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Rockcastle Company, Grassy Creek Mine Adequacy Responeses ' 1 • ADEQUACY RESPONSES TO 11/22/91 CMLRD COMMENTS JANUARY, 1992 METHODOLOGY CONCERNS A) The use of a CN of 47 far undisturbed sagebrush community is not justified by either the hydrologic soil classifications or the amount of cover found in the baseline studies. Resnonse: Rockcastle concurs with the Division. The hydrologic calculations for Pond 4 and associated ditches which erroneously utilized a CN of 47 (10/16/91 Submittal) have been superseded by the revised calculations subsequently submitted in November, 1991. B) The 1983 copy of 'Soils of Colorado" lots the soil erodability value for the tap 12" of Rockcastle soils as follows: Coutis Fine Sandy Loam .20 Winevada - Splitro Complex .41/.18 Wmevada Fine Sandy Loam .41 Skylick .32 Mr. Nettleton has indicated in telephone conversations that the Rockcastle use of 0.24 is based on the Routs County SCS revision of their soil erodability values. The Division needs to have published verification of these values if the consultant intends to use them with mty frequency. • Response: Current SCS soil erodability values reflecting 1987 revisions were previously provided at the Division's request. A copy of the SCS information accompanies these responses for the Division' use and reference. C) The reclamation seed mix differed slightly from the proposed seed mix in that a number of forts were dropped from the list and an extraordinarily large quantity of winter rye was added. It was noted that the forts which were dropped had a comparatively higher cost. Winter rye was apparently drill-seeded at a rate of 27 pls/acre while all other species combined were applied at 18 pls/acre. Winter rye can be a competitive threat to the establishment of a diversified stand of perennials. Staff vegetation specialists suggest that the use of this quantity of winter rye is marginally acceptable without employment of haying prior to the selling of seeds. Response: Reclamation seeding was consistent with the proposed permanent reclamation seed mixture as defined by Table 6, Seed Mix #3 -Primary Reclamation, of the Rockcastle permit with [be exceptions of 0.5 lbs pls/acre each of western yazrow and silver lupine. Seeding rates for the other forts noted on Table 6 aze specified as "Trace" since these species aze commonly present in small quantities in the seed mixtures distributed in this azea. Miscellaneous trace components aze identified in the seed analysis as "crop" since they aze a relatively small percentage of the total and `aze typically undesignated relative to species. Yazrow was not included in the mix due to limited local availability, lupine was excluded due to potential livestock toxicity, and winter rye was added as a mulch crop to achieve rapid vegetative establishment, protecting available topsoil resources until other species can become well established. ~J ACZ Inc. • P.O. Box 774018 ' Steambcat Springs, Colorado 80477 * (303)8736260