The southern portion of the Keystone XL pipeline, known as the "Gulf Coast Project", is making its way home to Port Arthur refineries. The 485-mile pipeline from Cushing, Oklahoma to Southeast Texas began in August of last year. It's expected to be completed by mid-summer and running by the end of the year.

By the time of completion, Transcanada says 4,000 workers will put 1.3 million man hours into the project.

Sunland Construction is the contractor for the project. Workers have cleared hundreds of miles of land. In Sour Lake, they've hauled in the pipe and are currently welding the 36-inch diameter pieces together.

Once welded and coated with paint, they use x-ray equipment to look for cracks. A static sound indicates there's a problem and leaves a black dot to notify workers where to sand and buff out the hole.

One it passes inspection, a trench will be dug next to the pipeline.

"This trench will have four feet of cover over it. The pipeline will be lowered in and then backfilled and the land will be restored," says David Dodson, Gulf Coast Project spokesperson.

A muddy trench on Aggie Road has already been built; mud that workers say will then be used by farmers for their land.

For now, they're putting in the pipe, digging sideways underneath the LNVA canal.

"You drill a hole, back it up, put a head on to expand the hole, then put the bore in until it's big enough for this pipe to go underneath," says Dodson.

Workers use two color-coded pipes. Thicker red pipes are used under roads, railways and waterways, like the LNVA.

"It's just an added safety measure. We selected a higher thickness of pipe," says Dodson.

For longer stretches of land, green piping is used.

On the ground, workers lay plastic and mats for environmental protection. Transcanada tells 12News protecting wetlands and farm land is paramount.

"We have a small army of environmental inspections who are with us every day making sure we are living up to the very strict environmental standards that are established for piping," says Dodson.

Once the Gulf Coast Project goes into service late this year, Transcanada says all landscape will return to it's normal look. But, what won't be seen by the naked eye is 700,000 barrels of crude oil pumping 15 feet below the surface.

Pump stations that are 50 miles apart are also under construction.

There's also a 47-mile Houston Lateral Project, which is an additional project under construction.

It will transport oil to Houston refineries.