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<br />Division of Minerals and Geology <br />Iuly 30, 2004 <br />Page Two <br />~~~ <br />li1lDUSYRIES <br />however groundwater measurements show that groundwater levels at the monitoring well in the <br />northwest corner of the property (MW-4), upgradient of the slurry wall, have been within two- <br />feet of the natural ground surface during three consecutive weekly measuring events, thus <br />triggering the commitment to install the drain in accordance with permit conditions. Enclosed for <br />your reference are the groundwater measurement data for all monitoring wells updated through <br />July. Also enclosed is a drawing showing the location of the monitoring wells. <br />AI has not been directly contacted by any neighbors regazding problems associated with the <br />recent high groundwater levels, however Kate Pickford from the Division advised on Wednesday, <br />July 28, that she had been contacted by neighbor Duane Viney, who resides west of the Stegner <br />mine. In order to alleviate high groundwater problems that he is experiencing, AI representatives <br />are attempting to contact Mr. Viney today to discuss temporary mitigation measures until the <br />drain is approved. Upon the Division's approval ofthis technical revision request, as well as <br />review and approval by the Larimer County Engineer's Office, AI will proceed with installation <br />of the drain. <br />2. Reconfiguration of land and pond features. The configuration of land and pond features, as <br />shown on the enclosed revised reclamation plan, have changed slightly from that which appears <br />on drawings cun•ently on file with the permit for the Stegner operation. Originally, an earth <br />embankment constructed from overburden and topsoil was proposed to create two separate ponds <br />on the site. The property owners now desire to expand the fill area at the east end of the property <br />along Taft Hill Road, backfilling the mined area to approximately the original grade, thus <br />eliminating the need for the earth embankment and creating only one pond. As mining of this site <br />has generated more unusable material than originally anticipated, this technical revision does not <br />propose to import any off-site material for reclamation. Final contours of the backfilled land <br />mass as delineated on the enclosed drawing may vary slightly dependent upon actual overburden <br />and topsoil material available on site but will generally be reclaimed to original grade or slightly <br />above. <br />A shallow Swale will be constructed along the southern corridor of the property to provide a <br />surface drainage channel to the southeast comer of the property. The water level of the pond will <br />be controlled at an elevation of 5037 by anerosion-resistant spillway, constructed at the historic <br />elevation of the property at the southeastern point of the pond to the constructed Swale. <br />Additionally, a drainage pipeline will be constructed to passively drain approximately nine feet of <br />water from the lined pond in the winter months. The spillway and Swale system is designed to <br />safely divert excess precipitation and prevent over-filling the reservoir with approved irrigation <br />ditch water. Off-site surface water is diverted around the northern property boundary, outside of <br />the permit area, by the borrow ditch on the south side of County Road 54G, which will be <br />enhanced in the future with a drainage easement the land owner has dedicated to Larimer County. <br />Grading, topsoiling and revegetation as proposed in the current reclamation plan are generally not <br />affected by this revision. As stated in the June 24, 1999 response to the Division's initial technical <br />adequacy review dated April 30, 1999, the post-mining land use under this permit is described as a <br />