Originally Posted by Glenn
Hi again,
Because of the height of the water table, my new septic tank will be very shallow. The top will be at about ground level, and the entry to the tank will be 7 inches below grade. I'm worried about running a drain to it at the right pitch.
The house is on a slab, with the existing septic tank under the slab. I'm going to have a plumber dig a trench in the slab from the 3" soil stack that gathers the 2nd, 3rd and 4th floors, under the wall of the house, and trench out to the tank. He'll run a 4" pipe from the 3" soil stack to the septic tank. At 1/8" per foot drop, I'll be able to go about 40', assuming I start 2" below the slab to replace the concrete. So that takes care of the top floors.
On the 1st floor, the new 4" drain pipe will go right past (within 2 feet of) the existing toilet and shower. Since the existing toilet drain is in the slab and (I'm guessing) enters the existing septic tank too low to use for the new septic tank, I'll try to connect the toilet into the new drain line as it goes by.
Glenn