SITE INFORMATION AND CORRESPONDENCE

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0/LDC Year End Report -3- • 8 June 1990 4. Water levels in monitoring wells MW-1, MW-2, and MW-3 fluctuated from 0. 1 to 0. 16 feet during the test. However, water levels MW-4 and MW-5 did not fluctuate during the test. The following day water levels were measured at two times during the day (four hours apart) to see if ground water fluctuated in the three wells, without pumping MW-6. The water levels in the wells fluctuated 0.04 to 0.05 feet. Are there any outside influences on the wells that could cause these fluctuations? Static water level measurements should have been taken the day before the test, at regular intervals to check for any fluctuations in the wells. 5. Appendix G contains the computed values of transmissivity and the storage coefficient for the water bearing zone encountered by MW-6. The values are reasonable, when compared to literature values for the lithology of the well . However, as stated in Appendix F, none of the other wells are screened in the same water bearing zone as MW-6. How was the storage coefficient calculated, without an observation well? Was the value only an estimate? If so, the rationale behind it should be included. 6. The report claims that three separate aquifers exist within the first one-hundred- twenty-five feet below ground surface at the site. Different aquifers must be both hydraulically and chemically separated from one another. I plotted the results of the minerals analysis performed on the samples that were collected in January 1990 on piper and stiff diagrams (see Figures 1 and 2) . The water in each of the wells appear to have similar chemical characteristics. There is less than two feet of head difference between all of the wells. Some of this is due to the ground water gradient. It seems unlikely that the wells are in three hydraulically separated aquifers, when the difference between heads is so small . We cannot conclude that the water bearing zones encountered by the wells are hydraulically separated from the results of the pumping test, since there were only five data points collected from MW-1 through MW-3, and MW-5. Also, static water level measurements were not collected on the day prior to the test. It has not been demonstrated that the water bearing zones encountered by the wells are chemically and hydraulically separated from one another by either the pumping test or the chemical data. Therefore, although the wells may be screened in different water bearing zones, there is insufficient evidence to conclude that these zones are separate aquifers or how many different zones exist. 7. We still don't have any values for the aquifer parameters in the shallow water bearing zone(s) , the zone which appears to have been impacted from past waste disposal practices. The values of transmissivity and the storage coefficient presented in the HAR were only estimates, based on lithology. These values need to be confirmed, before the HAR is complete. A pumping test, using one of the shallow wells may help define if wells MW-1 through MW-5 are screened in different zones. Also, more reliable data can be collected since drawdown measurements will be taken in observation wells in the same zone, and not just the pumped well . 8. If another pumping test is performed, static water levels in all wells should be established the day before the test, to monitor any fluctuations in the water levels prior to pumping. Recovery data should be collected until the values don't change significantly over a three hour period. All wells should be monitored at reguiar intervals. A step-drawdown test should be conducted before the test is run to establish an appropriate flow-rate. The flow-rate should be large enough to ==_e significant drawdown in the other wells in the same zone. JEM:jm