Creek stabilization project to relieve flash flooding
A stream rehabilitation project in Maryland Heights, Mo., is the first part of an erosion control program that promises to relieve flash flooding and property damage and ensure better water quality in the community. The project involves the Fee Fee Creek watershed, a predominantly urban 14.6-square-mile area that has grown significantly in the last few decades.
Fee Fee Creek has suffered from development and the dumping of yard waste, construction debris and trash. In 1995, a series of landslides along Midland Creek, a branch of the Fee Fee, threatened to close the access road to one of the city’s park expansion projects and prompted Maryland Heights to look for a solution to the erosion problem.
The proximity of Vago Park to the creek induced Maryland Heights to look for alternatives to concrete banks. The city hired Jacksonville, Fla.-based engineering firm Harland Bartholomew & Associates to develop a stabilization plan for the creek. The city’s stormwater consultant, St. Louis-based Horner & Shifrin, was added to the team. The project incorporated two goals: * stabilizing the streambank adjacent to a portion of the access road; and * incorporating biostabilization methods to reduce erosion along 3,500 feet of the creek adjacent to the park.
The project was one of the first in the area to employ biostabilization, which capitalizes on the ability of plants to control streambed erosion. Native vegetation, used to stabilize the soil, also enhances the stream’s natural appearance.
The Midland Creek project encompassed about 700 feet along the west bank of the creek. From north to south, there were about 65 feet of existing riprap, 170 feet of gabion walls, 160 feet of lightly wooded slope, and 320 feet of concrete rubble and lightly wooded slope. The bank averages 25 feet in height, and there is a main sanitary sewer trunk line running about 4 feet below the bank in the creek bed.
Existing site conditions and flow regimes determined the method used to stabilize each reach of the bank. The area of riprap and gabions appeared relatively stable, and no modifications for slope stability were recommended. Slumps along the lightly wooded slope beyond the gabions were secured with a composite revetment of large rock mixed with vegetation.
The area that contained the concrete rubble was stabilized by constructing a living cribwall about 5 feet high at the creek bed, removing or burying the rubble, and regrading the remaining slope. Regraded areas were stabilized with an erosion blanket and native shrubs, trees, grasses and wildflowers.
Two citizens’ advisory committees are helping the city with the stabilization program, and a comprehensive educational program has been implemented to inform residents about the project. A complete technical description of the Midland Creek project is available on the city’s web site at www.marylandheights.com.