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LRE <br />Landscape, Resource, Ecosystern Planning, Inc, <br />P.O. Box 5, Allenspark, CO 80510 mfiggs@indra.com <br />Phone 970-577-0200 Fax 70,-577-9922 :Mobile 303-579-5821 <br />September 2, 2008 <br />Monica Sowders, Environmental Manager <br />Cemex, Lyons Plant <br />5124 Ute Highway Box 529 <br />Lyons, CO 80540 <br />Re: Update to Wildlife Resources Assessment, Cemex C-Pit and CKD Disposal Site, <br />Boulder County, Colorado <br />Dear Monica: <br />Enclosed is a letter update to the above referenced report, issued in September 2004. <br />This report described the wildlife habitat types and potential wildlife species present at <br />the Cemex C-Pit site, identified federal and state wildlife species of concern in the habitat <br />types present, and discussed potential impacts to wildlife from the presence of <br />approximately 100 acre feet of water in C-Pit. Wildlife mitigation options were also <br />discussed. <br />Introduction <br />When cement kiln dust (CKD) disposal began in C-Pit in the mid 1990's there was a <br />small amount of water in the bottom of the pit, generally well under one acre foot. By the <br />time of the Wildlife Resources Assessment in 2004 additional water had accumulated in <br />the bottom of the pit, and water volume has expanded up to approximately 100 acre feet, <br />with several acres of surface water (Figure 1). This water was in contact with the <br />disposed CKD, and resulted in the water in the bottom of the pit having a pH of <br />approximately 12. Water at this pH level was potentially hazardous to any wildlife that <br />came into contact with this water. <br />Wildlife Resources Assessment <br />In the Wildlife Resources Assessment conducted 2004 I determined that the probability <br />of adverse impacts to wildlife from this water in C-Pit was low to very low. At the time <br />of the report wildlife had not been observed in the bottom of the pit, and the only known <br />wildlife near the pit were rock doves. However, given that contact with the water was <br />potentially hazardous or life threatening, mitigation measures were recommended. It was <br />further recommended that mitigation focus on a permanent, long term solution, <br />particularly with respect to reduction of ground water infiltration, rather than short term <br />measures that did not address the underlying problem of water infiltration into the pit. <br />Subsequent Actions by Cemex <br />Since the time of the Wildlife Resources Assessment in 2004 Cemex has taken the <br />following actions to address a long term solution, as recommended in the report: <br />1. The Swede Ditch, immediately to the west of C-Pit, has been relined in order to <br />prevent leakage into the pit.