Finn Valley was commissioned by Transport for New South Wales to replace multiple culvert sites along the Oxley Highway, Mount
Seaview west of Wauchope. The project scope included but was not limited to:
During the first phase of the project, Finn Valley was tasked with completing 8 HDPE culvert crossings in a known naturally occurring
asbestos (NOA) area. Despite constant spoil monitoring and air sample testing, which consistently tested negative for NOA, Finn Valley
remained vigilant. They ensured that all workers wore the correct personal protective equipment (PPE) to maintain safety and health
standards in the work area.
In phase two, Finn Valley was initially responsible for 7 HDPE culvert crossings. However, TfNSW requested an additional two culverts
under a variation order due to the condition of existing culverts and Finn Valley’s proximity to the works. This phase presented
challenges, including road alignment curvature and maintaining proper lane widths. These challenges were crucial to ensure that
trucks could maintain a straight path as long as possible before navigating corners without damaging vehicles or guardrails. Finn Valley
managed this by maintaining constant communication with traffic control crews and conducting regular walkthroughs with their
supervisor and the traffic control team leader to discuss appropriate traffic management strategies. This ensured everyone’s safety
while allowing work to proceed on schedule.
Phase three of the project involved a total of 10 HDPE culverts spread over a 16km stretch of the uphill Oxley Highway. Since these
culverts were not close to each other, Finn Valley had to establish and disestablish their setup five times across different locations.
They completed the work methodically to prevent the creation of unmanned work zones.
In phase four, Finn Valley was tasked with extending a single cell 1500mm culvert by 2.4m on either side of the highway, including the
construction of two cast-in-situ headwalls in a gully with constant water flow issues. These issues were managed by installing bypass
pumps and using ERSED control measures to pump the water. Due to poor drainage of the existing inlet, the ground underneath the
new works was quite soft, necessitating the installation of a geofabric-lined rock mattress to prevent further damage.
Before completing phase four, TfNSW requested additional variation works, including one more HDPE culvert crossing and four scour
protection spillways. Finn Valley ultimately completed a total of 28 HDPE culvert crossings, pouring cast-in-situ slip form pits on 26
inlets, and two cast-in-situ headwalls on the remaining inlets. They also poured angled cast-in-situ headwalls on all outlets and
shotcreted a scour protection spillway on a steep batter at each outlet while working off ropes and harnesses. Existing outlets were
sealed with shotcrete to allow RCP culverts to be filled with grout, preventing further highway collapse. After grouting, mass concrete
was poured over the top of existing pits to match the kerb profile, ensuring water flowed correctly into the newly installed works. The
project was completed on time and within budget with zero defects.
