ARCHIVED REPORTS_XR0009516 - Laserfiche WebLink

Metadata

Thumbnails

Annotations

' gasoline fuel as a result of the leaking UST. The following sections provide a brief summary . of previous environmental investigation work conducted at the site. ' 2.1 Underground Storage Tank Removal On 5 January 1988 Mr. George Lechich dba Valley Showcase signed an administrative ' agreement with San Joaquin Local Health District (SJLHD) to submit a closure plan for the UST on or before 5 February 1988. On 19 January 1988 Jim Thorpe Oil, Inc. filed an application with SJLHD on behalf of Valley Showcase to remove the 500-gallon UST from the ' site. The application was approved by SJLHD and the UST was removed on 11 February 1988. During removal one soil sample was collected from thirteen feet bgs (the maximum depth of the backhoe) at the western end of the tank excavation. Mr. W.R. Sanvely from ' SJLHD witnessed the tank removal and soil sampling and made note of a small hole in the bottom of the tank and that the soil sample was gray in color with a petroleum odor. Groundwater was not encountered during in UST excavation. ' The soil sample was collected from the backhoe bucket by Canonie Environmental Services and delivered to the laboratory following proper chain-of-custody procedures. The soil sample was analyzed for benzene, toluene, and xylene by U.S. Environmental Protection Agency (EPA) Method 8020 and for total petroleum hydrocarbons (TPH) by EPA Method mod8015. Laboratory results indicated the soil sample contained 1000 parts per million (ppm) TPH, 150 ppm toluene, and 370 ppm xylenes. Benzene was not detected (ND) above the laboratory detection limit. UST removal activities and results are documented in the UST closure report prepared by Wm. J. Hunter & Associates. ' . Because analytical results indicated site soils had been impacted with petroleum hydrocarbons, SJLHD issued a directive to assess the extent of impact to soil and groundwater at the site. ' 2.2 Site Assessment and Groundwater Monitoring Well Installations A work plan was prepared by Wm. J. Hunter & Associates (1993) in response to the SJLHD ' directive to assess the extent of soil and groundwater contamination at the site. Site assessment activities were performed in March 1994 after the work plan had been approved. ' As part of the site assessment, three groundwater monitoring wells (MW-1, MW-2, and MW-3) were installed in the vicinity of the former UST. Each well was installed to approximately 30 feet deep and screened from approximately 15 to 30 feet bgs. The locations of the monitoring ' wells are shown in Figure 2. Soil samples were collected for analysis at 5-foot intervals during installation of the monitoring well bore holes. Results from soil sample analyses in borehole MW-2 indicated the presence ' of total petroleum hydrocarbons as gasoline (TPH-g) and BTEX at the soil-groundwater interface at approximately 20 feet bgs (Wm. J. Hunter & Associates, 1994). Maximum concentrations of TPH-g and BTEX were detected in the 15.5 feet bgs soil sample collected from the.borehole MW-2. This.sample.contained. 1,200.ppm .TPH-g, 1.1_ppm of benzene, 1.3 -- - — V~vppm of toluene, 5 ppm of ethylbenzene, and 3.0 ppm of total xylenes. No soil contamination was detected in boreholes MW-1 and MW-3 (Wm. J. Hunter&Associates, 1994). TPH-g and BTEX were detected in the groundwater sample collected from monitoring well MW-2. Groundwater samples collected from monitoring wells MW-1 and MW-3 did not ' contain TPH-g and/or BTEX (Wm. J. Hunter & Associates, 1994). The site assessment report was prepared by Wm. J. Hunter & Associates (April 1994). 2 JJW GEOSCIENCES InC.