Hi all, I'm new here and am hoping someone can point me in the right direction. I am managing a pond that has a spillway design for lowering or increasing the water level in order to manage a wetland below the dam. Unfortunately there are currently no stop logs and due to the design I am stumped on what material I need to use for the stop logs . The channel the stop logs slide down on each side is tapered (3 1/4" thick on the outside and 3 5/8" on the inside) The entire structure is 5' tall and 32 1/2 inches accross. I was not expecting a tapered design and really don't know what material I need to use to properly dam up the structure and ensure I can easily get the stop logs in and out. Any help would be appreciated. Thanks! Aaron
Very interesting design. It looks like there is a wedge installed on each end at the pond side. I wonder if you could source this from somebody with a mill straight from a log. You'd be able to basically buy the log and pick the dimensions of the board you want be it 6-24"
Yes I used cedar wedges to snug up the fit, you dont want the board the thickness of the groove or it'll swell up and you wont be able to get them out or adjust them. I also ship lap jointed them. The water barely trickles out the seems and joints when the level is below the overflow.
Does your design have to hold water perfectly, or can it leak a little water? For example, is there some rate of water flow out of the wetland, so if you restrict the water flow to a trickle at the stop logs, then that will manage the water level in the wetland? (Good is MUCH easier than perfect.)
Tinylake operates a similar system of stop logs so I would heed his advice. I think his most important advice is that the boards will swell as they absorb water!
I also agree with the ship lap joints, that should significantly reduce your water flow through the boards.
Finally, you do NOT need your stop boards to match your groove thickness. Get the most readily available thickness that will serve your purpose. (Probably 1-3/4" thick. Does Canadian dimensional lumber match U.S. dimensional lumber, but just measured in metric?)
After your install your stop boards, you can then just hold them in place with your "pin board". (Sorry, I can't remember the correct name.) Get that piece to the correct thickness to also fit inside your grooves with a little gap. Turn that board so that the long dimension is vertical and it can pin all of your stop boards in place! (It should be a little higher than your highest stop board when installed.) Then pound in two wedges to hold it in place like Tinylake's picture.
The top wedge needs to be ABOVE the water level at full pool. For removal, you can then easily knock out the top wedge and then wiggle the pin board to loosen the bottom wedge.
P.S. If there can be zero trickle, then you may need to make your board dimensions a little smaller and put some compressible rubber(?) material between the stop boards and the downstream edge of the groove, so it will really seal when all of your boards are wedged into place.
I wouldn’t use oak. It has tannins that are lethal to fish. When I first built my pond, I had a bunch of oak trees that had been pushed. I stacked them in the bowl for structure. Rain came, the pond filled and I stocked. The water turned black and all the fish died. I found that tannins are lethal.
I know nothing about white oak. Test it by cutting a log by putting it in a tub of water. Add fish and see what happens in a couple of weeks.
I had to drain the pond, remove the oaks and start doing a rain dance.
I prefer cedar
Last edited by Dave Davidson1; 08/10/2404:56 AM.
It's not about the fish. It's about the pond. Take care of the pond and the fish will be fine. PB subscriber since before it was in color.
Without a sense of urgency, Nothing ever gets done.
Boy, if I say "sic em", you'd better look for something to bite. Sam Shelley Rancher and Farmer Muleshoe Texas 1892-1985 RIP Grandpa
Interesting, my whole 400 acres is red oak, lake surrounded by red oak, leaves from red oak in the water, dead oak trees in the water, beavers cut and drag red oak into the lake....that being said most large weirs here are made of douglas fir - which really leach out.
Sorry took so long to get back to you all, life got a little crazy past couple of weeks. First off thanks for taking the time to point me in the right direction, this information is much appreciated. The pond doesn't need to be perfectly sealed, but I would like to get it as close as I can. I did managed to get my hands on some old bridge planks that will need to be cut to fit. My question is how much of a gap will I need for swelling? Is 1/4 inch enough or should I leave more?
Hard to say on old bridge planks. They might be so age-hardened that they don't swell all that much?
I think you need to err on the side of the gap being too small. If they really swell, you should still be able to gently tap them out with a baby sledge hammer. If that was a ton of work, then take a little more off for your final gaps.
In my carpentry experience I have found that it is much more difficult to make wood longer!
