Dam Safety Scheme established

On 7 July 2008 the Building (Dam Safety) Regulations 2008 were established, ushering in a 24-month transitional period before the scheme comes into force. 

Dam safety has been a concern for a number of years. This was brought to a head by the Opuha Dam in South Canterbury failing during construction in 1997 and various flood events around the country during the late 1990s.

Historically, unlike many other countries, New Zealand has not had a regulatory risk-management system in place. However, once constructed and commissioned, dams need ongoing monitoring, maintenance and repair in order to maintain their integrity.

A more structured and formal system of compliance monitoring will ensure the safety of dams, taking into account the changing nature of public ownership and commercial arrangements for owning, operating and managing dams.

New Zealand has about 1150 large dams that, until now, have not been subject to a formal system of dam monitoring, inspection and maintenance. The potential impact of a dam’s failure can change over time due to factors such as site conditions, hazards such as flood events or earthquakes, and the effectiveness of maintenance.  Accordingly, the Dam Safety Scheme has been introduced to ensure that from 1 July 2010 all large dams are regularly monitored, and the risk to people and property is minimised.

The Regulations apply to large dams that are capable of holding a reservoir of 20,000m3 or more (about the size of eight Olympic-sized swimming pools) and of retaining three or more metres’ depth of water or other fluid. This is classified as a large dam in terms of the Act and means it has to comply with the Dam Safety Scheme.  The definition also applies to dams that only rarely hold and retain these amounts and depths of water or other fluid. The definition includes flood detention dams but excludes stopbanks.

The Dam Safety Scheme requires the owners of a large dam to:

• assess whether their dam is affected by the scheme (ie, meets the size/volume threshold - basically the equivalent of a rugby field filled with water up to the goalposts)
• classify the dam as having low, medium or high potential impact (on people, property and the environment in the downstream area if the dam were to fail)
• get the dam classification certified by a recognised engineer, and
• register the dam and submit its classification with the appropriate regional authority (within three months of the 1 July 2010 commencement date of the Scheme or within three months of their dam being commissioned).

For dams classified as having a medium and high potential impact the dam owner must:

• prepare and submit a Dam Safety Assurance Programme (which includes surveillance and maintenance procedures) to the regional authority, within one year if a high potential impact dam, and two years if a medium potential impact category dam
• provide evidence that all procedures in the Dam Safety Assurance Programme have been complied with by submitting an annual Dam Compliance Certificate to the regional authority, and
• ensure the Dam Safety Assurance Programme and annual Dam Compliance Certificate are audited and certified by a recognised engineer.
• Regional authorities will compile and maintain a register of dams.

Smaller dams are not affected by the dam safety scheme, although they still need to comply with the Building Act 2004 in terms of meeting the Building Code standards, etc.

 Meridian Energy’s Benmore Dam

If you have any queries relating to the Dam Safety Scheme, please contact:

Hassan el Maaroufi
Advisor, Operational Policy
Department of Building and Housing
DDI +64 4 496 4732
Fax +64 4 494 0290
Email: info@dbh.govt.nz