Kinder Morgan Canada announced Thursday it is planning an even bigger expansion of its Trans Mountain pipeline that could see oil tanker traffic in Vancouver’s harbour increase from five to 34 vessels per month. The original plan called for up to 25 tankers visiting the port monthly.

The company has signed additional long-term contracts with major oilsands producers and shippers totalling 700,000 daily barrels, so the planned pipeline capacity will be raised from 750,000 to 890,000 barrels. The pipeline currently carries up to 300,000 barrels per day.

“We’re seeing growing interest, and in some cases concern and angst, from producers around their ability to access markets with growing production,” said Kinder Morgan Canada president Ian Anderson when asked if the new contracts were due to growing concerns Enbridge’s proposed Northern Gateway pipeline won’t be approved.

“We are seeing more support and interest in our project. I wouldn’t connect that interest directly with Northern Gateway’s prospects, but I think more generally to the need to access markets for Canadian production,” he said.

The announcement heightens concerns over a worst-case oil spill, Vancouver Mayor Gregor Robertson said in a statement.

“Any serious spill would jeopardize tens of thousands of jobs and could leave taxpayers on the hook for billions of dollars in clean-up costs and losses.”

Leaders of the Tsleil-Waututh Nation said they were disappointed but not surprised by the announcement.

“This shows that there is no limit to what Kinder Morgan will push for,” said Chief Justin George in a statement. “Citizens need to ask some serious questions of their leaders before this pipeline is approved.”