Pond Issue....

[skipperbrown]

4 years ago we had what the experts are calling a 500 year flood. Hundreds of home that were not in a flood zone were flooded (and got no, zero, nada insurance reimbursement for their flood damage. The flood opened my eyes to what can happen when you get too much rain. Make sure you can handle at least a 100 yr flood and also be cognizant of what might happen downstream if your pond releases all its water at once. You could be held liable for someone's loss/damage of property or livestock. I would start with a call to your county extension agent.

 

[MossRoad]

If it overfilled with an 18" overfill pipe enough to top the dam, then you need a larger overfill pipe for starters. You had no emergency spillway, either. There should always be an emergency spillway. You're putting one in, but what do you know about sizing it? And the overflow pipe, too, for that matter. As others have mentioned, best to consult an expert, especially if there's anyone else's property downstream that could be impacted if your dam breaches.

 

[neopheous]

If it overfilled with an 18" overfill pipe enough to top the dam, then you need a larger overfill pipe for starters. You had no emergency spillway, either. There should always be an emergency spillway. You're putting one in, but what do you know about sizing it? And the overflow pipe, too, for that matter. As others have mentioned, best to consult an expert, especially if there's anyone else's property downstream that could be impacted if your dam breaches.

Thanks.... concerning the mention of should the dam fail in the last couple of posts, and what is downstream... There is the main creek that runs along the road (dirt, with very little traffic... if I am at the property for 8-10 hrs I may see 2-3 cars and one of those is the mail carrier.) That creek/road is about 75-80 yards from the dam, and then downstream of that I own along the road on the pond side for probably close to a 1/2 a mile. Beyond that it is just pasture for the next 2 miles... the pond is approx. 1/4 acre so I am not too concerned should it fail and where the water goes, as it should just flow to the creek and empty out from there..., other than I definitely don't want it to fail!

 

[MossRoad]

Just be aware of the power of moving water.....

Here's a horror story from a 3 acre beaver pond that broke...

Flood waters rush in Duvall after beaver dam break | KOMO

 

[neopheous]

Just be aware of the power of moving water.....

Here's a horror story from a 3 acre beaver pond that broke...

Flood waters rush in Duvall after beaver dam break | KOMO

Understood, although that it at least 12x larger than my pond, possibly more depending on the depth, not to mention sitting evidently right above homes..... plus a dam built from sticks and logs plus a little bit of mud rather than compacted clay.... but I do realize even those sort of dams have failed before.

 

[philbuilt]

Do you have the option to put the spillway on the other end wa
Where the water is coming from. That would solve 2 issues, one water level controll and you could remove your over flow pipe. That’s how I controll my pond. High side inlet creates consitant water level and prevents lower dam washouts. If that’s not possible eliminate the pipe and do a wide and long spillway with integral creek bed

 

[neopheous]

Do you have the option to put the spillway on the other end wa
Where the water is coming from. That would solve 2 issues, one water level controll and you could remove your over flow pipe. That痴 how I controll my pond. High side inlet creates consitant water level and prevents lower dam washouts. If that痴 not possible eliminate the pipe and do a wide and long spillway with integral creek bed

Phil, I wish... but I do not see anyway since it is all higher elevation... see attached below:

 

[philbuilt]

Can you give us a google earth image? Your spillway will work as you have it in the pictures just make sure it is wide and a slope of 1/8” per foot. Water needs to move over it but not fast. Make sure to grow grass to help eliminate washout. I’m a fan of natural drainage not pipes. Put a small creek bed in the spillway and get rid of that pipe. Looks to me like you could raise the water level another 18”.

Just my thoughts
Phil

 

[rekees4300]

There should always be an emergency spillway.

DITTO ... No matter how much it rains the water must NEVER top the dam or it will be like a knife slicing through hot butter. In addition to proper overflow pipe sizing, pipe blocking from debris needs to be prevented. I use a device called a bar guard.

View attachment 543778

 

[neopheous]

Can you give us a google earth image? Your spillway will work as you have it in the pictures just make sure it is wide and a slope of 1/8” per foot. Water needs to move over it but not fast. Make sure to grow grass to help eliminate washout. I’m a fan of natural drainage not pipes. Put a small creek bed in the spillway and get rid of that pipe. Looks to me like you could raise the water level another 18”.

Just my thoughts
Phil

Phil, I like that idea as well. So, let me make sure I understand what you’re saying. So the emergency spillway that I have highlighted is that what you are saying should be 1/8 in drop per ft? And I had already planned to immediately sow it it with perineal rye grass and fescue. But you also mention removing the pipe and making a spillway there also over the dam in its place? That’s a much steeper drop and I see no way to make a slow descent. I was just going to make a concrete and rock tail race under the pipe. Or are you saying just remove the pipe and build up the dam in its place and then use what I call the emergency spillway as the sole outlet for the pond? If so I would assume it needs to be at least 10’ wide, plus b/c of the lack of freeboard I have it could be close to 2-3 ft deep by the time it reaches the ravine that I plan on running it to.