Wastewater siphons represent some of the most difficult municipal assets to assess due to complex hydraulics, limited access, and operational constraints that restrict traditional inspection methods. This presentation examines the application of free-swimming multi-sensor inspection technology (INGU Pipers®) as a rapid screening tool for evaluating the condition and performance of large, multi-barrel wastewater siphons, using the City of Lethbridge triple barrel siphon as a detailed case study. The Lethbridge system consists of multiple asbestos cement barrels operating under gravity-driven and pressurized conditions. Screening was conducted to establish a baseline understanding of system integrity, identify hydraulic inefficiencies, and inform future maintenance and high-resolution condition assessment planning. The inspection collected hydraulic grade line data, acoustic leak detection, air pocket identification, and indicators of internal restrictions while the system remained fully operational. Results confirmed no active leaks within tool sensitivity, while identifying localized air accumulation and segments exhibiting elevated hydraulic losses consistent with internal deposition and reduced conveyance efficiency. Screening data supported targeted recommendations including progressive pigging to restore hydraulic performance and follow-up structural assessment to better understand long-term asset integrity. This case study demonstrates how minimally invasive screening enables utilities to evaluate complex siphon infrastructure quickly, reduce uncertainty, and make defensible decisions regarding maintenance and capital planning. Attendees will gain practical insight into deployment strategies, data interpretation, and how screening technologies can support phased, risk-based condition assessment programs for critical wastewater siphons.
