Williams Cos. announced an open season from Sept. 3 to Sept. 29 for the Western Marcellus Pipeline project, which is an expansion of the Transco interstate pipeline. Transco is a wholly owned subsidiary of Williams Partners LP, of which Williams owns controlling interests and is the general partner.

The Western Marcellus Pipeline project is being designed to provide from 1 billion to more than 2 billion cubic feet per day of new natural gas transport capacity. The project would allow for gas transport from receipt points in the western Marcellus and Utica areas to destinations as far south as Transco’s Zone 3 compressor station 65 in Mississippi and as far north as the proposed Zone 6 River Road point in Pennsylvania. The project would connect the company’s Ohio Valley Midstream processing and gathering system in northern West Virginia with the Transco Pipeline.

The project’s design consists of a greenfield pipeline from the Rockies Express Pipeline near Clarington, Ohio, and Williams Oak Grove processing plant in Marshall County, W.Va., to Transco compressor station 165 in southern Virginia. From there, mainline modifications would allow both northbound flow to the River Road point and southbound flow to Station 65 for much of the project capacity.

The results of the open season will determine the final capacity, scope and cost of the project. It will also be subject to approval by the Federal Energy Regulatory Commission and other agencies.