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Joined: May 2014
Posts: 3,864 Likes: 298
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OP
Joined: May 2014
Posts: 3,864 Likes: 298 |
Water went over my emergency spillway for the first time a few days ago. MAJOR erosion despite pretty well established grass I know that something must be done. Two or three more events like this would undermine the whole dam! Any suggestions? Concrete? Rocks?
7ac 2015 CNBG RES FHM 2016 TP FLMB 2017 NLMB GSH L 2018 TP & 70 HSB PK 2019 TP RBT 2020 TFS TP 25 HSB 250 F1,L,RBT -206 2021 TFS TP GSH L,-312 2022 GSH TP CR TFS RBT -234, 2023 BG TP TFS NLMB, -160
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Joined: Oct 2013
Posts: 6,088 Likes: 96
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Joined: Oct 2013
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Good article covering your problem in Pond Boss Magazine Mar/Apr issue, page 48.
John
I subscribe to Pond Boss Magazine
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Joined: Oct 2015
Posts: 2,424 Likes: 19
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Joined: Oct 2015
Posts: 2,424 Likes: 19 |
A pond owner I met stopped this problem by putting about a ton of steel shavings from a machine shop in his emergency spillway. He had previously tried bagged concrete. The shavings are heavier than concrete and kind of interlock together. You could probably buy at scrap steel price, now about $100/ton. I know it's a wild sounding suggestion, but it works very well. His pond has excess watershed.
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Joined: Sep 2014
Posts: 3,668 Likes: 57
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Joined: Sep 2014
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Frank, sorry to hear that. We have seen some crazy rain amounts last years spring and this year. What do the big boys say ?
Tracy
Do not judge me by the politicians in my City, State or Federal Government.
Tracy
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Joined: Feb 2014
Posts: 109
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Joined: Feb 2014
Posts: 109 |
I have concrete over our spillway. At times, we have 2 feet of water flowing over it. Works like a charm! Definitely not the least expensive route but if you want something there that youll never have to worry about then its a for sure fix. Alternatively, you could probably put some large (4-5in) rock but once again you risk it not being enough
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Joined: May 2014
Posts: 3,864 Likes: 298
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OP
Joined: May 2014
Posts: 3,864 Likes: 298 |
Thanks for the advice, guys. I've scheduled a meet with my construction guy, looks like concrete would be best. Got a pretty big watershed for the size of the pond, and a creek that flows constantly regardless of the weather.
John F, I assume the steel shavings were mixed into the concrete to make it heavier & thus more stable, right?
On the plus side, the water has cleared up, vis now about 24 inches. Fish are feeding very well, I can see different sizes of BG and FHM. And button bush are growing like gangbusters, what a plant for shoreline and erosion!
Last edited by anthropic; 05/04/16 11:23 AM.
7ac 2015 CNBG RES FHM 2016 TP FLMB 2017 NLMB GSH L 2018 TP & 70 HSB PK 2019 TP RBT 2020 TFS TP 25 HSB 250 F1,L,RBT -206 2021 TFS TP GSH L,-312 2022 GSH TP CR TFS RBT -234, 2023 BG TP TFS NLMB, -160
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Joined: Jun 2015
Posts: 165
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Joined: Jun 2015
Posts: 165 |
I know a person would have to have the topography to support it, but my overflow pipe is actually in the drainage ditch that feeds my pond. once my pond is full and starts backing up the drainage ditch, it can flow out the side of it.
Small pond, and probably not something most folks can do, but seems it would avoid a washout of a damn.
Sean
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Joined: Jan 2009
Posts: 28,513 Likes: 831
Moderator Ambassador Field Correspondent Lunker
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Moderator Ambassador Field Correspondent Lunker
Joined: Jan 2009
Posts: 28,513 Likes: 831 |
Erosion is caused by the speed of the water flow. If the emergency spillway can be made wider and the drop (slope) reduced, the erosion will be minimized if the speed of the water flow is reduced. If the speed of the water flow isn't reduced, it has to be lined with something that won't erode, and something that the water can't get under. Some concrete spillways have had undercutting issues from water falling off the concrete at the end, removing soil, and working it's way back under the concrete.......
I agree about the good article in the magazine.
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Joined: Oct 2015
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Joined: Oct 2015
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John F, I assume the steel shavings were mixed into the concrete to make it heavier & thus more stable, right?
No, the shavings are not embedded in anything, and are in a wide row across the spillway a few inches deep. The water percolates through them. Beats anything I ever saw for erosion control.
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Joined: May 2014
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Joined: May 2014
Posts: 3,864 Likes: 298 |
Anybody use them? My dirt guy wants to use rip rap in the spillway to stop further erosion, but from what I read gabions (chickenwire) keep the rocks in place much better during a water event than just individual rocks.
Feedback?
7ac 2015 CNBG RES FHM 2016 TP FLMB 2017 NLMB GSH L 2018 TP & 70 HSB PK 2019 TP RBT 2020 TFS TP 25 HSB 250 F1,L,RBT -206 2021 TFS TP GSH L,-312 2022 GSH TP CR TFS RBT -234, 2023 BG TP TFS NLMB, -160
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Joined: Oct 2014
Posts: 6,080 Likes: 1
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Joined: Oct 2014
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FWIW they had to replace the patio at our new place due to cracks. When they tore up the first effort they produced large broken slabs with many still connected by the reinforcing wire. For me, it was a PITA cause I wanted to use the broken slab in the pond as habitat and spent hours clipping and removing the reinforcing wire. In your case, the broken up stuff with the wire intact might be just the ticket. Some of my pieces were 100+ pounds each and the wire should work the same as chicken wire but last a whole bunch longer. A call to a few concrete contractors might get you broken slab for free....maybe make it a little bit prettier with a thin layer of large rip rap on top......
Just a crazy idea....
Last edited by Bill D.; 05/06/16 08:40 PM.
Be Brave Enough to Suck at Something New!
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Joined: Jan 2009
Posts: 28,513 Likes: 831
Moderator Ambassador Field Correspondent Lunker
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Moderator Ambassador Field Correspondent Lunker
Joined: Jan 2009
Posts: 28,513 Likes: 831 |
Anybody use them? My dirt guy wants to use rip rap in the spillway to stop further erosion, but from what I read gabions (chickenwire) keep the rocks in place much better during a water event than just individual rocks.
Feedback? I've seen some pretty big rip-rap washed away in an emergency spillway. I've never seen the gabions washed away. Put thick geotextile fabric (available from WhiteCap Supply) under them to prevent the dirt under them from being washed away, if that happens, that might allow the gabions to drop down or move around if their "foundation" is moved.
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Joined: May 2014
Posts: 3,864 Likes: 298
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OP
Joined: May 2014
Posts: 3,864 Likes: 298 |
7ac 2015 CNBG RES FHM 2016 TP FLMB 2017 NLMB GSH L 2018 TP & 70 HSB PK 2019 TP RBT 2020 TFS TP 25 HSB 250 F1,L,RBT -206 2021 TFS TP GSH L,-312 2022 GSH TP CR TFS RBT -234, 2023 BG TP TFS NLMB, -160
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