I am about to start a 5 acre lake, I met with the contractors and have inputs from the NRCS on the drop structure sizing. The pond location is a good one in terms of economics. It appears that it will only take about 10,000 yards of dirt for the embankment. The embankment is 600 ft long and will back water up for about 1000 ft. It has 6 foot of water at the dam without excavating and 3 ft at about 550 ft from the embankemment. The negative thing about this location is that it has a 400 acre water shed all cultivated soil. There is going to be much more siltation than is desirable. Any one have ideas on away to help control this? I am currently considering building a smaller dam up stream and force the water around it over a grassy area. The draw will be deepened in front of the smaller dam to catch silt which can be cleaned out ever so often. Any thoughts on this would be greatly appreciated.
Rocky -- Your thought is a great one -- trying to minimize the problem before it happens!! You can find a little information on the following website.
http://www.ngpc.state.ne.us/fishing/programs/aqhabitat/AQrestech.asp I know that it's not much, but maybe it will give you a start. Let's see if other people on the Forum post with good information. If not, I can give you the name and email address for the Nebraska state biologist who is in charge of their aquatic habitat work. He'll be able to tell you more about construction of sediment ponds.
I would say it depends on how much sediment you're getting. If you lime the sediment ponds & a hard rain covers the lime with sediment well ...
If you have access to the watershed maybe you could lime it?
Is there any way that the lay out would be conducive to a combination of terracing and Hickenbottom type risers?
http://www.hickenbottominc.com/docs/Hickenbottom_Inlet_Catalog.htm Here's the link. This would allow you to slow the movement of silt laden runoff through your watershed. In so doing, you would slow the water enough to encourage a lot of the sediment to drop out before reaching a well constructed silt dam.
I've actually not seen much discussion on this in the past on Pond Boss website. Maybe it's been on here and I just missed it.
Who was it saying cattails were good for catching silt? Was that Bob?
It could well have been.
IIRC, the thought was a cattail marsh/silt basin up stream from your fishpond.
I would say that cattail root structure would be nice for keeping soils intact, plus the plant itself would absorb nutrients such as phosphorous and nitrogen that are bound to the silt particles. That would work well in combination with my Hickenbottom theory, because the terraces could be constructed so that beds of cattails could be planted in them. If you are in a region that gets some smaller rains these would keep the ground moist enough to plant cattails within the terrace system. If not, then the terraces would need to be planted with hardier drought resistant plants.
Great idea, Bruce.
"Now, you too can make your rural pond look like the Columbus, Ohio freeway system!"
That's funny, Theo.
It seems like to me this would be the most economical method for SOME terrains to slow runoff for sediment dropout.
Rockytopper,
Holy smokes...400 Ac of drainage! I'm very curious to hear the results of the NRCS calc's regarding the watershed hydrology and potential storm inflow. It sounds like you're gonna have about 25 - 30 ac/ft of retention at normal pool after pushin' 10K yds for the dam. What sizes/volumes do they have planned for your principal and emergency spillway?
V interesting project for engineering...looking forward to followin this one.
I thought we might tempt Brettski to enter this thread.
He's the man when it comes to this sort of thing!
One of the ponds I used to work on had a series of long terraces which lost elevation in opposite directions as they progressed towards the pond. Each terrace end had a Hickenbottom at it's low end so the water "waggled" it's way to the ponds and had a lot of time to deposit silt. I'm kind of the "anti-expert" when it comes to this stuff. It's interesting to me, but I won't live long enough to ever really get it.
....and please don't ask me why I'm suddenly obsessed with Hickenbottoms. I think it's just because I enjoy saying "Hickenbottom".
(in your best Mr Rogers voice)..can you say Hickenbottom?
I like the way you say that!
Theo...ya got me
Currently I have a road along my shoreline that is built up to stop water from flowing into my lake. For now I'm trying to keep water out.
When I'm done digging and ready for water to fill it up, I'll put culverts throught the road with a deep collection trench before the culvert. This should catch some of the silt before it flows through the pipe.
Eddie
Rockytopper,
Are you saying the runoff from the watershed flows directly into the pond or does it flow into a stream that feeds the pond? If the former, would a levee system around the edge of the pond be of any help?
My first pond, which is supplied by an intermittent stream, has a small silt pond that, over the years, has collected alot of the fall leaf debris and silt from spring runoff. I don't know what effect it has had on the main pond though. I say this only because its location is about 15' from the inlet to the main pond. During heavy rains, the silt pond is probably just a small speed bump.
400 acres of watershed means that you'll have a lot of transient water in your pond. I have a similar problem, but with 165 acres of wateshed on a pond of only 3 1/2 acres. Sediment buildup can definitely be a problem, but fertilizing and fish loss can also be a concern. Regardless of what the experts say, you do have fish loss during heavy overflow events. I've found hundreds of fish in pasture areas behind my overflows.
I think Bob has the right idea. Terraces are the way to go, with the spillways staggered left/right from terrace to terrace. This forces the water to spend the most amount of time in the sedimentation pools and thereby gets the most sediment out. I used to work for a company which designed and built mining and soil cleaning process equipment. Often times we would have a slurry of water and soil which would need to be seperated and that is how you do it, except you would call them tanks and wiers instead of ponds and spillways. With 400 acres cultivated dumping into a pond that size, I'd say you'll have big time problems with chemical pollution, sedimentation and water clarity. I'd make as many catch ponds as possible and design them to be easy to clean out. Good luck.
Originally posted by TN Hillbilly:
I think Bob has the right idea. Terraces are the way to go, with the spillways staggered left/right from terrace to terrace. This forces the water to spend the most amount of time in the sedimentation pools and thereby gets the most sediment out. I used to work for a company which designed and built mining and soil cleaning process equipment. Often times we would have a slurry of water and soil which would need to be seperated and that is how you do it, except you would call them tanks and wiers instead of ponds and spillways. With 400 acres cultivated dumping into a pond that size, I'd say you'll have big time problems with chemical pollution, sedimentation and water clarity. I'd make as many catch ponds as possible and design them to be easy to clean out. Good luck.
Who's Bob?
Just once in my life I wanted to get some props on a pond design thread.
Now all my credit goes to "Bob". :p
:p
You know.....Bob Condomello
Never knew they were called Hickenbottoms...regardless, they work.
Land all around me has terraces leading into my property. All of them have those inlets and they manage to carry away huge amounts of water, while dropping massive quantities of silt behind the terraces...or so I've been told, because it's been so long since it ACTUALLY rained enough to run off, I can't remember.
Kidding, but in the 4 or 5 toad-choaking, stem winding, ground-pounding rains that I've witnessed here since '98, they've worked well.
Sorry Brice.
Would that be Brice Hickenbottom?
If I remember correctly, Rockytopper was the one who asked the question. He needs to jump in.
Bob
Bruce, Brice, Bob - This Condomello guy is turning into a reguar "Sybil."
To think he accused ME of having multiple personalities!
-Theo, et. al.
What ever happened to Meadowlark?
He's always into this diggin' stuff
Bob Hickendello, I heard he fixed potholes in the road with asphalt and dental floss.
TN Hill- Isn't there a formula for how much liquid, particle size and weight in a given size settling pond it will take to remove the solids. Something like that I remember from school.
:p
In smaller runs the terraces will be quite effective but on a huge flood there is nothing you can do.
Meadowlark is surely missed in this forum. As you can tell by my answer!
I'm guessing that Meadow is on a fishing trip. He mentioned something about a trip and then writing an article.
-Linus
Hey Linus....
I got a rock
Yes. Meadowlark and Debra are AWOL. I think ML went bonefishing and to some exotic place fishing to give his Georgia Giants time to grow. Deb was sick last time she posted. Help, Debra, this "humor" is killing me.
Burger...
Please hand me that "lamest post on the thread" award. Sorry.
C. Brown-ski
Brettski, don't beat yourself up, man. You can't hit a home run every time.
The 'X-ray of Matt Clark's back' comment was top notch.
Boy I steered the mud with this question. Fields are terraced and direct water into a water way. Grassed Water way has been neglected and now is a tree lined intermittent stream. I plan to create a silt pond above the main pond in the stream. The hickenbottom looks like the way to go to let the silt pond trickle in during the wet season and stream is flowing. I plan to make a natural spillway/terrace and force the flood waters around the silt dam over the terrace. The terrace will be about 100 ft wide 200 ft long and 2 ft tall. I'm thinking I should leave the silt dam open in the middle with out the hickenbottom or drain pipe and let the terrace get covered with a strong stand of grass then close the middle of the silt dam off and install the hickenbottom drain next year. Fescue is already very hardy in the bottom area. I understand it is very good for holding soil in flow areas. The aluminum drop structure has been sized with a 48 inch riser and 30 inch barrel. Emergency spillway is a min of 100 ft wide and currently has 4ft free board. These are preliminary and subject to change as the eng completes there analysis on the main dam. I may also get the NRCS input on the silt dam project.
Sense I started this post I have changed my pond location. The 36 acre property has to streams running thru and 2 pond sites, both would be 4+ surface acres. One stream flows from the south and one from the west on the north end of the property. The pond I described at first is the most econmic and will cover a little more surface area but will not all be inside the property line. The shallow end would be on the neighbors property. He is ok with it cause I'm funding the project. I have decided to build the primary pond on the north end for now. It will all be within the property lines. It will take about 16000 yds to fill the embankment. it has a 300 acre water shed. Here is link to a sketch of the pond sites. Note the little one in the drawing is the south side and is not drawn to it's current staked points. you can see the water line of both it's the 700 ft mark on the topo.
http://www.rockytoppers.com/realestate.htm. The photos are looking north at the pond location. Here is a link to terra server location
http://terraserver.microsoft.com/image.a...Lat=32.1987207. Lets start a little contest. Lets play "If this was your pond project" how would you lay out the fish structure jetteis etc...? If you have a scanner you can use the topo to draw up your idea and then post it. I will pick a winner or a combo of winners and go with that when the dozers and scrapper arrives. Thanks for the advice I will keep all informed as things unfold.
Well, that's one monster pond just NE. Probably a good thing it's there to assist regulating the watershed, but what's the prediction if it's full and it's emergency is flowing?...just curious. BTW, nice/generous principal spillway structure.
I can only offer one basic thought, and it pertains to your emergency spillway. You may (or may not) have seen a post I made regarding geotextile fabrics. There is a product noted within that post that could be a consideration to stabilize the vegetation at the emergency.
Geotextile Fabrics
The lake is down stream. it is a 35 acre flood control lake. The NRCS says that during a 100 year flood it could back water almost to my pond locations. The previous owner says he's only seen the lake go over it's emergency spillway once and the water didn't reach my property. There is also another large lake next to the 35 acre lake. They share the same spillway. It has a nice fishing log cabin on it's shores. Last year during a 7 inch rain that lake filled up and changed form a 15 acre lake to about a 100 acre lake and there was nothing but the top of that cabin sticking above the waterline.
I am no expert in design or pond construction, but I thought I would give some information on the lake design we have from a highly engineered lake that required state permit and wetlands mitigation. The lake design includes a continuos dirt berm around the lake that channels runoff to large "flats" in the lake proper. These have been designed with a gradual slope of from zero to 24" across a 1/2 acre flat. These areas contain aquatic wetlands plants that absorb excess nutrients as well as drop out silt. The aeas above and with-in the berms have been planted with bermuda grass to act to drop out silt as well. The idea is to allow siltation to take place outside of the lake, allowing for periodic rebuild of the berms with this silt. This also allows for water to migrate through the berms during light rain runoff through a terrace affect, to further clarify the water. Excess runoff flows across the mitigation areas, and wetland plants use nutrients and provide bait fish habitat.
Rockytopper,
All of the above mentioned ideas are great.
I thought I'd also throw my $.02 in here, too. I think the best idea for silt trapping in your case is a siltation pond (one that is upstream and designed to catch silt and be easily dredged.
If space is an issue, we also construct "sedimentation basins" that (through a lot of engineering) catch silt as head reduces and velocities slow to a point where they begin to fall out of solution and into this basin located at the bottom of the pond or lake.
Both of these methods allow for easy removal of silt when the time arrives.
