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WATERWORK `.. ..r <br /> GEOCHEMICAL • GEOTECHNICAL ENVIRONMENTAL <br /> May 6, 1988 <br /> Mr . David Gar 1s <br /> San Joaquin Local Health District <br /> 1601 East Hazelton Avenue <br /> Stockton, CA 95201 MAY 12 1983 <br /> Dear Mr . Carls, ENVipomE"-JAL 11�,ATH <br /> PERtrSCi/�y� ;;,..a <br /> As required by the San Joaquin Local Health District (SJLHD) , the <br /> following letter outlines our proposed methodology to conduct a <br /> site investigation of potential groundwater contamination at the <br /> Ruiz Grocery, 9991 West Durham Ferry Road, in Tracy (Figure 1) . <br /> It is our understanding that gasoline contaminated soils were <br /> noted during the drilling of two soil borings adjacent to a 1000- <br /> gallon underground (u/g) storage tank which contained unleaded <br /> gasoline . Hydrocarbon contamination was confirmed by laboratory <br /> analysis of four soil samples collected from the two borings . <br /> Laboratory analysis of an old water well located approximately 75 <br /> feet from this tank did not record the presence of gasoline <br /> hydrocarbons above method detection limits . This well has <br /> subsequently been abandoned . A new well installed near the <br /> abandoned well in December 1987 was tested and did not record <br /> total petroleum hydrocarbons (as gasoline ) above the 100 parts <br /> per billion (ppb) detection limit . Additional testing of this <br /> well for the benzene, toluene and xylene is scheduled to be <br /> conducted . As agreed to by the SJCHD, WaterWork proposes to <br /> assess the extent of hydrocarbon contamination in a phased <br /> approach by initially drilling and sampling one groundwater <br /> monitoring well . A workplan to conduct the investigation is <br /> presented below. <br /> WORKPLAN <br /> 1. Existing data collected from previous investigations and <br /> the hydrogeology of the area will be reviewed. <br /> 2. Prior to initiating any field activities, Underground <br /> Service Alert (USA) will be contacted to locate underground <br /> utilities at the site . <br /> 3. One soil boring will be drilled to a depth of 15 feet below <br /> the water table to provide for installation of a groundwater <br /> monitoring well . Depth to water is believed to be approximately <br /> 16 feet below grade in the area of the site . Drilling will be <br /> conducted with a hollow stem auger drill rig under a California <br /> C57 license, as required . To define the lateral extent of soil <br /> and potential groundwater contamination in the direction of the <br /> existing domestic water supply well, the monitoring well will be <br /> placed between this well and the leaking u/g tank (Figure 2 ) . <br /> The well will be constructed of two inch F480 PVC casing and <br /> completed as shown on Figure 3 . <br /> 1485 EXPOSITION BLVD., SUITE 456 • SACRAMENTO, CA 95815 • (916) 921-1215 <br /> FRESNO. CA (209)431-8035 • SAN LUIS OBISPO,CA (805)544-6586 • RENO, NV (702)788-6830 <br />