SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

MEMORANDUM CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION 3443 Routier Road, Suite A Phone: (916)255-3000 Sacramento, CA 95827-3098 CALNET: 8-494-3000 TO: Wendy L. Cohen FROM: David E. Jenldns Senior Engineer Associate Engineering Geologist DATE: 23 September 1993 SIGNATURE: �r SUBJECT: STATUS OF CHEVRON PIPELINE SPILL, TRACY ORCHARD SITE, CORRAL HOLLOW AND GRANT LINE ROADS, TRACY, SAN JOAQUIN COUNTY This site is near the intersection of Grant Line and Corral Hollow Roads in Tracy (see Figure 1) and is adjacent to the Chevron gasoline diesel fuel product pipeline. The southern edge of the Kuden property was the site of a leak in the east-west trending pipeline (see Figure 2). The pipeline leak occurred in April 1987 and was the result of a puncture that occurred during the installation of three shallow (about 25 feet deep) dewatering wells that were drilled along the pipeline route in preparation for the installation of municipal utilities. According to a June 1987 report to Chevron by Dames and Moore (not in our files), approximately 870 barrels (36,540 gallons) of unleaded premium gasoline and diesel fuel were released into surrounding soils as a result of the puncture. Chevron estimated that about 90% of the spilled fuel consisted of gasoline and about 840 barrels were removed. Approximately 100 cubic yards of obviously-contaminated soil were excavated and removed. Subsequently, Dames and Moore installed ground water monitoring wells (MW-1 through MW-3) outside the estimated area of the spill. Ground water is about 10 feet below ground surface with a flow direction to the northeast. On 11 May 1989, Western Geologic Resources (WGR) collected ground water samples from MW-1 through MW-3, three dewatering wells designated DW-1 through DW-3 and one domestic well SW-2. Ground water samples from MW-3 and DW-3 were nondetectable for all compounds analyzed. Samples from DW-1, near the western extent of the spill area, contained total purgeable petroleum hydrocarbons (TPPH) at a concentration of 1,200 ppb. Other hydrocarbons also were detected, including up to 410 ppb benzene. Samples from wells MW-1, MW-2 and SW-2 contained oil and grease. In early 1991, WGR drilled soil boring B-1 through B-5 and converted them to monitoring wells MW-4 through MW-8. Soil samples from B-3, B-4 and B-5 contained up to 1,300 ppm TPPH, 15 ppm benzene, 73 ppm toluene, 28 ppm ethylbenzene and 140 ppm total xylenes (see Table 1). Ground water samples from MW-4 through MW-8 contained up to 120,000 ppb TPPH, 16,000 ppb benzene, 18,000 ppb toluene, 3,700 ppb ethylbenzene, and 18,000 ppb total xylenes (see Table 2). M