Laserfiche WebLink
3 <br /> Woodward-Clye.a .� <br /> Ms. Diane 11mson <br /> San Joaquin County Environmental Health Division <br /> February 23, 1996 <br /> Page 2 <br /> of the UST, one small hole was observed on the bottom of the tank beneath the fill end (north end). <br /> Approximately 18 cubic yards of diesel contaminated soil were excavated during the tank removal and <br /> were transported to Forward Incorporated Landfill of Stockton, California under non-hazardous waste <br /> manifest job acceptance#94-671. Confirmatory soil samples were collected from the excavation after <br /> the removal of the contaminated soil. <br /> The UST excavation was backfilled with imported sand, clean excavated material, and imported pea <br /> gravel under the supervision of WCFS and the San Joaquin County Environmental Health Division <br /> (SJCEHD). The excavation was lined with a polyethylene sheeting. The sheeting was placed at depths <br /> ranging from 9 feet bgs on the south end of the pit to 18 feet bgs on the north end of the pit. The <br /> backfill materials were placed above the polyethylene sheeting to approximately 10 inches bgs and <br /> were then covered over with the remaining ends of the sheeting. The excavation was completed to <br /> surface grade with clean excavated soil. <br /> Analytical results of the confirmatory soil samples later indicated that the excavation was free of <br /> contamination except on the north end. One sample collected from the north end of the excavation, at <br /> approximately 18 feet below ground surface (bgs), contained concentrations of 9000 mg/Kg total <br /> petroleum hydrocarbons(TPH)as diesel. An"Analytical Results Report" describing the removal of the <br /> FEMA owned UST at the KJAX site was prepared by WCFS in May 1994. A site investigation was <br /> conducted in response to a letter to FEMA from SJCEHD dated December 27, 1993. <br /> Site Characterization Activities <br /> Site Characterization Activities were conducted from May 25 through June 22, 1995 to assess the <br /> lateral and vertical extent of diesel contaminated soil in the vicinity of the former UST. Investigative <br /> activities included advancing seven soil borings. Five borings were advanced to approximately 30 feet <br /> bgs,-one was advanced to 51 feet bgs, and one was advanced to 100 feet bgs. A total of 36 soil <br /> samples were collected during the site characterization activities. Concentrations of TPH as diesel <br /> were found in soil samples collected from three borings adjacent to and within the north end of the <br /> former tank excavation. Concentrations were below the allowable limit (100 mg/Kg) set forth in the <br /> State of California Tri-Regional Board Staff Recommendations and the Leaking Underground Fuel <br /> Tank Guidelines which apply to the KJAX site. Groundwater was encountered in the boring drilled to <br /> 100 feet, and a groundwater sample was collected. No detectable concentrations of TPH as diesel, <br /> TPH as gasoline, or benzene, toluene, ethylbenzene, and total xylenes (BTEX) were reported for the <br /> groundwater sample. A Preliminary Investigation and Evaluation Report (PIER) describing the site <br /> investigation activities at the KJAX site was prepared by WCFS and submitted to SJCEHD in August <br /> 1995. <br /> Based on analytical results from the tank removal program and the site characterization, it appears that <br /> contaminated soil in excess of 100 mg/Kg exixts in the north end of the former UST excavation at an <br /> approximate depth of 18 to 22 feet bgs. Furthermore, the polyethylene liner left in the excavation <br /> Woodward-Clyde Federal Services <br /> 8054z:\continv.ust\kjax.ca\reports\wkpin.jax <br />