REGINA — The city of Regina made a miscalculation into how much partially treated sewage water was actually released into Wascana Creek two weeks ago after heavy rain.
An initial figure of one million litres was given, but on Monday, Pat Wilson, the city’s director of water works, explained that the amount is is closer to 15 million litres.
Wilson explained the earlier figure was based on retention volumes of the wet well at the McCarthy Boulevard pumping station.
She says the new calculation was done using pump rates and the amount the bypass valve was open.
Wilson said while most of Regina received roughly 78 millimetres of rain in a 24-hour period on July 27, the northwest got pelted with anywhere between 90 and 107 millimetres.
To save infrastructure from getting damaged and to prevent homes from getting sewer backup, a decision was made to bypass most of the usual wastewater treatment process and instead, release screened sewage mixed with rain water directly into the creek.
“A bypass is never a desirable event,” she said.
Within a few days of the release, Wilson said the creek returned to its condition before the release.
“The diversion did not have a lasting impact on the creek water quality.”
The city says investments and improvements are being made to the pumping station to ensure capacity is increased so that the system can handle significant future rainfall events.