OK- moving forward- I got the sump pit dug out as deep as I can get it (about 18")- The new plastic basin is 24"- I will most likely cut the bottom off the basin and lay it in a bed of gravel and then a patio block. Do i still need to put filter fabric to prevent silt? (there was not one there b4)- The soil is very rocky/slate (I live in central NJ). Also the new bin is not perforated so is there a formula for how many holes? The old metal pit seems to have a number of 1/4" holes in it (problem is-half of that old one disintegrated so I can't really tell)- thanks!
I never would have cut out the bottom, now there will be no strength to stop the side load.
I drill 3/8 holes all over the outside and the bottom wrap screen cloth around the outside to stop the silt from coming in and just set the pump in the pit.