Design Memorandum with Environmental Assessment for Raccoon River and WalnutCreek, West Des Moines and Des Moines, Iowa Local Flood Protection Project. Revision

摘要

A flood protection project for the cities of West Des Moines and Des Moines,Iowa, was authorized by the Water Resources Development Act of 1986. The project consists of a series of levees and floodwalls that protect portions of the cities of West Des Moines and Des Moines, Iowa. The project will provide 100-year protection from Walnut Creek and the Racoon River. The levees will be constructed of semi-compacted impervious material with a 10 foot top width. Concrete floodwalls will be utilized where sufficient right-of-way does not exist to construct earthen levees. Several closure structures will be constructed across existing railroads and streets. The primary purpose of the project is to reduce damages caused by flooding along Walnut Creek and the Racoon River. The report includes the views of local interests as well as the technical analysis for hydrology (including rainfall events, runoff and watersheds) and hydraulics, geotechnical (i.e. soils and soil structure interactions) and structural mechanics. A detailed cost estimate, an economic analysis, and an environmental assessment as well as other subjects are covered in the appendices of this report.