7.4.6.3.Sumps or Tanks (See Note A-7.4.6.3.)

(1) Only piping that is too low to drain into a building sewer by gravity shall be drained to a sump or receiving tank. (2) Where the sump or tank receives sanitary sewage, it shall be water- and air-tight and shall be vented. (3) Where the sump or tank receives subsurface water from a subsoil drainage pipe, it shall be provided with a water- and air-tight cover. (4) Equipment such as a pump or ejector that can lift the contents of the sump or tank and discharge it into the sanitary building drain or sanitary building sewer shall be installed. (5) Where the equipment does not operate automatically, the capacity of the sump shall be sufficient to hold at least a 24 hour accumulation of liquid. (6) Where there is a building trap, the discharge pipe from the equipment shall be connected to the sanitary building drain downstream of the trap. (7) The discharge pipe from every pumped sump shall be equipped with a union, a backwater valve and a shut-off valve installed in that sequence in the direction of discharge. (8) The discharge piping from a pump or ejector shall be sized for optimum flow velocities at pump design conditions. (9) The discharge pipe from every pumped storm sewage sump shall be equipped with (a) a union and a check valve installed in that sequence in the direction of discharge and pumped to above grade level, or (b) a union, a check valve and a shut-off valve installed in that sequence in the direction of discharge.