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• 007 WEST DITCH <br />The topography of the land at New Horizon Mine slopes gently to the southwest at approximately <br />3%. To provide vehicle access to the mine area and to control surface water runoff, a perimeter <br />road and embankment will be constructed along the proposed new permit boundary . This road will <br />run along the west and south sides of the property and will tie into 007 Pond embankment. A flat <br />bottom ditch with cross sectional area equal to a 10 feet wide trapezoidal ditch with 2:1 side slopes <br />and energy dissipaters will be constructed on the up dip toe of this perimeter road. This ditch will <br />be know as the 007 West Ditch and will collect and transfer all waterfrom the proposed permit area <br />to 007 Pond for treatment, see Map 2.05.3(3)-1. <br />There is one natural occurring drainage channel that 007 West Ditch must traverse to arrive at 007 <br />Pond. The drainage channel will be blocked by the perimeter road mentioned above. The roadway <br />will be constructed in compacted lifts and will be of sufficient height to contain the water in 007 west <br />Ditch and of sufficient height to allow water to rise to a height in the natural drainage channels to <br />continue its flows south and easterly toward 007 Pond . The diversion structure will store less than <br />20.0 Acre-feet and will not be utilized at this time for water quality treatment purposes but rather <br />to just divert water runoff to 007 Pond. WFC understands that some benefts exist from this <br />ponding action to allow sediment to settle out before discharging to Calamity Draw. WFC has <br />elected at this time to design 007 Pond to handle the entire duties of water quality and water <br />retention time. 007 Pond will continue to be the designated NPDES discharge point . <br />The perimeter road diversion structures, known as 007 Diversion Structure 1 (Map Att 2.05.3(3)-1, <br />will have two designed outlet structures as required by DMG. There will be a primary and <br />emergency spillway structure that will be of sufficient size to handle either the 10yr-24hr or 25yr- <br />• 24hr event. Atypical cross section can be seen in Map Att 2.05.3(3)-2. The computer program <br />SEDCAD + was used to model the area for surface water runoff and sediment deposition. A 10yr- <br />24hrand 25yr-24hr precipitation event was calculated and can be seen in this attachment. <br />007 East Ditch <br />The original 007 East Ditch was constructed at the start up of New Horizon Mine. It started out as <br />a single ditch that ran on the down dip side of 007 Pond Road and discharged into 007 Pond. Then <br />a second ditch was constructed on the up dip side of 007 Road and the water also flowed into 007 <br />Pond. WFC has since reclaimed 007 Road and a single 007 East Ditch was reconstructed to <br />proper size along the southeast disturbance line. Culvert C-102 was eliminated in the process of <br />reclaiming 007 Road and Culvert C-103 was retained but located in a different orientation. The <br />program SEDCAD was used in the original design of 007 Ditch. The same SEDCAD run can be <br />seen in this attachment. <br />Attachment 2.05.3(3)-1- 1 <br />