This remediation project involved the excavation, stockpiling and disposal of over 5000 tonnes of asbestos and hydrocarbon impacted soils along with the dewatering, storage and treatment of in excess of 1 million litres of impacted groundwater.
The excavation involved careful benching to ensure the stability of the hole that extended to depths of 7m against an adjacent boundary. Impacted groundwater was managed by sump and pump techniques as it contained to recharge into the excavation from the adjacent property which was also contaminated.
Validation was completed in stages so that the excavation could be backfilled with imported VENM to stabilise the walls and also reduce the requirement for groundwater management.
Where possible cut off bunds and diversion channel where installed in the base of the excavation to separate impacted groundwater from storm water during the works. The separated storm water was tested to ensure if met reuse criteria before being used for irrigation purposes across the site. The process reduced the cost of the project by reducing the volume of water requiring treatment.
On completion of excavation and validation works a clay bund was reinstalled along the boundary of the site. A 500m wide, 4m deep and 30m long activated carbon interception trench was then installed along the boundary to mitigate any risk of impacted groundwater recharging from the adjacent site.