609.2 Trenches.

Water pipes shall not be run or laid in the same trench as building sewer or drainage piping con structed of clay or materials that are not approved for use within a building unless both of the following conditions are met: (1) The bottom of the water pipe shall be not less than 12

inches (305 mm) above the top of the sewer or drain line. (2) The water pipe shall be placed on a solid shelf excavated

at one side of the common trench with a clear horizontal distance of not less than 12 inches (305 mm) from the sewer or drain line.

Water pipes crossing sewer or drainage piping constructed of clay or materials that are not approved for use within a building shall be laid not less than 12 inches (305 mm) above the sewer or drain pipe.