Since the 1960's there have been a succession of reports of leakage of water from the downstream face of Heapey embankment, close to the eastern shoulder. In November 1997, during the refilling of the reservoir after a dry summer, the issue of water was sufficiently large to require an emergency draw-down of the reservoir. The draw-down procedure has been described by Page (2002). A ground investigation into the structure of the embankment and surrounding strata was undertaken and was followed by a phased grouting operation to control the leakage. On raising the reservoir level after the first phase grouting operation the leak continued in its original location. A second phase of grouting was undertaken during November and December 1999 which was successful.
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