Continuing investigations in to the safety of BC Hydro’s Coquitlam dam in Canada has required maintaining the reservoir at its current level of 149m, until the necessary dam improvements have been implemented. The current investigations have focussed on the response of the existing dam to earthquake loading.

As part of BC Hydro’s ongoing dam safety programme, all the company’s dams are examined regularly to ensure they meet current earthquake standards. Recent investigations have confirmed the existence of a loose zone within the Coquitlam dam. Indications are that this zone could liquefy during a moderate or large earthquake causing unacceptable deformations in the dam.

Maintaining the reservoir at the maximum level of 149m has been determined to be safe, even for the maximum credible earthquake. The utility expects that it may take one to two years to complete the engineering analysis after which the dam upgrade work can be undertaken.

Coquitlam dam, on the Coquitlam river – a tributary of the Fraser river – was built in the early 1900s by the hydraulic fill method. The dam is a 366m long earth and rockfill embankment dam with a maximum height of approximately 30.5m.

…while first Meridian study gets under way

The provincial Governments of Alberta and Saskatchewan in Canada are studying the implications of constructing a storage dam on the border between the two provinces.

The dam, referred to as the Meridian dam, is to be located on the South Saskatchewan river on Alberta’s eastern border with Sakatchewan. The dam is expected to create a reservoir in the South Saskatchewan river valley that would extend upstream to almost the city of Medicine Hat.

The preliminary engineering study, costing about US$65,934, is expected to be completed by the end of the year. During the assessment, all environmental issues that could arise due to dam construction will be identified.

A dam and reservoir concept for the South Saskatchewan river was envisioned as far back as 1920. Proponents of the dam say it will provide hydro power, as well as opportunities for water based recreational benefits.