Picton Multi-Deck Carpark

Woolacotts was engaged by Wollondilly Shire Council to deliver civil, flooding, and traffic engineering services for the Picton Multi-Deck Carpark, a major upgrade to the existing on-grade carpark in Picton, NSW. The site is significantly impacted by 1% AEP flooding and is classified as ‘H4’ within the Flood Hazard Category, making it unsafe for people and vehicles under major flood conditions. The project aimed to deliver a modern, multi-level parking facility that improves accessibility and supports ongoing community growth while managing complex flood, stormwater, and traffic constraints.

The architectural design was led by Lockhart‑Krause Architects, with Kane Constructions engaged as the design manager and builder. Woolacotts was initially appointed to prepare design documentation and approval-phase reports for Wollondilly Shire Council and was subsequently engaged by Kane Constructions to deliver detailed civil construction documentation.

Across both phases, Woolacotts delivered TUFLOW hydraulic modelling to assess flood behaviour and impacts, preparation of stormwater management plans incorporating water-sensitive urban design (WSUD) principles, and a Traffic Impact Assessment supported by SIDRA intersection modelling. Swept path analysis and traffic design advice were also provided to support safe and efficient vehicle movements and compliant site access arrangements.

The project presented significant technical challenges due to the site’s exposure to major flood events, including 1% AEP and PMF storm scenarios. High-resolution flood modelling was required to accurately assess the impacts of structural elements—such as columns, ramps, stairs, and lift cores—on flood storage, flood levels, and flow paths. Achieving acceptable flood outcomes required careful balancing of hydraulic performance with architectural and structural requirements. Additionally, Stakeholders such as Wollondilly Shire Council and SES, were consulted to prepare flood emergency and evaluation procedures.

The Picton Multi‑Deck Carpark is a significant piece of community infrastructure that supports town centre growth while responding to complex flood and traffic constraints. The project demonstrates Woolacotts’ capability to deliver coordinated, technically robust engineering solutions across planning, approval, and construction phases, working collaboratively with architects, builders, and councils to achieve high-quality public domain outcomes.