Abandonment of Low-Level Outlet Conduits…Think it Through Before you Grout it Through

Deterioration of low-level outlet conduits is a common problem, especially for older embankment dams. When the existing conduit deteriorates to a point where it can no longer serve its intended design purpose, a decision must be made to rehabilitate, remove and replace, or abandon it.

Removal and replacement is the most reliable approach, but will most likely require draining of the reservoir and result in the highest cost to the owner. Rehabilitation can be a reasonable alternative and is typically accomplished by one of two methods, sliplining or cured-in-place pipe (CIPP) liners; however, it may not be applicable for severely deteriorated conduits (See Figure 1) or changes in loading conditions.