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Division might ask for more measurements to constrain the degree of sorption within the <br />stratigraphic column. Sorption also cannot be considered on a single parameter basis because <br />sorption sites consumed by one parameter would not be available for other parameters, so it is <br />not conservative to run sorption calculations in the manner they were run. <br />Also, it is not evident that the simulations considered the worst local cases for mine sites in each <br />of the two study areas. We are not familiar enough with the individual ore bodies and their <br />settings relative to the local water table and the river to evaluate each explicitly, but we presume <br />that each site probably rests at a different distance above the local water table, at variable <br />distances from the river, and that the simulation for each of the two groups of ore deposits <br />should be run for that deposit in each group with the least distance between the ore and the <br />water table, as well as for the least lateral distance between the ore body and the river. <br />Because the most recent simulation was run for only one situation, we would ask what <br />conditions apply to the other set of ore deposits. <br />We also question the effects of the less-permeable strata in the stratigraphic succession on the <br />transport of potential contaminants. Intuitively it seems that the siltier and shaleier units would <br />slow the rate of vertical transport, and spread out the contaminant plume. Accepting that <br />assumption, we wonder whether the contaminant plume would spread to, say, a cliff face where <br />it would flow more directly and quickly to the adjacent stream. (We recognize that at least some <br />of the mineralized strata dip away from the adjacent streams, but do they all do so?) The model <br />simulations appear not to account for the effects of what we would presume are the variable <br />transmissivities of each stratigraphic unit. <br />Once we receive a revised report that includes the conditions specified above, Kate and I will <br />provide a definitive review. Meanwhile, the applicant might be encouraged by what appear to <br />be good results for a conservative simulation. <br />If the operator or consultants have any questions, they should please feel free to contact me at <br />303-866-3927 or Kate at 970-259-5861. <br />Cc: Bruce Humphries (via a-mail) <br />Carl Mount (via a-mail) <br />