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INTEROFFICE MEMORANDUM <br />TO: JANET BINNS <br />FROM: ROB ZUBER <br />SUBJECT: SENECA IIW, SL-05, FINDINGS TEXT FOR SEDIMENTOLOGY <br />DATE: 7/1/2014 <br /> <br />Janet – <br /> <br />I have written the following for the SL-05 findings document. I envision the Sedimentology sub- <br />section being inserted in the OBSERVATIONS AND FINDINGS section. The last part can be <br />placed in your SUMMARY AND CONCLUSIONS. <br /> <br /> <br />Sedimentology <br />In the application for the SL-05 bond release, SCC provided TSS data for five years of discharges <br />from five ponds (006, 009, 015, 016, and 017). This data indicates that average concentrations for <br />all five of the ponds, over the five-year period, did not exceed the monthly exceedance limit of 35 <br />mg/l listed in the Colorado Discharge Permit System (CDPS) permit for Seneca II-W. While this is <br />a comparison of a five-year average to a criterion for a monthly average, it provides a decent measure <br />of the chronic condition of TSS concentrations from the ponds. SCC also provided a comparison of <br />discharge data to the maximum CDPS limit of 70 mg/l, and no exceedances were reported. <br /> <br />While this information was useful, it did not completely meet the requirements of Rule 3.03.1(3)(b), <br />which states that, “No more than sixty percent of the bond shall be released so long as the lands to <br />which the release would be applicable are contributing suspended solids to streamflow or runoff <br />outside the permit area in excess of levels determined on adjacent nonmined area.” Therefore, the <br />Division requested the following from SCC: <br /> <br /> TSS data for Pond 005, since this data was omitted from the original submittal while data for <br />other ponds was submitted. <br /> <br /> TSS data for Sage Creek upstream of points 015 and 009. This data would allow the <br />Division to assess the assertion that TSS concentrations in the creek above the mine are <br />higher than concentrations in discharges. <br /> <br /> To assess sediment loading from the reclamation areas related to SL-05, the Division asked <br />for: <br /> Pond capacities based on survey data. <br />o <br /> An analysis using a predictive model, such as SEDCAD or RUSLE, which <br />o <br />compares the suspended solids generated off the pre mining land or comparable <br />adjacent areas to the bond release area. <br /> <br />