Sheetflow Erosion & Sediment Control Heavy Civil Construction

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.

October 4, 2019

Broken Waterline

Broken 16 inch waterline. Fortunately, all of the muddy water was contained in a 72″ storm pipe with a valve. Water was then pumped to a Chitosan-enhanced Sand Filtration (CESF) system for treatment to 5 NTUs for discharge to a creek. Knowing this project was going to be constructed over several winter seasons, we specified the CESF system in the contract.
Photo: David Jenkins

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