Pond Boss Forums POND CONSTRUCTION Building a dam What if my spillway pipe is plugged?

Just cuz that's how my life goes, I want to throw this scenario out there to make sure I have considered all the contingencies.
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We installed an 18" dia corrugated pipe for the principal spillway. It runs 120' feet underground; through the dam and back slope. It was installed 18 months ago. There are no critter guards on either end. We may very well see the pond level rise to the spillway this winter/spring.
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What are the chances that some critter built themselves a nice little tube crib? Or, more importantly, what are the chances that a tube crib would jam and plug up the pipe during the first water flow? OK...and more important than that...if it does jam, how does one clear it out?
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a couple of thoughts:
a) I do understand the mortal danger of working near the intake end of a functioning culvert, particularly a plugged culvert
b) we do have an emergency spillway that should handle the overflow without issue
c) the first 20' and the last 20' of the 18" spillway pipe is dual wall, smooth core. The 80' in between is single wall corrugated.

If a critter is in there the water will force them out quick.

Why not? Are you considering them?

I installed a rat guard on the outflow the day after the pipe was installed and a trash rack on the spillway pipe a few days later.

For an 18" dia horizontal principal spillway, I would not install a trash guard. It would be the first reason to create a clog with junk that would likely pass thru the pipe. We did install a hooded inlet that will eliminate a potential vortex and will keep larger logs and objects away from the pipe.

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I considered installing a rat guard at the downstream/outlet end, but nix'd it as being futile since the other end was open.

B-ski I've already said this but I'll repeat my self again. You need a trash rack on your intake. Yes it can clog as your contractor stated but it can be easily cleaned. If something of size gets sucked down the pipe and it jams some 100 ft under your dam well call the track hoe out and start digging. Your emergency spillway will carry the water as you've stated if the trash rack every clogs. If the trash rack is designed so that it can draw water underneath it then the pipe will flow even if the rack gets clogged with debris. Just my 2 cents. It's your plumbing do as your wish.
By the way how many sq ft you want it and will it be 1,1.5, 2, or 3 stories? 4?

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Thanks Rocky-T...very good points and thoughts. That's why I'm throwin' it out there for review.
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IMPORTANT NOTE; I am an absentee pondmeister, so monitoring will not be convenient.
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Any other thoughts from the experts and experienced? I could easily fabricate a guard to attach to the existing hood structure. If I did, what would one use for spacing between the grate rods? Are there any unforeseen problems that I might encounter by installing a trash rack/guard?

Brettski, here is what we have on ours.

Rocktopper beautiful artwork! Brettski I would definitely install some piping around that inlet. I will tell you a short story and bad ending. My fathers uncle had (remember the word had) a 3 acre pond on his hunting farm. Approx 8 years ago we had a quick snow and ice melt after a 24 in snow storm and he had a discharge pipe like yours installed with 36 inch corrugated metal approx 60' long. The lake was 26 foot deep at the breast. During the fast thaw there was alot of wind. Numerous limbs had jammed up the pipe going through the breast about 25 foot inside. There was so much pressure with the water flowing through the pipe that the limbs actually ruptured the pipe and the water started to erode the bank from inside the pipe. Needless to say the dam ruptured and all the water ran out flooding a campground a mile down the road. The camp ground was a winter storage area for numerous Fifth Wheel campers and motor homes that were flipped over on there roofs . Luckily for my dads uncle he had insurance but he had told me there were over $750000 in claims filed over the mess. The funny thing was the water never made it to the emergency spillway. I still remember going to the farm and thinking were did all the 6 pound bass go.
DEP made him either make the dam to their specification which cost way too much or make a smaller dam. The place still isnt the same fishery as it was back then.

I recently stocked Grass Carp for a guy. The State of Texas made me put a fish excluder (barrier) over the overflow. It is 2' x 4" hog wire paneling. It is their thought that 2 x 4 is large enough to keep from stopping up but should keep the amur from escaping. The darn thing should also keep limbs and varmits out. I sweat bullets anytime I constrict an overflow.

Brettski:

I'd also definitely install some type of cage. Make it out of cattle panels, 6"x6" openings and as big as you want. It'll stop brush (and small children) from getting sucked up against that pipe.

Had a buddy's pipe get plugged by a large snapping turtle...took a couple days with a 20' pipe and lots of bashing to get it broken up enough to come out. Luckily, no huge rain events before we got it taken care of. Obviously...take a heckuva a turtle to plug yours, but an animal carcass (deer?) would do the same thing, perhaps.

I've got to assemble one tonight for my north pond (6" pipe)...thanks for the reminder.

With an 18" pipe you'll have no worries.Get a bowling ball,core it out and keep it on hand.When you get a plugged situation,simply pack the ball with c4,roll it into the pipe and when it rolls to the plug,detonate it...viola... no more plug

I guys have me just about talked into putting another one-sided trash guard on the 8" drain on my new pond. And I just explained to my wife why I wasn't going to put one on this pond.

Yeah, I'm already engineering the trash rack on mine, too. It's absence doesn't bother me until I think about:

Rocky-T reminds:

At 18" dia x 120 feet long, I have difficulty envisioning myself crawling in to dislodge the object. I have considered R/T airfare from Lincoln + lodging and meals, but I don't believe that Bruce's arms are quite long enough (besides, the pipe has a slight curvature and Theo has revealed the truth; that Bruce doesn't really have elbows).

I actually don't have a primary elbow, per se. It's really a series of small bendable junctions known as flexions. It sort of gives a "slinky" effect.

"It sort of gives a "slinky" effect."

Well, all I can say is I hope no one tries to push you down a staircase!'''

'''taken from TOMG's medical solutions post.

Don't be ridiculous. Donna-ski is a lot smaller than you are.

I've been waiting for the TRASH rack TALK to begin.

I'm really proud of my Frank Loyd Wright trash rack design Bski. Notice the way I blinded it in to it's environment. You'll never even know it's a add on.

Okay, I asked Mike Otto about trash guards on spillway pipes while at the Moderator's retreat.

Otto said pipes from 24" and up in size are pretty hard to stop up. But smaller pipes, certainly ones in the 8"-12" range, definitely should have some protection to keep sticks, animals, too many leaves, etc. from entering them and getting stuck.

NOTE: I believe that such trash guards should be constructed in a manner so that if the trash guard itself becomes clogged, water can still reach the drain pipe in order to leave the pond and prevent a dam breach.

Anyway, I will be putting some kind of fail-safe trash guard on the drain pipe of my new pond before the water gets another 3 feet higher and she's full.

Uh...just talked to a buddy with a 36" pipe on his pond. Last time it stopped up, it had a 30 gal barrel stuck down in it. They got it out, but never installed a trash guard. Now, it's stopped up again, but the top's under 3 feet of water, with 8 inches of ice over that.

Water's been running over the spillway since first week of December. It'll continue to do so until evaporation or a dam breach lowers the water level far enough to fix the problem.

He told me he's already moved his "shite" out of the way...figures a wet spring and the worst will happen.

I've got 14 below zero this morning. I'm a pretty smart guy, tho...I have been putting off installing my trash guard until warmer weather. I did it yesterday. It was much warmer at 5 above with 20 mph winds. D-ski stayed home. Whassup wit dat? Anyway, Rocky-T busted my will. I think he will approve of the final trash-guard product. No pix, tho; too cold. Maybe next week.
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This link will take you to the before and after of the principal spillway pipe/trash guard results
Hooded Inlet thread