What will be the effect of the heated chlorinated discharge on surrounding marine life and ecosystems?

Updated – January 2017: In October 2016, Squamish Nation Chiefs and Council voted to select air cooling as the cooling technique Woodfibre LNG Limited will use to cool its LNG facility. Find out more: woodfibrelng.ca/squamish-nation-announces-decision-on-woodfibre-lng-plant-cooling-technology/.

Thank you for your question Jordan.

Woodfibre LNG’s seawater cooling system is being designed to minimize the potential effects on marine water quality and on marine plants and animals.  This includes meeting Canadian legislation (e.g. Fisheries Act) and Fisheries and Ocean’s Canada best management practices.

Seawater will be discharged to Howe Sound through an outlet pipe and a diffuser system at a depth of more than 25 m, which is below the depth where marine organisms are found in the greatest numbers.

The diffuser will include ports along its length to promote mixing of the seawater with the water around it, which helps reduce the volume of warmed water.

The temperature of the seawater will be less than 21°C, or 10°C above the water temperature of Howe Sound, whichever is less.

Because of the diffuser design and dissipation of heat, the total volume of water with a temperature between 1°C and 10°C above the surrounding water is expected to be less than 125 cubic metres (approximately 1/20th the volume of an Olympic-size pool). This volume will not increase over time.

Residual levels of chlorine at the discharge ports will be less than 0.02 mg/L. This is much less than the chlorine in drinking water, which is approximately 0.04 mg/L to 2.0 mg/L.

The levels of residual chlorine will be closely monitored.
Before being discharged back into Howe Sound, the seawater will pass through a de-aeration tank. This tank is designed to encourage mixing of seawater and the air, which removes chlorine from the water.

If needed, a de-chlorination agent will be added to the seawater to reduce the chlorine concentration to meet water quality guidelines.

For additional information see Section 5.10 Marine Water Quality, Section 5.16 Marine Benthic Habitat, and Section 5.18 Forage Fish and Other Fish (Marine) of our Environmental Assessment Certificate application.