Pond Boss Forums POND CONSTRUCTION Building a dam Straight dams vs. curved

The 6+ acre pond that I'm designing for my girlfriend has an 800 foot dam. It's roughly triangular and the 2 non-dam sides will be very irregular in shape.

The pond contractor marked the shoreline and the trees are in the process of being cut. I had previously told the pond guy that I didn't want a straight dam because I was going for a more natural look. He told me that the shape of the dam would be like a football. My concern is that the football shape he described seems to me like the standard shape you would get from a straight dam. We're going to maintain a road on top of the dam so if it's straight it will be very obvious.

As I've looked around I've seen mostly straight dams. If for some reason he bid on building a straight dam how much more will cost him to curve it at least slightly? He has to excavate clay for the core from an area 200 feet from where the dam starts and 1000 feet from the other end.

Also, does anyone have an "S" shaped dam. That would be my preference.

After the dam is finished can it be easily modified by placing topsoil on it, or does any additional material need to be compacted also?

A slight curve would add minimal length and difficulty. Think of a line cutting across the middle of a dinner plate. If the line cuts straight through the center, the semi-circular "dam" on the edge of the plate is much (1/2 pi or about 1.57) times as long as the straight line. If the straight line just slices off a little of the plate near the edge, the lins are much, much closer to the same length.

All things equal, making your dam 50% longer (if you went with a near semi-circle instead of a straight line) might add 50% to the cost. But all things aren't necessarily the same. Long, gradual curves shouldn't add much difficulty or cost other than for the slightly longer dam. But sharp, abrupt curves in the middle of a dam DO add difficulty and hence more extra cost than just the added length would.

My new pond has a 70 degree turn near one end (it was either that or build a much longer dam and lose half a small hayfield for minimal gain in pond area) which is very sharp compared to the gentle curve making up the rest of the dam. Working all the excavating equipment at this curve took longer (in the case of the sheep's foot roller my wife and I drove, notably longer) than on the straightest portions. And in excavating, time is money.

I would think a compound curve, such as an "s" with opposing curve directions, might have additional difficulties and additional expenses.

To summarize, a curved dam should fairly be more expensive than a straight dam by AT LEAST the additional length involved. Sharp and compound curves probably have legitimate extra expenses beyond what the increase in length involves.

P.S. Material added to the back side of the dam need not be compacted like the dam core. WRT material added to the INSIDE of the dam, if it were completely loose, I would be afraid it might slough off into the pond once wet. And any part of the dam, core or not, that you are going to make a driveway on should IMHO be compacted.

You can shape the dam anyway you want, it all depends on your budget. If the topography is such that it falls rapidly in the center of the dam sight and curving it is going to cost more dirt(money) vs straight it all depends on the amount of earth you are going to pay to get moved. In my opinion a Dam should be built based on the natural lay of the land you start with. The dam should be designed and located in the most cost effective spot to yeild the biggest pond you can get for your money. Straight or not it is all going to depend on your view point of the lake and dam. Example if your going to build your home at the tail of the lake looking across the longest point(highly recomended in most pond guides)you want really be able to see if it is straight or curved looking across the 6 acre body of water.(check out brettski layout prime example). It is your dollar do as you wish within your budget. Good luck and post pic's when you get going.

A dam that is straight at 800 feet long will, indeed, maintain the mundane appearance of just that. The dam we constructed last year is about 325 feet long and it is straight...but...one end wraps into a long arc and the other into a small arc. The inconsistent arcs combined with the shorter dam length allow it to blend somewhat. I am not disappointed with the final look whatsoever. Remember that the curb appeal you seek is gathered from the ground, not an aerial view. I think the long curve for a dam at 800 feet long is a good way to achieve the curb appeal. Another consideration is how the grade behind the dam will appear. If your slope behind the dam is somewhat steep, when you see that area, regardless of the shape, it will scream "dam zone". If you waste alot of the soil behind the dam to the extent that it gently stretches down and away to blend into the existing grade much further behind the dam, you will do much to make the dam appear as a natural geologic occurrence. Yep, alot of this has to do with $ and the existing grade that you are working with. In our case, we were lucky to be able to build the dam between two hills and get this look by moving only about 20k yards. quik pix
-
backside of dam examples at bottom of thread page

GW, I say your dam straight! (I can't believe no one saw that coming).


Wait, got another one....



Wait for it.....



Building suspense here....




Man am I on a roll today or what???


Ok, you can all return to your serious technical discussion. Theo made me hungry for pi.

Can I get back to you on that?

JHAP, I think no one saw YOU coming. Once again, you blindsided a serious discussion. Nyuk, nyuk, nyuk, nyuk.

15 yards for being offensive.

If I was building your 800 foot dam, I would build in some curves for free. It probably only takes 30-45 minutes more time, and would be a lot more fun than a straight dam.

I talked with the contractor today and he said we could work it out without a problem. I really don't need a radical curve. It is something that will be very apparent because the road into the pond site continues over the dam. He bid on building the dam a few feet wider to accommodate the road. That means when you get to the pond you'll be looking straight down the length of it.

Something like this?



I don't know the exact length but there is about 6.5 acres and 17 million gallons on the left side of it.

That looks great DP. I'd guess we're looking at about 200 feet there. Is that the entire dam?

OK. Dan, don't tell us yet.

I'm guessing the dam is 449' from end to end of what's shown of the dam in the picture.

Five bucks says I'm within 10' without going over.

No way.

Sunil, what are you calling the far end? I'm looking at a place in line with the photographer and the point where the middle curve of the dam meets the water.

In other words, a fairly symetrical number "3".

O.K., don't go away, I'll look it up.. I think I've got it in one of the pond files.

Yeah, that's the end of the dam, at the end of the "3."

449'

365 feet.

Sorry, no luck. I'll get it in the morning with the laser range finder.

Dang. I wanted that five bucks.

Dan, I believe you live at your pond, right?

It is only 10:30 PM.

I'm willing to stake the actual footage on your stride being counted as 3'.

It's going to take you about 150 steps to go from end to end.

The actual dam goes from where I'm standing to where the green strip on the far shore runs into the dam. The sewer cover is directly over the 8" tube thru the dam but has nothing to do with the tube. Don't know why it was ever put there but it's too heavy to move.

When I get time I'll post the story on how & when it was built and a few more pictures. Been told it was only a couple hundred dollars for fuel (1991 prices) and time spent between planting crops in the spring and harvest in the fall.

Dan

I hadn't even seen the sewer cover before.

I'm thinking that sewer cover needs to be about 4' in diameter to support my claim. Am I right, Dan?

A rock solid estimate of 449 to 459 feet from the man who can bench press, what is it now, Sunil, 700 lbs?

Definitely under 300.

Aww, I bet you can't bench press 500, GeeDub.

The last time I tried was in 1974 and I pressed 150 lbs. I weighed about 130 at the time though.