Section 123-5-004 - Force Mains004.01 Force mains will be sized so that a cleaning velocity of at least 2.0 feet per second is achieved at the minimum pumping rate of the lift station.004.02 The minimum diameter of force mains transporting raw domestic wastewater will be four inches.004.03 Force mains will be designed with air relief valves located at high points in the force main. Vacuum relief valves may be required where an evaluation of the design indicates they are needed.004.04 Force mains discharging into manholes will enter the manhole no more than two feet above the gravity flow line.004.05 Force mains and all installed valves and appurtenances will be designed to withstand the pumping shutoff head pressure. Force mains will be pressure tested equal to water mains.004.06 Force mains will maintain the same separation distances to water mains and wells required for gravity sewers. See Chapter 5, 002.08 - 002.10.004.07 Wastewater pumps will be selected that operate effectively over the range of head loss conditions that will exist over the life of the system. Piping system head capacity curves will be prepared for both the new pipe condition using the appropriate coefficient of roughness and for the aged pipe condition that will result after years of service. For the aged condition, a Hazen Williams "C" value not higher than 120 will be used for polyvinyl chloride (PVC), polyethylene or lined ductile iron, and for unlined iron or steel pipe a "C" value no higher than 100 will be used.123 Neb. Admin. Code, ch. 5, § 004
Amended effective 9/4/2019