REV13604 - Laserfiche WebLink

Home Browse Search

_ ~ rFile SL-01, Permit No. C81-010 _ Trapper Mining Inc. Table 2 -'Trapper's selection of criteria in Figure S-4 (SCS TR-55, 1977) I (/23/98 Page 2 Criteria category Criteria Trapper Reasonableness of Trapper's selection selected as matching all its bond release blocks Land use (pasture/range, pasture or range Reasonable because bond release blocks meadow, row crops, are rangeland. etc.) Cover treatment or Reasonable based on Trapper's response practice (contoured Contoured in a letter dated November Z, 1998. or not) Reasonable because the acreage-weighted average "allowable cover" for all nine blocks is 77%. "Good" hydrologic condition refers to greater than 75% ground cover (page 2-7 of 1986 TR-55). The Division would not strictly consider that "allowable cover" (rather than total Cover hydrologic herbaceous cover) be used in ranking condition (poor, fair, Good hydrologic condition, but annuals are so or good) abundant at least on A Pit RSA and C Pit RSC that vegetative erosion control on those two blocks could be seriously diminished if most of the annuals on those blocks do not return in a growing season. Overall, though, the nine blocks together would yield sediment equivalent to a "good" hydrologic condition. Reasonable because infiltration rate of B soil is 0.15-0.30 inches per hour. This rate is consistent with pre-mining infiltration Hydrologic soil rates of Trapper's soils estimated by the group (A, B, C, or B Soil Conservation Service under saturated D) conditions as shown in Appendix G, Part III of the permit application and post- mining infiltration rates of Trapper's soils under dry conditions as shown in Table 4.8-14 of permit application. 2. Control Practice (C) factor selected for A Pit RSA and C Pit RSC. Trapper used the "total herbaceous cover" percentage rather than "allowable cover" percentage for picking the post-mining C factor for each bond release block. The use of "total herbaceous" rather than