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INC.1 <br /> 6ETTLER - RYANN <br /> f : l <br /> August 28, 2000 J q�+�•°° <br /> Mr. Ed Ralston �t <br /> Tosco Marketing Company <br /> 1380 Lead Hill Road, Suite 120 <br /> Roseville, California 95661 <br /> Subject- Remedial Status Report For Tosco (Former BP Oil) Station No. 11195, <br /> 16500 South Interstate 5, Lathrop, California. <br /> ✓e " <br /> Mr. Ralston: <br /> At the request of Tosco Marketing Company (Tosco), Gettler-Ryan Inc. (GR) has prepared this <br /> report to document groundwater sampling, purging and d.isposal conducted for the subject site. <br /> Activities documented in this report were initially proposed in GR's Remedial Action Plan <br /> (RAP), dated June 21, 1999. A 6-inch diameter conductor casing was installed in the former <br /> gasoline UST pit backfill to access the groundwater beneath the site Conductor casing location <br /> and construction specifications were presented in GR's April 23, 1999 Underground Storage <br /> Tank and Product Piping Replacement Report and the aforementioned RAP. <br /> Groundwater Removal and Disposal <br /> Groundwater was removed from the former Underground Storage Tank (UST) pit by Onyx <br /> Industrial Services (Onyx) of Benicia, California and transported to the Tosco Refinery in <br /> Rodeo, California for disposal. During UST replacement activities, approximately 39,000 <br /> gallons were purged from the former UST pit during five separate events. From January 19, <br /> 1999 to April 25, 2000, approximately 153,260 gallons of groundwater were removed from the <br /> conductor casing and from well MW-5. Approximately 192,260 gallons of groundwater. were <br /> removed from the site. Groundwater removal totals and dates are summarized in Table 1. <br /> Groundwater Sampling <br /> Groundwater samples have been collected periodically from the conductor casing and analyzed <br /> for Total Petroleum Hydrocarbons as Gasoline (TPHg) by EPA Method 8015, and benzene, <br /> toluene, ethylbenzene, and xylenes (BTEX) by EPA Method 8020, and methyl tert-butyl ether <br /> (MtBE) by EPA Methods 8020 or 8260. The results have been used to document hydrocarbon <br /> concentration trends and comply with Tosco Refinery requirements. Sample dates and analytical <br /> results are summarized in Table 1. <br /> Groundwater Analytical Data and MISE Mass Removal <br /> Two grab groundwater samples were collected from the UST excavation on December 30, 1998 <br /> and five grab groundwater samples were collected from the conductor casing between February <br /> 1, 1999 and April 25, 2000. Two MtBE concentration averages were calculated for use in <br /> estimating the total of MtBE removed during groundwater purging from the UST pit. The first <br /> 6747 Sierra Court , Suite J • Dublin , California 94568 ( 925) 551 - 7555 <br />