Under Pressure - Advancing the Art of Force Main Inspection

摘要

The Hampton Roads Sanitation District (HRSD) serves 1.6 million people in southeastern Virginia. HRSD has 9 major treatment plants, 500 miles of mostly pressure interceptor force mains and 81 pumping stations that provide conveyance and treatment. HRSD’s system has nearly 450 miles of force mains being fed by locality pump stations. These force mains are a variety of materials including concrete, prestressed concrete cylinder pipe, cast iron, ductile iron, PVC and asbestos cement. HRSD prepared and executed an ambitious program to assess the condition of their force mains. This approach used state of the art technology and a phased approach to apply resources efficiently. To date, HRSD has assessed the condition of more than 134,000 linear feet of force main. These pipes are divided into several groups including segments that have a failure in the past 10 years, segments that had a failure between 11 and 20 years in the past and have a high consequence of failure, ferrous pipes downstream of pump stations (where air entrainment may be an issue) and force mains near drinking water reservoirs.