Building a pond?

[IndyIan]

Anyone have experience getting a small(1/5 acre, 20' deep) pond dug for them? Our 3 quotes results were; 2 at $7k and one at $20k!
The $20K guy will work on a material moved and time basis, so it may cost less, and he sounds the most knowledgable to me but the other guys didn't buy their excavators yesterday either...
I suspect the cheap guys have bid the job like things will go perfectly but will need more cash to continue if things get difficult, ie pumps required. The $20k guy has $2k for pump rental and fuel in his quote.
I think we have a fool proof location but I've read there's much more to pond building than digging a hole.
The soil is mostly clay glacial till but there's lots of gravel pockets around too.
Any success or horror stories?

 

[StevieC]

My folks have a pond that they put in at the house in the country where they are living now and it wasn't cheap but it's nowhere near the size of the one you want.

I think they spent $2K and it's 8' deep and 8 feet around.

Steve.

 

[mrsilv04]

My folks had a pond dug in '68.

They got lucky, as the state dug it for them just for the dirt, for a nearby road construction project. They had a low spot in the pasture, that wasn't good for much of anything else. It's a pond now.

Their pond is 2 acres, and is rectangular in shape. While it was being dug, they built a temporary dike down the center, for water control. They had to do a *lot* of water pumping. They'd pump one side, while digging on the other. Then, they'd switch sides.

But, they had to abandon it at a depth of 30 feet, as water control was becoming nearly impossible. They wanted to go at least 10 feet deeper. They cut into one water vein that was "bigger than a man's clenched fist", that flowed water all of the time.

Forty years later, there's plenty of bass, bluegill, and catfish to choose from. Several years ago, a family friend pulled out a 15 pound catfish out of there.

 

[Stu_Rock]

Like mrsilv04's story, you might be able to find someone to do it for free. There exist people called "dirt brokers" who connect people who need dirt with those who have extra.

For example, I have heard that people in my area are clamoring for fill dirt, so the removal cost here is $0 for the person with the dirt. The buyers will pay the brokerage fee and then remove it at their own cost. Of course the situation could be totally reversed if there's a dirt surplus in your region.

 

[crinkles]

20 feet is a very deep pond - 6m!

you mention gravel and till, which may mean the ground would be well drained. If the pond will intersect groundwater then your water level will stay much the same as the groundwater level. if groundwater is deep I doubt you'll have much water holding capacity in the pond due to the gravels and till. in that case you will need a clay or bentonite liner to seal the base of the pond.

it's all site specific so that's just my guess.

you're probably best off hiring them on hourly rates and flogging them to get the job done quick,.

FIL has had dams built on his farm by filling in valleys without preparatory works like keying in or stripping poor soil, most seem to do OK, there is only one in the top 3rd of a slope which holds no runoff as it is a bit more rocky and obviously the water finds a way through the shale. the dams are all right on the limit of what i call stable - at the point of falling over.

why don't you get an geo-engineer to come look at the site and talk you through it all he may be able to give some good advice, his cost may end up saving you much more than his fees.

 

[Cup of Joe]

Get on TractorByNet allot of guys have built ponds of all shapes and sizes. Eddie Walker has built a lake and is a general contractor so pay attention to his posts.

Here is a recent pond thread.

http://www.tractorbynet.com/forums/projects/179700-cost-build-1-acre-pond.html

 

[tom slick]

Any time there is more than 10% difference in contractors' bids you need to evaluate their scope of work carefully. Your 7k bid a different amount of work than the 20k bid.

What are you doing with the dirt that is dug up? If my numbers are correct, 1/5 of an acre 20' deep is 6500 yards of dirt to export. That's 4300 tons, which is 70+ transfer dump loads at $80/hr is $6k in dump truck services alone, then you have to pay someone to receive the dirt on top of that.

Don't forget to think about aeration systems and fish to keep the pond clean.

 

[IndyIan]

Thanks for the replies.
No free 30' deep pond for us(that would be amazing!), gravel and clay and everything in between is common here, and dump truck access isn't really practical.

Due to the internal slope and the pond design, the hole is going to be around 3400 yards and the dirt will stay nearby. The cheap guys plan on pushing the fill away with a dozer as the digging is done. The expensive guy says that won't work as he's pretty sure it will be almost solid saturated clay which will turn into a slurry unworkable mess by a dozer going over it dozens of times, so everything has to be moved by the excavator which means the clay out of the middle will be chucked around maybe 5 times!
So moving the 3400 yards by excavator several times is where he gets his big quote from.
Also the 20k man talked about the issues Crinkles mentioned and the cheap guys did not, I think they are basically going to dig the hole and hope it stays filled with water!
We are going to see some of the 20k guys work tomorrow so hopefully that will make the decision easier.
Basically all we want is to have it suitable for trout and swimming off a dock, and be able to plow good size ice surface on it and we'll see if he can do that for less than our original plan.

 

[crinkles]

you could reduce some of the uncertainty by digging 2 or 3 trial pits across the footprint of the dam. maybe 5m in length and 0.5m wide.

If it were my place i'd dig them to the depth a typical excavator machine can. A JCB 3CX can go 5m with an extendahoe and go for about $80/hr australian down here.

I'd leave them open for a few months to see how water behaves in them.

If you are going to rely on groundwater to keep the level up then this will give you a good indication of what it would do. If you'll be relying on runoff, maybe not so much, but you can try emptying a water truck into them and see if the water level drops and by how much over X number of days.

trail pits can be dangerous though (people can fall in, the walls can collapse, etc) AND NO ONE SHOULD CLIMB INTO THEM UNLESS MADE SAFE BY BENCHING OR SHORING so i'd recommend fencing them off until you can backfill them.

you will still have the risk of ground conditions changing form the trial pits moving away from them, and you may not pick up any macro effects on how the ground behaves there.

you'd probably only need a bakchoe for 2 or 3 hours to do these pits so should be less than $500.

if the trail pits perform well then you'd have a better idea of what the whole earthworks job will do, without having to incur the larger costs to find out.

this is general advice and I accept no liability for anything I said.

 

[crinkles]

Originally Posted By: tom slick
Any time there is more than 10% difference in contractors' bids you need to evaluate their scope of work carefully. Your 7k bid a different amount of work than the 20k bid.



amen. I wish my clients would realise this.

 

[IndyIan]

Originally Posted By: crinkles
you could reduce some of the uncertainty by digging 2 or 3 trial pits across the footprint of the dam. maybe 5m in length and 0.5m wide.

If it were my place i'd dig them to the depth a typical excavator machine can. A JCB 3CX can go 5m with an extendahoe and go for about $80/hr australian down here.

I'd leave them open for a few months to see how water behaves in them.

If you are going to rely on groundwater to keep the level up then this will give you a good indication of what it would do. If you'll be relying on runoff, maybe not so much, but you can try emptying a water truck into them and see if the water level drops and by how much over X number of days.

trail pits can be dangerous though (people can fall in, the walls can collapse, etc) AND NO ONE SHOULD CLIMB INTO THEM UNLESS MADE SAFE BY BENCHING OR SHORING so i'd recommend fencing them off until you can backfill them.

you will still have the risk of ground conditions changing form the trial pits moving away from them, and you may not pick up any macro effects on how the ground behaves there.

you'd probably only need a bakchoe for 2 or 3 hours to do these pits so should be less than $500.

if the trail pits perform well then you'd have a better idea of what the whole earthworks job will do, without having to incur the larger costs to find out.

this is general advice and I accept no liability for anything I said.

I dug a hole by hand down a metre a few summers ago when it was really dry and it filled up then and has stayed that way, not that means a whole lot but its a good sign anyways that the water table is usually right at the surface.
There's about 50 acres that would have surface run off to the site, but its this water after it gets into the ground that we want to use.
We did a tour with the expensive guy to 6 sites he's done ponds on near us today. Many people had him back to do another pond as well so they were happy with his original work. We decided to go with him but with a redesigned pond thats the same size as our original plan but much cheaper to build. He had built some very very nice ponds for quite a bit less than our first quote.

 

[crinkles]

I hope you get good service from him and it all works out! enjoy!

 

[MNgopher]

Make sure you or your contractor pulls a grading permit, if one is required. One of the "fun" things I get to deal with in my day to day job. We issue permits becuase:
A.) the state mandates we do as part of a permit we hold from the state.
B.) To keep people out of civil court (I didn't know it would flood my neighbor out)
C.) to keep people out of criminal court for disturbing a wetland. (The state has wetland preservation laws above and beyond the federal requirements).

The side slopes for the depth you are going to are steep - we allow 3H:1V slopes max, 4:1 preferred, you may be close to or steeper than that. Also make sure you have enough water (groundwater or surface) to keep it filled.

Good luck!

 

[IndyIan]

We seem to permit/regulation free as there is no surface water at the site currently, its just very saturated soil. Funny thing is once with get the pond dug, technically we'd need permits to modify it. Hopefully we won't have to work on it after. No worries about flooding anyone in a catastrophic failure either, it would raise the 10 acre wetland down stream a couple inches for a day I'd guess.

As for the slopes, most of the ponds we saw today would be 2:1, some steeper even. The glacial till here seems to hold a steep slope once there is water in the hole and a bit of vegetation established.

 

[crinkles]

take some photos of the area you want to put the pond in.
I agree 3H:1V is probably best

 

[IndyIan]

Here are a couple site pictures, the cat tails indicate it always stays wet.
The cut area shows about where we want the water to be. I can't really get a good picture of the elevations on the site as their are trees blocking all views from any distance or height.

Here's a 3D view I made of our property a while ago. I added the pond location. I guess looking at it now there seems to be alot more land area uphill than I thought.

Here's a simple map so you can see the contours (5 metre interval), the yellow outlined areas are designated wetlands although one polygon definitely isn't wet. Actually its amazing how wrong the topographic data is just on our property.