Laserfiche WebLink
F <br /> STATE OF CALIFORNIA `el � PETE WILSON, Governor <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD— <br /> CENTRAL VALLEY REGION <br /> 3443 ROUTIER ROAD, SUITE A s <br /> SACRAMENTO, CA 95827-3098 <br /> PHONE: (916) 361-5600 <br /> FAX: (916) 361-5686 <br /> 0CT03171 <br /> 2 October 1991 Y <br /> M$. Mary Meays <br /> San Joaquin County Public Health Services <br /> P.O. Box 2009 <br /> Stockton, CA 95201 <br /> GENSTAR-WESTERN STONE PRODUCTS, 8181 EAST 11TH STREET, TRACY, SAN JOAQUIN COUNTY <br /> I have reviewed our file for 8181 East 11th Street in Tracy. In 1988, even <br /> though contaminated soil appeared to have been removed, water in the former tank <br /> excavation contained 110 ppm diesel and 42 ppb benzene. Monitoring well MW-4 was <br /> installed in May 1990. The boring log indicated that a soil sample collected at <br /> 5.5 feet contained 5.8 ppb and 2500 ppb TPHd. A ground water sample collected <br /> from MW-4 in May 1990 contained 1000 ppb TPHd and 8 ppb benzene. Other than <br /> extremely low levels of toluene, ethylbenzene, and xylenes, ground water samples <br /> from the four monitoring wells have contained non-detectable levels of <br /> contamination since October 1990. <br /> Our file contains no original reports or correspondence regarding the initial <br /> investigation/excavation in 1988. The file lacks any explanation for the <br /> contamination in the water sample taken from the pit or the contamination in the <br /> initial ground water sample from MW-4. WaterWork requests closure based on the <br /> lack of contaminated ground water samples since October 1990. However, some soil <br /> contamination remains in place as evidenced by the boring log for MW-4 and, it <br /> is possible, that ground water contamination exists west of the former tank pit. <br /> To proceed toward closure of this site I recommend one of the following options: <br /> 1 . Install several borings through and around (within 10 feet) the former <br /> tank pit, including west of the pit, collect soil samples for analysis <br /> every 2.5 feet to ground water, analyze soil and ground water samples for <br /> BTEX and TPHd, and be prepared to install monitoring wells in the tank pit <br /> and west of the tank pit if ground water appears to be contaminated. <br /> 2. Install a monitoring well in the former tank pit or adjacent to the west <br /> side of the tank pit, collect soil samples for analysis every 2.5 feet to <br /> ground water, and analyze soil and ground water samples for BTEX and TPHd. <br /> 3. Utilize a cone penetrometer device to collect soil and ground water <br /> samples as recommended above. <br />