FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

_ 20 October 2004 AGE-NC Project No. 04-1156 Page 2 of 6 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). This basin is drained primarily by the San Joaquin River. The closest surface water feature to the site is French Camp Slough, located approximately 1,000 feet north. Water from the slough drains into the San Joaquin River Deep Water Channel and is primarily used for commercial and recreational boating. Based upon ground water monitoring well inforlrlation obtained from sites in the area, ground water flow direction is southeast to easternly and currently occurs at a depth of approximately 30 to 40 feet bsg within ground water wells. The sedimentary units are thought to be relatively horizontal and continuous over the area. 2.3. UNDERGROUND STORAGE TANK REMOVAL In October 1999, three USTs and associated piping were removed from the site under permit from the San Joaquin County Environmental Health Department(EHD). Six soil samples were collected fi-om the UST excavation; six soil samples were collected from the dispenser island area; and two 2:1 composite soil samples were collected from the excavated (stockpiled) soil. Total petroleum hydrocarbons quantified as gasoline(TPH-g)were detected in one sample from the dispenser island area (sample Db) at 625 milligram per kilogram (mg/kg). Toluene, ethyl benzene and total xylenes (TEX)were detected in the same sample at concentrations of 6.95 mg/kg, 373.55 mg/kg and 6.5 mg/kg, respectively. Methyl tertiary butyl ether (MTBE) was detected in UST excavation samples T2N, T2S and T3N, at concentrations of 3.26 mg/kg, 17.97 mg/kg and 15.1 mg/kg, respectively. No other target analytes were detected in samples collected during the UST removal. Analytical results of soil samples collected during UST removal procedures are in Appendix A of the AGE-prepared Prelintinat y Site Assessment Work Plan, dated 31 March 2004. Soil excavated during removal of the USTs was placed back into the excavation. 3.0 PROCEDURES Field work was conducted in accordance with guidelines established by the CVRWQCB for the investigation of UST sites and the EHD for sampling of ground water monitoring wells. Soil boring installation and sampling procedures for the site were outlined in Prelitrtinan)Site Assessinent Work Plan dated 31 March 2004, prepared by AGE and approved by the EHD by letter dated 27 April 2004. Advanced Gen Environmental,Inc.