A draft report of a $10 million flood-control plan to reconstruct the Birdland Park and Central Place levees and improve the downtown levee system will be available for public review at an open house Tuesday at the State Historical Building, 600 E. Locust St.

The feasibility study was initiated in 1999 by the city of Des Moines and U.S. Army Corps of Engineers to analyze ways to prevent persistent flooding problems along the Des Moines and Raccoon rivers and their tributaries. The recommendations made in the feasibility study would provide improved flood protection to more than 850 residential properties and 650 commercial and industrial properties along the rivers, where damages from thhe 500-year flood in 1993 exceeded $325 million.

Corps of Engineers study manager Steve Russell said the most pressing need identified in the study was improvement of the Birdland Park levee, which has deteriorated over the years due to tree growth. “This levee, although big and impressive, has some major structural flaws,” he said. “The levee is tall and narrow and full of trees, and during a flood, if one of those big trees started to become undermined, the root ball as the tree came over the levee would tear it apart and Birdland Park would become flooded.”

Most levees, including the one at Birdland Park, have been built over a period of years and many have their original foundations, made of things like refrigerators and “anything they could find to block water and then put dirt on,” Russell said. “What we need is good clay.”

The current Birdland Park levee was built in the 1950s, but a more crude flood-control system was in place before that. The proposed work in that area would involve reconstructing 7,700 feet of levee to the 500-year flood protection level and building a paved recreational trail on the levee connecting both Riverview and McHenry Parks with the Neal Smith Trail.

The proposal for the Central Place levee calls for the reconstruction of 5,900 feet of levee to the 500-year flood protection level

The study also recommends improvements to the downtown levee system. The plan recommends elimination of seven structures in the existing levee where roads and railroads cut through a levee, and improvements to 12 others, as well as development of 18 to 21 acres of open-water riparian and wetland habitat as part of an environmental mitigation plan.

According to the report, federally funded projects are not justified for levee improvements on the Raccoon River near the George Flagg Parkway area, the Des Moines Water Works levee, the West Des Moines levee, the Walnut Creek levee at Grand Avenue, the Four Mile Creek levee and the Leetown Creekway South levee on University Avenue.

To qualify for federal assistance, the work had to show a benefit-cost ratio of at least 1-to-1. The recommended plan’s benefit-cost ratio is 2.5-to-1. The average ratio for flood-control projects nationwide is 8-to-1, but “it’s a good ratio,” said Ron Fournier, a Corps of Engineers spokesman.

The Corps of Engineers recommendation does not guarantee federal funding, he said. Once the study is finalized, the next step after the public comment stage, the Corps headquarters office will determine whether to seek congressional authorization, probably in the 2007 federal fiscal year when the Water Resources Development Act comes up for renewal, Fournier said. Appropriations might not come until the 2008 federal fiscal year, he said.

If authorized and funded by Congress, the Corps would pick up $6.5 million of the costs and the remainder would be borne by the city of Des Moines.

A copy of the feasibility report can be downloaded at www.mvr.usace.army.mil/DesMoinesFP/Documents/Feasibility200505/. Copies are also available at the Public Library of Des Moines, the West Des Moines Public Library and Cowles Library at Drake University.

Tuesday’s open house in the Historical Building’s Classrooms A and B takes place from 2 to 9 p.m. Des Moines city and Corps of Engineers officials will be available for informal one-to-one discussions from 2 to 6 p.m., and a formal presentation of the study findings will begin at 6 p.m., followed by a question-and-answer period.