2014-07-03_PERMIT FILE - C1981020A

Home Browse Search

I~ 2.3 MINING HYDROLOGY The objective of these studies is to provide an evaluation of the surface water runoff from the mine area and potential for ground water impact to serve as a basis for final design and operation. 2.3.1 Surface Water Hydrolooic Controls Surface runoff areas have been subdivided into disturbed and undisturbed L~ areas, see Figure 2.3-a. Runoff from disturbed areas will be routed into or through appropriate sedimentation controls that will insure compliance with all applicable effluent limitations when discharged into the ephemeral drainage of Munger Creek or into East Salt Creek. Runoff from the undisturbed areas will be diverted around the disturbances and routed to a natural channel. (The design of waste rock disposal area sedimentation pond is addressed in Section 2.2.5). The project area was divided into eight watersheds which are shown on Figure 2.3-4. The individual watershed areas range in size from 18 acres to 4,800 acres. Hydrologic parameters of each are given in Table 4.5-11. Rainfall values fora 10 year 24 hour precipitation event and runoff rates were established according to Technical Manual No. 1, a Manual for Estimating Flood Characteristics of Colorado. Then Munger Canyon site is not located near a gauged stream of reference in the manual; therefore, regression equations were derived from the manual. Eight drainage areas shown in Figure 2.3-4 with potential effect on disturbed areas associated with the Munger Canyon project, received the most attention and were evaluated as to degree of impact. The size of the culvert needed to pass flow under the roads, around the mine bench and around the waste rock disposal area were based on calculations made on these drainage areas, see Section 4.5.3.3.2. The overall hydrologic regime of Munger Canyon is addressed in Section 4.5. Permit Renewal z-za 09/03