A mild late-January Saturday meant a long-overdue trip to Roundrock. Libby and I (and the dogs) hauled our fine selves down there with the full intent of enjoying the respite from winter.
Unfortunately, that “enjoyment” first involved a long-overdue chore — beginning to fix the hole gouged out of the northern spillway by the big water event a little more than a month ago. When this happened before, the dozer man said it didn’t look too bad. He repaired it. I paid him. Sowed some grass seed. Crossed my fingers. And sat back. Then it happened again. (As I documented here.)
The gouge that the water took out of the spillway (both times) had crept all the way up and onto the flat bit at the top. Had it continued another 20 feet, it would have been a breach, and I might have lost the lake altogether. While there is not likely to be any big water events at least until the spring, I didn’t like the idea of that trench in the spillway sitting so close to the water. (The southern spillway was just as destroyed, but the top part is bedrock, so it’s not going to present a threat if there is more water. There is no dangerous trench at the top.) Thus the chore.
One technique I had read about for this kind of thing was to place cut cedar trees in the trench, with their stumps pointing downhill. The idea is that as mud and bits of gravel wash into and down the trench, they will get trapped in the leaves and branches of the cedars (those being aligned uphill to do the catching), and in this way at least partly fill the hole.
Since I have a lifetime supply of small cedar trees (several lifetimes), I decided to put that resource to use. I first got busy cutting down likely cedars in the area and then throwing them in the trench, properly aligned. It didn’t take long to get this part of the work done.
Here is what I managed to do:
Sorry about the goofy angle of the shot. That’s the lake at about 2:00; the spillway runs downhill at 9:00. It’s hard to tell from this photo, but there are dozens of cedars in there, and that’s just the uppermost part of the trench that I “filled.”
Then came the real work of the morning: throwing rocks onto the cedars, both to hold them in place and to begin filling the trench with some substance that won’t wash away in a light rain.
Fortunately, I have lots of rocks in my Ozark forest as well. Many of them were in the trench, albeit washed downhill a bit (from more than a light rain). All I had to do was bring them up from below.
Here is my supply:
You can get a pretty good sense of the damage done and the work to do. Those cedars in the lower right are the ones you see in the photo immediately above; that’s the top of the trench. The trench itself meanders down the hill, bounding around some exposed bedrock. There is/was a berm running down the right side of this spillway, and though it wasn’t completely cut through, it’s as good as gone in a couple of places. The orange soil you see at the bottom of the photo is the kind of clayish dirt that I’ve been told is not desirable for dams. I don’t know how much of my dam is comprised of this, but the fact that it leaks after a decade of silting in suggests I have too much.
My original plan was to take the wheelbarrow down the hill, fill it with rocks, then push it back up the spillway to the top where the cedars are, dumping it and slowly filling the trench. Unfortunately, there wasn’t enuf open, flat surface left of the spillway to get the wheelbarrow down to where the bigger rocks were. Well, I could get it down there because it would be empty and nimble. But filled with rocks, it would have been a challenge just to get it up a hill, never mind the rubble-strewn tightrope walk I’d have to do in some places. So the wheelbarrow stayed at the top of the spillway, serving as a handy receptacle for the tools I wasn’t using and the the clothes I was shedding as the work progressed.
Instead I carried the rocks up, mostly one at a time, in my arms. Rocks the size of basketballs in most cases. I had started throwing smaller rocks at the problem, but they passed right through the branches of the cedars and clinked smartly against the rocks in the bottom of the trench. That was filling the space, but it wouldn’t have held the cedars in place when any flow did come along. So I switched to the bigger rocks. The bigger, heavier rocks. Most of which were nearer the bottom of the spillway than the top.
Trudging up and down that spillway twenty or thirty times was not difficult; I am a runner and have legs and lungs at least partially conditioned for that. But upper body strength hasn’t been a big part of my training. Long before I made a recognizable difference in the yawing emptiness of the trench at the top, my arms and shoulders were telling me they’d had enuf. But I persevered. Because cross training, right?
After a couple of hours, I finally decided I’d done enuf. Libby and the dogs had long-since stopped supervising and had gone back up to the cabin. Here is the state of things when I left:
I’d say I have about a third of the hole at the top of the spillway filled. Maybe less since the sides slope outward, so more rocks would be needed at the top than at the bottom.
I gleaned all of the good rocks from within reasonable reach. The remainder were either smallish or they were too large for me to lift/move up the hill. There is no shortage of rocks in the Ozarks. And I could probably put in another layer of cedars atop the rocks that are in there.
I’m sure to get this job finished I’m going to need to hire someone with a big machine to fill the remaining space. And I suppose I will, but unless I can get an insanely dense crop of grass growing on that rocky spillway (which is to say, I can’t), I will likely see another washout sometime in the future.
My goal, now, is to fill the trench near the top and as far down as I can (through muscle power or machine power), and then have a slab of concrete laid over it. In this way, even a big water event will pass over the top of the spillway without eroding anything close to the dam and the lake full of water behind it. Beyond that, I think the spillway is far enuf away from the dam that any erosion, while ugly, won’t be a structural threat.
On our way out that afternoon, I stopped at Good Neighbor Dave’s place. He has a lake much the size of mine, and years ago he had poured some concrete at the top of the spillway to check the erosion. Dave happened to be at his property that afternoon, and we walked across his dam to the spillway, chatting about what he did, what it fixed, how it worked, and what it cost. His solution is different from what I want to do, but my set up is better. He had to persuade the concrete truck driver to back all the way across his narrow dam to where the spillway is. In my case, a truck would still be on my wide road, actually above the dam a few feet, when it poured. And Good Neighbor Dave got the job done. For a reasonable price. I think I can too. I just need to save my pennies and hope the work I’ve already done isn’t lost in the meantime.