I remember Neillsville from "The Rock" radio station. ;)
So, to answer the question, we need to know where the water is coming from. You mention that it's due to a high water table.
As such, I'd not ever finish the basement. It will always be one power outage or one clogged drain away from being ruined again.
It also means that your dehumidifier will never 'win'. Basements are moist by default simply due to cooler temps, but if you have constant hydrostatic pressure, it will always be an uphill battle.
Your (what I call) interior footer drain will certainly help, but you're at the mercy of the drains always remaining unclogged and the sump pump always having power. You'll also have to make sure it can handle excessive rain during those big midwestern downpours.
If it was merely an occasional rain/snow melt issue, I'd feel OK finishing the basement, but given the high water table, I'd consider rethinking doing a full finish project down there.
If your water problems are primarily at the footer, It may be OK. As that is exactly what the drain system is designed to handle. But if you have actual cracks in the walls and water is coming in there, I'd be definitely be hesitant.
One other note...a bit further west into MN, the clay soil we were on had a lot of radon. So you may want to get a radon test before thinking of finishing the space as well.
Oh, one last comment: note that the systems being proposed are in no way 'waterproofing' systems. They are water abatement systems--in that they are designed specifically to not be waterproof and actually allow the water to come in so it can be moved out. It's a nit-pick, for sure, but actual waterproofing is an entirely different discussion.
First, the square footage of the house doesn't mean a thing in this case. The important factors are water pressure and supply line size and the height of the fixtures above the pressure tank and the pressure tank size. The well pump fills the tank, then the air bladder applies pressure to the water in the tank. a check valve stops water from going back towards the well. When you call for water, the internal tank pressure pushes it through the pipes.
A few different problems may exist here that would cause your problem.
The tank pressure membrane may be waterlogged. It will still show static pressure, but drops to a very low PSI when a faucet is turned on. Often, you will hear the pump cycle more that usual in this situation or you may see the water pulsate instead of a steady flow. What is your static vs open line pressure?
Another common problem is the backflow check valve is leaking. This causes water to be pushed back towards the well. the tank pressure will slowly decrease between pump runs.
If this problem has been long standing, then the pipe size going to the second level may be too small. Second floor fixtures or ones a longer distance away should be fed with at least 3/4 inch line, not 1/2 inch line.
The last factor may be that the well is not delivering enough gallons per minute. If the pump has to run for excessive time to fill the pressure tank, this could be the problem.
I'm sure there may be a few other items to check, but these are the most common problems.
Best Answer
What diameter?
From here it looks like a vent for a drywell or French drain. If it's about 4" (10cm) diameter, that'd add to my suspicion.