Westwood Estate’s Four MegaVaults: Inside a 3.2 Megalitre OSD

A master-planned residential development with a back doorstep view of the scenic Blue Mountains, Westwood Estate is an 11.5-hectare site in Caddens, City of Penrith.

Bordered by Kingswood, Orchard Hills, and Claremont Meadows, and situated close to Western Sydney University’s Werrington South campus, this iconic neighbourhood development will see 119 premium lots developed into a sustainable community centre.

A showcase of urban planning, the site will feature various scenic walking trails, bike tracks, and a golf course and is closely situated to nearby community infrastructure – which includes a local public school and shopping centre. With diverse home types and frontages, this development reflects family-friendly living in a pristine suburban setting.

Contained within the City of Penrith LGA, sustainability strategies support local growth, known as the ‘quadruple bottom line approach’, which balances people, the environment, the economy and governance.

High-Volume OSD & Efficient Installation Timelines

Stormwater outcomes are essential deliverables for developments in the City of Penrith LGA. With nearby watercourses, which include Werrington Creek and Werrington Lake Reserve, on-site detention assets are crucial for managing local stormwater flows.

On-site Stormwater Detention (OSD) is a mainstay of water quantity management and temporarily stores stormwater runoff flowing from impervious surfaces in urban areas, such as roads, driveways and concrete paths. Detention systems are developmental requirements that reduce the impact of stormwater by controlling its movement and slowly discharging it to drainage systems, groundwater, or nearby waterways.

Four Atlan MegaVault systems will provide OSD across the estate with a combined volume of 3.2 megalitres (ML) – with individual volumes of 1.8ML, 0.71ML, 0.5ML, and 0.2ML. The MegaVault offers cost-effective, efficient stormwater management for medium to large-volume detention scenarios.

The MegaVault systems will be situated under bioretention systems on four corners of the site, allowing stormwater flows to infiltrate and slow. The assets will future proof the estate, protecting the community by preventing localised flooding in storm events and severe downpours.

Locally manufactured at Atlan’s concrete facilities, these precast concrete systems have a design life of 50 years. Each MegaVault features a 3-metre internal height with superior depth capabilities and has been designed with a high-volume vertical profile to reduce horizontal footprint.

With their placement below the site’s bioretention systems, the design of these systems will maximise land yield – while meeting requirements for catchment size and flow rate. These generational assets are ideal for the available footprint with their ability to cater to large volume scenario – and their load-bearing structures will allow the continuation of above ground works

The MegaVault’s modular, precast design and offsite fabrication ensure ease of installation, which reduces project timelines and aids engineers. These project efficiencies and expedited timelines are benefits of this cathedral-style detention system – which has no internal walls.

A 73-module, 1.8 megalitre system was the first installation on the site, which took four days to install. Subsequently, each tank will have similar installation times – compared to weeks to months to install cast-in-situ alternatives.

This modular design will see dramatic project efficiency gains across all four installations, reducing open excavation times and wet weather delays across the entire development. Fully trafficable, these systems also ensure aboveground works can continue.

A scalable OSD solution, the MegaVault is suitable for a full range of residential, commercial and industrial applications. With load ratings that accommodate heavy traffic, these modular systems are ideal for underground scenarios with allowances for overhead infrastructure – such as parklands, car parks and roads.

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