Sink hole, pool not level...

[posguy]

Hi all,

OK, we had a 24' round pool installed spring of '03, installer took from the high side and added to the low side, compacting w/ a bobcat, maybe 16" or so. After the pool was installed, I used those landscaping blocks to create a small retaining wall about 12"-18" high and 20" or so from the pool wall around the area of the pool that was elevated. I the filled the area with the leftover base sand, covered it with landscape fabric, and added about 4" of 1.5" landscape stones.

Last year I noticed the pool was not level, dipping about 1.5" on the side that was built up, but the sand base in the pool was solid. Thats when I found this site and did a ton of research and concluded if it didnt get worse, an 1.5" was ok.

This year the dip is more like 2.5", and there is a sinkhole approx 20" long x 8" x 4"deep in the liner parralel to the pool wall on the side of elevated area. I guess the sand inside the small retaining wall washed away and is begining to wash away at or below the cove area creating that depression.

Now the question:

What should I do?

Will the liner shrink if I do a quick fix by emptying, tossing a bag or two of sand in the depression?

All suggestions welcome. I could post pics if nessesary.

Thanks
Anthony

[duraleigh]

Hi, anthony,

Sand as a base compacts well but it has a problem....it washes out easily. That sure sounds like your issue.

If that's it, I would try hard to redirect the water so the washout wouldn't occur. Screenings (crushed rock) are a little more resistant but any fill will wash if the water flow is fast enough.

Now, the fix.....I'm not sure. I would drain as a last resort. I'm not very familiar with AG pools but I think getting that liner back in place may be a real hassle. I would try everything else I could think of first. Some AG folks will be along soon and probably have experience with this issue. Wait to hear from them before you drain.

[posguy]

Thanks Dave.

I think the washout is from rain, if so would it be wise to replace the stones with a scratch coat of concrete, say 2" or even the large patio pavers 18"x18" to reduce the amount of water that is allowed to flow to the base material. Ive attached some pics.

Anthony

[duraleigh]

Basically, your primary goal, like you suggested, is to divert the water from the base of your pool. Anything you can do to divert, maybe even sloped plastic under the rock, will help the most.

If you can't divert, then look for ways to keep it from penetrating vertically.....whatever you can do to make the water run away from your pool rather than under it is your goal.

I can't see your yard but you may have some runoff that you could divert before it got around your pool.

This is a good "common sense" problem with lots of potential fixes....just need to come up with the right combination of aesthetics and functionality.

[hrsdennis]

As for repairing the pool you will need to drain it. Timing is important. You do not want the empty liner in the direct sun for very long. Plan on taking the last of the water out in the eve or early morning hours. Have the repair made and be refilling when the sun is just starting to go over head.

This would also be an excellant time to relevel the pool.

Best of luck, Dennis

[posguy]

If I drain the pool to say 1', can I leave it that way for a day or two? I mean will the liner be ok? This way I can drain to 1', I can remove all the stones around the outside, add sreenings or qp, compact...then finish draining, only remove the liner from the portion that is depressed,toss a bag of masons sand in, smooth and refill? While Im at it should I attemp to raise the portion of the wall that has gone off level, mabe dig under and jack it up an 1" or so.

Speaking of qp or screenings, I need less than a yard, is that the same stuff they sell at Home Depot by the bag for use under pavers, not the fine one, but they call it Stage 1 I think, its about 3/4" muddy, dirty small stones?

Thanks Again
Anthony

[sevver]

screenings are small chips of limestone, not the 3/4 river rock you are refering to. screenings are nice because they compact nicely, and still allow water to permiate it.

[posguy]

Went to the local stone supplier, they recommended qp as opposed to stone dust (screenings) since I will be compacting about 4" or so.

I'll probably relpace my liner since Im worried about it shrinking. Does anyone have any tips on getting a smooth bottom... Ive seen the tips on styro soles ect but was wondering if I should try to give the sand base a "broom" finish after compacting like they do w/concrete and let the weight of the water do the rest. Ive seen the rounded trowels but am hesitant since I am terrible at drywall compond.

Thanks Again
Anthony

[hrsdennis]

Hi Anthony, I use a push broom to smooth the sand and I then do the entire liner install from outside of the pool. I drape the liner over the pool top rails and let the water take out the wrinkles. The liners turn out perfect and no footprints.

Best of luck, Dennis

[It's an Oasis]

You are going to need an overcast day, a transit or laser level, and one person to help you. Drain her down. Lift your uprights up one at a time and place concrete pavers under them. Basically, re-level your whole pool.

Get about 1 ton of sand and pull your liner back to the skimmer/return side. Re-shape you bottom with the center being 3 inces lower than the outer bowl. Broom smooth. Don't forget to put a cove around the base of the wall. Hang your liner from the outside of the pool reaching in. Hook a shop vac up to the base of the skimmer and start adding water. Take your pool broom and hit it against the liner at the base of the wall to work out the wrinkles. The wrinkes will settle at the margins of the water as it rises. Keep circling the pool working out the wrinkles until the water has reached the base of the wall.

To handle the runoff water that is probably washing out you base you need to install a french drain to divert the flow of water.