Case Studies > Hotel Rottnest- ProTank®


Date:        August 2020

Location:  Rottnest Island, WA

Product:   Modular ProTank® System


Project Background

The Rottnest Island Authority granted developers, Prendiville Group, approval for a new hotel to be situated on WA’s historic & much-loved holiday island. Hotel Rottnest’s existing accommodation would be replaced with 80 newly designed suites & adjoining public facilities. The hotel model and operations have a strong focus on sustainability. The design reflects the Rottnest’s geography, marine environment and complements the island’s historic setting.

The project is a major milestone for the future of Rottnest Island and will enhance the experience for locals and visitors to Western Australia and offer a resort that diversifies the Island’s current ageing accommodation.



Given the significant increase in hard surface areas across the new outdoor footprint, storm-water accumulation was of major concern. The catchment design also needed to consider Rottnest Island’s higher rainfall volume & intensity compared with its adjacent mainland city of Fremantle.  The preceding layout did not sufficiently consider seasonal rainfall events, resulting in adverse overland flow and subsequent erosion issues.



The ProTank stormwater management system was selected to satisfy the more critical hydraulic requirements of the project. Below ground volume and infiltration calculations were the main drivers behind the stormwater design, with attenuation being vital to overflow mitigation. The modular aspect of the ProTank system also enabled the required levels to be achieved whilst maintaining the minimum storage capacity.

The suggested design provided a significant reduction in overall cost, whilst ticking all the performance boxes for the project.

Benefits of ProTank®

  • Manufactured from premium quality recycled resin to meet the most demanding performance requirements.
  • The generous internal and surface void area provides optimum storage and infiltration speed.
  • Easy access via specially designed ports on every surface of each module.  This ensures trouble-free access and maintenance.
  • No requirement for imported drainage aggregate or special fill.
  • Compact & low-cost transportation thanks to ProTank’s flat-pack design.
  • Lightweight with rapid & safe installation.
  • Can be installed as ‘single block gallery’ or ‘finger gallery’ to accommodate a variety of hydraulic conditions and space allowances.



Selected Plumbing & Civil installed the ProTank system well within the contract timeframe, commending its ease of transport, assembly & installation. Global Synthetics in-house design team also provided the contractor & stakeholder with improvements to the original design at tender stage, motivated by the cost & performance benefits of ProTank.

Choosing the right stormwater management product for your application will depend on a range of factors. For assistance in choosing the right product for your individual project, contact the specialist engineering team at Global Synthetics.

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