The augmentation and safety upgrade of the Chaffey Dam project required the raising of the Morning Glory Spillway by 6.5m for the augmentation, raising the existing dam embankment and crest by 8.1m, re-using the existing pre-cast concrete parapet units for the safety upgrade and replacing the existing bridge at Bowling Alley Point with a new bridge and associated roadworks above the new full supply level so they would not be inundated.  The raising of the dam embankment and crest and raising the Morning Glory Spillway (MGS) required 180,000 tonnes of crushed and screened quarry product. The material was crushed and screened from stockpiled rock on the dam site from the original dam construction and hauled from the bottom of the dam wall to the top of the dam crest and to the area around the MGS on the upstream side of the dam wall. To facilitate the movement of this material, two haul roads were constructed to the right- and left-hand sides of the crest of the dam wall.  For work on the MGS, a crane pad was established adjacent to the MGS. This pad was suitable for the 160-tonne Liebherr track crane and was positioned within the working radius required for the heaviest anticipated lift. To minimise the volume of material pushed into the water for the crane pad, a 6m-high temporary dump wall was constructed on fill already placed which then formed the crane pad. The reason for minimising the volume of material for the crane pad was to not block the multi-level water take off at the front of the upstream pier of the MGS.   The most technically challenging element of the construction was raising the Morning Glory Spillway. The inside concrete surface of the raised MGS required a Class 1 finish and needed to be constructed to a specific parabolic curve to avoid cavitation of the concrete surface as a result of water flowing down the spillway. Good access to the inside face was crucial so the works could be carried out safely and productively while ensuring the spillway remained operational for water release and spill event management.  The new raised MSG started 5.7m down the inside of the existing MSG and rose 6.5m in height above the existing spillway lip. The method devised and engineered was to insert circular needle beams into aeration ducts (32 no.) located 7.6m below the lip. These needle beams protruded 1.7m from the existing inside face and provided support for a pre-fabricated work platform. The platform consisted of a grid mesh work deck fixed onto the top of a number of steel beams either welded or bolted together. This provided a safe work platform and allowed water to pass through in the event of a spill into the MGS. The work platform then supported the six levels of temporary access platforms and the wet concrete loads of the first two half-pours. The bottom concrete pour was 5.7m below the existing lip and was completed in two halves, 3m high, amounting to 150m3 of concrete for both halves. The six levels of working platforms provided access to all areas of the inside face of the raised MGS, with these access platforms expanding in diameter as they rose in height to match the expanding diameter of the raised MGS.  The raising of the dam wall and crest by adopting an alternate design by John Holland to construct a reinforced earth soil wall negated the need for placement of rock-fill on the downstream face of the dam and therefore did not require a structure to be built over the dam outlet on the downstream side. It also negated the need to place rock-fill on the upstream face except for a 100m-long section, which was required to construct the new road out to the MGS bridge. This alternative design won the tender for John Holland Pty Ltd.  This civil engineering project has been carried out in a very professional manner to exacting high standards that demonstrate the engineering skill and experience of the contractor’s project team to work co-operatively with the client, WaterNSW, to resolve and implement unique solutions to complex construction issues in a safe and successful manner.