Building 700, 7353, AGL, and 600/615 – Fort Riley, KS
- Groundwater Investigation
- Soil and Sediment Investigation
On 1 January 2019, Bluestone acquired Avatar Environmental, LLC. Under our HTRW contract with CENWK,Bluestone (Avatar)has been the Prime contractor responsible for all aspects of work performed at Fort Riley since 2012 under the IRP through four separate Task Orders. The Fort Riley project demonstrates our technical competence in performing CERCLA investigations at an installation with chlorinated solvents and petroleum compounds in soil and groundwater.
Sites investigated have included groundwater investigations at an active POL Tank Farm; soil and groundwater investigations at former gasoline stations, leaking UST sites and abandoned gas lines; a Pre-Design investigation for a solvent spill area; and a pilot study and remedial design at a TPH- and VOC-contaminated site.
Bluestone has prepared work plans and UFP-QAPPs for all sites and CENWK and the Kansas Department of Health and Environment (KDHE) approved the plans with few revisions. In addition, Quality Control Summary Reports (QCSRs) and Annual Summary Reports (ASRs) were prepared for groundwater sampling of wells at the POL Tank Farm. Field tasks included: low-flow groundwater sampling for BTEX, naphthalene, VPH, EPH, nitrates, nitrites and ammonia; microbial trap deployment for 45 days in two wells for microbial analyses; and free product removal and analyses to determine product degradation. Increasing benzene concentrations above MCLs in groundwater samples from two monitoring wells downgradient from the Tank Farm led Bluestone to recommend installation of two additional bedrock monitoring wells to define the extent of the plume which was subsequently achieved.
This project description focuses on Task Order 0005. On this Task Order, Bluestone performed a site investigation to characterize the nature and extent of contamination in the soil and groundwater at four POL sites on the Post – Building 700, Building 7353, Buildings 600/615, and the Abandoned Gas Line (AGL) Terminus Area.
At Buildings 7353 and 600/615, the area surrounding former Underground Storage Tanks was investigated through a soil and groundwater investigation to complete site closure in accordance with KDHE requirements. Closure reports were prepared and accepted by KDHE with no revisions.
At the AGL site, Bluestone performed additional delineation of the groundwater on the river side of the Kansas River levee to monitor the groundwater plume. The Kansas River is a Tier 2 water body used as a drinking water source and has high recreational value, so in accordance with the Kansas Anti-Degradation Policy, sampling was conducted to monitor water quality. Borings were completed on the side of the levee, which required coordination with the Geotechnical and Dam Safety Section at the Corps of Engineers. Three years of groundwater sampling from existing monitoring wells consisting of two semi-annual sampling events, and one high-water event, were conducted in 2015, 2016 and 2017 at the AGL Terminus monitoring wells. The high-water event is based on the stage of the nearby Kansas River meeting a specific flow measurement to determine if contaminants are mobilized during periods of high water table. Field teams were able to mobilize rapidly to collect groundwater samples during the high river stage. Two additional years of semi-annual and high-water sampling have been authorized for 2018 and 2019. The first three Long-Term Monitoring Reports were prepared combining a large data set of historical environmental chemistry data with current data and were approved by KDHE with no changes.
The scope of the additional investigation at the Building 700 former gas station site was developed in collaboration with the CENWK team and the Fort Riley team to choose soil-boring locations to supplement the previous sampling that had been done at the site. GIS working maps were prepared and updated weekly with PCE results during a 3-week field program to assess the results from the field laboratory and distributed to the project team to discuss results and next steps. Daily phone calls with the Army points of contact allowed for efficient field program implementation.
A Human Health Focused Risk Assessment to evaluate potential risks to human health was completed at the former Building 700 site. Exposure to site contaminants for current and future outdoor workers was evaluated. Remedial alternatives including soil vapor extraction were also evaluated. Conclusions from the site investigation and focused risk assessment were used by the team to prepare a Remedial Evaluation to evaluate closure options for the site. Several remedial technologies were screened and evaluated to address the TPH and VOC contamination, including soil vapor extraction and air sparge, and excavation and in-situ treatment. Based on effectiveness, implementability, and cost, excavation and in-situ treatment were recommended.
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