WA – Samson Brook Remedial Works Stage II Completion
Author: Bob Wark.
The main contract for the Stage 2 of the Samson Brook Dam Remedial works was completed at the end of January 2014. The 2012 ANCOLD Tour of the South West visited the site before the start of the works which then carried through on schedule to May 2013 when an unusually wet May curtailed the completion of the works with less than a couple of meters of the embankment left to complete.
The original dam was a pug core dam with supporting shoulders of earth and rockfill, but lacking adequate filters. The foundation cutoff consisted of a concrete core wall that had been very well constructed to depths of over 20 m. The Stage 1 works involved sleeving the twin outlet pipes.
The Stage 2 works were undertaken by Watpac under a contract with the Water Corporation and included excavation of the downstream shoulder of the embankment, reconstruction of the downstream shoulder of the dam with embankment and foundation filters and included a small raise of the embankment to facilitate the optimal upgrade of the spillway capacity in the stage III works.
The works required the reservoir to be emptied during the Stage 1 and 2 works. An operating restriction remains in place limiting the filling of the storage to FSL – 6 m until the stage III works are completed. These are not expected to be undertaken until the end of the decade.