The story documents how the City and State are failing to enforce laws on erosion control, and why that harms the health of our lakes. The story is now available online here, and a video showing City inspector Tim Troester and resident David Thompson is available here.
City lowers the bar for erosion control
On the video, I found Tim Troester's explanation of where the City sets the bar for erosion control to be very informative. Here, in the video, he's referring to a project's Erosion Control Plan, which is frequently designed by City engineers:
"...[For] most plans the standard has been to design those erosion controls to the one- and two-year* rain events. Of course we have rainfall that exceeds these frequently, but it comes to a cost comparison, a cost effectiveness. We can always do more for erosion control, but at some point, it can end up costing more for the erosion control, than it does to redo a street or a project. And where that tradeoff is, is still to be debated."
The law--on which the EC Plan is based--makes no such excuse or exception for costs. It makes no exception for big or small rain events. So Madison has rewritten the law for its own convenience.
One thing I learned from following the Edgewood Av sediment spill of June 21, is that certain hilly sites, close to waterways, are much more prone to failure than others. So the "tradeoff" Tim speaks of ought to be adjusted for these difficult sites. Let's dig into some numbers.
How much does erosion control cost at a difficult site?
The Hillcrest Upland Greenway is due for construction starting Oct. 4. It presents a site more challenging than the Edgewood Av site because it's a narrow ravine emptying a basin half a mile long. So the Greenway project could be a good test to see whether, the way the City practices erosion control, costs are getting out of hand.
Tim Troester said: "...at some point, [erosion control] can end up costing more than it does [for] a project." Is that what's happening here?
I looked at the bid from the low-bidder for the project. The cost for erosion control measures during construction amounted to 7.4% of the total contract amount.**
Given that this is a difficult site, and that one of the reasons for this project is to control sediment from the ravine after the project is finished, 7.4 % does not look like a very high standard for erosion control.
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* A two-year rain event is defined as 2.9 inches in 24 hours.
** This figure included erosion control matting, which might be considered part of the post-construction planting, depending when it's applied. But the figure excludes planting of ground cover, planting of trees, or the riprapped channel, which amount to restoring the land surface to what it was before it was disturbed. Included in my total for "erosion control during construction" were items 21001, 20217, 21014, 21015, 21017, 21018, 21019, 50361, 90035, 90036, 90037, 90038, and 90039.