Is it really so difficult to dig a large pond?

September 24, 2012 12:02 PM

Is it really so difficult to dig a large pond? I received a quote for the construction of a rather large pond, (80 x 45). And, the quote seems high. Tell me Me-Fites about your experiences constructing large ponds.

The idea is to have a large kidney-bean shaped pond towrd one corner of my property. Nothing regal, just a place for the dog to swim, cattails to grow, and perhaps a place to skate in the Winter.

I have plenty of space to spread out the removed soil, so hauling it away shouldn't be a concern. The quote included spraying weed killer over the affected area, brush-hogging before digging, final grading and planting grass seed once completed. Some of these are I'm sure optional. Total quote was a little over 6k.

So how hard could it be to rent some equipment, dig the hole, and spread the dirt around?

Have you done this? Perhaps you've seen it done.

posted by bricksNmortar to home & garden (15 answers total)

Yeah, it costs that much.

It's not the hole, it's knowing how to dig so that you don't have it cave in on you.

We had to dig up our sewer pipe and replace it. It was buried something like 10 feet down. This neccesitated a huge backhoe, and a twenty foot swatch cut through our newly landscaped yard (I'm still traumatized.)

IMHO, this is one to leave to the professionals.
posted by Ruthless Bunny at 12:07 PM on September 24, 2012 [1 favorite]

I have not done this, but FWIW, $6K sounds cheap for all that.

So how hard could it be to rent some equipment, dig the hole, and spread the dirt around?

Excavation equipment is very expensive to rent. You obviously haven't done this before. The learning curve will make this a losing proposition.
posted by jon1270 at 12:07 PM on September 24, 2012 [2 favorites]

Yeah, it costs that much. My son paid around that for a pond in upstate NY, and that was really just the digging, the landscaping he's done himself. This is not something you want to try to do yourself, you should not be operating that kind of machinery without training and supervision. While I was visiting my son this summer a neighbor died from overturning heavy machinery.
posted by mareli at 12:11 PM on September 24, 2012

I have a pond on my property which was dug by amateurs, and it's a nightmare. In the process of digging it they screwed up the drainage in the rest of the yard, so I've got a quarter-full pond right next to a swamp. As it turns out, a pond is a lot more complicated than a hole full of water.
posted by Nahum Tate at 12:18 PM on September 24, 2012 [6 favorites]

With a pond if they are most likely not just digging a hole, you have to allow for drainage of overflow, possibly lining it with some sort of clay if your soil is too free draining. Ponds cost that much.

As the old joke goes.

"A guy pushes his car into a mechanics and complains it won't start. The mechanic takes a spanner and adjusts one thing and the car starts perfectly.

"That'll be $100" says the mechanic.

"Your kidding me it only took you a second and all you did was make a quick adjustment."

"It's a buck for the adjustment and $99 for knowing what to adjust."
posted by wwax at 12:36 PM on September 24, 2012 [5 favorites]

Pond building is a thing. Do your homework, be careful and diligent, and you can do it.

Here's a book review from Kevin Kelley to get you started on your research.
posted by Slap*Happy at 12:38 PM on September 24, 2012 [1 favorite]

There are a million ways this can go wrong... but I still encourage you to consider doing this yourself. Not that it'll cost much less!

I just visited a (much-smaller) pond that I co-built years ago and it looks FANTASTIC today, and somehow, amazingly, it all still works. We had to think quite a bit about the shape of the land, and how water worked there, and where it drained, and what happened when the climate was wet and when it was dry, and where we could and should displace dirt, and we actually had to install an underground drainage system to assist in the plan.

BUT, if you do a bunch of reading and thinking and studying about what you're doing, you're halfway there. Then there's the other half—construction, digging, lining, etc.—which is easy to mess up too. But life's an adventure.
posted by RJ Reynolds at 12:46 PM on September 24, 2012

From the way you are asking the question, I suggest that the real cost of the pond that you are considering is mostly unknown, but considerably greater than $6K.

80x45, to a depth of 3 feet, "kidney shaped" could be as much as 250 cubic yards of soil. What is the threshold in your municipality for a grading permit? Are you on good terms with your neighbors? Will they rat you out? Finding out about your local grading ordinances after you have started is really, really expensive.

If you have a rainy season, some municipalities won't even issue a grading permit once it is likely that the job will be heavily rained on.

Have you done any kind of perc tests in the location where you want your pond? Some holes won't hold water, and might have to be lined with something to keep it there. Is seeping water from your pond going to induce a slope failure downhill somewhere, perhaps on someone else's property?

Where is your water table? Where is the nearest well?

Where is your bedrock? Are you going to be able to achieve your desired depth in the entire planned area of the pond?
posted by the Real Dan at 12:46 PM on September 24, 2012 [4 favorites]

Are you potentially able to sell the removed soil as fill? That might help offset the cost.

But yeah, as others have mentioned, several thousand for a pond sounds about right.
posted by saladin at 1:08 PM on September 24, 2012 [1 favorite]

Are the builders making a commitment to deliver the job as specified for $6K regardless of how long it takes (within the terms of the contract, naturally), or are they charging for time+materials and estimating a total of $6K. If it's the former, consider that they are also taking on most of the risk of the project and deserve to be compensated for that. All the issues the Real Dan mentions are things the builders could be on the hook to deal with. If your pond winds up damaging someone else's property, you'd naturally complain to the builders and expect them to pay compensation for their design/construction errors. A good chunk of the cost is going to compensate them for taking on both the delivery and liability risks inherent in this project.

You also didn't specify the depth of the pond, which obviously matters in figuring out the cost.
posted by zachlipton at 1:56 PM on September 24, 2012

You're definitely getting off cheap to have someone move all that dirt for you; are they a licensed contractor? Are they including permit fees? You may get away without a permit, but if you get caught (or eventually, when the house is to be sold) it will create a world of trouble. Permits are designed to make you think about all the things you clearly haven't thought of: storm water or groundwater pollution, retention and drainage, overflow, erosion mitigation, effects on neighbors, and so on. A house-sized volume of water is not a trivial thing to install on your property.
posted by Chris4d at 3:59 PM on September 24, 2012 [1 favorite]

It sound suspiciously cheap to me.

By the way, the 'soil' you will be removing is not the kind that will grow nice plants and grass over it. It will be mineral soil with no seeds or nutrition in it, and will take years of not decades to look normal. Your excavator guy will have to dig it out, put it in a truck, drive the truck and the excavator to the new spot, dump it out of the truck and then spread it around evenly. My (very cheap) guy is $1000/day for him and the excavator and the truck.

As others have said, if you haven't done a permeability test, you could end up with a hole, and not a pond. There are almost certainly permit issues, and if you are within striking distance of a watercourse (even a seasonal stream) it may be impossible to get a permit.
posted by unSane at 7:21 PM on September 24, 2012

So how hard could it be to rent some equipment, dig the hole, and spread the dirt around?


Renting -- easyish, but they may want you to have a qualified driver for the thing. You're going to need to rent an excavator, a tractor or bobcat with bush hog, and probably a dump truck too.

Digging the hole -- the easy part. But excavators are not simple things to operate. Worst case is it ends up upside down in the hole you just dug, with you inside. Things can go very wrong very fast with a big powerful machine like that. (Trust me on this).

Spreading the dirt around. How are you going to get it from A to B? A dump truck? Are you going to rent that too? What do you expect the dirt to be like? Once you're through the first 12" of topsoil, it's going to be sterile stuff that won't grow anything for a long time.

Grading is an art, and it will take you much MUCH longer than someone who's done it before.
posted by unSane at 7:26 PM on September 24, 2012

Ignoring permit questions (which are not trivial), I would be surprised if you could do this cheaper by renting equipment. At a minimum you'll need a backhoe or trackhoe for the digging and a truck with a dump-bed (or a large pickup and a dump-trailer) to move the dirt over the other side of you property (plus a way to spread the dirt). You mentioned brushhogging in the quote, so I'm going to assume there are vegetation removal issues, too, which either means more equipment or hiring laborers.

And then there are materials costs -- where I live, a pond needs to be lined with plastic or bentonite if you want to keep water in it, and you need to figure out overflow and drainage issues, too (and being next to the property boundary, those need to not impact the neighbor, obviously).

Four weekends of equipment rental at $1000/weekend puts you pretty close to your current quote, and I'd be surprised if a total novice could get things going that fast, and rental costs could easily be more. It would be a fun project to learn on, though, if you've ever wanted to run heavy equipment.
posted by Forktine at 5:44 AM on September 25, 2012 [1 favorite]

I built a much smaller kidney-shaped pond (some pictures, I'm in one of them for scale), and that seems like a good quote to me.

It was a nice spring project at that size. I faced some challenges and learned some things. But I can't imagine taking on building a much bigger pond without experience. Plus I didn't have to get weed killer, grass seed (quite expensive) or brush-hog (there used to be an above ground pool where I built the pond) which sounds terribly labor intensive. Plus what do you do with all the brush? I dug mine by hand so I didn't have to rent/learn large equipment but I am guessing they will let you make much bigger mistakes much more quickly.

Most likely, every few steps you're going to find out you need to rent/buy something else, thus eating into the small amount you might save doing it yourself.

We still have to landscape around it next year, so that's another cost to consider.
posted by mikepop at 7:06 AM on September 25, 2012