Water Online

May 2017

Water Innovations gives Water and Wastewater Engineers and end-users a venue to find project solutions and source valuable product information. We aim to educate the engineering and operations community on important issues and trends.

Issue link: https://wateronline.epubxp.com/i/816402

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Page 16 of 38

and valid alternative selection. By quantifying the likelihood of failure (in time) and reducing all the consequences of failure, as well as the potential alternatives down to triple bottom-line costs (in dollars), much of the subjectivity of other alternative analysis methods is avoided. While the Taggart Outfall 30 project team moves forward into design, the Portland Bureau of Environmental Services is continuing to refine and improve their powerful NBCR asset management tool. Tiers In Bellingham For drinking water assets, the City of Bellingham, WA, is another example of a city taking proactive steps to address its aging water system. Constructed in 1939, the city's five-mile buried water supply system, which consists of a 66" wood stave intake pipe, a 78" hand-dug tunnel, and 48"/68" concrete cylinder supply pipelines, was constructed to take raw water from Lake Whatcom and convey it to the city's 24-MGD Whatcom Falls Water Treatment Plant. For the eight decades it has been in use, the system has reliably served the city. In an effort to extend the system's useful life, the City of Bellingham engaged CH2M to perform a condition assessment of the intake system between Lake Whatcom and the treatment plant. Undertaking this thorough condition assessment was an important component of the city's approach to characterize its assets, identify the key repairs needed, and prioritize the repairs with the available budget and resources. A tiered approach with three levels of assessment was utilized for the condition assessment. • Tier 1 assessment represents the first-level, least-invasive, and least-costly methods of inspection, such as non- destructive and visual testing. • Tier 2 efforts would be warranted if issues or concerns are discovered during the Tier 1 assessment. Tier 2 activities primarily include methods such as excavation of test pits and collection of pipe materials or samples. Entry into the interior of the pipe could be considered a Tier 2 activity if access is readily available or reasonably feasible without major modification. • Tier 3 activities, if warranted, could be considered upon completion of Tier 2 activities and evaluation of those results. Tier 3 activities involve deploying instruments within the pipe and/or removing the asset from service and conducting a manned entry examination of the interior of the asset. Tier 3 activities are typically the most costly to implement of the three tiers of assessment activities. Applying the same approach to each of the city's buried water assets, the tiered approach provided a cost-effective way to assess the condition of the whole intake system within the budget constraints of the city and provided meaningful data on what steps the city must take to keep its water infrastructure functioning properly. While Bellingham's existing intake system remains useful and in relatively good condition, preserving the long-term usable condition of this system and others like it will require regular monitoring, inspection, analysis, improvements, and target replacement of key elements. To stay ahead of the problems associated with deteriorating aging infrastructure, condition assessment and rehabilitation is a critical component of a pipeline asset management program. As these case studies demonstrate, it is equally as important to select a "right-size" condition assessment strategy to identify the most cost-effective method. Thoughtful implementation of such a program is necessary to avoid overspending on inspection and overanalyzing the system beyond what is necessary to provide our cities with a high level of service, while managing acceptable risks and minimizing costs to ratepayers. n 14 wateronline.com n Water Innovations PIPELINEMAINTENANCE Daniel Buonadonna joined CH2M in 2008 and currently serves as the Global Practice Lead for CH2M's Condition Assessment and Rehabilitation Services (CARS) team. Daniel is dedicated to helping communities face the challenges associated with aging infrastruc- ture and asset management. About The Authors City of Bellingham water supply facilities Tammy Cleys is a supervising engineer for the City of Portland, Bureau of Environmental Services and has been the project man- ager for several large-diameter conveyance projects ranging from new tunnel construction to trenchless rehabilitation.

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