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Page 4 • • <br /> Concert #7 <br /> We still don' t have any values for the aquifer parameters in the shallow <br /> water bearing zone(s) , the zone which appear to have been impacted from <br /> past waste disposal practices. The values of transmissivity and the <br /> storage coefficient presented in the HAR were only estimates, based on <br /> lithology. These values need to be confirmed, before the HAR is <br /> complete. A pumping test, using one of the shallow wells may help <br /> define if wells MW-1 through MW-5 are screened in different zones. <br /> Also, more reliable data can be collected since drawdown measurements <br /> will be taken in observation wells in the same zone, and not just the <br /> pumped well . <br /> Answer #7 <br /> Section 25208.13. (f) . (3) of the California Toxic Pits Cleanup Act <br /> requires "an estimate of the transmissivity, permiability, and storage <br /> coefficient We have provided these estimates based upon <br /> observed lithology. Another pump test could provide the basis for <br /> refined estimates, but we do not propose another pump test because the <br /> tests are very expensive and the results would have very little value, <br /> especially in this situation where the source of contamination has been <br /> removed and the extent of contamination is very slight and does not <br /> appear to represent any threat to regional groundwater quality. I <br /> propose instead to complete the closure of the surface impoundment <br /> (after approval by the California DHS and RWQCB) and continue to monitor <br /> according to the June 13, 1990 monitoring order from the RWQCB. <br /> Concern #8 <br /> If another pumping test is performed, static water levels in all wells <br /> should be established the day before the test, to monitor any <br /> fluctuations in the water levels prior to pumping. Recovery data should <br /> be collected until the values don' t change significantly over a three <br /> hour period. All wells should be monitored at regular intervals. A <br /> step-drawdown test should be conducted before the test is run to <br /> establish an appropriate flow-rate. The flow-rate should be large <br /> enough to see significant drawdown in the other wells in the same zone. <br /> Answer #8 <br /> If another pumping test is performed, we will consult with you <br /> concerning the test parameters prior to conducting the test. <br />