I am new to the forum and about to embark on the journey of renovating an existing 50-75 year old 1/2 acre pond. The existing drain pipe is clogged and the water is currently draining around the "emergency spillway". I plan to re-excavate the dam, install a new drain system, move the dam back, and enlarge the pond.
I have several questions pertaining to the riser pipe and valve.
1. I would like to use a standard vertical riser pipe with a trash rack. However, I would like to add a drain valve for future draw downs if necessary. I assume the valve would be located at the bottom of the riser pipe. I understand that it is recommended that these valves be worked 2-4 times per year to ensure their functionality. I have looked on the Pond Dam Piping, Ltd. website. However, it seems the stems on the valves they offer would not be long enough to operate at a depth of 12'-15' where this valve potentially would be installed on the riser pipe. Does anyone have a 12"-15" PVC riser pipe with a drain valve design that they could share? Specially, what type of valve, valve stem/handle, and connection would be best in this application?
2. What is the forum's experience with anti-seep collars? Should I insist that my contractor install at least one?
Welcome to the forum. Yes, at least one anti-seep collar should be used, more is better. Proper soil compaction under the pipe, around the pipe and on top of the pipe is critical too.
If the drain pipe is PVC and glued together, you can have the drain valve on the back side of the dam where it is easily accessible. If the pipe is 15' deep then the valve would see approximately 8psi pressure. If you are planning on using it to draw down the pond, then you will need a "T" where the riser is located to suck water from the bottom of the pond, and I would recommend putting a trash rack on that opening too. You don't want to get a turtle stuck in the pipe sometime in the future.
In my situation Installed two different pipes, a 4" diameter pipe at the very bottom, deepest spot in the damn for lowering the water level, and also for filling a tank for garden water, the actual overflow pipe is closer to the top of the dam with a concrete inlet or drop box much like a street drain inlet with the actual overflow pipe coming out the bottom of it. My valve for the 4" drain pipe is about ten ft before it exits the back of the dam so it is several ft underground to keep it from freezing. Good Luck, and welcome to the forum!
All the really good ideas I've ever had came to me while I was milking a cow.
I am not an expert on pond piping, but I believe most of the time the drain valve is installed on the horizontal leg of drain piping system - rather than on the bottom of the riser pipe. (That may be what your image is showing, but I couldn't open your image.)
I like the basic concept behind gehajake's installation in areas with significant freezing. However, that convenient valve location would not work if your overflow pipe and drain pipe both exit the pond in via the same pipe. Obviously, in that case the valve in the horizontal pipe leg must be upstream of the tee to the overflow pipe riser.
One option would be to use a sliding gate valve in deep water. You can add a long extension to the handle to operate the valve. Either mark the valve handle with a float and operate if from a boat, or locate the valve at the end of a dock so you can grab the handle extension.
One other thought - it pains me to "move the dam back" on a perfectly functional dam.
We all love bigger ponds but that seems like a lot of work, expense, and risk to expand an existing pond.
Any chance you could just build your "new" dam at a location farther downstream in your waterway? For many uses, two 1/2-acre ponds might be better than one 3/4-acre pond.
Unless of course, you have a perfect development plan in your head for your new expanded pond. However, a new dam for a 1/2-acre pond may yield you more total water impounded for less cost than building a bigger dam for the expanded pond project. (I am just throwing out ideas while you are still in the planning phase.)
Understood in regards to the anti-seep collars and compaction.
Understood regarding the tee when installing the draw down valve on the horizontal outlet pipe in front of the embankment/dam.
Understood on installing a trash rack on the inlet side of the draw down valve.
However, assuming a conventional riser pipe design I am having trouble understanding putting the valve on the outlet side of the horizontal pipe. If the valve is placed on the outlet side of the horizontal outlet pipe and if the valve is closed how would the pond drain? Would I have ensure the valve is opened to the correct position to ensure the water level in the pond remains at the desired level?
Yes, I am currently proposing to install the drain valve on the end of the tee on the horizontal drain pipe in front of the embankment/dam. This valve would be in deep water. Currently I plan to build a dock to be able to access the gate valve handle. But I guess this is where I have questions. It seems the typical valve handle lengths that are sold by most companies are 4', 6', 8', etc. If this valve is located in 12'-15' of water how would I operate the valve? As some have suggested, would I tie a rope to the handle and attach a float to the rope to enable the operation of the valve? It seems overtime the rope would rot. Are there other suggestions? Do these sliding gate valves slide back down to the closed position on their own? Or must they be pushed back down to the closed position? As an additional resource, I guess I could call the valve manufacturer or vendor to get further suggestions?
This 50-75 year old dam and corrugated metal principal spillway is currently not functioning properly. Due to a blocked principal spillway, all water is currently draining around to the "emergency spillway". No water is existing through the principal spillway to the preexisting creek channel. I estimate I would have to remove at least 2/3 of the existing dam to remove the existing drain pipe to replace and repair it. Since approximately 2/3 of the dam would need to be removed to make the necessary repairs my thought is that this would be the time to de-muck and move the dam back to enlarge the existing pond.
O.K., now I understand your question. The gate valve on the back of the dam won't work. The "T" handle needs to be pushed back down, so a rope won't work for that. You could use a rope to open it, and a piece of PVC pipe or something else solid to push down on the top of the handle to close it.
I agree with esshup's comment above about operating a deepwater valve. I have asked buddies about it after seeing a float beside the dock. However, I did not ask them how well that system was operating.
What is the diameter of your current outlet pipe? Knowing the size somewhat affects valve choices, the pricing of alternatives, etc.
Also, do you live at the pond location, or will it be remote from your house?
I ask on that one, because you can also set the level of a pond by setting the elevation of the lip of the OUTLET pipe.
One way is a turn-down pipe. That allows you to rotate the outlet pipe 90 degrees to drain the pond - and no valve is needed. However, that is risky because if your moveable connection ever pops free, then your pond will drain!
Alternatively, you could also do it with an inground valve (like gehajake's setup) and a tee to the outlet riser and a second valve in the horizontal of the tee. Your outlet riser pipe needs to be protected by a frame, rock gabion basket, etc., with the top lip set at the normal pool elevation of your pond. The valve in the ground stays open, and the valve at the tee stays closed during normal operations. After a rain event, water will flow out of the top of the outlet riser until the level of the pond recedes to the level of the top of that riser.
During winter, you close the valve in the ground, and open the valve at the tee to have only air in the freeze susceptible portion of the line. This will work if you live at the farm and can open the system if there is a surprise winter storm. Or if your emergency spillway is trustworthy enough to handle your winter precipitation.
When you want to drain the pond, you just open the valve by the outlet tee and pull down the pond to your desired level.
