Proposed exploratory works

Snowy Hydro is currently seeking approval for an initial program of exploratory works that would be undertaken in the Lobs Hole area of Kosciuszko National Park. The works would consist of excavation of a tunnel to the location of the proposed power station cavern, along with associated infrastructure.

Overview

The underground power station for Snowy 2.0 consists of multiple large caverns, approximately 850m below ground level. The largest cavern (for the machine hall) is likely to be about 190m long, 30m wide and 55m high.

The underground cavern complex is one of, if not the most, challenging areas for the design of Snowy 2.0.

The purpose of the exploratory works for Snowy 2.0 is to gain a greater understanding of the underground geological conditions at the proposed location of the power station. An access tunnel would be excavated to the top of the cavern complex to enable horizontal investigation probes to be drilled, allowing further investigation of the rock conditions, ground temperature and stress conditions to confirm the suitability of the site for the underground power station.

The exploratory works would involve:

  • The establishment of an exploratory tunnel, construction pad and portal at the Lobs Hole Ravine area of Kosciuszko National Park,
  • The establishment of a construction compound and supporting infrastructure,
  • The upgrade and establishment of roads to provide access to the proposed construction areas,
  • The establishment of barge access infrastructure on Talbingo reservoir,
  • Excavated rock management.
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Access tunnel

The exploratory tunnel to the site of the proposed underground power station would be between 3km and 4km in length. It would be a dome shape with dimensions 8m high by 8m wide, and constructed using drill and blast methods in the same way that the original Snowy Scheme was constructed.

The portal to the exploratory tunnel would be located near the Yarrangobilly River, about 1km east of Lobs Hole.

A construction pad would be established at the entrance or portal with a footprint of between 10,000 and 16,000 square metres (m2).

The exploratory tunnel is intended to ultimately form the main access tunnel (MAT) for the main project, giving us access to the underground power station during the operation of Snowy 2.0.

Site access works

Access to the work areas will be provided via both vehicle and barge.  Vehicle access would be provided via Lobs Hole Ravine Road for movement of personnel and light equipment. Barge access would be provided via Talbingo Reservoir for the transport of bulky and heavy equipment.

Upgrades to roads and tracks in the area, including Lobs Hole Ravine Road, would be required to facilitate access, including some road widening, gravel pavement overlay and provision of guideposts.

Barge access will require the provision of wharf facilities on Talbingo Reservoir, both near the dam wall and near Lobs Hole.

For safety reasons, public usage of Lobs Hole Ravine Road would be restricted and returned to public use after construction.

Construction compound

A construction compound is proposed at Lobs Hole that would provide all supporting infrastructure for the exploratory works. The compound would include facilities like an accommodation camp, project office, workshops, concrete batching plant, fuel farm, laydown areas for equipment, water treatment plant, and sewage treatment plant. It would also contain areas for the placement of rock excavated during the construction of the exploratory tunnel.

The accommodation camp would house all the workers required for exploratory works (between 50 to 150 workers). The camp would be fully serviced and contain a mess hall and laundry.

During construction, the Lobs Hole area would not be safe for public access and would be temporarily closed to the public. After construction, Lobs Hole will be rehabilitated and returned to its current use.

Excavated rock management

It is estimated that approximately 500,000 to 750,000 cubic metres of rock would be excavated during the exploratory works. This excavated rock is expected to be temporarily stored in the construction compound area at Lobs Hole.

Final excavated rock placement and management will be determined following the scientific and technical investigations being conducted and will be addressed in the Environmental Impact Statement for the main project. Options being considered include beneficial reuse, as well as placement outside Kosciuszko National Park or within Scheme reservoirs.

Construction schedule

Exploratory works are expected to be completed within 18 to 30 months. Road and access works are expected to be completed within six months of commencement which is targeted for late 2018 or early 2019.

To view the exploratory works booklet click here.