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MMRR quarry DMG Adequacy Review Response <br />3/15/2005 <br />Page 4 <br />median diameter of approximately six inches, less than 10% passing the <br />#200 sieve and placed approximately three feet deep. <br />c) Calculation of the PMP is not warranted for this situation. The top of the <br />waste rock pile is designed such that any storm runoff overtopping the <br />diversion ditch will flow around the waste rock pile, and not pond on the <br />pile. The waste rock pile contours shown on Exhibit F, Reclamation Base <br />Map, illustrate how water will run off the Waste Rock Pile. <br />Construction, Draina¢e and Erosion Control Sequence <br />Following the excavation of roads and working azeas, construction will occur in a "top-down" <br />sequence using ripping and drilling and blasting where necessary. Topsoil will be salvaged for <br />later use in re-vegetation if feasible, however in this steep terrain with significant rock exposures, <br />the thickness and availability of topsoil is quite litnited. <br />Runoff from undisturbed land will be diverted around construction areas wherever feasible. <br />Runoff from areas under construction or mining areas will be directed to sediment ponds. <br />Diversion ditches to be removed and reclaimed following mining will be sized to convey the <br />runoff resulting from a 10-year 24 hour precipitation event. Diversion ditches that will remain as <br />permanent structures following the completion of mining will be sized to convey the rnoff <br />resulting from a 100-year storm event. Sediment ponds will be constructed to contain the volume <br />of runoff resulting from a 10-year 24 hour precipitation event. The spillways for temporar}' <br />ponds will be sized to pass flows from the 10-yeaz 24 hour precipitation event and spillways for <br />permanent ponds the 100-year 24 hour event. <br />The following list shows the constmction sequence for the mining operations, and ivhetheror not <br />the facility is planned to be temporary or permanent. Some facilities may be constructed <br />concurrently. <br />Staeina Area and Access Road lEahibit C-2A) <br />I. Staging azea adjacent to SH 119 -Permanent <br />The fast element to be constrcted will be the staging azea adjacent to SH 119 (Exhibit <br />C-2A). Temporary wnstretion erosion control measures; consisting of sediment control - <br />Best Management Practices including silt fences, straw bales diversion ditches and <br />sediment ponds will be utilized. The 50 foot wide staging azea adjacent to the CDOT <br />R/W will be used for unloading equipment, loading trucks and excavation of a sediment <br />pond. <br />2. Access Road/Staging Area Sediment Pond -Permanent <br />The sediment pond will capture disturbed area runoff from the Access Road and Staging <br />Area. Mast precipitation falling on the benched slopes will retained in the soil and <br />vegetation on the flat benches, and not appear as runoff. <br />3. Undisturbed azea flowing to the Access Road <br />Runoff from this area will be allowed to flow onto the benches to provide water for the <br />vegetation <br />4. Access Road -Permanent <br />