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<br /> <br />Mr. Dick Gamewell <br />June 22, 1982 <br />Page - Nine - <br /> <br />Response to Comment No. 3 - Cotter presently obtains Denver Water Board <br />flow data from gaging stations located in Ralston Creek downstream from <br />the ore sorter, and it collects flow data at the water treatment ~~lant. <br />Accordingly, Cotter has available the data that are necessary to ~:omply <br />with this recommendation. <br />Comment No. 4 - "Using the entire watershed for estimating runoff <br />would provide a dilution factor for Ralston Creek at the point whE~re <br />it enters Ralston Reservoir. This particular dilution calculation <br />assumes no other sources of Ra or U and also assumes background iri the <br />stream to be zero." <br />Response to Conment No. 4 - No response required. <br />Comment No. 5 - "The simulation on page 2-6 (4) appears to be valid. It <br />is not unreasonable to expect concentrations of a constituent to decrease <br />with increased runoff during a storm event." <br />Response to Comment No. 5 - No response required. <br />Comment No. 6 - "Cotters flood plain delineation does not appear t.o be <br />entirely accurate in both Figure 2.2-1 and on the facility site map. <br />In Figure 2.2-1 discharge appears to decrease in a downstream direction <br />which is unlikely and the segment at the ore sorter has the smallest <br />discharge. On the facility site map, the flood plain boundaries appear <br />to be incorrectly drawn in the area of the sedimentation ponds. the <br />flood plain boundaries on each side of the stream are not at the same <br />elevation." <br />Response to Comment No. 6 - Since the date of this comment, Cotter and <br />its consultants prepared a revised flood plain analysis which iias been <br />reviewed and approved by the Water Quality Control Division and the <br />Radiation Control Division of the Colorado Department of Health, the <br />Colorado Water Conservation Board, the Denver Urban Drainage and Flood <br />Control District and the Jefferson County Planning and Zoning Depart- <br />ment. The water treatment plant and ore sorter will be outside the <br />100-year flood plain. <br />Coimnent No. 7 - "Concerning containment for the thickener tank, the <br />permittee may want to place a berm around the downslope side of the <br />treatment building and the sedimentation ponds to prevent spills from <br />entering the ponds and discharging to the stream." <br />Response to Conmient No. 7 - It is presently planned that if that water <br />treatment plant functions as designed, Cotter will construct an <br />