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��'t''St"1-191400- <br /> Smote 1 v0 WoodwaAClyde Consultants <br /> Oakland CA 94607-4014 <br /> [415]893-3600 <br /> August 23, 1988 pProaly <br /> 8820101A ;f1 <br /> arra 2 4 1990 <br /> Ms. Diane Hinson ENVINUML-r f AL HEALTH <br /> San Joaquin Local Health District PERMIT/SERVICES <br /> 1601 East Hazelton Avenue <br /> Stockton, CA 95201 <br /> Subject: Supplemental Information for Subsurface Assessment <br /> 1250 N. Wilson Way, Stockton <br /> Dear Ms. Hinson. <br /> Pursuant to your request, this letter has been prepared to supplement <br /> information in our June 8, 1988 proposal to conduct a subsurface <br /> assessment at the Thrifty Oil Co. Service Station 171 located at <br /> 1250 N. Wilson Way in Stockton, California. Specifically, the <br /> information requested includes location of nearby utilities and <br /> buildings , proposed disposal of soil cuttings and well development <br /> water, and methods of drilling and sampling. <br />• The relative locations of public utilities and nearby buildings are <br /> provided on the attached drawings. The utility locations were obtained <br /> from the Stockton Department of Public Works. As shown, the boring <br /> locations comply with the minimum setbacks of 50 feet from any sewer <br /> lines and 10 feet from the property lines. <br /> Methods of drilling and sampling will consist of using a Mobile B-53 or <br /> B-57 hollow-stem auger rig equipped with 10-inch outside diameter, <br /> continuous flight augers. Soil sampling will be conducted at 5-foot <br /> intervals using a 2-inch I.D. modified California sampler containing <br /> four, 4-inch-Tong brass tubes. The sampler will be driven ahead of the <br /> augers using a 140-pound drop hammer. The average blow counts required <br /> to drive the sampler 12 inches will be recorded on the boring logs. <br /> After each sample drive, the sampler is extracted from the boring and <br /> the brass tubes removed. The soil exposed at the ends of each tube will <br /> be examined for stratigraphy and obvious presence of contamination. <br /> These observations will be recorded in the boring logs. In general , the <br /> bottom tube will be sealed at each end with aluminum foil , PVC end caps, <br /> and electrical tape and placed in cool storage until delivered to the --4�'C� <br /> laboratory. The middle tube is then extruded into a Ziplock bag, sealed <br /> and left in the sun for 5 minutes to enhance the volatilization of any <br /> hydrocarbons that may be in the soil . Subsequently, a headspace reading <br /> will be taken from the interior of the bag using an HNU photo-ionization <br /> organic vapor meter. These readings will be recorded on the appended <br /> boring logs as well . <br /> Consulting Engineers Geologists <br /> and Environmental Scientists <br /> Offices in Other Principal Cities _ <br />