Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? 10" Pond Siphon installed lil dissapointed...

Well the siphon system is installed and here are some picts of the installation. I ended up going with 10" because based on my calculations this should have been an increase of 880gpm over the exsisting standard 15" drain pipe. So 55 percent more flow. Well we had some flash flooding yesterday and I wasnt impressed. The water rose faster than I had ever seen it and I ended up spending 2hours trying to clear out the emergency spillway which looked like a river. So the question comes to this. Do I need more freeboard? Do I need to add a second siphon? Did the exsisting siphon not start early enough? Or did everything work fine and and I'm just not use to seeing the water go over the emergency spillway and thats what it's for? I just thought that with the size of the pipe I used being a siphon and only supporting about 70 acres of watershed It would handle a fast 2 or 3 inch rain fall. its only a 1.3 acre pond. I guess I'm a little dissapointed. I'll post some picts of the install and yesterdays test of the siphon when we got some flash flooding. Click on the link below for all the photos of construction and yesterdays event.

pond siphon photos and videos

The siphon looks great, but I think I'm missing something. I don't quite understand how your 10" siphon is giving you 880 GPM more than your 15" standpipe or drain. Does the 10" siphon have significantly more head?

This is all from the top of my head, as I haven't had to do this kind of work for a long time. But, every foot of vertical drop will only give you about 0.45 psi per foot, which is a major contributor to how much volume per second you can expect. With just gravity and a moderate drop of 10-20 feet, I would guess you are getting somewhere around a total of 1000-1200 GPM total with a 10" schedule 40 pipe -- unless you have something more in the system we aren't seeing. A 15 inch pipe, with the same head should be giving you somewhere around 2500-3000 GPM.

I think we need a little more info before we can give you an answer. Lastly, the bottom of your emergency spillway should probably be no less than level with your standpipe and sipon -- and probably several inches higher. If the emergency spillway is over-growing with plant material, think about adding several lengths of 8-16 inch corrugated drain pipe to it.

Thanks for the reply. The siphon intake has about 8 to 10 feet of head pressure on it. A 10” siphon will flow 2,480gpm with 8ft of head pressure. The old 15” drain pipe could flow a maximum of 1,600gpm with 1ft of head pressure. This would give me an increase of 55% in flow capacity compared to the original stand-pipe system. It was really shooting the water out, but just could not keep up with the inflow. With this size pipe I should be able to handle a 150 acre water shed. Not sure whats up there. My spillway is on the far right side of the dam and travels to the stream that is the discharge. It's considerably lower than where my siphon exits. It looks like someone just lined the entire thing with rip rap. I'm going to clear all the treebranches and junk out this week. Once the rain stopped the pond started to drop pretty quick and right now its back at normal pool just 13hrs later.

Here is a video of the amount of water I'm talking about. This was happening at the same time the 10" pipe was pumping out over 2000 gallons a minute. you tube pond overflow


Video of siphon working 10" siphon running video

Ahh. That clears up the water flow differences.

I lined the emergency overflow of my new smaller pond with 8-10 inch rip-rap. The dam is about 30' feet wide. This summer, I plan to add three 8-10 inch corrugated drain pipes on top of the riprap. It won't be a siphon, but the intake of the overflow pipes will be several inches below the main drain. The output will be even with the bottom of the emergency overflow intake. I'm hoping that will keep floating debris in the pond from getting into the pipes -- so even if water gets into the riprap that might be clogged with leaves and branches, there will be another path for the excess water.

The only problem I have now with the system is that the upper (smaller/newer) pond is supposed to be just a put-and-take pond. It has HBG, CC, RES, and FHMs. There is a stair-step riprap canal at the main drain, with about 8-9 dams over about 60-linear feet, with about 10-foot vertical drop, before it goes through a culvert. Then it goes through another series of seven settlement ponds, each of which have riprap at the intakes and outputs -- some with culverts. Much of the water from the last two ponds travels over grassy/wetland areas before reaching the main pond.

I've recently found that all of the settlement ponds now have hybrid hybrids. Some have apparently made it into the main pond and intermingled with the BG and REG. I now have fish I can't identify. They have mostly bluegill body coloring, but they also have yellow tipped fins. They have yellowish/orangish gill tabs. They are shaped far more like rock bass than bluegill or RES. They are extremely aggressive, and will take nearly anything thrown into the pond.

The only good thing so far is that they eat like crazy, they are growing like crazy, and they can be caught with virtually anything jigged at the end of the dock.

Mike -- I was just checking the weather to see what I can get outdoors in the next several days. This was at the top of the weather page:

Andrea Shatters Records: Raleigh to NYC to Boston

By Kristina Pydynowski, Senior Meteorologist
June 08, 2013; 5:11 PM

Numerous rainfall records were shattered, with flooding being triggered in the process, as Andrea moved up the East Coast on Friday.

Raleigh, New York City, Philadelphia and Boston are among the many communities (a full list is given below) that experienced their rainiest June 7 in recorded history on Friday.

Is it possible that this might have had some effect on your pond level?

I checked the weather report and it said we only got like 2.2inches in the 24hr period here in avondale. I checked the 1999 floyd hurricane and it dropped 8 inches. Thats what has me worried. If it cant handle 2inches how will it handle a 100 year storm. Maybe my rain totals are incorrect?

In my area, just 10 miles difference during the last storm was a difference of 1" rain. Go another 15 miles and the difference was 5" of rain.

I have a rain guage at the house and it rarely ever reads what was reported as the rainfall for this area.

Looks like you were right. They are now saying avondale had 4.20 in 24hrs. I think for now I will lower the air pipe so the siphon starts sooner. I also ordered a 4" ball valve so I can manually start the siphon if I want to draw down the pond some in the event of anouther hurricane or tropical storm. Next year after I save up some more money I will install a second 10" siphon right next to the one I have. This hopefully will be able to handle the big rain events. I think adding a foot or two to the dam wouldn't hurt either. I'm just dissapointed that I spent so much on this and it still will keep me up at night when the heavy stuff happens.