Sheetflow Erosion and Sediment Control

July 1, 2020

Debris Stockpile

Photo: David Jenkins

I like how the contractor built a contained area to temporarily stockpile removed asphalt and other construction debris. They used jersey barriers with cold mix asphalt along the base to contain the debris and rainwater.

June 17, 2020

Silt Fence Overlap

Photo: David Jenkins
Photo: David Jenkins

This silt fence surrounds a compost (Groco) stockpile, most of which will be used over the next several months. I don’t expect any runoff; this is a very low risk situation. Being low risk, i am okay with how the fence ends were joined. The orange fence ends overlap about 3 or 4 feet. The black is placed at the overlap seam, with about 3 or 4 feet of black fence on either side of the seam. The fence flaps are trenched in and covered with soil.

If this were a high risk situation, I would have required the contractor to use one continuous orange fence with no seams. Another option is to wrap the fence ends several times around a post and drive the post in. this effectively makes the fence one continuous installation.

June 11, 2020

Phasing a Stockpile Project to Prevent Dirty Runoff From Draining to Wetlands

Phase 1-

(A) Install silt fences on perimeter and at base of future stockpile.

(B) Clear, grub, grade, construct drainage ditches and temporary stormwater pond including outlet structure and perforated pipe level spreader drains. Grade to drain water away from outer perimeter silt fence and toward ditch.

(C) Hydroseed and install blankets in ditch line.

(D) NOTE: Background stockpile, built later, used an early generation construction stormwater treatment system and discharged to creek instead of level spreaders into vegetation.

Phase 2-

(A) Place and compact fill material to approximately 20 feet of vertical elevation.

(B) Trackwalk and hydroseed slope.

Phase 3-

(A) Same as Phase 2.

(B) Same as Phase 2.

Phase 4-

(A) Place and compact fill material to approximately 20 feet of vertical elevation. Start base of slope 15 feet in from lower fill and grade to drain away from lower slope and to the stormwater pond.

(B) Trackwalk and hydroseed slope.

(C) No hydroseed on top of the pile as material is continually brought in as available.

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.

October 30, 2019

Open Catch Basin Fixed Again

Back where we started, 30 mil PVC blocking the catch basin. Photo: David Jenkins

As of two days ago, there is new 30 mil PVC under the catch basin grate and turbid water is not draining into the catch basin. The contractor told their staff not to puncture the PVC. No word on whether they are thinking more proactively about this. The best measure is to keep the stockpile covered and the area cleaned up. We shall see what’s next.

October 27, 2019

Open Catch Basin

I found this open catch basin during a construction erosion inspection. The turbidity of the water draining into it from the stockpile measured at over 600 NTUs. Note that there is an insert in the catch basin; these do nothing to reduce turbidity. I notified the contractor who should have found this in their daily inspections, which I pointed out to them.

September 20, 2019

An Excellent Stockpile

September 17, 2019

Can’t Get Away From It

It doesn’t matter where I go, I always see some type of construction erosion issue. I went to visit relatives in Portland, Maine, flying in and out of Boston Logan International. In the terminal, waiting for my flight back home, I saw a construction project on the ramp; it had rained a few says before, hard. Obviously, the stockpile had not been covered before the storm and sediment washed off the pile into the drain.

I work at an airport that operates under strict turbidity effluent limits; here is how we do this kind of work:

(1) rarely do we allow stockpiles on the ramp because we rarely reuse the excavated material (it is either contaminated, unsuitable or doesn’t meet current FAA requirements); it is direct loaded into trucks and hauled off. When we do stockpile, we place dirt on plastic and cover it with plastic, using lots of sand bags to secure it from jet blast and wind.

(2) work areas are always isolated so there is no runoff from the site. Normally, we use four-inch extruded asphalt curbing along the base of the jersey barriers. Rolled hot mix asphalt (HMA) is used at the entrance point so water is contained but vehicles can access the site.  Water that builds up inside the curbing is pumped back into the excavation if clean, or a tank if contaminated.

I should have mentioned that we also have strict sediment trackout requirements: no visible sediment leaves the site at any time.  This is both because of the effluent limits and for safety reasons; dirt and debris that gets sucked up into a jet engine is damaging and possibly deadly.

Lastly, I am not casting aspersions on the folks at Logan; I don’t know their situation, permits, drainage system, or tolerance for risk.  Because of my situation, I have low risk tolerance for potential non-compliance with our permit and I notice when something would cause me grief at my airport.

August 27, 2019

Denver Dirt Pile

Just a nice dirt pile in Denver. Walking around between presentations at the International Erosion Control Conference in February 2019 and saw this. A little utility work in the street, going to reuse the excavated dirt, placed it on plastic, put some berms around base, no rain in the forecast and the dire goes back in the hole later in the day so no need for cover.

July 26, 2019

Down the Drain it Goes

Photo: David Jenkins

Then the sediment washing off of the uncovered stockpile drains into a catch basin which drains into a small salmon stream.

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