A WDC spokeswoman said that since October last year, about 200,000kg of containerised, contaminated water has been collected, treated and disposed of at a facility in Auckland.
About 22,500kg of contaminated waste has also been taken away for disposal.
At present, 2944 of an estimated 4200 containers with solvents have been sampled and assessed and data is being used to determine the appropriate disposal location for the contents of each container.
She said six 20,000-litre chemical transfer tanks have been filled with solvents and taken off site. Two of the tanks have been delivered to a disposal facility while the other four are in a storage facility awaiting shipment.
Drum crushing and sludge mixing has started and they will be sent to a landfill in Auckland once processed.
"The removal of these hazardous substances safely, following all requirements and obligations is paramount to the protection of our environment," the spokeswoman said.
"This work has proceeded with no significant health and safety or environmental issues for the staff on site or for the wider public in this area.
"This is quite an achievement given the hazardous nature of this site and the materials being removed and can be attributed to respective parties taking the time to plan and prepare work methods."
WDC intends to recover the clean-up costs from the site operators.
