SITE INFORMATION AND CORRESPONDENCE

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9. This section discusses the organochlorine pesticides that have been detected at DDRW-Tracy. It is stated in this section that no maximum contaminant levels (MCLS) have been established for these compounds. While this is true, it should be noted that the Cal-EPA DTSC has established an action level (AL) for the toxicity of dieldrin at 0. 05 µg/1. EPA has also proposed ALs under 40 CFR Part 264 Subpart S (55 FR 30798, July 27, 1991) for some of these compounds, described as follows: TABLE 1: SUMMARY OF PROPOSED ACTION LEVELS FOR SPECIFIC CONSTITUENTS (µg/1) EPAIPROPOSED DHS ACnON LEVEL 'WCCS C0NSI7TUENT MCL DETEMON LIMIT Chlordane 0.1 0.03 OS Dieldrin - 0.002 0.1 Heptachlor 0.01 0.008 0.1 Heptachlor 0.01 0.004 0.1 Epoxide 1 Effective July 1992 The detection limits chosen by DDRW-Tracy for several constituents were higher than the MCLs established as a water quality goal by the State of California, and higher than the proposed EPA ALS that will become effective in July 1992 . • DDRW-Tracy needs to adopt the more stringent standards in the future sampling rounds to keep pace with regulatory guidelines in the ongoing Remedial Investigation/Feasibility Study (RI/FS) process. 10. The detection limits used in the EPA method 8015 for Total Petroleum Hydrocarbons as diesel (TPH-diesel) were higher than most of the historic positive results for diesel. Historically, from May 1988 to May 1991, TPH-diesel analyses indicated values ranging from 0. 07 to 0.46 mg/1. The detection limits used by DDRW-Tracy in the August 1991 sampling round ranged from 0. 1 to 0. 3 mg/1. This discrepancy could result in a false negative for the TPH- diesel results. • DDRW-Tracy, in consultation with Cal-EPA, should provide for lower detection limits in future analyses. 3 of 7