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Potable water treatment is one of the most challenging and complex systems that municipalities need to deal with considering limited resources. A study from mid-90s showed that the continuously deteriorating Canadian water supply system would require $3.1 billion to bring the system at satisfactory level. Drinking water treatment plants (WTP) include several components, such as tanks, basin, and pumps. Operators are able to spend a small portion of the available resources or their plant’s infrastructure and equipment compared to water quality and day-to-day operational activities. The research presented in this technical paper aims at developing condition assessment model(s) for the WTP components. Essential condition parameters of WTP include technical, physical, environmental, and operational aspects. To determine the condition index of a WTP component, value additive multi-attribute theory has been used where average weights and scores are considered for the model parameters. Data on WTP conditions are collected from experts and consultants across Canada and the United States. It is concluded from the model results that the average condition index for settling basins, ranges from 9.6 (best scenarios) to 1.9 (worst scenarios) and from 9.6 to 3.4 for pumps. Analysis reveals that, for tank and basins, design and construction parameter is the most important parameter for WTP condition, while the operational parameter is the most important one for pumps. The developed models are expected to benefit academics and practitioners (municipal engineers, consultants, and contractors) to prioritize inspection and rehabilitation planning for existing water treatment plants. [ABSTRACT FROM AUTHOR]

An outbreak of cryptosporidiosis occurred in the town of North Battleford, Saskatchewan, Canada in the spring of 2001. The outbreak left thousands of people sick including about 50 people hospitalized. The source of the outbreak was from the city’s surface water treatment plant. The Sedimentation Contact Unit did not satisfactorily remove suspended solids from the source water, resulting in filter breakthrough. Contaminated water was released into the distribution system causing the outbreak. Communication breakdown and confusion exacerbated the situation, extending the duration of the outbreak. The outbreak prompted the province to change the way it regulated municipal utilities of water and wastewater. [ABSTRACT FROM AUTHOR]

Exponent Failure Analysis Associates was retained by a municipal government to perform an independent study of a fatal collapse in a local sewer treatment plant. The reinforced concrete dome shell covering a cylindrical prestressed concrete digester tank collapsed due to sludge overfilling. The collapsed dome, similar to domes on two adjacent identical tanks, showed radial and circumferential cracking prior to the collapse. Analysis showed the dome cracks were a result of temperature and shrinkage stresses, and of internal overpressure happening at some time prior to the overpressure resulting in the collapse. Inspections of the postfailure debris and analysis of the dome cracking preceding the collapse show practically no relationship between the dome condition prior to collapse and the failure. Failure of the sludge level monitoring system and the lack of a sludge overflow system are cited as the primary reasons for the failure. [ABSTRACT FROM AUTHOR]