Laserfiche WebLink
Rationale for Recommendation to Approve <br /> Page ; 7 <br /> September 26, 2016 <br /> In this matter there is no requirement to differentiate between groundwater and surface water for <br /> DWR compliance purposes, only total quantity. Therefore, AM-01 demonstrates compliance <br /> with Section 34-32.5-116(4)(h) C.R.S., and Rule 3.1.6(1)(a). <br /> IL Comment that the spillway elevation of 5040.8 feet is 4.8 feet higher diau the <br /> elevation of the Orr drain outlet to the reservoir, and could lead to reverseJlows <br /> if/whent the reservoir is filled. (Equity Funding LLC--second comment period) <br /> The design high water elevation of the reservoir is 5036.0 feet. 5036.0 feet is also the design <br /> elevation of the Orr drain outlet, and the design elevation of the proposed reservoir drain <br /> structure, which will consist of three 24 inch diameter pipes, intended to convey flows from the <br /> Orr drain, and any other sources, from the reservoir back to the Platte River. Under normal <br /> operating conditions the elevation of the reservoir should never exceed 5036.0 feet and therefore <br /> reverse flow through the drain from the inlet, set at 5036.5 feet should not occur. <br /> During a major flood event which overwhelms the reservoir drain and causes the reservoir to <br /> exceed the design high water level, reverse flow through the drain is to be prevented by raising <br /> the drain inlet utilizing the elevation control "stop-blocks". <br /> The emergency pillway referred to in this comment was designed to meet the requirements of, <br /> and approved by, the Urban Drainage District. This emergency spillway structure is intended for <br /> use only as a failsafe during a major flood event to prevent head-cutting from flood flows from <br /> the reservoir back to the South Platte River, which could potentially lead to the failure of the pit <br /> wall and capture of the South Platte River. <br /> The elevation of the ground surface at MW-2, adjacent to the Orr property in the vicinity of the <br /> Orr drain, was surveyed at 5041.59' (0.79 feet higher than the spillway elevation). Because the <br /> spillway elevation is below the existing ground elevation of the Orr property in the vicinity of the <br /> drain inlet, the impact from any reverse flow from the drain structure, if it occurred, would be <br /> expected to be minimal and localized to the immediate excavated area of the drain inlet on the <br /> operator's property if the drain inlet is properly closed off. <br /> Conclusion <br /> Therefore, on September 26, 2016, the Office determined the application satisfied the <br /> requirements of Section 34-32.5-115(4) C.R.S., and issued its recommendation to approve AM- <br /> 01 to the Hazeltine Pit, Permit No. M-2004-031, over public objections. <br />