An ongoing investigation by Waikato Regional Council has today confirmed the source of unauthorised discharges of diesel into the Waikato River.

Regional council compliance and education manager Rob Dragten said the site has immediately put steps in place to prevent any further spills into the stormwater system.

“There is a complex maze of storm water drains which lead to the outlet near St Andrews golf course and so finding the source of the spill has been an incredibly difficult task.

“We have worked closely with Hamilton City Council over the past two days to identify the source. Staff from both councils have been lifting manhole covers, assessing drains in the catchment, as well as using CCTV inside the stormwater system.

“This has enabled us to track back up the network of pipes to find the point of discharge. Numerous samples have been taken from a number of locations over the past two days, and these will require further testing.

“It is pleasing to have been able to identify the likely source of recent unauthorised spills, and the organisation identified has been cooperating fully with our staff.

“But as this regional council investigation is ongoing, with legal action possible, it would be inappropriate for us to identify the source at this time,” Mr Dragten said.

Meanwhile, booms deployed yesterday morning were removed from the mouth of the outlet, as well as the river, late this afternoon.

“While there is no longer any diesel discharging from the outlet, there is a possibility a small amount of diesel might still be sitting in the stormwater system which is likely to be flushed out when it next rains,” Mr Dragten said.

Yesterday’s report of diesel discharging into the river from the Arcus Street outlet was the fifth in seven months.

Within an hour of receiving the report regional council staff had deployed absorbent booms across the mouth of the outlet. Higher river levels following rain meant it was unsafe for staff to immediately deploy the booms in the river. So the council’s harbourmaster assisted at the scene and another three booms were installed mid-morning.

“In addition to the three staff at the river, we had another five staff working alongside six from the city council to track the unauthorised spill source.

“By last night some positive progress had been made and we were able to eliminate a number of areas in the catchment, but further work has been required throughout today in an industrial area at Te Rapa,” he said.

“While we’re hopeful there will be no further spills into the river, this is a good reminder of the need for businesses to prevent toxic discharges from entering the stormwater system and ultimately the Waikato River.”