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Memorandum <br />July 31, 1997 <br />Page -2- <br /> <br />be 555' above mean sea level. The 1994 maps estimated that 100 year flood <br />elevation to be 558' above mean sea level. Since that area is relatively flat a three <br />foot change in flood elevation can affect a large horizontal distance. Based on <br />the flood plain area of the 1981 maps, very few lots would have required a <br />Certificate, but based on the 1994 maps any lot adjacent to Back Creek would <br />have. These same things are true in the Oaks Estates. <br /> <br />The elevation of floods may continue to increase as a result of development, <br />within the County and outside of it. A map of Mecklenburg County with <br />estimated rainfall is also attached. The area of the heaviest rainfall is below N.C. <br />Highway 49 in eastern Mecklenburg and includes the Back Creek basin. <br />Development within that basin, which increases impermeable surfaces, <br />combined with the heavy rainfall contributed to the flooding problems along <br />Back Creek in Cabarrus County. <br /> <br />One of the possible responses to flooding problems is to amend the Flood <br />Damage Prevention Ordinance. Property owners are currently allowed to use <br />fill or flood proof construction to elevate a building to two feet above the 100 <br />year flood elevation. Those regulations may be changed to no longer permit <br />construction in areas lower than the flood elevation plus two feet. This will <br />leave the natural flood plain unencumbered by buildings or fill and allow it to <br />function as a storage area for stormwater. This response would not, however, <br />protect buildings constructed outside that area should flood elevations increase. <br /> <br />The areas which are experiencing flood damage would require much more <br />extensive, and expensive, measures to alleviate the problems. Minor <br />improvements to the stream channels would probably not increase the storage <br />area enough to lessen flood damage. Some type of engineered sto~mwater <br />detention ponds would have to be constructed to have an appreciable effect on <br />flood elevations. This solution would be applicable to some streams, but is not <br />feasible for the largest volume flood areas such as the Rocky River. <br /> <br />Mike Byrd has prepared a map of areas in which road flooding occurred. He <br />has passed that on to the County Manager if you are interested in seeing. In <br />addition, we are compiling information of where property was flooded. <br /> <br />We hope this helps you to better understand how development is regulated in <br />areas of possible flooding. If you have additional questions or would like to <br />direct staff to make changes, please call me. <br /> <br />Attachments <br /> <br /> <br />