26 March 2012

Parkland Erosion Caused by Stormwater Project

On March 9th, while visiting in Elmwood Park, a severe condition of erosion was noticed near the bridge over Wood Creek. The slope southward of the "mosquito box" had erosion of several inches of soil in some places. Pictures were taken and sent to the City of Omaha Public Works Department that is responsible for the CSO! Project.

A meeting was held on site to discussion the situation on the 19th. The city representatives and the construction company foreman agreed that there was a problem. It was the result of water runoff from the street extending up the hill to the east.

Without any curb, the runoff was leaving the pavement and eroding the hill.

On the 19th, waddles were put in place to divert the runoff and to direct it westward.

Common sense would have meant that the project plans would have included a curb and a stormwater drain. They weren't included — due to inadequate consideration and lack of design attention to the matter — so now this problem occurred and will continue, especially during any heavy rain events. Diverting the runoff westward, as has been done, will only cause move the problem to another place, and cause erosion there.

There needs to be a curb installed and something put in place to properly handle any runoff.

Note the sediment that has accumulated at the stormwater construct (i.e., "mosquito box, because of permanent accumulation of standing water). Sediment barriers have been put in place to prevent any material from reaching Wood Creek. Any continuance of sediment runoff will increase the amount present. Any large rainfall event with any large amount of associated runoff would likely overwhelm the barriers.

The green shoots of vegetation now sprouting are a cover crop to stabilize the hillside until the permanent vegetation of warm season grasses get established. The species used included deep-rooted big bluestem and Indian grass.