The illegal dumping of a highly toxic chemical into the sewage system is severely affecting the sewage treatment plant.
The chemical kills the bacteria used in the sewage treatment process, which has led to bad smells emanating from the Water Authority’s plant near the Industrial Park.
It’s not the first time the chemical has affected the plant, and its origin remains a mystery. The chemical was behind the rank smell which overtook portions of the Seven Mile Beach area over the long Easter long weekend.
The system was affected so badly by the chemical during the Easter weekend incident that all of the friendly bacteria inhabiting the seven-million-gallon sewage treatment system were killed in a matter of hours.
‘One of the worst affected tanks is just starting to come back online now,’ said plant Operations Manager Toby Todaro.
The incidents started 26 November 2006 and have been happening every few weeks since then, always on a weekend at 2am and once on a Wednesday, said Mr. Todaro.
It happened again this past weekend.
‘During the Easter weekend incident, we had four feet of foam, some of which was even blowing over the top of the tank wall, the normally brown water was completely grey, and there was a really strong chemical smell,’ he said.
‘We are pretty sure it is the same chemical that comes in every time, as it affects the sludge exactly the same way, the odours are the same, those types of indications,’ he said.
But the Water Authority is still in the dark about what’s causing the problems.
‘All we know is that a highly toxic chemical able to kill the bacteria in seven million gallons of sewage entered the collection system somewhere on Seven Mile Beach,’ said Mr. Todaro.
‘It has to be either a large volume, or a smaller volume of something extremely toxic. It could be coming from a private residence, it could be coming from a hotel, or a cleaning company that’s doing supermarkets, a dry cleaner, or a photo printing shop,’ he said.
In an effort to get to the bottom of the mystery, Water Authority staff have tested about twenty different chemical samples collected from cleaning companies, hotels, and laundries, with little success.
‘We’ve got people still trying to figure out what is going on but the manpower here is limited – we have only two lab workers at the sewage plant, and the main lab doesn’t have the $10-million equipment to identify the chemicals so we would need to send samples off-Island for testing,’ said Mr. Todaro.
He hopes the incidents will highlight the need for heightened environmental awareness and enforcement of anti-dumping regulations.
Currently, under Section 47 of the Water Authority Law, improperly disposing of septic tank waste carries a fine of up to $10,000 and imprisonment for 12 months.
Under Section 48, persons emptying matter likely to damage the sewer system, or disposing chemical refuse, chemicals, acid, petrol or flammable liquids into the sewer system face a fine of $10,500 and an additional $500 a day for every day the activity continues after notification by the Water Authority.
At the same time, Mr. Todaro says that there are few options for companies and individuals to safely dispose of used chemicals.
‘For instance, we have people coming here all the time with septic trucks containing petroleum products and pumping them into our system. There’s not enough manpower to monitor everything,’ says Mr. Todaro.
‘It’s a Catch-22 when you put in a sophisticated treatment system and you are challenged with keeping it operable and you can’t enforce what people are putting into it. Luckily we don’t have any industry hooked up to this sewage plant – then we would really have a serious problem.’
The plant, which typically treats 1.8 million gallons of sewage a day, usually has about seven million gallons of sewage in its tanks at one time.
The process is a well choreographed ballet of pumps, tanks and valves that depends on a sophisticated computer system and a certain level of water quality that’s relatively free of oils and harsh chemicals.
Raw sewage originating from the Water Authority’s sewer customers along the Seven Mile Beach corridor is pumped into the plant, cleared of debris, oils, sand and silt, then transferred to another tank where special bacteria work in tandem with oxygen to attack pollutants in the water.
After about four hours, the bacteria-containing sludge sinks to the bottom of the vast tank, and the clear water on top is sluiced off and injected into deep wells, eventually filtering through the bedrock to the water table.
The remaining sludge either remains in the tank for reuse, or is pumped to storage lagoons to settle further and await proper disposal.