Colorado Springs: North Douglas Creek detention designed to keep stormwater out of neighborhoods

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From The Colorado Springs Gazette (Matt Steiner):

Tim Mitros, the stormwater manager for the City of Colorado Springs, showed off the latest flood mitigation project Wednesday, unveiling a large sediment detention basin along North Douglas Creek that should keep tons of water, mud and bigger debris from invading residential areas.

The basin will hold about 25,000 cubic yards of sediment and can be cleaned out after each torrential storm, Mitros said. The new pond replaces a series of five smaller basins that filled quickly in early September 2013 after torrential rains pounded the Waldo Canyon fire burn scar and the rest of the Front Range from El Paso County to the Wyoming border.

“It was supposed to be a 10-year fix,” Mitros said, noting that the city was surprised at how quickly the smaller basins filled and knew it had to come up with a Plan-B.

Now when water and debris come raging down North Douglas Creek the large pond should stop most of the flow. And an “alluvial fan” below the basin will likely slow the water and spread out the rest of the torrent before it reaches the city’s storm sewers, Mitros said.

Mitros and Flying W Ranch Foundation executive director Aaron Winter are relieved that the project has been completed before the 2014 monsoon season and potential heavy thunderstorms hit the burn scar. Storms in early July, mid-August and September of 2013 threatened North Douglas Creek and left Manitou Springs cleaning up after flash floods poured over U.S. Highway 24, out of Williams Canyon, destroyed multiple homes and flooded businesses along Manitou Avenue.

“There is a lot of debris that is staging in the upper parts of North Douglas Creek,” Mitros said. “We expect in larger storms that the debris will start to flush out.”

According to the city official, an estimated 60,000 to 100,000 cubic yards of mud and debris are sitting along the creek less than a mile above the new detention basin. He said it took just about 60,000 cubic yards to fill the five smaller ponds.

Winter said the work that the city has done, as well as other projects by volunteers with the Coalition for the Upper South Platte, have helped reassure the foundation that its neighbors to the east will be protected.

“Knowing that this basin is in place to protect the homes downstream is a big weight off our shoulders,” he said.

More stormwater coverage here.

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