Re: “Diluted bitumen won’t sink: Enbridge,” Feb. 7.

An Enbridge technical report states that the diluted bitumen would have a density of 1.01 and so would float on undiluted seawater with a density of 1.025. However, Douglas Channel is headed by an estuary with fresh water (density of 1.0) and brackish water floating out over the surface. Where the water density is less than 1.01, the diluted bitumen would sink at least several meters, blanketing the bottom.

Sinking might also result from evaporation of the lighter fraction, and from being broken up by dispersants if these were used. This was suggested to explain the plumes of oil on the sea bottom during the British Petroleum spill in the Gulf of Mexico.

Surveys of bottom life conducted for Enbridge are limited to the area around the Kitimat Terminal. The remaining 180 kilometres of shoreline remains unassessed. I gave the Joint Review Panel a synopsis of a quick survey I did in 1992 near the entrance of the tanker route. There were at least 92 species among 12 groups of marine seaweeds and invertebrates.

Given the limited information on life along the bottom and edges of this fjord, how can we address key questions on the potential impacts of bitumen on this life?

Bill Austin

North Saanich

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