I could make my digital leveling project go much faster if I could run the level across the exposed tidal mudflat. I'm thinking I could drive 3?ÿ 2"x4"x30"?ÿ "piles" to set the tripod on. Anybody ever try that before???
Sounds like it could work, but what depth you need the piles will depend on how solid the mud is underneath.
Yeah, I agree. I'll need to experiment with pile length before we do the actual survey next Spring.
How many change points would you require and does 'driving' those piles save you the extra time also with walking in swamps or mudflats the speeds slows dramatically...
Ever tried walking across a mudflat?
It isnt always easy.
Could very well be slower than going around...
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I have tried similar a good number of times, usually it fails and is miserable. When it works it is somewhat less miserable, don't forget that you need someplace to stand without disturbing operations.
Years ago someone here or there shared pictures of their "swamp legs" a special tripod that could get an HI of eight free on dry land.?ÿ
Right you are, Jim. When my older twin was earning his marine biology degree, his greatest interest was in estuaries. (Of course, he always liked mud when he was growing up.) His settled-on attire for chasing critters in the mud flats around Wilmington, NC was the same as a concrete worker's attire. He may have lost a boot to the mud; I don't remember exactly. It was always slow going and big cleanup afterwards.
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Thanks for all the thoughts. I have walked on the route I might try and only sank down about an inch so I'm hoping it will go ok.?ÿ
There will probably be 5 set ups. There is very heavy brush and steep hills as an alternative route. If I can make the mudflat route work I think it will be a time saver.
From your description of the mud it sounds as though "load spreading" would do the trick.?ÿ I've made up a triangular frame of 4"x2" with triangular ply gussets at each corner, each drilled with a 0.5" hole. Placed on the soft mud the frame creates enough extra bearing surface to spread the load of the level; legs each go into one of the holes in the ply. As the frame isn't solid right across you can put one foot inside it if necessary in order to observe.
Try it out and see how it goes.
It sounds like you've found a fairly solid path through the flat and I don't have any magical mud setup. However, I offer that if you can find any constantly moving water through the flat at low tide (i.e. a 'creek'), that should provide your firmest footing and prevent loss of any boots. Around here, one good step outside of the creek and you'll probably be looking for new footwear.
Brainstorming as I type: Use an aluminum tripod without the legs extended (i.e. a low setup), carry some 4x4 (3x3) squares of plywood (heavy, I know) and toss them on the mud for a setup. You can't stand on them, only the tripod/ level. they should prove stable for a decent duration. I've used the same to work on docks from the plough mud, below. The dispersion of weight leads to a surprisingly stable work surface... you might lose the plywood.
@chris-mills Thinking the same way. Good one. The 2x4 triangles will definitely save weight and probably make pulling the setup base off the mud a lot easier.
When the lake levels around me are down in the winter time, I've done similar in some of the muddy areas for a total station set-up.?ÿ Of course the depth probably wasn't quite as much.?ÿ I was able to get by with some 2X2 stock from the big box store which I cut into 24" stakes.?ÿ Just have to drive them in enough that the tops are very rigid.
It worked well for me - provided a way to see more boundary markers from one set-up and cut down on total set-ups in the traverse.?ÿ I would say there was time and effort savings in my case that made it worthwhile to do.
When traversing across swamps that aren't frozen I'd often cut spruce poles 4-6" diameter and drive them in until firm to set a point and keep the tripod stable. Typically there would be a mat of vegetation a couple feet thick and water underneath and it was remarkably similar to walking on a water bed. Mudflats on the other hand are a different matter. They can be stable to walk on and then suddenly they're not and quick sand has nothing on it. The vacuum around your legs as you sink makes self rescue near impossible and people around here have died after getting stuck and drowned when the tide came in. If it's tidal, I'd exercise the most extreme caution working around mudflats.
Thanks everybody for the great ideas. We probably won't be doing the project until next Spring but I'll be sure to report the results.
