We used to use silt fence when we did construction on the airfield. More and more we are using compost berms. The airfield grades are very small, maybe 20:1.
Compost berms can contain bare soil areas, filtering turbid water. When complete, we spread the compost and hydroseeded.
I am giving a presentation on Perimeter Controls: Non-standard Practices for Managing Water and Sediment today at noon. Go to Erosion and Sediment Control Association- British Columbia for information and to sign up. It’s only 10 bucks.
Description-Silt fence is not the only perimeter control BMP option. It is not the best option in many situations. In this presentation, I will discuss when silt fence makes sense, when it doesn’t, what other options are available.
The best way to get grass growing quickly is to use soil amendment. This is composted yard waste, spread three inches thick. It will be tilled in the top six to 12 inches, track-walked, then sprayed with bonded fiber matrix, seed and 100% nitrogen fertilizer. We get the added benefit of increased water infiltration, reducing our storm water discharge volume.
The bulk of the work will take place to the right of the silt fence. The grass will be removed and the area re-graded. The grass to the right of the construction fence will remain undisturbed. Some work will occur on the taxiway to the left of the tractor. Rather than use silt fence in this low risk area, compost berm will suffice. When done, the construction fence and stakes will be removed and re-used elsewhere and the compost will be spread out on the grass.
This eroded 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.
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.
The fence went over just like dominos. At least the compost berm stayed in place.
Is this silt fence necessary? Overlooking the fact that this silt fence installation needs some maintenance, I wonder if it was ever really needed in this location? The slope grades to the fence are minimal and not very long, and the roadside ditch line is graded so that water will drain away from the road.
This type of silt fence installation is appropriate at the base of long, steep slopes, or if there is risk of sediment travelling off site. Also, all of the materials used will likely be land filled and not reused, including the wire backing and the “T” posts.
If this were my site, I would have installed orange safety fence with steel “T” posts, maybe with a compost berm along the base, on the project side. The safety fence can be easily removed and reused later, and the compost could be raked into the ditch line and hydroseeded.
I shot this video to show the benefits of compost for establishing grass.
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