Pond bank stabilization
Pond bank stabilization
(OP)
(cross-posted to earthwork and storm forums)
I have two ponds in the center of a residential neighborhood that have slumping banks. The soil has eroded in 12" x 12" chunks in the steeper sections, and a more uniform erosion in the shallower sections. The side slopes of the pond range from 3:1 to 1:1.
A couple options I have been considering include filter fabric/rip rap along the pond perimeter (12" avg. diameter, with stone both above and below normal water surface level), and vegetative stabilization using permanent erosion control blankets and a seed mix that will withstand constant inundation of water.
The vegetative option seems attractive from a cost perspective (no need to get a truck in between buildings for stone install), but I worry that the root structure won't be deep enough and soil will erode underneath root level. Will the stone be sturdy enough, or will freeze-thaw action move the stone into the pond?
Thanks for your input.
I have two ponds in the center of a residential neighborhood that have slumping banks. The soil has eroded in 12" x 12" chunks in the steeper sections, and a more uniform erosion in the shallower sections. The side slopes of the pond range from 3:1 to 1:1.
A couple options I have been considering include filter fabric/rip rap along the pond perimeter (12" avg. diameter, with stone both above and below normal water surface level), and vegetative stabilization using permanent erosion control blankets and a seed mix that will withstand constant inundation of water.
The vegetative option seems attractive from a cost perspective (no need to get a truck in between buildings for stone install), but I worry that the root structure won't be deep enough and soil will erode underneath root level. Will the stone be sturdy enough, or will freeze-thaw action move the stone into the pond?
Thanks for your input.





RE: Pond bank stabilization
RE: Pond bank stabilization
Thanks for the response. The soils in the area are clay (Vergennes & Covington Clays) with a high water table. The ponds are permanent, excavated ponds (1 acre in surface area, about 9' deep). I have been led to believe from the original designer that bentonite was used as a pond liner.
There may be some opportunity to cut back the banks in the steeper sections, but in others it may not be feasible. I have proposed that the metal stand pipe that serves as storm control be cut down 12-18 inches so that the water level can drop and some work can be done below the water level with less mess.
I can see how the failures are due to wet clayey soils. Here in VT, we have had a very wet couple of years, and it has been in these past 2 years that the erosion has accelerated. Do you have any insight on the shallower slope erosion? Same mechanism as the steeper sections? In these areas, it looks uniform, the old perimeter fence is now 2 feet from the edge of the water.
RE: Pond bank stabilization
RE: Pond bank stabilization
The area doesn't seem a likely candidate for erosion: there isn't much overland flow to the pond (only about 100' feet), rooftops are guttered, and there's a good vegetative cover. All of the bare earth and slumping is by the water's edge, not on the pond's side slopes. Do you think there could still be some erosion at the water's edge from overland flow without any other signs uphill?
RE: Pond bank stabilization
If you cannot make the slopes flatter, you will need soil reinforcement or some sort of retaining structure.