The landslide, triggered by heavy rainfall in early 2022, spans over 130 meters in width, is as deep as a five-storey building, with a depth movement exceeding 15 meters. Geotechnical investigations confirm it as one of the most significant landslides impacting a road asset in the Noosa and Sunshine Coast region in the last 30 years. Extensive damage lies beneath the surface, requiring a careful restoration process.

Hazell Bros is over half-way through driving 266 steel-lined bored piles, each with a diameter of 900mm, to a depth of up to 25 meters. This includes the installation of some of the largest soil nails currently used in the southern hemisphere. The scale of the project requires an estimated use of 6,000 cubic meters of concrete, equivalent to two and a half Olympic-sized swimming pools, and 800 tonnes of steel.

The comprehensive remediation effort involves:

• A large structural frame composed of two rows of contiguous bored piers (266 in total), connected by stiffening beams and a concrete road beam.
• Tie backs anchoring the frame into the upslope.
• Horizontal drains extending into the sub-surface materials.
• Additional upslope soil anchors and header beams, as needed.
• Concrete drainage works, incorporating pre-cast/cast-in-situ culverts and lined drains.
• Roadworks including drainage layers, pavement, surfacing, signage, guardrail, and line marking.
• Earthworks for embankment stabilisation.
• Service locations.
• Implementation of Erosion and Sediment Control measures.

The recovery works are jointly funded by the Australian and Queensland Governments through the Disaster Recovery Funding Arrangements (DRFA).

In 2016/17 Hazell Bros was engaged by MMG to upgrade the Rosebery Tailings Dam. Some of the works included:

• 36 hectares of clearing and grubbing
• 100,000m3 of topsoil stripping
• 1,000,000m3 of excavation in rock
• 2,500m3 of cement bentonite into a 600mm wide wall
• Installation of 190,000m2 of flexible bitumen liner

Awarded the Tasmanian Civil Contractors Federation Earth Award in 2018 - Category 5 Project value between $30M and $75M.

Built in 1971 of earth and rockfill construction, Conglomerate Dam has a storage capacity of 53.1ML. In 2017 Hazell Bros was engaged by TasWater to undertake an upgrade of the dam. Some of the works included:

• Installation of full height buttress filters and rockfill weighting berm
• Demolition of existing & construction of the new high capacity spillway 1:10000
• Raising the impervious level and crest level of the embankment
• Installation of multi-level intake structure with centralised valve operation
• Upgrading dam instrumentation and telemetry
• 25000m3 of imported and placed rock buttress and filter materials

2019 Cattle Hill Wind Farm (Goldwind)

This is the largest contract ever awarded to the business in its own right.

Works included 48 turbine footings, each averaging 450m3 of concrete; 26km of access roads; crushing and screening of road building material on site; steel fixing; management of 40km of electrical reticulation cabling; construction of substation, including control building; and operations and maintenance building.

2007 Studland Bay Wind Farm (Hydro Tasmania)

Works included construction of 24km access roads; establish and operate two mobile concrete batch plants to produce 15,000m3 of concrete; construction of 25 16.6x16.6m reinforced concrete footings for the towers, each containing 40T reinforcing steel and 450m3 concrete; construction of 25 45x45m hardstands; design and construction of control building; construction of switchyard footings; installation of 25km of underground cables; and civil works for 5km of transmission line, including temporary access roads and pole footings.

2012/13 Musselroe Wind Farm (Hydro Tasmania)

Works included construction of control building and associate switchyard footings; construction of 45km of internal road network and associated local road upgrades; construction of 56 octagonal reinforced concrete footings for the towers; onsite quarrying of road building materials; establishment and operation of two mobile concrete batch plants; and establishment of a fully-equipped 80-person construction camp in Gladstone.

The joint venture project delivered an upgrade of the existing Berth 3E to make it suitable for operation, including berthing, mooring and stern-loading of a roll-on roll-off (ro-ro) ship up to a length of 212m, for both passengers and freight between Geelong, VIC and Devonport (new Spirit of Tasmania vessels).

The scope of the works under the contract included:

• Design and certification
• Demolition of existing structures
• Minor dredging of the berth pocket (approx. 45,000m3)
• Reclamation
• Revetment scour protection
• Wharf construction – piles, precast, in-situ decks
• Wharf furniture – fenders/ bollards
• Minor services – water, power, lighting and stormwater services
• Remediation of existing wharf elements

The project adopted the use of 8T rock bags as scour protection in the berth in lieu of large rock and associated additional dredging. This is the first time in Australia that these rock bags have been used in this application. The bags are also made from recycled materials and are filled with rock from a local Hazell Bros quarry.

The wharf piles are coated with a 3-layer polyethylene (3LPE) coating system to increase the durability of the piled structure and lower life cycle costs for the asset owner.

Works have been carried out with strict environmental monitoring to ensure compliance to relevant water quality, turbidity, noise and dust standards. Site reuse of material has been maximised where possible with dredge rock and concrete demolition waste being crushed on site and reused in the reclamation areas.

The project involves construction of the intake excavation and downstream portal for the first stage of a new water conveyance directing water from Lake King William down to the Tarraleah Power Station. The 2 excavation sites will eventually be connected by a tunnel to allow the water to be piped through the surrounding mountains.

A plastic concrete cut-off and wave bund coffer dam were first constructed to protect the intake excavation from the rising lake levels and allow excavation to continue unimpeded. Excavation of ~130,000m3 of glacial soil and ~120,000m3 of dolerite rock is required at the intake site to reach the invert of the future tunnel.

Ground support is required to protect the steep excavation batters at both excavation sites, with a significant amount of rock bolts and shotcrete to be installed.
The project is due to be completed mid-2024.

The project involved laying of approximately 50km of distribution pipeline for two irrigation schemes; the Don Irrigation Scheme which draws water from the Forth River, and the Barrington Irrigation Scheme from Lake Barrington.

The pipeline was constructed with buttwelded 20m lengths of DN560 and smaller HDPE pipe.
The pipeline accessed 123 privately owned properties with 69 property outlets installed.

Installation of the pipeline encountered high production cropping farms, extreme wet weather, hard rock, and water, service and road crossings.

The project was completed in 14 months.