A.02.17.01 Encl 1 REDACTED RD TS3_CCAN104_12June2023.pdf

Final Remedial Design (100%) CCAN104 GE43T Groundwater Remedial Design Katterbach Kaserne, USAG Ansbach, Germany

U.S. Army Corps of Engineers, Erict

Project reference: W912GB19D0006; Delivery Order W912GB20F0266 Project number: 60641816

12 June 2023

Final Remedial Design (100%) Project reference: W912GB19D0006; Delivery Order W912GB20F0266

Project number: 60641816

Prepared for: U.S. Army Corps of Engineers, Europe District 60641816_RD_CCAN104_12June2023.docx AECOM

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U.S. Army Corps of Engineers, Europe District Konrad-Adenauer-Ring 39 65189 Wiesbaden Germany

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AECOM International, Inc.

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This document has been prepared by AECOM International, Inc. (“AECOM”) for sole use of our client (the “Client”) in accordance with generally accepted consultancy principles, the budget for fees and the terms of reference agreed between AECOM and the Client. Any information provided by third parties and referred to herein has not been checked or verified by AECOM, unless otherwise expressly stated in the document. No third party may rely upon this document without the prior and express written agreement of AECOM.

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Table of Contents

1. Introduction

1.1 Background

1.2 Objectives

1.3 Local Host Nation Correspondence

1.4 USACE Decision Document

1.5 Remediation Documentation

2. Site Description

2.1 Site Description and Layout

3. Data Review

3.1 PFAS Groundwater and Perched Water Results

3.2 Other Parameters Groundwater Results

3.3 Groundwater Pumping Tests

3.4 Estimated Groundwater Capture Zones

3.5 Groundwater Column Tests

4. Preliminaries

4.1 Proposed Clean-up Goals

4.2 Permits and Approvals

4.2.1 Permit according to Water Law

4.2.2 Digging Permit (Utility Clearance)

4.2.3 Photo Permit

4.3 UXO Avoidance

4.4 Site Access

4.4.1 Access to the Installation

4.4.2 Access to the Treatment Area

4.5 Staging / Stockpiling Areas

4.6 Health & Safety Precautionary Measures

4.7 Ambient Air Monitoring in the Working Area

4.8 Management of Waste (IDW)

5. Remedial Design

5.1 Proposed Remediation Technology

5.2 Benefits of the TS3 Location at the Treatment Area

5.3 Water Extraction Area

5.3.1 Groundwater

5.3.2 Perched Water

5.4 Water Extraction Works

5.5 Water Transfer to the Treatment Area

5.6 Excavation Work

5.6.1 Utility Clearance

5.6.2 Excavation and Pipe Installation (General)

5.7 Set-up of the Treatment Area and TS3 – Technical Specifications

5.7.1 Identification of Existing and Proposed Services

5.7.2 Treatment Area Concrete Slab

5.7.3 New Vertical Outlet Shaft (Structure 4)

5.7.4 Locate Existing Drainage Pipe 5

5.7.5 Power Connection to Building 5801

5.7.6 Connection to Outlet Shaft (Pipe 4)

5.8 TS3 Design / Treatment Technology

6. Operation and Maintenance (O&M) of TS3

7. Long Term Monitoring

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7.1 Objectives

7.2 Proposed Groundwater Monitoring Plan

7.3 Groundwater Monitoring Schedule

7.4 Groundwater Sampling Methodology

7.5 TS3 Process and Performance Monitoring

7.6 Laboratory Analysis

7.7 Site Inspection

7.8 Reporting

8. Principal Work Schedule

9. Cost Estimate (REDACTED)

10. References Groundwater Summary Tables (June 2022) Appendix A GWM37/GWM70 Pumping Test Data Appendix B Groundwater Pilot Trial (AECOM, 2023) Appendix C Site Photo Log Appendix D Site Service Plans

Tables (in report) Table 1: Summary of Long-Term Constant Rate Pumping Tests Table 2. Contact Details for Commercial Utility Providers Table 3: Summary of Existing and Proposed Services Table 4. Proposed Groundwater Monitoring Network (long-term) Table 5. Proposed Water Monitoring Schedule during Remediation Project Table 6: Proposed Water Monitoring Schedule during the Remediation Project 1 Table 7. Laboratory Analytical Requirements

Figures (in Appendix) Figure A-1 Overview of the Proposed Service Line to the TS3 Treatment System

Figure A-2 Proposed Service Line – Northern Section

Figure A-3 Proposed Service Line – Central Section

Figure A-4 Proposed Service Line – Southern Section

Figure A-5 Proposed Location and Setup of TS3

Figure A-6 Proposed Extraction Wells

Figure A-7 PFAS Groundwater Concentrations and Estimated Capture Zones for GWM37 & GWM70

Figure A-8 PFAS Concentrations in Perched Water

Figure A-9 Utilities Situation (provisionally)

Figure A-10 As-Built Stormwater System

Figure A-11 Profile View 1

Figure A-12 Profile View 2

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Figure A-13 Proposed Design of Trenches

Figure A-14 Potential Manhole Construction Design

Figure A-15 Potential Construction Design Outlet Shaft (Structure 4)

Figure A-16 Process Flow Diagram of TS3

Figure A-17 Proposed Groundwater Monitoring Well Network

Summary Tables (in Appendix) Table A-1 Groundwater Analytical Results - PFAS

Table A-2 Perched Analytical Results - PFAS

Table A-3 Groundwater Field Parameters

Table A-4 Groundwater Analytical Results - Basic Parameters

Table A-5 Groundwater Analytical Results – CHC, AHC, TPH, others

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List of Acronyms AECOM AECOM International, Inc.

AEDB-CC Army Environmental Database – Compliance-related Cleanup AFFF aqueous film-forming foams AHC aromatic hydrocarbons ARLOC Army Location asl. above sea level (meters) bgl below ground level (meters) °C degrees Celsius CHC chlorinated hydrocarbons cm centimeter DD Decision Document DIN Deutsches Insitut für Normung (German Standard Institute) D.O. Delivery Order DOC dissolved organic carbon DPW Directorate of Public Works EC electrical conductivity EIE end invert elevation EMD Environmental Management Division FFTP Fire-Fighting Training Pit GAC granular activated carbon GFS Geringfügigkeitsschwellenwert (insignificant threshold value) GmbH Gesellschaft mit beschränkter Haftung (limited liability company) GOW gesundheitlicher Orientierungswert (health-oriented criteria) HN Host Nation H4PFOS 6:2-Fluorotelomersulfonic acid HSP Health and Safety Plan K hydraulic conductivity kg kilogram L liter LfU Bayerisches Landesamt für Umwelt (Bavarian State Office for the Environment) m meter m³ cubic meter mg milligram min minute ml milliliter mm millimeter No. number O2 oxygen O&M operation and maintenance OWS oil-water separator PAH polycyclic aromatic hydrocarbons PFAS per- and polyfluoroalkyl substances PFBA Perfluorobutanoic acid PFBS Perfluorobutane suflonic acid PFDeA/PFDA Perfluorodecanoic acid PFHpA Perfluoroheptanoic acid PFHpS Perfluoroheptane sulfonic acid PFHxA Perfluorohexanoic acid PFHxS Perfluorohexane sulfonic acid PFNoA/PFNA Perfluorononanic acid PFOS Perfluorooctane sulfonic acid PFOA Perfluorooctanoic acid PFOS Perfluorooctane sulfonic acid PFOSA Perfluorooctane sulfonamide PFPeA Perfluoropetanoic acid RD remedial design RRB rainwater retention basin SIE start invert elevation T transmissivity

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Temp. temperature TOC total organic carbon TMB trimethylbenzene TPH total petroleum hydrocarbons TS treatment system U.S. United States USACE U.S. Army Corps of Engineers, Europe District USAG U.S. Army Garrison µg microgram WHG Wasserhaushaltsgesetz (water law) % percent

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1. Introduction AECOM International, Inc. (AECOM) has been contracted by the U.S. Army Corps of Engineers, Europe District (USACE) on behalf of the U.S. Army Garrison (USAG) Ansbach, Directorate of Public Works (DPW), Environmental Management Division (EMD) to prepare a Remedial Design (RD) for extraction and remediation of per- and polyfluoroalkyl substances (PFAS) impacted groundwater for the Army Environmental Database Compliance Clean-up (AEDB-CC) site CCAN104 located within the Katterbach Kaserne, Germany (hereafter referred to as “the Site”).

This document presents the RD for the PFAS-impacted groundwater which has been identified at the Site. It includes a review of the available data, the proposed groundwater extraction area, and the features of the treatment system. It is noted that the current approach is for the extracted groundwater to be piped underground for treatment at Treatment System #3 (TS3) which will be located at the Treatment Area to be constructed across the road (north) of Building 5801 (refer to Figure A-1 to Figure A-5). The TS2 related to the groundwater extractions works from the Building 5801 (Hangar 4) area will also be located at the Treatment Area. Therefore, this report should be read in conjunction with the following TS2 design reports:

AECOM International Inc., 31 May 2022. CCAN126 PFAS IRA Ansbach, Sampling Report and Conceptual Preliminary Interim Removal Action (IRA) Design of Groundwater Treatment System TS2. Katterbach Kaserne, USAG Ansbach, Germany. Final (/11/), and

AECOM International Inc., 7 June 2023. Building 5801 – PFAS IRA Ansbach – Remedial Design of the PFAS Treatment System TS2. Katterbach Kaserne, USAG Ansbach, Germany. Final (/14/).

The location of the Site and the Treatment Area are provided in Figure A-1.

This RD requires review and approval by the responsible Water Board Ansbach (Wasserwirtschaftsamt) and the City of Ansbach – Environmental Agency (Umweltamt der Stadt Ansbach) for the purpose of acquiring required extraction and discharge permits for the extraction of groundwater and operation of

TS3.

This project was awarded under Contract No. W912GB19D0006, Delivery Order No. W912GB21F0266.

1.1 Background

The installation was constructed in the 1930s by the “Deutsche Wehrmacht”. The installation has been used by the U.S. Army since 1945 and includes administrative, storage, maintenance, health, housing, and educational facilities, as well as a helicopter airfield.

Previous interviews with base personnel indicate that the former Fire Fighting Training Pit (former FFTP) located south of Building 5508 (Hangar 5) was used for fire training drills using aqueous film-forming foams (AFFF) between 1986 and 2001. The AFFF concentrate used at the former FFTP was known under the trade name “Light Water” and was produced by the 3M company. From these activities, the soils in the area were impacted with PFAS. Over time, the highly mobile PFAS compounds have migrated through the soil and rock profile and impacted the Site’s groundwater.

PFAS investigations at the Site have been ongoing since a request was sent by Host Nation (HN) authorities in a letter dated 29 August 2014. In response to that request, sampling of soil, perched water, groundwater, spring water, and grass clippings have been conducted by different entities on and off-post (e.g., /1/ to /12/).

PFAS impacts to the Site’s soil and groundwater have been identified during various stages of investigations (e.g. /5/, /9/ and /12/). Higher PFAS concentrations in soil eluate (ranging between 50-100 µg/L in some areas) have been reported in the vicinity of the former FFTP (/5/ and /9/). This area is considered to be the main source area and appears to be an ongoing source of impact to the

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Site’s groundwater. Maximum Perfluorooctane sulfonic acid (PFOS) soil eluate concentrations of 420 µg/L (solid matter 27 mg/kg) were reported to be in the topsoil sample (2-10 cm) adjacent to the southwest corner of the former FFTP.

Various stages of site investigations (both onsite and offsite) have identified PFAS impacted groundwater in the area and downgradient of the former FFTP. The extent of the plume was further delineated during the Groundwater Investigation (/12/) with the June 2022 sampling round. Total PFAS concentrations in the central portion of the plume range between 39.9 to 59.2 µg/L in the area of groundwater monitoring wells GWM40, GWM70 and GWM85A (onsite) and GWM01 (offsite).

Groundwater flow direction(s) is yet to be confirmed partly due to the different well construction methodologies adopted and the complex geology/hydrogeology at the Site. Based on the distribution of the highest PFAS groundwater concentrations, groundwater flow from the main source area (i. e., the former FFTP area) is to the northwest.

1.2 Objectives

The objectives of this RD are to provide:

the proposed water extraction area and extraction wells (for groundwater and perched water), the requirements for the proposed water extraction and TS3, including associated cost estimates for construction and operation. The cost estimate will be provided with the Draft Final Remedial Design (95%), the proposed clean-up goals (PFAS), the proposed underground services route between the Site and the Treatment Area (for final approval by the Garrison), and the long-term monitoring requirements for the remediation project.

The overarching objective for the proposed groundwater hydraulic containment and treatment works at the Site is to mitigate the offsite migration of PFAS impacted groundwater and ultimately, in the long term, improve groundwater quality entering Katterbach Creek.

1.3 Local Host Nation Correspondence

The following HN correspondence is noted:

City of Ansbach – Environmental Department (letter dated 4 March 2020 for sites

CCAN104/CCAN126 (/16/):

HN summarized that a conclusive understanding of the local groundwater flow direction had not been established to date. However, due to contaminant migration in a northwesterly direction, groundwater flow direction is assumed to be to the northwest. The City of Ansbach letter required the following works:

Hydraulic containment at the fence line to prevent further (offsite) migration of PFAS via the groundwater pathway, Further clarification and determination of the local groundwater flow regime is requested. This includes the quantification of groundwater recharge / runoff, and

Development of a remediation plan to include the mitigation of the source (soil) and containment of the downward migration via the groundwater pathway.

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City of Ansbach – Environmental Department (letter dated 3 April 2020 for site CCAN104) /17/:

The letter focused on the Feasibility Study (/9/) and is summarized as follows:

the letter requires that the soil and groundwater remediation works be managed separately, the letter agreed with groundwater remediation option G4 (“containment, hydraulic plume control near the downgradient installation boundary”), prior to implementation of the remediation measure, hydrogeological conditions needed to be determined, and in planning for the required groundwater remediation works, additional information was required including results of previous investigations, geology/hydrogeology, delineation of the PFAS plume, pumping tests, and details on the required groundwater extraction wells and the proposed remediation system.

City of Ansbach – Environmental Department (letter dated 8 June 2020 for site CCAN104) /18/:

HN requested the faster implementation of the requested groundwater investigations of the source area, etc. and the implementation of a hydraulic containment at the fence line (as required in /16/ discussed above).

1.4 USACE Decision Document

A Decision Document (DD, /19/) was prepared for the Site and also included CCAN126. The DD can be summarized as follows:

The DD only discusses the required groundwater remediation works and notes that “further studies and investigations are required to select remediation methods for soils” and "a subsequent DD will be developed” for the Site after the completion of the further studies, It notes that “HN agreed with the hydraulic containment remedy for groundwater” in the letter /19/ discussed in Section 1.3, while also noting that “hydraulic control is not a substitute for remediating the source area (i. e., soil remediation)”, and

The remediation method recommended for the Site by the DD is “hydraulic containment and plume control at the downgradient installation boundary”.

1.5 Remediation Documentation

The remediation contractor will be responsible for the following reports:

Application for extraction, treatment, and discharge of groundwater provided to the City of Ansbach for approval, Project-specific Health and Safety Plan (HSP), Waste Management Plan (soil and surface water), and

Erosion and Dust Control Plan (including dust monitoring requirements).

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2. Site Description

2.1 Site Description and Layout

Katterbach Kaserne [ARLOC GE43T] is located approximately five kilometers east of the City of Ansbach, federal state of Bavaria, Germany. The installation consists of two adjacent fenced areas, which are separated by the federal road B14. The area north of the B14 is called "Bismarck Kaserne", the area south "Army Helipad". A fence for the airfield security area and an internal ring road is located in the western portion of the Site. The second (outer) Katterbach Kaserne fence forms the western Site boundary.

The Site is located south of Building 5508 (Hangar 5) in the area of a former FFTP in the western part of the helicopter airfield (Figure A-1).

The former FFTP comprised a cross-shaped concrete basin (1986 through 2001) until it was upgraded in 2001 with a flat concrete pit measuring approx. 15 m x 18 m (its current condition). The pit is equipped with an outlet which is connected to an oil-water separator (OWS) via a 12,000 L holding tank. Further discharge from this area (to the north) also occurs via the airfield stormwater drainage system. Firefighting exercises with film-forming firefighting foams were conducted approximately quarterly until 2000. Fire-fighting training activities resulted in impacts to the soil and groundwater with PFAS at the Site.

The area in the vicinity of the former FFTP is predominantly covered with grass. The ring road was constructed in approximately 2007 and is likely to have involved some movement of soils in this area.

The western facility border is situated approximately 75 m west of the concrete pit.

3. Data Review

3.1 PFAS Groundwater and Perched Water Results

The PFAS groundwater and perched water results, and groundwater field parameters from the June 2022 sampling round (/12/) are provided in Tables A-1 to A-3. The location of the groundwater monitoring wells is detailed in Figure A-7.

The groundwater and perched results at the Site are summarized as follows:

The highest PFAS concentrations in groundwater at GWM78A (390 µg/L total PFAS) are likely related to the close proximity to the former FFTP and, based on the BS06 to BS08 perched water data, the identified highly contaminated perched water in this area, Total PFAS concentrations in the perched water in the BS06 to BS08 area ranged between 1,506 µg/L (BS06) and 316 µg/L (BS07) (refer to Figure A-8), Elevated and similar total PFAS concentrations and constituents at the following wells to the north/northwest of the former FFTP indicate this is the likely central and downgradient portion of the plume (with increasing distance away from the former FFTP, refer to Table A-2 and Figure A-7):

─ GWM01 - 52.5 µg/L, ─ GWM40 - 59.2 µg/L.

─ GWM70 - 45.9 µg/L, and

─ GWM85A - 39.9 µg/L.

The sum of PFOS, Perfluorohexane sulfonic acid (PFHxS), and H4PFOS concentrations in the above wells consistently ranged between 70.9 and 72.4 % of total PFAS.

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During the groundwater pumping tests (refer to Section 3.3), PFAS emissions sampling and analysis was also conducted across the duration of the tests (individual wells). The results are summarized as follows:

GWM70 – PFAS concentrations decreased from 42.6 µg/L to 31.3 µg/L (239 hours) which likely indicates that this well is located near the middle of the plume, GWM71 – PFAS concentrations were variable (due to lower concentrations) and ranged between

0.39 µg/L to 0.88 µg/L (237 hours). The lower concentrations indicate this well is on the edge of the plume, GWM84A – PFAS concentrations decreased from 12.2 µg/L to 5.8 µg/L (240 hours) which likely indicates that this well is located just outside the middle of the plume, GWM84B – PFAS concentrations increased from 1.25 µg/L to 2.03 µg/L (194 hours) which likely indicates some vertical migration of PFAS impacts from the shallower portion of the aquifer (A-aquifer) to the deeper portion (refer to GWM84A above), and

GWM85A – PFAS concentrations decreased from 22.9 µg/L to 16.2 µg/L (145 hours) which likely indicates that this well is located just outside the middle of the plume.

3.2 Other Parameters Groundwater Results

Groundwater samples from the new wells were also tested for the parameters of the Bavarian basic parameter list /29/ and these results are detailed in Table A-4. The electric conductivity was reported to range between 562 and 1,271 µS/cm indicating that the water is most likely groundwater and less influenced by stormwater. In general, there is nothing unusual with the results from the Site.

During the combined GWM37 and GWM70 pumping test, one round of sampling was conducted from the stabilized water flow and tested for additional parameters total petroleum hydrocarbons (TPH) C10- C40 according to H53 standard, polycyclic aromatic hydrocarbons (PAHs), aromatic hydrocarbons (AHC including trimethylbenzenes, TMB), chlorinated hydrocarbons (CHC), cations/anions, total organic carbon (TOC), dissolved organic carbon (DOC) and hardness to fully characterize the water quality and to identify any co-contaminants in the groundwater which may have an impact on the treatment works.

The GWM37 and GWM70 results are detailed in Table A-5, and the main results are summarized as follows:

Sum of Benzene, Toluene, Ethylbenzene and Xylene (BTEX) was reported to be non-detect, TPH C10-C40 was reported to be non-detect (less than 0.1 mg/L), PAH were non-detect and 0.01 µg/L, CHCs were non-detect with the exception of Tetrachloroethene (TCE) concentrations of

3.6 and 11 µg/L, pH was 6.74 and 7.04, TOC was 1.3 and 1.8 mg/L, DOC was 1.2 and 1.4 mg/L, Manganese was 0.003 and 0.014 mg/L, Iron was non-detect (less than 0.005 mg/L), Nitrate was 15 and 43 mg/L, Nitrite was non-detect (less than 0.1 mg/L), and

Electric conductivity was 545 and 1,130 µS/cm.

The above GWM37 and GWM70 results are similar to the results from the Bavarian basic parameters testing from across the monitoring well network detailed in Table A-4.

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Groundwater samples were also collected from GWM37 to GWM40 and analyzed for CHCs in 2015 (/5/). CHC concentrations were all reported to be below the laboratory detection limits.

3.3 Groundwater Pumping Tests

Long term (constant rate) groundwater pumping tests at the Site have been completed in two stages:

Individual wells (February to April 2022) - GWM70, GWM71, GWM84A, GWM84B and GWM85A (further details are provided in the Groundwater Investigation Report (/12/), and

Combined pumping test for GWM37 and GWM70 (August 2022). These two wells were selected for the combined test because they are located within the central portion of the PFAS plume (perpendicular to the plumes central axis) and extraction of the groundwater from these locations would mitigate offsite migration. The data from these works is provided in Appendix A (also refer to Section 3.2).

The interpretation of the above pumping tests is detailed in Table 1 and the pumping test data and evaluation is provided in Appendix A).

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Table 1: Summary of Long-Term Constant Rate Pumping Tests

Well ID Well Depth (m)

Well Diameter

(mm)

Well Type Pumping Test Duration (hrs)

Extracted Volume (m3)

Maximum Drawdown (cm)

Stabilized Extraction

Rate (L/min)

Hydraulic Conductivity (K, m/s)

Transmissivity (T, m2/s)

Individual pumping tests:

GWM70 24.5 125 Fully penetrating

239 222.3 559 15.5 1.02E-5 1.65E-4

GWM71 23.7 125 Fully penetrating

237 199.1 413 14 4.17E-6 5.86E-5

GWM84A 20.2 125 A well 240 86.4 177 6 1.61E-5 9.10E-5

GWM85A 20 125 A well 145 62.4 736 8/7 (changed after 30h)

1.28E-6 1.15E-5

GWM84B 25.8 125 B well 194 116.4 344 10 1.72E-5 5.16E-5

Combined GWM37 and GWM 70 pumping test:

GWM37 17 125 A well and part of B

240 121.6 546 8.4 (average) 4.72E-6 6.98E-5

GWM70 24.5 125 Fully penetrating

240 223.2 538 15.5 7.60E-6 1.12E-4

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3.4 Estimated Groundwater Capture Zones

Based on the combined GWM37 and GWM70 pumping test data, the estimated capture zones for these wells (i. e., under equilibrium conditions) were calculated using the /15/ model and are presented in Figure A-7. The PFAS groundwater concentrations reported across the Site from the June 2022 sampling round (/12/) are also presented on Figure A-7. It is important to note that because GWM37 is not currently a fully penetrating well, the estimated capture zone in Figure A-7 is estimated to be wider than it will be once this well is converted to a fully penetrating well (refer to Section 5.1). Once the well has been drilled and installed deeper (i. e., replaced with a new well), it is expected that the width of the capture zone will be narrower and similar to GWM70 because it will be drawing groundwater down to the base of the Blasensandstein aquifer (i. e., extracting groundwater from a greater thickness of the aquifer than it is currently).

With GWM37 replaced as a fully penetrating well, the use of GWM37 and GWM70 as extraction wells:

is expected to provide sufficient overlap between the two capture zones and that the most impacted groundwater in the plume will be extracted for treatment, will ensure that a control plane is formed perpendicular to the estimated groundwater flow direction and, therefore, will provide the most efficient method for long-term hydraulic containment of the plume, will create a ‘stagnation zone’ downgradient of the control plane where groundwater velocities will be significantly reduced (i. e., after equilibrium conditions are reached during the extraction works), will slowly remove PFAS mass from the plume area and result in slowly decreasing PFAS concentrations at wells located downgradient of the control plane (i. e., GWM85A, GWM40, and other well; refer to Figure A-7), and the plume will be controlled at the control plane and PFAS concentrations further downgradient

(i. e., offsite) will slowly reduce through dilution only and with a significant time delay.

With establishment of the two overlapping capture zones along the control plane, additional pumping from other wells located within the plume area is not required because it would reduce the groundwater volumes extracted from GWM37 and GWM70, and also reduce the width of the two capture zones (i. e., interfering with the maximum extent of the capture zones).

3.5 Groundwater Column Tests

AECOM conducted a groundwater pilot trial (onsite column tests, /13/) which tested three different, commercially available adsorption media (granular activated carbon (GAC) PFTSorb®, Fluoro-Sorb®, and IX resin Purolite® PFA694E). The groundwater used for the trial was extracted from GWM70 which is located in the middle of the PFAS plume and considered to be representative of groundwater conditions in the middle of the PFAS plume (refer to Section 3.1). The objectives of the pilot trial were to:

undertake an onsite trial of three different adsorbents to assess their ability to reduce PFAS concentrations in the Site’s groundwater, collect sufficient data to allow an assessment of the best adsorbent(s) to be adopted for the full-scale remediation works including considerations of performance, cost, ability to reuse/reactivate the material, disposal costs, and calculation of breakthrough capacity curves and Empty Bed Contact Times (EBCT, time spent by the contaminated water in contact with a treatment medium), etc., conclude which best adsorbent(s) are recommended for full-scale implementation, and provide sufficient information to assist with development of this RD.

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The pilot trial ran from 11 October to 8 December 2022 (58 days) and indicated that:

• The (REDACTED) consistently removed significantly greater PFAS mass than the other two media for the duration of the trial. Importantly, it was also significantly more efficient in removing the two (more challenging) short chain compounds PFBA (Perfluorobutanoic acid) and Perfluoropetanoic acid (PFPeA),

• In terms of performance and cost-effectiveness, the (REDACTED) was considered to be the preferred option for full-scale treatment of the Site’s groundwater. Because it would require less changeouts of vessels per year (compared to (REDACTED) ) it would also bring other benefits including less traffic movements/carbon emissions, less wear and tear on the vessels during changeouts and a reduced risk of safety incidents,

• Lead / lag (polishing) filters would be recommended in order to achieve the discharge criteria and optimize saturation of the adsorbent, and to ensure it is used in an efficient and cost-effective manner, and

• With the regulation of air emissions from thermal treatment works likely to come under greater scrutiny (i. e., from the incineration of PFAS impacted adsorbents), the potential use of a regenerable resin at the Site should be assessed further in the future. This approach, in combination with a potential destruction technology such as the (REDACTED), can provide a solution which requires no offsite treatment or disposal of PFAS wastes.

The pilot trial report (/13/) is provided in Appendix B. The report also (REDACTED) cost estimates for the construction of TS3 and it’s operation and maintenance over a 30-year period (for the three trialed adsorbents).

Based on the findings in the pilot trial report (/13/, including the cost estimates), AECOM recommends the use of the (REDACTED) or another similar performing resin for the treatment of the Site’s groundwater.

4. Preliminaries

4.1 Proposed Clean-up Goals

The proposed clean-up goals for PFAS for TS3 are derived from the relevant preliminary Bavarian guideline (/28/). Accordingly, PFAS-impacted water requires state of the art technology treatment prior to discharge into a surface water body. In case of a groundwater treatment system this requirement is regarded to be fulfilled when the degree of purification for PFAS is at least 90 % (/28/). In addition, compliance with the following discharge criteria are proposed to a) prevent any deterioration as stipulated in § 27 of the “Wasserhaushaltsgesetz” (WHG) (/20/) and b) provide a feasible and technically proportional approach for the Site:

PFOS: 0.02 µg/L, and

PFAS (13 constituents according to /28/): 0.2 µg/L.

Potential co-contaminants such as TPH C10-C40 (H53), CHC, PAH, and AHC were either very low or not detected in the groundwater samples collected from GWM37 and GWM70 (refer to Section 3.1 and 3.2). Therefore, no clean-up goals are necessary for these parameters.

4.2 Permits and Approvals

4.2.1 Permit according to Water Law

An application under water law in accordance with the Water Resources Act („Wassserhaushaltsgesetzt, WHG; /20/“) and the Bavarian Water Act („Bayerisches Wassergesetz, BayWG“; /21/) for the extraction, treatment, and discharge of groundwater must be submitted for

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approval to the responsible environmental office (“Umweltamt”) of the city of Ansbach. This can be done informally (e. g. by e-mail) via the HN Federal Real Estate Agency (“Bundesanstalt für Immobilienaufgaben, BImA“) as the representative of the property owner.

4.2.2 Digging Permit (Utility Clearance)

A digging permit needs to be obtained from the USAG Ansbach, DPW O&M prior to conducting any intrusive fieldwork activities (drilling, trenching, shaft excavation, etc.). Relevant actual utility maps for power, telecommunication, fuel & gas, optical fibers, water, sewer, heating, empty conduits etc. will be obtained from the Garrison, and/or relevant commercial providers for all relevant areas. Commercial providers are for example:

Table 2. Contact Details for Commercial Utility Providers

Utility Contact Details

Deutsche Telekom Technik GmbH (telecommunication)

Technik Niederlassung Süd PTI 13 Nürnberg Am Fernmeldeturm 2 90441 Nürnberg email: Planauskunft.Sued@telekom.de www.telekom.de

N-ERGIE Netz GmbH (gas)

Sandreuthstraße 21 90441 Nürnberg email: Instruktionsfragen@n-ergie.netz.de www.n-www.ergie-netz.de

Stadtwerke Ansbach (cables, gas, water, district heat, etc.)

Rügländer Str. 1 91522 Anbach email: info@stwan.de www.stwan.de as of December 2022

4.2.3 Photo Permit

A temporary photo permission must be obtained through the USAG Ansbach DPW EMD. No military sensitive facilities or equipment may be photographed.

4.3 UXO Avoidance

Appropriate unexploded ordnance (UXO) measures need to be conducted prior to any intrusive activities (drilling, trenching, shaft excavation, etc.). UXO avoidance measures may include magnetometer, electromagnetic, or georadar measurements for shallow intrusions. Down-the-hole measurements will be deployed for deeper intrusions such as the installation of wells. UXO avoidance services need to be conducted by a certified expert in accordance with the Explosives Act (Sprengstoffgesetz / SprengG; /22/).

4.4 Site Access

4.4.1 Access to the Installation

The installation is accessible via the Access Control Point (ACP) / Main Gate of the Katterbach Kaserne.

In general, access will only be granted from Monday to Friday between 0700 and 1800. On American and German holidays, work at the installation may not be possible. Regular working hours at the installation are 0800 through 1700. Waiting time due to personal and vehicle checks or registration formalities at the main gate may be possible.

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For access, at least the first and last name, date of birth, and ID number must be provided in advance.

In order to obtain the access (ID card or access roster), it may also be necessary to submit a current police clearance certificate („polizeiliches Führungszeugnis“). Furthermore, it may be necessary to provide vehicle data such as type of car, license plate number, color, etc.

Access onto the airfield area for the installation of new perched wells and installation of the water extraction and transfer system will need to be discussed and coordinated with USAG Ansbach DPW.

4.4.2 Access to the Treatment Area

The Treatment Area will be located within the fenced area at the rainwater retention basins (Regenrückhaltebecken, RRB) 03 and 04 in the west of the installation (refer to Section 5.7, Figure A- 2 and Photos 1 and 2 in Appendix C). The area is accessible via the ring road.

In general, the gate of the fence is closed. Access will be granted via USAG Ansbach DPW (O&M, Mr.

Frank Otterbein (O&M), phone: 09802 83 2142 or Mr. Stephan Haas (EMD), phone: 09802 83 2225).

4.5 Staging / Stockpiling Areas

Areas available for temporary staging and stockpiling works during the construction phase will need to be coordinated with and approved by USAG Ansbach Masterplanning. The areas are likely to include:

within the fenced site at the Treatment Area, between RRBs 03 and 04, are available for staging and stockpiling (refer to Figure A-5 in the appendix and Photos 1 and 2 in Appendix C), and in the area near GWM70 or the paved car park area located south of GWM37 (west of the internal ring road).

Any temporary staging areas will need to be secured with construction fencing and environmental control measures will be set up around each area as required by the Erosion and Dust Control Plan (refer to Section 1.5).

Machines, equipment, materials, vehicles, fuels, etc. that will be utilized during the excavation and construction work can be stockpiled or set up in these areas. This may also include temporary sanitary facilities.

All materials and machinery or equipment containing operating materials hazardous to water must be secured in accordance with the WHG (/20/) (e. g., placed in a suitable secondary containment) to effectively prevent any release to the subsurface and environment.

USAG AN DPW will assign a hydrant for drinking water supply. The costs for the drinking water are borne by the site. The transport and/or supply to the work area is the responsibility of the company carrying out the work. If the construction contractor requires a connection to the fire hydrant, they will provide and install a backflow prevention device.

A sufficient power supply for the execution of the work cannot be guaranteed at the site. Therefore, a sufficiently dimensioned power supply (e. g. generator) must be provided by the company carrying out the work.

Prior to field work actual potential limitations need to be confirmed with DPW O&M representative (see above). Operation, access, and maintenance of the two RRBs near the Treatment Area must be possible at all times for the duration of the work. The contractor may make alterations to the proposed logistical details after agreement with the DPW.

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4.6 Health & Safety Precautionary Measures

The work partly includes working in potentially contaminated areas (i. e., PFAS impacted soils and perched water / groundwater in the CCAN104 area). Accordingly, the requirements of DGUV Guideline 101-004 (/23/), TRGS 524 (/24/), and also the specifications of the US Army Corps of Engineers Manual EM 385-1-1 (/25/) must be observed. Before the start of the construction work, a site- and project-specific Health & Safety Plan according to DGUV 101-004 (/23/), TRGS 524 (/24/), and EM 385-1-1 (/25/) must be prepared which must be supplemented by a corresponding risk assessment.

Relevant workers employed on the construction site must provide evidence of the relevant occupational medical check-ups. The start and completion of the construction work must be reported in accordance with the regulations of the employers' liability insurance association.

The personal protective equipment (PPE) of each worker and visitor on the construction site will include at least: construction helmet according to DIN EN 397, steel-toed shoes with puncture-resistant sole, and high-visibility vest. Depending on the activity (e. g., in case of possible contact with PFAS-impacted water) and in accordance with the Health & Safety Plan, the PPE must be supplemented with appropriate disposable protective suits, gloves (e. g., for protection from cuts and/or chemicals), hearing protection (e. g., when the noise level is >80 dB), safety goggles, etc.

At least one first aid kit, one fire extinguisher, and one mobile phone, a list of emergency numbers, and a copy of the “Red Plan” must be kept on site for the duration of the construction work.

If necessary, the construction site or individual construction measures are to be secured against entry by unauthorized persons (refer to Section 4.4) and appropriate warning signs are to be affixed. For the trenching works along the internal ring road, barriers are to be provided in accordance with the road traffic regulations or in consultation with the Military Police (MP) of the USAG AN. This may include barriers (warning beacons, pylons, etc.), warning lights (at night), temporary speed limits, etc.

Appropriate barriers and safety measures must also be provided when working near open trenches,

e. g., for power, control, and water lines, or manholes.

4.7 Ambient Air Monitoring in the Working Area

Due to the known spectrum of pollutants (refer to Section 3.1), no monitoring measures of the ambient air are required. I. e., PFAS is not a volatile chemical which requires ambient air monitoring.

If dust is observed during excavation work and dry weather conditions, appropriate measures (e. g.

wetting down of surfaces) must be taken to effectively prevent dust development as required by the Erosion and Dust Control Plan which will be prepared (refer to Section 1.5).

4.8 Management of Waste (IDW)

All waste generated is to be collected, temporarily stored, treated and disposed of in accordance with the USAG AN Environmental Management System (EMS) and the required Waste Management Plan (refer to Section 1.5). Waste generated during the course of the work at the site will likely include residual soil, used personal protective equipment (gloves, protective suits, etc.), and empty packaging of construction and other materials. This waste will be separated and temporarily stored in closed containers in the staging area for proper disposal or recycling at certified waste facilities.

Surplus soil material that is not to be backfilled (e. g., from the trenches) must be representatively sampled by certified field sampling personnel IAW German guideline PN98, analyzed according to the German LAGA M 20 (1997) waste disposal guideline (/26/)1, the German landfill ordinance (DepV), the Bavarian PFAS guideline (version July 2022 (/28/)), disposal and reuse categories determined accordingly, and sent for appropriate external disposal and/or reuse.

1 Note that from August 1, 2023, the „Mantelverordnung“ (/27/) incl. „Ersatzbaustoffverordnung“ will be effective in Germany.

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The excavated soil material will be separated, stored on a sealed surface (e. g., on a tarp) and covered during the above temporary storage and testing works.

The option for the soil to be treated during the potential CCAN104 soil remediation project will also be confirmed.

Should surface water be encountered and extracted during the excavation work - in particular during the construction of the new shafts - this must be collected and treated in an appropriately dimensioned mobile treatment plant. This treated water will be discharged into the wastewater sewer or storm water sewer (via the discharge line and shaft 105009A to the Katterbach creek) after approval by the responsible USAG AN DPW O&M department and the HN authority.

5. Remedial Design In preparing this Remedial Design, some in-built flexibility has been included so that the bidding remediation contractor can use their own project experience to propose the most efficient and innovative methods / technologies to achieve the project requirements.

5.1 Proposed Remediation Technology

Based on the most recent groundwater monitoring round conducted in June 2022 (completed as part of the Groundwater Investigation (refer to /12/), maximum total PFAS concentrations were reported in the middle and downgradient portion of the plume (likely groundwater extraction area) at GWM01-Off and GWM70 (52.5 and 59.2 µg/L, respectively). The results obtained from the emissions sampling conducted during the longer-term pumping tests (refer to Section 3.1) indicate that total PFAS concentrations in the extracted groundwater are likely to range between approximatelly 20 and 45 µg/L.

After the additional drilling and installation of monitoring wells during the Groundwater Investigation (/12/), the PFAS groundwater plume is considered to be appropriately delineated at the Site.

In accordance with the recommendations of the DD (refer to Section 1.4), groundwater extraction works are proposed at the Site to provide appropriate hydraulic control of the plume and to enable treatment of the impacted groundwater. This will include extraction from both the highly impacted perched water and the groundwater.

Based on the pumping tests conducted and specifically the capture zones which have been estimated for GWM37 and GWM70, it is considered that groundwater extraction from GWM37 and GWM70 will be sufficient to appropriately capture groundwater within the main plume (refer to Section 3.3, Appendix A, and Figure A-7). It is proposed to pump this water via a new underground service line to TS3 located at the Treatment Area (refer to Figures A-1 to A-4).

As discussed in Section 3.5, based on the findings of the pilot trial report (/13/, refer to Appendix B), AECOM recommends the use of the Purolite® PFA694E resin or another similar performing resin for the treatment of the Site’s groundwater. Further details on the TS3 design are provided in Section 5.8.

To the extent practicable, PFAS concentrations in the TS3 treated water will be reduced to meet the proposed clean-up goals (refer to Section 4.1) so that it can be discharged to the surface water Katterbach Creek in compliance with the relevant discharge permit (refer to Section 1.5).

The /12/ investigation concluded that because similar total PFAS concentrations were reported in the A- and B-aquifers in the downgradient area of the plume, “fully penetrating wells should be used for any hydraulic control / remediation works at the Site”. Consequently, GWM37 will need to be over-drilled and installed deeper to the base of the Blasensandstein unit (i. e., replaced as a fully penetrating well).

The current depth of this well is 17.1 m below ground level (bgl). Depending on field observations during the drilling works, the well will be installed up to a depth of 30 m bgl.

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While extraction of groundwater from GWM37 and GWM70 will control the PFAS plume, additional water extraction works will also be conducted from GWM78A (shallow groundwater) and the perched water (refer to Section 5.3.2 and Figure A-6). While the volume of groundwater extracted from these wells will be smaller, and therefore not adversely interfere with the above discussed capture zones, removal of this highly impacted water from shallow depth will benefit the project in the long term. These extraction works are discussed further in Section 5.3.2.

5.2 Benefits of the TS3 Location at the Treatment Area

For the treatment of extracted groundwater from the Site, the location of TS3 at the Treatment Area offers the following potential benefits:

The preference to avoid building additional structures and generating additional traffic movements to and from the Site during construction and operation (i. e., within the fenced active airfield and security zone), Use of the same water discharge shaft and discharge point, and power supply conduit pipe as TS2 which will also be located at the Treatment Area (refer to Figure A-5), The possibility in the future to combine the TS3 treatment, operation and maintenance (O&M) tasks with the TS2 works. Combined tasks for the two projects could potentially include:

─ A combined treatment system, ─ Absorbent backwashing and changeouts, ─ O&M site visits, ─ validation sampling works, ─ laboratory analysis, and

─ validation reporting.

Potential streamlined DPW and HN management of both projects in the future (i. e., combined project meetings, review of less reports, etc.).

The above benefits have the potential to provide a more cost-effective approach to both projects which will likely operate over the long term (i. e., longer than 30 years).

5.3 Water Extraction Area

5.3.1 Groundwater

As discussed in Section 3.3 and 3.4, the data obtained from the combined GWM37 and GWM70 pumping tests have enabled the estimation of the likely required capture zones from the proposed groundwater extraction works (refer to Figure A-7). The estimated combined capture zones from the proposed GWM37 and GWM70 extraction wells (both operating as fully penetrating wells) is considered to be appropriate for the long-term hydraulic control and remediation of the identified PFAS plume.

GWM37 will require conversion to a fully penetrating well to the base of the Blasensandstein unit to a depth not greater than 30 m (dependent on field observations during the drilling works). It is noted that a new 50mm monitoring well (to be named GWM92A) which will also be installed in the car park area between GWM37 and GWM79A (refer to Figure A-17). These additional drilling works will be conducted in accordance with the PFAS Site Characterization Plan (/10/).

In addition, because of the very high PFAS concentrations reported at GWM78A (refer to Section 3.1), the shallow groundwater from this well will also be extracted for treatment at TS3. The recharge of this well during the pumping tests (/12/) indicated low flows in the order of 1L/min. However, given the reported high PFAS concentrations, extraction of the water is considered to be warranted. Water from this well will be pumped to the GWM70 area before transfer to TS3 (refer to Figure A-6).

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5.3.2 Perched Water

As discussed in Section 3.1 and shown in Figure A-8 (2015 and 2021 results), very high PFAS concentrations have been reported in the perched water close to the former FFTP (i. e., to the west and north west of this structure).