FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

05 August 2003 AGE-NC Project No. 03-1023 Page 2 of 4 Geology, 1977). Rocks composing the basement complex of the Province have not been completcly defined but are believed to be metamorphic and igneous in origin. The closest surface water feature to the site is the Stockton Diverting Canal, located approximately 1500 feet northeast of the site. Water from the Diverting Canal drains into the Calaveras River and then to the San Joaquin River Deep Water Channel. The Modesto, Riverbank and Turlock Lake Formations and overlying Recent alluvium are the principal sources of domestic ground water in the 13,500-square mile San Joaquin Valley Ground Water Basin (Basin 5-22). Based upon well information obtained from nearby sites, ground water flow direction in the vicinity is northerly and is currently estimated to occur at a depth of approximately 50 feet below surface grade (bsg). Ground water occurs in a generally sandy layer extending from approximately 40 feet bsg to 60 feet bsg. The sedimentary units are relatively horizontal and continuous over the area. 2.2. UNDERGROUND STORAGE TANK REMOVAL Three USTs and the associated piping and dispenser island were removed from the site on 02 April 2003; two of the USTs had dispensed diesel fuel and gasoline, respectively, and one had been utilized for waste oil. At the time of tank removal, a total of seven soil samples were collected from beneath the USTs and dispenser island and three soil samples were collected from the excavated soil and transported to Cal Tech Environmental Laboratories (CTEL), a California Department of Health Services certified laboratory, for analysis. The laboratory analysis detected total petroleum hydrocarbons quantified as diesel and gasoline (TPH-d and TPH-g) in sample D-2 (dispenser island) at 590 milligrams per kilogram (mg/kg or parts per million) and 1.1 mg/kg, respectively; TPH-d and TPH-g were also detected in the stockpiled soil sample STK-1 at concentrations of 81 mg/kg and 1.3 mg/kg, respectively. In addition,methyl tertiary butyl ether(MTBE)was detected in a soil sample collected beneath UST-1 at 0.031 and xylenes were detected in a sample from the stockpiled soil at a concentration of 0.073 mg/kg. The laboratory report(CT214-0304018)and chain-of-custody forms are presented in Appendix A. Based on analytical results of soil samples collected during the UST removals, a preliminary evaluation and investigation was required by the San Joaquin County Environmental Health Department (EHD) by letter dated 23 April 2003 (Appendix B). Advanced GeuEnvirunmental.Inc.