2012-06-18_REVISION - C1981012 - Laserfiche WebLink

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Zach Tru'illo 2 - June 15 2012 43. No content has changed in the report, therefore, only the cover page will be supplied. 5. DRMS: NECC must provide a plan for controlling runoff, particularly energy dissipation, once it flows through ditch D49 and onto the Parks and Wildlife property. Also, a field inspection from early May 2012 reveals that the drainage culvert on CPW's property which would relieve the runoff from ditch D49 has been buried. Finally, the Division requests that NECC contact Colorado Parks and Wildlife (CPW) regarding the discharge point of ditch D49. NECC: A temporary use agreement has been submitted to CPW to address energy dissipation of D49 once it leaves NECC property. The plan includes extending D49 by approximately 60', plating it with 15" riprap and then discharging into a 36" culvert, C85. The proposed arrangement can be seen on Map -14 and ditch and culvert design shown on Tables 20 and 21, respectively. CPW approval will be submitted to DRMS once it is obtained. 6. DRMS: The ditch D49 SEDCAD printout is unclear. In the time of concentration details (page EXH19(22) -49), there are two times listed for SWS #2 for Structure #2: 0.055 hour and 0.377 hour. Please explain. It would be very useful (but not necessary) to provide a schematic and /or map showing structures, sub - watersheds, and flow paths for D49 and other ditches. NECC: There are two subwatersheds for Structure #2. One subwatershed is associated with the upland area, the other is associated with the disturbed area that is contributing flow to the channel. The large majority of the runoff in ditch D49 is from the upland area, however, there is a small portion of runoff that will be generated from the berm that will be constructed between D49 and the various portions of the collection ditch on the outslope of the waste pile. 7. DRMS: The location where ditch D49 would originate was inspected. Please provide more details on the design of the upper end of this ditch to determine if it is sufficient to prevent flow down the drainage from impacting the proposed DWDA. Additionally, it appears that the proposed location of ditch D49 pre - disturbance goes up- gradient at the upper section. Does NECC plan on cutting the slope back or cutting the ditch deep enough to allow flow down the drainage and into ditch D49? NECC: Please see new D49 Typical section on Map 14. A 10' wide by 4' high berm (minimum) will be constructed between D49 and the DWDA diversion ditch. At the beginning of D49 there is a 6' berm, plated with riprap which will provide adequate protection to keep the diversion ditch within its channel bank. There will be a small amount of cut in the middle section of D49 -2 %, and a small amount of fill at the beginning of D- 49 -2 %; but overall the channel section does not go upgradient.