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• <br /> REMEDIAL ALTERNATIVES <br /> - 2 - <br /> My specific comments are listed for each section of the report, as follows: <br /> Executive Summa <br /> 1. The document states that the shallow groundwater contains up to 44 µg/] 1,2-DCP. <br /> two significantly higher concentrations have been detected: in to 4 MW-2 had 160 <br /> in 1995, MW-6 had 88 Actually, <br /> k g/l' k g/I, while <br /> 2. The "basic risk analysis" was not conducted per the Board's guidance for health risk assessments. <br /> A copy of the guidance memo is attached. In addition, there appears to be a basic <br /> misunderstanding of the Board's policy regarding sources of drinking <br /> Basin Plan, except under specific circumstances, all groundwaters are to be protected as existing <br /> or potential sources of municipal or domestic water supply. <br /> water. As stated in the <br /> PP Y• <br /> 3. The report contains an outdated and inaccurate water quality criterion for 1,2-DCP. As listed in <br /> staff report A Compilation of Water Quality Goals (July 1995; updated April 1996 <br /> criteria have been published for 1,2-DCP: <br /> ), the following <br /> California Primary MCL: <br /> USEPA Primary MCL: 5 p g/l <br /> USEPA MCL Goal: 5 µg/1 <br /> Calif Recommended Public Health Level (proposed): zero <br /> USEPA Health Advisory (for toxicity other than cancer risk): 5 lug/l <br /> Cal/EPA Cancer Potency Factor (1-in-a-million cancer risk)) 90 0 56 9/1 (10-day) <br /> USEPA IRIS (1-in-a-million cancer risk) k8/l <br /> USEPA Health Advisory (probably human carcinogen) 0.5 t`g/1 <br /> 1.O In_ trod 0.5 µgIl <br /> I. The maximum listed concentration of 1,2-DCP is in error. <br /> 2. Site investigations have shown that the nitrates and 1,2-DCP in the groundwater are due to the <br /> disposal of waste products into the oil-water separator and three dry wells, as well as the disposal <br /> of rinsewater to the evaporation ponds. <br /> 2.4 Groundwater Chemistry <br /> I think it is important to relate the chemicals that have been found in the groundwater to regulatory <br /> limits, as this shows whether there is a basis for further environmental work. The report does not do <br /> this, so I have summarized the information in the following table. <br />