SITE INFORMATION AND CORRESPONDENCE_1998-2000

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L. Turkatte � • EAI Project No. 1232 October 23, 2000 Page 2 (pumped) principally only during the months of May through October at an average rate of 600 gallons per minute (gpm). Ground water from the RIW was used to irrigate portions of Delta College's campus. Unocal and Wards formerly had underground storage tanks (USTs) on their sites at 5606 Pacific Avenue and 5400 Pacific Avenue, respectively (see Figure 1). Ground water monitoring data for the Unocal and Wards sites show that pumping of the RIW influences and changes the natural direction of ground water flow in the area from easterly, to towards the RIW. The San Joaquin County Public Health Services, Environmental Health Division codes for the Unocal and Wards sites are: Site Name Site Address Site Code Unocal 5606 Pacific Avenue 2162 Wards 5400 Pacific Avenue 2163 Sampling of the RIW by Unocal and/or Wards for dissolved petroleum constituents began in 1997 and continued through June 15, 2000. In August 2000, Delta College students and staff reportedly complained of a gasoline odor from the water derived from the RIW. As requested by the RWQCB, the RIW was taken out of service as of 6:00 AM August 22, 2000, and may not be put back into use without prior RWQCB approval. 1.0 TEST BORING The RWQCB has directed that a long-term irrigation water source that meets the existing design capacity of the impacted RIW, be provided to Delta College. The City of Stockton does not have the ability (excess capacity) to provide this water, and therefore, a New Irrigation Well is required. Since the existing RIW is slotted at various depths between 40 feet bgs and 322 feet bgs, and the New Irrigation Well pursuant to San Joaquin County guidelines can not be slotted at depths shallower than 200 feet bgs, a test boring is required to determine the construction details for the New Imgation Well, in order to ensure that the same volume of water supplied by the RIW taken out of service, will be supplied by the New Irrigation Well. A test boring six-inches in diameter is proposed to a depth of at least 400 feet bgs at the proposed location of the New Irrigation Well (see Figure 1). The test boring will be E-logged and water samples will be collected for analytical testing from potential aquifers bottom to top. These water samples will be selectively analytically tested for chemical constituents, i.e., TPH-G by modified EPA Method 8015 and VOCs including fuel oxygenates by EPA Method 8260B, and for the following general irrigation parameters, carbonate, bicarbonate, chloride, sulfate, nitrate, calcium, magnesium, sodium, electrical conductivity, pH and boron. Soil samples also will be collected for sieve analysis. ENVIRONMENTAL AUDIT, INC.