Williams Partners LP said Tuesday it has placed into service the first phase of its Hillabee Expansion, adding 818,410 Dth/d of capacity in Alabama to its Transcontinental Gas Pipe Line (Transco) system.

The new capacity would be used to supply Transco Zone 4 gas to serve Florida power generators via the Sabal Trail Pipeline, which has been in service since mid-June. In total, the Hillabee expansion, planned to come online in three phases, would add nearly 1.132 million Dth/d to Transco by 2021.

“The Hillabee project is an important Transco expansion, providing clean-burning natural gas to meet the needs of Florida’s rapidly growing power generation market,” said Williams’ Frank Ferazzi, senior vice president of the Atlantic-Gulf operating area. “Together, the Hillabee and Sabal Trail projects connect Florida power generators with Transco’s Station 85 Pool, giving them direct access to robust natural gas supply basins in the Haynesville and Midcontinent area, and soon with the completion of Atlantic Sunrise, to the prolific Marcellus dry gas area in northeastern Pennsylvania.”

The first phase of Hillabee, which includes a compressor facility in Choctaw County, AL, and about 20 miles of pipeline looping, received FERC approval last February. The Federal Energy Regulatory Commission gave the go-ahead last month to place the expansion into service.

The second phase, including 11 miles of looping and modifications to existing compressor facilities, is expected to begin construction in 2Q2019.

Transco’s 10,200-mile pipeline network extends 1,800 miles along the Atlantic seaboard from South Texas to New York City. The pipeline is poised to play an increasing role in helping Marcellus and Utica shale gas reach Southeast demand centers as takeaway projects come online, including the Atlantic Coast Pipeline, the Mountain Valley Pipeline and Transco’s own Atlantic Sunrise expansion.

The 1.7 million Dth/d Atlantic Sunrise, consisting of a greenfield segment in eastern Pennsylvania as well as additional compression and looping, received a FERC certificate in February. The project, to serve producers operating in the eastern Marcellus Shale, is scheduled to begin partial service later this year, with full service by mid-2018.