CCP 02-10-1992 - Laserfiche WebLink

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I .. If ponding is required in the wetland preservation area, the top of the I baffled weir can be raised to an elevation of 972.0. This elevation will still keep the high water level of the pond at elevation 972.8 because 22 I cfs will go over the top of the weir in 100 year 24 hour storm. The water in the pond will raise to an elevation of 971.3 before being treated by the I weir which will pond water app~oximately 1.8 feet deep. I The 24" RCP pipe will convey the stormwater runoff through approximately 450 I feet of pipe from the wetland preservation area to the low area north of Arden View Drive. The 24" RCP pipe will be centered within permanent and temporary I construction easements. The City of Arden Hills is currently in the process of I acquiring the permanent and temporary construction easements around pond A-7a and to install the storm sewer from the wetland preservation are to pond A-7a. .. Refer to page 5 at the end of this report, for a description and a drawing of the proposed permanent and temporary easements. This low area has been I designated by the North Central Drainage Report as the ponding area for the I entire 16.67 acre drainage area, labeled A-7. I Under current conditions the water level of pond A-7a is at elevation 945.3 with an overflow to the west at elevation 945.3 and a peak discharge from the North I Central Drainage Report of 4.8 cfs. The pond east of pond A-7a flows to a low I area that does not have an overflow to pond A-7a. Therefore, the flow that reaches pond A-7a is the area around pond A-7a and the flow being conveyed by I the 24" RC pipe. This amount of runoff, with a discharge out of pond A-7a through the existing channel of 4.8 cfs, requires a storage volume of 1.35 acre ~. feet for the 100 year 24 hour storm. The pond will rise to elevation 946.50, which is approximately 1 foot higher than the present pond level. A maximum I I __ ___u____n_______