Erosion control plan for the Greenway--a critique

Since the ravine drains a basin above it, there is much more potential for erosion during a big storm, compared to the Edgewood Av construction site pictured below. The issue of planning for a big storm is what I want to discuss here.

I find that the plan is workable for light rain events, but completely inadequate for a large rainstorm (say over 1.75 inches). When I made this point in an exchange of emails, Lisa Coleman chose to ignore it. Based on this lack of reply, plus statements from Engineering staff, I believe the City has a policy of not designing for large storms, so as to keep costs to contractors (and hence the City) lower.

The City and contractors would rather pay for the additional gravel or soil to fill in the gullies--after a big storm happens--than pay for more robust erosion control measures.

Since most of the damage to the lakes occurs during large storms, I believe this policy can't be defended--since surveys show citizens are unhappy with the City's care for the lakes.

L. Mendota after large storm, late 1960s, by UW Engineering Dept.

Out of one side of their mouth, Engineering staff (and the Board of Public Works) say to people concerned about the lakes that they are trying like crazy to meet the 2013 mandated reduction by 40% of sediment to the lakes.  They told us at neighborhood meetings that "erosion control" was one of the two main reasons for the project.

But out of the other side of the mouth, they are saying to contractors: "It's OK to dump truckloads of sediment into the lakes when your erosion controls fail in a big storm. It just slips down the drain while people hunker down indoors. No one will notice."

This approach is so consistent that it must be policy. Who set this policy? Who will support it, once brought out of the closet?

It does seem a little wasteful to build elaborate erosion control measures, which just have to be dismantled when the construction is over. That's why I have advocated settling basins, rain gardens, and other watershed improvements, to be installed before a construction project begins. These erosion control measures will remain after construction is finished, to beautify the city and moderate future flooding.

You can read the full details of the erosion control plan, plus my critique, here.