With or without Sewergate. there continues to be a large quantity of untreated or partially treated waste flowing from the Hamilton sewer system into the Bay. To put it in perspective, in the four years since the so-called Sewergate incident the city has averaged 2.3 billion litres of sewage flowing into the bay per year in what are termed bypass events. That is about 40 percent of what was flowing into the bay in the four and a half years when the undetected sewage spill was happening. Bypass events occur during heavy downpours when the system, including a network of holding tanks, is overwhelmed by the volume of rain and the mixture of rainwater and sewage flows untreated or partially treated into the Bay. Hamilton like many cities has part of its sewer system separated-where rain water and sewage are separate; but in older parts of the city, both flow through the same set of pipes.
A staff report to the Hamilton Public Works Committee says even when bypass events become necessary it is usually possible to provide a reduced level of treatment. The report says when the current upgrade program at the Woodward Avenue Wastewater Treatment Plant is complete later this year the system will have greater capacity. Hamilton and Kingston are the only cities in Ontario that provide real-time reporting of bypass events, which can be accessed by this link.