Gas pockets in a wastewater rising main: a case study.
This paper presents a case study of an existing wastewater rising main (WWRM) in which an extreme transient event produced by simultaneous power failure of the pumps caused the rupture of a 1.2 m (48 in) prestressed concrete cylinder pipe (PCCP), causing an important leakage of sewage. The event and the methodology followed in order to validate the diagnostics of the failure are described. The detail study included in situ observation of the system, experimental investigation in a setup, hydraulic analysis, as well as details of the structural strength of the WWRM. After the extensive investigation and several simulations of fluid transients for different scenarios and flow conditions, it was found that stationary small gas pockets accumulated at high points of the WWRM were identified as the principal contributory factor of the failure. This case study serves as clear warning of the consequences of operating a WWRM with gas pockets at its high points.
Establishment of a large-diameter pipeline failure risk matrix in water distribution systems in Taiwan

 The bursting of large-diameter water pipelines in distribution systems will lead to industrial, economic, and public safety impacts. Therefore, multi-criteria analysis (MCA) was applied in this study, which utilizes a series of quantifiable parameters to establish the mathematical method of a risk model. The risk matrix of a pipeline was defined as the multiple of the probability of pipeline failure and potential consequences of pipeline failure. By combining the GIS (geographic information system), each evaluation unit was assigned to different risk levels. The large-diameter (above 800 mm) pipeline length statistic for various risk evaluation units of Taiwan Water Corporation reveals the length of high risk is 171 km (7.7%), secondary high risk 574.6 km (25.8%), middle risk 714.3 km (32%), low risk 701.5 km (31.5%), and the unranked length is 67.8 km (3.0%). Finally, the detection frequencies were classified as high risk with a term check of every five years, sub-high risk with planned check every five to ten years, medium risk with checking/monitoring if needed, and low risk with quick repair and no need to take measurements and monitoring. Therefore, we can significantly lower the probability of bursting for large-diameter pipelines in the water distribution system.
Manual for designers of spring-supplied gravity-driven-drinking water rural delivery systems
AGUA PARA LA VIDA is a non-profit organization with branches in the USA and in France and whose purpose is to help remote rural communities acquire enough safe drinking water. Our members are active in Nicaragua where we have designed and helped build drinking water supply systems since 1987. We expect to participate in answering this primary need in other countries as well. specializing in the mechanics of liquids and gases for thirty two years. His first drinking water project dates back to 1962. The material for this manual was gathered in the field in Nicaragua and in the Laboratory in Berkeley. Dan Mote, then Chairman of the Mechanical Engineering Department supported the work. Several classes of Engineering Seniors chose this very topic for their senior laboratory class and contributed useful data. The author is grateful to them all.