Buoyant Interceptor Inspection Featured in Trenchless North America

The first known buoyant gravity sewer in the world, the Lake Oswego Interceptor Sewer (LOIS) underwent a condition assessment after a decade of service. Because this innovative infrastructure is fully submerged beneath Oswego Lake, access points for a standard inspection were limited. To avoid draining the lake or disrupting service, the tailored approach combined trenchless inspection technologies, engineer-diver-led exterior assessments, and carefully coordinated barge and caisson access operations on the lake. The critical data gathered from the assessment informed a five-part capital improvement plan to guide future maintenance.

Brendan O’Sullivan and Brandon Falk, trenchless technology leaders at Consor, and Stefan Broadus at the City of Lake Oswego coauthored a white paper that was published in full by  North American Society for Trenchless Technology (NASTT) on page 58 of the 2026 No-Dig Show Conference Edition of Trenchless North America.

Read the full white paper: Inspection of the LOIS Buoyant Interceptor.