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1 <br /> ARCADIS Ms. Kathryn Dominic ' <br /> August 24, 21 <br /> 1 <br /> • To assess whether the biotreatment of the TPCA pond soil achieved the cleanup ' <br /> goals provided in Cleanup and Abatement Order(CAO No. 92-707) <br /> This report includes a summary of the soil sampling methodologies, analytical ' <br /> methods and results. In addition, ARCADIS addressed comments 4a through 4e <br /> provided by the RWQCB in their February 19, 2009 Work Plan review letter during <br /> the assessment of whether the CAO cleanup goals have been achieved. ' <br /> Background Summary ' <br /> A more detailed background is provided in the Work Plan; however, a brief summary <br /> is provided herein to support the progression of activities. ' <br /> Soil containing up to 200,000 milligrams per kilogram (mg/kg) of total petroleum <br /> hydrocarbons (TPH)was excavated from the former TPCA pond and stored on site ' <br /> during 1987 and again during 1992. In 1994, the excavated soil was spread to a <br /> thickness of approximately 2 feet in two adjacent Biotreatment Beds covering 4.7 <br /> acres to facilitate bioremediation. Figures 2 and 3 show the TPCA pond and ' <br /> Biotreatment Beds 1 and 2. <br /> Prior to 1987, site storm water and oily wastewater from the Engine House was ' <br /> collected through a series of inlets and piping that discharged to a series of three <br /> surface impoundments. The surface impoundments acted as an oil/water separator. <br /> Water was discharged sequentially through the impoundments and finally to the ' <br /> sewer system. In 1987, after being notified that the surface impoundments contained <br /> hazardous waste and were subject to the requirements of TPCA, discharge to the <br /> impoundments ceased and underground piping associated with the impoundments ' <br /> was filled with concrete. <br /> Terranext Inc. (Terranext)completed an investigation of the TPCA surface ' <br /> impoundments and summarized below is the pertinent data: <br /> • 55 soil samples were analyzed for TPH-diesel range organics (TPH-d)and the ' <br /> average concentration was 595(mg/kg) <br /> • 15 soil samples were analyzed for soluble TPH-d using the DI WET and the ' <br /> average soluble concentration was 1,108 micrograms per liter(pg/1) <br /> Approximately 11,000 cubic yards of pond sludge and soil were excavated and ' <br /> stockpiled onsite. TPH-d and polynuclear aromatic hydrocarbons (PAHs)were the <br /> constituents of concern (COCs) identified in excavated sludge and soil (Terranext <br /> Page: <br /> 2/12 ' <br />