To accommodate increasing Appalachian Basin natural gas volumes, a 9.5-mile, 16-inch diameter pipeline that would run parallel to an existing line has been proposed to carry Pennsylvania-produced gas through Broome County, NY, to East Coast markets.

The New York Mainline Loop, to be built by Williams unit Williams Field Services Co. LLC and DMP New York Inc., would parallel Williams’ existing 16-inch diameter gas pipe from Susquehanna County, PA, into Windsor, NY, according to a filing with the New York Public Service Commission (NYPSC) (No. 13-02487/13-T-0538). The existing mainline, built by DMP and Laser Northeast Gathering Co. (now owned by Williams) was approved in early 2011 to carry gas from 120 wells into Millennium Pipeline Co. LLC’s (MPC) 30-inch diameter system (see Daily GPI, Feb. 18, 2011).

“Given the success of Williams’ customers, and the prolific nature of the Marcellus Shale wells that have been drilled…” the mainline “is almost, and will be in the near future, at full capacity,” the application said. About 150 wells would be attached in Pennsylvania by the end of this year, with 180 wells attached by the end of 2014.

“All of these prospective wells will be located in Susquehanna and Wyoming counties, PA, and the volumes produced will need pipeline capacity to reach Williams’ downstream interconnection with MPC,” the applicants said. “The New York Mainline and New York Mainline Loop Pipeline will also have the capacity to gather natural gas from wells in the Southern Tier of New York, should the opportunity arise.”

Natural gas drilling using high-volume hydraulic fracturing currently is under moratorium in New York.

“Despite the existence of the New York Mainline and other pipelines (with which the project will compete against), there is still an inadequate presence of natural gas pipelines and gathering infrastructure that are required to collect, aggregate and bring additional quantities of clean burning natural gas to New York,” said the applicants. “The proposed New York Mainline Loop Pipeline will serve this need. Like the New York Mainline…the Loop Pipeline will feed into Williams’ existing facilities for ultimate delivery into the existing interconnection with the MPC.”

Millennium serves New York service territories of National Grid, Orange and Rockland Utilities, New York State Electric and Gas Corp., Corning Natural Gas, and Central Hudson Gas and Electric Corp., the filing said. “Thus, the New York Mainline Loop Pipeline will provide New York, other Northeast markets and their residents, with an additional supply of regionally produced natural gas.”

The proposed pipe would be constructed at a 15-foot offset to the existing system and within the 40-foot permanent right of way (ROW), the application said. The existing ROW would be modified to allow enough space to build and maintain the system. The mainline and Williams’ Dunbar compressor station (CS) currently as designed and constructed have an estimated throughput capacity of 200-225 MMcf/d, according to Williams.

The Loop Pipeline would increase overall capacity by another 100-120 MMcf/d, the applicants said. Williams’ customers already have contracted for the additional capacity, making total contracted capacity to the MPC interconnect about 463 MMcf/d, which is 238-263 MMcf/d more than its current capacity to MPC.

“Completing the Dunbar CS efficiency project and adding the two additional compressor units to the existing Dunbar CS will ultimately allow additional quantities of natural gas to be transported to market for sale…by approximately 150 MMcf/d,” applicants said. “This expansion of compression capacity only, therefore, will help, but it will not eliminate the existing capacity constraint, thereby prohibiting additional natural gas production from being supplied to New York.”

Although other pipelines exist or are planned in proximity to the Loop Pipeline, “those pipelines either serve other exploration and production customers on long-term binding contractual arrangements or will serve as a transmission line and not a gathering line,” said the applicants. “For example, the Bluestone Gathering System, which was recently approved by the NYPSC, will serve as an outlet for the production of natural gas being produced by affiliates of Southwestern Energy” under binding, long-term agreements.

“Thus, notwithstanding the existence of the Bluestone Gathering System, the…Loop Pipeline is still needed to serve as an additional gathering line and an outlet for the increased production and supply by Williams’ customers.” Also, the proposed Constitution Pipeline, backed by a partnership of Williams, Cabot Oil & Gas Corp. and Piedmont Natural Gas, would serve as a regulated transmission line similar to MPC and is “dissimilar” to the existing New York Mainline, Loop and Bluestone systems.