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Section 816.46 (u) Continued. <br />The detention time for each pond has been designed to be a minimum <br />of 24 hours, and longer if necessary, to meet the applicable effluent <br />limitations with respect to Total Suspended Solids. The detention <br />time, as used in the plans, is considered to be the time interval <br />between the centroid of the inflow hydrograph and the centroid of <br />the outflow hydrograph of the design event. Each outlet device <br />is sized to provide the proper discharge rate so that the detention <br />time meets the design criteria. Each pond has a unique inflow <br />hydrograph which is controlled by the hydrology of the upstream <br />watershed. The outflow hydrograph is established by the physical <br />design of the outlet device and can be variable. By selecting the <br />proper outflow hydrograph so that a detention time of at least 24 <br />hours is provided, the correct size of outlet device can be selected. <br />Each outlet device will have trash racks to prevent clogging. In <br />no instances is the elevation of the dewatering device located <br />below the elevation of the calculated maximum sediment storage _ <br />volume. Finally, all primary outlet structures have been designed <br />so that all outflow which occurs as a result of a 10-year, 24-hour <br />precipitation event passes through the primary outlet and that none <br />flows through the emergency spillway. <br />All ponds have been designed so that the minimum elevation at the <br />top of the settled embankment is at least 1.0 foot above the eleva- <br />tion of the water surface in the pond with the emergency spillway <br />flowing at design depth. Inspection of each cross section in the <br />plans will show that in all cases the freeboard is greater than 1.0 <br />foot. To allow for settling, the constructed height of the dam <br />will be at least 5 percent greater than the design height. During <br />construction, an onsite registered professional engineer will <br />assure that this is accomplished. Additionally, ponds will be <br />constructed primarily with clay, which, because of its high density, <br />will decrease the potential for settling. On large ponds, such as <br />pond A, each lift will be less than 10 inches and will be compacted <br />during construction to minimize settling. <br />Exhibit 8p 816-46 12/13/99 <br />