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2011-06-02_APPLICATION CORRESPONDENCE - C2010089 (19)
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2011-06-02_APPLICATION CORRESPONDENCE - C2010089 (19)
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Last modified
8/24/2016 4:34:06 PM
Creation date
9/8/2011 1:00:33 PM
Metadata
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Template:
DRMS Permit Index
Permit No
C2010089
IBM Index Class Name
Application Correspondence
Doc Date
6/2/2011
Doc Name
BBA Water Consultant Report
Section_Exhibit Name
Section 2.05.6(3) Appendix 2.05.6(3)-1a
Email Name
MLT
Media Type
D
Archive
No
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• <br />• <br />• <br />Murari P. Shrestha, P.E. <br />August 25, 2010 <br />Page 6 <br />resulting in more water in the stream system during the irrigation season. <br />To determine the timing of the interception of the return flows and pumping of naturally <br />occurring ground and surface water pumped from the pit, we relied on the aquifer <br />characteristics determined for the coal and overburden materials presented above and the <br />IDS AWAS software. The points of depletion for the dewatering of the mine areas were <br />determined from structural geologic mapping of the top of the coal seam provided by <br />Western Fuels and USGS topographic mapping. The points of depletion for the New <br />Horizon North, New Horizon and Cyprus Block mine locations were determined to be a <br />tributary of Coal Canyon, Tuttle Draw and Calamity Draw, respectively, as presented on <br />Figure 2. Centroids were determined for each mine area and the distances from the points <br />of depletion to the centroids were measured using GIS methods. Dewatering pumping <br />records provided by Western Fuels for the existing New Horizon mine indicate that the <br />average dewatering pumping amount is approximately 57 acre -feet per month at the <br />existing New Horizon Mine. <br />In order to determine the worst case impact to the stream system resulting from the <br />dewatering operations, we completed a lagging analysis based on the direct lagging of the <br />average monthly dewatering pumping. This scenario is the worst case scenario, in that it <br />assumes that pumping from the pit is a complete depletion to the stream system and not <br />the interception of a return flow. The results of this lagging analysis for the New Horizon <br />North, Cyprus Block and New Horizon mine locations are presented in the attached Table <br />Nos. 6.A through 8.A and in the attached Figure Nos. 6.A through 8.A. The month of <br />peak pumping occurs in the month of September, and the month of peak lagged depletion <br />occurs in the month of October. Lagging factors for the dewatering from the three mine <br />areas are also presented in Tables 3.B, 4.B and 8.B and shown in Figures 6.B through <br />8.B. In general, the dewatering operation results in more water delivered to the stream <br />system than would otherwise occur in June through November. A lagged depletion to the <br />stream system occurs in the months of December through May. Because most water <br />rights divert in the irrigation season, and particularly need water in the late irrigation <br />season, the dewatering operation benefits irrigation water rights. We understand from Mr. <br />Wayne Schieldt, that although a depletion occurs outside of the irrigation season, there <br />are no water rights on these drainages that are impacted by the lagged depletion outside <br />of the irrigation season. <br />Location of Dewatering Pumping Impacts with Respect to Mining Operations <br />At the location of the mine areas, return flows and naturally occurring ground and surface <br />water discharge occur to various tributaries of the San Miguel River, including Coal <br />Canyon, the Second Park Lateral, Tuttle Draw, Calamity Draw and other small <br />tributaries. The location and amount of pre- mining return flows and naturally occurring <br />discharge occurring in these drainages is controlled by the irrigation in the drainages, the <br />surface topography in the drainages and to a lesser extent the geology within these <br />drainages. It appears from discussions with Western Fuels, available information on the <br />local geology and our field investigations, that ground water return flows flow primarily <br />within the unconsolidated near - surface materials (alluvium, colluvium and terrace <br />deposits, and weathered bedrock) which are present on top of the less permeable bedrock <br />material. Mining operations have potential to alter the flow paths of some of this ground <br />www.bbawater.com <br />Bishop - Brogden Associates, Inc. <br />
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