KEMRON

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Hunters Point Naval Shipyard

The Hunters Point Naval Shipyard (HPNS) Remedial Action for Parcel E2 is a significant environmental remediation project managed by KEMRON Environmental Services, Inc. since 2016. This project involves the comprehensive cleanup and stabilization of a 47.4-acre former landfill along the southwestern shoreline of HPNS in San Francisco, CA. The scope of work includes constructing a multi-layer protective liner system, installing landfill gas extraction wells, and implementing various environmental controls and protections in accordance with the CERCLA remedy and the final Design Basis Report (DBR).

KEMRON began the project by preparing a detailed Remedial Action Work Plan (RAWP), outlining the methods and procedures for the cleanup. This included implementing stringent radiological controls and setting up Best Management Practices (BMPs) and environmental protection measures as specified in the CERCLA Stormwater Plan (SWP). An on-site administrative field office was established, and site access was constructed. Stormwater sampling is conducted as needed to ensure compliance with the SWP.

The initial construction phase required the importation of over 200,000 tons of clean soil, transported via barge from an off-site location. This soil was used to build the foundation layer for the multi-layer landfill cap. KEMRON performed extensive soil characterization, sampling, and analysis to ensure compliance with California state requirements. The clean soil was then placed, graded, and compacted using GPS-controlled dozers to meet precise specifications.

The construction of the multi-layer protective liner system is a critical component of the project. The liner includes a geocomposite clay layer (GCL), High-Density Polyethylene (HDPE) layer, a geocomposite drainage layer, and a demarcation layer. KEMRON’s installation process involves rigorous quality control measures, including survey locations at each liner panel and quality control testing of the HDPE field seams. Liner work is carefully scheduled to avoid moisture conditions that could affect seam quality.

KEMRON installed landfill gas extraction wells through the liner and into the landfill mass, ensuring a gas-tight seal with HDPE boots. These wells are connected to a gas conveyance system with control valves and vaults. Surface water drainage features, including subsurface HDPE piping, are constructed, and the vegetative cover is graded to the design specifications. The cover, compacted to 90% proctor, is seeded with a drought-resistant native mix.

Throughout the excavation and construction phases, radiation control areas (RCAs) are established to monitor and manage any low-level radioactive waste (LLRW) present in the landfill materials. KEMRON’s subcontractor, Perma-Fix, performs radiation monitoring and surveying under their NRC license. Excavated soil is spread in existing radiological screening yards for rad surveying to determine if it can be reused as clean fill or requires further testing.

Upon completing the construction activities and off-site disposal of any LLRW, KEMRON prepares the Remedial Action Completion Report (RACR) and a Post-construction Operations and Maintenance (O&M) Plan. This includes as-built drawings and finalized methods and procedures. O&M inspections are conducted regularly during a one-year post-construction period to address any required corrective actions. Quarterly inspections and annual O&M reports are prepared to monitor landfill gas, stormwater, and wetlands in accordance with the DBR.

KEMRON was tasked with preparing a Field Change Request (FCR-03) to redesign the liner foundation layer after identifying breaches in the existing liner. The revised design included a new grading plan and additional GCL and HDPE layers, ensuring the final remedy was more protective and met all regulatory requirements. Additionally, KEMRON replaced a vibratory roller with a larger non-vibratory roller to address concerns about off-site vibrations while still meeting compaction requirements.

Ex-Situ Thermal Remediation Bench Scale Treatability Study Perfluorinated compounds (PFC)
KEMRON’s Applied Technologies Group performed an ex-situ thermal remediation bench scale treatability study on soil which was impacted with compost impacted with PFCs. Common PFCs include perfluorooctanoic acid (PFOA), used to make fluoropolymers such as Teflon, among other applications; or perfluorooctanesulfonic acid (PFOS), used in the semiconductor industry, 3M’s former Scotchgard formulation, and 3M’s former fire-fighting foam mixture; or perfluorononanoic acid (PFNA), used as surfactant in the emulsion polymerization of fluoropolymers; or perfluorobutanesulfonic acid (PFBS), used as a replacement for PFOS in 3M’s reformulated Scotchgard; or perfluorooctanesulfonyl fluoride (POSF), used to make PFOS-based compounds; or perfluorooctanesulfonamide (PFOSA), formerly used in 3M’s Scotchgard formulation; and FC-75, a 3M Fluorinert liquid; and perfluorinated cyclic ether (PFCE).

The treatability study was performed to determine the treatment temperatures potentially capable for thermal destruction of PFCs in highly organic soil at the site. The site test material consisted of highly organic soil which had been composted at different decomposing time intervals. Four candidate site materials with decomposition times of 3, 6, 12, and 18 months were subjected to thermal treatment performed at three target temperatures and one retention time. The materials in the study were initially heated to 100 Celsius to completely remove all moisture prior to subjecting the material to the target temperatures of 200, 398, and 1,100 degrees Celsius. Treatment durations were approximately 15 minutes at the target treatment temperature. Throughout treatments KEMRON performed constant temperature monitoring of the soil. All vapors were passed through an activated carbon off-gas treatment prior to releasing into the atmosphere.

KEMRON was not provided with the results of PFC analyses conducted on the treated test materials. However, discussions with the client indicated that treatment temperatures in excess of 1,000C showed successful reductions in total PFC concentrations.

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