Design

(a) Compartments. A septic tank may consist of one (1) or two (2) compartments. All septic tanks shall have a removable lid or a manhole opening of at least twenty inches (20") in diameter or, if rectangular, having no side less than twenty inches (20") in length over each compartment. All lids and manholes shall be sealed to prevent leakage. (b) Two-compartment tanks. The passage in the common wall of two-compartment tanks shall be located below the liquid level and between twenty percent (20%) to forty percent (40%) of the liquid depth. There shall be a vent through the common wall. (c) Inlets and outlets. The outlet of the septic tank shall be two inches (2") lower than the inlet of the septic tank. Baffles for inlets and outlets shall be constructed and located as follows: (1) Construction. Baffles shall be used on all inlet and outlet lines. Cleanout openings shall be located directly above the inlet and outlet baffles. Inlets and outlets shall have a watertight seal. The inlet cleanout shall have an opening of sufficient size to allow for maintenance that extends a minimum of two inches (2") above ground elevation. The cover for the opening shall have a lock, locking bolt or some type of tamper-resistant fastener, or require a tool for removal. (2) Location. All baffles shall extend to within two inches (2") of the top of the septic tank. (A) Inlet. Inlet baffles shall extend at least six inches (6") below the liquid depth of the septic tank. (B) Outlet. Outlet baffles shall extend below the liquid level by twenty percent (20%) to forty percent (40%) of the liquid depth. (d) Precast concrete tanks. Precast concrete tanks shall have a minimum: (1) wall thickness of two and one-half inches (2-1/2"); (2) bottom thickness of three inches (3"); and (3) cover thickness of three and one-half inches (3-1/2"). (e) Poured-in-place concrete tanks. Poured-in-place concrete tanks shall have a minimum: (1) wall thickness of six inches (6"); (2) bottom thickness of three inches (3"); and (3) cover thickness of four inches (4"). SUBCHAPTER 9. PUMP TANKS