A few years ago, a sewer inspection contractor approached the King County Wastewater Treatment Division in Seattle, Wash., with an offer. The contractor had expanded its capabilities to include sonar inspection in tough situations and wanted to show off its new technology. “They wanted to do a demonstration for us,” recalls Lee Miller, lead facilities inspector for the division, part of the King County Department of Natural Resources and Parks. Officials knew just the place: a century-old siphon. Sonar made the difference. That first inspection uncovered a debris blockage that was the source of the problem in the siphon, and
