Project History: Technical Activity and Public Outreach
Updated: February 20, 2018
Table of Contents
1970 - 2008
View more information on the site history of the North Pole Refinery in DEC's Database of Contaminated Sites
- Refinery begins production using crude oil from the Trans-Alaska Pipeline.
- 1970s to early 1980s
- Petroleum product leaks from above-ground storage tanks, consequently these tanks are taken out of service.
- MAPCO purchases the refinery.
- Sulfolane unit installed.
- DEC issues a Compliance Order by Consent, which outlines a cleanup and monitoring strategy for the petroleum contamination.
- Mid to late 1980s
- Monitoring well data indicates that groundwater on the refinery Is contaminated with petroleum compounds, such as benzene, ethylbenzene, toluene, xylenes, (BTEX) trimethylbenzenes and naphthalene above DEC’s regulatory maximum contaminant levels for drinking water. The drinking water used at the refinery is tested and found to be unaffected, as is the city water system. At this time, the refinery begins treatment and monitoring of the groundwater and performs further site characterization.
- The US Environmental Protection Agency (EPA) issues two Resource Conservation and Recovery Act (RCRA) Administrative Orders to MAPCO. The orders outline a cleanup and monitoring strategy for the RCRA hazardous waste violations.
- MAPCO merges with The Williams Companies.
- The Williams Companies sells the facility to Flint Hills Resources.
October to November
- Sulfolane is discovered in wells north of the refinery property boundaries: Flint Hills (FHR) begins testing groundwater in monitoring wells outside of its property, near private homes with drinking water wells. Sulfolane concentrations in the monitoring wells are higher than expected, although below the 350 micrograms per liter cleanup level previously established for onsite wells.
- Flint Hills, as the responsible party, notifies DEC with the results and with a plan to immediately supply alternate water and begin testing residential wells. Bottled water is provided to those impacted.
- DEC asks the Alaska Department of Health and Social Services (DHSS) for assistance in reviewing the sulfolane cleanup level for its protectiveness of human health.
View more detailed information on the site history of the North Pole Refinery in DEC's Database of Contaminated Sites.
- November 20
- A comprehensive DEC website on the sulfolane investigation is established.
- November 23
- DEC holds its initial public meeting in North Pole. Representatives from DEC, Flint Hills Resources and DHSS participate.
- FHR continues to provide bottled water to those impacted.
- Flint Hills completes a comprehensive search for drinking-water wells and sampling effort.
- City of North Pole municipal wells are tested weekly from October 2009 through February 2010.
- The federal Agency for Toxic Substances and Disease Registry (ATSDR) publishes a health consultation recommending a public health action level of 25 parts per billion of sulfolane in drinking water.
- DEC forms a collaborative Technical Project Team (TPT) to provide comprehensive and coordinated oversight for the investigation. The team consists of government and industry representatives and multidisciplinary experts.
- Flint Hills installs new wells for the City of North Pole public water system, even though sulfolane concentrations in the former City wells were consistently below 10 parts per billion.
- Rigorous inspections of the refinery are conducted to identify any potential ongoing sources of sulfolane contamination.
- DEC and FHR develop a site characterization work plan to investigate the extent contamination and evaluate exposure.
- The TPT completes a garden sampling project involving several local gardeners to investigate if sulfolane accumulates in plant tissues.
- FHR begins a pilot study of a granular activated charcoal (GAC) technology for removing sulfolane from groundwater.
- DEC establishes a group email list to update stakeholders on the investigation of sulfolane.
- Frequently asked questions (FAQ) are added to the website and updated periodically.
- DHSS issues a Fact sheet: Sulfolane Health Fact Sheet (PDF)
- DEC holds a second public meeting to review the investigation.
- DHSS issues a
- DEC issues a fact sheet: Update on Sulfolane Cleanup (PDF)
- Technical briefings for local legislators and mayors are begun and held regularly.
- DHSS issues fact sheet Community Health Concerns about Sulfolane (PDF)
- Community open house is held
- DHSS issues a fact sheet: Results of the North Pole Garden Sampling Project: Testing of Early Harvest Plants for Sulfolane (PDF)
- DHSS issues a press release: Sulfolane levels low or undetected in tested North Pole garden plants (PDF)
- DEC holds its second community open house to review the Technical Project Team’s current work and findings on the sulfolane investigation.
- DHSS issues a press release: Tests results released from sulfolane garden project
- DHSS issues a fact sheet, Final Results of the North Pole Garden Sampling Project (PDF)
- The first Technical Project Team newsletter (PDF), the TPT Year in Review, is published and sent to all interested stakeholders.
- A community workshop is held reviewing information on sulfolane's effect on health from the DHSS, and the ATSDR's newly released Health Consultation–Sulfolane (PDF)
- The second newsletter (PDF) is published.
- A community survey is conducted online to learn community preferences for communications.
- The sulfolane plume is found to extend 3 miles downgradient from the refinery and approximately 2 miles wide at its widest area (off-site). Sulfolane is detected in private wells above and below permafrost.
- New North Pole public drinking water system wells begin operation.
- DHSS issues the final results of the North Pole garden sampling (PDF), recommending that North Pole gardeners in the plume area use an alternative water source to grow fruits and vegetables until more information is known.
- Flint Hills submits a feasibility study to build home treatment systems to treat sulfolane using granulated activated carbon filters.
- ATSDR develops action levels for sulfolane in drinking water, with the most protective level being for infants, at 20 parts per billion, in its Health Consultation – Sulfolane (PDF)
- DEC issues guidelines for the groundwater analysis of sulfolane, creating specific procedures that all laboratories analyzing water for sulfolane must meet.
- The groundwater monitoring network continues to be expanded on and off the refinery property for horizontal as well as vertical delineation of contamination.
- FHR's point of entry water treatment systems receive certification from the Water Quality Association (PDF).
- Available private well records and logs are reviewed to enhance the understanding and interpretation of the private well sampling data.
- FHR identifies past spills and releases through a records review, which indicates that sulfolane releases into groundwater were mostly from subsurface wastewater containment systems.
- FHRA inspects and tests the refinery sump systems, correcting weaknesses, encouraging plant-wide spill prevention and control, and initiating preventative maintenance programs.
- Surface water samples collected from the refinery gravel pits and the Badger Slough do not contain sulfolane.
- FHRA and its contractors continue work to provide an alternate water supply to the homes outside the City of North Pole limits with wells impacted by sulfolane: The residential and commercial locations have one of the following permanent solutions: an in-home water treatment system, a bulk water tank or long-term bottled water delivery services. Bulk tanks are provided to home for gardening water, if requested.
- DHSS completes its Health Consultation (PDF)
- National Toxicology Program (NTP) accepts sulfolane into its program to conduct additional research on the chemical’s health effects and begins designing toxicity studies.
- EPA publishes a provisional peer reviewed toxicity value (PPRTV) for sulfolane (PDF).
- DEC establishes an agreement with the University of Alaska, Fairbanks (UAF) to conduct research on some of the factors that impact the fate and transport of sulfolane in the North Pole aquifer, including degradation of sulfolane and transport through a discontinuous permafrost aquifer.
- FHRA submits a draft risk assessment, which includes calculations of different alternative cleanup levels based on different assumptions.
- DEC sets a site-specific cleanup level of 14 parts per billion (as of 2014 this level has been appealed and is under review).
- EPA announces completion of a Preliminary Assessment of the refinery
- FHRA submits Feasibility Studies that do not meet the established requirements.
- The third newsletter (PDF) is published
- DHSS issues a press release – North Pole sulfolane health impact evaluation (PDF).
- The fourth newsletter (PDF) is published
- A community open house is held to update the community.
- The fifth newsletter (PDF) is published.
- The sixth newsletter (PDF)is published.
- A community open house is held at North Pole Plaza Mall.
- The seventh newsletter (PDF) is published.
- DEC letter and survey mailed to all property owners in affected area, living in- and out-of-state, expands communication with those affected.
- DHSS issues a fact sheet Health Recommendations and Next Steps (PDF) summarizing recommendations to date.
- State Agency open house, at North Pole City Hall, with DEC staff and team, and DHSS representatives.
- August through September
- Responses sent to property owners who responded to the June survey with questions or issues.
- The eighth community newsletter (PDF) is posted on the website.
- FHRA conducts an additional door-to-door survey of homes on City water in the affected area to ensure people are aware of the DHSS recommendation to use non-impacted water to water vegetable gardens.
- FHRA conducts a permafrost mapping survey to better understand permafrost formations, improving understanding of groundwater movement and aiding in predicting plume behavior.
- About 80 additional monitoring wells are installed and about 240 soil and water samples collected over the summer and fall.
- UAF continues working with DEC conducting research on the degradation of sulfolane and transport of sulfolane through discontinuous permafrost.
- Soil and surface water from gravel pits are sampled for sulfolane.
- Soil is sampled from lawns and flower gardens watered with sulfolane-containing water.
- DEC's Spill Prevention and Response Division gives conditional approval to FHRA’s Human Health Risk Assessment and establishes a cleanup level of 14 parts per billion (ppb) for sulfolane at the North Pole Refinery.
- Gravel pit study results (PDF) show that the surface water in gravel pits does not contain sulfolane, and there's no danger in moving gravel to other areas.
- FHRA files a Request for an Adjudicatory hearing to DEC (PDF 1.5M) to appeal the Spill Prevention and Response Division's November decision to establish a site-specific cleanup level of 14 ppb. (DEC fact sheet, April 2014 (PDF)
- FHRA submits the draft Alternative Water Systems Management Plan for DEC review.
- FHRA delivers draft Site Characterization Report Addendums.
- Public open house is held at North Pole City Hall, with Flint Hills representatives, DEC staff and team, and a DHSS representative.
- DEC issues a Public Notice of Flint Hills' request for Adjudicatory Hearing and request for stay.
- The ninth community newsletter (PDF) is issued.
- The National Toxicology Program (NTP) begins studies on the health effects of sulfolane to evaluate aspects not previously researched.
- The State files a lawsuit against the current and former owners of the North Pole Refinery. DEC continues oversight of the site investigation and cleanup.
- DEC issues a garden soil study report from testing indicating that using sulfolane-contaminated water on gardens does not leave residual sulfolane in the soil.
- DEC's Commissioner “vacates” the Spill Prevention and Response Division’s 14 parts per billion cleanup level decision. This decision meant no cleanup level number was in effect. He also gave instructions for the Division’s further consideration and explanation in a setting a new cleanup level.
- FHRA submits a supplement to its Human Health Risk Assessment, proposing a cleanup level of 362 ppb.
- FHRA expands the groundwater extraction system at the refinery as part of their proposed interim remedial actions.
- UAF continues working with DEC conducting research on the degradation of sulfolane and transport of sulfolane through discontinuous permafrost.
- DEC develops an interim best management practices plan to assist with the management of dewatering activities near or within the sulfolane plume. See June 2014 newsletter (PDF) for summary.
- The sulfolane plume's approximate size to date is 3.5 miles downgradient (northwest) from the refinery, 2 miles wide, and over 300 feet deep.
- September 16 to 17
- At SPAR Division’s request, an independent, expert peer review of the available reference doses for sulfolane is conducted in Fairbanks by the non-profit organization Toxicology Excellence for Risk Assessment (TERA). This is part of the division’s detailed analysis ordered by the Commissioner. A reference doses is one of a number of factors used in calculating a cleanup level.
- DEC approves an Onsite Cleanup Plan proposed by Flint Hills Resources for contaminated soil and groundwater within the boundaries of the refinery property.
- See the Cleanup Plan documents
- See DEC’s press release
- TERA report is released, concluding that none of the reference doses (or toxicity values) aligned perfectly with the recommendations of the expert panel. Although the report concluded that the value proposed by FHRA most closely aligns with the panel’s conclusions, the experts identified a number of uncertainties about the toxicity of sulfolane including lack of reliable, long-term studies on the health effects of long-term exposure to sulfolane. (See the report).
- DEC meets with the National Toxicology Program and learns they plan to begin long-term studies to address the remaining uncertainties about the health effects of exposure to sulfolane.
- The National Toxicology Program (NTP) initiates a 2-year study to address important data gaps regarding sulfolane exposure, including the effects of long-term exposure to this chemical. The NTP studies are expected to provide a clearer picture of the risks associated with sulfolane exposure. (See the NTP fact sheet for more details (PDF)
- SPAR Division announces it will wait to set a regulatory cleanup level for sulfolane until the new NTP research is complete. (See DEC’s Press release on the NTP studies (PDF)
- FHRA requests a modification of the groundwater extraction system performance standard, DEC denies the request. Notice of Request for Adjudicatory Hearing on DEC's Denial of a Petition to Modify Groundwater Extraction System Performance Standard
- DEC publishes a fact sheet concerning new research on the toxicity of sulfolane being conducted by the National Toxicology Program (PDF).
- DEC updates website with new Frequently Asked Questions (PDF).
- DEC issues the tenth community newsletter (PDF).
- DEC holds a public open house at North Pole Branch Library, with representatives from DEC, DHSS, and Flint Hills.
- The 2014 Onsite Cleanup Plan is modified to cease operation of the western groundwater extraction and treatment system, due to low levels of influent contamination. Operation of the original (eastern) onsite treatment system and groundwater monitoring continues.
- Information on property concerns regarding sulfolane contamination is provided to the public through the website.
- Flint Hills Resources Alaska and the State of Alaska announce on February 7th, 2017, that they will be working with the City of North Pole to significantly expand their piped public water system to provide sulfolane-free drinking water to residents impacted by the sulfolane groundwater plume. See fact sheet on the settlement agreement (PDF)
- A 2017 Onsite Cleanup Plan is released.
- Under the 2017 Revised Onsite Cleanup Plan, operation of the onsite groundwater recovery and treatment system is replaced by intensive groundwater monitoring. Contingencies are in place to resume active treatment if the plan goals are not met. (See fact sheet on the Revised Onsite Cleanup Plan (PDF)
- On February 25 an estimated 100 people attend the Community Open House, held at the North Pole Plaza by DEC, the Alaska Department of Health and Social Services, the City of North Pole and Flint Hills Resources Alaska. Attendees talk with representatives from the three parties to the agreement regarding specifics of the project. DEC solicits feedback from community members through March 27.
- DEC publishes fact sheets:
- Summary of Settlement Agreement Providing Public Water System Expansion (PDF)
- 2017 Revised Onsite Cleanup Plan & Offsite Potable Water Plan (PDF)
- Well Water Versus City Water Cost Comparison (PDF)- updated December 2017
- DEC updates website with new Frequently Asked Questions (FAQs) (PDF).
Sulfolane Use in the U.S. and at the former North Pole Refinery
Sulfolane is an industrial solvent used to extract aromatic compounds from hydrocarbon mixtures and to purify natural gas. It is on the U.S. EPA's High Production Volume Chemical List that indicates the volume of sulfolane either manufactured or imported into the U.S. exceeds one million pounds per year.
At the the former North Pole Refinery, sulfolane was used to extract aromatics from naptha to produce gasoline. In the aromatic extraction process, sulfolane was initially mixed with the petroleum feedstock (naphtha and light distillates). The sulfolane extracted the aromatics from the feedstock, and the aromatic-laden sulfolane was sent to a stripper for aromatic removal before returning to the extraction unit. Sulfolane as used in the refining process was dissolved in gasoline but it is more soluble in water, which allowed it to dissolve in, and be carried along with groundwater.
There are at least 150 similar extraction units in the U.S. Sulfolane use in North Pole began in 1985. While gasoline was the only product that required the sulfolane extraction process, sulfolane may have migrated into other refinery products due to incidental carryover through the refinery's piping system. Fuels that may have contained sulfolane in the past include #1 fuel oil (jet fuel) and #2 fuel oil (diesel fuel). Only gasoline was monitored for sulfolane content as it was the only fuel produced at the refinery with a sulfolane specification.