This is a 20 yr old community pond and it's about 10 acres. When we get a lot of rain the pond floods pretty badly, putting the fixed parts of the dock/gazebo, my fish feeders and much of the shoreline trail I built under water.
I was not around when the pond was built so I'm not sure who decided to build it this way, but common sense tells me that the reason the water gets so high is at least in part because the riser has this solid steel cover on it as opposed to more of a grate / rebar construction that would allow a lot more water to drain. The holes around the top of the riser, in conjunction with the spillway, have not been adequate to prevent this flooding. This happens a few times every year.
Wondering if this was done to minimize strain on the riser to reduce risk of failure.
Is there an expert on here with experience building ponds / risers? I would like to petition the other owners to replace this solid cover with a design that would allow a lot more water to drain but I need some ammunition.
Any advice or resources would be most appreciated.
See attached picture of existing and of a design that would allow for a lot more drainage.
Last edited by Steve Grasberger; 06/17/2509:52 AM.
Sometimes the "solid cover" design is actually just an oversized pipe that extends a few feet below the water level. Its purpose is for "bottom water" to exit through the outlet piping.
Surface water is preferred to selectively remain in the pond because it is the oxygenated part of the water column. Also, floating debris such as leaves, pine needles, and floating branches after storms are (mostly) kept away from the actual outlet pipe by this type of design.
Everything said above is pure speculation!
However, there are ways you can check. Can you observe the pond outlet on the downstream side of the dam? If so, is it the same diameter as the pipe you observe in the pond, or is it smaller?
Do you have easy boat access to the pond? If so, you might take a long hook and probe around the solid cover and determine if there is a lower lip that is above the bottom of your pond.
Generally, the surface area of the annulus (the area between the two rings of pipe) in this type of design is greater than the surface area of the interior pipe. If my speculation is correct(?), then removing the solid cover would NOT increase the flow rate. The actual limiting factor would be the area of the interior pipe.
Finally, ALL designs can encounter some plugging. Is there a way to remove the top plate on that cover? If so, I would get permission to remove it and examine the situation to determine if there are some obstructions.
IF, the pond is flooding more frequently now, AND you are not receiving record rains, then something has changed about the drainage outlet!
Good luck on keeping your community pond in tip-top shape!
