questions about repairing vermiculite base in older in-ground pool

howdy from Indiana
I am hoping to get some pointers and info about restoring my older in-ground pool.
I am starting with a new liner that will be here in a week or so.
Before installing the liner I am hoping I can help the bottom (patching and smoothing) without adding too much matieral that it causes my measurments to change.
I guess question one is, what would be the least amount I can use to skim coat? (I am going to try DIY vemiculite patching).
question two is what do I do about the spots that are allowing the ground water the leak in while I repair those areas?
I need to patch but ground water is comming in 100% of the time in a couple places and that leads into the question of does the surface need to be dry or does it matter?
I am also wondering if I can cut out a large hump that wasnt addressed on the original install (hack job)
...can I cut it out and patch over?

I am sure there are some other things I need to know before I jump into doing this but I have to do something soon. I dont think the current condition of the base is acceptable and I know I can make it much better.
I will snap some pictures and load on here, showing the hump and some of the 'bad spots'.

...looking forward to all the advice and info I can get to keep me outta trouble!

Hi, Glove, and welcome to the Pool Forum! I'm going to ask one of our Pool Forum Support Team members (Waste aka Ted) who is a pool installer to take a look at your thread. Be patient. He's a busy guy .........

so I picked up some portland type I / II and some vermiculite.
I am not sure the vermiculite is the correct type. It is 'hortacultural' grade.
From what I have read I use these in a 2:1 ratio, 2 parts crete to 1 part vermiculite.
Please let me know if this vermiculite is the type I want to use.

My liner arrived yesterday so I am hoping I can use this weekend to get the bottom smoothed out and be ready to drop the liner monday.

Welcome to The Forum!

Sorry I might not have gotten to you in time.

What I use for patching is a 2:1 verm to crete by volume (it probably works out the same).

As long as the vermiculite doesn't have chunks, larger than ~ 1/16", it's fine.

You have a ground water issue that needs be dealt with, any water flow will wash the Portland out of the mix and leave you with mush. If you have a 'well point', hook a pump up to that and keep the bottom dry. If you don't, dig a hole in the bottom of the deep end ~ 10", put ~4" of gravel in it and install a sump pump, then fill the hole with gravel around the pump, the top of the pump ought be just above the floor)

Make your repairs and keep the pump running until you are ready to drop the liner. Sweep the floor at least 2X after the patches have set!!!!!!

(The info becomes a little technical from here - I don't want to waste my time, if you've already dropped the liner - I'll be sure to check in tomorrow to see if you need the rest)

Well, I have not dropped the liner yet. It was supposed to be today, but I pushed it back till tomorrow. The water delivery guy wants 2 days notice.
I have managed to mix up some verm and crete to patch some parts. It has worked pretty well in the places that are not letting ground water in.
The hole scares me, Waste. The ground water isnt comming in very fast and I would like to keep it that way.

There are a couple errands I need to get knocked out this morning. When I get home I will snap some pictures to refer to with questions.

Glove

OK, let me give this to you straight, no platitudes nor attitudes.

You certainly have a 'ground water' issue, it's the ebb and flow of that water that caused your need to repair the bottom. Over the years the water flowing through the vercon base has eroded the crete out of it and will do the same in minutes on a fresh mix, as opposed to the years it took to wash out the set floor.

I had hoped your installer had put in a well point you could tap onto to keep the water at bay while you repaired the floor and dropped the new liner, but apparently not. :mad:

What I think will serve you best is excavating the hole I mentioned and installing the sump pump. With seeping ground water, if it's only at the floor of the hopper, you could probably get away with a ~ 6" deep hole and 2" of gravel under the sump pump.

You are worried about digging a hole in the bottom of a pool that has already washed out. If you don't, the patches you make will wash out before the new liner is set. :(

With the sump pump, you can keep the water at bay while you patch all the washouts, let them set and do the sweeping. Then you drop the liner in the shallow end and run it out to the deep end (**** if you pull the liner over the pump - put a piece of cardboard over the top of the pump, it gets HOT and can burn a hole in your liner!!!!!) When the water is imminent, pull the pump, fill the hole with gravel to ~ 1" below grade and patch it with hydrolic cement [* there are a few tips and tricks for this that I'll share, if you need me to].

Do you have a main drain? If so, there are other things you'll need to do when you start filling the pool, like installing and cutting it out.

It seems to me, and I may well be wrong, that you're planning a pool party for the 4th. In the long run, you'll be better off properly repairing the pool and dropping the liner, as well as coming up with a permanent solution to the ground water issue.

Just my $.02:cool:

didnt get a chance for pictures, again.

No, no party planned for the 4th but I have "a guy" that seems to be pretty good at liner replacements. Today was the first free day he had and then we decided to push it to tomorrow (tues) because the water delivery guy wanted a little more notice.
so, this morning, the guy drops by to have a look see before starting.
he liked the patchwork .

I asked about the deep end and he tells me we can make the bottom of the hopper 'better' with just sand and to not sweat it. true?

I also noticed he ordered the liner at 42" in the shallow but at the wall I am seeing a short 43 and as you get away from the wall the floor dips down to 45 in the deepest dip.
When I asked if we needed to raise the floor (not only to make it flat) but to get a lil closer to the 42" he said the liner will stretch and that where the floors meet the walls is the most critical point to measure.

...is this thing really gonna stretch that much without blowing out?

...back to my patchwork.
I have applied a very VERY thin layer in the places I used the mix. it was rock hard this morning, after about 12 or so hours. I filled and flattened a few more places today and I hope it is as firm tomorrow in the AM.

As of now, the pool guy will be here in the morning so we can tape cracks and seams on the walls and set the liner sometime before noon when the water starts comming.
shoulda started this project of reapiring the base weeks ago.

==========================================

oh, I do have a main drain. As for a well point, I dunno. I noticed a plug off to one side of the bottom in the main drain housing in addition to the hole that assume is the suction line to the pump.

maybe I should be pulling water outta the hole the plug is in?

Waste, if its at all possible for you to call or text, I would love to pick your brain over the phone.

seven 6 five - two two 8 - fifty fifty, I will be up early (4 am indiana)

oh, I do have a main drain. As for a well point, I dunno. I noticed a plug off to one side of the bottom in the main drain housing in addition to the hole that assume is the suction line to the pump.

maybe I should be pulling water outta the hole the plug is in?
Waste, if its at all possible for you to call or text, I would love to pick your brain over the phone.

seven 6 five - two two 8 - fifty fifty, I will be up early (4 am indiana)