Laserfiche WebLink
i- <br />MEM0RANDUN4401 <br />CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD • CENTRAL VALLEY REGION <br />3443 Routier Road, Suite A Phone: (916) 255-3000 <br />Sacramento, California 95827-3098 CALNET: 8-494-3000 <br />To: EAT, GLB <br />Underground Tank Unit <br />FiROR WEG <br />Underground Tank Unit <br />DATE: 29 June 1995 SIGNATURE: _ ;+ _ _ An- Liz -67 <br />SUBJECT: REQUEST FOR CLOSURE, CORRIGAN PROPERTY, 620 NORTH SAN JUAN, <br />STOCKTON, SAN JOA QUIN COUNTY <br />Two 1,000 gallon underground storage tanks (USTs), one regular gasoline and one diesel tank, <br />were removed from the site in May 1986. Hydrocarbon contamination of soil and ground water <br />were noted during the tank removal. Initial samples taken from the tank removal showed <br />concentrations of Total Petroleum Hydrocarbons as gasoline (TPHg) and diesel (TPHd), and <br />benzene, toluene, ethylbenzene and xylenes (BTEX) in parts per million (ppm) as follows: <br />Constituent <br />Soil <br />Ground Water <br />TPHg <br />960 <br />450 <br />TPHd <br />2,300 <br />non -detect (ND) <br />B <br />0.9 <br />0.26 <br />T <br />0.98 <br />0.48 <br />X <br />7.9 <br />0.84 <br />The site was overexcavated in December 1993, and approximately 1,400 cubic yards of <br />contaminated soil was removed. Residual hydrocarbons remain in a small lens of soil that extends <br />to an unknown point underneath the existing building on-site. All confirmation samples showed <br />ND except three sidewall samples, which indicated up to .070 ppm benzene, 35 ppm TPHg and <br />430 ppm TPHd, underneath the building. A Contaminant Fate and Transport Evaluation, <br />submitted by Resna, states that approximately 233 cubic yards of soil containing 22.1 pounds (3 <br />gallons) of diesel and 192 cubic yards of soil containing .014 pounds of gasoline (.002 gallons) <br />remain. And due to the clayey soils and location of the remaining impacted soil, no remedial <br />alternatives are thought to be feasible without destroying the building. <br />Three monitoring wells were installed at the site. The ground water flow direction was <br />determined to be to the east-northeast at .0065 ft/ft. Quarterly ground water elevation <br />measurements and ground water sampling were conducted from January 1992 to April 1993. The <br />greatest ground water level fluctuation during that period was approximately 3.5 feet. The wells <br />showed ND concentrations for BTEX, TPHg and TPHd during that period. <br />