Sheetflow Construction Erosion and Sediment Control

April 10, 2020

Dredge in the Fog-Terminal 117 Superfund Site

Photo: David Jenkins

Just a dredge in the fog, on the Duwamish Waterway, in Seattle, Washington, waiting to dredge up contaminated sediments at the T-117 EPA Superfund site in 2013.

April 9, 2020

Good Use of Silt Fence

Photo: David Jenkins

This silt fence is being installed to contain a five acre crushed concrete pile. It is trenched in, staked every six feet, has wire backing and uses zip ties to secure it to the stakes.

Crushed concrete from 16 Center Reconstruction Photo: David Jenkins
Crushed concrete from 16 Center reconstruction with silt fence. Photo: David Jenkins

April 8, 2020

Undercover Construction Inspector Vehicle

Photo: David Jenkins

This was my daily driver for several years, a 1988 Volvo 240 with over 300,000 miles on it. I sold it to an musician a few years ago. It was painted by Angelina Villalobos in South Park, Washington.

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!

April 3, 2020

Eroded Stockpile

Photo: David Jenkins

This stockpile is well within the project boundaries and there is nothing leaving the project. I consider this a problem for the contractor, not for water quality compliance. By allowing this to occur, the contractor has made the eroded stockpile soil unsuitable for use in embankment fill and has to haul it offsite at their expense. This could have been avoided by berming the top of the stockpile to direct water to pipe slope drain pipe that prevents water from flowing over the side of the fill.

April 2, 2020

Muddy Puddle Inside the Project

Photo: David Jenkins

Is this a problem if it is completely contained within a project boundary? Unless vehicles are driving through this and tracking mud outside of the project, I don’t consider it a problem and would only caution the contractor to watch out for trackout.

April 1, 2020

Compost Berm

Photo: David Jenkins

We rarely use silt fence on smaller airfield projects because: the work areas are nearly flat, are surrounded by grass or pavement, the work takes a few months, usually in the summer or fall. Compost berms are frequently used to: contain water, divert water, prevent site runoff. A secondary benefit is filtration; there is some turbidity reduction. Lastly, when done,. we spread the compost out over the disturbed soil and hydroseed it, enhancing grass growth and eliminating the waste of land-filling silt fence.

March 31, 2020

Straw Wattle on Slope Stops Rills

March 30, 2020

Before and After

Photo: David Jenkins
Photo: David Jenkins

The contractor had to connect a new storm system from up the hill into an existing catch basin in the foreground. After they completed the connection but before paving, they covered the pipe run with plastic and sand bags to protect from dirty water entering the catch basin. Work was completed during dry summer weather. Paving took place a couple of months later.

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