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CANADIAN MUNICIPALITY WATER MAIN CONDITION ASSESSMENT AND PIPE RENEWAL METHODS
- Author / Creator
- Wu, Yi Chen
In general, there are two types of pipe renewal methods, replacement and rehabilitation. Replacement methods is where pipes are replaced with new ones using original open-cut methods, or trenchless technologies such as pipe bursting and auger boring; while rehabilitation methods repair pipes by installing smaller pipes or liners inside the old pipe using technologies such as CIPP, spray-on lining, slip lining, etc. The market for rehabilitation of water infrastructure has been growing rapidly due to the increasing volume of aging underground utilities in urban centres. The implementation of trenchless rehabilitation method for underground pipe renewal can improve construction efficiency and significantly decrease project costs compared to open cut methods. Trenchless technologies provide a much faster repair time, and consequently reduces the crew size and cost in built-up city areas where open-cut methods are more difficult to perform (Hashemi et al., 2011).
In order to understand the challenge with rehabilitation of water mains, comprehensive understanding of existing water main in terms of overall system condition, degree of deterioration of different pipe material, and characteristics of water mains will need to be performed. With this information, the rehabilitation method conducted on the water mains can then be further improved through better planning and more effective product for different water main pipe materials or circumstances. To gather the information, an online survey questionnaire was conducted to collect data on municipal water main conditions as well as methods used for pipe renewal. First of all, information on pipe diameter, buried depth, as well as lengths are gathered with respect to pipe diameters distinguishing between transmission and distribution. Furthermore, information related to service connection, including the years that certain materials were used, and methods for establishing connections to water mains were collected. Meanwhile, another important aspect addressed in the survey is the pipe failure rating/factor for different materials. This information allows water providers and those involved in water main rehabilitation to understand the performance of various materials within the system and plan appropriate mitigations. Lastly, the condition assessment methods employed by the surveyed water utility providers are summarized. Also, replacement and rehabilitation methods used previously for system pipe renewal are examined and compared.
CIPP can provide structural support to both internal and external loads, while spray-on techniques provide chemical resistance as well as adding minor strength to the existing pipe, but theoretically will not be able to withstand surrounding structural loads. Current existing CIPP liner products for pressurized water pipes are designed and installed using the same standards as for gravity mains with low internal pressure consideration. The full review of the current gravity main product and installation standard are presented in the body of this thesis. The current methods have been safely applied in the industry following the water rehabilitation manual M28 (AWWA), as well as adapting knowledge and experience from past projects. However, the development of standards specifically for application of CIPP to rehabilitate pressurized water mains is very important as pressurized water mains will experience high internal pressure with pressure surge occurring throughout the system, such that the current design standard are not sufficiently developed for their application on pressurized water mains.
Furthermore, there is a high potential for expanding the industry by increasing the knowledge about the equipment and skill set for this type of water main rehabilitation. The current major market for CIPP products and the history of the development of trenchless rehabilitation technology are discussed, as well as current methodologies. Furthermore, the design, installation, and monitoring of current water main rehabilitation products are discussed, where the associated risks or limitations are described. Also, outline of existing standard tests for main rehabilitation are included as part of the evaluation of existing products and procedures, improvements and future research topics are also suggested.
- Graduation date
- Spring 2020
- Type of Item
- Master of Science
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