With water quality ailing at Shellharbour landmark Flinders Green, Shellharbour City Council engaged Donnelley Civil to renew the pond opposite a large public park.

The Challenge: deliver the project effectively, efficiently, under budget and without environmental impact.

With 250 tonnes of general solid waste sediment in the basin, the project encountered several immediate challenges. The sediment material held moisture and would take a long time to dry, and there was a possibility the soil contained acid sulphates. These concerns, combined with wet weather and a slope encumbering site access, so project members set about creating a plan.

The concrete sediment trap and detention pond were established as a target. A 35 tonne long reach excavator was employed, creating a large 20 metre cleaning radius. Spreading the excavated material and maximising stockpile area, cut excavation time in half and provided an ideal setting for treatment.

In consultation with an environmental specialist, lime was identified as a solution to dual issues. Neutralising the sediment and allowing it to dry quickly, the lime also permitted the sediment to be classed as an excavated neutral material (ENM), making it reusable once taken off site.

Consulting with council, Donnelley Civil also modified site access, lengthening and reducing the slope. Despite unrelenting rain, the access allowed dump trucks to be used to remove waste, cutting handling and logistics timelines.

Completed ahead of the council’s schedule and $30,000 under budget, the renewed pond was delivered without incident. Now offering Shellharbour locals a view of clearer, cleaner water, the park remains a centre for community activity.

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