Pond Boss Forums POND CONSTRUCTION Building a dam Pond dam piping Question?

Excavation will be starting in a few months on my pond and I still cant make up my mind on a type of primary discharge. I would like to have a bottom draw but the siphon at 12 inches will not be big enough. I am afraid of the amount of water that comes from the two springs that will feed the pond will be way too much for the 12in siphon and water will be going over an auxilary spillway with every storm. I excavated a small pond inline with the one spring just for baitfish and put in a 18in drop inlet and it flows full with every little storm. I was thinking of having SEPIPE build a inline riser for me. Is there any member on here with this type of discharge? The very few ponds in my area all have a drop inlet discharge or a earthen spillway.

Rockytopper has a substantial drop inlet on one of his ponds; I think it is the newest one. He'll check in. He had pics of it during installation...pretty impressive.
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Nick has a HUGE puddle with a drop inlet

BrianShpock, how do you know a 12" siphon isn't sufficient? Because of the increased velocity with a siphon I think you can use a smaller diameter than with a stand pipe. How big is your pond?

GW,
I have only an estimate from my figures with a transit and figure the pond will be around 1.6 acres. There is alot of water flowing into the area most of the year from the spring out of the side of the mountain. The one pond near where I am digging my puddle has a drop inlet (24in riser with 18in discharge) and it flows over the auxillary spillway with every storm. The aux. spillway is 24 in over the riser pipe.
I tried to get the NRCS guy to come out but he will not (after numerous promises of him showing up I gave up). I am just going on the advice of a DEP engineer I talked and he said a 12 in siphon system will not keep up due the the flow of the two springs.

Do you know the flow of the springs? If you want to balance this flow, you can do an estimate of the flow from the discharge pipe based on head pressure, discharge back pressure, and pipe size.

When I was designing my 6 acre pond, I found a siphon to standpipe chart that showed that a siphon handles better than 3 times as much water as the same size standpipe. I wish I had kept the link to it. I bet the guys at PondDamPiping can help.

Anyway, I have 320 acres of watershed, so I put in two 12" siphons. So far, I am convinced I could have gotten away with just one.

There is so much water running from the spring on the side of the mountain I just dont see a 12 inch pipe working. I have a 24in pipe where the spring feeds a small pond. and it is running half full this time of the year with no rain. there is another spring that will feed the pond also and it is flowing around the same. I am going to try and get a good flow rating of the two springs and determine what option I have.
Is it true you should not use a siphon unless you have a drop of atleast 4 feet from the inlet to the discharge?
I want some sort of bottom draw if possible.
I was thinking of a straight pipe through the dam with a riser on the backside of the dam with an alfalfa valve on the bottom to drain it if need be.
Trying to look at the pros and cons of each design.

I have a 42 inch drop structure with a 30 inch barrel. My water shed is 300 acres. Even this massive structure can't handle the gully washers we get in these parts. Mine is constructed from aluminum corrigated pipe. Cost was 8k installed. You can make a drop structure that draws off the bottom if you desire by making a larger pipe around the drop inlet that extends down to the depth you want to draw water from. It will also serve as a trash rack a very good one in fact.

Rocktopper,
That was one of my options. Having a hard time making a decision on which route to go. The way we keep getting hammered with snow and ice then rain, snow, and ice the ground may not start to dry til august around here. I have alot of time to make a decision. I am looking for input as to what others have and any associated problems with them or benefits.

Jersey I have seen your pond of course. With your water source in normal year there will be a couple of days a year I thihk you will be very glad you got the second pipe.

I haven't seen Jersey pond in person but if his 300 acre water shed flows any thing like the ones down in these parts he'll be dam glad he's got an emergency spillway. My 4.5 acre lake has 300 acres of water shed and 2 ft of catch capacity before it reaches the emergency spillway and will back water over about 6 or 8 acres. And my monster drop structure is still no match for the water that inflows during a 4 to 6 inch rain event.

I agree, Greg. I might only need both 12" siphons once or twice a year, but I'll be glad I have them. To the best of my knowledge, they have never gone into siphon mode yet. I plan to be out there in the torrent to see them when they do. With camera, of course.