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ti i <br />~.~ <br />iii iiiiiiiiniuiii <br />STATE OF COLUI~UU <br />DIVISION OF MINERALS AND GEOLOGY <br />Depanmenl °( Nalwal Resources <br />1313 Sherman 51 , Koom ? 15 <br />Denver, Colorado 80?03 <br />Phone: 13031 866 1567 <br />FAY: pOJ) BJ2-8106 <br />MEMORANDUM <br />November 23,1998 <br />TO: File SL-Ol, Phase II Bond Release <br />of Permit No. C-8~1/-010, TQrapper Mining Inc. <br />~'tLf /S ~.~.L~+ <br />FROM: Tom Kald~bach, Environmental Protection Specialist <br />~~~~~ <br />DEPARTMENT OF <br />NATURAL <br />RESOURCES <br />Rov Romer <br />Guvrrwr <br />lames 5 Lochhead <br />E~PCUIrve Direclor <br />htichacl B Lnng <br />Divi,ion Direclor <br />RE: Review of Trapper's submittal with letter dated June 17, 1998 of SEDCAD+ <br />runs for demonstrating that post-mining TSS yields from bond release <br />parcels do not exceed pre-mining yields <br />This memo explains the results of my review of the above-referenced sedimentology <br />demonstration. <br />1. Trapper's selection ofpost-mining CN from SCS Figures S-3 and S-4. Tables 1 and 2, <br />below, summarize the Division's assessment of the reasonableness of the critena that Trapper <br />chose in the two SCS figures S-3 and S-4. The Division considers Trapper's selections of <br />criteria are valid for Figure S-4, but are not valid for Figure S-3. <br />Table 1 -Trapper's selection of criteria in Figure S-3 (SCS TR-55, 1977) <br />Criteria category Criteria Trapper <br />selected as matching <br />all of its bond release <br />blocks Reasonableness of Trapper's selection <br />Cover type (sage- Unreasonable because bond release <br /> blocks are dominated by herbaceous <br />grass juniper-grass, <br />oak-aspen, Sage-grass species with only scattered shrubs <br />herbaceous) (woody shrubs comprise no more than a <br /> few percent of total cover in all blocks). <br />Cover density (0 - Reasonable because acreage-weighted <br />" <br />" <br />8t)%) 75% average <br />allowable cover <br />on bond <br /> release blocks is 77%. <br />