Laserfiche WebLink
<br /> <br /> <br /> 64 C1981-041 RN7 findings <br /> <br />Alluvial Valley Floor – Findings (Facilities Area) <br /> <br />Those portions of the permit area within Sections 26, 27, 28, 33 and 34 are exempt <br />from the requirements that prevent an operation from interrupting, discontinuing, or <br />precluding farming, and from affecting the quantity and quality of water supplying <br />the alluvial valley floor (4.24.3(4)). <br /> <br />However, this area is not exempt from the requirements for restoring the essential <br />hydrologic functions of the alluvial valley floor, which will be discussed below, in <br />Item 3. <br />All of the non-exempt alluvial valley floor is located outside the permit area within <br />Section 26 and 27. <br /> <br />1. No portion of the non-exempt alluvial valley floor is presently disturbed by the <br />mining operation. A small portion of this area is indicated as being historically <br />flood irrigated on Exhibit 33. There are no plans to disturb any additional land on <br />the alluvial valley floor. Therefore, the proposed coal mining operation will not <br />interrupt, discontinue, or preclude farming on the alluvial valley floor (4.24.3(1)). <br /> <br />2. As previously discussed, a portion of the non-exempt alluvial valley floor was <br />historically flood irrigated. In addition, a portion is subirrigated. The remaining <br />area is potentially flood irrigable. Surface waters which could be and were used <br />to irrigate the non-exempted alluvial valley floor would be diverted from the <br />Highline Canal. Water in the Highline Canal is diverted from the Colorado River <br />approximately one mile upstream of the disturbance. The Highline Canal will not <br />be affected by subsidence or by mine discharges. Therefore, the quantity and <br />quality of surface water which supplies the AVF would not be affected by the <br />proposed operations (4.24.3(3)). <br /> <br />Discharge from the Roadside and Cameo Mines will have a minor salt loading <br />effect on the Colorado River. The effect on the water quality from this discharge <br />will be to increase the specific conductance and total dissolved solids about 0.2 <br />percent. This, in turn, would have a minor effect on the water which supplies the <br />subirrigated portion of the AVF, since recharge water from the adjacent Colorado <br />River is the source of alluvial groundwater which subirrigates the AVF. <br /> <br />During mining, the sediment control system will temporarily reduce surface flows <br />and will remove sediment loads. Sediment ponds will not remove dissolved <br />solids. Thus, the mine operation will increase salt loads. Reduction in flow will <br />only occur during significant precipitation events and possibly during spring <br />snowmelt. During these events, flows will be reduced for only a period of 24 <br />hours. Even then, the amount of water stored in the sediment ponds is minor <br />compared to the average flow of the Colorado River (3549 cfs). <br /> <br />All effects from the mining operation will be short-termed. With reclamation and