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0 <br />Mr. Robert Zuber <br />April 23, 2014 <br />Page 2 <br />Response: Map 2.05.3(3) -21 has been revised with a new Detail A that has smaller rock next to the <br />pipe. HDPE pipe similar to the DR 9 (200 psi) shown on the attached specification sheet will be utilized for <br />the trench drain installation. This specification sheet has been provided for information purposes only, and is <br />not intended to be part of the permit application package. The specification of pipe was selected based on <br />operator experience in pipe installation, and the need for the pipe to withstand the load of rock, backfill, and <br />heavy equipment employed during reclamation operations. <br />The pipe selected will have a wall thickness just over two inches and is rated to loads up to 200 psi. The <br />static load at which the pipe is buried at its deepest is estimated to be 15 psi (20 feet of backfill at a density of <br />90 pef plus 3 feet of rock at density of 125 pef). The dynamic load of equipment can be assumed to be <br />similar: 15 -20 psi (ex: a CAT D9 dozer produces roughly 16 psi of pressure at ground contact). This gives a <br />total peak load of 35 psi, well below the 200 psi rating of the selected HDPE pipe. <br />Additionally, the size and layering of rock to be placed on Segments A and B has been reduced (see revised <br />Detail A on Map 2.05.3(3) -21). <br />DRMS Item 6. Afore detail is needed regarding the pipe connection at the lower ends of Segments A and B. <br />Will a "T" connection he used? Neither the text nor Detail C on Map 2.05.3(3) -21 provides this information. <br />Also, in Detail C why are there two colors of rock that appear to be the same size? Please elaborate on this <br />nexus. <br />a. The response addresses the cot fitsing term "rock draw. " but there uppears to be another <br />problem with the text box on Map 2.05.3(3) -21. The tart indicates that the spring water <br />flo- s fron the nexus into u perforated pipe, but the pipe below the nexus is solid rather than <br />perforated per other in fornnation in the submittal. <br />Response: The text block has been revised to remove the perforated pipe reference. <br />DRMS Item 7. Ott Xfop 2.05.3(3) -21 a text bow pointirng to the nexus of segments states that "Rock drenr <br />drains into perforated pipe. " Is this incorrect? <br />Response: RESOLVED <br />DRMS Item 8. Ott Map 2.05.3(3) -21, Segments A and B tire shown approximately 15 feet from the <br />highwull. However, Detail A indicates that these features are located much closer. Please explain this <br />discrepancy. <br />Response: RESOLVED <br />DRMS Item 9. The spoil spring is not shown on A-lup 2.05.3(3) -21, although the proposecl text indicates that <br />this location is shown on the map. <br />Response: RESOLVED <br />DRMS Item 10. In the approved PAP, the surface water lrvdrologv map showing post mine drainage areas <br />(Map 2.05.3(3) -1 -2) indicates that the area that reports to Pond 013 is 82.9 acres. However, in the SEDCAD <br />AN EQUAL OPPORTUNITY I AFFIRMATIVE ACTION EMPLOYER <br />