Belleville’s pollution control plant is on track to recording fewer secondary bypasses of sewage into the Bay of Quinte.

Brad Wilson, the city’s director of environmental and operational services, said there have been three secondary bypasses done since the start of the year, puts the plant on track to recording fewer than the average 11 to 13 bypasses usually done on a annual basis.

The first secondary bypass was done Jan. 25 to 26, which was followed by another on March 14 and 15. The third happened on June 24 and 25.

“They’re all of a result of heavy precipitation,” he said. “Three up to now is probably less than a normal year. It’s been a little easier to cope.”

Wilson said on those three occasions the sewage bypasses secondary treatment but still undergoes primary and tertiary treatment.

At the primary stage, the plant’s screening system removes all large particles from the sewage.

“It scrapes off the big stuff and doesn’t allow it through the plant and back into the bay,” he said.

During tertiary treatment, the flow of water and sewage is given a blast of chlorine to lower its ability to cause harm to the bay.

“What’s being placed into the bay is not untreated sewage,” he said.

Wilson said bypasses are done when the sewage treatment system is overwhelmed by a heavy downpour of rain. He said when that happens the plant is unable to handle the sudden rush of water, so it is allowed to only go through certain parts of the system.

“There is too much water and that part of the process can’t handle the flows,” he said. “That would put an excessive load on our sewer treatment plant and sometimes cause the sewage treatment plant to have to go into bypass.”

He said heavy rainfall also disrupts other maintenance activity, such as clearing debris from storm sewers.

“There are times when we do get heavy rains and it can affect a lot of things from the storm sewers to the sanitary sewers,” he said.

Wilson said city staff are available on call 24 hours a day to deal with emergency situations such as flooding or sewer backups. He said when a bypass is done the sewage only “goes through a portion of the plant.”

He said the sewage is also diluted with the heavy flow of storm water before it hits the bay. He said the bypass is done to meet all safety standards before the water is flushed into the bay.

He said there is an extensive procedure that has to be followed, which includes notifying the Ministry of the Environment when a bypass done.

To alleviate the flooding problem that could arise, city staff are constantly removing storm water from the sanitary sewers through various capital works projects, Wilson said.

He said there often times typical flooding that results from the storm sewers being surcharged or blocked by debris is dealt with by dispatching staff.

“They respond to any complaints from the general public,” he said.

via Fewer sewage bypasses in 2010 – Belleville Intelligencer – Ontario, CA.