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C -1981 -008 TR -60 <br />PAR No. 2 <br />10- Nov -2011 <br />Page 3 of 4 <br />b) Page 2.05.3(3) -7, second paragraph — please replace this paragraph with the following <br />sentence: "Updates and modifications to the mine pit dewatering plan are described in Section <br />2.05.3(3), subsection 6." Item resolved. <br />c) On page 2.05.3(3) -12, the first sentence should read, "...WFC will use Ponds 008 through <br />015 ", rather than 014. Item resolved. <br />d) In the table on page 2.05.3(3) -12, please revise to show that Pond 007 is shown on Maps <br />2.05.3(3) -2 -1 and -2 -2, and that Pond 008 is shown on Maps 2.05.3(3) -4 -1 and -4 -2; Item <br />resolved. <br />e) In the last paragraph on page 2.05.3(3)12, the second sentence should read, "Pond 011 and <br />Pond 013 will have.. Item resolved <br />f) Page 2.05.3(3) -14, fifth paragraph — please replace the last two sentences with the following: <br />"Mine pit dewatering was transferred from Pond 011 to Pond 013 in June 2011. These changes <br />are reflected in the amended NPDES permit. The cover letter submitted with the response <br />indicates that anew page 2.05 3(3) -14 was attached However, it appears that page -13 was <br />attached instead Please provide a revised page 2.05.3(3) -14. <br />g) On page 2.05.3(3) -19, last paragraph, please add that Pond 012 was excavated in Spring 2005, <br />and revise the third sentence to state that Ponds 011 and 013 were constructed in late 2008. <br />Please add that Pond 014 was constructed in Spring 2004, and reclaimed in Fall 2009. Item <br />resolved, and the Division appreciates your correction that ponds 011 and 013 were <br />constructed in late 2007, not 2008. <br />4. Attachment 2.05.3(3) -1 Collection Ditches and Culverts <br />a) The As -Built Drainage Area for Ditch C27, which flows to Pond 015, is given as 6.163 acres, <br />which is less than half the 12.6 acres used in the design. Please provide an explanation of the <br />reduction in area. Explanation provided, response accepted. <br />b) The runoff curve number, CN, for Ditch C27 has been reduced from 79 to 76. Please provide a <br />rationale for the curve number selected, including the assumed Hydrologic Soil Group and any <br />other factors considered. Explanation provided; response accepted <br />c) For Ditch C27 channel design, the as -built Bed Slope is given as 2.04 %, while the Design <br />slope was given as 6.50 %. During an earlier field inspection of the site, prior to construction, <br />Ross Gubka indicated that the ditch gradient would be approximately 0.5 %. Please verify that <br />the value used is consistent with the ditch as constructed. Explanation provided; response <br />accepted.. <br />d) The Channel Lining is now described as "Sandy loam noncolloidal ". During a site inspection, <br />the channel was observed to be lined with materials of varying characteristics, including <br />fractured rock. Please verify that accurate materials and values have been considered and <br />selected for incorporation into the analysis. Explanation provided, response accepted. <br />e) For Ditch D 1 W, which diverts "clean" water from the as- yet- unmined western area of the <br />permit, the Drainage area has been reduced — from 12.6050 acres to 6.7800 acres. The text <br />explains that this is due to the contributions of several different sub - watersheds. (No response <br />is needed.) Explanation provided; response accepted. <br />5. Attachment 2.05.3(3) -18 - NPDES Permit <br />