FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

UNDE GROUND STORAGE TANK CLOSURE IN-PLACE AND SOIL SAMPLING REPORT San oaquin County Record Center 630 N.California Street Stockton,California 1.0 INTRODUCTION On March 29, 2012, Condor Earth Technologies and Jim Thorpe Oil excavated and closed in-place one underground storage tank (UST) at the San Joaquin County Records Center(Site), located at 630 North California Street in Stockton, California, Figure 1, Appendix A. Condor Earth Technologies, Inc. (Condor) was retained by San Joaquin County Facilities Management Division (Client) to provide sampling and reporting services. Thi 3 report includes a description of the fieldwork, discussion of laboratory analyses, and conclusions and recommendations based on the laboratory analytical results of the soil samples collected at the Site. 2.0 PROJECT BACKGROUND A vent pipe consistent with those typically found associated with historic USTs was located immediately south of the west doorway to thew ehouse along the exterior wall, Figure 2, Appendix A. Condor acquired historic Sanborn® Fire Insurance Maps and City Directories (Appendi?c C) to ascertain the history of the Site. Prior to 1917,the Site was the location of the Stockton Electric Railroad Company car house and blacksmith repair shop. Tlie buildings (current County Records Center and adjoining warehouse) located at 630 N. California Street were originally constructed in 1917, occupied by the Stockton Transfer Company. By 1940, the Site buildings were occupied by the Stockton Transfer Company and H.S. Dawson Van and Storage, possibly one company or two companies sharing the buildings. The warehouse contained vans and automobiles according to the 1950 Sanbom® Map. From at least 1970 until 1984, the warehouse was used for parking, and the main building was occupied by Morris Brothers Office Supplies and E uipment. The County of San Joaquin appears to have purchased the Site in the late 1980s. The southern adjoining property is the location of Stallworth Auto Sales(602 N. California St.), a former retail fueling facility with documented soil and groundwater contamination. Groundwater gradient directions measured at this location have been historically northeasterly to easterly, and the depth to groundwater has varied between 26 and 35 feet below ground surface (bgs). Groundwater beneath the Site is likely impacted by petroleum ydrocarbons. Groundwater contaminants from Stallworth Auto Sales include: benzene, toluene, ethyl benzene, and total xylenes (BTEX); the fuel oxygenates 1,2- dichloroethane (1,2-DCA) and tertiary-amyl methyl ether (TAME); total petroleum hydrocarbons quantified as gasoline(TPH-G); and total petroleum hydrocarbons quantified as diesel (TPH-D). On May 5, 2011, Condor conducted a subsurface investigation to evaluate potential soil contamination, and to determine whether a UST was present. At approximately 3.4 feet below ground surface (bgs), a metal object was confirmed to be present near the vent pipe, measuring approximately four feet in diameter (based on magnetic response). Four continuous core borings were advanced in the vicinity of the UST to 30 feet bgs (Figure 2, Ap endix A). Contaminated soil was observed in three of the four borings. Fifteen soil samples were collected for laboratory analysis and submitted under chain-of-custody procedures to Argon Laboratories in Ceres, California. The analytical results indicated that subsurface i A CONDOF