I'm about to begin a basement bath project in Wisconsin. Small bath - WC, shower, lav plus a wash sink in the utility room. Septic system with tank entrances 4' above floor so a small pit is required.
psuedo 3D drainage layout:
I would like to sanity check my assumptions for venting and cleanouts. I'm under the impression I do not need a dedicated CO for the WC or shower - WC is 3" at 24' with 90deg of horiz changes - Shower is 2" at 6' with 45deg change into the wye, and carries another 20' through 3" with 90deg direction changes. Based on this, I believe I can satisfy CO requirements via removing the WC and the shower floor drain (solvent weld P-trap)... am I correct?
For venting, am I ok using the vent from the lav to cover the shower and WC? It's about 10-12' from each DU before the wye connecting the lav.
Finally, I have a question about cleanout clearances. I know I need 18" clearance for the existing CO leading to the tank. How is that clearance defined? I want to locate my pit as close as possible to the outside wall, but I'm unsure if I'll be violating the clearance requirement.
Is it a radius (green) or is it a straight planar distance (blue)??