Dallas-based Crosstex Energy LP is moving ahead with the second phase of a natural gas liquids pipeline project in Louisiana that will allow the partnership to move 50,000 additional barrels of liquids a day.

The project includes a 32-mile extension of a pipeline that provides gas to customers in the Mississippi River corridor; four pump stations; and 57 miles of natural gas liquids pipelines that stretch from the partnership’s Eunice fractionation facility to its Plaquemine natural gas processing plant.

Phase I of the project includes a 130-mile, 12-inch-diameter pipeline that will connect its Eunice facility to Mont Belvieu supply pipelines in east Texas.

Fractionation is the separation of natural gas liquids into individual liquid hydrocarbons, such as ethane and butane.

The total cost of both projects is estimated at $680 million to $700 million. The original estimate for Phase I was between $180 million to $220 million.

Crosstex expects to complete the first phase in mid-2013 and the second phase during the second half of 2014.

In addition, Crosstex Energy announced it has signed 10-year sales agreements with Dow Hydrocarbons and Resources LLC. Under the sales agreements, Crosstex will deliver ethane and propane, produced at the partnership’s new Plaquemine fractionator, into Dow’s Louisiana pipeline system. The partnership also will deliver natural gas Dow’s Plaquemine facility.