Industry recommendations for hydroelectric tunnel inspections

Numerous hydro plants include headrace tunnels that were constructed many years ago, and in some cases, have been operating beyond their originally envisaged design life. Unlike powerhouses and intake structures that are readily accessible for inspection and maintenance, hydropower tunnels have limited access and can require a near-total outage of operations for inspection and maintenance. Hydroelectric tunnels are increasingly being inspected with limited outages using remote-operated vehicles harnessing significant advances in technology to provide high resolution photographs, videos, and sonar imagery that can be interpreted as part of a structural condition assessment.