Combined Sewer Overflow

In wet weather, combined sewers overflow into nearby receiving waters, where they cause pollution. To lessen this pollution, various measures have been developed, including storage of overflows in tanks and subsequent treatment at a central wastewater treatment plant. The older combined sewer overflow tanks may be undersized, however, and can overflow, while providing only limited treatment (by settling) of the CSOs passing through these tanks. The effectiveness of existing combined sewer overflow facilities needs improvement. Environment Canada has been supporting remediation of pollution in the Areas of Concern in the Great Lakes Basin . This particular study has been done by NWRI in support of the Toronto Waterfront Remedial Action Plan.