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iii iiiiiiiiiiiuiii <br />999 <br />STATE OF COLORADO <br />DIVISION OF A1INERALS AND GEOLOGY <br />~"I' dllu'pI nl N,IIUr,II RPSUUfCBs <br />I ; ; tihrl ntdn 'il., Roum 71 $ <br />IJ~.•nvcr, (:ul ntadu OU2U5 <br />I'In tn~': I {I) ~1 "•66-156; <br />In~~r.n 11 +; 11-alno <br />Internnl Memo <br />DIVISION OF <br />MINERALS <br />GEOLOGY <br />RECLAMATION <br />MINING•SA FETY <br /> Bill Owen. <br /> Gnccrnnr <br /> <br />TO: <br />Larry Routten Gn~C E NAJ~.ber <br />E~ecw"•. Dnei,ur <br />FROM: Sandy Brown Michael B. Long; <br /> <br />DATE: <br />April 9, 1999 Drc~.htn DIIICIU! <br />RE: Seneca II-W, PR-2 Adequacy <br /> Draft Narrative Regazding Potential Material Damage <br />Assuming a worst case scenazio the postmining water quality in Hubberson Gulch <br />projected by SCC is 2.0 mmhos/cm. (SB: Confirm this number with Mike Boulay and <br />Kent Gorham.) <br />SCC has presented updated information regarding the pastures that aze irrigated by <br />Hubberson Gulch. After talking with the landowner, SCC detetmined that there are two <br />pastures, with different seed mixes. The total combined area is 26 acres. A herd of 300 <br />head of cattle graze on these Fields. DMG has reviewed the information and data <br />provided by SCC. During the course of the review several items of concern were noted. <br />SCC has made the assumption that the seed mix as planted represents the crops currently <br />growing in each pasture. SCC has further assumed that the upper and lower pasture each <br />cover half of the 26 acre`total pasture area. The DMG has some concerns regazding these <br />assumptions. <br />The seed mix does not accurately represent the actual species production growing in the <br />pastures currently. Using the seed mix composition provided by SCC the data from the <br />upper pasture indicates it is nearing or exceeding potentially significant levels of yield <br />reduction as seen on the attached table. In order to accurately represent the pasture <br />productivity and potential yield reductions, the productivity of each pasture by species is <br />needed. Pasture specitic productivity data by species should be used to calculate potential <br />yield reductions. <br />A description of the pasture management is needed. SCC has averaged the values for <br />each pasture to estimate total projected yield reductions. This is acceptable if both <br />pastures are equal in size and the pasture is managed as one combined pasture. However. <br />the pastures may not be of equal size and in some cases pastures are divided and managed <br />separately. In addition to relative size and use of each pasture, the description of pasture <br />management should include the irrigation practices and seasons of use. <br />