Isabella WeirWinner of 2019 CCF ACT Earth Award Project $10M – $30M Winner MBA Building in Excellence Award 2019 Civil – Other Due for completion in late 2018, there are two parts to this significant project; Construction of two wetlands in the existing Isabella pond as a part of the ACT Healthy Waterways scheme and the widening of the existing labyrinth wall weir forming the dam wall for Isabella pond. The aim of the Isabella Ponds Wetlands project is to improve the quality of the water at both the incoming pond areas as well as the outgoing water into the Murrumbidgee River system; the wetlands ponds will create a haven for flora and fauna. The weir is being widened to allow for higher flows, thus greatly reducing the risk to downstream stakeholders of Tuggeranong. The additional flow capacity of the weir also reduces the risk of damage to the Drakeford Drive Bridge. The key activities of the new upgrade include the demolition of the exiting abutment and labyrinth wall and then the reconstruction of the reinforced concrete structure.
John Gorton Drive John Gorton Drive completed in November 2016 remains the largest construction project undertaken by Guideline ACT. As a significant arterial road, the scope of work included the construction of a divided dual lane arterial road, extending the newly constructed John Gorton Drive further north approximately 1.5km from Coombs to Denman Prospect, including two significant single span bridge structures, trunk sewer and water main, permanent water feature ponds, temporary silt ponds service relocations and signalized intersections. The project facilitated the accreditation of OFSC for Guideline ACT and received numerous awards during and after its construction.
Cravens Creek Water Quality Control Pond The Molonglo Valley urban development Stage 2, which is expected to accommodate approximately 55,000 residents over the next 30 years, required various preliminary infrastructures. The Cravens Creek Water Quality Control Pond has formed part of that infrastructure, acting as an intermediary between the Molonglo River and the potential overland flow of the surrounding residential developments. Key components of the Cravens Creek WQCP construction include the embankment – constructed as six tier, layered earthen dam with materials ergonomically sourced from onsite excavations, the primary spillway – a 500m3 cast in situ concrete spillway comprised of an intake tower, outlet conduit and steel arch inlet cover, internal drainage point for future maintenance and concrete stilling basin with surrounding gabion mattresses and walls designed to ensure dissipation downstream of the spillway. The WQCP has been designed to withstand and manage discharge rates up to the design 5 year ARI event and convey peak flows up to the 20 year ARI event through the primary spillway. To account for greater ARI events a secondary spillway has been constructed in the form of a grassed channel to attenuate the flows from 20 year ARI event up to the 10,000 year ARI event. The project was completed in 2016.
Googong Bulk Water Offtake Works involved the delivery of a DN450 offtake cut into the DN1800 bulk water pipeline. The new connection includes 30m of new DN1800 pipeline inclusive of 2No.DN1800 butterfly valves, bypasses, scours, DN450 offtake manifold and construction of valve chamber. The DN450 offtake manifold connects to the Bulk water pump station suction main at the tie in point adjacent to the Bulk Water Pump Station building and then pumps to the new township of Googong supplying uninterrupted drinking water.
Lyneham & Dickson Wetlands The project involved the construction of the Lyneham & Dickson Wetlands and associated works including pump stations. Completed in 2012, the project involved the construction of the Dickson & Lyneham Wetlands and associated works including pump stations. The Lyneham & Dickson Wetlands were part of a suite of wetlands to be constructed in the Sullivans Creek Catchment. The wetlands consist of a large landscaped stormwater retention basin at both sites complete with inlet and outlet structures and a pump station, with the future aim of harvesting the stormwater and using it to water the local sporting fields. The pond area includes shared paths, new pedestrian footbridges and the realignment of the main community footpath route. The main purpose of the Lyneham & Dickson Wetlands project is to provide water quality improvements, water for irrigation, increasing aquatic and terrestrial habitat in urban areas and creating recreational, volunteering and educational opportunities.
Tharwa Bridge Upgrade Stage 2 – Substructure and Approach Spans Strengthening Completed in 2010, Tharwa Bridge Upgrade stage 2- Substructure and approach span strengthening project involved strengthening the 115 year old bridge as part of an overall project to restore the bridge to its former glory and increase its load bearing capacity without affecting its heritage value. The project involved a number of factors making it “more than a simple construction job” because of the heritage value, the environmental factors associated with working over flowing water, and emotional impact as the bridge is an iconic structure deeply embedded in the Tharwa community psyche. The work involved strengthening 5 existing concrete pier foundations by way of jet grouting and ground anchors, strengthening the remaining 6 piers via carbon fibre straps to the head stock and replacement of both abutments including foundations. Strengthening the approach spans was achieved by installing additional steel girders for spans 1 to 5 and 10 to 12.
National Arboretum Canberra, Central Valley Earthworks Completed in 2010, the construction of the Central Valley, an 8 hectare section of the National Arboretum Canberra project, where a series of 36 earth terraces down the side of a hill create a dramatic public garden of international interest. The construction team, Guideline ACT, brought its engineering expertise to a large scale work of art ensuring the design intent was delivered, constructing the terraces to sound engineering principles.
Cotter Dam Remedial Works Cotter dam, a mass concrete gravity dam, was constructed in 1912 and was raised in 1949. Concerns about ageing and structural integrity of the dam were broached as early as 1967 and with the revision to the probable maximum flood and earthquake requirements of 1 in 10,000 years, plus the proximity to a popular recreational resort, the decision was made to strengthen the dam. The aim of the Cotter Dam Remedial Works project was to strengthen the wall of the mass concrete gravity dam by replacing the top of the existing wall. Scope of works:
- The spillway section of the dam wall was removed to 1.5m below the original level and the abutments were removed to 1.8m below the original level for the full width of the dam
- Permanent post tensioned re-stressable ground anchors were placed. The 45 anchors, ranging in length from 20m to 60m and weighing up to 2.5tonne, involved drilling 1800m of holes
- Form work was erected and the concrete for each of the new load distribution beams was placed in two pours
- Water proof grouting and stressing the anchors
- Construction of a discharge facility