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Mr. Mark Dockum Page 2 27 October 1989 <br /> proposing 1 ppm as a cleanup level as discussed in the 14 July 1989 <br /> Preliminary Site Investigation Report (page 7, last paragraph) . As noted in <br /> the Report, the TTLC is not an action level ; however, the TTLC level of 1 ppm <br /> is often proposed as cleanup goal . A more appropriate method of setting goals <br /> is to consider potential health effects, routes of exposure, and probable <br /> attenuation. Such a process results in a site specific level that usually <br /> considers current and potential site use. By applying such a process to the <br /> Cal-Farm Supply site, you may be able to justify the proposed 1 ppm level . <br /> Until the site is fully characterized, I cannot validate the 1 ppm level as <br /> adequate to protect water quality, but I expect that it will be acceptable. <br /> Likewise, other pesticide residues at the site should be reviewed and cleanup <br /> levels determined. The process of calculating cleanup levels based on <br /> toxicities relative to the TTLC for DDT does not result in satisfactory goals <br /> because no consideration is given to relative mobility and appropriate <br /> toxicity (the TTLC for DDT was based on cumulative toxicity to fish) . Based on <br /> my review of the pesticide levels determined to date, I do not anticipate that <br /> any other pesticide at the site will displace DDT as the focus for cleanup <br /> activities (i .e. , if soils are remediated to address concerns for DDT, no <br /> additional soil remediation will be necessary for other pesticides) . <br /> Task 5 is disposal of soils containing DDT. Whereas DDT is a "soft-hammer" <br /> land ban waste, it will be necessary to demonstrate that no treatment process <br /> is available and that landfill disposal is therefore appropriate. The approved <br /> treatment process for organochlorine pesticides is incineration, but there is <br /> currently no incineration capacity in California for soils with DDT residues. <br /> Bioremediation is an alternative treatment process, but is only in the <br /> experimental stage for DDT. Consequently, it appears that with the appropriate <br /> documentation you will be able to dispose of the soil at a Class 1 landfill . <br /> Please contact me at 361-5703 if you have any questions regarding my comments. <br /> John L. Menke <br /> Agricultural Regulatory Unit <br /> JLM: <br /> Enclosures - 2 <br /> cc: Ms. Diane Hinson, San Joaquin Local Health District, Stockton <br />