Tallgrass Energy Partners LP said Monday that FERC has approved its Zone 3 East-to-West Project that would modify the Rockies Express Pipeline (REX) to send an additional 1.2 Bcf/d of Appalachian natural gas to Midwest markets.

REX is now waiting for the Federal Energy Regulatory Commission (FERC) to issue a final Notice to Proceed, and the project is expected to be in service in the second half of the year. The pipeline’s Seneca Lateral, which delivers 600 MMcf/d from MarkWest Energy Partners LP’s Seneca gas processing plant in Noble County, OH, to the Rex mainline and westward through Ohio, Indiana and Illinois is already in service (see Shale Daily, June 18, 2014) . Tallgrass, which operates and owns half the pipeline along with Sempra U.S. Gas & Power (25%) and Phillips 66 (25%,) said Monday that the lateral has reached full capacity.

Rex said in its FERC application that adding the Zone 3 capacity would require modification of certain delivery interconnects and the construction of two others along with compressor stations (see Shale Daily, June 24, 2014). The 1.2 Bcf/d is fully contracted for average terms of 20 years.

The additional capacity is being added to move Appalachian gas from the Clarington Hub in Monroe County, OH, to an interconnect with Natural Gas Pipeline Co. of America in Moultrie County, IL.

Rex also said Monday that it would launch a binding open season for up to an additional 800 MMcf/d of east-to-west capacity on Zone 3, which it said would require no new pipeline, but rather three new compressor stations and modifications to existing pipeline facilities. That project has already received 700 MMcf/d in binding precedent agreements. It is currently expected to be in service by the second half of 2016 and it would give some parts of the system up to 2.6 Bcf/d of east-to-west capacity.