with wide slots between them constructed in two profiles, those associated with the penstocks had an additional section containing intakes and screens as well as a downstream slope to support the penstock while the other profile had a flatter slope and were only wide enough at the top to house the road across the top of the dam. In conjunction with the block sizes, different concrete mixes and the passing of cold water through cooling coils were used to maintain the block temperature at 10˚C (50˚F) and thus cracking of the concrete. Cracking can allow water into the body of the dam which can lead to allow uplift and instability during earthquakes. Once the blocks had reached its final stable temperature the slots were filled with concrete. Once the concrete in a block was stable the coils were filled with grout. A deep low pressure consolidation grout curtain was installed on the upstream side of the dame and extending into both abutments to improve the strength of the rock under the dam and prevent leaks. Drainage holes were constructed just downstream of the grout curtain as well as under the power house with 40 pressure gauges installed to record the up pressure on the structure. A total of of concrete were used in the construction of the dam and spillway consuming . Cement was mostly sourced from the Milburn Lime and Cement Company's factory at Burnside (near Dunedin) or via ship into Port Chalmers. A major expansion was undertaken by Milburn in order to supply the cement. Aggregate was obtained from the Clutha River at Commissioner's Flat, while water came from the river. Fletcher Holdings subsidiary, Stevenson & Cook manufactured and installed the penstocks, the steel frame of the powerhouse and the spillway gate winches The rolled plates for the penstocks were transported by truck from their factory in Port Chalmers to site where a workforce of 80 men fabricated the plates using automatic submerged arc welders into sections in a purpose built workshop and then installed them in position. All welds were X-rayed during fabrication and radiographed after installation as well as pressure tested except for the concrete encased section at the intake. Stevenson & Cook lost money on the penstock contract, which contributed to the company being wound up in 1959. Fletcher Construction undertook the work to clad and roof the power house. Supply and installation of the