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1 <br />' be replaced with unlined ponds which are or will be hydraulically connected to the alluvium and <br />' stream. Other portions of the alluvium will be replaced with lined storage reservoirs, N•hich will be <br />removed from hydraulic connection to the stream. Other portions of the alluvium will be removed <br />and reclaimed at lower elevations than the current ground and stream surface elevation. Low <br />permeability barriers will be installed at the boundaries of these areas to inhibit the flow of alluvial <br />' ground water into these areas. As a result of these mining and reclamation activities, the alluvial <br />ground water system will be affected in and near the mined areas, both during and after mining. <br />' 1.3 Purpose and Scope of Study <br />1 <br />Changes to the ground water system brought about by mining and reclamation at the Lyons - Rockin' <br />' V/P Pit may result in the following impacts to the hydrologic system: <br />' Possible changes to ground water levels in local wells, and corresponding changes <br />in the production capacity of the wells. <br />' Impacts to the alluvial aquifer -stream system relationship which may affect the <br />timing of flows in the St. Vrain River stream system due to changes ;n the storage <br />' function historically performed by the alluvium. <br />• Depletions to the St. Vrain River stream system due to the mining operational water <br />' losses and evaporation from unlined pits which expose alluvial grou~td water. <br />1 The purpose of this report is to evaluate the first two potential impacts listed above: (1) changes to <br />' local ground water levels and possible impacts to neighboring wells; and (2) impacts to the alluvial <br />aquifer -stream system relationship brought about by the elimination of aquifer storal;e, Depletions <br />to the St. Vrain River stream system are required to be offset under Colorado law by a plan for <br />augmentation or substitute water supply plan. Such a plan will be presented separately and is not <br />' the subject of this report. <br />1 <br />' -3- <br />' 1 /t i../up~Hni~dni .I.r.ru~misc. Air. <br />