About 50 litres of a highly corrosive chemical used to preserve wood spilt on to a transport depot in Mount Maunganui early today. A 1000-litre plastic container of the chemical, known as Blue Control OC Antisapstain, was being unloaded about 4am on Aviation Ave from a truck when it is believedthe spill happened. The truck was sub- contracted by company Rapid Roadfreighters to transport the container from Auckland to Tauranga. Branch manager Jeff Burroughs said it did not appear the container had been damaged in transit but how or why the chemical had spilt at the distribution depot was unclear. The chemical was due to be transported from Tauranga to Kawerau. Mount Maunganui Fire Brigade station officer Peter Clark said about 5 per cent of the container had been lost on to the concrete. However, firefighters from Mount Maunganui and Greerton had prevented the chemical from flowing into the stormwater system and out to sea. "We put absorbent on it and stopped it from going to the harbour," Mr Clark said. "We've put it in a holding drain and now we'll pump it out from there." Firefighters wearing breathing apparatus, protective overalls and gumboots flushed about 4000 litres of water into the drain before pumping the diluted chemical into a tanker for removal. Firefighters were still working at the scene at 8.30am. A decontamination shower was set up at the site for firefighters to go through. Mr Burroughs said he was yet to speak to the driver of the truck carrying the chemical but an internal investigation into the incident would be conducted.