The source of a major diesel spill which contaminated the Brunswick Valley Sewage Treatment Plant (STP) two weeks ago has been narrowed down to an area at the northern end of the Mullumbimby township.
But Byron Shire Council still has no leads on the culprit and is keen to hear from anyone in the community. An offender found to have deliberately discharged oil, petrol or diesel into the sewerage system faces a fine of up to $250,000.
Information from the public on the February 14 spill, which came close to closing down the STP servicing Mullumbimby and Brunswick Heads, is being sought.
Council’s executive manager for water and recycling services, Phil Warner, said they had narrowed the diesel discharge to the catchment of a sewage pumping station at McGoughans Lane at the northern end of the township, but it was not possible to pinpoint the source of the spill.
Mr Warner said that while the amount of diesel dumped was unknown, the fact it was visible in the STP meant it was larger than a single car or lawnmower.
Mr Warner said staff were quick to detect the discharge into the system. The problem was first detected during regular monitoring when staff noticed samples that were a reddish brown colour, a diesel smell at the plant’s inlet, as well as froth forming on top of the plant’s major process unit.
‘Workers at the plant were faced with having to minimise the damage to the microbes in the system that digest the effluent by controlling the pH of the plant. STP staff did very well to keep the plant operating during the incident and managed to bring the plant back to full operating capacity in about ten days.
‘And while the possibly illegal discharge damaged the STP system, the plant itself lost no capacity. All inflow during the spill period was treated through the plant, with no bypass directly into the river,’ he said.
Mr Warner said the plant treats the effluent using microbes and the impact of the diesel meant the micro-organisms in the STP had to overcome the toxic effect of the diesel.
‘There was always the risk that had the illegal discharge been larger, then short-term recovery may not have been possible,’ he said.
Some locals feared the discharge could have polluted nearby waterways after noticing reddish-brown water at Torakina beach, Brunswick Heads, late last month.
But Council’s environmental health officer Jon Rushforth said the recent reddish-brown discolouration in the water at Torakina, Marshalls Creek and Simpsons Creek was mostly caused by tannins released from ti tree leaves decomposing and being washed into the waterways during the recent heavy rains.
Mr Rushforth said the naturally occurring process permanently stained some natural water bodies such as Belongil and Tallow creeks at Byron Bay, and Lake Ainsworth at Lennox Head but was ‘not so much the risk of stormwater contamination, but the significant reduction in visibility through the water column which can affect bather safety’.
Mr Warner said the diesel discharge had to have been significant given the size of the plant.
‘The entire townships of Mullumbimby and Brunswick Heads, which together number about 6000 people, are connected to the plant. A plant the size of the Brunswick Valley STP requires a large volume of diesel to be affected the way it was,’ he said.
‘As a result, six megalitres of discharge (of treated effluent) across 48 hours were injected into the river that contained phosphorus levels above limits set by the Environmental Protection Authority.’
Mr Warner said the diesel discharge was a serious issue which council would vigorously investigate. He asked anyone in the community with information about the discharge to contact council on 6626 7000.
‘Uncontrolled discharges to the sewer of prohibited substances such as diesel can pose serious problems to public health, worker safety, council’s sewerage system and the environment,’ he said.