JUNEAU — Flint Hills’ refinery in North Pole has had a long history of leaks and spills from the day it opened, according to lawsuit filed by the state of Alaska over the responsibility for a sulfolane plume emanating from the refinery.

The court documents filed in the Fairbanks Superior Court outlines nearly 400 documented spills of petroleum products at the refinery that have resulted in hundreds of thousands of gallons of oil products spills since it opened in 1977.

The court documents outline the history of the North Pole refinery from its opening in 1977 under Earth Resources of Alaska, its 1970 sale of the refinery to MAPCO, the 1998 purchase of MAPCO by Williams of Alaska and later the 2004 sale of the refinery to Flint Hills.

During the first decade of operation, first under Earth Resources of Alaska and then MAPCO, which bought the refinery in 1980, there were 92 documented spills that resulted in more that 160,000 gallons of petroleum materials being leaked or spilled at the site. More was spilled because MAPCO was able to retrieve more than 276,000 gallons by June 1988.

So much material had leaked during the first three years, the documents report, that a fire was triggered during excavation work in 1980.

The contamination was identified as mostly benzene and corrective actions were undertaken in 1987, even though groundwater at the site was found to be unaffected, according to the court documents.

The state’s filing jumps ahead to the 1998 purchase of MAPCO by Williams Alaska, which it notes assumed all legal responsibly for the site’s operations.

Sulfolane, the chemical that is of concern today, was found in the groundwater during tests by Williams Alaska’s environmental consultants in 2001. At the time, little was known about the health impacts of the chemical and the Alaska Department of Environmental conservation didn’t consider it a regulated contaminant. The state did recommend close monitoring, which the company conducted.

Sulfolane, unlike oil products, easily mixes with water, a trait that has lead to the contamination of the surrounding area, while much of the earlier spills have remained on-site.

During Williams Alaska’s six-year ownership of the North Pole refinery, the state’s documents report that there were 126 documented spills and leaks resulting in the release of 21,197 gallons of petroleum products.

The state said it considers those numbers to be underreported, noting that Williams Alaska “intentionally failed to report or under-reported spills and leaks that occurred during its ownership and operation of the North Pole refinery. Williams Management has acknowledged those practices and has attributed them to a ‘fear of being disciplined or from fear of negatively impacting “the numbers.”’”

Flint Hills purchased the refinery in 2004 and “agreed to take responsibility for the sulfolane that was “existing, known and disclosed.”

During the past 10 years of Flint Hills’ ownership, the court documents state that there were 177 documented spills.

As for the sulfolane spill, Flint Hills maintained the contract with Williams’ environmental consultant, which continued to find higher and higher levels of the chemical. Months after the purchase, the consultants found sulfolane levels 11 times higher than first reported in 2001.

The court documents suggest that it came from a continuous source, not a one-time spill, as it notes Flint Hills “erroneously” concluded in 2005.

The environmental consultant delivered a final report in 2006 that advised the company should begin to conduct more rigorous monitoring of the sulfolane and watch for its migration off-site.

Flint Hills, according to the court documents, waited 18 months to react, which it did by hiring a new consultant. That consultant returned the same recommendation and Flint Hills installed improved monitoring wells in 2008.

But by that time the sulfolane had already migrated off site and was found in North Pole-area wells, according to the court documents.

Throughout the time, DEC has also continually tightened its standards on what are acceptable levels for sulfolane as new information on the potential toxicity of the chemical becomes available.

A legislative hearing on the issue earlier this Legislative session suggested that the Flint Hills sulfolane spill is the largest such spill in the country.

Flint Hills has reportedly spent $75 million on the cleanup and mitigation for the sulfolane spill, providing clean water to some 550 homes and businesses in the area.

The issue of long-term responsibility for the spill is an ongoing issue. Flint Hills failed to extract payment from Williams Alaska because the issue was time-barred in court.

The state, however, filed a lawsuit — the source of this timeline — Thursday to determine who ultimately is responsible for the spill. The state holds that both Williams and Flint Hills allowed the spill to occur and is requesting that they pay for the cleanup and mitigation. Flint Hills, however, ssaid because most of the spill occurred under Williams Alaska, it should be held responsible.

A court battle regarding the issue is possible, but the parties also could agree to a settlement.

Flint Hills announced plans to close the plant earlier this year, citing the state’s cleanup costs for the sulfolane spill. It has signaled that it has interested buyers lined up to buy the North Pole plant and keep it in operation.

Contact staff writer Matt Buxton at 459-7544. Follow him on Twitter: @FDNMpolitics.