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I I I I I I I I I I I I I I I I I I I 000999 way for Cherry Creek based on a maximum rise of 1 foot in the water surface. This was submitted in conjunction with a Letter of Map Revison (LOMR) to revise the FEMA f100dpain to match the CORP floodplain. This work was provided to the CONSULTANT as basic data for use in the feasibility study (see Figure-7). The backwater analysis to define the flood profile was initiated at the upstream face of the Arapahoe Road bridge using the Corps of Engineers 100-year water surface elevation at this section. The 100-year flood peak is 49,490 cubic feet per second (Greiner, 1984). An analysis of the Corp of Engineers work by the CONSULTANT showed that the waterway opening for the bridge was improperly modelled. The actual waterway opening was found to be approximately 450 square feet larger. The CONSULTANT corrected the HEC-2 model and recomputed the back- water analysis. The analysis calculated the 100-year water surface upstream of Arapahoe Road was found to be 0.6-feet lower than the Corps of Engineers.at the bridge and tapering off to zero in approximately 2000 feet. This. difference was cons i dered ins i gnifi cant and the Grei ner Engi neeri ng Sc i ences, Inc. data was used in this study. The work by Greiner Engineering Sciences, Inc. also included a floodway analysis based on a maximum of 1/2-foot rise in the 100-year water surface (see Figure-7). The floodway was also based on equal conveyance encroachment into the floodplain on both sides of the Creek except for realignment of the f100d- way wi thi n the Ri ver Run project. The floodway work by Grei ner Engi neeri ng Sci ences, Inc. for the most part was al so used by the CONSULTANT. In areas where the f100dway line was drawn within the channel area, the line was moved to the top of the bank. A summary of the floodplain and floodway area by property owner is shown on Table-I. -8-