(A) Horizontal separation of water mains from gravity sewers.
(1) Water mains shall be separated from gravity sewer mains by a horizontal distance of at least ten feet unless:
(a) The bottom of the water main is at least 18 inches above the top of the sewers; and
(b) The water main is placed in a separate trench or in the same trench on a bench of undisturbed earth at a minimum horizontal separation of three feet from the sewer.
(2) When it is impossible to obtain the required horizontal clearance of three feet and vertical separation of 18 inches between water mains and sewers, the sewer must be replaced with water main materials meeting both a minimum pressure rating of 150 psi and the requirements of § 3.02 of this chapter. However, a linear separation of at least two feet shall be provided.
(B) Separation of water mains from sewer force mains. Water mains shall be separated from sewer force mains by a horizontal distance of at least ten feet unless:
(1) The force main is constructed of ductile iron material meeting a minimum pressure rating of 150 psi and the requirements of § 3.02 of this chapter; and
(2) The water main is laid at least four linear feet from the sewer force main.
(C) Separation of water main and sewer crossovers.
(1) Vertical separation of water mains crossing over any sanitary or storm sewer should be at least 18 inches when measured from the bottom of the water main to the top of the sewer. If physical conditions prohibit this separation, the water main shall not be placed closer than six inches above a sewer or 18 inches below a sewer. The separation distance shall be the maximum feasible in all cases.
(2) Where the water main crosses under a storm or sanitary sewer or over said sewer with less than 18 inches of separation, both the sewer and water pipe shall be situated such that the joints of both pipes are as far as possible from each other. The water main shall have nitrile gaskets. In the case of storm sewer, the pipe shall be reinforced concrete with flexible O-ring gasket joints. In the case of sanitary sewer, the pipe shall be of water main quality material for a minimum of 20 feet in accordance with SUDAS.
(D) Separation from sewer manholes. No water pipe shall pass through or come in contact with any part of a sewer manhole. A minimum horizontal separation of three feet shall be maintained.
(E) Exceptions. Should physical conditions exist such that exceptions to divisions (A), (B), (C) and (D) above are necessary, the design engineer must detail how the water main and sewer installation are to be engineered to provide equal protection.
(F) Water crossings.
(1) Surface water crossings. The pipe for above water crossings shall be adequately supported and anchored, protected from damage and freezing and accessible for repair or replacement.
(2) Underwater crossings. Water mains entering or crossing streams which drain areas greater than two square miles in urban areas and 100 square miles in rural areas shall be of ductile iron pipe with flexible watertight joints or shall be installed in a steel casing pipe and installed as follows.
(a) The top of the water main shall be below the natural bottom of the stream bed at least one foot when located in rock, three feet when located in other material or at a greater depth when crossing major streams. The trench shall be backfilled with crushed rock or gravel.
(b) The water main shall be securely anchored to prevent movement of the pipe and provided with easily accessible shutoff valves located outside of the floodway at each end of the water crossing.
(c) 1. The stream bank shall be seeded, sodded or otherwise protected from erosion upon completion of the project.
2. Water mains entering or crossing streams which drain areas less than two square miles in urban areas and 100 square miles in rural areas should be of ductile iron pipe with flexible watertight joints or installed in a steel casing pipe. Drainageway crossings in areas where no evidence of erosion exists are excluded from these requirements.