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Pond 008 was constructed in an area which contained three small stock ponds on the Burbridge <br />property. The landowner has provided a letter stating that he would like Pond 008 to remain to <br />replace the three ponds which existed in the pre -mining condition. This letter is provided in <br />Attachment 2.05.4(2)(c)-4 at the end of this section. Compliance with Rule 4.05.9(13)(a) through <br />(f) for pond retention after reclamation is enclosed in Attachment 2.05.3(3)-19. <br />Postmining Roads <br />All of the original roads that cross the New Horizon Mine have been restored to original <br />conditions and Montrose County standards. Per the request of Benson and Kirkwood, the portion <br />of the BB Detour Road on their respective properties will be left in place to provide access to the <br />CCC ditch headgate. A letter approving this retention can be found in Attachment 2.05.3(3)-17. <br />Postmining Drainage Channels <br />All major drainages that are to be disturbed by mining activities will be reclaimed to <br />approximate the pre -mining configuration and to blend with the undisturbed drainage above and <br />below the area to be reclaimed. Two pre -mining channels are encountered and restored. These <br />are called the Krill Channel, on the easternmost portion of the mined area, and the San Miguel <br />Channel, which drains into the reclaimed area of Pond 007. Both of these channels are shown on <br />Map 2.05.3(3)-1 Surface Hydrology. The post -mining drainage channels will be designed, <br />constructed, and maintained to the following specifications: <br />1. Gentle, sloping banks which shall be stabilized by vegetation; <br />2. Prevent additional contributions of suspended solids to streamflow and to runoff outside <br />the permit area; <br />3. Blend with the undisturbed drainage above and below the area to be reclaimed; <br />4. Safely pass the runoff from a 10 -year, 24-hour precipitation event. <br />The reclaimed drainages are designed to safely pass the 10 -year, 24-hour precipitation event and <br />to be stable. The peak flow was determined using the SEDCAD computer program. A listing of <br />the input parameters for obtaining the peak flows for the reclaimed drainage channels are shown <br />in the appropriate channel attachment. The peak flow determination assumed the total watershed <br />of the reclaimed channel and was determined at the downstream end of the channel. Most of the <br />reclaimed channel will not have to handle that large a peak flow rate. This was done to ensure <br />that the drainage channel capacity will be adequate and yet conservatively designed. <br />A limiting permissible velocity of 5.0 feet per second was used to ensure the postmining <br />drainage channels would be non -erodible and stable. The permissible velocity was obtained, <br />Table 3.4, from "Red Book" by Barfield et al., 1981 for a grass mixture vegetated channel. The <br />Page 2.05.4(2)(c)-6 July 2018 (TR -84) <br />