Calgary-based Inter Pipeline Ltd. says it will spend $1.35 billion to buy the Canadian oil and gas assets of the Williams pipeline companies.

Williams' infrastructure in Alberta include two plants near Fort McMurray that extract natural gas liquids, a gas processing plant near Redwater, and a 420-kilometre pipeline system connecting the two.

Oklahoma-based Williams says it spent about $2.5 billion on the development of its Canadian business over 16 years.

In the deal, Calgary-based Inter Pipeline (IPL.TO) will also acquire a proposed $1.85-billion facility near Redwater that is designed to turn propane into propylene pellets used in plastics manufacturing.

The company says it expects the facility will qualify under the Alberta government's petrochemical diversification program that offers up to $500 million in royalty credits for value-added projects.

Inter Pipeline says it plans to make a decision by the end of the year on whether to go ahead with the facility, which Williams has already spent $250 million developing.

Williams reported a net loss of US$405 million in the last quarter, blaming it largely on a US$747 million impairment charge related to the pending sale of its Canadian operations.