Pond Boss Forums POND CONSTRUCTION Building a dam Why make the front of the dam so dam steep?

Is it simply to avoid the cost of moving too much dirt?

Or is it that the material usually isn't available from the pondsite regardless of the cost to move it?

Or is it that most people don't want to give up the water that would be displaced by forming a more gradual slope?

I believe that in at least some cases people have to find places to spread out excess material from pond construction. Could that dirt be used to build up the bank?

HI GW,
I think it is because one person tried this, the next person saw it and said thats the way to do it, because thats the way they did it, and it eventually trickled down to you for asking the question.

Excess dirt could be used for most anything you could come up with. Ya could even sell the stuff.

GW,

With dozer construction, it's really quick to push the dirt up into a pile as opposed to transporting it. It's quicker to push it up steeply than to work at making a broad, gradually-sloping dam. A steep pile is more likely to collapse when the pond is filled, so I don't see why anyone would make a dam less than 3:1 slope.

I can see why builders would want to build a dam a foot or 2 higher than necessary. That's an excellent way to get extra soil compaction, and a good solid dam.

OOPS, Still learning this. - A steep pile is more likely to collapse when the pond is filled, so I don't see why anyone would make a dam less than 3:1 slope.

Good point! I think that solves the problem.

If the material is available I'm going to request a 4:1 slope on our dams. I believe our contractor is planning a 2:1 for the front of Cindy's dam and 3:1 for the back. There may be a shortage of dirt in her case because the dam for her 6+ acre pond will be 800 feet long.

A lot of dams are steep because a steeper higher dam has the same amount of dirt as a lower flatter dam, so roughly the same cost.
The higher the dam the bigger the pond so some people go for the steeper higher dam.
You are right to request a 4:1 slope if it can be done IMHO.

Thanks for the feedback Kent. Hopefully I can work something out with our pond builder.

GW, mine is a 1 to 1, so it is steep. That said, it is thicker than recommended on the top.

Follow the money. My earthmover told me that he could haul for another week on the back side, to make it 3 to 1. My engineer guy thought we were fine as it. 5 days at $2000 a day, or leave as is. I left it as it. I can drive a 4' x 4' tractor up the backside, but my balls are in the back of my throat.

The pond contractor stopped by last week to see how the logging was going. He said that if there's enough dirt available he'll do a 4:1 on the front of the dam. I think the back side will be 2:1

I wouldn't go steeper than 3:1 anywhere simply because any steeper is very difficult to mow and walk on. Underwater areas steeper than 3:1 are very difficult to climb out of if you're swimming or would happen to fall in.

I would do just the opposite. 4:1 on the back would make mowing alot more enjoyable. 2:1 on the inside will help keep the cattails down. Another option is to have him make the front 4:1 to the water line then steepen it to 2:1 below the water line.

I can see the logic in that JBL, but the dam will be the longest side of this pond and I'm not partial to walking/fishing such a steep bank. Now that I think about it I may be wrong about the intended slope of the back side. The dam will be about 14 feet tall and we've cleared 80 feet behind the center part of it.

A consulting forester that I've been working with has a simple solution to his steep dam, he burns it. It should be relatively easy to control a fire that's between the top of a dam and the pond. I believe that grasses come back pretty quickly after a burn because of the nutrients that are made available by the process.

I've also wondered about letting the back of the dam go wild instead of mowing it. I understand that it's risky to allow large trees to grow there, but annual cutting of saplings might be simpler than mowing.

What about planting species of small trees on the dam? We have wild Azaleas growing on every part of our property and I've never seen one over 15 feet tall. Maybe there are some other trees that get a little larger but take several decades to do so. I'm thinking that you might be able to create a canopy that would limit undergrowth (therefore mowing), but that wouldn't put the dam at risk, at least not for 20 or 30 years. I know it's a bad example, but our pond contractor planted trees on his dam that grow large. When I asked him about it he just said that if a tree dies and compromises the dam he'll just fix it. Normally we get 50 inches of rain per year so it's not usually a big deal to lower your pond for repairs. Of course I understand that dam repairs won't cost him anything. Still, if the dam needed repairs 20 years from now I think I could live with it.

Well the site is cleared so I'll have to decide soon!

GW, I have a couple of strips I let "go wild" and do clearing work on once a year. There's a 15 foot wide strip next to the subdivision next door with trees planted on it (hurry up and grow thick enough to stop lawnmower noise, please!) that I remove briars (mostly multiflora rose) from every Spring, and the lower 2/3 of the pond side of the dam where I cut back the small willows that pop up every year. The first is too tree-crowded to mow and the second is too steep to run a tractor on. I would LOTS rather be able to mow each of them several times a year instead of spending a half day each on with a brush axe or the weed wacker.

What about the low canopy idea?

Tree roots of any size worry me.

It's not just the cost of fixing it someday, but the cost (and liability, depending on what is below the dam) of a catastrophic failure which could occur if you have a small root problem become a dam breach in a hurry.

You've got 80 feet cleared for a 14 foot high dam, that's also a place close to the pond where it's cheap to dump dirt from the basin. I'd make both sides of the dam easy to mow if it was me. I spread a lot more dirt behind dam #2 than I did on #1 and it's gonna be noticeably nicer to mow on the new dam. I'm glad.

Dear GW:
The answer to your first question is "yes" the price is almost always the reason not to move too much dirt. Also the back side of the dam is as important as the front. Dirt placed on a 3:1 slope helps the dirt to not slip. A steep front slope has more erosion from wave action and is harder to maintain and repair. Calculate the difference between a 3:1 slope and a 4:1 slope and you will surprised at the difference in the amount of dirt.

We elected to remove a whole buncha dirt from the pond side and fill in the valley behind the dam. The guesstimate is around 20K yards total with the dam. It is a very nice gradual slope that we planted with grasses and flowers. The top 2/3 of the slope is warm season grasses with wildflowers. The bottom 1/3 is cool season grasses with red and yellow clover. Our rainfall was lousy right after we planted, but the flowers still managed to come in pretty well. The grasses are much slower to come in. We planted at the end of May; the pics are mid August.
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...standing at the dividing line between the cools and warms, looking to the top of the dam
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...looking back down
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Cost aside, there might not be enough dirt to make a 4:1 on both sides of the dam. I may have to settle for 4:1 on one side and 3:1 on the other. Question to you pond builders is; which to make steeper, front or back?

1 vote for:

Make the water side steeper and the grass side less steep.

...make that 2 votes

GW
4:1 on the front and 3:1 on the back.

Maybe it could be terraced.

I was leaning towards making the backside steeper....

I just re-read my last post and I got it backwards. I've been thinking that I would like the front of the dam more gradual because I'm more concerned with the appearance of, and ease of walking on the water side.

What are the advantages of a steeper front for you all that prefer it?