Geo-Foundations spent the fall and winter of 2009-2010 in Estevan, Saskatchewan working around the clock to construct rock anchors for a spillway remediation project at Sask Power's Boundary Dam. With a limited window available for the demolition and reconstruction of the entire spillway slab prior to the arrival of the next spring frechette, stopping the rock anchor work to avoid the bitter prairie winter weather was not an option. Project challenges included working on a pronounced slope under a temporary enclosure (once winter arrived), sequencing multiple post-tensionings of the same anchors, and completing the work within a necessarily aggressive schedule. A total of 421 rock anchors were installed using double-head duplex drilling, embedded in mudstone and post-grouted twice each. With some rock anchors having to be post-tensioned as many as 5 times in order to sequentially and progressively compress the subgrade beneath the new spillway slab, more than 2,000 separate post-tensionings were performed.
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