Lessons from the Failure of Two Reclaimed Water Lines in California

摘要

The Landfill Reclaimed Water Distribution System consists of two pump stations andrntwo force mains. Pump Station No. 1 pumps into a 640 m (2100 ft) long 90 cm (36rnin) diameter Force Main under a static head of 150 m (500 feet). Pump Station No. 2rnpumps into a 1125 m (3700 ft) long 75 cm (30 in) diameter Force Main under a staticrnhead of 90 m (300 ft). Both pipes are Ductile Iron Pipes with TR Flex joints,rnwrapped in polyethylene sheets and were supplied by U.S. Pipe. The lines wererntested under a static pressure of 2000 kPa (300 psi) after completion. Subsequentlyrnthe pipelines were connected to the discharge headers and tested under a staticrnpressure of 2000 kPa (300 psi), at which time significant movements were observedrnat the pump station piping at both Pump Station No. 1 and Pump Station No. 2. Thernauthors were engaged by the Sanitation District to investigate movements observedrnon the pipe headers at both Pump Stations during the pressure tests. Thisrninvestigation focused on the adequacy of the design of the entire system, and therninstallation procedures during construction of the project. The manufacturer'srnrecommended installation procedures are also reviewed. This paper reports on therndetails of this investigation and how appropriate corrective actions were taken to stoprnfurther movements in the lines once the pipelines were put back into service.