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Memorandum - 2 - 8 April 1992 <br /> G. one well , 11D in Figure 3, is directly downgradient of the site, <br /> across the intersection of El Dorado and Channel Streets. If this <br /> well is used frequently it may be influencing the direction of <br /> ground water flow. This well may be threatened or impacted by the <br /> contamination from this site. <br /> H. The pumping tests on MW5 were adequate to observe and record the <br /> impact on MW1, MW2, MW3, and MW4, used as observation wells, and <br /> to calculate transmissivity, storage coefficient, and zone of <br /> influence. The pumping test calculations were used to develop a <br /> proposed ground water extraction and reinjection system: <br /> 1. After completion of the pumping tests, the "recovery of MW5 <br /> was mnnitnred" but no data on the recovery was provided. <br /> This data, if properly presented would have provided <br /> additional information on the aquifer properties. <br /> 2. One or two new extraction wells are proposed. The rationale <br /> for locating the proposed well (s) near the property boundary <br /> rather than in the center of the contamination plume was not <br /> included. <br /> 3. For one new extraction well , the downgradient capture zone <br /> was calculated to be 46 feet, and for two extraction wells, <br /> 90 feet. It was stated that "the primary difference in the <br /> two approaches is the time required to recover the on-site <br /> contamination." Because the downgradient extent of <br /> contamination is unknown, it cannot be known that any <br /> proposed extraction system will be adequate to recover all <br /> off-site contamination. <br /> 4. It was proposed that treated ground water be reinjected <br /> through MW5. The impact of this reinjection on the gradient <br /> and plume was not discussed. <br /> 5. The impact of the down-gradient off-site well on the <br /> gradient and plume was not discussed. <br /> 6. The impact of tidal influences from the Stockton Deep Water <br /> Channel were not addressed though "natural fluctuations" <br /> were observed during static monitoring of some of the <br /> monitoring wells. <br /> II . quarterly reports have not been submitted as per Section 2652(d) of the <br /> Underground Tank Regulations. <br />