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Dams and Hydrology

Measures provided by the Dam Safety Act and Regulation

Note: This table outlines the main provisions. The Regulation published in the Gazette officielle du Québec is the only official text.

Summary of main provisions :


High-capacity dams: summary of main provisions

 

Reference

Summary of main provisions

Act

Regu-
lation

Existing dam

Sec. 37

Sec. 4

  • Dam completely constructed by the date of coming into force of the Act;
  • Dam under construction by the date of coming into force of the Act;
  • Dam construction project for which the developer had, on the date of coming into force of the Act, the required approval under the Watercourses Act (R.S.Q., c. R-13).
Classification

Sec. 14

Sec. 9 to 19

Every dam is classified on the basis of its vulnerability and the consequences of its failure. There are five classes: A, B, C, D and E. Class A dams are usually larger dams with higher failure consequences.

Only the dams in the Very Low Consequence category can be a Class E dam.

A dam owner may request a review of the classification of the dam if a report made under the responsibility of an engineer is submitted with the request.

Failure consequence category

Sec. 14

Sec. 16 to 19

The dam failure consequence category must be determined, as the case may be, by means of a dam failure analysis, rough mapping of the inundated area or characterization of the area affected by the failure. There are six consequence categories: Very Low, Low, Moderate, High, Very High and Severe.

The consequence category shall be determined or reviewed prior to authorization for construction, structural alteration, change in use or stopping of the operation of a dam and following a dam safety review.

Sec. 74 (2)

On the date of coming into force of the Act, the Minister assigns a consequence category to every dam.

Minimum safety standards

Sec. 15

Sec. 20 and 21

Floods: - the characteristics of a dam must ensure resistance to no less than the safety check flood corresponding to its failure consequence category:
  • Very Low or Low Consequence Category: Ô Safety check flood = 1 : 100 years;
  • Moderate or High Consequence Category: Ô Safety check flood = 1 : 1000 years;
  • Very High Consequence Category:  Ô Safety check flood = 1 : 10 000 years or ½ PMF;
  • Severe Consequence Category: Ô Safety check flood = Probable maximum flood (PMF).

Sec. 22

  • for a dam of which at least 50% of the inflow is controlled by one or more upstream dams, the safety check flood shall take into account the discharge capacity of the upstream dam;

Sec. 23

  • the safety check flood may be less for a given dam if an analysis of the flows for lesser floods shows that a failure during such floods would not cause incremental damages, that is when the rise in the water level caused by the failure does not exceed 60 centimetres or when the incremental damages attributable to the dam failure are not higher than those considered in the Low Consequence Category;

Sec. 24

  • only one safety check flood shall apply to all the dams located on the rim of a single reservoir and it shall be that of the dam with the highest safety check flood;

Sec. 25

  • the crest of an erodible dam, except for Severe Consequence Category dams, must not be less than 1.0 metre above the safety check flood level, unless the owner demonstrates that all hydrologic and hydraulic uncertainties have been taken into account.

Sec. 28 and 29

Earthquakes: dams must be designed to remain stable during the earthquake loading to which it may be subjected. A map of the seismic zones is appended to the regulation. It includes the seismic factors to be applied in the assessment of the dam stability in earthquake conditions.

Sec. 75

Those safety standards (floods and earthquakes) must be applied to new dams from the date of coming into force of the Act. For existing dams, they must be applied following the dam safety review or when a structural alteration requiring an authorization is performed if that alteration occurs before the first safety review.

Impounded water management plan

Sec. 19

Sec. 30 to 34

An impounded water management plan must be drawn up by an engineer for every dam except class E dams.

This plan shall describe all the procedures to be followed by the owner for the safe management of the impounded water, in particular during situations in which persons or property are at risk.

It must include, among other things, the full supply level, the level of the safety check flood, the discharge curve, a description of the measures that will be taken by the owner to manage the reservoir and, where appropriate, a description of the communications strategy for providing information on potential hazards to the people affected and to the civil protection authorities.

This plan must be kept up to date and a summary forwarded to the local municipality in which the dam is located. It must be drawn up before the commissioning of a dam.

Sec. 76

For an existing dam, the impounded water management plan must be drawn up at the date the first dam safety review shall be conducted or prior to authorization for structural alteration, change in use or stopping of the operation of the dam.

Emergency action plan

Sec. 19

Sec. 35 to 40

An emergency action plan is required for every Moderate, High, Very High and Severe Consequence Category dam.

This plan sets out the procedures to be followed for the protection of persons and property upstream or downstream of the dam in the event of an actual or imminent dam failure or to mitigate the effects of the disaster. It must include, among other things, a list of the conditions that could lead to a dam failure, a general description of the area that would be inundated, the warning procedures and inundation maps.

This plan must be kept up to date and a summary forwarded to the local municipality in which the dam is located. It must be drawn up before the commissioning of a dam.

Sec. 77

For an existing dam, a preliminary plan must be prepared within 1 year of the coming into force of the Act and a final plan prepared at the date the first dam safety review shall be conducted or prior to authorization for structural alteration, change in use or stopping of the operation of the dam.

Monitoring

Sec. 20

Sec. 41 to 45

Every dam must be monitored. Three types of monitoring activities are fixed in the draft regulation:

  • Site inspections (routine visual inspection to detect the more apparent deficiencies): frequency varies from once a month for Class A dams to once a year for Class E dams. Site inspections of Class A and Class B dams shall be carried out under the supervision of a civil-engineering technician or an engineer.
  • Regular inspections (visual examinations of the dams and its main components): frequency varies from 4 times a year for a Class A dam to once a year for a Class D dam. No regular inspection is required for Class E dams. Regular inspections of Class A and Class B dams shall be carried out by a civil-engineering technician under the supervision of an engineer. Regular inspections of Class C and Class D dams shall be carried out by a civil-engineering technician or by a person familiar with the dam under the supervision of a civil-engineering technician or an engineer.
  • Formal inspections (comprehensive visual examinations of each component of the dam): frequency varies from once a year for Class A dams to once every five years for Class D and Class E dams. This inspection must be carried out by an engineer.

This provision applies to every dam from the date of the coming into force of the Act.

Dam logbook

Sec. 21

Sec. 46 and 47

Every dam owner shall establish and maintain a logbook in which activities (such as maintenance and inspections) and important events relating to dam safety (such as floods and earthquakes) are recorded.

This provision applies to every dam from the date of the coming into force of the Act.

Dam safety review

Sec. 16 and 17

Sec. 48 to 52

At regular intervals, every dam must undergo a safety review by an engineer. The purpose of this review is to evaluate the safety, stability and functionality of the dam, the conformity of its design and construction with good practice and safety standards and to determine appropriate remedial measures. The safety review must be conducted no later than 10 years after the commissioning of the dam and updated at least every 10 years.

 

Sec. 78

The first safety review for existing dams shall be conducted within the time limit indicated below:

  • 3 years after the coming into force of the Act for Very High and Severe Consequence dams;
  • 5 years after the coming into force of the Act for Moderate and High Consequence dams;
  • 7 years after the coming into force of the Act for Low Consequence dams;
  • 9 years after the coming into force of the Act for Very Low Consequence dams.

If the condition of an existing dam is Good and the reliability of its discharge facilities rated Acceptable, the owner may add 1 year to the time limit indicated above.

Safety program

Sec. 23 to 27

Sec. 53 to 56

Dam owners who developed and implemented their own safety program may submit that program to the Minister. If approved, it will replace some safety standards.

Admissibility criteria: 

  • the owner owns at least 10 dams;
  • the program has been in effect, under the responsibility of qualified persons, for at least 5 years;
  • the program covers all the dams belonging to the owner.

A program includes provisions relating to impounded water management, emergency preparedness, monitoring, dam safety review, maintenance, logbook and persons in charge of its implementation.

Authorization

Sec. 5 to 9

 

By the date of coming into force of the Act, the construction, the structural alteration, a change in use likely to affect dam safety, the removal and the permanent or temporary stopping of the operation of a dam shall be authorized by the Minister.

Sec. 10

Sec. 57 to 63

The plans and specifications for the project, prepared by an engineer, must be submitted with the applications for authorization for the construction and structural alteration of a dam. A Certification of compliance (Format PDF  Word file, 220 Ko, french), also prepared by an engineer, that the work has been carried out in conformity with the plans and specifications and any conditions of authorization shall also be submitted to the Minister upon completion of the work. Moreover, depending on the purpose of the authorization, hydrologic and hydraulic studies and stability studies shall be submitted with applications.

Processing fees*

Sec. 36 (4)

Sec. 64

Authorization relating to the construction or structural alteration of a dam: depending on the cost of the work requiring authorization (minimum $1000)

Sec. 65

Authorization for a change in use or a stopping of the operation of a dam: $214

Sec. 66

Authorization for removal of a dam: Class A dams: $1068, Class B dams: $534, Class C, D or E dams: $266

Sec. 67

Approval of remedial measures following a safety review: Class A dams: $4269, Class B dams: $2669, Class C, D or E dams: $1068

Sec. 68

Approval of a safety program: $10,673

Annual fee*

Sec. 36 (5)

Sec. 69

Class A and B dams: $908

Class C and D dams: $187

Class E dams: $107

* Certain fees shall be ajusted April 1 of each year according to changes in consumer prices.

Low-capacity dams : summary of main provisions

 

Reference

Summary of main provisions

Act

Regu-
lation

Declaration

Sec. 29

 

By the date of coming into force of the Act, a declaration must be filed with the Minister of the Environment by the promoter or owner of every low-capacity dam for the construction, structural alteration and removal of a dam.

Sec. 72 and 73

The declaration includes a description of the project. The plans and specification drawn up by an engineer must also be submitted with the declaration, except in the case of the removal of a dam.

 

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© Gouvernement du Québec, 2003