During the construction of the DC Water Clean River (DCCR) First Street Tunnel Project in Washington DC, three water mains heaved due to the soil freezing operations associated to the construction of the tunnel shafts. As the water mains would continue to be impacted by the construction project, DC Water identified the need to monitor the mains for development of leaks during the remainder of the tunnel shaft construction. DC Water’s Water Program Management evaluated, piloted and installed three continuous leak detection technologies along the 1988 48-inch ductile iron, 1922 30-inch cast iron, and 1893 6-inch cast iron water mains impacted by the Tunnel Project. Typical acoustic leak detection surveys were not considered practical for this application as construction of the tunnel shafts would continue for another 6 months, and the movement of the ground due to the soil defrosting was not expected to settle for at least 1 year after DCCR tunnel construction operations were completed. Therefore, several fixed leak detection technologies that provide continuous monitoring, autonomous correlation, and automatic alerts were evaluated and installed along these mains. The presentation will include: A summary of the technologies evaluated; Procurement, installation, and construction costs associated to the pilot of three different leak detection monitoring units; Lessons gained during the evaluation phase and technology implementation process, including: setup of the units, communication hardware, and web user interface and software requirements.
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