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THE SAN JOAQUIN COMPANY Inc. <br /> 1400 Solano Avenue, No. 12, Albany, California 94706 <br /> t <br /> ' May 23, 1996 <br /> City of Tracy <br /> Department of Public Works <br /> 3900 North Holly <br /> Tracy, CA 95376 <br /> Atn: Mr. Robert Sagaser <br /> ' Dear Mr. Sagaser <br /> Subject: Discharge of Treated Groundwater to the Sanitary Sewer <br /> at 2480 Tracy Boulevard. <br /> ' On April 2, 1996, during excavation work for construction of a new car-wash and <br /> lubrication-service facility, groundwater beneath the property at 2480 Tracy Boulevard, <br /> ' Tracy, California was found to be contaminated by gasoline that has been carried down <br /> the groundwater gradient from the adjacent property at 575 West Grant Line Road. <br /> ' The owner of the 2480 Tracy Boulevard property, Mr. Rudy A. Sanchez, retained The <br /> San Joaquin Company Inc. as consulting engineers to plan and oversee an emergency <br /> remediation program to permit continuation of construction. The remediation work was <br /> ' implemented by Dietz Irrigation, an experienced remediation contractor holding a Class A <br /> General Engineering licence, with Hazardous Waste endorsement, issued by the <br /> California Contractors State License Board. <br /> ' To permit construction of a basement for the new facility, it was necessary to lower the <br /> ' water table by pumping from a sump connected to subsurface dewatering drains. The <br /> contaminated groundwater pumped to the surface was temporarily stored in mobile <br /> 20,000-gallon tanks(Baker tanks). <br /> iAfter obtaining your guidance regarding the water-quality and maximum flow-rate criteria <br /> for discharges to the sanitary sewer, we determined that, by treating the water by passing <br /> ' it through granular activated carbon, it could be safely disposed in that way. <br /> The contaminated groundwater that had been temporarily stored in the 20,000-gallon <br /> Baker tanks was pumped, one tankful at a time, though a pair of 45-gpm (gallons-per- <br /> minute) hydraulic-capacity, series-connected, granular-activated-carbon retorts into a <br /> second array of Baker tanks. The water-treatment system was operated as a batch process <br /> ' so that each tank of treated water could be sampled and the sample analyzed before the <br /> batch was discharged to the sewer. <br /> Telephone:Tracy,California 209-832-2910 Albany,California 510-527-5515 <br />