Esorfranki Geotechnical is poised to complete a curtain grouting subcontract awarded by Norland Construction at the Cengane Dam in the Eastern Cape.

The construction of a new dam wall is planned as part of the OR Tambo District Municipality’s Upper Culunca regional water supply scheme. This leading geotechnical services company has provided about 600 m2 of dry curtain grouting under pressure to fill any cavities before Norland Construction begins work on the dam wall.

This leading geotechnical services company has provided about 600 m2 of dry curtain grouting under pressure to fill any cavities before Norland Construction begins work on the dam wall.

Grout curtains are used under dams where the foundation would otherwise pass too much seepage, or create dam instability. A grout curtain usually consists of a row of vertically drilled holes filled with pressurised grout. The holes are drilled at intervals and in such a way that they cross each other, creating a curtain. Grout is injected into these holes with grouting jets, which use a high-pressure fluid stream to erode a cavity.

“This is the first job of its kind that we’ve undertaken for some time and we regard it as a step in the right direction as part of our strategic plan to re-enter the grouting market,” says Anton Naude, director at Esorfranki. “Past contracts include curtain grouting of an earth wall at Sun City and at Lydenburg Dam.”

Before the Esorfranki team could begin work at the Cengane Dam site, they had to blast a number of large boulders using a “boulder buster” to create a workable surface. The primary holes were introduced at 3-m intervals, with secondary holes at 1.5-m intervals and tertiary holes at 7.5-m intervals.
Naude says no major leaks were identified and only minor grouting was required.