I’ve talked about these a couple of times, but didn’t have a picture of them or a sketch. I know it isn’t DIRECTLY related to homebuilding. But Since many of the folks here live in rural areas I thought some of you would be interested anyway.
Attached are some pictures of some “dry dams” on my parent’s farm. They were recently finished, so I got out to take a look at them yesterday.
A dry dam is designed to do several things. First would be to control erosion. The water backs up behind the dam temporarily after a heavy rain. The water is released slowly through a drain pipe. (The yellow thingy you see at the lowest point)
Since the water slows down, much of the sediment settles out rather than continuing on downstream. This helps keep rivers and streams cleaner.
Slowing the water down also helps reduce gullies in the fields. And releasing the water slowly helps reduce flooding downstream.
They claim that chemicals and nitrogen will also settle out to some degree. This will help with things like keeping atrazine out of drinking water, and reducing the “dead zone” in the Gulf of Mexico.
So all in all, I think they’re a great idea. The only downside I know about is that they’re expensive to put in. I think Dad spent $7,500 on 6 of these. But he’ll get some of that back from the ASCS through cost sharing.
Normal people believe that if it ain’t broke, don’t fix it.
Engineers believe that if it ain’t broke, it doesn’t have enough features yet.
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I thought these might make more sense if you could see a section view of a dam.
In this sketch, the field is to the right and the ditch is to the left.
First the trenching is done for the pipes. The (yellow) standpipe takes the water down to the drain pipe. (black)
Attached to the end of the drain pipe is one or more runs of field tile. That helps dry out the low area after the water level draws down.
Then the dam is built across the ditch to finish the job.
View Image
Thanks for sharing that. I just got back from making rounds on places I take care of in owners absence - we are in the middle of a monster rainstorm here right now. A town road ditch is full of leaves and ice, so the drainage is diverting acrosss the road and down his driveway, so I had to get out my shovel and dig/build a little bit of a wet damn before it got any worse. I just logged in to email him a report in case he has insurance to cover, which I doubt on this siort of thing.
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Very interesting.
Out here in the Chesapeake bay watershed, erosion control is a big deal. You won't get any building inspection if required sediment control measures are not in place, or clogged, or not working properly.
Agricultural activities seem to be exempt from that sort of thing, my guess it will only be a short time brfore all of Virginia farmland gets wrapped up behind one big stretch of filter fabric.
Edited 4/3/2005 1:44 pm ET by panama red
From what I've seen in my many travels in the area, Virginia's erosion and sediment control practices are most impressive, so far as construction and road work are concerned.
Has this helped keep Chesapeake Bay cleaner? Are the Chesapeake fisheries recovering, or is the Chesapeake waterman an endangered species?
Here in British Columbia, we generally let her rip, then scratch our heads on why the salmon are doing poorly...
yes, the local charter boat captains have had to pick up a second trade to fall back on, such as " construction"
In the big city those are called water retention ponds.
Used to capture excess run off form hard surfaces and slowly release it. use to control flash flooding and erosion control.
Now days even a developement of less than a dozen lots will have one.