The Argument for Mandatory Outlet/Drain Inspections on a 5-year Cycle.

ABSTRACT ONLY - Montana currently requires dam owners to have the outlets/drains on their dams inspected every 5 years, congruent with their 5-year dam evaluations (permit renewal).The reason for outlet/drain inspections every 5-years? While this high frequency has been questioned, there is an alarming statistic that of the 36 structures inspected since 2020, almost 40% (14) were found to be deficient. Deficiencies found include inoperable gates, deterioration of CMP, worrisome cracks in concrete, and concerning pipe deflection.One concern is that five years ago many of these structures looked okay. This is not just small dams with CMP, we are seeing a trend in larger dams too.In this presentation, I will present a clear argument for conduit inspections on at least a 5-year cycle and present multiple case studies to illustrate this position.