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I I I I I I I I I I I I I I I I I I 3 Drainageway Modifications The FEMA floodplain and floodway are based on 1973 conditions (the date of the aerial mapping used for the AS studies). Since that time, many changes have been made which impact the floodplain and floodway of the Poudre River at the WPCF. Some of the changes are: . The treatment facility was expanded in 1983 by the construction of a new administration and laboratory building, preliminary treatment facility, additional aeration basins and clarifiers, sludge pumping stations, disinfection building, and chlorine contact basins. . The anaerobic sludge digestion complex has been expanded. . New bridges have been constructed over the Poudre River at Ash Avenue and at 8th Street. . The Westem Sugar Company river diversion structure was constructed at the WPCF. Ferna Meetings BC held meetings with FEMA representatives during the course of the study to discuss project facts, physical constraints, analysis findings, and to receive guidance on regulatory procedures. Meetings were held on: · February 22 and Apri127, 1993 with John Liou, Hydraulics and Hydrology; and · June 15, 1993 with Virginia Motoyama, Chief, Flood Branch. The following pertinent project information was discussed: 1. Remodel of existing structures may be undertaken within the floodway if there are no negative impacts to the floodway and the remodel costs are less than 50 percent of the structure's present market value. 2. The COE has revised the hydrology for the Poudre River; however, the new hydrology has not been recognized by FEMA. 3. Any increas(~ in the size of a building footprint within the floodway will be interpreted by FEMA to have a negative impact on the floodway even if the model does 110t reflect a water surface rise. Mitigation, such as a reduction of the Mannings "n" value via relandscaping or paving, may be reqllired for acceptance. 21/7387