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Harding Lawson Associates <br /> July 12, 1993 <br /> 10433 003 <br /> Mr. Chuck Kolesar <br /> Shell Oil Company <br /> 511 North Brookhurst Street <br /> P.O. Box 4848 <br /> Anaheim, California 92803 <br /> Deep Monitoring Well Work Plan <br /> Shell Oil Distribution Plant <br /> Stockton, California <br /> Dear Mr. Kolesar: <br /> Harding Lawson Associates (HLA) has prepared this work plan for the installation of a <br /> deep monitoring well at the Shell Oil Company Distribution Plant, 3515 Navy Drive, <br /> Rough and Ready Island, Stockton, California, as agreed in previous correspondence. <br /> This well will be used to monitor and sample the next water-bearing unit beneath the <br /> uppermost aquifer at the site and to evaluate potential vertical migration of <br /> hydrocarbons through the groundwater. <br /> The deep monitoring well, DW-1, will be installed onsite near new shallow <br /> groundwater extraction Well MW-24 (Plate 1). All drilling work will be performed <br /> using a truck-mounted hollow stem auger rig, and will be performed under the <br /> supervision of an HLA geologist. Relatively undisturbed soil samples for lithologic and <br /> chemical analysis will be collected at 5-foot intervals to an approximate depth of <br /> 40 feet. Chemical analyses will only be performed on soil samples collected from the <br /> vadose zone. Soil samples submitted for chemical analyses will be analyzed for total <br /> petroleum hydrocarbons (TPH) calibrated as gasoline and diesel fuel using modified <br /> EPA Test 8015; benzene, toluene, ethylbenzene, and total zylenes (BTEX) using EPA <br /> Test Method 8020; and for total lead using EPA Test Method 7426. The borehole will <br /> be continuously cored from 40 feet to total depth to evaluate the lithologies beneath <br /> the uppermost aquifer at the site. <br /> Lithologic logs of the borings will be prepared using the Unified Soil Classification <br /> System. Prior to drilling, all downhole drilling equipment will be cleaned using a <br /> high-pressure hot water washer (steam cleaner). Soil sampling equipment will also be <br /> cleaned initially with a steam cleaner and cleaned between samples using phosphate- <br /> free soap, and rinsed with clean tap water. All drill cuttings will be retained in labeled <br /> 55-gallon drums and analyzed for petroleum hydrocarbons prior to disposal. <br /> Engineering and 7655 Redmod Boulevard, PO Box 578, Novato, CA 94948 415/8920821 <br /> Environmental Services A SubsO.,nj Harding M,m,wes•cffiees Nurinnwide <br />