Accumulation and Mobilization of Material Near Pipe Appurtenances in a Full-Scale Laboratory

Abstract

This paper investigates the occurrence of enhanced material accumulation near pipe appurtenances in drinking water distribution systems and how pipe flushing strategies can have an impact on the mobilization of this material. The accumulation of sediments in fittings and appurtenances of different materials and ages is a well-known cause of water quality problems and a long-standing preoccupation of water utilities. A set of four experiments was completed in a full-scale laboratory pipe rig using iron oxide particles to simulate material dynamics in the system. Results showed that wye fittings located at the ends of the pipe loop favored the accumulation of particles, and changing flushing direction enhanced their mobilization. These results reinforce the findings of previous studies that suggested that common appurtenances in drinking water networks can favor material accumulation and provoke water quality issues. Foreknowledge of these hotspots and their sediments behavior upon mobilization during flushing might assist water utilities in improving flushing strategies. It is recommended that reverse flushing can be used to address high material accumulation near pipe appurtenances, especially in topologically simple areas of a network where flow paths are predictable and easily ascertained.