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Site Investigation Work Plan
<br /> Deuel Vocational Institution(DVI), Tracy, California Introduction
<br /> at this time. URS recommended an investigation to identify the PCE source near MW-9-BP in the Fourth
<br /> Quarter 2016 Groundwater Monitoring Report, Deuel Vocational Institution—Burn Pit(URS 2016c).
<br /> In December 2017,before the start of injection activities,the 4Q17 quarterly groundwater samples were
<br /> collected from the scheduled wells. The wells sampled were MW-2-BP and MW-5-BP (compliance
<br /> wells),MW-6-BP and MW-26-BP (treatment zone wells),MW-24-BP and MW-25-BP (transition zone
<br /> wells), and MW-7-BP (background well). VOC concentrations in 4Q17 (before EHC-L injections began)
<br /> generally were less than those reported in previous quarters, specifically at MW-9-BP (TCE at 34 gg/L,
<br /> PCE at 180 gg/L, cis-1,2-DCE at 11 µg/L), and MW-26-BP(TCE at 9.7 µg/L,PCE at 49 gg/L, and
<br /> cis-1,2-DCE at 82 gg/L),but still exceeded the MCLS in the burn pit area(URS 2017).
<br /> Between December 6 and December 12,2017, in situ remediation was implemented at the project site.
<br /> The remediation involved advancing 21 borings, spaced at 20 feet on center,using a Direct Push(DP)
<br /> drill rig to inject amendment in the areas around MW-26-BP and MW-6-BP, and immediately northwest
<br /> of MW-24-BP. The amendment was injected from the water table(approximately 10 feet bgs)to 25 feet
<br /> bgs, encompassing the screened interval of MW-26-13P. This well, located in the burn pit area,
<br /> historically had the highest VOC concentrations. The injection fluid consisted of EHC-L components
<br /> (EHC-L,ELS emulsion,DHC inoculum, and potassium bicarbonate as a buffer). In recent groundwater
<br /> monitoring events since this effort, groundwater at MW-9-BP has remained above the MCL for PCE and
<br /> TCE,prompting further investigation. (URS 2020)
<br /> Between August 17 and 31,2020, a PSGS was conducted to characterize the contaminants of concern
<br /> (CDCs)west of the burn pit area near MW-9-BP and the potential risk of vapor intrusion into site
<br /> facilities. The investigation used approximately three sampling probes implemented near MW-9-BP, four
<br /> sampling probes near the Grease Trap,two probes southeast of the Grease Trap and along a utility,two
<br /> probes placed outside the Laundry/Print Shop,three probes placed in the space beneath the former
<br /> Laundry and Print Shop, and one probe to the southeast near the administration area(see Figure 2).
<br /> Passive soil gas samplers were emplaced using a 3.5-inch-diameter hand auger. Each borehole was
<br /> advanced to 2 feet bgs. The samplers were retrieved on August 31,2020, approximately 2 weeks after
<br /> installation.
<br /> The investigation detected 14 analytes, including PCE, TCE, and cis-1,2-DCE,with maximum
<br /> concentrations of 4,470 micrograms per cubic meter(gg/m), 521 gg/m3, and 170 µg/m3,respectively.
<br /> These maximum concentrations were detected at SV-02. This investigation found at least one commercial
<br /> exceedance of PCE and TCE,prompting an SG investigation around SG-04 and SG-08. An IA/CS
<br /> evaluation near SG-2 (Laundry/Print Shop)and additional SG sampling around SG-12 (Grease Pit)will
<br /> also be conducted as part of this proposed investigation.
<br /> 1.5 Project Organization and Responsibilities
<br /> Responsibilities of the key URS project personnel are as follows:
<br /> • Project Manager,Ed Tarter,Professional Engineer(PE), is responsible for project coordination
<br /> for URS, CDCR, and other regional contractors for the management of all URS activities
<br /> associated with the project.His responsibilities include budget management,technical oversight,
<br /> and overall project quality. He also is responsible for coordinating activities specific to this
<br /> project, including activities involving the CVWB,URS, and subcontractors. He will ensure that
<br /> all project phases are executed efficiently,in accordance with the work order and project work
<br /> plan provisions, and he will assume responsibility for all technical, financial, and administrative
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