Pond Boss Forums POND CONSTRUCTION Building a dam Wall blocks + inexperience + erosion = frustration

Hello Folks,

My first post here. Really like the site so far. Just what I needed. So, here's my tale of woe. I have three ponds that were built, oh, maybe in the late 1960's. The water source is a very tiny rill that flows down from a nearby (Pocono) "mountain". The biggest pond, aptly named "Big Pond" flows into "Mystery Pond". When I bought the place there was a primitive spillway connecting the two. There was also a small stream bed flowing from a side of Big Pond that I believe is the original route of the rill. During heavy rains, the spillway became a rapids and the pond wall separating the two ponds was rapidly deteriorating. So, I had a monster load of coarse stone delivered and hauled it into the spillway, effectively closing it. Now the little side stream bed took the flow of water. That all worded just fine.

Next, I built a pond wall of those 26lb. interlocking wall blocks that you get at the big box stores. I set the first row into the mud at the pond edge and then dug out (by hand) the goo from the bottom of Mystery Pond to chuck over my new wall. Over that summer, the wall rose to be 6 blocks high. It was magnificent. I was certain it would outlive me and be viewed upon by future generations as marvelous as the pyramids. However...

It lasted about 2 years and then erosion and weather began to take its toll. Even tho' the wall blocks interconnect at the back making each ascending block an inch behind the one under it, the wall collapsed forward into Mystery Pond. Each successive rain event caused the wall to lean ever more precariously forward until the inevitable happened. The wall began to collapse into the pond.

So, after that long-winded explanation, my question to you, my ponding mentors, is how to I re-erect the pond wall? What do I lay in place under the first row of wall blocks to prevent its sinking into the goo of the pond? My pond is inaccessible to all heavy equipment as the area is thickly forested, so a primitive hand-hauled solution is required.

Interestingly the goo that I chucked over the wall while it was under construction has retained the shape of the original wall and has NOT eroded. ANY advice would be very welcomed.

Questions for you... and welcome to Pond Boss.

Does this wall no longer act as a spillway getting water over it from the big pond? This would make a big difference as to how its built.

You got a load of heavy stone delivered. Did you get that truck to this wall area?

Your wall needs 2 things to ascend into eternity, a concrete footing and drains to let the let the water drain out. The footing needs to be 16" wide and the drains can be 4" pipe and they need to be covered with gravel and landscape fabric. This will stop the drains from stopping up.I like your sense of humor.

I'm with kenc. Without a proper footer, and a way to relieve the pressure against the wall, it will eventually move. Also, did you just make a straight wall, or did you curve the wall back into solid dirt on each end? I realize than retaining wall blocks are stepped and overlapped, but having "wings" to tie the wall back into solid dirt would probably help also.

The type of fill used behind the wall will also play a role, (and this ties in with the drainage issue kenc mentioned)..ideally, you would want your fill to be at least level, or preferably slightly taller than the top of the wall. This will encourage water to run over and around the wall, rather than soak down in behind it, creating hydraulic pressure. Did you "cap" the pond muck with topsoil and reseed?

kenc started it, sprkplug finished it. 'nuf said!

Welcome to PB SAW. Beautiful place and wall. I think the guys above provided what you need.

Somehow you need to install deadmen back into the bank

Deadmen are not needed with this type of landscaping blocks. They are needed with most building blocks.

You don't have to use concrete for a footer.. A well dug out trench packed with 3/4- rock would work but you could put a couple in he layer of concrete (just dry bagged) on top of the rock then set your blocks an inch or so into the concrete, bury 3/4 of your first block it should be good to go..

Sounds like no matter what, he is going to need to lower or drain the pond for construction.

Thanks everyone for the good information. To answer a few questions. The truckload of stone that I put in the spillway I toted by hand in a wheelbarrow. It took most weekends for one spring and summer. All of my pond spillways & dams are inaccessible by any vehicle. I look on the positive side, it's good exercise. One very dry summer I rented a TerraMite, (small backhoe) and had some earth moving work done but as my property is wetlands, unless it's very dry, any heavy machinery just sinks into the mire.

As I mentioned in my first post, Big Pond has what appears to be the remnants of the original streambed flowing out of one side. I tamed that area a few years back and hemmed in the stream with these same wall blocks. And tho' that area becomes a torrent is rainy times, these wall blocks have held up and only tilted slightly. The spillway where I put the load of stone and eventually built my wall was caused by erosion. So, once the wall was completed and back filled with pond goo, it staunched the flow of water and the small side stream took over as the outlet. However, water being what it is, found a way to flow under my massive rock pile and under the right side of the wall. Still the wall held but strangely it was the left side, where there was no active flow of water, which began to tip forward.

I did cover the pond goo backfill with topsoil and planted grass seed and some ground hugging shrubbery. It did not grow so well as the area is very shaded. I had not considered the idea of building the earth up higher than the wall to encourage the rain water to flow over the top of the blocks as opposed to under. I will add that to my arsenal of knowledge.

Regarding how to proceed, I wondered if concrete was needed as a base. Unless we have a drought, it would be near impossible for me to dig a trench and lay concrete -- there is simply too much water. And I don't have any way to lower the level of Mystery Pond. So, the idea of putting in a layer of stone and then concrete bags on top of that as the foundation of the wall might be my best bet.

I must do something. My property is unique in that my house sits directly on the water, being only a few feet from the water's edge in some places. So my crumbling wall is very visible from my deck and it has become an eyesore. Yesterday Punxsutawney Phil declared it will be an early spring. So I, hopefully, will don my waders and begin my rebuilding in April.

Again, thanks for all the great info. I will be visiting this site frequently because I have a slew of other questions.

Is the pond with issues, stocked with fish? (Maybe I read that forgot now).. If so what are they and how long have they been there?

Gravel will work if the footing is solid but since this one is mud, the gravel will squeeze out and down. Eternity will be shortlived. Move the blocks before they topple(not that far down the road) because they are hard to pick up out ot muck. Then dig your footing. Make a barrier of plywood so that it taller then the water level. Try to make it as waterproof as possible. Then clean as much mud as you can from your trench. Then pour 8" of concrete and you will be good to go. Good luck.

If getting equipment back there is a problem, then getting cement back there probably will be a problem too. They make a post hole cement that you can pour out and the water will mix with it in the hole (no pre-mixing required). You might be able to use the same stuff for your cement footer. It IS more expensive than the normal cement, but maybe the "no mixing" part will offset the higher price.

Most rental places here rent a unit that has 1 yd of concrete in it that can be towed. Then ye ole wheel barrow does the rest. Hard work has made some men strong(I think it has killed a lot more).

Well if it was me, I would reconsider the design of the wall, if it is no longer having running water over it.

I would go with a more natural look and use as big of boulders you can handle...basketball size? Slope the bank enough so they do not topple in with time. Mix these with landscaping plants to help hold the dirt in. Still put a drain across the top ridge to prevent as much erosion down the slope as possible.

Carrying enough concrete in to make a footer just doesn't appeal to me. My back just couldn't do it. However as stated above, it is the best way (and just about the only way) to go for a true wall to stand the test of time. Side thought - instead of carrying all that concrete, I would be tempted to try engineering a big muck floating pad like an excavator would use to go across soft ground. It would have to be something like twice as wide as the height you need, then the wall fastened to it....

A yard of concrete can be done with 12 wheel barrow loaded half full.

So at the risk of asking a really dumb question here, since your house is so close to the water and you can see the wall right there from your deck, how do you get to your house? Do you also park far away or do you have some access point that allows you to get right up to your house? The point, probably obviously, is that if you can get a vehicle to the house, what prevents you from having easier access for moving the supplies? Sorry if I'm just missing something here, but I'm just not seeing it.

Aside, really neat looking piece of property. My oldest brother used to live up in the Poconos, in Tannersville, and I always enjoyed going up there to visit - just a beautiful area.

Good point cancel the rock unless you can get to some kind of solid ground.. Honestly i'd dig the the pond out and start over..

Hey, something else. Does this BOW ever freeze? And if so, could you bring the materials you need across the ice?