Trust me I have done alot of that bullsh!t!!

You need a pump set up to pump clean water and hooked into a half inch steel pipe.  If you can do it from the top make the pipe long enough to do it all from the top and reach the bottom.  If not you got to get in the tank so make the pipe about 3 feet tall and put a tee on it with a 6 inch nipple on each side, cap one end and put a quick coupler and the hose out the other.  This is your "water drill".  Looks like a T with one hand on each side of top of tee and the bottom doing the drilling.    Did I mention I have done this before?

pump fresh water in the new made water drill and start drilling holes all over in the salt. 

once that is started you need a sump pump pumping the crap out into another tank that you can spread of haul to a sprayer.  You need both pumps going at the same time.

Once you get going if things are working good the salt will just "melt" under your feet.  With enough fresh water and time you can get them clean.  may take 500 gallons or may take 2000 gals of clean water.  With the amount you got, I would say no more than 2000 gals.  And I have done like 100 time the amount you got.

Use a fan to put fresh air in the tank if you go in.  I have been cert. in confined space, have air meters, etc.   Don't get yourself killed over the deal.

No, I will not come and help you.