Position on the enforcement of Canada-wide standards regarding municipal sewer system overflows
Updated December 4th, 2014
On February 17, 2009, the Canadian Council of Ministers of the Environment (CCME) adopted the Canada-wide Strategy for the Management of Municipal Wastewater Effluent. Although Québec has not yet formally signed on to the strategy, it has declared its support of the strategy’s technical content and wishes to ensure that the criteria for land development or redevelopment projects minimally integrate the Canada-wide overflow standards established by the Strategy.
As of April 1, 2014, any sewer system extension project likely to increase the frequency of combined, sanitary or pseudo-sanitary sewer overflows will not be authorized.
Any diversion of wastewater to a sewage treatment facility during periods of rain or thaw is deemed to be an overflow.
This procedure also applies to any increase in flow in the sewer system resulting from the redevelopment of a sector or from an industry’s installation, enlargement or increase in production.
This rule does not, however, apply to projects of less than 10 m3/day, expressed in average flow rate, if the existing sewer system meets its overflow requirements.
The Ministère du Développement durable, de l’Environnement et de la Lutte contre les changements climatiques (MDDELCC) considers that any addition of flow in combined, sanitary or pseudo-sanitary sewer networks that experience overflows during periods of rain or thaw is likely to increase the frequency of these overflows. Consequently, any development or redevelopment project must include compensation measures to avoid increasing the frequency of overflows. It is up to the design engineer to demonstrate that, when the compensation measures are taken into account, the proposed development or redevelopment will not result in an increase in overflow in the overflow structures located downstream from the connection point, or an increase in diversions to the wastewater treatment plant.
It is important to clarify that the ban on increasing overflow frequency applies even if the limit set by the existing overflow requirement has not yet been reached. If an overflow requirement is not currently being enforced downstream of the project, corrective measures must be put in place to meet compliance. If failure to comply with overflow requirements is simply due to a change in the type of measuring equipment (e.g.: block identifier replaced by electronic equipment), the facility is considered to be in compliance with its overflow requirements as long as this is confirmed by a correlation of data.
In some cases, the water overflow volume or overflow time could be controlled instead of the overflow frequency.
For a development or redevelopment project to be authorized, the overflow structures downstream where at least one overflow event during periods of rain or thaw has been recorded in the past three years must be equipped with:
If the municipality does not have this equipment, it must, when filing its request for authorization, commit to install it.
Projects to extend sewer systems into combined systems will not be authorized unless it can be demonstrated that it is impossible, even in the long term, to channel rainwater to a separate rainwater drainage system or to a water surface. Since the ban on increasing the overflow frequency applies even in these cases, it is to be expected that significant compensation measures will be required to avoid an increase in the overflow frequency.
No overflow points will be authorized, with the exception of an emergency overflow. However, an existing outlet that is intercepted to channel water to a treatment plant can result in the addition of a new overflow point that may be authorized.
As of April 1, 2014, in addition to the authorization request form for carrying out a waterworks and sewer project and the corresponding attachments, the following documents must be provided with the authorization request for all projects to extend sanitary or combined sewer systems1, or for any project that could result in an increase in the overflow frequency in overflow structures located downstream: