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Have a 20′ x 10′ auxilliary parking slab, used only when visitors fill the main parking area by the house (maybe 4 times a year). Off the one side is a 45 degree downhill. Been there for a year and a half. After pouring the driveway the other week we have new water runoff patterns which currently channel _some_ water off the side of this aux parking area. 3 1/2″ in 2 days highlighted the problem of neighbor not having adequate measure for diverting water at this point, and his new runoff and my new runoff have magically funneled over the side and caused a 5′ section of the bank to drop off right around the middle where the control joint is. I can reach about 6″ under the slab where the dirt has collapsed away.
The question is, how is this best fixed? I know I have to divert the water, but I don’t know what will properly support the undercut slab so that my truck doesn’t someday break the edge off and pitch me down the hill. Ideas? Thanks.
Jim
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Hello Jim
Step 1 - Don't park the truck there.
Step 2 - Define new water channel, maybe with added curb on slab to divert to your runoff pattern.
Step 3 - Pack in some new fill or grout it and maybe bulwark the slope to keep the rest of the bank from dropping away. Good opportunity for a neat terraced look. Whatcha think? Got enough water running to catch a good ride downhill in a washtub??
*Thanks. Think packing and tamping fill (sideways no less) can ever get tight enough to support the concrete, or will there inevitably be a gap between the base and the slab that can never be as solid as the original? Whether a 1/4" or 4" gap, unsupported concrete is still unsupported and can break off. Or not? Never had quite this situation before.Won't bother with too much pretty dressing up of the dropoff be/t it goes right into thick woods with lots of poke weed, poison ivy, and stickers. The runoff has enough force to easily move 3/4 stone, but not river rock or rip-rap. Sure did a good job of soaking and dropping a well-seeded bank.
*How about pumping in some concrete after you fill and tamp the hollow.
*Deal with the water runoff problem first. Deal with it well. When you are sure it is done right, then go for the fix on the underfill. In the meantime, don't park on the slab.To fix under the slab when ready... Remove enough material to be sure you have gotten all the loose stuff. Side and bottom should be solid. This won't be easy, or quick. When side and bottom of area is solid, mix up some cement. extra thick. Not dry, but close to it. Pack some in there and beat it back into the hole with an old 4x4. Keep packing until it is all full. Trowel finish, and let cure.
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Have a 20' x 10' auxilliary parking slab, used only when visitors fill the main parking area by the house (maybe 4 times a year). Off the one side is a 45 degree downhill. Been there for a year and a half. After pouring the driveway the other week we have new water runoff patterns which currently channel _some_ water off the side of this aux parking area. 3 1/2" in 2 days highlighted the problem of neighbor not having adequate measure for diverting water at this point, and his new runoff and my new runoff have magically funneled over the side and caused a 5' section of the bank to drop off right around the middle where the control joint is. I can reach about 6" under the slab where the dirt has collapsed away.
The question is, how is this best fixed? I know I have to divert the water, but I don't know what will properly support the undercut slab so that my truck doesn't someday break the edge off and pitch me down the hill. Ideas? Thanks.
Jim