ARCHIVED REPORTS XR0000363 - Laserfiche WebLink

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1 GERAGHTY & MILLER, INC 3 biosparging system A groundwater extraction system was previously operated at the site, but is no longer in use PETROLEUM HYDROCARBONS IN SOIL ' An unquantified release was detected in a product line at the Chevron site in 1985 The highest concentrations of TPH as gasoline and BTEX in soil have been detected in samples ' collected between 15 and 20 feet bgs,in the zone of seasonal water-table fluctuation Although no holes were detected in the tanks removed in 1989, the former tanks and pump islands ' appear to be the primary source of subsurface contamination. A graphical summary of maximum concentrations of petroleum hydrocarbons in soil ' for all monitoring wells, soil borings, and remediation wells is shown in Figure 3 A summary of previous assessment activities at the site is presented in Attachment 1 Soil samples collected from below the excavated tanks contained concentrations of u P P ' to 3,600 milligrams per kilogram (mg/kg) total petroleum hydrocarbons (TPH) as gasoline and 31 mg/kg benzene. Samples were also collected from beneath the former north and south product lines during tank removal No analytes were detected beneath the south product line However, 310 mg/kg TPH as gasoline and 0.63 ppm benzene were reported in soil samples collected from beneath the north product line Soil samples collected from beneath the waste- oil tank did not contain TPH as gasoline or benzene above the laboratory method detection limit, although 1.1 ppm TPH as diesel was reported An additional sample collected from ' below the waste-oil tank was analyzed for total oil and grease (TOG), halogenated volatile organic compounds (HVOCs) (USEPA Method 8010), and pesticides and polychlorinated ' biphenyls (PCBs, USEPA Method 8080), no constituents were detected Total petroleum hydrocarbons in the gasoline range and benzene were not detected in ' soil samples collected from Wells MW-3, MW-4, MW-6, MW-7, or MW-8 Petroleum hydrocarbons in excess of 100 ppm were found in soil samples collected from the former tank- pit area(1VIW-1, MW-5, SB-2, SB-3, and VW-1) Petroleum hydrocarbons were also detected in soil samples collected from SB-1, SB-4, and SB-9 at a maximum concentration of 14 mg/kg ' TPH as gasoline and 0 09 mg/kg benzene. Sod samples were collected by Touchstone Development from below product lines removed during a recent station renovation in November 1996. Twelve soil samples were collected from depths of 3 feet to 4 feet bgs Maximum concentrations of TPH as gasoline and Project No RC0309.010