newbie w/ ejector pump questions

My wife and I just bought our first home and I am already thinking of making changes. The first is adding a bathroom in the finished basement. The problem is that I will need to install an ejector pump and I am totally stumped on how to do this properly. my biggest concern is that the water table is really high over here and I know I WILL hit water once I break through the concrete floor for the hole for the pump. What happens in a situation like this? How do you go about installing the pump if the hole will always have water in it? Also, how far down do I need to dig to get this thing in there? I want to do as much of the remodeling work as possible and I have 100% confidence in myself that I can do it, I just need some advice on this pump thing. the pump will be handling a half bath that gets little use, the sink in that bath, a washine machine, and a sink for a bar.

Hydrostatic water can be a problem. A lot depends on how fast the hole fills in with water.

You will need to dig the hole big enough for the plastic pit to fit into it.

Why do you say you know you will have water coming in?

One of the first pits I ever installed went smooth as glass. Got it cemented in and planned to install the pump the next day.
When I walked in the next morning it was floating on top of a hole filled with water.

I mention water because everytime I dig in the backyard. I hit water about a 12-18" down. The water table in my yard is high. I have a drain in my driveway and in the march is actually fills up rather then draining once all the ground thaws out. The water is just bad here. I just dont want to have the pump running all the time as it trys to eject water out of the basin. I have never seen an ejector pump so I have no idea how is is made. Assuming I can get a nice clean dry hole dug, will the pump setup be sealed where no outside water can enter the tank? I think the best time to dig the hole will be in August when the water is at its lowest level.

If I knew my basement was sitting in water-saturated earth, I would not want to disturb the floor at all. There are systems available that have holding tanks and ejector pumps that sit on top of the floor, and I would likely use something like that instead. In any case, a typical ejector pump is about the size of a 2-gallon pail or larger, and it would sit down inside a pit about the size of a 30-gallon trash can.

I'm with leejosepho, With water 18" below the yards surface I would think twice about doing that.

You could start a problem that you only wish would happen to your worst enemy.

I would start by installing outside passive drains to take the ground water away from the house then see if you need a pump.