CLEARWATER DAM FOUNDATION DRILLING AND GROUTING
SINKHOLE REPAIR

Piedmont, Missouri

The Clearwater Dam developed a 10-foot diameter sinkhole near station 40+00 on the upstream slope soon after a high water event in May, 2002. The scope of this contract was to investigate and remediate the damaged dam section caused by the sinkhole by utilizing drilling and grouting methods.

A double row grout curtain cutoff was designed to extending approximately 200 feet below the working platform consisting of 130 feet of embankment and 70 feet of foundation rock. Sonic drilling and continuous sampling in the embankment and core drilling and sampling was used to identify the extent and nature of the damaged section. A deep solution feature was discovered in the rock foundation and successfully treated using low mobility grout to fill large voids.

The work included: sonic overburden drilling and casing installation through the earthen section of the dam, percussion rock drilling, exploratory core drilling, borehole washing, borehole video imaging, permeability testing, pressure grouting using balanced stable grout mixes and low mobility grouting for treatment of the solution rock features. Grouting materials included: portland cement, bentonite, superplasticizer, welan gum, and low mobility grout.

For this project, IntelliGrout®, a proprietary computer monitoring system was utilized for real time electronic monitoring and recording of the permeability testing and grouting. IntelliGrout®, provides powerful analytical and graphical tools for production grouting analysis. The system is integrated with AutoCAD and provides never before available graphical representations of water testing and grouting data for closure analysis.

Client: US Army Corps of Engineers, Little Rock District

Owner: US Army Corps of Engineers, Little Rock District