Laserfiche WebLink
fJ <br /> Quarterly Summary Report <br /> Fourth Quarter 2001 <br /> Tosco(Former Unocal) Service Station#4409 <br /> 1502 North EI Dorado <br /> Stockton, California <br /> CITY Stockton <br /> COUNTY San Joaquin <br /> BACKGROUND <br /> The site is located on the northeast corner of Harding Way and El Dorado Street to Stockton,California The site is <br /> a former Unocal service station that retailed gasoline and diesel fuel On April 7, 1999,three 10,000-gallon capacity <br /> underground storage tanks(USTs)were removed from the site Two USTs contained gasoline and one contained <br /> diesel fuel Initial remedial activities included source removal of obviously impacted soil to a depth of <br /> approximately 18 feet below ground surface(bgs)beneath the center of the western fuel tank Additional remedial <br /> activities included source removal of obviously impacted soil in the area beneath the former dispenser and product <br /> lines A concrete pad restricted the lateral extent of excavation During excavation of impacted soil,unidentified <br /> fiberglass piping was found Additional excavation and sampling was completed on April 8, 1999 to remove the <br /> unidentified piping Samples were collected from the bottom and side walls of the excavated area Following <br /> removal of the former station canopy, canopy footings and kiosk, additional over-excavation was completed in the <br /> dispenser area Over-excavation was terminated when obviously impacted soil was removed,the structural integrity <br /> of the sidewalk was endangered,or groundwater was encountered Residual hydrocarbons remain in the soil and <br /> groundwater A total of approximately 1,707 tons of soil was transported off-site for disposal at the Forward <br /> Landfill in Manteca, California Four groundwater monitoring wells were installed in December 1999 Vertical <br /> assessment conducted in July 2000 identified soil and groundwater impacts at depths of 60 feet bgs The <br /> SJCPHSIEHD verbally requested a workplan for further delineation of soil and groundwater impacts Three on-site <br /> groundwater monitoring wells were installed in December 2000 The lateral and vertical extent of soil impacts is <br /> generally delineated Deep zone groundwater impacts were identified Three deep zone groundwater monitoring <br /> wells were installed in August and September 2001 <br /> RECENT QUARTER ACTIVITIES <br /> • Conducted groundwater monitoring of shallow and deep wells <br /> • Submitted Quarterly Status Report <br /> IT CORPORA T10N <br /> SAC IN IsacDP120021PRJIPJ$1821822121 2aa doe-021rt 1 <br />