Laserfiche WebLink
l i '1 <br /> 7ERI <br /> . ENVIRONMENTAL RESOLUTIONS, INC. <br /> October 30, 1998 <br /> ERI 205513 QS6 <br /> Mr Ed Ralston <br /> Tosco Marketing Company <br /> 1380 Lead Hill Road, Suite 120 <br /> Roseville, California 95661 <br /> Subject Quarterly Summary Report for Environmental Investigation, hird Quarter 1998, <br /> Tosco 76 Service Station 5886, 2701 March Lane, Stockton, a <br /> Mr Ralston <br /> At the request of Tosco Marketing Company (Tosco), and pursuant to correspondence from San <br /> Joaquin County Public Health Services, Environmental Health Division (the Counn) dated July 24, <br /> 1997, Environmental Resolutions, Inc (ERI) is submitting this quarterly summary report for the <br /> subject site <br /> BACKGROUND <br /> The site is immediately west of Interstate I-5 on the northwestern corner of March Lane and the I-5 <br /> offramp in Stockton, California, as shown on the Site Vicinity Map (Plate 1) The locations of the <br /> existing underground storage tank (UST) field, dispenser pump islands, other selected site teatures, <br /> and surrounding properties are shown on the Generalized Site Plan (Plate 2) Properties in the <br /> vicinity of the site are generally occupied by commercial developments <br /> It is ERI's understanding that Unocal Corporation purchased the Iand in 1967, at "Nhich time the <br /> property was vacant In 1982, Unocal constructed a service station at the site and installed three <br /> 12,000-gallon UST's to store gasoline and diesel fuels (Delta Environmental, February 6, 1996) <br /> Between July 1995 and September 1996, Unocal replaced the original UST's and associated product <br /> distribution lines, enlarged the existing tank pit to accommodate three new 15,000-gallon UST's, <br /> advanced 21 soil borings and collected soil and groundwater samples from the borings utilizing a <br /> Geoprobe® sampling system, and drilled four additional soil borings and constructed-groundwater <br /> monitoring wells in three of these borings The location of existing wells are shown on Plate 2 <br /> Unocal initiated quarterly groundwater monitoring during December 1996 Data collected by others <br /> indicate the groundwater flow direction ranges from northwest to southwest and the groundwater <br /> surface ranges from approximately 5 to 9 feet below ground surface (ft bgs) <br /> In April 1997, ERI performed an investigation to evaluate the source and extent of methyl tertiary <br /> butyl ether (MTBE) (ERI, June 3, 1997) The investigation included hand-auguring three soil borings <br /> adjacent to surface features (i a catch basins), drilling four soil borings and constructing dual <br /> completion groundwater monitoring wells (MW4S/D through MW7SID) at discreet depths in the <br /> \ 74 Digital Drive, Suite 6,Novato, California 94949 415-382-9105 (FAX 415-382-1856) <br /> Lake Forest • Novato • Seattle <br />