Species that exist in marshes in the area and that might be locally present in the man- made lakes on Ruggles Golf Course include muskrat (Ondatra zibethicus), herons, egrets, rails, and various turtles and amphibians. The WBSA Rl report (EA 2011) lists vegetation in the marshes of the WBSA, and it is assumed that similar vegetation can be found in the ponds and intermittent streams of the golf course. Common plant species associated with the WBSA waters include grasses, sedges, cattail (Typha spp.), arrow-arum (Peltandra virginica), pickerel weed (Pontenderia cordata), common winterberry (Ilex verticillata), marsh mallow (Kosteletzkya virginica), and common reed (.Phragmites australis). Although no specific data were found regarding the aquatic invertebrates of the freshwater ponds and streams of APG, freshwater invertebrates in Maryland streams are outlined in a document by the Maryland Department of Natural Resources (MDNR 2002). It is assumed that, in general, typical species of freshwater invertebrates exist in the golf course ponds and intermittent streams, and may include mussels and clams (Bivalvia), snails and limpets (Gastropoda), insect and non-insect Arthropoda, Collembola, and aquatic worms. 2.5.5 Nature and Extent of MEC/MC Release Profile The nature and extent of contamination includes the sources and types of MEC and MC, their inferred mechanisms for release, and any potential influences from natural features or events that could affect distribution. The profile builds upon the historical, physical, and ecological information presented in the preceding sections. In the various environmental investigations that have been completed for the APG-AA MRSs, soil analytical results were compared to APG and regional background levels, USEPA residential soil Regional Screening Levels (RSLs), MDE Residential Soil Cleanup Standards, USEPA Protection of Groundwater Soil Screening Levels (SSLs), and USEPA Ecological SSLs. Groundwater analytical results were compared to MDE Groundwater Cleanup Standards for future residential use of groundwater and to USEPA tapwater RSLs. Sediment results were compared to USEPA Region III Freshwater Sediment Screening Benchmarks and sediment background levels. Surface water analytical results were compared to surface water background levels, USEPA National Ambient Water Quality Criteria (NAWQC) for protection of aquatic life, and MDE Ecological Screening Criteria. MC investigation results are briefly described below. A summary of the risk evaluation is presented in Section 2.7. 2.5.5.1 MPRMRS Nature and Extent of MEC: DGM survey methods were used to identify anomalies and intrusive procedures were used to investigate anomalies during the Rl. A total of 41 grids covering Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 17 April 2023 8.7 acres were delineated. One hundred percent of electromagnetic targets within grids were intrusively investigated. No MEC were found, indicating that there is a low probability of encountering MEC within the MPR MRS. Per the DoD Explosive Safety Manual 6055.09-M, a "low probability for encountering MEC determination" can be made if a search of available historical records and onsite investigation data indicates that, given the military or munitions-related activities that occurred at the site, the likelihood of encountering MEC is low. Per the DoD guidance and results of the Rl, the probability of encountering MEC in the MPR MRS is, therefore, deemed to be "low." Based on the findings from the Rl and the fact that the Ruggles Golf Course (excluding the greens and tee boxes) was previously cleared by APG EOD personnel, the potential for MEC to remain at the MPR MRS is very low. Nature and Extent of MC: Environmental sampling of soil, surface water, sediment, and groundwater for MC was also completed during the Rl. The results from both MPR and FDA MRSs were combined as the MRSs are both located in Ruggles Golf Course. MC investigation results for each media are briefly described below. MC in Soil—Surface soil was not considered representative of past military munitions activities at the MRSs due to the presence of fill material at the golf course. Surface soil samples (0-1 ft bgs) were not collected to characterize MC; subsurface soil samples (2-6 ft bgs) were collected at depths that represented the native soil/fill material interface where evidence of past MRS operations may be encountered. Subsurface soil samples were analyzed for MC (metals and explosives), and perchlorate. Surface soil samples were also collected from the golf course and analyzed for perchlorate to assess possible perchlorate contributions from golf course fertilizers. No explosives compounds above the detection limits were found in any samples collected at the MPR or FDA MRSs. Perchlorate was detected in only one subsurface soil sample at the FDA MRS, and the concentration was below the residential human health RSL. Arsenic and manganese were detected in subsurface soil above human health screening criteria but were within background ranges. Antimony, chromium, lead, manganese, and mercury were detected in subsurface soil above ecological SSLs but, as described in Section 2.7, they are not likely to present an unacceptable ecological risk. MC in Sediment—Sediment samples were collected from a man-made pond at the FDA MRS and one man-made pond and its outflow (an intermittent stream) at the MPR MRS. Samples were analyzed for metals, explosives, and perchlorate. Explosives and perchlorate were not detected. All metals were within background ranges in sediment. MC in Groundwater— Groundwater was collected from five existing monitoring wells located both within and outside of the MRSs. Samples were analyzed for metals, explosives, and perchlorate. Explosives were not detected. Perchlorate was detected in all five samples below the MDE residential cleanup standard for groundwater. Aluminum, iron, manganese, and zinc concentrations were found at levels higher than the human health-based MDE Groundwater Cleanup Standard but were within background ranges. Aluminum, copper, iron, lead, manganese, nickel, and zinc were detected in groundwater at concentrations higher than ecological surface water screening values, but as described in Section 2.7, they are not likely to present an unacceptable ecological risk. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 18 April 2023 MC in Surface Water and Groundwater (via potential interaction with Surface Water)—Surface water samples were collected from a man-made pond at the FDA MRS and one man-made pond and its outflow (an intermittent stream) at the MPR MRS. Samples were analyzed for metals, explosives, and perchlorate. Explosives and perchlorate were not detected. Arsenic was above human health screening levels in surface water. Aluminum, arsenic, copper, iron, lead manganese, and mercury concentrations were above ecological screening levels in surface water, but as described in Section 2.7, they are not likely to present an unacceptable ecological risk. 2.5.5.2 FDA MRS Nature and Extent of MEC: DGM survey methods were used to identify anomalies and intrusive procedures were used to investigate anomalies during the Rl. The geophysical investigation of the FDA MRS was performed in the former demolition pit and in the area outside of the pit. A different approach for each area was used. Within the demolition pit, DGM covered 100% of the 5.3-acre area. A total of 450 of the 1,800 geophysical anomalies mapped were intrusively investigated. A single MEC item was found (81mm illumination mortar). The MEC item was recovered in the "fill" material that came from other locations on APG. There is no historical evidence of these types of MEC being fired in this area; therefore, it is unlikely that additional mortars are present. However, the typical detection depth is roughly 12 times the diameter of the item so location of small items below the fill may have been beyond the limitations of the technology. The statistical analysis of the demolition pit area performed for the Rl indicated that there are fewer than 3.019 MEC/acre with 95.06% confidence; therefore, there is a low probability of encountering MEC within the demolition pit area of the FDA MRS. In the area outside of the former demolition pit area, data were collected along randomly placed transects; all geophysical targets on these transects were intrusively investigated, and no MEC were found. This indicates that there is a low probability of encountering MEC within the FDA MRS outside of the demolition pit area. Based on the findings of the Rl and the fact that Ruggles Golf Course (excluding the greens and tee boxes) was previously cleared by APG EOD personnel, the potential for MEC to remain at the FDA MRS is very low. Nature and Extent of MC: As noted under the MPR MRS, the MC investigation results for both MRSs were combined because the MRSs are both located in Ruggles Golf Course. See the MPR MRS Nature and Extent of MC discussion for details. 2.5.5.3 Gas i&D Area MRS Nature and Extent of MEC: There is no potential for MEC in the Gas l&D Area MRS; therefore, a MEC investigation was not performed. Nature and Extent of MC: Soil samples were collected to evaluate whether the historical activities had impacted the environment. Soil samples were collected for arsenic and mustard breakdown products. No mustard breakdown products were detected. Arsenic was detected at levels above human health screening criteria but within background ranges. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 19 April 2023 2.5.5.4 Munitions and Explosives of Concern Release Mechanisms Mechanisms for MEC release at the FDA MRS include the use of the area for training including deliberate or unintentional detonation of munitions. Munitions discovered at the MRS include HE loaded projectiles, grenades, fuzes, bombs, boosters, and rockets. Mechanisms for MEC release at the MPR MRS include the use of the area for firing and training with mines and booby traps, rifle grenades, hand grenades, and rocket launchers. The locations for potential MEC releases were established during the SI (Malcom Pirnie 2010) and Rl (ERT 2014). The open detonation for demilitarization or destruction of ordnance could also contribute to the release of MEC. Fill material was placed over most of the FDA and MPR MRSs when the golf course was initially constructed in the 1950s. 2.5.5.5 Interaction with MEC and MC There are no unacceptable MEC or MC risks to human health and the environment at the Gas l&D Area MRS; therefore, there is no potential for interaction with MEC and MC at the Gas l&D Area MRS. In addition, there are no unacceptable MC risks to human health and the environment at the MPR and FDA MRSs. Therefore, there is no potential for interaction with MC at the MPR and FDA MRSs. The potential for interaction between humans and MEC on the surface and near surface (less than 2 ft bgs) at the MPR and FDA MRSs is considered incomplete. There is a potential for interaction between authorized base personal/contractors performing intrusive activities and MEC in the subsurface at the MPR and FDA MRSs. However, human interaction with subsurface MEC is considered low/potentially complete. The potential for interaction of ecological receptors with MEC on the ground surface is incomplete. The potential for interaction of ecological receptors with MEC in the subsurface (greater than 2 ft bgs), is anticipated to be potentially complete in the FDA and MPR MRSs. Terrestrial habitats at the MRSs support a limited range of animals, some of which include burrowing activity in their behavior. Subsurface disturbances can lead to transport and migration of MEC from one environmental medium to another. Natural physical influences typically include erosion, precipitation runoff, and frost heave. Chemical interactions with media or water influx may cause corrosion or leaching of MEC and may vary with proximity to the surface and surrounding geochemistry of media. 2.6 Current and Potential Future Land Use and Resource Uses 2.6.1 Land Use The current and reasonably anticipated future land uses were used to evaluate risk (Section 2.7) and form the basis for reasonable exposure assessment assumptions and risk characterization conclusions. According to the APG Land Use Assessment, current land use at APG includes operational range, research and development, supply/storage, open space, outdoor recreation, administration, airfield, and industrial uses. Buildings are used for warehousing, offices, and research and development activities. The current land use of the MPR and FDA MRSs is a golf course (i.e., Ruggles Golf Course). The future land use is expected to remain consistent with current land use as Ruggles Golf Course. Surrounding land use includes residential housing, commercial, and industrial areas. Access to these MRSs is unrestricted. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 20 April 2023 During the Rl, the majority of the Gas l&D MRS was being used to stockpile soil associated with BRAC construction efforts at APG (ERT 2014). The future use of the Gas l&D Area MRS is anticipated to be the same as the current land use. Access to this MRS is unrestricted. 2.6.2 Groundwater and Surface Water Uses Harford County production wells, a drinking water source, are in a deep groundwater aquifer more than 2,000 ft downgradient (west-southwest) of the MPR and FDA MRSs. Some of these wells have documented solvent contamination from a chlorinated solvent plume that is not associated with the MRSs. Although a clay layer separates the upper and lower aquifers beneath the MPR MRS and FDA MRS, it may only be a semi-confining layer as it appears that the aquifers become interconnected closer to the Harford County production wells. The City of Aberdeen has a well field of 11 wells located in the northwestern portion of APG, just north of the Ruggles Golf Course. All these city wells are currently in use. These wells are hydrogeologically upgradient of the FDA MRS and MPR MRSs and are pumped from a deep (lower) aquifer (casing depths ranging from 30 to 80 ft bgs) within the Talbot Formation, located beneath a confined or semi-confined clay layer. The shallow groundwater at the Gas l&D MRS flows north-northeast; there are no public water supply wells in this direction. Sites in APG-AA and all of APG-Edgewood Area may have groundwater contamination above maximum contaminant levels established under the Safe Drinking Water Act. Consequently, the Harford County Health Department and MDE require that potable groundwater wells be permitted with the Health Department before installation. Although groundwater from the upper aquifer is not currently withdrawn for residential use at the APG-AA MRSs, groundwater was identified as a potentially complete future exposure pathway due to the existence of public water supply wells in the area. All surface water systems within APG are linked to the Chesapeake Bay, its tributaries, and associated wetlands. Modified wetlands and drainages are common throughout the installation. Small ponds created by military activities and wildlife are a regular feature in the landscape of the unmanaged portions of APG. Decorative man-made drainage and irrigation ponds are present at the golf course. Although these water bodies may be used by wildlife such as amphibians, fish, and birds, an initial site walkover and observations made during the Rl fieldwork indicated low ecological use of the ponds (ERT 2014). 2.7 Summary of Site Risks As part of the MMRP Rl, the Army conducted a baseline risk assessment to determine the human health and ecological risks associated with MC and MEC at the three MRSs. In summary, there are no unacceptable MC risks to human health and the environment at the MRSs. In addition, there are no unacceptable MEC risks to human health and the environment at the Gas l&D Area MRS. A summary of the MC and MEC risk assessment results is included in the following subsections. 2.7.1 MC Risk Assessment The baseline risk assessment estimates what MC risks the site would pose if no action were taken. It provides the basis for taking action and identifies the contaminants and exposure pathways that need to be addressed by the remedial action. This section of the ROD summarizes the results of the baseline risk assessment for the site. Soil analytical results were compared to APG and regional background levels, USEPA residential soil RSLs, MDE Residential Soil Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 21 April 2023 Cleanup Standards, USEPA Protection of Groundwater SSLs, and USEPA Ecological SSLs. Groundwater analytical results were compared to MDE Groundwater Cleanup Standards for future residential use of groundwater. Sediment results were compared to USEPA Region III Freshwater Sediment Screening Benchmarks and sediment background levels. Surface water analytical results were compared to surface water background levels, USEPA NAWQC for protection of aquatic life, and MDE Ecological Screening Criteria. Human Health Risks: Data that form the basis for the human health risk assessment (HHRA) were collected during the Rl. The HHRA risk characterization estimated the potential excess lifetime cancer risk and potential for non-cancer adverse health effects for human receptors exposed to contaminants of potential concern (COPCs) in soil, surface water, sediment, and/or groundwater at the three MRSs. Receptors evaluated in the HHRA included installation personnel, contractors, trespassers, visitors (golfers), and future residents (for groundwater only). The HHRA concluded that no human health risks are likely to be associated with potential human contact with COPCs detected in subsurface soil, surface water, or sediments at the three MRSs. A brief discussion of the media and COPCs follows. Subsurface Soil—Arsenic was identified as a human health COPC in subsurface soil at all three MRSs. The maximum soil concentration for arsenic (9.94 milligrams per kilogram [mg/kg]; FDA- SO-03-03) was found in the FDA MRS. The HHRA indicated that the maximum arsenic concentrations on the MRSs were greater than MDE residential and non-residential cleanup standards and the USEPA residential and industrial soil RSLs. However, the HHRA noted that the MDE recommended soil arsenic level for recreational purposes is 10 mg/kg (MDE 2010 cited in ERT 2014). Because the concentrations of arsenic at the MRSs were below the recommended recreational soil value, the HHRA determined that further quantitative risk assessment for arsenic in soil for the three MRSs was not warranted. Manganese was identified as a human health COPC in subsurface soil at the MPR MRS and FDA MRS. The maximum soil concentration of manganese (1,060 mg/kg; MPR-SO-15-04) was found in the MPR MRS. The maximum detected concentration was greater than the MDE residential soil cleanup standard but less than the MDE non-residential soil cleanup standard and less than the USEPA residential soil RSL. As documented in the Rl Report, manganese background 95% UPL =1,517 mg/kg, while detected subsurface soil manganese is lower with a maximum detected concentration = 1,060 mg/kg. The USEPA residential soil RSL for manganese in the Rl was based upon a HQ of 1, while all other metals were based upon an HQ of 0.1. The MDE residential soil screening value was based upon a HQ of 0.1. Additionally, detected subsurface soil concentrations were statistically less than site-specific background. Therefore, further quantitative assessment of manganese in soil was not warranted for the HHRA. Surface Water—Although surface water (two ponds and one intermittent stream) at the FDA and MPR MRSs is not used for drinking water or for fishing, arsenic was identified as a human health COPC in surface water because it was present at a concentration greater than the USEPA NAWQC. The NAWQC are conservative levels that are used for screening purposes to ensure the safety of individuals drinking the water and ingesting fish caught in the water. The single detection of arsenic in surface water (5.96 micrograms per liter [|jg/L]; FDA-SW-01) was greater than the four detects in background surface water (range of 2.1-3.1 |jg/L, and 95% upper prediction limit of 1.86 |jg/L, including consideration of non-detects). However, the onsite surface water concentration of arsenic is not expected to cause adverse human health impacts because the actual human contact with surface water most likely to occur at the MRSs (e.g., accidental dermal contact) results in less exposure than would occur via ingestion of water and fish, which are not expected to happen at the golf course water bodies. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 22 April 2023 Groundwater— Manganese and zinc were identified as human health COPCs in groundwater at the FDA and MPR MRSs because their maximum concentrations were greater than the MDE Cleanup Standards for Groundwater. Aluminum and iron were also detected above the MDE Cleanup Standards for Groundwater. A comparison to the tap water RSL reveals that only one detection of iron within well AARI-MPR-GW-FTA-PZ-02, which had the maximum detected concentration for all metals. The Rl report noted this sample, "Observations in the field of high turbidity in this sample indicate that this sample contained suspended particulates (ERT 2014)" which likely contributed to the tap water RSL and MDE cleanup standards for groundwater. Therefore, iron and manganese were not selected as COPCs. Although site groundwater is not planned for future potable use, the potential risks associated with manganese and zinc if the groundwater were used as drinking water were evaluated in the HHRA. They were evaluated because all usable groundwater must be restored to beneficial use, regardless of the current use, and also because of the proximity of several drinking water sources to APG. Manganese and zinc are not classified as human carcinogens. The potential for non-cancer health hazards is expressed as a hazard index (HI), which represents the sum of the ratios of the concentrations of COPCs present at a site to the reference doses for those COPCs at which no adverse health effects are expected to occur. Therefore, an HI less than or equal to 1 indicates that no adverse health effects are anticipated to occur. In the HHRA, the maximum concentrations of COPCs were used to calculate His. For the theoretical scenario of future residential use of groundwater from beneath the site, the HI was less than 1 for the resident child receptor. For the adult, the HI was greater than 1 (HI = 1.7), primarily based on the maximum detected concentration of zinc. However, the maximum detected zinc concentration (16,400 |jg/L; associated with the MPR MRS and sample AARI-MPR-GW-FTA-PZ-02) is not representative of actual groundwater exposure concentrations because it is much higher than the rest of the zinc results and is related to the presence of suspended particulates because the Rl report noted that the sample was observed to have high turbidity (ERT 2014). Using the next highest concentration of zinc (40 |jg/L) in the risk calculations for adult residential use of groundwater results in a HI less than 1. Based on these assessments, human health risk is not likely to be associated with groundwater under the MPR, FDA, and Gas l&D Area MRSs. In addition, all zinc concentrations except the maximum were below the MDE Cleanup Standard for Groundwater. For these reasons, further investigations are not warranted. Ecological Risks: Data that form the basis for the screening-level ecological risk assessment (SLERA) were collected during the Rl. The SLERA was developed to evaluate the chemical contamination risk to wildlife based on direct contact exposures of organisms to the affected media as well as the potential exposure of wildlife through the ingestion of other organisms as food sources. Contaminants of potential ecological concern (COPEC) were identified for subsurface soil and groundwater (via potential interaction with surface water) at the MPR, FDA, and Gas l&D MRSs and for sediment and surface water at the FDA and MPR MRSs. For benthic and aquatic organisms, site metals concentrations in sediment and surface water could pose a potential for risk to individual organisms at the maximum detected concentrations. However, the maximum detected concentrations are not representative of the exposure concentrations for the benthic and aquatic organisms in the ponds and stream at the golf course. In addition, for some constituents, concentrations are similar to background concentrations. In summary, the COPECs detected in the site media at the three MRSs are not likely to have significant ecological effects. A brief discussion of the media and COPECs follows. Subsurface Soil—The concentrations of several metals (antimony, chromium, lead, manganese, and mercury) in subsurface soil were greater than conservative ecological SSLs. These results Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 23 April 2023 indicate that there is a potential for ecological effects. Further assessment of subsurface soil was included in a toxicity reference value (TRV) analysis. Based on the conservative nature of the screening levels and the assumptions used in the TRV analysis, the detected concentrations of metals in site subsurface soil are not likely to have adverse ecological effects. Sediment—The concentration of lead detected in one sediment sample was greater than the sediment screening level. However, the concentration was less than site-specific background. Therefore, the risk assessment determined that lead in sediment was not a concern. Surface Water— Concentrations of aluminum, arsenic, copper, iron, lead, manganese, and mercury in surface water were above the ecological screening levels; therefore, these metals were identified as surface water COPECs. Further assessment of the potential for adverse effects to aquatic organisms from exposure to these metals was conducted by comparing maximum concentrations to NAWQC or another appropriate benchmark if a NAWQC value was not available. Maximum concentrations of aluminum, copper, iron, lead, and manganese were greater than NAWQC. However, with the exception of copper, concentrations of these COPECs were within the range of site-specific background concentrations. Therefore, the risk assessment determined that the concentrations of these metals in surface water were not of ecological concern. While the maximum concentration of copper was greater than the NAWQC and site- specific background, all other copper concentrations were less than the NAWQC. Because aquatic organisms will not be exposed to only the maximum concentration, the risk assessment concluded that adverse effects from exposure to copper throughout the surface water bodies were unlikely. Groundwater (via potential interaction with Surface Water)—Concentrations of metals detected in groundwater were compared to surface water screening levels. Concentrations of aluminum, copper, iron, lead, manganese, nickel, and zinc in groundwater were above the ecological screening levels. The highest concentrations of the COPECs were found in a single sample, which had been observed to have high turbidity and is from a well located outside and downgradient of the MRSs. An assessment of the groundwater and surface water elevations indicated that groundwater is unlikely to be affected by surface water. In addition, the ecological surface water screening levels are developed for the most sensitive aquatic receptors, which are not likely to be present in groundwater. Thus, the SLERA concluded that groundwater is not likely to present unacceptable ecological risks at the MRSs. Ecological Risks Summary—The assessment of the potential for risks to site receptors using TRVs and with consideration of background levels of metals in soil, sediment, and surface water, indicated that ecological risks associated with past Army activities are not likely at the Ruggles Golf Course. MC Risk Summary: No further action is recommended for MC as the concentration of constituents are below background, below regulatory standards, and/or do not present an unacceptable risk to human health or the environment. 2.7.2 MEC Concern Hazard Assessment An explosive hazard assessment was conducted using the MEC Hazard Assessment (MEC HA) to assess potential explosive hazards to human receptors. The MEC HA structure assigns numeric values associated with input factors to generate scores describing the hazards associated with MEC. The MEC HA technical framework consists of three elements: Input Factors, Structure, and Output (USEPA 2006, 2008a). This framework uses information in terms Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 24 April 2023 of explosive hazard components and assigns weighting factors to score the combination of input factors, resulting in an output describing the explosive hazard level category of the MRSs. The MEC HA is structured around three components of a potential explosive hazard incident: • Severity: The potential consequences (e.g., death, severe injury, property damage) of MEC detonating • Accessibility: The likelihood that a receptor will be able to encounter MEC • Sensitivity: The likelihood that a receptor will be able to interact with MEC such that it will detonate. The MEC HA methodology was used during the Rl (ERT 2014). MEC Risk Summary: MPR MRS—No evidence of MEC was found on the MPR MRS during the Rl; therefore, a MEC HA was not performed. FDA MRS—One MEC item was recovered in the FDA MRS demolition pit. The MEC HA included the 81mm illumination round found during the Rl as well as a 105mm HE projectile, which was the munition with the greatest fragmentation distance (MGFD) identified in the Explosives Site Plan (ERT 2012) and the largest of the items historically found at the MRS. The MEC HA includes a worst-case evaluation of the potential MEC items historically found and, therefore, potentially present at the MRS. The FDA MRS scored 640, Hazard Level 3 (moderate hazard potential). The MRS score is a function of the size and location of the one MEC item found during the Rl. Gas l&D Area MRS—There is no potential for MEC at the Gas l&D Area MRS; therefore, a MEC HA was not performed. The MEC CSM (Figure 3) indicates that there is a potentially complete exposure pathway for MEC in the subsurface of the MPR and FDA MRSs for intrusive activities by construction workers. The results of the Rl and FS indicate that further action is necessary to address MEC contamination in the MPR and FDA MRSs. 2.7.3 Basis for Taking Action MC: No action is recommended for MC in the three MRSs as no human health risk or ecological risks were identified. MEC: No action is recommended for MEC in the Gas l&D Area MRS as no explosive hazards were identified. Further action is necessary to protect public health or welfare from potential MEC hazards in the MPR and FDA MRSs. 2.8 Remedial Action Objectives There are no unacceptable MEC or MC risks to human health and the environment at the Gas l&D Area MRS; therefore, no actions are required, and Remedial Action Objectives (RAOs) were not developed for that MRS. The Gas l&D Area MRS is excluded from Section 2.9 through Section 2.13 in accordance with the USEPA guidance for completion of RODs. There are no unacceptable MC risks to human health and the environment at the MPR and FDA MRSs; therefore, RAOs for MC were not developed. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 25 April 2023 The general goal of a MEC remedial action is to reduce explosives hazards to ensure the protection of human health, public safety, and the environment. The specific RAO for the MPR MRS and FDA MRS is: Prevent public, APG personnel, contractor/maintenance worker, visitors/trespasser, and recreational user exposure to MEC while maintaining the intended future land use of a golf course. 2.9 Description of Alternatives This section summarizes the two remedial action alternatives for the MPR and FDA MRSs that were analyzed in the FS (Bay West LLC 2017). These alternatives are listed in Table 6 and are summarized in Sections 2.9.1 and 2.9.2. Table 6. MPR and FDA MR .S Remedial Action Alternatives Designation Description Alternative 1 No Action Alternative 2 Land Use Controls A third alternative, MEC Clearance to Achieve UU/UE, was also evaluated in the screening of alternatives but was not retained for detailed analysis and comparative analysis against other alternatives in the FS. Under Alternative 3, every effort would be made to find, remove, and destroy any MEC that remains below the ground at the MRSs. However, complete removal may not be possible with current technologies due to the historical placement of fill material, which would limit the ability to locate MEC at its anticipated depth as well as beneath existing buildings and other improvements. Furthermore, the anticipated costs to achieve UU/UE through MEC clearance would be very high. The risk of MEC encounters after removal would be very low but not zero. As such, LUCs would still be required for the alternative to be protective. Therefore, because the costs associated with Alternative 3 would be excessive compared to its overall effectiveness and implementability, Alternative 3 was not retained in the FS for detailed analysis. 2.9.1 Alternative 1—No Action In accordance with the NCP, a No Action alternative must be developed as a baseline to compare against other alternatives. In a CERCLA FS evaluation, a No Action alternative equates with a determination to do no remediation and place no controls on land use or activities on the property. The No Action alternative also does not consider any existing controls, if present. Site access is assumed to be unrestricted and there are no limitations on current or future site use or activities. Therefore, Alternative 1, No Action, involves no active response or controls to locate, remove, dispose of, or limit the exposure to any MEC potentially present at the MRS. This alternative provides a baseline for comparison of other response alternatives. It assumes continued use of the MRS in its present state. If the potential exposure and hazards associated with the MRS are compatible with current and future developments in the area, then No Action may be warranted. The Army would respond to any future MEC discovery, regardless of whether the MRS is designated for No Action. 2.9.2 Alternative 2—Land Use Controls for the MPR and FDA MRSs Alternative 2 includes legal and education LUCs to manage remaining hazards at the MPR and FDA MRSs. The hazard is MEC potentially present at 2 ft bgs or greater. No additional active remediation would be performed at the MRSs. The LUCs include: Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 26 April 2023 • Legal Controls — Safety Excavation Permit Program — Prohibition on Residential Use — Contractor Control Policies — Construction Support • Educational Outreach — Public Notices — Community Awareness Meetings — Letter Notifications, Informational Pamphlets, and Fact Sheets — Formal Education Sessions. The MRSs will be formally incorporated into the APG Base Master Plan and review process, which includes a review of any construction plans and construction support. UXO support for any construction or other intrusive activities will be required. Because subsurface MEC may remain, training and awareness programs will be implemented, annual inspections will be performed, and CERCLA Five-Year Reviews will be conducted to assess the site condition and whether the remedy remains protective of human health and the environment. No residential development of the property will be permitted. An MRS Prioritization Protocol (MRSPP) Annual Update will be prepared, in accordance with the requirements of 32 Code of Federal Regulations (CFR) Part 179. The LUC alternative focuses on reducing human exposure to MEC by managing the activities occurring at the MRSs. It will include: • Access and land use restrictions that limit access and restrict activities • Administrative controls on land use through deed and zoning restrictions • Educational information to manage and reduce community exposure to hazards • Construction support requirements. The MRSs will be formally incorporated into the APG Base Master Plan and review process, which includes a review of any construction plans and construction support. The MPR and FDA MRSs will remain at their current status, which consists of MEC potentially present at 2 ft bgs or greater. No remediation will be performed at the MRSs. 2.10 Comparative Analysis of Alternatives A detailed analysis of the individual alternatives was performed and considered each of the nine evaluation criteria specified in NCP §300.430(e)(9)(iii); this analysis is summarized in Table 7. The major objective is to evaluate the relative performance of the alternatives with respect to the nine evaluation criteria so that the advantages and disadvantages of each are clearly understood. The nine evaluation criteria fall into three groups, threshold criteria, primary balancing criteria, and modifying criteria: • Threshold criteria are requirements that each alternative must meet to be eligible for selection. • Primary balancing criteria are used to weigh major trade-offs among alternatives. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 27 April 2023 • Modifying criteria may be considered to the extent that information is available during the RI/FS but are fully considered only after public comments are received on the Proposed Plan. A comparative analysis was then performed so that the advantages and disadvantages of each alternative could be examined relative to each other and so that key differences in the alternatives could be identified, thus providing a framework for selection of an appropriate remedy for the site. This section summarizes how well each alternative satisfies each evaluation criterion and indicates how each alternative compares to the other. A relative ranking of the alternatives against the nine criteria is shown in Table 8, followed by a brief discussion for each criterion. A detailed description can be found in the FS Report (Bay West LLC 2017). Table 7. Evaluation Criteria for Superfund Remedial Alternatives THRESHOLD CRITERIA Overall Protection of Human Health and the Environment determines whether an alternative adequately eliminates, reduces, or controls threats to public health and the environment through institutional controls, engineering controls, or treatment. Compliance with Applicable or Relevant and Appropriate Requirements (ARARs) evaluates whether an alternative meets the requirements of Federal and more stringent State environmental statutes and regulations, other State facility siting laws, and other requirements to be considered (TBC) that pertain to the site, or whether a waiver is justified. PRIMARY BALANCING CRITERIA Long-Term Effectiveness and Permanence considers the ability of an alternative to maintain protection of human health and the environment over time. Reduction of Toxicity, Mobility, or Volume of Contaminants through Treatment evaluates the degree to which an alternative uses treatment to reduce the harmful effects of principal contaminants, their ability to move in the environment, and the amount of contamination present. Short-Term Effectiveness considers the length of time needed to implement an alternative and the risks the alternative poses to workers, the community, and the environment during implementation. Implementability considers the technical and administrative feasibility of implementing an alternative, including factors such as the relative availability of goods and services. Cost includes estimated capital and annual operation and maintenance (O&M) costs, as well as present worth cost. Present worth cost is the total cost of an alternative over time in terms of today's dollar value. Cost estimates are expected to be accurate within a range of +50% to -30%. MODIFYING CRITERIA State Acceptance considers whether MDE, as the support agency, agrees with the Army's and the USEPA's analyses and recommendations, as described in the FS and Proposed Plan. Community Acceptance considers whether the local community agrees with the Army's and USEPA's analyses and preferred alternative. Comments received on the Proposed Plan are an important indicator of community acceptance. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 28 April 2023 Table 8. Comparative Analysis of Remediation Alternatives Screening Criterion Alternative 1: No Action Alternative 2: LUCs Overall Protection of Human Health and the Environment No Yes Compliance with ARARs Not evaluated (a) Not applicable Long-Term Effectiveness and Permanence Not evaluated (a) • Reduction of Toxicity, Mobility, and Volume (TMV) through Treatment Not evaluated (a) 0 Short-Term Effectiveness Not evaluated (a) • Implementability Not evaluated (a) • Cost Not evaluated (a) $45,572 State Acceptance Not evaluated (a) Yes Community Acceptance Not evaluated (a) Yes (a) Not evaluated because the No Action alternative was determined to not be protective of human health, which is one of the threshold criteria. • Favorable (Yes for threshold criteria). 0 Moderately Favorable (Partially meets threshold criteria) o Not Favorable (No for threshold criteria). 2.10.1 Threshold Criteria Overall Protection of Human Health and the Environment: Alternative 1 would not be protective because no action would be taken to prevent human exposure to potential MEC. The MPR MRS has a low hazard potential because no MEC was observed at the MRS during Rl activities. Although the probability is low, it is not zero, as MEC could be encountered during intrusive activities (i.e., utility work or construction). Therefore, current or future potential risks to human health or the environment from MEC would not be prevented under Alternative 1. As a result, Alternative 1 would not meet this criterion. Alternative 2 would not impact the potential presence of MEC, but legal and educational programs and construction support would represent an effective control measure to prevent potential contact by human receptors with MEC at the MRSs. Through LUCs, Alternative 2 would provide protection of human health and the environment by eliminating, reducing, and/or controlling the threat of exposure during intrusive activities and would prevent unacceptable changes to the land use, should they be proposed. Because Alternative 1 (No Action) does not meet this threshold criterion, it is not evaluated against the other NCP criteria. Compliance with ARARs and TBCs: There are no chemical-specific, location-specific, or action- specific ARARs associated with MEC for the LUC alternative. However, should MEC be identified during construction support activities, it will be handled in accordance with the ARARs in Table 9. 2.10.2 Balancing Criteria Long-Term Effectiveness and Permanence: Alternative 2 would be effective and permanent, assuming the cooperation and active participation of the Army's tenants. The LUCs required Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 29 April 2023 under Alternative 2 would be effective in preventing human exposure to MEC presenting an unacceptable risk in the long-term. Reduction of TMV through Treatment: Reduction of TMV through treatment refers to the anticipated performance of the treatment technology used in a remedy. Toxicity is generally not applicable to MEC. Alternative 2 would not reduce the TMV of MEC through treatment, and therefore does not satisfy this criterion. If MEC were identified during construction support activities only a very minor reduction in TMV through treatment, if any, would occur. Short-Term Effectiveness: For Alternative 2, LUCs can be put into place within 6 months to achieve the RAO, and no MEC removal actions would be taken so there would be no short-term risks to the community or workers. If MEC were identified during construction support activities, engineering controls would be implemented to protect the community and site workers. Table 9. Summary of ARARs for the MPR and FDA MRSs ARAR Citation Description Applicability Chemical-Specific None identified Not applicable Not applicable The HHRA and SLERA demonstrated that COPCs and COPECs present in subsurface soil, sediment, groundwater, and/or surface water at the FDA and MPR MRS do not pose unacceptable risk to human health or the environment. Therefore, there are no chemical-specific ARARs. Location-Specific None identified Not applicable Not applicable No location-specific ARARs are identified for APG-AA. Action-Specific Environmental Performance Standards Subpart X - Miscellaneous Units: 40 CFR 264.601 Miscellaneous units will be required to be located, designed, constructed, operated, maintained, and closed in a manner that will prevent any release that may have adverse effects on human health and the environment. Relevant and Appropriate Relevant and Appropriate if actions require treatment of explosives by open detonation. Sampling and Analysis 40 CFR 261 Code of Maryland Regulations (COMAR) 26.13.03.02 40 CFR 136, App. A, (SW-846sampling methods) Specific requirements for identifying hazardous wastes. Establishes analytical requirements for testing and evaluating solid, hazardous, and water wastes. Applicable Applicable should sampling be required at the MRSs for any reason in the future. These standards apply to identifying hazardous waste. General Remediation 40 CFR 262 COMAR 26.13.03.02 Establishes standards for generators of hazardous waste. Applicable Applicable if hazardous waste is identified. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 30 April 2023 Implementability: The legal and administrative LUCs required under Alternative 2 would be implementable and some LUCs are already in place and could be easily augmented. Cost: The estimated costs for Alternative 2 are listed in Table 10 and Appendix C. Table 10. Summary of Costs Alternative No. Capital Costs 30-Year O&M Costs Net Present Worth 1 $0 $0 $0 2 $2,911 $42,661 $45,572 2.10.3 Modifying Criteria State Acceptance: MDE reviewed and provided comments on the Final FS Report and Proposed Plan. MDE has expressed their support for Alternative 2 (Appendix A). Community Acceptance: During the public comment period on the Proposed Plan, no written comments were submitted to APG from the public. During the Proposed Plan public meeting, no attendees presented comments or questions (Appendix D). Therefore, the Army concludes that the community accepts the preferred remedy as specified in the Proposed Plan. 2.11 Principal Threat Wastes The NCP states a preference for using (to the extent practicable) treatment that reduces the TMV of the principal threat wastes. The principal threat concept refers to source materials present at a CERCLA site that are considered to be highly toxic or highly mobile and that generally cannot be reliably controlled in place or that would present a significant risk to human health or the environment should exposure occur. MEC do not meet the definition of principal threat wastes as migration of these materials from the MPR or FDA MRSs is neither occurring nor is it anticipated. Therefore, there are no principal threat wastes at the MRSs. 2.12 Selected Remedy The Army has selected Alternative 2, LUCs, to manage the remaining hazard at the MPR and FDA MRSs. The hazard is MEC potentially present at 2 ft bgs or greater. No remediation will be performed at the MRSs. However, should MEC be identified during construction support activities, it will be handled in accordance with the ARARs in Table 9. Successful implementation of LUCs is contingent upon the cooperation and active participation of the Army's tenants to protect the public from explosives hazards. The M RSs will be formally incorporated into the APG Base Master Plan and review process, which includes a review of any construction plans and construction support. Long-term implementation of LUCs are the responsibility of the Army. The future land use of the MPR and FDA MRSs as Ruggles Golf Course is expected to remain consistent with current land use. The selected remedy is intended to be the final remedy for the MRSs and does not impact any other areas at the Installation. The Army has also selected No Action as the final remedy for the Gas l&D Area MRS as there are no unacceptable risks to human health or the environment associated with the military use of the property and it meets the conditions for UU/UE. The Army is responsible for implementing the selected remedies specified in this ROD. The Army will exercise their responsibility in accordance with CERCLA and the NCP. A description of the selected remedy for the MPR and FDA MRSs is presented in this section. In accordance with Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 31 April 2023 USEPA guidance, the No Action decision for the Gas l&D Area MRS is not discussed in this section. 2.12.1 Summary of the Rationale for the Selected Remedy Based on the information currently available, the Army believes the selected remedy meets the threshold criteria and provides the best balance of tradeoffs among the other alternatives with respect to the balancing criteria. The Army expects the selected remedy to satisfy the following statutory requirements under CERCLA § 121(b): 1) to be protective of human health and the environment; 2) to comply with ARARs; 3) to be cost-effective; 4) to utilize permanent solutions and alternative treatment technologies or resource recovery technologies to the maximum extent practicable; and 5) to satisfy the preference for treatment as a principal element (or justify not meeting the preference). The preferred alternative does not meet the preference for treatment as a principal element; given the low probability of MEC remaining below the ground, finding and destroying the MEC would not be cost effective. Any potential hazards can be reliably controlled using LUCs. 2.12.2 Description of Selected Remedy LUCs focus on reducing human exposure to MEC by managing the activities occurring at the MRSs. The LUC boundary will consist of the MRS boundaries outlined in Figure 4. The MRSs are maintained areas with no history of MEC being found on the ground surface due to migration from the subsurface. In addition, the MRSs were cleared to 2 ft bgs by EOD personnel, other than the greens and tee boxes. Therefore, the potential for migration of MEC, which has never been reported in the past, is considered unlikely. The Rl confirmed that the probability of MEC encounters is low. Based on information currently available, the LUC remedy provides the greatest benefit for the expected costs and meets the RAO. The selected remedy is necessary to protect public health and welfare or the environment from potential exposure to potential MEC. The boundaries for the MPR MRS and FDA MRS LUCs are the MRS boundaries depicted on Figure 2. The Army is responsible for implementing, maintaining, reporting on, and enforcing the LUCs. Transfer of this responsibility is not expected; however, if the Army does transfer these procedural responsibilities to another party by contract, property transfer agreement, or through other means, the Army shall retain ultimate responsibility for remedy integrity. APG's existing LUCIP will be updated to include details for implementation of LUCs at the MRSs. This plan provides an extensive list of practices that are applicable to the entire installation and specific LUCs implemented by the Installation where land is unsafe for UU/UE. LUCs that will be implemented for the MPR and FDA MRSs include legal and educational controls, as described below. Legal Controls: • Safety Excavation Permit Program: APG Regulation 385-7 addresses requirements for MEC construction support during excavation and other intrusive work throughout APG. The APG Base Master Plan and the geographical information system (GIS) will be annotated to show that LUCs are required at these APG-AA MRSs. The Master Plan will be used to review proposed actions in the APG-AA MRSs. In conjunction with this, the APG Directorate of Public Works will review the Base Master Plan and GIS to determine whether future projects are consistent with the LUCs at the MPR and FDA MRSs. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 32 April 2023 • Contractor Control Policies: Contractors performing intrusive activities on the MRSs that have the potential to contact MEC will be required to receive training. The DoD educational message for explosive safety is referred to as "the 3Rs": Recognize, Retreat, and Report any munitions that are encountered while performing maintenance, improvement, or construction activities on their property. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 33 April 2023 Figure 4 - Munitions Response Sites LUC Boundaries Aberdeen Area, Aberdeen Proving Ground, MD Legend ^ Monitoring Well A Survey Monument Road Phillips AAF Stream |_7" j Historic Demo Pit I I LUC Boundary -- New Buildings ¦ (2011) Soil Pile (2011) Pond Golf Fairways Building [ a Wooded Areas Area Shown in Main Map Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 34 April 2023 • Construction Support: When intrusive activities occur at the MRSs, UXO construction support will be performed. Discussions with APG staff indicated that they have provided UXO construction support activities at the MRSs in the past and will continue to do so as needed. UXO construction support will be used to ensure the safety of workers and the public if MEC items are discovered at the MRSs. In accordance with DoD 6055.09-M (DoD 2008), the level of construction support changes in relation to the location and the probability for encountering potential MEC. Each activity occurrence will be reviewed with the APG Safety Office through the safety excavation permit program to ensure the appropriate support is provided based upon the type of activity planned. As the MPR and FDA MRSs have been determined to have a low probability of encountering MEC, it is anticipated that UXO-qualified personnel will provide support either on an on-call basis to respond to MEC that were incidentally encountered, or on a standby basis to monitor construction activities. Educational Controls: Educational outreach will comply with the APG Community Relations Plan (CRP) that is periodically reviewed (every 5 years) for effectiveness in reaching the public. • Public Notices: In accordance with 40 CFR § 300.430(f)(6), notices will be placed in the local newspapers to notify the public of selection of a final remedy and if any changes to the remedy occur. • Community Awareness Meetings: APG has a Restoration Advisory Board (RAB). The RAB works with APG on matters related to APG's environmental cleanup program. The RAB's responsibilities include reviewing Army documents and plans, working with the Army to develop cleanup priorities, and sharing information with and soliciting feedback from members of the community. The RAB meets six times per year and is open to the public. • Letter Notifications. Informational Pamphlets, and Fact Sheets: Development and distribution of informational materials to periodically provide awareness to property owners and town authorities of the presence of munitions. Informational materials are developed and shared annually beginning at the onset of LUC implementation and distribution is later reduced to once every 5 years if the reduced schedule is determined to be acceptable during the 5-year review. In addition, informational materials will be made available to users of the golf course. • Formal Education Sessions: Formal educational sessions will be held to train employees (e.g., grounds crew) at the golf course on the recognition of munitions and procedures to follow should MEC be identified. 2.12.3 Annual Inspections The Army will ensure that annual inspections are performed to evaluate the effectiveness of the LUCs. The details of the annual inspections will be specified in the LUCIP as part of the Remedial Action Work Plan. Inspection forms will be completed during each annual inspection, and the findings of the inspections will be summarized in annual LUC inspection reports. 2.12.4 Comprehensive Environmental Response. Compensation, and Liability Act Five-Year Reviews The potential for MEC remains under the selected remedy for the MPR and FDA MRSs. Therefore, CERCLA requires the review of the remedial action no less than every 5 years to Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 35 April 2023 determine if the selected remedy for the MRSs continues to be protective of human health and the environment. The 5-year reviews will include an assessment of the data generated in the annual inspections, an assessment of the effectiveness of the CRP, site interviews, a site visit/inspection, and a report documenting the results of the review. The report may include recommendations for additional actions or modifications to the management approach, as necessary. Recurring reviews will be completed by the Army and will include the following general steps: • Prepare Recurring Review Plan • Establish project delivery team and begin community involvement activities • Review existing documentation • Identify/review new information and current site conditions • Prepare preliminary Site Analysis and Work Plan • Conduct site visit • Prepare Recurring Review Report. 2.12.5 Summary of Estimated Remedy Costs A detailed cost estimate from the FS (Bay West LLC 2017) is provided in Appendix C and is based on the best available information regarding the anticipated scope of the selected remedy. A summary of the estimated costs associated with implementation of the selected remedies is as follows: • Capital Costs: $2,911 • 30-YearO&M: $42,661 • Net Present Worth: $45,572. The Office of Management and Budget Circular A-94 was updated in November of 2016, signed on December 12, 2016, and the Real Discount Rate for a 30-year Treasury Note or Bond is 0.7%. Estimated project costs may go up or down depending on this rate. LUCs and annual inspections were developed in the FS to assist in developing estimated costs. The legal and education outreach program, and inspection components will be specified in the work plans (remedial action work plan, LUC plan, CRP, long-term monitoring and maintenance plans). Changes in the cost elements may occur as a result of new information and data collected during the implementation of the selected remedy. Major changes to the selected remedy will be documented in the form of a memorandum in the Administrative Record file, an Explanation of Significant Differences, or a ROD Amendment, as appropriate. This is an order-of-magnitude engineering cost estimate that is expected to be within +50% to -30% of the actual project cost. 2.12.6 Expected Outcomes of Selected Remedy Implementation of the selected remedy will address the immediate exposure risks to potential subsurface MEC in the MPR and FDA MRSs. Currently, the FDA MRS scored 640, Hazard Level 3 (moderate hazard potential) based on one MEC item recovered in the FDA MRS demolition pit. The MEC HA included the 81mm illumination round found during the Rl as well as a 105-mm HE projectile, which was the largest of the items historically found at the MRS. Since no additional active remediation will be performed at the MRSs, the MEC HA score will not change. Therefore, UU/UE will not be achieved. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 36 April 2023 Implementation of the selected remedy will support the current and reasonably anticipated future land uses as described in Section 2.6. LUCs will provide measures to inform the public and site users about avoidance of MEC. Annual inspections will be performed, including surveying the site for MEC items that may have migrated to the surface because of erosion, frost heave, or stream transport, minimizing the potential for future contact between MEC and human receptors. Construction support with MEC clearance and CERCLA Five-Year Reviews will be performed to determine if the selected remedy is and will remain protective of human health and the environment. 2.12.7 Green Remediation Green remediation is the concept of reducing the environmental impacts of common investigation and remediation activities. The application of green remediation options involves identifying best management practices (BMPs) that are applicable to the project and the phase of the project, as well as evaluating more sustainable alternatives. There is a multitude of environmental, social, and economic BMPs that can be applied to the different phases of remediation. Consistent with the USEPA guidance, Green Remediation: Incorporating Sustainable Environmental Practices into Remediation of Contaminated Sites (USEPA 2008b), and Methodology for Understanding and Reducing a Project's Environmental Footprint (USEPA 2012), the Army will evaluate the use of sustainable technologies and BMPs with respect to any remedial alternative selected for the site. In addition, the Army will review the Maryland Department of Labor and Industry BMPs when considering remediation alternatives at the MRSs. Examples are as follows: • Minimize impacts to natural resources • Identify recycling and reuse options • Maximize renewable energy use • Use local labor and resources • Reuse unimpacted soil • Use clean diesel fuel and technologies • Reduce greenhouse gas emissions • Use low carbon technologies • Develop a materials management plan • Utilize refurbished equipment when feasible. 2.12.8 Remedial Design A LUC Remedial Design will be prepared as the land use component of the Remedial Design. Within 90 days of ROD signature, the Army shall prepare and submit to EPA for review and approval a LUC remedial design that shall contain implementation and maintenance actions, including periodic inspections. 2.13 Statutory Determinations This section confirms that the selected remedy attains the mandates of CERCLA § 121 and, to the extent practicable, the NCP. Under CERCLA § 121 and NCP § 300.430(f)(5)(ii), the lead agency must select a remedy that protects human health and the environment, complies with ARARs, is cost-effective, and uses permanent solutions and alternative treatment technologies or resource recovery technologies to the maximum extent practicable. In addition, CERCLA also includes: 1) a preference for remedies that employ treatments that permanently and significantly reduce the TMV of hazardous substances, pollutants, or contaminants and 2) a preference for practical treatment technologies versus offsite disposal of untreated wastes. Periodic 5-year reviews are required if the remedy will result in hazardous substances remaining in place above Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 37 April 2023 levels allowing for UU/UE. The following sections discuss how the selected remedy meets these statutory requirements. 2.13.1 Protection of Human Health and the Environment The selected remedy (Alternative 2, LUCs) will protect human health and the environment by mitigating contact with potential residual subsurface MEC. No MC hazards or risks to the environment are present at the MRSs. 2.13.2 Compliance with Applicable or Relevant and Appropriate Requirements As discussed in Section 2.10.1, remedial actions must comply with both federal and state ARARs. There are no chemical-specific, location-specific, or action-specific ARARs associated with MEC for the LUC alternative. However, should MEC be identified during construction support activities, it will be handled in accordance with the ARARs in Table 9. 2.13.3 Cost Effectiveness In the Army's judgment, the selected remedy is cost-effective and represents a reasonable value for the money to be spent. In making this determination, the following definition was used: "A remedy shall be cost-effective if its costs are proportional to its overall effectiveness" [40 CFR 300.430(f)(1)(ii)(D)]. Overall effectiveness was evaluated by assessing three of the five balancing criteria used in the detailed analysis of the alternatives: 1) long-term effectiveness and permanence, 2) reduction in TMV through treatment, and 3) short-term effectiveness. Overall effectiveness was then compared to costs to determine cost-effectiveness. The relationship of the overall effectiveness of the selected remedy was determined to be proportional to its costs. Therefore, the selected remedy represents a reasonable value for the money to be spent. The estimated net present value of capital and O&M costs of the selected remedy (in 2016 dollars) is $45,572. 2.13.4 Utilization of Permanent Solutions and Alternative Treatment Technologies to the Maximum Extent Practicable The Army has determined that the selected remedy represents the maximum extent to which permanent solutions and treatment technologies can be utilized in a practicable manner at the MRSs. The Army has determined that the selected remedy provides the best balance of trade- offs in terms of the five balancing criteria, while also considering the statutory preference for treatment as a principal element and bias against offsite treatment and disposal and considering State and community acceptance. The NCP recognizes that some contamination problems will not be suitable for treatment and permanent remedies. For the MPR and FDA MRSs, there is no permanent treatment other than physical removal of the potential residual MEC should MEC be found during construction support activities. The selected remedy for the MRSs addresses potential residual MEC in subsurface soils, which is the hazard at the MRSs. The selected remedy satisfies the criterion for long-term effectiveness by maintaining LUCs that have been historically effective and reliable and are expected to remain so in the future. The effectiveness of the existing LUCs will be enhanced under the selected remedy. The selected remedy does not present short-term risks. There are no special implementability issues associated with the selected remedy. While the selected remedy does not provide a permanent solution, MEC discovered at the MRSs will be removed permanently. LUCs will be required indefinitely or until such a time as it is determined that there are no residual hazards present. Alternative treatment technologies were not applicable to the MRSs. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 38 April 2023 2.13.5 Preference for Treatment as a Principal Element The NCP establishes the expectation that treatment will be used to address the principal threats posed by a site wherever practicable—40 CFR 300.430(a)(1)(iii)(A). The selected remedy for the MPR and FDA MRSs does not provide for treatment; however, as anomalies are discovered during construction support activities, they are removed after inspection by APG EOD personnel. Consequently, a minor reduction in MEC, if present, may occur during implementation of the selected remedy. Treatment technologies for MEC were not recommended because the low probability of MEC remaining below the ground makes finding and destroying the MEC prohibitively expensive. Any remaining hazards can be reliably controlled using LUCs. 2.13.6 Five-Year Review Requirements Because hazards may remain in the MPR and FDA MRSs that do not allow for UU/UE, CERCLA Five-Year Reviews will be conducted to assess the implementation and performance of the remedy to determine whether the remedy continues to remain protective of human health and the environment. Therefore, in accordance with NCP § 300.430(f)(4)(H), a statutory review will be conducted within 5 years of initiation of remedial action to ensure that the remedy is, or will be, protective of human health and the environment. 2.14 Documentation of Significant Changes The Proposed Plan for the MRSs was released for public comment on 18 March 2022. The Proposed Plan identified Alternative 2—LUCs—as the selected remedy for the MPR and FDA MRSs to address the MEC hazards. The Proposed Plan also documented No Action for the Gas l&D Area MRS. The public did not provide comments on the Proposed Plan that led to a change in the selected remedies. Thus, it was determined that no significant changes to the Preferred Alternatives, as originally identified in the Proposed Plan, were necessary or appropriate. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 39 April 2023 3.0 RESPONSIVENESS SUMMARY This section provides a summary of the public comments regarding the preferred alternative presented in the Proposed Plan for the APG-AA MRSs and the Army's response to those comments. At the time of the public review period, the Army's preferred alternative was Alternative 2, LUCs, for the FDA and MPR MRSs to address the MEC hazards. The Proposed Plan also documented No Action for the Gas l&D Area. No changes to the preferred alternatives were made as a result of the public comments received. 3.1 Stakeholder Comments and Lead Agency Responses The Proposed Plan for the FDA, MPR, and Gas l&D Area MRSs was made available to the public on 18 March 2022. The availability of this document was published in the Aegis, the Cecil Whig, and the Kent County News, on 18 March 2022 (Appendix B) with a 30-day public comment period from 21 March 2002 to 20 April 2022. The Army and USEPA have consulted with MDE, the support regulatory agency, and they concur with the selected remedy. A copy of the MDE letter is included in Appendix A. One written comment on the PP was received from MDE during the public comment period. A summary of the comment and the Army's response are presented below; the complete comment and response are provided in Appendix D. No other written comments were received during the public comment period, and no comments were received during the public meeting. There were no major issues raised by stakeholders during the public comment period or during the public meeting. Therefore, there were no changes to the preferred alternative. Details on the implementation of the selected remedy will be specified in work plans (i.e., updates to the APG LUCIP and CRP). Stakeholders will be invited to participate in planning meetings for the development and review of these plans. MDE provided one written comment on the PP on 15 April 2022 (Appendix D). The comment discusses MDE's Cleanup Standards for Soil and Groundwater and USEPA's RSLs, both of which are mentioned in the PP. The comment asks that references to the MDE Cleanup Standards be removed and that the USEPA RSLs be referenced instead. The Army's response indicates that the PP mentions the MDE Cleanup Standards when summarizing the findings of historical investigations because the Cleanup Standards are comparison values used in those investigations. The historical investigations, particularly the human health risk assessments, also used USEPA RSLs. Because the PP is summarizing historical documents and the comparison values used in the historical documents, no changes to the PP were made. 3.2 Technical and Legal Issues No technical or legal issues regarding the Proposed Plan were identified during the public meeting and/or public comment period. This ROD will be added to the Administrative Record file after it is signed. In addition, a notice of the availability of the ROD will be published in the Aegis, the Cecil Whig, and the Kent County News in accordance with NCP § 300.430(f)(6). Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 40 April 2023 4.0 REFERENCES Aberdeen Proving Ground (APG). 2008. Preliminary Assessment: Former Demolition Area at Ruggles Golf Course. Bay West LLC. 2017. Military Munitions Response Program Feasibility Study Aberdeen Proving Ground - Aberdeen Area Munitions Response Sites. June. Department of Defense (DoD). 2008. DoD Manual 6055.09-M, DoD Ammunition and Explosives Safety Standards, Volume 8, Glossary. 29 February. EA Engineering, Science, and Technology, Inc.. 2011. Aberdeen Proving Ground Western Boundary Study Area, Operable Units 2 and 3 Remedial Investigation Report. Draft Final. February. ERT, Inc. (ERT). 2012. MMRP Remedial Investigation Work Plan. Remedial Investigation, Aberdeen Proving Ground - Aberdeen Area, Harford County, Maryland. January. ERT. 2014. Final MMRP Remedial Investigation Report, Multi-Purpose Range, Former Demolition Area, and Gas Identification and Detonation Area at Aberdeen Proving Ground- Aberdeen Area, Harford County, Maryland. December. Malcolm Pirnie. 2010. Final Addendum to Site Inspection Report, Aberdeen Proving Ground, Maryland. January. MDE. 2010. Facts About...Swann Park. Updated 21 May 2010. Available at: https://mde.maryland.gov/programs/ResearchCenter/ReportsandPublications/Documents/ww w.mde. state. md.us/assets/document/Swann_Park_Fact_Sheet_05_21.pdf. MDNR. 2002. Family-Level Key to the Stream Invertebrates of Maryland and Surrounding Areas. National Oceanic and Atmospheric Administration. 2012. National Weather Services, NOWData. Accessed on January 23, 2012 at http://www.nws. noaa.gov/climate/xmacis. php?wfo=lwx. Office of Management and Budget. 2016. Circular A-94 Appendix C, November 2016, Real Interest Rates on Treasury Notes and Bond of Specified Maturities (in percent), 30-Year. Retrieved from https://obamawhitehouse.archives.gov/omb/circulars_a094 URS Corporation. 2007. Stakeholder Final Historical Records Review, Aberdeen Proving Ground, Maryland. July. U.S. Army. 2022. Proposed Plan for Aberdeen Proving Ground - Aberdeen Area Munition Response Sites, Aberdeen, Maryland. Final. March. U.S. Census. 2021. U.S. Census Bureau Quick Facts available at: https://www.census.gov/quickfacts/fact/table/US/PST045221. U.S. Environmental Protection Agency (USEPA). 1999. A Guide to Preparing Superfund Proposed Plans, Records of Decision, and Other Remedy Selection Decision Documents. EPA 540-R-98-031. July. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Page 41 April 2023 USEPA. 2006. Munitions and Explosives of Concern Hazard Assessment Guidance, Public Review Draft, V4. November. USEPA. 2008a. Interim Munitions and Explosives of Concern Hazard Assessment Methodology. USEPA Publication No. 505B08001. October. USEPA. 2008b. Green Remediation: Incorporating Sustainable Environmental Practices into Remediation of Contaminated Sites. EPA 542-R-08-002. Office of Solid Waste and Emergency Response. April. USEPA. 2011. Toolkit for Preparing CERCLA Records of Decision. OSWER 9355.6-10. September. USEPA. 2012. Methodology for Understanding and Reducing a Project's Environmental Footprint. EPA 542-R-12-002. Office of Solid Waste and Emergency Response. February. Aberdeen Area Munitions Response Sites Aberdeen Proving Ground Military Munitions Response Program Record of Decision ------- Appendix A MDE Letters of Concurrence (To be provided in Final Document) ------- Appendix B Affidavits for Public Notice ------- U.S. ARMY INVITES PUBLIC COMMENT ON PROPOSED PLAN FOR THE ABERDEEN AREA MUNITIONS RESPONSE SITES ABERDEEN PROVING GROUND The U.S. Army at Aberdeen Proving Ground (APG) invites the public to comment on its Proposed Plan for the Aberdeen Area Munitions Response Sites. PROPOSED PLAN The Proposed Flan is available for review at http://bit.1v/:VA-MMRP-PP. A comment card and link for submission of written comments is presented in the Proposed Plan. VIRTUAL PUBLIC MEETING APG invites the public to attend a meeting on; DATE: 31 March 2021 TIME: 7:00 p.m. PLACE: Please email Katrina Harris at kharris (/bridaeconsultingcorn.com for information on how to participate via computer or phone. WRITTEN COMMENTS The 30-day public comment period on the proposed action extends from 21 March to 20 April 2022. Written comments, post- marked by 20 April 2022. should be sent to: Mr. Rurik Loder Directorate of Public Works Environments 1 Di vis ion Building 4304. 650 Rodman Road Aberdeen Proving Ground. MI) 21005: or Ms. Andrea Bar bier i, Remedial Project Manager USF.PA. Region Til 1650 Arch Street Philadelphia. PA 19103-2029; or Mr. Russell Ashley, P.G. Maryland Department of the Environment Federal Facilities Section Installation Restoration Program 1800 Washington Boulev ard. Suite 625 Baltimore. MD 21230-1719 PROPOSED ACTION— APG has prepared a IVoposed Plan to address three Munitions Response Sites in the Aberdeen Area of .Aberdeen Proving Ground. These sites include the Multi-Purpose Range. Former Detonation Area, and the Gas Identification and Detonation Area. These sites were used for various training activities during the 1.940's to mid 1950's and the sites were investigated through several inspections and assessments from 2006 until a final Remedial Investigation (RI) Report in 2014. Geophysics, environmental sampling, intrusive investigations, and human and ecological risk evaluations were performed during the RI. There are no unacceptable human health or ecological impacts to soil sediment, surface water, or groundwater from the historical site use and the potential for exposure to munitions and explosiv e of concern is low. Alternatives that were evaluated in a Feasibility Study (l'S) to address the potential for exposure to munitions included No .Action and I.and Use Controls. Land I'se Controls include prohibiting residential use. safety through the Excavation Permit Program, and Educational Outreach. As presented in the IYoposed Plan, the Sites warrant Land Use Controls at the Multi-Purpose Range and Former Demolition Area Sites, and No Action at the Gas Identification and Detonation Area based on the results of the RI l'S and risk assessments. ------- Appendix C Cost Summary ------- APG-AA, Former Demolition Area MRS Alternative 2 COST ESTIMATE SUMMARY I Land Use Controls ISite: Former Demolition Area (FDA) MRS Location: APG-AA Phase: Feasibility Study Base Year: 2016 Capital Costs UNIT Description QTY UNIT COST TOTAL NOTES Public Meeting, LUCIP, APP 1 LS $ 2,079 $ 2,079 See cost worksheet Project Contingency 25% $ 520 Program Management 15% $ 312 TOTAL CAPITAL COST $ 2,911 I Annual Operation and Maintenance (O&M) Costs UNIT Description QTY UNIT COST TOTAL NOTES Annual Sign Maintenance 60 EA $ 250 $ 15,000 Replace avg of 2 signs per year LUC Inspections 30 EA $ 377 $ 11,295 See cost worksheet Annual Memo Report 30 EA $ 550 $ 16,493 See cost worksh eet TOTAL ANNUAL COST $ 42,788 Periodic Costs UNIT Description QTY UNIT COST TOTAL NOTES Five Year Review 6 EA $ 1,193 $ 7,155 Update every 5 years for 30 years TOTAL PERIODIC COST $ 7,155 TOTAL 30-YEAR O&M COST (2% discount): ( $ 42,661 | Total Present Worth Cost (2% discount):) $ 45,572 | ------- APG-AA, Former Demolition Area MRS Alternative 2 COST WORKSHEET I Land Use Controls (Site: Former Demolition Area (FDA) MRS Location: APG-AA Phase: Feasibility Study Base Year: 2016 Cost Analysis Description UNIT QTY UNIT COST TOTAL NOTES Public Meeting, LUCIP, APP PM 1 HR $ 100 $ 100 Planning Documents for Site Inspections Senior Engineer 6 HR $ 93 $ 558 Assume one document for APG-AA so Junior Scientist 15 HR $ 68 $ 1,014 only a portion of the costs are included SUXOS 2 HR $ 80 $ 170 for this MRS. Word Processor 5 HR $ 48 $ 238 TOTAL $ 2,079 LUC Inspections Truck 0.25 Day $ 175 $ 44 Assume field work for all APG-AA and APG-EA Fuel/Maintenance 1 gallon $ 2 $ 2 MRSs is performed concurrently, providing Analog metal detector 0.25 Day $ 18 $ 5 efficiencies Trimble GPS 0.25 Day $ 55 $ 14 Geologist 1.5 HR $ 135 $ 203 UXOSO/QCS 1 HR $ 110 $ 110 Health and Safety/GC TOTAL $ 377 Annual Memo Report PM 0.5 HR $ 100 $ 50 Assume one document for APG-AA Senior Engineer 1.5 HR $ 93 $ 140 so only a portion ofthe costs are Junior Scientist 4 HR 00 <0 $ 270 included for this MRS. SUXOS 0.5 HR $ 85 $ 42 Word Processor 1 HR $ 48 $ 48 TOTAL $ 550 5-year Review PM 1 HR $ 100 $ 100 Assume one document for APG-AA Senior Engineer 4 HR $ 93 $ 372 so only a portion ofthe costs are Junior Scientist 8 HR $ 88 $ 541 included for this MRS. SUXOS 1 HR $ 85 $ 85 Word Processor 2 HR $ 48 $ 95 TOTAL $ 1,193 ------- APG-AA, Multi-Purpose Range MRS Alternative 2 Land Use Controls PRESENT WORTH SUMMARY Site: Multi-Purpose Range (MPR) MRS Location: APG-AA Phase: Feasibility Study Base Year: 2016 Present Value Analysis Annual Percentage Rate YR Capital 2% Periodic Cost Total Costs Present Worth oaM Annual 0 $2,911 - - $2,911 $2,911 1 - $1 426 - $1,426 $1,398 2 - $1 426 - $1,426 $1,385 3 - $1 426 - $1,426 $1,371 4 - $1 426 - $1,426 $1,358 5 - $1 426 $ 1,193 $2,619 $2,469 6 - $1 426 - $1,426 $1,332 7 - $1 426 - $1,426 $1,319 8 - $1 426 - $1,426 $1,306 9 - $1 426 - $1,426 $1,294 10 - $1 426 $ 1,193 $2,619 $2,352 11 - $1 426 - $1,426 $1,269 12 - $1 426 - $1,426 $1,257 13 - $1 426 - $1,426 $1,245 14 - $1 426 - $1,426 $1,233 15 - $1 426 $ 1,193 $2,619 $2,243 16 - $1 426 - $1,426 $1,210 17 - $1 426 - $1,426 $1,199 18 - $1 426 - $1,426 $1,188 19 - $1 426 - $1,426 $1,177 20 - $1 426 $ 1,193 $2,619 $2,141 21 - $1 426 - $1,426 $1,155 22 - $1 426 - $1,426 $1,145 23 - $1 426 - $1,426 $1,134 24 - $1 426 - $1,426 $1,124 25 - $1 426 $ 1,193 $2,619 $2,045 26 - $1 426 - $1,426 $1,104 27 - $1 426 - $1,426 $1,094 28 - $1 426 - $1,426 $1,084 29 - $1 426 - $1,426 $1,074 30 - $1 426 $ 1,193 $2,619 $1,955 TOTALS $2,911 $42,788 $7,155 $52,855 $45,572 ------- Appendix D Summary of Comments Received During Public Comment Period and Army Responses ------- Directorate of Public Works - Aberdeen Proving Ground 1. Version: 1.0 Project: Aberdeen Proving Ground - Aberdeen Area (APG-AA) Document: Proposed Plan for Aberdeen Proving Ground, Aberdeen Area Munitions Response Sites, March 2022 Contract: W91ZLK-13-D-0002 Reviewer: MDE RPM, Russell Ashley, P.G. Section: Federal Facilities Installation Restoration Program Date: 4/15/22 Response By: Affiliation: Date: Item Reference Comment Contractor Response Action MDE RPM, Russell Ashley, P.G.; comment received 15 April 2022 1 General Maryland Department of the Environment Cleanup Standards for Soil and Groundwater references The Maryland Department of the Environment's "Cleanup Standards for Soil and Groundwater" (2018) were specifically developed to support the Voluntary Cleanup Program as well as other programs within the Maryland Department of the Environment for use in lieu of and/or in support of a site specific risk assessment. The guidance specifically states on Page 3 which State programs for which the guidance was intended. The guidance was not intended for use at sites complying with the federal Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). The Maryland Cleanup Standards for Soil and Groundwater establish a cancer risk of lxl0"6 and a hazard quotient of 0.1, similar to screening levels for soil and groundwater at CERCLA sites. However, the Maryland Cleanup Standards for Soil and Groundwater were most recently updated in October 2018, whereas the Regional Screening Level (RSL) tables prepared by the United States Environmental Protection Agency (https://www.epa.gov/risk/regional- screening-levels-rsls) are updated on a much more regular basis (typically once or twice per year). Therefore, please remove all reference and use of the Maryland Department of the Environment's "Cleanup Standards for Soil and Groundwater" from this and future documents, and instead reference the more frequently updated RSL tables. The Proposed Plan mentions the MDE Cleanup Standards when summarizing the findings of historical investigations because the Cleanup Standards are comparison values used in those investigations. The historical investigations, particularly the human health risk assessments, also used USEPA RSLs. Because the Proposed Plan is summarizing historical documents and the comparison values used in the historical documents, no changes to the PP will be made. None ------- |