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(Version 2) may not be necessary. Please review the drainage control plans for <br />the South Taylor Pit, including the East Taylor Fill area, to determine <br />whether the Section 16 Taylor Ditch (Version 2) is necessary. Based on the <br />conclusions of this review, please revise Map 12, Map 33A, Map41 and Map <br />41A as necessary. <br />d. With the proposed change to the post-mining topography, Colowyo is proposing <br />to dramatically alter the final cut of the Section 16 Pit. In the approved post- <br />mining topography Colowyo has a permanent ditch, the East Taylor Ditch, <br />running down the middle of the final cut of the Section 16 Pit, which ultimately <br />reports to the East Taylor Pond. In the proposed post-mining topography <br />Colowyo has eliminated this ditch and has returned the final cut of the Section 16 <br />Pit to more of a peak/ridge, like it was prior to mining. While the Division <br />generally likes this approach, there are several issues that need to be addressed. <br />First, based on the proposed post-mining topography, Colowyo will be <br />eliminating a large portion of the East Taylor Ditch. The final cut of the Section <br />16 Pit will be filled to approximately station 95+00 of the East Taylor Ditch. This <br />will eliminate the entire upper portion of the East Taylor Ditch (form <br />approximately station 95+00 to approximately station 150+00). Colowyyo still <br />shows this ditch in its entirety on Map 12, Map 33A and Map 41. Second, with <br />the complete filling of the final cut of the Section 16 Pit proposed in Technical <br />Revision 81, Colowyo has not addressed how the runoff from this area will be <br />handled. The elimination of the upper 5,500 feet of the East Taylor Ditch leaves a <br />large area of reclamation that will have no hydrologic control. This could lead to <br />massive sheet flow and erosion. Third, it appears as though the size of the East <br />Taylor Watershed will be decreased in the Section 16 Pit area and the size of the <br />Streeter Watershed, the Section 16 watershed and possibly the Prospect watershed <br />will be increased. <br />i. Please change the design of the East Taylor Ditch to reflect the <br />proposed changes to the post-mining topography. Please change the <br />design on Map 33A and please provide new SEDCAD modeling for <br />the redesigned ditch. Please include the new location of the East <br />Taylor Ditch on Maps 12,41 and 41A. <br />ii. Please review the proposed changes to the area of the final cut of the <br />Section 16 Pit and determine how Colowyo will control the runoff <br />from this area. Please include ditch locations and SEDCAD modeling <br />for these ditches as necessary. <br />iii. Please update the watershed boundaries for the East Taylor, Streeter, <br />Section 16 and Prospect watershed boundaries as necessary. If, based <br />on these changes, any of the watershed boundaries have changed due <br />to the changes in the proposed post-mining topography, Colowyo will <br />(including but not limited to providing new SEDCAD modeling for <br />the affected ponds to ensure they can handle the additional runoff). <br />e. Map 41 A does not have the northing and easting grid or datum values like the <br />other maps do. Please add the northing and easting grid and datum values to <br />Map 41A.