SITE INFORMATION AND CORRESPONDENCE

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fl I'. Mr. Gary Brophy 20 March 1989 1235 Slayton Drive Manteca, CA 95336 PRELIMINARY REPORT FOR FORMER TEXACO SERVICE STATION, 941 EAST YOSEMITE AVENUE, MANTECA, SAN JOAQUIN COUNTY Thank you for submitting the 3 January 1989 Freliminary Report (PR) for your site for our review, The PR is incomplete. Additional site information and investigative work is needed to complete the site assessment. Enclosed is a copy of our Tri -Regional Guidelines for•the initial evaluation and investigation of underground Unks, We are requesting that the following information be submitted to us and the San Joaquin Local Health District (SJLHO) in an Addendum to the 3 January 1989 PR by 7 April 1489: 1. Submit copies of the Canonie Environmental Services Laboratory Report No. 85-052-3380 and No. 85-052-3776 for samples collected in the tank pit on 11 February and 14 March 1988, respectively. 2. On a site map indicate the sample points for each sample collected from the tank pit on ll February and 14 March 1988. - 3. 988.3. On a site map label each tank by the contents they held. 4. On a site map show the layout of all existing and former product pipelines and specify their depth below grade. Were the pipelines removed when the tanks were excavated? If not, they need to be removed as required by the SJLHO, S. Supply specific details on the sewer and Water lines adjacent to the tank pit. What are their depths below grade and outside diameters? Are either of their trenches deep enough to act as conduits for hydrocarbon migration from this site? In the PR your consultant recommended excavating the "initial tank cavity" vertically to the ground water surface approximately 23 feet below grade. We recommend that the extent of hydrocarbon cont minated soil be defined prior to Initiating remedial action. The north, east nd west soil contamination boundaries are unknown, We can understand th reasoning for removing the source, but should soil contamination extend ver a wide area, it may be more cost effective to initiate some other type of remedial action other than —excavation�.� . . excavation of-only-the-tank-pit: _ _ v _ State regulations require that during tank removals a soil sample is to be collected beneath the product pipelines for every 20 lineal feet of pipeline. These soil samples are to be collected within the first two feet of native soil beneath the pipeline trench. These shal ow borings could be done using a hand auger.