GENERAL30857 - Laserfiche WebLink

Home Browse Search

photo analysis shows a significant area of suspect AVF; however, color photos submitted by the operator show the potential area of the AVF as closely corresponding to the SCS survey area 08. Based on the data presented by the operator and the lack of test pits in the lower or' ~~ northern portions of area 08, the Division finds that Flume gulch is an AVF-; currently_defined by that area shown on Map`3~ae 0'8--fit should be ~~ note that the operator will not disturb this area because it is outside the current or proposed permit boundary. Additionally, the quality or quantity of water supplying the AVF will not be jeopardized by mining. V (2 .07.6(2)(k) and 2.06.8(3)(c)). The Yampa River valley meets the requirements to be classified ae an AVF. Land use along the Yampa river consists primarily of irrigated hayland and pastureland. Cropland is both irrigated and subirrigated. The potential for the Yampa river AVF to be impacted is negligible. Generally, the Yampa River AVF receives very little of its water supply ( surface and ground water ) from the proposed mine area. The majority of the flow in the river and subsequent recharge to the alluvial aquifer comes from the headwater portions of the drainage. The applicant states that the contribution of surface water from the Trapper mine is insignificant and is estimated at .07cfs/mil. Furthermore, the ground water contribution to the base flow of the Yampa River is undetectable. This is substantiated by seepage, runoff, and potentiometric studies (see appendix H of the permit application) which show that; 1) The Yampa River loses surface water flow to the alluvial aquifer as it flows past the mine area, and 2) the Yampa River alluvial aquifer is hydraulically isolated from the bedrock aquifers of the Williams Fork Formation. In addition, all disturbance related to the mine is located at least one mile from the southern boundary of the Yampa River AvF. Based on the information presented by the applicant, the Division concludes that the proposed mining operation will not impact the Yampa River AVF. v The potential for impact due to mining to the Williams Fork AVF is also negligible. The Williams Fork River is located south of the proposed mining area. Disturbed areas draining to the Williams Fork River are located in Elk, Ute, and Deer drainages, all of which are extremely small (less than 30 acres each). Surface discharge from the associated sediment ponds in each of these drainages is limited to spring snowmelt almost exclusively. Due to the downstream configuration of the geologic strata, complete infiltration of all pond discharge will most likely occur prior to reaching the Williams Fork River. Ground water flows away from the Williams Fork River and ground water in the vicinity of the mine is not hydraulically connected to the Williams Fork River. Therefore, the Division concludes that the Williams Fork AVF will not be impacted by / mining. 13. The Division hereby approves the post-mining land use of the operation. It was determined that rangeland and ~=ropland meets the requirements of Rule 4.16 for the permit area. (2.07.6(2)(1)). la. Specific approvals have been granted or are proposed. These approvals are addressed in the following section, Section B. (2.07.6 (2)(m)). 15. The Division finds that the activities proposed by the applicant would not affect the continued existence of endangered or threatened species or result in the destruction or adverse modification of their critical habitats. Bald eagles are a winter resident of the mine area and nesting Bald eagles have been documented in recent years at the Craig Municipal golf course (approximately 4 miles north). Threatened species of fish exist in the Yampa River downstream of the proposed mining operation. No impact to either of these species has been observed from past mining activities at the Trapper Mine and none ie projected. (2 .07.6(2)(n)). Page 15