Berg River Dam, situated in the mountains close to Franschhoek, Western Cape, South Africa is a 60m high Concrete Face Rock-Fill Dam (CFRF) with a 900m long crest length. During construction the river diversion works consisted of channels, a cofferdam and a training wall where the Main Contractor Berg River Joint Venture (BDJV) trained their personnel and honed their dam building skills.
Outlet works comprises of a dual wet and dry well with a multi-level intake tower that is 58m high and a 5,5m diameter concrete outlet conduit. The side channel spillway is 40m long and consists of a discharge chute, deflector bucket and plunge pool (maximum discharge capacity of 740 m³/s).
Dam capacity is 4 million m³ and a gross storage capacity of 130 million m³.
Berg River Dam Instrumentation consists of the following:
- Convergence points in the Outlet-Tunnel measuring expansion/contraction.
- Vibrating Wire Strain Gauges in and around the Outlet-Tunnel, measuring concrete and re-enforcing strain.
- Vibrating Wire Load Cells and Vibrating Wire Pressure cells around and on top of the Outlet-Tunnel, measuring total load and pressure.
- Vibrating Wire Piezometers in the Clay Core of the coffer wall/embankment, measuring pore pressure.
- Five sets of Vibrating Wire Perimetric Joint Meters are installed on crucial structural points on the plinth and the concrete face slab, measuring three-dimensional movement between the plinth and the starter slab.
- Eighteen Vibrating Wire Embedment Jointmeters are installed in the top parts of the various vertical joints of the concrete face slab measuring movement between the joints.
- Vibrating Wire Settlement Cells in the rock-fill for measuring settlement.
- Standpipe Piezometers for measuring water table.
- Vibrating Wire Transducer measuring seepage.
- Data Acquisition System CR800/1000 (Valve House).
Instruments installed in and around the Dam Embankment are intended to monitor:
Installed Instruments Specification:
- Settlement of the Embankment;
- Pore pressure within the Embankment and foundations;
- Opening of the concrete face slab joints;
- Stresses and deflection in the face slab concrete;
- Stresses, strains and convergence of the Conduit;
- Pore pressure build-up around the Conduit and Main Embankment.
- Seepage (Dam, Conduit and Spillway)
- • Geokon Vibrating Wire Transducers Vented Model 4580
- Piezometers (Foundation, Plinth and Conduit)
- • Geokon Vibrating Wire Model 4500S
- Joint Meter (Concrete face and plinth)
- • Geokon Vibrating Wire Model 4400
- Crack Meter (Plinth and starter slab)
- • Geokon Vibrating Wire Model 4420
- Strain Gages (Face and Conduit)
- • Geokon Vibrating Wire Model 4210/4200/4202
- Tilt Meter (Face)
- • Geokon Vibrating Wire Model 6350
- Pressure Cells (Conduit and Main Embankment)
- • Geokon Vibrating Wire Model 4800
- • Geokon Vibrating Wire "Fat Back" Pressure Cell Model 4810
- Settlement Cells (Fill)
- • Geokon Vibrating Wire Model 4650
- Convergence Meters (Conduit)
- • Geokon Model 1610 Tape Extensometer
- Data Acquisition System CR10000 (Outlet House)
- • Geokon Micro-1000 Data logger Model 8021
- • Geokon Multiplexer (MUX) Model 8032
Berg River Consultants (BRC), a joint venture between Ninham Shand
, Knight Piésold
and Goba Moahloli Keeve Steyn
Contractors: Grinaker LTA
, Wilson Bayly Holmes-Ovcon (WBHO)
, and Group 5