pond overflow/spillway ideas

[LD1]

Looking for some suggestions as to what others have or have seen. Most all ponds I have seen in my area don't really have an overflow so to speak, but also don't have a lot of fill water coming in either.

Currently, my pond has a 12",culvert with 2 8" culverts for an overflow. I did this cause I need more than a 12, but didn't want to go bigger cause I didn't want to have to build up and over that much higher. The pond is fed with 2 12" culverts and a few 4" tile. The 12's flow full with a good rain. But I am wanting to redo the spillway and get rid of the "hump" over the culverts. So looking for ideas. I also want to be able to drive over it.

Considering the following.

1. Concrete swale. Kinda a shallow u shape. About 4-5' wide and 25' long. But worried about freezing, and not having a great base. My soil all around the pond is thick black waxey muck, that sticks to everything, and never really drys.

2. Considering stone. Not sure what size to get to not wash away. And am afraid it wouldn't support driving over very well due to the muck. And to be thick enough to be firm to drive over, would mean digging deep enough that water would flow through the rocks an cause a lower pond level.

3. Just leave the culverts and live with it.

I appreciate any suggestions. I'll see if I can find a picture of what I am dealing with.

 

[LD1]

 

[TomSeller]

Sure looks good to me. Nice work. WOW ! I would tend to a concrete swale overflow but my ponds are more ground water than flow through.

 

[LD1]

This is definataly a flow through. You can see in the second pic. That was last spring.(the first spring after it was dug). The first pic is how it looks now. But I don't like the hump.

I have read some places online that concrete isn't good for a spillway. Ice and frost heaving, which is a definite concern heren and also erosion and washing out underneath, since I cant really do a suitable gravel base as that would undermine the spillway.

But have also seen several nice looking concrete spillways online too.

I am not opposed to gravel. But what size? I got a load of #57's coming for driveway maintenance. But am afraid its too small and will wash away.

I want whatever is going to last the longest and still be able to drive over with the tractor and mower.

And if I go with rock/stone, is limestone or gravel better?

 

[dave1949]

http://www.factorydirectlandscape.c...category_id=15&option=com_virtuemart&Itemid=2

I would check out geotextiles, filter fabrics. They should keep the muck out of the stone if you build a rocked spillway. I would use 6" to 8" rock, river rock would be nicer looking than crushed limestone. I wouldn't use much gravel if you have a 12" culvert running full, that's a lot of water and maybe enough to move gravel.

You could call a vendor, like above and describe the situation, email a pic whatever, and see what they recommend. Rocked spillways would be my choice over culverts or concrete.

 

[Gary Fowler]

Why not use the same rock that you have around the perimeter? It looks large enough to hold without washing away. You could put down some geotextile fabric first then a couple layers of rock should hold. Use a broken rock with irregular shapes so it locks together rather than round or smooth shapes.

 

[Gary Fowler]

Also you could raise the spill way up so the pond could hold more water. Of course this would need to be done when the pond was a bit low so you wouldn't have to content with any overflow. Remove the culverts and backfill with good clay soil, then rock over the backfill to the elevation that you want to hold water. You could make the water level be almost to the top of your levees. Just make sure the spill way is wide enough to handle ALL the overflow without any going over your unprotected levees.

 

[Gary Fowler]

Here in Arkansas, the AG Extension service recommends (requires it if they participate) a spillway be located on the upper end of the pond. The overflow travels around the levee base by virtue of a swale and is directed to a drainage area, be it creek or canal. They don't allow culverts at all as they say they are impossible to size correctly due to differing amounts of runoff. With the spillway located at the upper (shallow end) and 20 feet wide or so, it will not allow the pond to over flow its levees. I don't know if your pond could accommodate something like that or not.

 

[Western]

My grandfather had a constant pass through pond when I was a kid, it has a concrete spillway with a foot bridge over it and has been solid for 50 years. This is outside Harrison Ark, and plenty of freeze/thaw going on as well. I do believe they poured flat walls into the ground front and back, like a dirt stop/footer. This pond was 5 acres

EDIT: He had a wire mesh wheel that turned with the flow to aid in keeping stoked trout in, actually worked. It was strong enough to drive a small tractor over to mow the bank, he just had some iirc long RR type ties acroos beside the spillway.

 

[oosik]

The outlet to my 5 acre lake is thru a naturally restricted area. It ends up being about 20 feet wide and I've filled the restriction with stone - 6" to 8" and some gravel. There is never a heavy flow so washout is never a problem. The water brings debris to the outlet and it deposits between the stone and further restricts the outlet flow. I more or less control the lake level by the amount of stone and gravel that I place in the outlet. If too much water - from local rain or snow melt - ever raised the lake level it would simply flow over and thru the stone I've placed in the outlet. Thru an entire season the water level will fluctuate about 14 inches. The lake is 80 feet deep and is fed from several springs.

I have never considered creating a bridge like structure at the outlet because there is a 150 yard "moat" between the little 5 acre lake and the big 120 acre lake that the little one flows in to. In the spring, when water in the moat can be up to three feet deep, I only cross it with the ATV. A heavy vehicle, such as my tractor, would most likely sink to unheard of depths.

 

[Citydude]

If one of your criteria is to be able to drive on the overflow, concrete would be the best. I contract mow the city's containment ponds. They used 8"+ sized rip rap for the overflows. It looks nice, serves the purpose however is a weed magnet. Its a pain to weed eat....

 

[RDrancher]

I'm watching this thread with great interest. I have a small (130'x80') pond job coming up soon that will be located where two good sized natural swales intersect. My plan for an overflow is an 18" corrugated steel pipe combined with stone (rip rap) above it just in case the pipe can't handle the flow. I'll drape geotextile over the top of the dam to extend below the pipe quite a ways on both ends. I'll create a wide depression above the pipe and cover all of the geo with rip rap.

Also, when I dig the pond the entrance will be excavated quite a bit deeper as a silt retention basin.

 

[SPIKER]

LD1: Pond is looking great!

What I would look at doing is using some concrete (shaped like a parking lot wheel stop) in sections & placed w the Kub. off to the left (first pic) you have a round hydrant/burn ? pit. about half way in between there and the culverts is where I would place them.

Side by side on good sized rock, would have to dig down (back 8 or 10 feet from the pond edge) to get them all in there. Lay them in a corduroy road fashion in a two by two (right side up then upside down) an inch or two apart. Here is a link to google for corduroy road https://www.google.com/search?q=cor...Blue%2FviewImageData.jsp%3Fid%3D80322;512;412

With the Kub get the spillway out & around the back side of the lip (leave covered) that is between the culverts and that spigot/pit. Then once you have that done use the kub to cut in the rest of the spillway up to the pond & fill it with some larger decorative stone like the shoreline has. Might even be able to raise the level some to make the bump of the culverts less obvious, use some 90 or 45 degree fittings on the culverts to get them under water level some...

You might even be able to sued round fence posts for the corduroy road out of treated lumber & could hold up well enough as MOST of the water would still be thru the culverts & spillway only heavy rain flood use.

Mark

 

[LD1]

To answer some questions, mainly to Gary fowler:

I have considered using stone like I have around the perimeter, but that was alotnofnwork loading and unloading all by hand from farm rock piles. All of which I am farmed out of now and cannot get to.

I cannot raise the water level. One of the culverts feeding the pond come under the roan. Raising the level at all will allow water to stand in the culvert and/or flood Tue field over there.

Cannot to an outlet at the upper end either. and there really isn't a levee or dam either. This was all flat ground with just a shallow swale running through. So no dam was constructed. Just a hole dug, overflowing into the existing swale at about the same level.

 

[dodge man]

You may have a local soil conservation office that can look at it and give you some free advice. I agree with using stone about like what you have around the edges. It could be a little smaller. Around here it is called rip rap and putting a fabric under it would help a lot. One thing to keep in mind with culvert sizes. 2 12" pipes don't equal a 24" pipe. Two 12" pipes would actually flow about half what a 24" pipe would. The reason I bring this up is I bet the two 8" pipes you have don't equal the capacity of the 12" you have but I'm not sure without crunching the numbers.

 

[LD1]

Out here in the sticks, not much in the way of local offices to offer advise.

As to the culverts, I have 2 12" feeding the pond. That's an inside area of 113 sq in each. So I need at least 226 on the exit not counting surface runoff, or the 4" tile. With 2 8" plus 1 12" for the exit, that gives me 213 sq in. Its a tad undersized but the 1 12" feeding don't flow full bore. Hasn't been an issue in the two wet springs I have had so far. A single 18" would only flow a tad more if than my arrangement now if flowing full. But to flow full would also mean water levels would be 6" higher.

But as side from all of that, I want to get rid of the hump and rather have a swalw with rip rap. I can't get ahold of my stone guy, but was told by some others that rip rap is lots more $$$ per ton. Cause its so large. I wonder how well #1's or #2's would hold?

Where do you get this "fabric" that everyone mentions.?

 

[dodge man]

Its often called a geo-fabric. It looks like the fabric that you put under landscaped areas to keep weeds from growing through it. I suspect the geo-fabric might be a little heavier though.

Where do you get it? I'm not sure. I work for an civil engineering company and I've seen a lot of it installed but don't know where it comes from.

 

[bcp]

Culvert capacity:



Bruce

 

[DB Pilot]

Well, LD1 I had a pond built last year. It is 6' deep 130'x90' teardrop shape. The 12" overflow pipe is down the 6' and underground out to a natural creek. The Spillway is to one side and 8" below the top of the overflow tube. The excavation guy only asked us were we wanted to overflow tube and how big a pond then went to work. He did show us examples of his work in the area so we knew that the pond would hold up over the years.

That's about all I know about ponds. My real reason for this reply is that I like your dock. How did you support the water side of it and how big did you build it. Looks real nice. :thumbsup:

 

[dave1949]

For the fabric, I would check with area landscape/hardscape outfits, masonry supply stores, excavation contractors, outfits that do road work for the state or county, the lumber yard may be able to order it for you.

A whole roll of the good stuff is relatively expensive and way more than you need. If you can find a contractor who has some on hand and would sell you some, that would be ideal.