Sheetflow Erosion and Sediment Control

June 24, 2020

Silt Fence and Trackout Fail Part 2

This is a follow up to Silt Fence and Trackout Fail post from April 6, 2020. Same old !@#$, different month.

Photo: David Jenkins
Photo: David Jenkins

June 1, 2020

Lake Emelia in Port Orchard

Video: Kitsap Sun

This is what happens when the stormwater pond is an infiltration pond, undersized and covered with sediment so it doesn’t infiltrate. This was a 2 inch in 24 hour storm, or about a 2 year event, which should have been pretty easily contained if the pond had been designed as a temporary sediment pond for use during construction. Also, they should have had a construction stormwater treatment system set up to treat for turbidity. There really is no excuse for this. Poor planning.

April 7, 2020

Silt Fence Water Bars Fail

Photo: David Jenkins

Whenever I see something like this, it makes me think that the site owner/contractor either didn’t know what they were doing or bit off more project than they could chew, or both. These guys cleared, grubbed and graded something over 80 acres starting in late summer, failed to phase the work, failed to use soil cover practices, failed to listen to the experts and got nailed by the fall rains.

Erosion control is really about water control: reducing volume, preventing it from becoming turbid, and controlling where it goes. By the time the rains hit this project, there was too much water, it was too dirty, and there were too few options for controlling where it went.

In addition, they refused to set up a chitosan-enhanced sand filtration system to treat and discharge water; this left them no options and too much turbid water that had nowhere to go. As a result, they hammered a wetland, were fined heavily, and were shut down for months.

Silt fences are not meant to control water, convey water, filter water; they are designed to control eroded sediment. Ditches, berms (rock, gravel, triangular silt dikes, etc.) would have been better choices at this location. Not opening up so much area so late in the season would have been the best option. Their means and methods did not save them time or money.

April 6, 2020

Silt Fence and Trackout Fail

Photo: David Jenkins

Just minding my own business last Friday, driving from Fred Meyer to the UPS store and passed this project. Told my wife I have to get a photo, she says okay since she knows me and my habit of stopping to take TESC photos. Made a u turn at the Wal Mart, drove back a block and stopped in the middle of the street to get this shot.

There is so much wrong here, where do I start? Clearly, dirt is being tracked off of the project in the background as you can see the sediment build up in the curb line. Someone told someone to put something in the swale to keep dirt out. Someone installed this silt fence.

First off, silt fence needs to be trenched in and this just has a few rocks placed on the flap.

Second, they probably couldn’t trench this in anyway without tearing up the drainage swale.

Third, only two of the three curb cuts are backed by the silt fence.

Fourth, silt fence is a barrier, not a filter, and with the volume of water draining off the asphalt during a rain event, dirty water would just blow around and under the silt fence.

Conclusion, silt fence is never used in a water flow situation; it is only to contain eroded sediment from a sloped area. A better BMP here is a compost berm or something similar that would allow some water to pass but filter some sediment. Sand bags would work to keep everything out of the swale but then the dirty water would bypass to the next catch basin, which probably has a catch basin insert, which would collect sand and such but would not do anything for turbidity. So, what is the best BMP? Stop the !@#$ ing trackout in the first place!

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