Obtain a Sludge Judge and ...

Obtain a Sludge Judge and reach down into the layer about a inch or two above the "Sludge storage layer" ( and usually about 2 feet about the solid bottom) and get a sample of this level and send it to a lab to get the assay of the sludge plus the total solids.  This will tell you approximately how much liquid you will have to get out of the sludge.  There are a few minerals like Silica or a polymer that will imporve the drainage with out having to squeeze out   as much water.  A big savings in costly electrical power.