Here the raised form of the reservoirs becomes more obvious, however they are also dug into the surface, with the floor of the reservoir being approximately as far below grade as the rim is above. In this method of construction, the excavated material is used in the bunds. The design drawings do show the bunds to have an impervious clay core but to what extent that was carried out cannot be seen. The small corrugated iron shed on the East rim covers the deep concrete shaft that housed the outlet valves. The shafts that hold the valves to control flushing and run off are housed at grade level near the berm. The concrete structure is an access pit to inspect the overflow culvert which runs some 400 metres below ground in 450mm earthenware pipes to a diversion and grate structure (picture VVVV) at ground level near a small creek which obviously took flushing and overflow flows.
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Photo taken in Centennial Park, Otipua Creek 7974, New Zealand
Misplaced? Suggest new location