Client: Sisters of Mercy
Project: Windsor Road Subdivision
Location: 522 Windsor Road, Baulkham Hills
Services Delivered: Concept design and options, DA design, civil design (roads and stormwater), project management and superintendency
Project Overview
The Windsor Road project demonstrates how strategic subdivision design can serve both community housing needs and site-specific challenges. This 12-lot residential subdivision was developed for the Sisters of Mercy to create funding for secure housing for a seniors living and disadvantaged women.
The project’s importance extends beyond typical residential development – it enables the Sisters of Mercy to give back to the community by establishing seniors living facilities while maintaining their existing community presence. The residential lots will generate revenue to fund the construction of two future seniors living buildings, creating a sustainable model for community housing development.
Diversi’s civil engineers and infrastructure engineers were engaged to deliver comprehensive engineering services from initial concept through to construction completion, including roads design, stormwater infrastructure, and ongoing construction management.
Design & Engineering Challenges
Site Topography: The primary constraint was the site’s very steep slope and awkward shape, making it extremely difficult to achieve an efficient subdivision layout with good lot yield. Multiple design iterations were required to optimise the development potential.
Stormwater Management: A critical challenge involved managing stormwater discharge through an easement that runs through the adjacent school property. This required careful analysis of existing drainage capacity and coordination with school operations to ensure downstream flooding wouldn’t occur.
Contamination Issues: Discovery of asbestos contamination, including material buried beneath trees that couldn’t be removed, required specialised remediation approaches working within arborist-defined root protection zones. Else where on site the unexpected finds and contamination was mapped and removed from site.
Heritage and Environmental Constraints: The client’s commitment to preserving existing trees created additional design constraints. As the original tree planters, the Sisters insisted on retaining as much vegetation as possible and reusing bricks from demolished buildings as feature walls.
Our Engineering Solutions
Civil Engineering Innovation: Rather than relying on conservative assumptions about downstream capacity, our civil engineers collaborated with council to conduct CCTV surveys of the existing pipeline network. This data-driven approach allowed us to model actual capacity rather than assumed limitations, optimising our stormwater detention system design and reducing over-engineering.
Advanced Civil Engineering Design: Our infrastructure engineers incorporated strategic earthworks and retaining wall systems to create more developable lots with acceptable grades (3-4%) rather than the original steep terrain that would have resulted in 10% grades unsuitable for residential development.
Urban Planning Integration: Close collaboration between our urban planning engineers, surveyors, arborists, and contamination specialists ensured all development constraints were managed effectively. Multiple site surveys were conducted to pin down exact requirements and preserve as many trees as possible while meeting subdivision planning requirements.
Access Optimisation: The subdivision design incorporated closing the existing Windsor Road access as required by DCP conditions, with new access via St Michael’s Place, requiring careful coordination with adjacent school operations.
Project Outcomes & Community Impact
Sustainable Community Development: The project creates a funding model that enables ongoing community support through secure housing for disadvantaged women, demonstrating how residential development can serve broader social purposes.
Infrastructure Engineering Excellence: Our innovative civil engineering approach to stormwater analysis resulted in more efficient infrastructure design, avoiding over-conservative solutions while maintaining safety standards and regulatory compliance.
Heritage Integration: Successful preservation of mature trees and integration of recycled heritage bricks from the original covenant buildings maintains the site’s historical character while enabling development.
Knowledge Transfer: The project included an innovative site visit program where the entire design team visited the construction site for experiential??? learning, helping junior engineers understand how their computer-based designs translate to real-world construction.
The completed subdivision will provide 12 residential lots while preserving the Sisters of Mercy’s community mission and maintaining the area’s established character through thoughtful design and integration of historical elements.