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25 involved with the abandonment of an outlet works conduit. Figure 6. Abandonment of a conduit by pumping cement grout through holes drilled from the surface of the embankment dam to depths of up to 60 feet. [1] Figure 7. Grout being delivered to the pumping truck. [1] Summary Abandonment of low-level outlet conduits may be an option if the following apply to your dam:  The results of an inspection of a low-level outlet conduit reveal damage that could lead to a future “incident,” repair or replacement alternatives are prohibitive, and abandonment methods cannot cause harm.  There are no regulations or requirements for regular water flow or release. Regular control of the reservoir level is not considered a critical feature in the performance of the dam. If the above two conditions apply then the following also needs to be considered to adequately manage risk for water conveyance in an unusual or emergency event:  Are there alternate means for water conveyance during flood or emergency events? If the dam is on a live stream, this is a must!  If the dam is off-channel: o Is it feasible to install a new permanent siphon or high-level outlet? o Is it feasible to quickly install pumps and/or temporary siphon to handle water conveyance requirements? o Can inflows be controlled? Low-level outlet abandonment is usually not a viable option for larger or high hazard dams. The owners and operators should fully understand the implications of loss of use of the low-level outlet. Alternative methods of water conveyance should be provided as described in this document prior to abandonment of the existing outlet. Abandonment of a low-level outlet is typically done by fully filling the conduit with grout or concrete and should be conducted in accordance with best practices as outlined in Chapter 14 of the FEMA Technical Manual, Conduits through Embankment Dams. The designer should consider replacement, rehabilitation, and abandonment alternatives carefully and understand that each project site may have specific challenges that need to be considered. Useful References [1] FEMA (2005), Technical Manual: Conduits through Embankment Dams, FEMA 484, Federal Emergency Management Agency, September 2005. [2] FEMA (2005), Technical Manual: Plastic Pipe Used in Embankment Dams, FEMA 508, Federal Emergency Management Agency, September 2007. [3] AECOM (2013a), “Low-Level Conduits – Rehab or Replace?” Western Dam Engineering Tech Notes, Vol.1 Issue 1, March 2013. FEMA’s technical manuals provide detailed discussion of parameters that should be considered during the conduit abandonment design process. They also contain detailed discussion on repair and replacement of conduits. FEMA - Conduits through Embankment Dams FEMA - Plastic Pipe Used in Embankment Dams