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Comparing the MCL standards listed in Table 6-5 with the standards listed in the Division's "Material Damage Suspect Levels"r 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 are 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, the RCRA standards do not appear to be listed in this report. In the analyses of possible contamination of surrounding vegetation, reference is made to "minimum phytotoxic levels." These levels are not listed in the study, although there is a reference to USEPA, 1983 on page 5- 16. No information has been submitted that would show if these vegetation toxicity levels are relevant to the vegetation at Trapper. There is a possibility that the NPDES permit will need to be amended to take into account this fly ash. Presently, fl~+ 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. If Trapper wishes to pursue this idea, then Trapper must submit a detailed plan, through the permit revision process, that will ensure that adverse impacts to the hydrologic regime, as well as any other impacts, will not occur. The Division also may require that permitting and mitigation actions, similar to those that are being employed already for ash disposal at the mine site, be used for the haul road fly ash sites. If you have any questions, please call me. Sincerely, (~ D. os ph \Y. Dudash nvironmental Protection Specialist CC: David Berry C:\WP51\TRFLYASH.LET