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4 <br /> g HORIZON ENVIRONMENTAL INC. <br /> Specialists in Site Assessment,Remedial Testing,Design and Operation <br /> July 30, 1995 <br /> Mr. Larry D. Williams <br /> City of Stockton Department of Municipal Utilities <br /> Environmental Control Section <br /> 2500 Navy Drive <br /> Stockton, California 95206 <br /> Subject: Request for Temporary Discharge Permit to the Sanitary Sewer. <br /> Beacon Station No. 474, 3440 East Main Street, Stockton, California. <br /> Mr. Williams: <br /> At the request of Ultramar Inc. (Ultramar), Horizon Environmental Inc. (Horizon) is <br /> requesting a Temporary Discharge Permit to the Sanitary Sewer from the City of Stockton <br /> Department of Municipal Utilities-Environmental Control Section(CSDMU)for the subject <br /> site. This letter includes a discussion of Horizons proposed activities at this site including <br /> a description of the activities to be performed, site location (see attached Site Plan), <br /> analytical data on the raw water to be discharged, estimated flow rate of discharge water, <br /> estimated total volume of water to be discharged, and proposed startup date. A brief <br /> discussion of these items follows. <br /> Proposed activities consist of performing a 24 hour groundwater pumping test on well MW-2 <br /> to further define aquifer characteristics at the site. During the pumping test, groundwater <br /> will be extracted from the well using a groundwater pump, passed through a flow totalizer <br /> and two 55-gallon activated carbon canisters before being discharged to the sanitary sewer <br /> through a temporary onsite connection. The pretreatment of the extracted water through <br /> activated carbon is to prevent discharge of petroleum hydrocarbons to the sanitary sewer at <br /> concentrations higher then those stated in the Health and Sanitation Code you sent Horizon. <br /> Based on laboratory analysis of water samples collected from well MW-2, we anticipate that <br /> the raw water discharge will not contain petroleum hydrocarbon concentrations greater than <br /> those recently reported from the well (see attached Table 2). The recently reported <br /> concentrations of petroleum hydrocarbons from well MW-2 are 49,000 parts per billion <br /> (ppb) of total petroleum hydrocarbons as gasoline (TPHg), 22,000 ppb for benzene (B), <br /> 1,300 ppb for toluene (T), 280 ppb for ethylbenzene (E), and 1,900 ppb for total xylenes <br /> (X). These reported concentrations of BTEX are higher than the maximum allowable levels <br /> 4.57 parts per million (ppm) Total Toxic Organics for discharge stated in the Health and <br /> Sanitation Code. During the pumping test, water samples will be collected from the <br /> discharge to the sanitary sewer to verify that the hydrocarbon concentrations in the <br /> discharged water are within the maximum discharge limits set up by the CSDMU. These <br /> water samples will be collected after the carbon pretreatment and prior to the discharge point <br /> to the sanitary sewer, and submitted to a State certified laboratory for analysis. The water <br /> 5011 Golden Foothill Parkway,Suite 7 • EI Dorado Hills,CA 95762 • (916)939-2170 • FAX(916)939-2172 <br /> P.O. Box 5283 • Bakersfield,CA 93388 • (805)589-8389 • FAX(805)589-1456 <br />