Hunter River Remediation Project (HRRP)

Heron’s ocean going tug Kurutai departed Auckland on Christmas Eve 2009 with hopper barges H7 and H8 bound for Newcastle, she then steamed back to Lyttelton, New Zealand to collect the backhoe dredge (BHD) Machiavelli.

After towing the Machiavelli the 1380 Nautical miles from Lyttelton to Newcastle, the Kurutai set course to Adelaide to pick up the split hopper barges WH761 and WH762 and tandem tow them back to Newcastle. The final stage of the mobilisation was to return to Tauranga, New Zealand for the BHD Kimahia. When the Kurutai arrived in Newcastle with the Kimahia she had successfully completed five trans-Tasman and two inter-state voyages totalling over 8,500 nautical miles without incident.

This dredging project was complicated by the existence of Polycyclic Aromatic Hydrocarbons (PAH’s) such as naphthalene, Total Petroleum Hydrocarbon (TPH’s) and heavy metals to a lesser extent in the river sediments. All dredging activities took place behind a sheet-pile wall which isolating the dredging zone from the Hunter River.

To minimise the migration of contaminants during dredging the BHD’s Machiavelli and Kimahia used a combination of environmental grabs specially imported from the Netherland and open buckets where contamination levels allowed. 800,000m3 of contaminated sediment was dredged with the BHD’s Machiavelli and Kimahia, loaded into sealed hopper barges and manoeuvred to the unloading facility within the confines of the sheetpile wall before being trucked to processing plants for stabilisation with cement.

The HRRP Project received national recognition in the United Nations Association of Australia World Environment Day Awards in 2011 when it was announced as the winner of the UNAA’s Environmental Best Practice Program Award.