(A)   The construction materials for sewer lines shall be cast-iron sewer pipe, copper pipe (DOT), rigid pipe, vitrified clay (bell and spigot) sewer pipe, concrete sewer pipe (bell and spigot) bituminized fiber sewer pipe or PVC pipe.
      (1)   The joints should be water-tight and root-proof and should be capable of maintaining ten pounds per square inch pressure without leakage.
      (2)   Bell and spigot pipe more than 50 feet from a well may be provided with asphaltic or cement joints.
   (B)   Other types of pipe should be provided with the manufacturer’s recommended joints.
      (1)   General. The minimum size for all sewer lines is four inches nominal size. The lines carrying raw sewage (between the building and septic tank) must be constructed with a minimum slope of one-eighth inch per foot (12 inches per 100 feet) of sewer line. Lines carrying partially treated sewage (septic tank to seepage field or filter) may have a minimum slope of six inches per 100 feet. Drain lines carrying the effluent from a filter to its point of discharge may have a minimum slope of three inches per 100 feet.
      (2)   Septic tank capacities. The septic tank shall have a minimum liquid capacity of 750 gallons and shall be sized in accordance with the provisions of the table in § 53.074.
      (3)   Construction of septic tanks.
         (a)   Septic tanks shall be constructed of corrosion-resistant materials and be of permanent construction.
         (b)   The cover of the tank shall be designated for a dead load of not less than 150 pounds per square foot and, if of concrete, shall be reinforced and not less than three inches thick.
      (4)   Multiple compartments. In tanks of more than one compartment, the inlet compartment shall have a capacity of not less than two-thirds of the required minimum capacity as specified in the table in § 53.074.
      (5)   Length. Septic tanks shall be approximately twice as long as they are wide, except that cylindrical tanks are approved.
      (6)   Depth. The minimum allowable liquid depth shall be four feet. The total depth shall be such that 12 inches of air space shall be provided between the bottom of the cover and the invert of the outlet pipe.
      (7)   Manholes. The inlet compartment shall be provided with at least one manhole. Other compartments may be provided with a manhole. Manholes shall be at least 20 inches square or 24 inches in diameter and provided with covers which can be sealed water-tight. Where removable slab covers are provided, manholes are not required.
      (8)   Baffles.
         (a)   If inlet and outlet baffles are used, they shall extend the full width of the tank and be located six inches from the end walls.
         (b)   Such baffles shall extend at least ten inches above the flow line, but not closer than one inch to the underside of the cover.
         (c)   Inlet baffles shall extend six inches to 12 inches below the flow line and outlet baffles shall extend 12 inches to 18 inches below the flow line.
         (d)   Baffles should be used for tanks of 1,500 gallons or larger in lieu of turn-down pipe.
      (9)   Pipe inlet and outlet. In lieu of baffles, submerged pipe inlets and outlets may be installed consisting of concrete, vitrified clay or cast-iron sanitary tee’s with a short section of pipe to the required depth as indicated in division (B)(10) below.
      (10)   Invert. The invert of the pipe shall be located at least three inches above the invert of the outlet.
      (11)   Subsurface seepage field.
(1975 Code, § 38.33)