ARCHIVED REPORTS XR0007969 - Laserfiche WebLink

Home Browse Search

' 16 December 2002 AGE-NC Project No 97-0300 ' Page 2 of 8 ' generally consist of moderate to poorly drained fine-textured soils The soils are generally derived from both marine and non-marine sediment, and are generally formed in alluvium derived from mixed rock sources ' The Modesto,Riverbank,Turlock Lake Formations and overlying recent alluvium are the principal source 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 nearest surface water feature in the vicinity of the property is the Calaveras River located approximately 2,500 feet north of the site ' Based on review of the Lanes ofEqual Depth to Groundwater Spring 1999 map published by the San Joaquin CountyFlood Control District and Water Conservation District(FCD&WCD),the estimated ' depth to ground water at the site is between 40 feet and 50 feet below surface grade (bsg) Review ofthe map Lanes ofEqual Elevation of Groundwater Sprang 1999(FCD&WCD)depicts the regional ground water flow direction towards the northeast 3.0. UNDERGROUND STORAGE TANK REMOVAL The three USTs were removed from the site on 24 February 1999 Soil samples were collected from beneath the tank pit and product piping and were submitted to a California Department of Health Services (DHS)-certified laboratory for analysis of the following petroleum hydrocarbons Total petroleum hydrocarbons quantified as diesel (TPH-d) and motor oil (TPH-mo) were detected in samples collected beneath product piping at concentrations ranging as high as 92 milligrams per kilogram (mg/kg), in TPH-mo Benzene, toluene, ethylbenzene and xylenes (BTEX compounds) were detected in samples collected beneath the USTs and product piping at concentrations ranging' as high asC` �mg/kg xylenes MTBE was detected in samples colle( kom stockpiled soil,piping ti and the bout end of the UST pit at concentrations as high as f 0 micrograms per kilogram oy" (gg/kg) Total lead was detected in samples collected beneath product piping at concentrations 3 Soo of ' ranging as high as 40 mg/kg t, alytical results of soil samples collected during tank removal V n°{ activities are summarized in Table 1 y ' p MCP eNle.. b, Based on field observations and analytical results of soil samples collected during the tank removals, "Q. ` UST unauthorized release/contamination site reports were filed by the SJCEHD on 01 March 1989 4 and 17 May 1999 (Appendix B), subsequently, the San Joaquin County Environmental Health IDepartment (SJCEHD) directed by letter, dated 03 June 1999, that a subsurface investigation be performed at the site to delineate the vertical and horizontal extent of the petroleum hydrocarbon- impact IAdvanced Geo Environmental,Inc