Capacity for sending natural gas from Alberta and British Columbia (BC) east across the continent will jump by 280 MMcf/d by November 2021, TransCanada Corp. announced Monday.

Shippers triggered a C$140 million (US$105.9 million) expansion to the exit from TransCanada’s western supply collection network onto its cross-country Mainline by signing new service contracts lasting an average 22 years.

The project, at the junction of the Nova Gas Transmission Ltd. (NGTL) grid and the Mainline’s entrance in southeastern Alberta at Empress, is part of a C$7.3 billion (US$5.52 billion), multi-year series of facilities additions.

The current edition of TransCanada’s annual five-year capital plan for NGTL predicts traffic will grow to 7 Bcf/d onto the Mainline, which serves cross-border links into the United States as well as eastern Canada.

The eastbound volume projection is up by about 40% from previous pessimistic forecasts that Mainline traffic would continue to stagnate at a depressed level of 4.9 Bcf/d, saddling the pipeline and shippers with expensive excess capacity.

The lion’s share of additions to NGTL caters to development of high-volume, low-cost production in the Montney and Duvernay shale formations in the Peace River region of northern BC and Alberta. The capital plan predicts 85% of natural gas flowing in the NGTL web will soon come from the shale deposits straddling the two provinces.

A preliminary project description for NGTL expansion by late 2021, filed at the National Energy Board, calls for installing 350 kilometers (217 miles) of jumbo pipe 48 inches in diameter to handle an additional 1.1 Bcf/d flowing across the Alberta and BC grid. Increasing natural gas flows are expected to go to Alberta thermal oil sands plants as well as eastern Canadian and U.S. markets.