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)