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Current mining taking place under the approved Plan of Operations with associated <br /> impacts,will continue, irrespective of the proposed modification approval. <br /> Protective/Mitigation Measures: None <br /> Finding on the Public Land Health Standard for Upland Soils: <br /> A site specific evaluation of the area has not been conducted; however the nature of the <br /> Proposed Action would essentially make the soils not meet standards during operations. Upon <br /> successful reclamation, soils would be anticipated to meet standards. <br /> 3.2.4 WATER SURFACE AND GROUNDWATER,FLOODPLAINSI (includes a finding <br /> on standard 5) <br /> Affected Environment: <br /> The Proposed Action takes place on a bench directly adjacent to the Arkansas River. The <br /> lower toe of the project area is likely near the flood stage level of the river; however, floodplain <br /> mapping of the site is at a course scale and the exact flood level is difficult to determine. It is <br /> possible that the 100 year flood level is within the proposed area; however, due to the <br /> topography of the site it doesn't exhibit floodplain characteristics. Historic and present mining <br /> has cast material down on a frequently inundated lower bench and high flow has transported <br /> material from the site. <br /> Water quality in the Arkansas River at this location is good and is not identified as being <br /> impaired by the State of Colorado. Historically, the water quality in the river has been heavily <br /> impacted by heavy metals due to historic mining in the headwaters areas,mainly around <br /> Leadville. Over the last 30 years tremendous improvements have been made to improve the <br /> water quality throughout the watershed. Groundwater with the proposal is associated with the <br /> alluvial aquifer along the river. At this site, this aquifer is very narrow and is very closely <br /> hydrologically connected to the river. Essentially,near groundwater and surface water are <br /> I identical in this location. <br /> Environmental Effects <br /> Proposed Action <br /> Direct and Indirect Impacts: Water usage and impacts from the proposal would be two <br /> fold. First, the proposal would pump water out of the Arkansas River using a pump that would <br /> be capable of using approximately 150 gallons per minute. The water would then flow through a <br /> sluice draining into a settling basin before reentering the river. The material being worked is <br /> alluvial in nature and not expected to introduce any new or elevated levels of constituents into <br /> the river. The settling pond would keep most sediment from entering the river. The second <br /> impact would be the physical disturbance of the site. The removal of vegetation and soil <br /> disturbance leads to increased runoff and sediment transport. If the site is not reclaimed <br /> properly,this impact could persist for a long period of time. This is mainly a concern during <br /> high intensity rain events as runoff could transport sediment into the river,however any <br /> precipitation could transport sediments into the river. The implementation of proper stormwater <br /> controls, interim reclamation and final reclamation are essential to mitigating this impact. <br /> Overall, with mitigation, the Proposed Action would have little impact on water quality <br /> in either the short term or long term. In addition, this operation modification may require further <br />