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Position on the enforcement of Canada-wide standards regarding municipal sewer system overflows

Ministerial Position

Updated December 4th, 2014

For more information:

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.


Ministerial Position

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:

  • An electronic event recorder;
  • A floating materials retention device, unless it has been demonstrated that installing such a device is not possible or that it could cause back-ups in buildings. A simple barrier holding back objects that float to the water’s surface prior to the overflow may be acceptable as a floating materials retention device.

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.

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Documents to submit to the Department (MDDELCC)

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:

  • The municipality’s commitment, by resolution of the council, to install electronic equipment to record overflow events in the overflow structures that are not already equipped with it and that are affected by the project and where at least one overflow event during periods of rain or thaw has been recorded in the previous three years;
  • The municipality’s commitment, by resolution of the council, to add floating materials retention devices to the overflow structures that are not already equipped with such devices and that are affected by the project and where at least one overflow event during periods of rain or thaw has been recorded in the past three years, unless it has been demonstrated that installing such a device is not possible or that it could cause back-ups in buildings;
  • A report signed by an engineer demonstrating that the proposed compensation measures ensure that, after the project’s completion, rainfall episodes will not result in an increase in the frequency of overflows (or the overflow volume or time). A modeling of the sewer system and simulation of the system’s performance during reference rainfall (for example, corresponding to the frequency of overflows observed) before and after the project’s completion can be used to demonstrate this. In such instances, the calculation assumptions used for the simulations must be clearly established and realistic;
  • Drawings and specifications make it possible to carry out compensation measures. These measures should normally be undertaken in conjunction with the proposed project. In cases where the compensation measures cannot be carried out in conjunction with the proposed project, the authorization request must include the municipality’s commitment, by resolution of the council, to perform the work required within the proposed timeframe. Before the MDDEFP can authorize a new project on the territory of a municipality, the municipality must demonstrate that the previously planned compensation measures have been carried out or that they are provided for in the new authorization request. Lacking that demonstration, the request will be denied. A municipality can also reach an agreement with the MDDEFP to group several projects together and plan global compensation measures to be carried out within a given timeframe.

(1) Except for projects of less than 10 m3/day, expressed in average flow rate, if the sewer system meets its overflow requirements.

 


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