Technical Manual: Conduits through Embankment Dams (FEMA 484)

Conduits through Embankment Dams9.8 Instrumentation and monitoringInstrumentation and monitoring are performed for three distinct reasons:1. To aid in the evaluation of water pressure conditions surrounding a conduit anddetect signs of a problem (i.e., first identification). Key detection elementsinclude:a. Visual monitoring for unusual settlements or deformations above theconduitb. Visual monitoring for seepage emerging in or near the downstream end ofthe conduitc. Inspection of the interior of the conduitd. Structural measurement points in the conduit (where possible)e. Embankment measurement points in the vicinity of the conduit alignment2. To gain a better understanding of an already detected problem for use inevaluation and design of a remediation3. To monitor embankment and foundation water pressures during and followingconduit remediationInstrumentation in a conduit or embankment dam furnishes data to determine if thestructure is functioning as intended and to provide a continuing surveillance of thestructure to warn of developments that could endanger the safety of theembankment dam facility. Conduits are not normally instrumented unless there is aspecific concern due to known adverse foundation conditions or other unusualcircumstances. The means and methods available to monitor an emergency event orcondition that could lead to a embankment dam failure include a wide spectrum ofinstruments and procedures from very simple to very complex. The need forinstrumentation designed for monitoring potential and/or existing deficiencies atexisting embankment dams must take into account the threat to human life andproperty downstream of the dam. Thus, the extent and nature of theinstrumentation depends not only on the complexity of the conduit andembankment dam, and the extent of the deficiency being monitored and the size ofthe reservoir, but also on the potential for loss of life and property damagedownstream of the dam (FEMA, 1987, p. 51; Reclamation, 1987b, pp. 1-3).234