Pond overbanking ideas !!!

[dave1949]

Here is the pic,,, The big rocks I put in there when we were trying to haul wood out just as the snow was melting,, They wil be coming out as soon as it dries a bit more,,

Are you planning on just having a spillway/overflow that you can drive over and no pipe? My pipe is just a PITA, I am thinking of having just a rocked spillway for overflow. I really don't know what the pipe is supposed to accomplish. I wondered if ice would build up in the spillway in winter and cause late-winter of spring rain water to go around it?

20_20 Is there a web site that has a pic or diagram of the the log arrangement? I understand you to say there would be two parallel logs going down the pond bank ? Is that to prevent erosion of the bank where the water enters the spillway?
Dave.

 

[hr3]

Dave ,, Yes I would like to have just a spillway like you say,, but am too conserned with it freezing up and just overbanking somwhere else,,, I don't want pipe drain.. and don't have the down drop for the ^ shaped thing.. although nice idea,,

I just need to figure out how to install the spillway so it does it's job,,

 

[Coyote machine]

I have about an acre or more pond about 10' deep at the middle. It used to have a culvert of black 18" or so pipe that was supposed to keep the constantly spring fed pond from blowing out the embankment on the far side of the pond. Over time the corrugated pipe allowed water to creep under its corrugation and it eroded the bank. I had it taken out and the excavator took 6-10" stone and dumped some in the pond side of the spillway and then some at the place where I wanted overflow height to be set. Then he put rip-rap stone on the downside and away we go. It has been about ten years since that was done, and summer before last we had a ginormous rainstorm and it washed out the spillway. The only thing that saved it from washing it out completely to the pond's bottom was the stone on the inside of the pond embankment. The water was so bad it tore out the 2" town metal culvert where the pond's water runs under the road!

Since then I have added some more stone and brought some back from where it washed over the top of the spillway.
I'd say unless you are absolutely set on having a pipe don't. Just go with stone like a waterfall, making sure to put plenty on the inside of the pond's bank to keep rushing water from blowing out the bank and spillway when torrential rain occurs. Note: I've experienced absolutely NO maintenance or ice problems, ( except as noted above), and you can drive a Jeep on my pond most winters at some point.

 

[dave1949]

I have about an acre or more pond about 10' deep at the middle. It used to have a culvert of black 18" or so pipe that was supposed to keep the constantly spring fed pond from blowing out the embankment on the far side of the pond. Over time the corrugated pipe allowed water to creep under its corrugation and it eroded the bank. I had it taken out and the excavator took 6-10" stone and dumped some in the pond side of the spillway and then some at the place where I wanted overflow height to be set. Then he put rip-rap stone on the downside and away we go. It has been about ten years since that was done, and summer before last we had a ginormous rainstorm and it washed out the spillway. The only thing that saved it from washing it out completely to the pond's bottom was the stone on the inside of the pond embankment. The water was so bad it tore out the 2" town metal culvert where the pond's water runs under the road!

Since then I have added some more stone and brought some back from where it washed over the top of the spillway.
I'd say unless you are absolutely set on having a pipe don't. Just go with stone like a waterfall, making sure to put plenty on the inside of the pond's bank to keep rushing water from blowing out the bank and spillway when torrential rain occurs. Note: I've experienced absolutely NO maintenance or ice problems, ( except as noted above), and you can drive a Jeep on my pond most winters at some point.

Thanks for sharing your experience. Good to know the spillway is not affected by ice accumulation. Sorry about the rain washout. Hope the town didn't complain My pond outflow runs into what is already a wooded wetland type of thing. Hardly any standing water but plenty of marshy spots. It does a pretty good job of absorbing my disasters.

I have a good supply of large (1 to 2-1/2 feet) rocks, just have to mine the old stone walls that seem to be everywhere on my lot. I was thinking of constructing a spillway by starting with small stuff to cover the soil, then adding larger rocks on top to hold the small rocks in place and buffer the water flow. I was thinking of a width of about 12'. Does that make sense?

Do you think the slope on the spillway was too fast and that helped the washout, or just the volume/speed of water started cutting into the bank and enlarging the spillway? Where my spillway would leave the pond, I have about 40' of level ground to work with, then I would need to deal with a bit more slope but nothing drastic.

I can see the pipe just isn't going to cut it. High maintenance and would be pretty expensive to build it tough enough to withstand ice lifting and frost heaves.
Dave.

 

[Coyote machine]

dave1949,
Thanks, I'm always glad to share what I've learned. Hate to see constant reinvention of working wheels
Fortunately I was out of state when the culvert at the road that gets its water from my pond and land washed out. The town road guys gave me some flack for sure; and they told me it cost $2000 to fix! Ah, something for my taxes finally!
I have an area where the water exits the spillway that is about 15' wide that is the barrier or dam that keeps the water in the pond. We dug out to where the highest water level would be as the water comes out of the pond and across the dam. The spillway is about 20' across at its widest point from side to side. This direction is perpendicular to the spillway. (The 'mouth' of the spillway, for descriptive purposes). Then the run from high water across the spillway from pond side to exit on the downside is about 12-15' (aprox).
The most important thing IMHO, is to add enough rock to stop the hydraulic pressure and possible leaks on the pond water side of the dam, and the spillway will take care of itself if the water can flow over it without too much resistance - hence the 12-15' for the water to flow almost horizontal until it reaches the downslope where it can do what it wants with little damage to the pond's structure.
Look at it like a picnic table. One side viewed from the end is in the pond, the table's top is like a plateau where water can flow but will not cause erosion. The other side is the outflow and once the water reaches where the table is sitting on the ground it can do little damage.
I would start with small rocks, 6-8" with many edges so that they will pile on top of each other and form a solid wall of resistance to water flow. So long as the inner wall of the pond at the spillway is solidly supported by this rock wall, flow and erosion of the wall will not likely occur. Bring the rock up to where you want your high water to spill over the spillway and then down the other side. Be careful in the plateau area to not cause too much resistance to flow with jagged rocks. This is a place with a good bed of smaller rocks, some larger ones, preferably flat or near flat, can be placed to keep the plateau from being washed downstream by unexpected storms or high water from snowmelt, etc. Same on the outlet side. Build a good base and then fill with larger rocks that are going to resist moving regardless of the volume of water flowing over, under or around. Had we used more anchoring rocks I might not have sustained so much of a washout as I did. When I re bolster the spillway, possibly this coming spring- when the rain stops and I find time, I will do just what I stated to alleviate further mishaps in future storms.

 

[20 20]

I wondered if ice would build up in the spillway in winter and cause late-winter of spring rain water to go around it?

I would not worry about the spill way freezing, for a couple of reasons. Running water doesn't freeze and the spill way is above ground so it would be 1st to thaw in spring, unlike a buried pipe. I have a pipe with the spill way over it, I'll see if I can find a diagram or something{???} I would think if you have big enough rocks and solid clay, maybe even mixed with straw{??}, backing them they would hold up well. Then mix in a crushed rock to help fill in and make a nice drivable top layer.

20_20 Is there a web site that has a pic or diagram of the the log arrangement? I understand you to say there would be two parallel logs going down the pond bank ? Is that to prevent erosion of the bank where the water enters the spillway?
Dave.

I'll do a search and see what I can come up with. The gentalman down the road that builds ponds for a living is the one who showed/told me what to do. The reason he has gone to this method is because of all the flooding we've been getting for the past few years{2006}. I like the straight culvert pipe for late spring and summer floods, but when everything is froze the spill way is a better deal{just my opinion}

 

[20 20]

Dave ,, Yes I would like to have just a spillway like you say,, but am too conserned with it freezing up and just overbanking somwhere else,,, I don't want pipe drain.. and don't have the down drop for the ^ shaped thing.. although nice idea,,

I just need to figure out how to install the spillway so it does it's job,,

Hr3; I'm planing on redoing one of my spill ways in the next couple of weeks. If you're interested I'll take some pictures while I'm doing it. This spill way is a simple one like what Dave1949 is suggesting{rocks}. The reason I am redoing it is because it is to narrow for what the "better half" wants . This spill way has been in place for over 5 years and I have never had one issue with it. It is also located in one of my ponds that does NOT have a culvert pipe. The SW on this pond does all the work spring thaw to summer flood.