Spring Grove Dam, situated in the Mgeni Water System in KwaZulu-Natal, South Africa is a Roller Compacted Concrete Dam (RCC), with a 607m crest length. The structure includes a free crest spillway with a crest length of 70m over RCC. The dam structure futures a rock-fill clay-core coffer wall/embankment stretching 325m.

Spring Grove Dam was constructed by Group 5 Pandev Joint Venture and has an active storage capacity of 139.5 million m³.

Spring Grove Dam Instrumentation consists of the following:

• Vibrating Wire Embedment Strain Gauges in the RCC measuring strain.
• Vibrating Wire Long Base Strain/Jointmeters measuring over induced joints.
• Vibrating Wire Thermometers measuring temperature.
• Thermistors measuring temperature.
• Six Vibrating Wire Rod Extensometers (inclined and horizontal) measuring zone movement and tilt.
• Vibrating Wire Foundation Piezometers for measuring pore pressure.
• 28 individual 3-D Mechanical Crackmeters measuring three-dimensional movement on the crest.
• Vibrating Wire Transducer measuring seepage.

Instruments installed in and around the Dam Embankment are intended to monitor:

• Tilt of the Dam;
• Measuring movement over the induced joints;
• Stresses and strain of the concrete;
• Total downstream seepage;
• Pore pressure build-up in foundation;
• Lake level water height.

Installed Instruments Specification:

V-Notch Weir (Dam, Outlet works)

• Soils Vibrating Wire Transducers Vented Model 4580

Piezometers (Clay Core and RCC Dam Wall)

• Soils Vibrating Wire Model W9-50-SST

Joint Meters (Rcc Joints center spillway)

• Soils Vibrating Wire Model ST-JI-4-1000

Strain Gages (Centre Rcc Wall and flanks)

• Soils Vibrating Wire Model ST4-S250-3-1

Standpipes (Manual measuring holes downstream from dam)

• Geotechnical Instrumentation Casagrande Standpipes

Rod Extensometers (Spillway)

• ITMsoil Vibrating Wire Transducers Model E7-1.1-6

Thermometers/Thermistors(Up to Downstream in Rcc)

• Soils Vibrating Wire T3-1.1/TM1-75

3 D Crack meters Manual

• Geotechnical Instrumentation 3D Crackmeter with Dial Gauge

Data Acquisition System CR800/1000 (Valve House)

• ITMSOIL Data Logger CR1000

Designers: BKS

Consulting Engineers: BKS

Contractors: Group 5 and Pandev Spring Grove Joint Venture