The Unit 4 project, which was completed $8M under its $96.8M budget and five days ahead of the accelerated in service date of 30 April, will increase the output at Seven Mile by 302GWh annually, which is enough energy to power over 30,000 homes in British Columbia, Canada, each year.

‘Our objective was to have Unit 4 in service before the start of the spring run-off, allowing BC Hydro to maximise electricity production from flows on the Pend d’Oreille river, and that has been achieved,’ said Seven Mile Maintenance & Operations Services manager, Mark Poweska.

Following environmental approval in 1996, the provincial government and BC Hydro’s board gave approval for construction of Unit 4 in January 2001 as part of the Resource Smart programme. Like BC Hydro’s Power Smart programme, the goal of Resource Smart is to identify and implement efficiency gains at existing facilities. The project also included installation of replacement switchgear for Unit 3.

Seven Mile Unit 4 will also help reduce BC Hydro’s total greenhouse gas emissions by an estimated 170,000 tonnes each year as it displaces the need for gas-fired generation elsewhere in the system.

Seven Mile generating station began producing electricity in 1979, and was built to house four generating units. By 1981, three units were in service with plans for Unit 4 deferred until provincial energy needs warranted its installation. The addition of Unit 4 makes Seven Mile the fourth largest plant in the BC Hydro system, with a total generating capacity of 804MW, or about 8% of all hydroelectric capacity.