2018-05-30_PERMIT FILE - M2018028

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larger material. This could leave voids and a different density of material under the topsoil resulting in changed water holding capacity and root growth medium. Overall,the Proposed Action would impact up to 0.6 acres of soils until reclamation is considered complete. In the long term, after reclamation is considered complete,the soils would be essentially similar to their current condition. b. Protective/Mitigation Measures: i. Performance expectations for the established vegetation will be based on an optimum ground cover of 40%for the native seed mixture suggested in section 3.3.3 Vegetation(not including annuals),understanding that this is an ideal situation given that current vegetation conditions are not meeting these specifications. In addition, successful reclamation will include stable soil conditions at natural background erosional rates. ii. On any slopes that are greater than 3:1, excelsior matting is suggested to be installed following the manufacturer's installation instructions to reduce erosion rates on disturbed soils. iii. In order to maintain as much topsoil as possible and in addition to the upgradient Stormwater controls to be installed as described in the Plan of Operations modification,it is suggested that downhill portions of the soil stockpiles have controls installed also, such as straw wattles or silt fencing to prevent soil from leaving the disturbed area. 3. Water(Surface and Groundwater,Floodplains) a. Impacts: Water usage and impacts from the proposal would be two fold. First, the proposal would pump water out of the Arkansas River using a pump that would be capable of using approximately 150 gallons per minute. The water would then flow through a sluice draining into a settling basin before reentering the river. The material being worked is alluvial in nature and not expected to introduce any new or elevated levels of constituents into the river.The settling pond would keep most sediment from entering the river. The second impact would be the physical disturbance of the site. The removal of vegetation and soil disturbance leads to increased runoff and sediment transport. If the site is not reclaimed properly,this impact could persist for a long period of time. This is mainly a concern during high intensity rain events as runoff could transport sediment into the river,however any precipitation could transport sediments into the river. The implementation of proper stormwater controls,interim reclamation and final reclamation are essential to mitigating this impact. Overall,with mitigation,the Proposed Action would have little impact on water quality in either the short term or long term. In addition,this operation modification may require further permitting from the State of Colorado under the Clean Water Act in the form of a 401 certification,NPDES,or other permit. The operator is required to obtain any other permits necessary before beginning work. These permits would further ensure water quality is protected. b. Protective/Mitigation Measures: i. The site must be maintained in such a way that soil stays within the work area and does not leave the perimeter of the disturbance or enter the river.