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2011-11-30_PERMIT FILE - C1981008 (2)
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2011-11-30_PERMIT FILE - C1981008 (2)
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Last modified
8/24/2016 4:45:30 PM
Creation date
12/20/2011 10:06:12 AM
Metadata
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Template:
DRMS Permit Index
Permit No
C1981008
IBM Index Class Name
Permit File
Doc Date
11/30/2011
Doc Name
Pond 013 As Built Sedcad & SurvCad Hydrology Calculations for 10yr-24hr & 25yr-24hr Events
Section_Exhibit Name
Section 2.05.3(3) Attachment 2.05.3(3)-21
Media Type
D
Archive
No
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of it passes through the Primary Spillway and the remaining, if necessary, goes through the <br />Emergency Spillway. <br />Sediment Pond 013 was designed to be both a passive flow thru and a manual operated pond. <br />Generally the permanent pool elevation will be at the lowest 0 -6 "diameter gate valve opening, <br />which will be initially set at 5552.00 elevation. One valve will be partially opened while the second <br />valve will normally be closed. The valve that is operational will be adjusted so that the pond will <br />be decanted or dewatered to the elevation of the lowest opening (the operational valve) in a 24hr <br />time frame. With this arrangement, the pond water retention time can controlled and monitored <br />so the NPDES water quality parameters can be met. The valve(s) will be periodically adjusted to <br />accommodate for the varying water quality coming off the ever changing vegetation covered <br />reclaimed fields. When the 10yr -24hr storm event enters the pond, the water will be allowed to <br />rise and if necessary, go through the Primary Structure but not through the Emergency Spillway. <br />After the storm event, the pond retains the water for several hours while the gate valve(s) slowly <br />dewater the pond. In the case of the 25yr -24hr event, the inflow of storm water will be allowed to <br />enter the pond, some of it will go through the gate valve(s), the Primary Spillway and the <br />remaining, if necessary, goes through the Emergency Spillway. <br />Sediment deposits within the pond will be allowed to accumulate to a pointwithin 0.5ft of the lowest <br />gate valves. When this occurs, then a 6" diameter pipe extension of approximate 1 -2ft will be <br />attached to the flanged valve body to raise the opening of the valve above the sediment bed. This <br />will then raise the point to which the sediment bed can accumulate too. It has been observed in <br />other ponds that sediment in the pond forms in a delta type fan starting from the bottom of the <br />pond inlet structures and goes toward the outlet. Even though SEDCAD and the LISLE equation <br />calculates the amount of sediment inflow and volume of such, the true sediment dispersion within <br />the pond will not be uniform. For that reason, the elevation difference between the pond bed load <br />and the valve opening will be monitored and periodically adjusted to keep adequate freeboard. <br />Clean out of the sediment will occur when the bed reaches to within two (2) feet of the Primary <br />Spillway Inlet. The SEDCAD4 program suggest that with an Average Annual R value that they <br />supply for the Nucla area, it will take approximately 6 -7 years for the pond to fill up to an elevation <br />of 5553.0 (2.0ft below the Primary Spillway). <br />Attachment 2.05.3(3) -21 -5 <br />
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