Pond Boss Forums POND CONSTRUCTION Soil questions Bedrock 6 feet down, now what? Help!

Hi everyone. All suggestions & opinions would be great.

I want to dig a 1 acre pond. We dug some test holes. Only got down 5-6 feet and hit solid ledge rock. On top of that we have a sandy loam soil (no clay). The site (grassy area)borders a swamp. The 2 lowest test holes have 1-2 feet of water in them (thats where the water table is).

Please flood me with options. My kids are patiently waiting!

Dynamite. 6' of water up there will not support fish thru the winter - it'll get too cold.

Agreed. Dynamite is your option. Just as 6' of water wouldn't support fish through the winter, a 6' pond would be dry here right now.

That was one of my thoughts. Cost of dynamite? Who to call? About depth, I was hoping for at least 12-15 feet. Large YP is my goal (and swimming of course, kids 5,7,9 years old).

There is a steep slope to the east of the site (where we plan on building the house overlooking the pond. The other thought was to dam the other 3 sides & line with clay or a liner (neither of which I have). Any thoughts? Thanks.

One option sell and purchase different property before building the house.

Second option; do a swimming pool instead.

Third option down size (?) the pond and manage it as a glorified wetlands. Winter aerate far end shallow, ice skate on end closest to house, and hope for minimal winter kills. YP do tolerate low DO and cold temps thus you may have success with them. Use SMB and a few WE as predators of YP.

Dig down to the rock and use the excavated material to build berms up around the hole to the depth you want. Since you have ground water that is so close to the surface use a pump to fill it and keep it full. You will need to line the berms with clay or a pond liner since your soil is sandy.

When you use berms take all precautions possible to prevent the berms from leaking. Most all berms, even clay berms, leak way too much.

Dig down to the rock and use the excavated material to build berms up around the hole to the depth you want. Since you have ground water that is so close to the surface use a pump to fill it and keep it full. You will need to line the berms with clay or a pond liner since your soil is sandy.

Thanks for the feedback guys.

Did some investigating & I have Whalan Silt Loam. Not that that really helps me.

As for digging it and useing the spoils for the berms. Thats what I was thinking, but even if I line the berms, won't the head pressure of the pond push the water down through the bottom if I don't line that too?

On another note, I have a spring about 700 feet away in the swamp that I could use to fill it if I ever figure out what to do.

I'm sure u guys have seen these beautiful blue ponds in quarrys before. I'm assuming that water is at the water table. So, is it possible that I blast down far enough to achieve that? And at what cost? I think ledge walls & outcroppings in the pond would be amazing!

I'll check back later today, gotta go. Thanks everyone.

I'm not good searching the forum, but I think I remember someone doing just what you're thinking. They made a pretty good sized hole in rock for a pond.

i cant believe what im reading here....dynamite is brought up as an option and no one is encouraging that? i would definitely look in to that just for the experience aspect....although i know nothing about dynamite..wouldnt the rock hes talking about hold water if it is solid? how much tnt would it take? he could just do part of the pond with it just to get some deeper holes

okay, let me ask you a few questions... what did you use to dig your test holes? i work in excavation and i can tell you that as a general rule of thumb when starting a project you want to bring out the biggest machine that you can get for your digging. the only reason i ask is because if you dug your test holes with an auger or a small backhoe you might...i emphasize might....be encountering rock that a larger machine might not have problems with.

while im not familiar with your local geology i can tell you that around here (northern california) i typically encounter lave cap and granite. lava cap is soft enough that a big excavator or a large bulldozer with rippers,say a d-9 or so can usually do a lot of damage without having to get out a breaker. on the other hand with granite, we always have to use a breaker. some of the blue granite that we have locally can test at upwards of 12,000 psi compressive strength, to put it in perspective, your average run of the mill 5 sac concrete for house slabs is probably about 2500 psi compresive strength. the point is though, bigger equipment may get the job done. you may want to re-consider the size of the equipment that you are planning to use.

also how deep do you want to go??? if your hitting rock at 6 feet and you only want to go to 10 feet, a big excavator with a breaker could get the job done in a reasonable time frame.

basically with rock, there are four possible solutions, only one of them is cheap:

1- dont dig

2- try to use a bigger equipment

3- a hydraulic breaker

4- blasting with dynamite, or use expansive grout or equivilant.

check with your local builing authority or local contractor on the use of explosives in your area. blasting can get expensive real fast. you have to core drill out holes for it, set the explosives and re-cover, usually around here we have to get engineers involved and it gets pricy real quick. your better option, is to use dexpan or something similar. if you have access to a large roto-hammer or a core drill you can buy dexpan with no liscence and it will break rocks to pieces overnight while you sleep. do a google search for dexpan non explosive demolition. this stuff works great, you might need a lot of it though.

good luck - justin

We used a big excavator. Not sure the model, but a huge Deere. As for the rock, it's solid limestone. We live on the Niagra Escarpement. It's this ridge that loops up and around all the way to Niagra Falls. You could be right about ripping the stone. I think it might depend on how fractured it is.

As for depth, the water table is about 1 foot above the stone. So if I do a "water table" pond, I'd have to go about 10 feet into the stone. Correct me if I'm wrong.

Thanks everyone.

Justin (jevans5050) brings up some great points. When we improved the road on our property we had a large granite boulder that went across the entire road bed. We had several contractors look at the rock and give us quotes for removing it. The explosive options (dynamite) were very, very expensive.

The company that we ended up hiring brought out a hydraulic hammer. I was amazed at how fast they were able to reduce the rock to rubble. They also mentioned that if the hydraulic hammer didn't work that they could use Dexpan but fortunately the hammer worked.

I'm not certain that I like the new, more serious JHAP. For you to totally ignore the possible responses to a dynamite-laden thread is really disconcerting. Are you fevered, my friend? Has the tax code changed radically and thrown you an unexpected loop? Is it just an inexplicable desire to increase your useful post count? Please, JHAP, come back to us!

What ever happened to Tom G? This is right up his alley.

I don't know what is happening, my theory is that one of my multiple personalities went on vacation without me. I'm really, really off my game lately. Suddenly some of my cranial voices have stopped speaking to me and one is now learning Tagalog which I find very annoying. It's hard enough to function with multiple personalities when you can understand what they are saying. And to make matters worse when I was working over the weekend I noticed a bunch of crows sitting on a fence that is outside my office window. They kept giving me the hairy eyeball and I'm quite sure that they are plotting against me. You can never trust crows, they are very devious.

Who are you? Oh, never mind.

Oh, I don't know. Based on this post, I suspect you may end up being just fine!

Well that's good news.


It still doesn't change my opinion of crows though.