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SOFA Environmental Technology Inc _ November 7, 1994 ' Mr Michael Infurna Senior REHS, Site Mitigation Unit Environmental Health Division ' Public Health Services San Joaquin County 445 N San Joaquin Street Stockton, CA 95201-0388 1 RE: U-HAUL CENTER # 709-50 �/ 2701 N. WILSON WAY, STOCKTON, CALIFORNIA DD ! - SOTA'S PROJECT NO. 94HWO21 7� /Opx ' Dear Mr Infurna SOTA Environmental Technology Inc (SOTA) is pleased to submit the following ' Quarterly Groundwater Monitoring Report for your review This report documents the groundwater sampling program that was conducted on September 28, 29, and 30, 1994 at the subject site Figure I is the site plot plan showing the locations of the wells SOTA's engineer measured the depth to groundwater at all six monitoring wells. MW-1, MW-2, MW-3, MW-4, MW-5, and MW-6 on September 28, 1994 The depth to the water level and the corresponding surface elevations, with respect to mean sea level, are presented in Table 1 ' SOTA's engineer met with Mr Michael Infurna of San Joaquin County- Environmental Health Division on September 29, 1994 The protocol to be followed in the purging and sampling operations were demonstrated to him ' Due to massive amounts of silt entrapped in the wells, purging could not be accomplished at that time Subsequently a replacement pump was obtained to carry out the purging The sampling program was conducted as described below A minimum of 4 well volumes, which was calculated to be 12 gallons, was required to be purged from each of the six wells During purging operations the temperature pH, and ' conductivity were measured with the water flowing through a continuous flow chamber The pumping was carried on until the temperature, pH, and conductivity values stabilised within at least 5% of previous readings MW-1, MW-2, MW-3, MW-4, MW-5, and MW-6 were purged of 50, 35, 50, 25, 18, and 15 gallons of water respectively using a 2-inch submersible pump Copies of the field observation which includes temperature, pH, and conductivity values are enclosed in Appendix-A Proper decontamination procedures which ' included flushing the pump and hose with soap water, followed by two rounds of clean tap water, with a final rinse using deioniied water were employed The purged water is stored in 55-gallon DOT approved drums which have been labeled and stored on-site for subsequent treatment/disposal Adequate time