Following the successful completion of a field-based technology trial last year, Ventia has been awarded the contract to deliver the Kendall Bay Sediment Remediation Project for our client Jemena.

Our Environmental Services team has worked over the past two years to engineer a long-term solution for Jemena that aims to minimise the impact on the environment and the local community.

The innovative remediation solution addresses legacy coal tar contamination from the former Mortlake gasworks using in-situ solidification to stabilise the contaminated sediments in the bay, reducing risk to human health and the environment. 

This is one of the first times in-situ stabilisation has been used to remediate contaminated marine sediments on a large scale anywhere in the world. 

Ventia is excited to be at the forefront of advances in the use of in-situ stabilisation technology into underwater environments. This method of remediation delivers value to our client, while also minimising the impact to the local residential community through reduced truck traffic in and around the area.

Following the stabilisation of contaminated sediments, clean sand and rock will be installed to provide a suitable environment for the recolonisation of the remediation areas by microorganisms in the sea bed. Works also include removal of coke and other impacted materials from the surface sediments, followed by the installation of stormwater controls and the replenishment of clean sand and rock to rejuvenate the remediation areas adjacent to the former gasworks.

One of the challenges the team faced during the field-based trial in Kendall Bay involved the complexities presented by working in a shallow marine environment. The project team was required to contend with wind, waves and tides while operating large plant and equipment from floating barges. The field-based trial was a critical step in the design of the solution for full scale remediation and scheduling works so that efficient productivity can be achieved.

The Ventia project team also had to work around the challenges of mixing cement into the sediments under water because interaction of the seawater with the cement mix affects the ability to achieve appropriate stabilisation of the contaminated sediments. This problem was overcome by refining the ratio of additives and adjusting the methodology. 

Working in a sensitive marine environment also requires the design and implementation of a comprehensive real-time water quality monitoring program and strict environmental controls.  The Ventia team has utilised their marine remediation experience to design a best practice environmental control system around the works, including a series of steel sheet pile walls, silt curtains and oil absorbent booms which will surround the sediment stabilisation works.

Ventia looks forward to delivering this innovative sediment remediation project for our client Jemena and for the benefit of the local Breakfast Point community.