Berg River Dam

Type: Rock-Fill, Face Slab Dam
Construction Date: June 2004 - July 2008
Location: Franschhoek, South Africa
S 33.908445° E 19.054198°
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:
  • 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.

Installed Instruments Specification:
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

Designers: A.L. Melvill

Consulting Engineers: 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 (BDJV)

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