ARCHIVED REPORTS_XR0013013 - Laserfiche WebLink

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� L ' EXECUTIVE SUMMARY i During. 1990, a 265,000 gallon capacity underground storage tank (UST) was removed f by O.H. Materials Company (OHM) from property owned by Sheldon Oil Company (Sheldon) in Stockton, California and leased by Kent's Oil, The Kent's Oil facility (Site) is operated as an asphalt blending plant. The•tank had been used-by Kent's ,Oil for storage of asphalt oil.• } During UST removal, it became apparent that the UST had leaked and surrounding soils had been affected by asphalt oil. In 1993, a work plan was prepared by Aprotek and submitted to and approved by San Joaquin County Public Health Services Department (County) that proposed excavation and bioremediation of 1,000 cubic yards of soil that had been affected by the leaking F j UST. Upon completion of excavation of the 1,000 cubic yards of soil, it was apparent that additional hydrocarbon-affected soil was present. 3 The County approved a work plan, prepared by Brown and Caldwell (BC), for the ' assessment of the extent of the hydrocarbons in the soil. Five soil borings were drilled by BC i and soil and groundwater samples were collected from the borings. The results from the drilling and sampling indicated that groundwater was present at approximately 80 feet below ground M surface (bgs) and it had not been affected by the asphalt oil. Analytical results of the soil samples collected as a part of this additional investigation identified petroleum hydrocarbon i constituents at varying depths up to 43 feet bgs beneath the former UST. As agreed upon by Sheldon and the County, additional excavation of soil was conducted by Aprotek in August 1993. Depth and lateral extent was determined by visual identification of , affected soil. The sidewalls and bottom of the excavation were sampled and analyzed to evaluate whether further excavation was required. Soil samples were collected by BC under the I supervision of a representative from the County. The. final-size- of the excavation was, 4 f approximately 65 feet wide by 100 feet-long and ranged in depth from 20 to 45 feet bgs. A total, L of approximately 12,000 cubic yards of soil were excavated. 4 The size of the excavation was limited by railroad tracks located to the south, above ground storage ,tanks located to the north and east, physical constraints to the west, and safety constraints. Therefore, some petroleum hydrocarbon affected soil was left in place in the wester half of the excavation underneath the access ramp used by the excavator. i Bioremediation pilot test of the soil using FryeZeme""' enhance bioremediation, a i proprietary process which utilizes accelerated enzyme catalyzed metabolic remediation, was conducted by International Intervals. A biocell was constructed and the bioremediation product i was applied to the soil once a week for eight weeks three different times. However, the results This report was prepared in accordance with the standards of the environmental consulting industry at the time it was M prepared. It should not be relied upon by parties other than those for whom it was prepared,and then only to the extent of the scope of work which was authorized. This report does not guarantee that no additional environmental contamination beyond that described in this report exists at the site. i f E i7f27a93'£'J603VtFPOR'[SICEIYTA[LC10 _ Q%4S-PS22N .F 4