By Thomas P. Healy
In June 2014 the U.S. Army Corps of Engineers (USACE) issued its final Record of Decision (ROD) and approved the Westfield Boulevard Flood Wall as the preferred option to complete its 300-year flood plain protection project with the City of Indianapolis.
While this concluded the multiyear formal federal decision process, the City of Indianapolis Department of Public Works (DPW) continues to meet with the Corps and the Federal Emergency Management Administration (FEMA) to select a floodwall option that provides maximum protection to the greatest number of residents.
The ROD also made recommendations for proposed tree-clearing actions that would complete the Phase 3A/Warfleigh and Phase 3C/Monon–Broad Ripple sections. The Corps rejected an option to leave conditions as they currently are and opted instead to require clearing of vegetation 15 feet from either the toe of the levee or the face of the floodwall.
According to the USACE, approximately 6.9 acres of vegetation along the Warfleigh segment will need to be removed along the White River for approximately 1,140 linear feet (or 15 percent of its total length), with erosion control blankets installed there. In the Broad Ripple section, approximately 0.62 acres will require clearing. A total of more than 7 acres of mature bottomland hardwood forest will be removed, and three wetland areas totaling 0.45 acres will be affected by vegetation removal.
To mitigate what it terms “unavoidable impacts,” the Corps will work with the City to plant similar bottomland hardwood tree species within the watershed in order to minimize impacts to the endangered Indiana bat. The area will cover approximately 81 acres. Few residents will live to see these seedlings mature to the height of the trees that are slated for removal.
“We know there will be consternation over vegetation management,” Michael Massonne, a DPW project manager, said. “This has been no secret. The Corps has made it clear that if vegetation is not removed the safety officer will not certify the project.” No certification means no removal from the flood plain and no elimination of the need to carry flood insurance.
He said the City continues to meet with FEMA to discuss possible options for certifying the completed parts of the levee under a FEMA initiative called Levee Analysis and Mapping Procedure (LAMP). The goal would be to obtain conditional certification that the existing levees remove certain Broad Ripple properties from the current 100-year flood plain.
According to Massonne, the City commissioned Christopher B. Burke Engineering to study possible alternatives along the west bank of the water supply canal for Phase B of the Indianapolis North Flood Damage Reduction Project.
The image above is an exhibit from the September 2013 Christopher B. Burke Engineering “White River Flood Protection Alternatives Feasibility Analysis.” Massonne said the exhibit is titled the “do nothing” alternative because it is a snapshot of the potential benefit provided by the currently completed structures if nothing more is constructed. He said the potential benefited areas are shown in pink. They are at higher elevations in the areas behind the levee.
Because the levee does not sit close to high ground, Massonne said that in the event of a 100-year event, floodwaters will still flow around the lower end of the structure and enter lower elevation areas (shown in blue) behind the existing levee. He said the exhibit is preliminary and will be detailed during the process of working with the Corps and FEMA to determine real benefit from the existing levee.
In September 2014, the City filed an application to implement the recommended vegetation management program with the Indiana Department of Natural Resources, which has jurisdiction over riverbanks in the state. In response to requests from the Friends of White River and other citizens, DNR scheduled a public hearing to discuss the proposal Thursday, Dec. 11 in the Parish Hall of St. Paul’s Episcopal Church, 6050 N. Meridian St.
A version of this article appeared in the December 2014/January 2015 issue of the magazine.