Grouting Rehabs Earth Dam

Baker, Wallace H.; Gazaway, Herff N.; Kautzmann, Gary; ,

Grouting Rehabs Earth Dam

by Wallace H. Baker, (F.ASCE), Pres.; GKN Hayward Baker Co., Odenton, Md. 21113,
Herff N. Gazaway, Proj. Mgr.; GKN Hayward Baker Co., Odenton, Md. 21113,
Gary Kautzmann, Proj. Engr.; Power Plant Addition Section, Pennsylvania Power & Light Co., Allentown, Pa. 18101,

Serial Information: Civil Engineering—ASCE, 1984, Vol. 54, Issue 9, Pg. 49-52

Document Type: Feature article

Abstract:

To accommodate increased storage needs the Pennsylvania Power & Light Company had to reactivate a fly ash basin and raise an adjacent embankment dam. However, seepage through the original embankment and its underlying rock had to be eliminated without damaging the dam. Rehabilitating the earthfill dam required a carefully designed and monitored grouting program. The 1982 dam rehab program was designed to focus on and distinguish between portions of the dam and varying geologic conditions to determine grouting needs. Crucial steps in the rehab program involved (1) detailed subsurface investigation; (2) cased-hole drilling to protect the embankment materials from hydraulic fracturing; (3) low pressure, short duration water testing to assist in type selection of the grout; (4) field selection of grout types, on a hole by hole basis; (5) high speed shear mixing of low water:cement or water:solids ratio grouts to produce a stable grout mix; (6) continuous mixing injection of controlled gel time; (7) injection under low pressures of selected grout type in splitspaced borehole pattern and secondary holes and tertiary holes in high take areas; (8) careful monitoring of injection pressures and flow rates to detect embankment fracturing; and (9) piezometer monitoring of before and after grouting water levels within the dame embankment and foundation.

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