pond overflow/spillway ideas

[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.