Mangdechhu – I Hydroelectric Project
The Mangdechhu hydroelectric project is a 720 MW run-of-river power plant being built on the Mangdechhu River in Trongsa Dzongkhag District of central Bhutan. The project comprises of a 101.5 m high concrete gravity dam from the deepest foundation level, two intake tunnels of 196 m and 150 m length, and a 13.54 km long headrace tunnel capable of discharging 118 m³ of water per second. The 152 m high surge shaft has a diameter of 13.5 m. Water is fed to the underground powerhouse through two steel-lined pressure shafts (1,853 m long and 3.5 m in diameter). The main cavern of the underground powerhouse is 53 m high and 231 m long.
Encardio-rite was awarded the contract for monitoring of dam, powerhouse, intake, desilting chamber, surge shaft, pressure shafts, and adits. Turnkey services included:
- Supply of geotechnical instrumentation for the dam and powerhouse
- Installation services
- Online monitoring of critical parameters and areas
- Manual monitoring
Instruments used:
- Piezometers: To monitor uplift pressure below the dam & pore pressure of water in the dam body
- Strain meter group: To monitor concrete stress and strains
- Perimetric and uniaxial joint meters: To monitor linear movement between the block joints
- Temperature meter and tele-thermometer
- Borehole extensometers: Multi-point and single point installed to monitor deformations
- Normal and inverted plumb lines: To monitor tilt of the dam
- Load cells: Anchor bolt load cells installed to monitor load on anchors
- V-notches: To measure seepage water flow collected in drainage channels
- Survey markers and settlement points
- Automatic data acquisition system: Commissioned for logging data from the above sensors
- Strong motion accelerometer: To monitor accelerations in the earth due to reservoir seismicity