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Case Study
Brimbank Park
ENVIRONMENTAL WORKS
Project:
Keilor Outlet Main Cutting Rehabilitation
Location:
Brimbank Park, Melbourne
Client:
Streamline Australia
Streamline Australia called tenders for the rehabilitation of a cutting adjacent to the Maribyrnong River, Keilor. The cutting had been excavated earlier to allow for the construction of a 5km Sewer Outlet main associated with and under the Melbourne City Link Road Bridge. Rehabilitation of the cutting involved the stabilisation and associated revegetation of a 200m rock slope. As the works were in Brimbank Park the client was particularly interested in restoring the disturbed cutting to its pre-construction appearance.
A design and construct tender was called and we proposed a combination gabion/Terramesh solution revegetated using top soil and seed and protected using Terramat (Coil Fibre erosion control matting).
An innovative construction program enabled the wall to be constructed to full height (max 4m) along the full 200m despite the extremely limited space on the 3m wide access track. The contract was awarded after careful consideration of the alternative tenders and works commenced in August following completion of the detailed design submission.
The final detail incorporated Maccaferri rockfilled gabions stepped to match the existing ground profile whilst maintaining sufficient width for future pedestrian and cycle access. Particular emphasis was placed on restoring the original contoured ground profile so the gabion construction was completed based on a visual layout rather than a formal survey set-out.
During the sewer main installation selected sections of the cutting were supported using weldmesh and rock anchors. To provide additional support to the gravity gabion structure Terramesh panels were used to reinforce the backfill material and connect onto the rock bolt anchored weldmesh.
Once the gabion works had been completed the resulting terraces were filled with topsoil and covered with Terramat Erosion Control Matting (ECM). A range of alternative mat types were submitted to Parks and Waterways for approval however Terramat was chosen because of its excellent germination, mulching and strength characteristics. Some matting anchorage problems ere encountered on site due to the steep 1:1 batters and subsequent record rainfall floods.
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