ARCHIVED REPORTS_XR0005367 - Laserfiche WebLink

Home Browse Search

On August .18, 1986 Integrity Tank Testing Systems, Inc. of Stockton, California conducted tightness testing of the 750 gallon (gal.), and 1000 gal. waste oil UST's located at the subject site. Both tanks were within the NFPA 329 Guidelines of a maximum loss of.05 gallons per hour for a tight tank/system. On July 29, 1987 Walker Hydraulics of Pleasant Hill, California removed the 750 gal. and 1000 gal. UST's. Soil samples were collected at the fill port ends of each tank. One sample was collected at 12 ft below ground surface beneath the 750 gal. UST. The laboratory analytical results indicated total petroleum hydrocarbon (TPH) concentrations of 370 ppm and total xylenes at a concentration of 44 ppm. One sample was also collected at 14 ft below ground surface from the fill port end of the 1000 gal: UST. TPH was detected at a concentration of 360 ppm and total xylenes were detected at a concentration of 58 ppm. On September 1, 1987 personnel from Canonie Environmental of Stockton, California collected additional soil samples from the former UST pit. The samples were collected using a backhoe at approximately the same locations as the initial samples collected during the UST removal, but a depths of 16.6 ft (beneath the former 750 gal. UST) and 16.5 ft below ground surface (beneath the former 1000 gal. UST). Analytical results for the sample collected from 16.6 ft were not • available. Results for the 16.5 ft sample indicated TPH concentrations of 2,000 ppm and total xylenes at a concentration of 1,000 ppm. (Soil Assessment Report, 10-9-87. Kleinfelder. File # 24-2072-1) On September 25, 1987 a geologist from Kleinfelder of Sacramento, California collected twelve soil samples from a stockpile of soil removed during the tank removal. Four of the samples contained detectable concentrations of TPH. Laboratory analytical results indicated that one sample contained concentrations of TPH as diesel at 13 ppm. The other three samples contained concentrations of TPH as gasoline ranging from 170 ppm to 1900 ppm. Kleinfelder indicated that the stockpiled soil had been segregated based on the sampling locations and laboratory results. (Soil Assessment Report, 10-9-87. Kleinfelder. File# 24-2072-1) On'approximately October 27, 1987 Mr, Jay Friedman of Valley Volkswagen and Mr. Ray Walker of Walker Hydraulics backfilled the UST pit with the stockpiled soil. Apparently the petroleum hydrocarbon impacted soil was placed at the top of the backfilled UST pit. (Telephone Conversation Record, 10-27-87. Kleinfelder) REGIONAL GEOLOGY AND HYDROLOGY The site is situated in central Stockton, San Joaquin County, California. Regionally the property is located in the San Joaquin Valley physiographic province. The valley is a topographic and structural basin bounded on the east by the Sierra Nevada and on the west by the Coast Ranges. 5