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ATTACHMENT <br /> EPA COMMENTS ON THE <br /> FINAL WELL MONITORING PROGRAM QUARTERLY MONITORING REPORT <br /> APRIL 1993 SAMPLING ROUND <br /> (AUGUST 1993) <br /> The following addresses comments to which DDRW-Tracy did not adequately respond in this <br /> semiannual report. The following comment numbers from EPA's letter (dated June 18, 1993) <br /> to DDRW-Tracy regarding the January 1993 Quarterly Monitoring Report. <br /> Previous EPA comment No. 2 stated <br /> "Section 1.2.1.2 summarizes that trichloroethene (TCE) and tetrachloroethene (PCE) <br /> have been detected above maximum contaminant levels (MCLs) in the Upper Tulare <br /> formation beneath the site. Please make mention in this background section that <br /> additional contaminants have consistently been detected in groundwater above <br /> background levels and/or above state of California action levels. These contaminants <br /> are dieldrin, arsenic, chromium, and manganese." <br /> However, Section 1.2 on Background states that "based on the results from previous <br /> investigations, it was determined that TCE and PCE were present in the uppermost <br /> hydrostratigraphic unit (Upper Tulare Formation) beneath the site at concentrations above the <br /> U.S. Environmental Protection Agency (EPA) established Maximum Contaminant Levels <br /> (MCLS) of 5 micrograms per liter (pg/L) for each compound." No response is given in this <br /> section to EPA's Comment No. 2. <br /> In Table 2 for monitoring well LM3 for the last two monitoring rounds, average <br /> concentrations of the major carcinogens detected result in these approximate excess cancer <br /> rates per million exposed population, as calculated from EPA's August 1993 Table of <br /> preliminary remediation goals (PRGs): 130 for total arsenic, 61 for dieldrin, 7 for <br /> tetrachloroethene (PCE), 6 for trichloroethene (TCE), and 2 for chlordane. The industrial <br /> wastepond [IWP], located hydraulically upgradient from well LM3, appears to be a major <br /> source of contamination from arsenic, dieldrin, and now chlordane as well. <br /> Corrective Action: Please state that dieldrin, arsenic, chromium, and manganese have <br /> consistently been detected in groundwater above background levels and/or above state of <br /> California action levels (see attached Tables 2, 3, and 4.) These potential contaminants must <br /> be adequately addressed by DDRW-Tracy in the site-wide comprehensive remedial <br /> investigation/feasibility study (RI/FS). <br /> Section 1.1.0.2 states the following objectives: <br /> 1/3 <br />