Sheet Flow Construction Erosion Control

December 9, 2020

Gravel Berm

While placing gravel base before paving, this contractor used the motor grader blade to create a berm along the edge. Eventually, they will blade the gravel to blend it into the edge of the asphalt. In the mean time, the berm will keep water that drains off the asphalt from eroding the soil on the left.

Presentation: David Jenkins-Sheetflow Erosion Control

September 25, 2020

Gravel Berm

Photo: David Jenkins

When we rebuilt this road, we had the contractor blade the gravel base course into a berm along the edge. This created a berm to project the bare area on the left from erosion caused by runoff from the roadway.

The gravel berm was bladed smooth just before installing a curb along the edge of the road. The bare soil was hydroseeded with bonded fiber matrix.

By using the gravel in this way, we avoided installing silt fence, preventing the soil disturbance that causes and keeping a bunch of plastic out of the landfill at the end of the project.

February 18, 2020

Gravel Borrow

Just add water. Photo: David Jenkins

Funny thing, when wet, gravel borrow is like quick sand. When dry and compacted to 95%, it is hard as a rock and will not infiltrate water.

December 23, 2021

Catch Basin Protection

Title: Down the Drain-Catch Basin Protection

Topic: How do you project a catch basin during construction? Is a catch basin insert enough? What are you trying to protect it from-sediment, turbidity, gravel? How to you protect non-standard catch basins, slot drains, curb drains? What about covering them to keep everything out? Should you use plugs in the storm pipe? These and other questions will be discussed in this brief overview of catch basin protection.

Speaker: Dave Jenkins, CPESC, has over 25 years experience in heavy civil, public works construction as an erosion control and stormwater engineer, resident engineer, and construction inspector. He is trying to retire, but feels the need to keep going back to work and is closing out a habitat restoration project for the Port of Seattle.

Date: 2021 December 20, 12:15 to12:45pm

Organization: Pacific Northwest Chapter-International Erosion Control Association Website: http://www.pnwcieca.org/

December 18, 2020

Prepare for Fall and Winter Rains by Preventing Erosion

This is a blast from the past. I think I wrote this in 1996 with I was the first State-wide Erosion Control Coordinator at the Washington State Dept. of Transportation.

Preventing erosion is the best preparation.  Here are some things to consider when you prepare for fall and winter rains:

Cover bare soil. Final grades can be covered with hydroseed, erosion blankets, topsoil, bark or whatever final cover is planned for the project.

Get your hydroseed contractor lined up now and avoid the October rush.

Don’t open up more than a few acres after September 1st.

Grades that aren’t being actively worked can be covered with straw at a rate of 3000 pounds per acre. This is a very cheap and effective way to protect bare soil from raindrop impacts and erosion. Hand seed before spreading the straw. Spray it with water to help hold it in place.

Track your slopes with a Cat: up and down slope, not across slope. The first helps prevent erosion, the second speeds it up.

Use flex pipe drains at bridge ends if your permanent drainage system and curbs are not in place. Collect the water from the bridge using sand bags and divert it to the pipe. Make sure the pipe is long enough to reach the bottom of the slope.

Another good way to prepare for fall and winter rains is to use a water truck and water seeded areas weekly to get quicker growth. The better the growth going into winter the better.

If you have to open up a large area, only clear and grub small areas. You can clear larger areas if you don’t grub. Roots and slash help protect the bare soil.

Walk the site looking only at erosion controls, thinking ahead of areas that could have a problem. Identify them and start making additions and corrections.

Locate all existing water flows in and around your project and find out where they drain to.

Think about maintenance and regular inspection of erosion controls. When are silt fences going to be inspected and who does it? Who removes mud from check dams? Who covers slopes with straw or other mulch?

Get materials on site now. Again beat the rush for materials in October and November when everyone is in a panic to get plastic and straw. Stockpile enough straw, plastic, silt fence, flex pipe, sand bags, seed, rock, now to cover all areas that are bare.

Set up emergency procedures now. Who should be called in emergencies? Do you have a Certified Erosion and Sediment Control Lead (CESCL)? Brief your personnel on what to do if they see muddy water and who to go to.
Make sure that erosion control material installers know proper installation methods.

Make sure all your silt fence is installed on contour with the ends flared up slope a few feet. If it is not on contour, identify the lowest points of the fence as these will be the failure spots. Install a double row of silt fence at these low spots before you have a failure. Double up your silt fence in areas where eroding slopes could flow into wetlands or streams.

Do you have bare spots where previous seeding hasn’t grown? Cover it with seed and straw if the area is small, remobilize the hydroseeder for larger areas.

Make sure all catch basins within the project boundary are protected with inserts, fence surrounds, or other methods to keep mud out. Locate any catchbasins outside project boundaries that may receive water from your site and protect them.

Make sure that you have a copy of the  Temporary Erosion and Sediment Control plan (TESC) and any grading or environmental permits on site in the job shack. Know what they say. Give each inspector a copy of the TESC to keep in their truck. These are working copies that can be adapted to site conditions.

Modify your permanent stormwater ponds into temporary sediment ponds by installing a standpipe and blocking the outlet with sand bags. Cut a few small holes in the standpipe to allow for slow release of water. You can also use perforated pipe as the standpipe and hold it in place with “T” posts, wire, and gravel piled up around it.

Use geotextile fabric as a temporary ditch lining to protect bare soil from erosion. Hold the fabric in place with rock check dams, wooden stakes, or sand bags.

Make sure that all check dams are installed so that the top center point is lower than the bottom end points. This prevents end-cutting. You may have to add more material to the dam to increase the width, especially on wide ditches with shallow grade side slopes.

Now you know how to prepare for fall and winter rains: Prevent Erosion

December 8, 2020

Curb and Gutter Berms

I encourage contractors to install curb and gutters to function as berms, as soon as possible. This contractor also installed the first lift of asphalt over gravel base course to provide a stable work surface. This provides a clean work surface and prevents sediment trackout. The projects shown are the SeaTac FAA Tracon facility and the SeaTac South Terminal Expansion Project.

Presentation: David Jenkins-Sheetflow Erosion Control

November 17, 2020

Silt Fence Here?

Photo: David Jenkins

Would I put silt fence here? I would not. The work involves installing an 8 inch ductile water line to a property up the hill. The connection to service is at the left orange cone. The other orange cones are located on the backfilled excavation. I would have specified a gravel berm, asphalt berm, burlap fence, orange construction fence, or a combination.

September 27, 2020

Erosion Control Photos

Filed under: — Sheetflow @ 3:49 pm

All photos may be used for teaching and training purposes with attribution to: David Jenkins, sheetflow.com

Photos may not be used for commercial purposes without prior express permission from David Jenkins, sheetflow.com

May 27, 2020

Preventable Trackout

Photo: David Jenkins

This trackout was preventable. Asphalt was removed by the contractor to work on the new building foundation; the driveway asphalt was left in place, which is good. Gravel base course was delivered to be placed under the concrete slab.

Instead of backing all of the way into the site, over wet dirt, the trucks could have stayed on the asphalt driveway to unload. Site equipment could have been used to move the gravel.

The contractor could also have dumped gravel next to the asphalt, then graded it back into the site to provide a construction access into the site. In this way, the delivery truck could have stayed on gravel rather than driving on dirt.

While this is not a lot of dirt on the road, it does add up and is a magnet for inspectors and regulators to visit the site.

May 26, 2020

Dead End Silt Fence Installation

Photo: David jenkins

This location and poor silt fence installation makes no sense. I would have had the contractor install the silt fence to the temporary fence.

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