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90 01109 18:37 ~ S 303 985 9947 SRK DENVER OS <br />BATTLE MOUNTAIN RESOURCES, SAN LUIS PROJECT <br />CMLRD ADEQUACY LETTER RESPONSES <br />Page 19 of 28 <br />b. The current ditch design calls for a minimum ditch depth of <br />2 ft. The design flow would result in a flow depth of 1.5 ft <br />for ditches constructed at a grade of 1.5 percent <br />c. The diversion ditch design should be amended ttr a 2.5 ft <br />minimum depth to allow for one-ft of freeboard during the <br />design storm event. The redesigned ditch has a maximum capacity <br />of 70 cfs at a flow depth of 2.5 ft. Detail 2 of Figure C-8 <br />has been revised. <br />d. Under conditions of design discharge, flow in the diversion <br />ditches is subcritical in nature with a maximum velocity of <br />3.9 fps (feet per seconds). Reseeding of the ditches is <br />expected to provide sufficient erosion protection <br />35. A small area without upiand runoff controi exists between the east <br />and south diversions. How will runoff from this small ridge area <br />above the tailings be handled? <br />RESPONSE: Runoff from this small area will be routed into the south and east <br />diversions and have been included in the drainage area designs. A <br />small V ditch (approximately two ft in depth) will extend along the <br />upper tailings road/berm which will carry these flows into the <br />respective diversions. These ditches were not included in the design <br />since the area and associated are very small. <br />In addition, should the ditch breach, the flows can be easily handled <br />within the tailings disposal area (and have been included in the PMF <br />inflow calculations). <br />36. On page D-6] of the originai permit application, the statement is <br />made that details of the erosion protection/runoff control for the <br />mill site area wiil be provided upon completion of the mill design. <br />Nave these been developed and, if not, what is the expected timing <br />of this submittal? <br />RESPONSE: Detailed designs for runoff at the mill site area are currently being <br />completed. These designs will be completed following final approval <br />of the pending amendment and will be submitted prior to commencing <br />mill construction. <br />