Marine & Coastal Infrastructure
Construction of a Pontoon, Boat Ramp & Carpark
Client
Hornsby Shire Council
Duration
August 2021 – October 2022
Location
Wisemans Ferry NSW
Expertise
Bulk Earthworks and Land Remediation, Concrete and Retaining Structures, Marine Works, Pontoons and Seawalls, Road Construction, Stormwater Drainage and Utility Services , Urban Spaces
After two major flood events, a new three‑lane boat ramp, expanded car parking and upgraded amenities were delivered to improve access to the Hawkesbury River and help attract visitors back to the area.
Project Scope
- Earthworks including demolition of existing amenities building
- Tree clearing mulching and removal and grubbing of roots and vegetation
- Service relocation – (Electrical ASP1 works)
- Existing Old Northern Rd box-out, compact and backfill
- Stormwater construction and upgrades to existing
- Sub-base and sub-grade compaction and backfill including Geotech testings
- Concrete kerb and ramps including sub-soil drainage
- Piling for the pontoon
- New concrete boat ramp and scour protection
- Carpark stormwater construction including kerb and gutter, concrete Islands and pavements
- Access concrete path
- Asphalting of widened road including primer seal, AC20 and AC14
- Carpark pavement including sign posting and line marking
- Landscaping
Key Challenges
Minimising the Impact of Flooding During Construction
Two major floods during construction resulted in sulfate soils and contaminated material that required site remediation. A cost‑effective solution was developed by creating on‑site contamination cells, allowing safe storage and continued progress despite the flooding impacts.
We also adjusted resourcing to support Council during funding delays and closely monitored rainfall and flood warnings to maximise safe working windows and maintain project momentum.
Successful Collaboration with Multiple Clients
With three clients involved, consistent communication was essential to manage flooding impacts and emerging site issues. Close collaboration with Hornsby Shire Council, Hills Shire Council and Transport for NSW enabled jointly designed solutions that aligned with funding constraints and project needs.
Working in Sensitive Waterways
The boat ramp and pontoon were constructed within protected mangroves along the Hawkesbury River, limiting traditional construction methods. To protect the mangrove environment, all piling and construction activities were completed from a barge, eliminating the need for a rock platform.
Innovative Design Changes for Best Project Outcomes
The original design specified precast concrete sleepers, which proved impractical due to underwater installation challenges and soft riverbed soils. An innovative redesign allowed the entire boat ramp to be cast in situ, using a cofferdam and rock platform to create a stable construction base and achieve a superior long‑term outcome.
