Lease signed for Alpine pipelines

Different mud to be used for horizontal directional drilling under Colville River; holes in river ice will be used to check for escaping mud

Kristen Nelson

PNA News Editor

On Dec. 15 the state and ARCO signed the right-of-way lease for the Alpine pipelines. It was a year to the day from the signing of the right-of-way lease for the Badami pipelines.

The Alpine right-of-way lease signing cleared the way for ARCO Alaska Inc. to begin winter construction of the pipelines which will link its western North Slope Alpine field to Kuparuk River pipelines and facilities.

The process was not automatic. ARCO Alaska had to demonstrate to the state, in last winter’s test borings under the Colville River, that it could use horizontal directional drilling techniques to place pipes with enough precision to keep them within effective distance of the sacrificial anode which helps prevent corrosion.

This fall, a furor developed over a 55,000 barrel mud loss which occurred during last winter’s test borings.

Bradley Fristoe of the Department of Environmental Conservation in Fairbanks, the primary DEC liaison to the Joint Pipeline Office, told PNA Dec. 15 that two things occurred before the right-of-way lease was finalized. The data from last year’s test drilling was analyzed to look at what really happened, to see if there had been environmental damage and to see what needed to be done for the horizontal directional drilling program this year. Then ARCO submitted a plan for this year.

Issues addressed, Fristoe said, included whether drilling mud was getting into the river system. Mud loss was more than expected, he said, but analysis of data can’t say if mud got into the river system. The data review is inconclusive, he said, but we don’t believe significant amounts got into the river.

The 55,000 barrel loss was a continuous process, not a sudden loss, and was spread over a large area. The soils have the capacity of retaining that amount of mud loss, Fristoe said. And during the drilling process, pressure which declined as mud was lost was regained, leaving the impression that the mud was filling holes.

Next year, he said, the program will eliminate even the possibility of mud getting into the river system.

There was also, he said, an issue of reporting the mud loss. Last year’s requirements weren’t really clear and if mud didn’t get into the river then ARCO’s legal requirement to report the mud loss is unclear. For the 1999 program, Fristoe said, we made it clear that we want to know as the drilling progresses. The state will also have a representative at the site seven days a week this winter.

While last year’s plan did not envision mud getting into the river system, Fristoe said, it did envision mud getting into soils surrounding the bore holes with no environmental impact. The mud had slight toxic characteristics in the amounts lost, but, he said, in the amounts lost and after going through drilling, “we feel if they did get into the river they’d be non toxic.”

The mud contained xanthan gum, a thickener used in products such as chewing gum. It’s toxic, he said, only in that it’s sticky: the toxic property is physical, rather than chemical. The mud also contained salt.

Even in the worst scenario, Fristoe said, only slight environmental damage would have occurred, and analysis of ARCO’s reports has led the JPO to believe it would have been almost impossible for that to occur.

This year’s drilling, Fristoe said, will be done primarily with an extended bentonite drilling medium, classified by the U.S. Environmental Protection Agency as practically non toxic. The EPA, he said, does not have a classification less than “practically non toxic.” This mud, he said, contains no xanthan gum.

The type of drilling mud used last year may be used again for some things, but during actual drilling the extended bentonite mud will be used.

JPO has also worked with ARCO on techniques to control loss of circulation.

There will also be a monitoring program this year with a picket fence of monitor holes drilled through the ice across the width of the river. Those sites, Fristoe said, will be monitored twice daily. The monitoring at the holes will begin two weeks before drilling to establish background and there will also be a monitoring hole upstream of the drilling. Bentonite mud stays suspended in water, he said, and if drilling mud is escaping into the river, JPO would expect to see turbidity plumes. Mud escaping into the Colville River is a concern, Fristoe said, because the river is a critical over-winter fish habitat. Fish don’t eat all winter, he said, and don’t move about much and are susceptible to stress.