Is it possible for a sump pump pail to be too deep?
NOTE: While I agree that NORMALLY the depth of the sump pit itself is not a factor it IS a part of the "lift" for the pump.  This specific question is about an unusually deep sump pit.  So it would be foolish to just say, "it doesn't matter how deep the pit is" because it DOES matter, in this case at least!

Yes, there is a limit on how high a particular sump pump can raise the water up a pipe.  It's called the "head" and the problem is that the closer you get to the head limit, the lower the pumping capacity of the pump is.

Here is a link to the Wayne company site, which is a major pump maker:

Wayne Pumps Data

If you have the manual for your pump (probably too much to ask for) you will probably find the spec in there.  If you know its make/model, it could probably be looked up.

But the key thing is that the TOTAL height from the bottom of the sump pit to the highest point in the outlet pipe must be less than the head specification.  Most home-use sump pumps have a head of at least 10'.