FLOOD08354 - Laserfiche WebLink

Home Browse Search

I I I I I I I I I I I I I I I I I I I commercial areas have either blocked or ignored historic drainage patterns and thus have created a flooding potiential during initial and major storn events, In the older dOl'.ntol'.n areas of Lafayette, local flooding is frequent due to an inadequate storml'.ater conveyance system. Much of the runoff from the 01 der Lafayette and Urban Drainage and Flood Control District for the purpose of developing the selected alternative and design contained in this Phase B report. Selection of Alternative Plan areas of Lafayette are conveyed by the Emma Street Ditch and the Burl ington In preparing possible alternatives for future flood control during the Phase A Ditch to a point I'.here the flol'.s are forced overland into agricultural areas. study it was necessary to consider the various possible improvements to the Scooe existing drainage facil ities and the need for new drainageway facil ities in 1 ight of the technical requirements of storm drainage pl anning contained in the During the course of our Phase A study, our I'.ork has included, but has not Storm Drainage Design and Technical Criteria developed for the City of necessarily been limited to the follol'.ing: Lafayette. The basic al ternatives for a major drainageway pl an have been 1. Coordination I'.ith various jurisdictions, including the preparation of material s for periodic reviel'.. developed using the Technical Criteria as a guide. 2. Reviel'. of investigations and studies prepared by others. 3. Reviel'. of existing storm drainage systems to determine their adequacy for conveying storml'.ater, 4. Estimation of 100-year future development condi tion fl ooded areas, 5. Determination and selection of a general solution for drainage problems along the drainagel'.ays, Briefly, the alternative plans developed in the Phase A study are summarized as fo llows: 1. Alternatives 1 and lA were developed so that drainage \\Quld follow historic paths, through historic drainage basins, and therefore no inter-basin transfer of flow \\Quld occur. Alternative 1 was planned to handle 100-year storm runoff, from all future developments which are reguired to limit 2-year and 100-year flows to their respective hi storic flow rates. Al ternative lA was pl anned to convey 100-year storm runoff, from all future developments which \\Quld not be reguired to maintain flows to historic levels. 6. Preparation of report summarizi ng the sel ected alternative recommendations and conclusions. The report is t.o included a discussion of results, data tabul ation, cost estimates and illustrative charts and maps for basinl'.ide drainagel'.ay planning. 2. Alternatives 2 and 2A were developed to handle 100-year and 10-year storm runoffs respectively, assuming consolidation of drainage basins, whereby future storm runoff is directed around areas of future potential flooding. Further, Alternative 2A assumes on-site detention to 1 imit 2-, 10- and lOO-year runoff to their respective historic 1 eve1 s. A Storm Drainage Design Technical Criteria I'.as al so prepared in conjunction I'.ith the Phase A alternative planning. The intent of this criteria is to provide gui dance in p1 anning drai nage for future development and to ensure consi stency in storm drainage design I'.ithin the jurisidiction of the City of Lafayette and surrounding ~ou1der County. The Technical Criteria I'.as used during Phase A 3. Alternative 3 was developed to handle 100-year storm runoff using a regional detention concept, and therefore e1 imination of onsite detention requirements for future developments were assumed. Alternative 3 was al so developed assuming drainage basin conso1 idation and flow diversion as in Alternatives 2 and 2A. portion of this study. The Technical Criteria has been accepted by the City of 2 3