safe depth to drain vinyl pool w/vinyl stairs

[cheshamjim]

Scotsdale, you are absolutely correct about needing a tarp large enough to not only accomodate your pool's length and width, but the depth as well. We are unlikely to find a tarp that big at the local Lowe's or Home Depot.

I think the word "tarp" might be a little misleading for our purposes. I think plastic sheeting better describes what we are talking about to accomplish this job. I Googled the term and found this. This is expensive material in the sizes we need ($130 for a 32' x 100' roll), but I think I'll go for it next spring.

The way I visualize this working is this. My pool is 16' wide x 32' long x 6' at the deepest location (we don't dive ). I figure the 32' wide roll would be adequate for me cut to a length of 44' (the roll is 100' long).

I'll spread the plastic film over the pool and maybe temporarily put weights on the corners to keep the breezes from blowing the sheet off. Then I'll add water on top of the sheet which will keep the new water separated from the old. I'll add enough new water starting out to get the sheeting to sink down and against the old water and the exposed pool walls. Then I'll start pumping the old water out. Most sump pumps will pump water faster than new water can be added, so I'll pump and stop, fill and stop, pump and stop, etc...pumping and filling need not be done simultaneously and in perfect synchronization.

The sheeting I have referenced is only 4 mils thick (.004") but the sheet really shouldn't be stressed since it will essentially be in equilibrium. I think it will work fine.

While I've never done this, I'm confident that by draining slowly and observing whether, in fact, the sheet is being forced effectively against the pool walls, I can control things. If things start to go south, I can abort the process. I'd be out the cost of the sheet and the rental for a submersible sump pump , but I think its worth the risk to get my CYA right.

I sure would be thankful if anyone who sees some problem with this plan would speak up.

-Jim