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little protection offered to the degasification pad. The Division suggests that a second <br />typical deeasification well pad be submitted for review that accounts for shallow <br />hills lopes. Please include in the submittal a justification of maximum hillslopes for the <br />design and a diagram. A small area exemption must be provided for these typical pad <br />designs in compliance with Rule 4.05.2(3). <br />Oxbow Response: The most recent Typical GVB design was prepared for TR -67 in 2010. <br />Typical designs are intended to represent the features that are commonly found on a GVB site, <br />but not representative of any specific site. We have modified the attached drawing to remove the <br />reference to the little used clean water diversion, added reference to the SAE status and added <br />additional clarification language. <br />7. Drawing 2.05 -M4 (3/4) shows that Ditch D -6 flows on the west side of the Elk Creek Fan <br />to Ditch D -2 and ultimately to Elk Creek. Ditch D -6 also passes by the rock dust bins <br />which have a considerable amount of dust on the ground surrounding the bins. Due to <br />the proximity of the rock dust bins to Ditch D -6, the ditch has been diverted away from <br />Ditch D -2 to Ditch D -5 which drains to sediment Pond D. While the Division supports <br />this change it is unclear if Pond D has the capacity to support the extra runoff. Please <br />submit revised maps and data showing that Pond D has the capacity to treat the additional <br />runoff of Ditch D -6 in accordance with Rule 4.05.6. <br />Oxbow response: Please find attached SEDCAD Runs for the 10 yr -24hr event and the 25 yr -24 <br />hr event routed to as-built for Pond D. We added the small Ditch 6 watershed (10.5 ac) to the <br />SEDCAD runs. As we suspected it had little impact on Pond D. The pond still does not discharge <br />through the emergency during the 10 yr, the discharge still has a peak settable concentration less <br />than .5 ml /l, and we still maintain over a foot of freeboard during the 25 yr storm event. <br />Attached is a revised drawing 2.05 -M4, Sheet 3 of 4 showing the current configuration of the <br />ditches. <br />Please contact me at 970 - 929 -5806 if you any questions or comments regarding this permit <br />renewal application material. <br />Sincerely, <br />J amk,es A. Kiger <br />Environmental Manager <br />Attachments <br />Xe: Michael Ludlow, (OMLLC) <br />Delta County <br />Gunnison County <br />USFS, PRD <br />BLM, UFO <br />Paonia Library <br />Files <br />• Page 5 <br />