Rules and the Erosion Control Plan

I was talking to a friend recently over lunch-- he's an urban planning consultant, so I always value his insights.

I explained to him how this blog tends to focus on the outcome of erosion control--whether or not mud is getting into the lake.  After a bit of hesitation, he said he really didn't agree with that approach--that erosion control practices have to be based on rules and regulations.

His critique forced me to think more about the rules.   Yes, I believe in the rule of law.  And yes, workers on a complex construction site need simple but definite directions to guide them.  We have plenty of rules now, yet despite the rules, too much mud goes into the lake after every storm.  Why is that?

The question about why the present system isn't working, and how we can make it better, is really the central mission of this blog.

So far, I've identified 30 kinds of failure.  Each one alone isn't so bad.  But when you add many together, the system fails to protect the lakes. 

Obviously, you want to look for the flawed procedure that has the biggest contribution, or is the easiest to fix.  I have a few candidates:

The Erosion Control Plan (EC Plan)

I've looked at some of these now, in detail, and find them very, very inadequate.  They are done as a trivial afterthought to the painstaking design of a project.  They neglect the most basic considerations, such as the amount of runoff entering the site from above it.

Weather is the cause of erosion.  Big weather is the cause of big erosion.  So effective EC plans must accommodate big storms.  Yet some EC plans produced by the City of Madison do not seek to accommodate even moderate storms.   Yes, I agree there's the possible 1000 year storm that no plan can accommodate.  But let's set the bar a lot higher than it is now.

The Best Management Practice (BMP)

Together, a number of BMPs approved by the DNR and published in a manual make up the "toolkit" of the EC plan designer.

Unfortunately, a number of these BMPs are very dull tools indeed. 

Let's take the example of the filter used at stormwater inlets.  It's made of filter fabric stretched across the opening, or hanging inside like a bag.  This is probably the most common tool, almost universal.  That's because they are cheap, easy to install, and easy to forget.

But observation of them in the rain indicates marginal effectiveness.

• Frequently filters are clogged, or flaps of excess fabric have blown over the entrance.  So a large percentage of water headed for them just goes on past, to the next stormwater inlet (which is probably unprotected).
• Sometimes the filters are ripped on installed incorrectly, so unfiltered water gets past them into the opening.
• The filters can only trap the larger particles--tiny particles of mud go right through.  Since the great majority of pollution is attached to the small particles, inlet filters can stop only a small fraction of the pollution leaving a construction site.

Stormwater inlet with filter, 7/7.  This is one of the few filters for a large project by Findorff.  Left: You can see it is clogged, and passing sediment downstream to the right.  Right: Enlarged, you can see the same filter has been clogged for so long that weeds are growing. Click to enlarge.

Another BMP is the gravel tracking pad.  The purpose is to prevent muddy tracks from leaving the site.  These are supposed to be 50 feet long, but almost never are that long.  At many sites, they have sunk into the mud, so they are no longer working.

Washing of tires (of vehicles leaving a site) is another BMP designed to address the same problem as gravel tracking pads.  But tires washing isn't practiced in Madison.  If I mention "tire washing," contractors and EC inspectors fall silent, as if I had done something very rude.  It's their worst fear.  Yet there it is, an approved and effective tool that no one uses.

My conclusion--our rule-based erosion control depends on the Erosion Control Plan, which consists of BMPs.  If both are fundamentally flawed, then the system of rules simply can't work.  That's why I have been forced to look at mud that's flowing out of a contractor's site.  But I do feel an obligation to help get the rules back on track.

So I'm going to be more "constructive" in the future by offering some analyses of current construction sites, and offering some "tips" on erosion control practices.  The "Miss Manners" of mud. 

More effective BMPs

We have to adopt more effective filters.  The only really effective filter is a large, natural one that includes vegetation--a settling pond or basin, a rain garden, or vegetated swale.  These will be far more effective than an artificial one because they will trap all sizes of particles, and return the water to the ground; meanwhile their biological activity will help to neutralize pollutants.

Granted, these will be difficult to achieve on cramped sites.  But it should be relatively easy to export dirty runoff to the natural filters we build within a block or two.  Construction of these natural filters should planned as an integral part of the main project--and then put in place before the main project begins.

More effective EC plans

• Put a lot more effort into them.
• Creative, based on the unique features of the site
• Able to handle major storms
• Rely on natural filters rather than on ineffective fabric filters
• Integrated EC--Erosion control design is part of the main project design (more on this later)
• Contractor should be selected in part for their ability to carry out a good EC plan.(In the Hillcrest-Upland Greenway, S&L Underground & Trucking bid $500 on a very complex "Stormwater Control" line item.  Clearly they haven't thought this out.

Years of debate

For decades, government committees and citizens have debated the problem of construction site erosion.  Periodically, they issue reports that say "Crack down on construction site erosion."  "Enforce the rules at construction sites."  But there hasn't been enough improvement.  I do acknowledge that controlling erosion on construction sites isn't an easy job.  If it were, the problem would have been solved by now.

This means that construction sites are one of the last industries that are still casting their garbage into the public commons.... our lakes and streams.   Cracking down isn't enough (though it would help).  An overhaul is needed.