Application of thermal mixing on sewer pipe inspection in high flows

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Ongoing changes in land use and climate have shown that conventional wastewater systems will receive additional loading due to increased peak runoff and flooding events. In addition, the majority of wastewater systems were built during a rapid growth period and now require a continuous condition assessment. Sanitary sewer systems are a significant portion of a municipality's capital investment budget and annual operating budget. The City of Thunder Bay is responsible for conducting condition assessment of around 500 km of a sewer pipeline network. Conventional condition assessment methods like implementing closed circuit television (CCTV) are very labor intensive and expensive. The City of Thunder Bay is investing in practical research projects to find easily updated and cost-effective monitoring systems to acquire information about the quality and ageing of wastewater collection systems. The present proposal aims to conduct laboratory experiments to perform sensitivity analysis of thermography and using thermal sensors for condition assessment of wastewater collection systems using wireless technology. Thermal mapping techniques are proposed using both conventional temperature sensors and emerging thermal imaging cameras. In this project, a novel, self-contained wireless data collection system will be developed to dramatically reduce the costs of pipe assessment. Using a winter season model, where the average temperature of wastewater is around 25 degrees and underground water is approximately 3 degrees, data collection units can directly measure water temperature using a sensitive thermometer, and can record thermal images using sensitive infrared cameras to identify the position and magnitude of flow infiltration. The monitoring data from the operational units in the field testing will be validated with the thermal mixing theory. The outcome of this research project will offer the City of Thunder Bay and other municipalities in Canada a validated, integrated tether-less unit that can efficiently monitor the existing condition of pipelines in underground sewer systems.