ARCHIVED REPORTS_XR0007197 - Laserfiche WebLink

Home Browse Search

24 March 2000 AGE-NC Project No 97-0141 Page 2 of 9 RESNA Industries of Escalon, California Evidence of petroleum hydrocarbon soil contamination was detected in all borings at depths between 20 and 35 feet below surface grade(bsg) Initial ground water samples contained total petroleum hydrocarbons quantified as gasoline (TPH-g) at concentrations as high as 300,000 ,ugll (micrograms per liter or parts per billion ppb) and volatile aromatics (benzene,toluene, ethylbenzene and xylenes BTEX) at concentrations as high as 17,000 µg/I A fourth groundwater monitoring well was installed down gradient of the former UST area in October 1993 Evidence of petroleum hydrocarbon soil contamination was detected in soil samples collected at 40 and 45 feet bsg Furthermore, initial ground water samples detected TPH-g at concentrations as high as 6,800,ugll and BTEX at concentrations as high as 1,400 pgll In May 1994, a fifth ground water monitoring well (MW-5) was advanced near the northeast corner of the site Petroleum hydrocarbons were not reported in soil samples submitted for analysis TPH-g and BTEX were reported in initial ground water samples collected from MW-5 at concentrations up to 93 pg/l and 1 3 ug1l, respectively . Between March 1992 and October 1999, ground water samples have been collected from various wells at the site on eight occasions The most recent sampling, which included wells MW-1 through MW-5, occurred on 07 October 1999 During the October 1999 sampling, samples from MW-1 was reported to have the highest concentrations of TPH-g and BTEX Samples collected from wells MW- 4 and MW-5 were non-detect for TPH-g and BTEX No fuel oxygenating compounds were reported in any of the samples collected in October 1999 Ground water elevation was above the slotted screened intervals of all wells at the site during the October 1999 sampling A copy of the laboratory report from the October 1999 sampling is attached 23 REGIONAL GEOLOGIC SETTING According to the Geologic Map of California, published in 1977 by the State of California Department of Mines and Geology, the site area is within the Great Valley Geomorphic Province of California, a large, elongate, northwest trending structural trough The Great Valley Province has been filled to its present elevation with thick sequences of sediment ranging in age from Jurassic to present day, creating a nearly flat lying alluvial plain extending from the Tehachapi Mountains in the south to the Klamath Mountains in the north The western and eastern boundaries of this province are comprised of the California Coast Range and the Sierra Nevada Mountains, respectively The Great Valley Province is subdivided into two mayor divisions designated the Sacramento and San Joaquin Valleys Advanced GeoEmiranmental,Inc