Fort Buchanan Army Reserves Bayamon, Puerto Rico
Under our Environmental Remediation Multiple Award Contract (ERMA), KEMRON was awarded a performance based project for environmental services at Fort Buchanan in Puerto Rico. The project includes six sites at the installation including the Northwest Boundary Area (NWBA) groundwater TCE plume, Pesticide Burial Trench, Spent Solvent Storage Area (Building 556), Used Oil Storage Area (Building 556), Heavy Equipment Storage Area (Building 556) and an Inactive Waste Disposal Area (Debris Landfill). KEMRON is responsible for corrective measures implementation (CMI) at the NWBA TCE site to include bio-augmentation and enhanced reductive dechlorination, a Vapor Intrusion (VI) Study, and long term management (LTM_ after remedy implementation. KEMRON is responsible for the preparation of the CMS for the remaining five sites. The recommended corrective measure for four of the sites in no action with a LUC applied at the debris landfill.
FTB-034 – Northwest Boundary Area Groundwater Site is a large chlorinated groundwater plume that extends off base into the adjacent Caribbean Petroleum Refinery Corporation property. The TCE groundwater plume is located in the northwestern portion of the installation. In 2010, the down-gradient limit of the plume extended outside the installation boundary and was estimated to be approximately 45.2 acres. The plume consists of chlorinated solvents, including tetrachloroethylene (PCE), TCE, 1,2-dichloroethene (1,2-DCE), and vinyl chloride (VC). The primary contaminants of concern at the site is TCE. KEMRON prepared a Corrective Measures Study and Implementation Plan (CMIP) was to design the groundwater remediation and the LTM of the site to bring the groundwater into compliance with the interim remedial goal of 100 ppb TCE. The CMIP was approved by the EPA and PRDEQ for the groundwater plume containing TCE. The CMIP was designed to bring the groundwater into compliance with applicable cleanup requirements. The CMIP was prepared for EPA and Puerto Rico Environmental Quality Board (PREQB) and included the site history, description, background, environmental setting, nature and extent summary, HHRA and SLERA summary, and the design for implementation of the groundwater remedy. In addition, to the CMIP, KEMRON prepared an APP/SSHP, UFP-QAPP and QCP.
KEMRON expedited a pilot scale treatability study which included the installation in-situ microcosms, some of which were baited with different carbon substrates, other groundwater amendments, and zero valent iron (ZVI), to determine if sufficient Dehalococcoides bacteria species were present and if the bacteria responded to the amendments to form population sizes large enough to fully degrade PCE and TCE. ZVI was also added to select locations. It was determined through pilot testing that bacterial cultures would need to be injected in the groundwater after the substrates, phosphate buffers, etc. normalized the geochemical parameters of the groundwater to support bacterial growth and reductive dechlorination.
Enhanced bioremediation via reductive dechlorination at the NWBA was implemented. To implement enhanced reductive dechlorination at the site with augmentation and stimulation, the dissolved plume exceeding the interim goal of 100 µg/L for TCE was divided into two treatment areas. The sources area was treated using a series of injection wells and the downgradient dissolved groundwater plume was treated using a barrier wall. Following injection of the ABC+® Formula, groundwater conditions at injection/extraction and nearby wells were monitored for water quality parameters including temperature, pH, conductivity, oxidation reduction potential (ORP), and dissolved oxygen (DO) to verify ideal geochemical conditions for Dehalococcoides growth and proliferation. Dehalococcoides (KB-1®) were injected into the well through nitrogen infused tubing.
Long-term semi-annual groundwater monitoring was first implemented after the Dehalococcoides injection was completed. Select monitoring wells are sampled and analyzed for chlorinated VOCs, total organic carbon (TOC), nitrate, sulfate, dissolved gases (ethane, ethene and methane), metals (calcium, magnesium, potassium, and sodium) during each sampling event. Field measurements including pH, ORP, temperature, conductivity, dissolved oxygen, and turbidity are recorded prior to collecting laboratory samples. Analytical results indicate that TCE concentrations in the sources area are declining at an increased rate since the Dehalococcoides injection.
KEMRON conducted a VI study for the Northwest Boundary Area Groundwater Site. The soil gas survey was performed to collect an additional line of evidence to evaluate VI risk to buildings located over or near the delineated TCE Plume at the site. Several buildings were included in the assessment such as the Post Exchange, the armory, the veterinary clinic, the visitors control center, and the guard house. Soil gas vapor probes were installed via direct push borings at 18 locations throughout the study area. Grab soil gas samples were collected and analyzed by EPA Method TO-15. The soil gas data was evaluated in accordance with the EPA VI Calculator and Risk assessment processes. It was determined that the chlorinated groundwater plume is not impacting nearby buildings with VI of COCs.
Site CCFTB-039 has multiple sites with work scope necessary to accomplish finalization of the Corrective Measures Studies for these sites. Site specific RG were calculated by KEMRON’s risk assessment professionals for each site based upon COCs that were detected during the RFI present above EPA Regional Screening levels (RSL) or background concentrations for metals present at Fort Buchanan. RGs were presented by COC and the determination for any remedial action at each site is based upon concentrations of COCs being present above the RG. Site CCFTB-039 consisted of the following RFI sites: Site 2 Pesticide Burial Trench, Site 3 Spent Solvent Storage Area (Bldg 556), Site 9 Used Oil Storage Area (Bldg 556), Site 11 Heavy Equipment Storage Area (Bldg 556) and Site 12 Inactive Waste Disposal Area.