Laserfiche WebLink
I <br />! <br /> <br />Due to recent Changes in the law regarding wetlands, there will <br /> <br />be a far greater area of ponding available.for the City's <br /> <br /> Ultimate Drainage System than originally planned., for in the <br /> City's Comprehensive Drainage Plan. Therefore, by restriCting <br />I the outlet flow from the ponding areas,' the downstream pipe sizes <br /> <br />I <br />I <br />I <br /> <br />can be substantially decreased from those proposed in the City's <br />Comprehensive Drainage Plan. <br /> <br />Currently, a majority of the area in this drainage district does <br />not have an outlet to the Mississippi River. Due to recent heavy <br /> <br />I <br />I <br />I <br /> <br />rains during the fall of 1985, the groundwater and pond levels <br />have risen to intolerable levels. Flooding occurred along U.S. <br />Highway 10 and north of 149th Avenue N.W. causing substantial <br />property damage. To reduce pond levels and groundwater levels to <br />tolerable levels, a direct outlet to the Mississippi River will <br /> <br />I <br />I <br />I <br /> <br />be required. <br /> <br />III. DESIGN CONSIDERATIONs <br /> <br /> In designing the proposed facilities, the Soil Conservation <br /> Service (SCS) method of determining total runoff nd peak rates of <br /> <br />I <br />I <br />I <br /> <br />runoff was utilized. A 100 year frequency storm was used in <br />determining ponding areas. The entire drainage district was <br />analyzed using an IBM Personal Computer and the SCS 24-hour Type <br />II Rainfall Program and the SCS Hydrograph Technique.' <br /> <br />I <br />I <br /> <br />2 <br /> <br /> <br />