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MEMORANDUM CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION ,143 loutfer Road 5uile 1 Phone (916) ;000 lacrainento C 1 95827-?098 C 1UNE;T 8-191- WO a TO Gordon L Boggs FROM Elizabeth A Thaver UGT Program Coordinator Associate Engineer DATE 9 December 1994 SIGNATURE S" �,t-C� Ll t SUBJECT REVISED MONITORING AND REPORTING PROGRAM, GEWEKE, .16 SOUTH CHEROKEE LANE, LODI, SAN JOAQ UIN COUNTY I Geweke submitted the quarterly report on 20 October 1994 as required in C&A No 93-701 The I report contained the first analytical results from the site after full-scale inoculation, which occurred on 16 August 1994 On 12 October 1994, the draft Revised Monitoring and Reporting Program (RMRP) was sent out for comment and on 31 October 1994, Geweke submitted their suggested changes by fax The following comments on the quarterly report and Geweke's suggested changes are reflected in the final RMRP Comments on Ground Water Contamination Geweke had previously requested that lead and EDB analyses be deleted from the ground water monitoring You and I agreed, and Geweke dropped them from future monitoring However, on review of the recent quarterly report, MW14 has had consistent EDB contamination Therefore, EDB monitoring of MW14 should be reinstated ' Lead was detected on several occasions, at concentrations below the MCL of 50 µg/l, in a number of wells The highest concentration was 21 µg/l I recommend that lead be dropped from monitoring program DCA has consistently been detected in EW1, MW13, and MW14 and has been detected on several ' occasions in MW7, MW8, and MW9 Chloroform was recently detected in MW7, MW14, and EW1 Geweke requested to delete monitoring of halogenates solvents from wells MW6, MW10, MW11, and MW12 because none has never been detected in those wells I concur with MW6 and I MW10 because they are upgradient MW11 and MW12 are both downgradient I think at least one of these wells should continue to be monitored, I recommend MW12 HVOC's will continue to be monitored in the other monitoring wells IIt appears that the plume may be spreading Concentrations in MW6, upgradient, have increased for the last 3 quarters, from 80 to 1100 ppb TPHg and MW6 had benzene, at 22 ppb, for the first time MW10, a crossgradient well, has shown contamination for the last 4 quarters Previously it had several quarters of ND MW11, downgradient, has also had contamination for the last 4 quarters Previously it had several quarters of ND Ground water extraction for plume control appears necessary