TBM Florence was halted on May 16 when she encountered hard and abrasive rock that impinged the shield. Since May 21, specialist contractors have been using high-pressure water jetting to remove the rock.
Earlier this month Snowy Hydro reported that TBM Florence had moved forward in small increments several times and the machine remained fully operational.
Florence is excavating the 16km headrace tunnel which will connect the underground power station to the upper Tantangara reservoir on the New South Wales pumped hydro project.
The Snowy delivery team says it expects further highly variable ground conditions so progress will continue to vary, particularly as Florence navigates the curve leading to the main tunnel alignment.
Meanwhile, TBM Lady Eileen Hudson, which has completed the 2.8km main access tunnel to the power station, has reached halfway in excavating the 6km tailrace tunnel. This will connect the underground power station to the lower Talbingo reservoir.
A conveyor belt extension and service modifications have been carried out recently so excavations to join the tailrace tunnel with the Talbingo intake excavation can commence.
TBM Kirsten continues to excavate the 1.6km inclined pressure shaft (IPS), which connects the underground power station to the headrace tunnel that leads to the upper Tantangara reservoir. Kirsten has installed 14 trial rings in the IPS, using locally manufactured concrete segments designed for the high water pressures that will be experienced in the IPS.
The Snowy team says tunnelling the IPS will be a pioneering engineering challenge as the shaft’s incline reaches 47%.
Excavation of the Marica surge shaft, which will be one of the largest shafts of its type in the world, has reached 95m. Mechanical excavation, including rock breakers and excavators, and drill and blast continues.
