By Brenna Owen The British Columbia government says a decade-old environmental assessment certificate remains valid for the construction of a natural gas pipeline in northern B.C., in a decision opposed by the province’s Green Party and environmental groups. The Environmental Assessment Office says it has determined the Prince Rupert Gas Transmission pipeline has “substantially started,” fulfilling a requirement of the 2014 certificate and allowing the project to proceed without a new assessment. The original approval was for a roughly 900-kilometre pipeline between Hudson’s Hope in northeastern B.C. and Lelu Island near Prince Rupert, the site of a liquefied natural gas processing facility that has since been cancelled. The pipeline was purchased by the Nisga’a Nation and Texas-based Western LNG last year to supply natural gas to the proposed Ksi Lisims…