ARCHIVED REPORTS XR0001831 - Laserfiche WebLink

Home Browse Search

�h1 Immediately beneath the alluvial sediments are older, predominantly lake bed deposits These lie unconformably on Mio-Pliocene marine and non-marine sediments, which extend to a crystalline basement at a depth of approximately 6,000 feet bgs at the site At the subject site, surface deposits consist of Quaternary (recent) unconsolidated alluvium overlying Quaternary (Pleistocene) nonmarine sediments Geologic deposits in the study area include Pleistocene alluvial sediments that form a homocline dipping gently to the southwest The deposits are alluvium consisting of poorly indurated and dissected fan deposits (California Division of Mines and Geology, 1977) The alluvium consists of silty sands and fine-grained to medium-grained sands, with intervals of finer grained, sandy silts and minor development of clay overbank deposits Surface water and groundwater in the Sacramento Valley are derived predominantly from the Sierra Nevada to the east and are transported by seven major rivers, the closest to the site being the Mokelumne River The subject site is located approximately %2 mile south of the Mokelumne River(Figure 4) The depth to the regional, unconfined aquifer is approximately 45 feet bgs at the site This is supported by a April 1, 2003 measurement of the groundwater elevations in three existing monitoring wells at the site (Muir, 2003). 5. TANK HISTORY: On February 2, 1988, Ramcon applied for a permit to PHSEHD to remove the six UST"s at the site On February 5, 1988 the UST's were removed from the subsurface and reportedly transported to H&H Ship Service Company, a metals recycling . business located in San Francisco, California under hazardous waste manifest All dispensers and underground piping were also reportedly removed Soil samples were reportedly collected from underneath each of the UST's and transported under chain of custody document to GT Environmental Laboratories in Concord, California for analysis as follows USEPA Test Method 8020/8015m/5030 and 8010 for volatile organic compounds In addition, the soil samples were reportedly analyzed for EDB and total lead (Applied Geosystems, 1988) Analytical laboratory reports from GT Environmental Laboratories for the soil samples submitted for analysis were all reported to contain elevated concentration of volatile organic compounds (VOC's) beneath each of the UST's Maximum concentrations in the samples were reported as follow benzene (14 mg/kg), toluene (200 mg/kg), ethylbenzene (130 mg/kg), xylene (850 mg/kg), TPH-gasoline (4,700 mg/kg) and miscellaneous hydrocarbons (C4 to 12) (3,400 mg/kg) Ethylene Dibromide concentrations in soil samples submitted was reported as below analytical method detection limits Total lead content for the soil samples was reported to range from non-detection to 8 mg/kg Significant soil petroleum hydrocarbon contamination was reportedly present under the former 9,950 gallon UST (Figure 3) (Applied GeoSystems, 1988) Apparently RAMCON conducted a limited overexcavatzon of the petroleum hydrocarbon contaminated soil and stockpiled the soil on site It is estimated that approximately 100 • Mam\D\Environmental\ParmarTexaco\WorkplanV42003 wpd 5