Minnesota Administrative Rules
Agency 167 - Pollution Control Agency
Chapter 7080 - INDIVIDUAL SUBSURFACE SEWAGE TREATMENT SYSTEMS
Part 7080.1960 - SEPTIC TANK BAFFLES
Current through Register Vol. 49, No. 13, September 23, 2024
All septic tanks must be baffled according to items A to G. Effluent screens are allowed to be substituted for outlet baffles.
A. Baffles must be installed at each inlet and outlet of septic tanks. Outlet baffles are required on compartment walls if the transfer hole is at the liquid level.
B. Baffles must be resistant to corrosion or decay. Inlet baffles must not restrict the movement of solids.
C. Baffles must be integrally cast with the tank or affixed at the top and bottom with connectors that are not subject to corrosion or decay. Baffles for fiberglass-reinforced polyester tanks are allowed to be either resin bonded or secured with suitable structural adhesive. Sanitary tees used as baffles must be affixed to the inlet or outlet pipes with a permanent waterproof adhesive.
D. The inlet baffle must extend at least six inches, but not more than 20 percent of the total liquid depth, below the liquid surface. The inlet baffle must extend above the liquid surface in compliance with part 7080.1920, item E, and at least one inch above the crown of the inlet sewer.
E. The outlet baffle and any baffles between compartments must extend below the liquid surface a distance equal to 40 percent of the liquid depth, except that the penetration of the indicated baffles or sanitary tees for horizontal cylindrical tanks must be 35 percent of the total liquid depth. They must also extend above the liquid surface as determined in part 7080.1920, item E.
F. There must be at least one inch between the underside of the top of the tank and the highest point of the inlet and outlet baffles.
G. The nearest point on the inlet baffles other than sanitary tees must be no less than six inches and no more than 12 inches from the end of the inlet pipe. The nearest point on the outlet baffle, other than sanitary tees, must not be closer than six inches and no more than 12 inches from the beginning of the outlet pipe to the baffle. Sanitary tees used as inlet or outlet baffles must be at least four inches in diameter.
Statutory Authority: MS s 115.03; 115.55
