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other is MCL (maximum contaminant level). For example, Table 6-5, on page 6-11, lists TCLP and MCL levels for the Arizona site, both in mg/L. On page 6-10 there is a discussion of the results of Table 6-5. The eight metals listed in the table are RCRA metals so, I assume, all of the regulatory standards used in this study are related to RCRA, and, therefore, are from the EPA. Comparing the MCL standards listed in Table 6-5 with the standards listed in the Division's "Material Damage Suspect Levels", there are some differences. Notably, the MCL for selenium is .5 mg/1, while the Division's standard is .O1 mg/1 for drinking water and .02 mg/1 for agriculture and irrigation. The MCL for arsenic and mercury ape the same as the drinking water standard that the Division uses. The MCL for cadmium and lead are more strict than what the Division uses, for drinking water. The MCL for barium, chromium and silver are not as strict as what the Division uses for drinking water. As far as the other chemical constituents, I do not believe the RCRA standards are listed in this report. In the analyses of possible contamination of surrounding vegetation, reference is made to "minimum phytotoxic levels." I do not know what these levels are, nor are they listed in the study, although there is a reference to USEPA, 1983 on page 5-16. I also do not know if these vegetation toxicity levels are relevant to the vegetation at Trapper. 5. There is a possibility that the NPDES permit will need to be amended to take into account this fly ash. Presently, fly ash is buried in former pits, with surface runoff being diverted around the immediate area. As a haul road subbase, the fly ash may come in contact with surface water and be washed downstream. C:\WP51\TRFLYASH S ~ ~/ ~ /~-a fit: ~' -~ G/y ~ ~2i~ C(vn .?-~e^~ Tn a ~ m..~ ~ ,'L--v+,../! U ~K' ' ~'.'""a~ a_.,_~a ~/v / Vim'.. '/ °1 .vJ J' . ~~ n ~~,} ~. ~ 3 r; n .. ~ ' /~ ' , ,