Welcome to TFP. I have a few ideas that might gve you an avenue toward making your decision
I have an inground vinyl pool in Michigan that was constructed by the original owners in a storm water catch basin on the side of a hill with a terrace, so I can tell you exactly what was done to control water table issues
In my case, they did the following:
1. Constructed a drainage ditch around the entire perimeter of the pool, connected it to two drains that run down the hill on either side of our house, and covered the surrounding drain with large decorative stone (eg smooth like river rock) -- this is on he outside of the paved area.
2. Dug a sump under the diving well and plumbed it to the pool system so that by closing the valves on the main drain and skimmer, you can pump off collected water to waste.
The advantage to the second construction feature is that unlike the more common systems where a pool builder will create a sump/well with a pump in place at the side of an excavation, the pump never burns out and is then inaccessible without costly reconstruction. Others create the monitoring well with access to drain, but you don't get the power or convenience of having this plumbed right to the system.
I have lived here 5 years now, and have not had any floating liner issues whatsoever, even with the spring floods of the heavy snow two years ago that flooded our neighbors entirely. (We live on a river that reached 100 year flood level...but I should not we're up hill.)
In fact, my liner is 15 years old. The previous owners had two chocholate labs that clearly swam in the pool (scratches on vinyl) and this liner still does not leak
One less-than-conventional thing we do in relation to water table is that we do not drain dwn for winter. We instead rely entirely on doing a good job of blowing out the lines, capping returns with duck plugs, and using a gizmo in the skimmer. The techs from the company that built the pool recommended this method of closing to maintain full pressure against the liner for spring.
I do have a friend in a high water table who did not have these construction features and whose liner floats every single season in spring. While that has been tough on his liner in terms of a snug fit, he has still been able to enjoy his pool for about 20 years now...the liner more or less reseats itself when the water table recedes a little. He has gone through two or three liners now though.
In his case, in mine and likely yours, I would be more concerned with a fiberglass pool in this kind of setting. My reasoning is that if the pressure were great enough to pop the shell, the expense to solve would be extraordinary. Vinyl seems to me a little more forgiving, with slightly more give for the walls, etc. I might be all wet on that
I also feel that vinyl is a little more forgiving if its good, thick (eg the 28 mil not 20) and well-installed, so with the dogs in mind, if you go that route, go with a thicker, premium lining.
Many people love their fiberglass pools but for me, I would also worry about ground shift and the freeze-thaw cycle causing stress cracks. On one hand, fiberglass is incredibly strong and will last forever...but to my mind, I'd want something a little more flexible/forgiving in that a vinyl liner can be easily repaired or replaced. While the fiberglass is more expensive on the front end, with liner changes, the cost is likely similar over the life of the pool.
My wariness of fiberglass in high water table/shifting ground may be misguided -- I don't have any concrete data to back it up save he occasional picture of a popped pool
So take that with a grain of salt.
But in your shoes, I might hire an unbiased hydrogeologist to assess your land, water table, give advice, review bids and oversee the construction plans. I had the good fortune of hiring one very familiar with our area to assess the drainage of the property and the viability of the pool versus future pool problems when I purchased this house as a foreclosure, because the unusual features could have made it a nightmare.
Instead, while complicated, the engineering has turned out to be relatively sound, as he predicted
