Lethabo Power Station, situated near Sasolburg in the Orange Free State, South Africa consists of six 618 Megawatt units generating a potential total electricity capacity of 3,708 Megawatt.

Technical details:

• Six 618MW units
• Installed capacity: 3 708MW
• 2001 capacity: 3558MW
• Design efficiency at rated turbine MCR (%): 37.80%
• Ramp rate: 33.33% per hour
• Average availability over last 3 years: 93.05%
• Average production over last 3 years: 21 572GWh

Lethabo Power Station has been built on 11 000 concrete piles which were sunk 25m deep. The reason being to alleviate the heaving clay problem after some 190 000 blue gum trees were removed during site clearing operations. At the time, it was the largest piling contract ever awarded to a South African contractor. The station is 16 years old this year.

Lethabo Power Station Instrumentation consists of the following:

• Vibrating Wire Settlement Cells measuring settlement.
• Vibrating Wire Piezometers measuring pore pressure.

Instruments installed are intended to monitor:

• Settlement;
• Pore pressure build-up.

Installed Instruments Specification:

Settlement cells (Pile Structure)

• Geokon Vibrating Wire Model 4650

Piezometers (Clay Core against Retaining Wall)

• Geokon Vibrating Wire Model 4500S

Designers: N/A

Consulting Engineers: Roshcon

Contractors: N/A