Perry Park
Managing site conditions and risks to deliver a quality synthetic surface
Queensland

We found that the site had received uncontrolled filling in the past, with a weak ash layer at depth. Our challenge was to design an affordable solution that also offered a degree of comfort to the Council that the proposed synthetic turf surface would not settle.

Various organisations have completed cost-benefit analyses of synthetic turf surfaces. It shows that the investment only makes sense if the base is built to withstand multiple turf renewal cycles. The weak soils at depth at Perry Park would require a non-standard base to be designed and constructed to maximise its lifespan.

On a site like this, designing out all risks of settlement would be prohibitively expensive, so a decision was made as to the level of risk (and thus warranty period) that the Council would accept.

SPORTENG devised subgrade preparation and base construction options. It was agreed to issue the project as a Design and Construct contract, pushing the liability back onto the Contractor, but with SPORTENG providing indicative construction options. We designed a multi-layered pavement with a geo-grid between each layer for stability. We also minimised the removal of the upper surface as this was where most of the strength was found in the existing profile.

GrasSports was awarded the contract to build the field. They constructed the base using two layers, stabilised with a geogrid. The risk of settlement on this site has not been engineered out entirely, but the design means that if there is some localised settlement, the surface won’t be ruined.

At Perry Park, drainage is managed at the surface through a drainage cell. If localised settlement occurs over time, the turf and drainage cell can be lifted, the depression filled, and everything replaced, allowing the field to be quickly restored to full use.

The field area was formally opened by Adrian Schrinner, Brisbane’s Lord Mayor on 15 February 2022, with players taking advantage of the high-quality surface for social and formal football.

This is a great example of how an engineered base does not need to follow a standard recipe. A bespoke option can still be workable, affordable and suited to the specific site conditions with a strong understanding for all stakeholders as to risks and possible maintenance requirements.