Minnesota Administrative Rules

4715.1120 OIL AND FLAMMABLE LIQUIDS SEPARATOR.

Enclosed garages of over 1,000 square feet or housing more than four motor vehicles, repair garages, gasoline stations with grease racks, work or wash racks, auto washes, and all buildings where oily and/or flammable liquid wastes are produced shall have a separator installed into which all oil, grease, and sand bearing and/or flammable wastes shall be discharged before emptying into the building drainage system or other point of disposal, when floor drains or trench drains are provided. The separator shall be located inside the building.

Exception: Private garages classified as Group U occupancies serving one- and two-family dwellings.

Each separator shall be of watertight construction and of not less than 35 cubic feet holding capacity, be provided with a water seal of not less than three inches on the inlet and not less than 18 inches on the outlet. The minimum depth below the invert of the discharge drain shall be three feet. The minimum size of the discharge drain shall be four inches. The separator may be constructed either: (i) of monolithic poured reinforced concrete with a minimum floor and wall thickness of six inches, (ii) of iron or steel of a minimum thickness of 3/16 inch, protected with an approved corrosion resistant coating on both the inside and the outside, or (iii) of fiberglass resins that comply with ASTM C-581 and meets IAPMO Material and Property Standard, PS 80-2003b, for clarifiers.

The separator must be provided with a nonperforated iron or steel cover and ring of not less than 24 inches in diameter, and the air space in the top of the tank must have a three-inch vent pipe, constructed of approved metallic material, extending separately to a point at least 12 inches above the roof of the building. Drains and piping from motor vehicle areas must be a minimum of three inches in size. Drains discharging to an interceptor must not be trapped and must be constructed so as not to retain liquids. In motor vehicle wash facilities, a sand interceptor which meets the requirements of part 4715.1130, subpart 1, except that no water seal is permitted, may be installed to receive wastes before discharging into a flammable waste separator.

No cleanout, mechanical joint, or backwater valve shall be installed inside the separator which could provide a bypass of the trap seal. Only wastes that require separation shall discharge into the separator, except that a water supplied and trapped sink may be connected to the vent of the separator. Whenever the outlet branch drain serving a separator is more than 25 feet from a vented drain, such branch drain shall be provided with a two inch vent pipe. A backwater valve shall be installed in the outlet branch drain whenever in the judgment of the administrative authority backflow from the building drain could occur.

A separator must be installed to be readily accessible for service and maintenance, and must be maintained by periodic removal of accumulated liquids and solids from the separator.

Statutory Authority:

MS s 16B.59; 16B.61; 16B.62; 16B.64; 326.37 to 326.45; 326B.101; 326B.106; 326B.121; 326B.13; 326B.43 to 326B.49

History:

9 SR 1557; 19 SR 590; 28 SR 146; L 2007 c 140 art 4 s 61; art 6 s 15; art 13 s 4; 33 SR 2042

Published Electronically:

May 14, 2012