DAMS & RESERVOIRS
Constructing a joint-free concrete reservoir Keeping concrete reservoirs watertight requires a new approach to design and build methodologies, a prime example being eThekwini Water & Sanitation’s Emoyeni project in Hillcrest. Kendall Slater, principal civil engineer at Knight Piésold (KP), presents the case for a new benchmark in reservoir design and construction. By Alastair Currie
D
ivided into two phases, the completed 25 Mℓ Emoyeni reser voir will be located on the site of an existing potable water storage facility that was demolished in Phase II to make way for the second of two new compartments. The old reservoir had a traditional circular shape, while the new one makes provision for two 12.5 Mℓ reservoir compartments forming a single rectangular footprint to fit within the confined space available.
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IMIESA July 2020
The total dimensions for the entire reservoir are 100 m x 34 m x 7.5 m high. The two compartments each measure 50 m x 34 m. Included in the project scope are the inlet and outlet pipework and associated valve chambers. “Like the older reservoir, the client’s design brief was to construct the new one as a reinforced concrete structure,” explains Slater, who is the client’s engineer for the project. “While these are common across South Africa, their Achilles’ heel
Kendall Slater, principal civil engineer, Knight Piésold
is that the widespread use of expansion joints has traditionally made them prone to leaks.” Making provision for expansion joints inevitably results in discontinuity in the cast concrete. Traditionally, designers made provision for this by specifying the installation of rubberised water stops across each joint, as well as the installation of HDPE membrane liners. However, in many cases, leaks still occur because water stops often become misaligned when
