. Unfortunately, the tank had not
been pumped in maybe 10+ yrs of usage.

The inspection company claims the field is "saturated" when
a probe hole is dug.

After 10+ years of no pumping, there is an excellent chance sludge has
found it's way into the leach field and clogged the pores in the field
floor and walls. Hence the high water level.

Since your field surface area does not appear to be soggy and smelly,
reverting to a three year pumpout cycle may allow the field to
recover. But but it would take a long time for the bacteria to get
the job done.

If your field was squishy and smelly, there would no hope of recovery
unless it was left unused for a couple years.

In order to sell the house, you could add a couple of infiltrators to
the field. This would add about 18' of unused length of the field and
allow the leachate level to drop to normal (and improve the field's
chances of recovery). With the liquid level reduction, you would then
pass inspection.

Infiltrators are orderable from building supply centers. They are
easy to install because they require no gravel - just digging a
trench, placing the infiltrators, then covering them. The small
amount of dirt they would displace could be distributed around the
yard.

Using bacterial agents can be tricky. Most are advertised to reduce
the need for pumping. This is accomplished by liquifying the sluge in
the tank and sending it to the field. The sludge then helps clog your
field's arteries - but you don't have to pump as often!

My above comments are based on experience and research only. I'm not
a professional in these matters.

Gary