PWS Enclosure 2C - SITE ADDED CONSIDERATIONS SUMMARIES.docx

Enclosure 2C:

Site added considerationS summarIES

This summary of site-specific considerations is a result of internal AF discussion and analysis completed while formulating the performance objective (PO) and is provided as Government Furnished Information (GFI). As with all GFI, it is for informational purposes only; the Contractor remains responsible for developing their own independent, professional conclusions/ interpretation of site conditions and requirements to achieve the PO.

The Performance Work Statement (PWS) requires project scoping sessions before work plan development and throughout the planning and execution of the project to meet the PO. The AF review team has identified the following initial items to be considered in project scoping.

JBC-Air SITE dd540 (aoc p) The PO for this site is to Conduct RA-O with Optimization

Background - The current remediation system in place at the site was selected after an initial plan of chemical injection was disapproved by Airfield Management and Base Engineering. The system has successfully reduced concentrations in portions of the groundwater plume, but it appears to be unable to impact portions of the contaminant plume that are outside its radius of influence. Optimization of the system or consideration of alternative remedial options are necessary.

The following information reflects discussions with the Airfield Management and Base Engineering regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record.

· Both Airfield Management and Base Engineers will have to approve any intrusive remediation plans for the site due to its location in the airfield. Previous submittals of remedial plans involving injection were not approved because they were deemed as compromising the strength of the concrete pavement.

· Both entities have stated they could approve injection points so long as they are spaced sufficiently as to not compromise the concrete pavement. Specifically, injection point locations should be installed outside the path of plane tires as well as utilizing contraction lines in the pavement.

· All work done in this area will require appropriate permitting associated with doing work on the airfield through both the base and the FAA.

JBC-Air SITE FT003 (SWMU 55) The PO for this site is to Conduct RA-O/LTM and Reduce LCCs

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

· Site is the former fire training area. Releases of petroleum and chlorinated solvents occurred due to fire training activities at the site. AFFF was also utilized at the site resulting in PFOA/PFAS impacts to the soil, groundwater and surface water. A robust treatment system is planned for the site as part of the PFAS CERCLA Action. This treatment system will also treat impacts to chlorinated solvent groundwater plume.

· The regulator understands remediation efforts for the PFAS CERCLA Action will also remediate the remaining RCRA COCs at the site.

· Documentation of the new treatment and its impact on the RCRA site maybe required before the remedial system can be approved. This documentation may include a CMS Addendum, a CMI Workplan, and a Statement of Basis.

JBC-Air SITE OT012 (SWMU 58) The PO for this site is to Conduct LTM

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

· Regulator requests delineation of strontium and molybdenum due to change in groundwater flow with construction of stormwater drainage ditch. Placement of monitoring wells will be restricted by the Clear Zone boundary around the runway as well as the wetlands that surround the site.

JBC-Air SITE OT016 (SWMU 137) “zone 2” The PO for this site is to Achieve Response Complete.

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

· Regulator requests delineation of the pesticide groundwater plume identified at monitoring well Z2-01.

· As noted for Zone 4, regulator requests a data gap investigation to determine if the vinyl chloride detected in monitoring well Z2-45 is associated with the vinyl chloride groundwater plume from Zone 4.

· Plans have been proposed by the Base for the demolition of the current entomology building located adjacent to monitoring wells Z2-02 and Z2-137-02. When the building is demolished a soil and groundwater assessment of this area for pesticides will be necessary.

· Regulator will consider eliminating the long-term monitoring for Zone 2 if the following conditions are met:

· Vinyl chloride plume is demonstrated to be associated with Zone 4.

· Successful remediation of the chlorinated solvent plume at monitoring well Z2-46.

· Successful remediation of the dieldrin plume on the northeastern edge of Zone 2.

JBC-Air SITE SS042 (SWMU 149) “Zone 4” The PO for this site is to Conduct RA-O and Achieve Alternate Objectives

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

· The primary issue(s) at this site which need further discussion and information are related to the likely presence of a DNAPL source in one area, and performance of the remedies implemented (specifically the generation of vinyl chloride as part of the enhanced reductive dechlorination (ERD) treatment process).

· Zone 4 is comprised of several chlorinated solvent plumes from numerous sources. Previous remedial activities include EVO injection into the groundwater plume and soil vapor extraction for treatment of a soil source area. Vapor intrusion mitigation utilizing sub-slab depressurization systems are in use. DNAPL is observed in one of the source areas.

· Although EVO injection into the groundwater plume has greatly reduced the groundwater plumes, a vinyl chloride groundwater plume appears to be increasing as a breakdown product. The regulator would like consideration of using a zero valent iron product such as used at the nearby Zone 2 chlorinated solvent groundwater plume where the successful treatment method resulted in minimal production of vinyl chloride.

· Vinyl chloride has been detected in monitoring wells along the southeast edge of Zone 2. Numerous utilities are located between the two zones that may be acting as a preferential pathway for the shallow groundwater plume. A data gap investigation is needed to assess and delineate the vinyl chloride plume that appears to extend from the northern edge of Zone 4 into Zone 2. If the vinyl chloride detected in Zone 2 is confirmed to be resulting from the Zone 4 plume, then the conceptual site model for both zones will need to be updated.

· The oil water separator located at the source area adjacent to Building 543 (identified as SWMU 151) appears to be a significant source of DNAPL. A data gap investigation is expected to assess COC concentrations in soil around the oil water separator. Based on the results of the soil data gap investigation, the soil vapor extraction system should be modified to remediate this area. Confirmation soil samples from current area of treatment at the SWMUs 88, 90, 104, and 122.

· The regulator and AFCEC agree the DNAPL in the SWMU 151 source area should be successfully treated to dissolved phase concentrations by the end of the ORC contract.

· Annual progress reports provide an assessment of the ERD remedial system and the O&M of remediations systems located at Bldg 532 and Bldg 543.

JBC-Air SITE ST027 (SWMU 145) The PO for this site is to Achieve Site Closeout

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

· Monitoring well MW20-24 is located in a low spot adjacent to a stormwater drop inlet. The well was recently repaired because surface runoff was infiltrating the well which is believed to be the source of the naphthalene. The monitoring well may need to be replaced.

· Another possible source may be upgradient of monitoring well MW20-08R. A groundwater investigation upgradient of the well may be necessary if naphthalene concentrations persist.

JBC-Air SITE TS837 (AOC X) The PO for this site is to Achieve Response Complete

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

The site is currently in Tier 2 dispute resolution about the proposed remedy options provided in the Feasibility Study. Possible outcomes include:

· Removal of surface soil from Decision Units 22, 27, 28, 29, 33, and 34. This remedy would require an update to Feasibility Study, a Statement of Basis, and a CMI Workplan as well as Construction Completion Report.

· Implementation of land use controls. An updated Feasibility Study may be necessary for this remedy.

JBC-Air SITE TU542 (AOC V) Shoppette The PO for this site is to Achieve Site Closeout.

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

· Site received SCDHEC USTP Conditional No Further Action (CNFA) on April 12, 2019, because current well network sampling analyses obtained less than Site Specific Target Levels (SSTLs) for CoCs (BTEX/Naphthalene). Air Force Response Complete (RC) was obtained in June 2019. Site Closure (SC) has not been recommended/approved because CoCs are still at concentrations greater than MCLs/RBSLs since the gas station infrastructure had limited remediation of the contaminant plume using the former Air Sparge/Soil Vapor Extraction system. The remedial system has been decommissioned and removed from the site.

· In June 2020, a spill bucket failure was identified at a premium fuel UST. A direct push temporary well was installed directly downgradient of the spill bucket and one groundwater sample was collected to be analyzed for BTEX and naphthalene. Analysis of the groundwater sample indicated that all constituents, except for xylenes (total), were above their respective RBSL/MCL. A second incident was created for the site as a result of the spill. A summary of the results has been provided in the table below.

As a result of the new incident, the regulator is requesting annual groundwater monitoring of 7 monitoring wells for BTEX, Naphthalene, and MTBE. One well also analyzed for EDB and oxygenates (assume oxygenates analysis is covered under testing for other parameters).

· Replacement monitoring well MW-5R has previously be misidentified as downgradient of MW-5, which historically has contained LNAPL. MW-5R is actually located cross-gradient from MW-5 and may not reflect the presence of LNAPL at the site. Regulator has requested a Laser Induced Florescence (LIF) study around former MW-5 to determine free product is still at the site.

· Assessment of the new release is necessary to determine nature and extent of contamination in soil and groundwater caused by the underground storage tank spill bucket failure.

· Regulator expects a corrective action to address both incidents as they are most likely co-mingled. Regulator would like consideration of an oxidant injection or a combination of surfactant injection with AFVR as remedial options for the site.

JBC-air SITE tu543 (SWMU 108) The PO for this site is to Achieve Site Closeout.

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

· Regulator requests a delineation of the LNAPL using Laser Induced Florescence (LIF) technology

· Currently there is no SCDHEC approved CMS or SoB for corrective action at the site. The regulator requested a CMS and SoB for a more aggressive remedy such as surfactant injection with AFVR.

· Regulator will grant NFA when no measurable LNAPL (<0.01 foot) is observed and naphthalene concentrations are less than the RBSL (25 µg/L) for 3 years of annual groundwater monitoring.

JBC-WeAPONS SITE DA017 (SWMU 17)

The PO for this site is to Conduct RA-O and Achieve Alternate Objectives.

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

1. Although EVO injection into the groundwater plume has greatly reduced the groundwater plumes, a vinyl chloride groundwater plume appears to be increasing as a breakdown product. The regulator would like consideration of using an injection product with more zero valent iron composition.

The following information summarizes an injection pilot studies that have yet to be documented in any reports to date.

Injection activities completed on 6/9/2020 at SWMU 17 included the following:

· Injections of a ZVI mixture (ZVI and water) at 17IW14

· Injections of EVO at 17IW08 and 17IW09

· Injections of water at 17IW14 and 17IUW17 Daylighting occurred during injections at each of the aforementioned locations. Based on the consistent daylighting that occurred regardless of the material being injected, the conclusion is that the formation is clogged or simply limited in the quantity of injectant that it can accommodate.

Similar issues were identified at one of the pilot test injection wells (17IW01) during subsequent site wide injections in 2018. The reoccurrence of these issues during this injection event may indicate potential issues with reuse of the dedicated injection wells that would need to be reexamined prior to future injections at SWMU 17.

Volume Injected (6/8/22): Total of 1380 gallons injected at the following six injection wells

· 17IW08: 358 gallons

· 17IW09: 300 gallons

· 17IW10: 169 gallons

· 17IW12: 184 gallons

· 17IW14: 188 gallons

· 17IW17: 181 gallons Mixed injectant remains at the site from injection activities attempted on 6/8/2022 and 6/9/2022. Current contractor intends to inject these materials over the course of the day (6/10/2022). These materials will be injected at low flow rates and pressures to minimize daylighting as much as possible. The purpose of the injections on 6/10/2022 is to minimize the quantity of material that needs to be disposed of as waste from the site. After all mixed materials have been injected, we would like to terminate the injection activities at the site. The activities completed and the issues identified will be discussed in the subsequent report. The CCR activities will be documented in the next CMI progress report for SWMU 17.

JBC-WeAPONS SITE FL066 (SWMU 66)

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

· Regulator requests a data gap investigation of the source area with an updated CMS to address remediation of the source.

JBC-WeAPONS SITE SA036 (SWMU 36)

The PO for this site is to Achieve Response Complete

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

· In 2019, a concrete debris pile was identified in the north central area of SWMU 36 that was not included in the remedy in the CMS report. The regulator requests proper disposal of the concrete debris.

· Regulator and AFCEC agree additional rounds of injection should be conducted to continue reducing the chlorinate solvent groundwater plume.

JBC-WeAPONS SITE ST042 (AOC G)

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

· Regulator requests a re-evaluation of the site boundary with potential installation of groundwater monitoring wells. The CMS should be updated if appropriate.

JBC-WeAPONS SITE TU927 (AOC B-2)

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

Background - The site contained a 10,000-gal UST and associated piping and was used to supply fuel oil to residential boilers for heating purposes. The tank and piping were removed in 1995 along with 6,950 gal of wastewater contaminated with free product. Two soil excavations occurred at this site (2000 and 2002). Groundwater historically contained naphthalene in excess of screening levels. LNAPL was historically detected historically in 3 monitoring wells. Vacuum extraction events, bailing and passive recovery techniques were used as needed to remove LNAPL. Soil profiles are typically comprised of medium to silty sand from land surface to 30 ft bgs. GW is generally encountered from 3 to 13 ft bgs. GW flow is generally to the southeast at TU927.

Remediation Completed to Under JBC PBR - Contaminated soil was excavated from the site in August 2018. 1,721 tons of soil was disposed of along with 3,000 gallons of storm water from the excavation due to hurricane Florence. ORC-A was injected into 26 DPT locations on 1 Nov 2018. 1,500 pounds of ORC-A mixed with water creating 1,200 gallons of slurry. Each point received approximately 46 gallons of slurry. Injection points were spaced on a 7.5 foot radius of influence. Injected at 3.4 to 5.7 gallons per minute at 200-300 psi.

Performance sampling indicates naphthalene in MW-3B remains at concentrations exceeding screening levels. This monitoring well was redeveloped in January 2021 to ensure adequate connection with the aquifer at MW3B. Sampling completed after the redevelopment resulted in similar naphthalene concentrations.

Remediation to be Completed in 2022 - Based on the results of the ORC-A injections at B-2, this remedial method was not successful at reducing contaminant concentrations below screening levels. BOS-200@ will be the remedial method utilized to address the remaining contaminant concentrations at B-2.

Contamination at B-2 is limited to naphthalene in MW-3B. Based on the limited extent of contamination identified, a targeted injection area is shown (highlighted in red shaded rectangles) in the figure below. As presented in the Corrective Action Plan Addendum located in the Administrative Record, a supplemental injection was conducted in June 2022 using BOS-200 to address the naphthalene contamination remaining at the site in excess of screening levels. 16 pre-determined injection Direct Push Technology locations surrounding MW1025F-3B were used to inject 990 gallons of BOS-200. Groundwater monitoring was conducted in August and October of 2022. Naphthalene did not exceed the RBSL during these two performance monitoring events.

JBC-WeAPONS SITE TU939 (AOC B-3)

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

Background - The site is the location of the former Heat Plant, demolished in 2004. The building contained a boiler and an associated 4,000-gal steel UST that contained diesel fuel. The UST was installed in the 1960s and closed by excavation in 1988. Subsequent soil and GW sampling indicated the presence of petroleum COCs in excess of the MSCs for soil and GW. In addition, benzo(a)pyrene (99.7 µg/kg) exceeded the EPA residential RSL for dermal contact at one location. LNAPL detections were historically reported in three site wells. Soil profiles are typically comprised of medium to silty sand from land surface to 30 ft bgs. GW is generally encountered from 3 to 13 ft bgs. GW flow is generally to the east at TU939.

Remediation Completed to Under JBC PBR - Contaminated soil was excavated from the site in October 2018. 224 tons of soil was disposed of along with 2,700 gallons of storm water from the excavation due to hurricane Florence. ORC-A injected into 16 DPT locations end of October 2018. 62.5 pounds of ORC-A mixed with water creating 50 gallons of slurry which was injected into each location. Injected at 1.2 to 4.6 gallons per minute at 150-300 psi.

Performance sampling indicates naphthalene and benzene in MW-1 remains at concentrations exceeding screening levels. Performance sampling indicates naphthalene in MW-2R remains at concentrations exceeding screening levels. These monitoring wells were redeveloped in January 2021 to ensure adequate connection with the aquifer at MW 1 and MW-2R. Sampling completed after the redevelopment resulted in similar naphthalene and benzene concentrations.

Remediation to be Completed in 2022 - Based on the results of the ORC-A injections at B-3, this remedial method was not successful at reducing contaminant concentrations below screening levels. BOS-200@ will be the remedial method utilized to address the remaining contaminant concentrations at B-3.

Contamination at B-3 is limited to naphthalene in MW-1 and MW-2R and benzene in MW-1. Based on the limited extent of contamination identified, a targeted injection area is shown (highlighted in red shaded rectangles) in the figure below. As presented in the Corrective Action Plan Addendum located in the Administrative Record, a supplemental injection was conducted in June 2022 using BOS-200 to address the naphthalene contamination remaining at the site in excess of screening levels. 10 pre-determined injection Direct Push Technology to inject 771 gallons of BOS-200. Daylighting of injection slurry was observed at IP-9, IP-4, IP-8, and IP-2, most likely due to preferential pathways created by previous injections, utilities, and excavations in the small footprint of the site. Groundwater monitoring was conducted in August and October of 2022. Naphthalene did not exceed the RBSL during these two performance monitoring events. Benzene was not detected above the RBSL at any monitoring wells during the August 2022 sampling event. Benzene was detected above the RBSL at MW-1 (6.5 ug/L) during the October 2022 monitoring event.

NAAF SITES DA100 and TA001

The PO for these sites is to Achieve RC

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

1. NAAF is an auxiliary airfield utilized for training by several DoD groups. Due to the nature of its operations, NAAF produces minimal hazardous waste and is not regulated under a RCRA Permit.

2. A 1983 Phase I Record Search identified 4 landfills and a POL Storage Tank Area at NAAF. SCDHEC (state regulator) requested that these sites be environmentally investigated.

3. A Site Investigation is being conducted as a CERCLA action. Each site will be identified as the following:

· Landfill 1 (aka Surface Debris Area 1) – DA100-1

· Landfill 2 (aka Surface Debris Area 2) – DA100-2

· Landfill 3 (aka Surface Debris Area 3) – DA100-3

· Landfill 4 (aka Surface Debris Area 4) – DA100-4

· POL Tank Storage Area– TA001

4. The 1983 Phase I Record Search identified the surface disposal areas as Landfills #1 through 4 which is reflected in the PA and SI QAPP. The names of the sites were changed for the SI Report after field activities for the SI indicated the areas may be misidentified as landfills and appear to be surface disposal areas. Initial conversations with the regulator resulted in the change of the sites’ names, but recent comments from the regulator suggest the names cannot be changed until the SI Addendum is completed presenting strong evidence that the sites are not landfills (i.e., no buried debris).

5. The regulator has further elaborated to AFCEC in a telephone conversation on their comments provided in their 12 September 2022, comments letter. The regulator expects an SI Addendum to clearly demonstrate evidence that landfilling activities did not occur at the sites before they will concur that the sites are surface debris areas. They have requested information generated from the following tasks be included in the SI Addendum:

a. Conduct ground penetrating radar and a magnetometer survey of the four (4) Surface Debris Areas to identify both surface and subsurface debris.

b. Surface debris (metal, asphalt/concrete, rubber, plastic, etc.) shall be mechanically removed for proper disposal with soil and groundwater samples collected and analyzed for VOCs, SVOCs, PAHs, metals, PCBs, and pesticides when potential releases are encountered.

c. Trenching activities (e.g., test pits) at all four surface debris areas to verify no buried waste is present at the sites. The number and location of the test pits are to be determined based on the size of each site to appropriately demonstrate to the regulator if landfilling activities occurred at the sites.

d. Establish site specific background concentrations for metals

e. At the POL Storage Tank Area (Site TA001), conduct a ground penetrating radar survey to verify no buried tanks or associated piping are present.

f. If localized releases are identified from surface debris, then the impacted soil will need to be excavated for proper disposal. Down gradient groundwater monitoring will be needed to demonstrate no groundwater pathway exists.

g. If buried debris is encountered at a site, then the regulator will consider the landfill sites to be “waste left in place” and the site will need further investigation and potential remedial action through the CERCLA process including:

· Delineating the lateral and vertical extents of the buried debris

· Verify cover thickness or constructing a suitable cap if necessary

· Establishing and maintaining land use controls

· Establishing a long-term groundwater monitoring program to include downgradient wells

6. The regulator also expressed concern about potential unexploded ordnance present at Landfills 1 and 3. For safety precautions, a MMRP Comprehensive Site Evaluation Phases I and II will need to be conducted on these sites to develop a sufficient safety plan for the SI Addendum activities.

7. A Construction Material Staging Area consisting of approximately 3 acres of inert material (demolished concrete taxiway chunks, ground up asphalt piles, inert metal debris) generated from runway construction activities is located at NAAF. This area is actively used and not part of the CERCLA action. AFCEC will support base operations with the disposal of the construction debris currently staged at the site. The contractor shall responsible for estimating the type of debris and tonnage during the site walk. The material can be recycled/reused or disposed at an appropriate permitted disposal facility.

Construction Material Staging Area Location: 33°35’45.7’’N, 81°04’25’’W

SJAFB SITE RW502

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

· No Further Restoration Action was requested in September 2015 but was not granted by the NCDEQ. As the Carolina Group PBR had already been awarded in 2013, the RW502 site at SJAFB was added through modification to the existing PBR as an Optimized Exit Strategy (OES) site with a requirement for groundwater monitoring only and no active remedial activities.

· Implement corrective action plan addendum

· Sampling of well network until contaminant levels are below MCLs for a minimum of four (4) consecutive quarterly events following shut down of any corrective action system.

SJAFB SITE SS033

The following information reflects discussions with the regulator regarding the site. This information is not reflected in any reports or decision documents in the Administrative Record:

· Submission of a suitable corrective action addendum and corresponding workplan and approval of both by NCDEQ.

· Implement corrective action plan addendum

· Sampling of well network until contaminant levels are less than MCLs for a minimum of four (4) consecutive quarterly events following shut down of any corrective action system.

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