Maguga Dam

Type: Rock-Fill Clay Core (RFCC) Dam
Construction Date: 1998 - 2002
Location: Hhohho, Swaziland
S 26.076906° E 31.259581°
Maguga Dam, situated near Pigg's Peak, Swaziland is a 115m high Rock-Fill Clay-Core (RFCC) dam with a 1328m crest length.
This dam structure forms is part of the Komati Basin Water Authority (KOBWA).

Main Embankment is split in two half's (320m and 628m) with a conventional formed concrete labyrinth (182m in length) and massive spillway (278m in length).

The two main clay-core embankments comprises approximately 800 000m³ of clay, 2 800 000m³ of granite rock and 43 000m³ of filter material.

Maguga Dam has been designed to withstand a probable maximum flood of 15000m³/s and the labyrinth spillway can pass a flood of 7800m³/s without sustaining damage.

The Dam Capacity is 26.7 million m³ with an active water storage volume of 19.1 million m³.

Maguga Dam Instrumentation consists of the following:
  • Convergence points in the Outlet-Tunnel measuring expansion/contraction.
  • Vibrating Wire Pressure cells on the Retaining wall measuring total pressure.
  • Vibrating Wire Embankment Piezometers in the Clay Core measuring pore pressure.
  • Vibrating Wire Foundation Piezometers measuring pore pressure.
  • Vibrating Wire Settlement Cells in the rock-fill for measuring settlement.
  • Standpipe Piezometers for measuring water table.
  • Vibrating Wire Transducer measuring seepage.
  • Vibrating Wire Rod Extensometer, measuring downstream movement.

Instruments installed in and around the Dam Embankment are intended to monitor:
  • Settlement of the Embankment;
  • Total pressure between the clay-core and the concrete retaining wall;
  • Pore pressure build-up in the embankment and foundation;
  • Total settlement of the dam;
  • Downstream and gallery seepage;
  • Downstream shift of the entire structure.

Installed Instruments Specification:
Piezometers (Foundation, crump weir, lake level)
Geokon Vibrating Wire Model 4500S
Pressure Cells (Retaining Wall)
Geokon Vibrating Wire Total Pressure Cells Model 4810
Rod Extensometer (Main Embankment)
Geokon Vibrating Wire Model 1280
Weir Transducer
Geokon Vibrating Wire Transducers Vented Model 4580
Data Acquisition System CR800/1000 (Valve House)
Geokon Micro-1000 Data logger Model 8021
Geokon Multiplexer (MUX) Model 8032

Designers: N/A

Consulting Engineers: Ninham Shand, Keeve Steyn, Vela VKE Engineers, SRK Consulting Engineers, ZMCK Consulting Engineers, Kagga & Partners and M&E Consultants

Contractors: Maguga Dam Joint Venture (MDJV)

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