Site Cleanup and Monitoring
Updated: March 6, 2018
- Alternative Water Solutions
- Cleanup and Monitoring
- Site Characterization
- Managing Construction and Excavations within the Plume
Soil and groundwater at the former North Pole Refinery, now the “North Pole Terminal,” have been affected by petroleum spills throughout the refinery’s operation, from the late 1970s until the refinery was shut down in 2014. The terminal’s land still contains fuel product trapped in the soil and groundwater, however, petroleum components in the soil and groundwater have not migrated off the property.
The soil and groundwater are also affected by sulfolane. This industrial solvent was used in the refining process from 1985 until 2014. Spills and other releases of sulfolane started shortly after its use began. In 2009, dissolved sulfolane was found in wells beyond the refinery property. The “plume” of groundwater containing sulfolane beyond the North Pole Terminal property is currently approximately 2 miles wide, 3.5 miles long and over 300 feet deep. It continues to migrate to the north-northwest. The contamination has impacted approximately 350 drinking water wells. Flint Hills Resources Alaska (FHRA) responded to the contamination by:
- Providing alternative water to properties affected by the sulfolane plume,
- Delineating the nature and extent of contamination through a series of intensive site investigation activities, and
- Taking actions to address contamination on the former refinery property.
While Alaska regulations contain cleanup levels for fuel components, there is currently no cleanup level established for sulfolane in Alaska. An explanation of the sulfolane cleanup level situation is provided in the August 2015 newsletter (PDF 1.5M)
In February 2017, a settlement agreement was reached to expand the City of North Pole’s piped water system to all improved properties located within the sulfolane plume or in its anticipated migration path. The piped water expansion will provide residents and businesses permanent protection from sulfolane contamination in drinking water. The agreement—reached between the State of Alaska, FHRA, and the City of North Pole—includes a Potable Water Plan that outlines the elements of the piped water system, and a Revised Onsite Cleanup Plan consistent with the protection provided by the piped water system expansion. Groundwater monitoring continues both on and off the former refinery property to track plume migration and concentration trends.
More information about the 2017 settlement is available in the fact sheet: Summary of Settlement Agreement, Providing Public Water System Expansion, North Pole, Alaska (PDF 3.6M)
Within the sulfolane plume, construction activities that require excavation may need to manage sulfolane-impacted dewatering discharge.
Alternative Water Solutions
People living in the area impacted by sulfolane contamination (to the north and northwest of the former refinery) are currently being provided with alternative drinking water supplies (AWS) for protection from exposure to sulfolane in the groundwater. Residents are provided with either sulfolane-free drinking water (in bulk tanks or in bottles) or point-of-entry treatment systems for their well water. The sulfolane plume migration is being monitored, and bottled water is currently provided to “buffer zone” properties potentially in the migration path of the sulfolane plume.
With the February 2017 announcement of the piped water system expansion, the AWS program is being phased out. AWS provisions and monitoring will continue until connections to the expanded piped water system are available. AWS program monitoring has been documented in annual reports listed below, available on our Documents page:
- Alternative Water Solutions Program 2016 Annual Report North Pole, Alaska (February 2017)
- Alternative Water Solutions Program 2015 Annual Report North Pole, Alaska (February 2016)
- Alternative Water Solutions Program 2014 Annual Report North Pole, Alaska (February 2015)
- Alternative Water Solutions Program - Management Plan Flint Hills Resources Alaska, LLC North Pole Alaska (October 2014)
See also the page on the North Pole Piped Water Expansion.
Cleanup and Monitoring
2017 Revised Onsite Cleanup Plan
In February 2017 and as part of the settlement agreement, FHRA submitted a Revised Onsite Cleanup Plan. Under this revision, the 2014 Onsite Cleanup Plan addressing contamination on the North Pole Terminal property was modified. Operation of the onsite groundwater extraction and treatment system was replaced by intensive groundwater monitoring in July 2017.
During its years of operation, the treatment system greatly reduced the amount of sulfolane migrating off the refinery property. Halting the system is not expected to significantly impact the offsite plume. Intensive monitoring will be performed to evaluate the impacts of turning off the system. Engineering and administrative controls remain in place to protect workers.
The plan's updated goal for groundwater is to prevent contaminant migration off the refinery property above DEC cleanup levels. For sulfolane, which does not have a cleanup level, offsite migration is not to exceed a concentration of 400 parts per billion. Although some sulfolane is anticipated to migrate off the terminal property, it is not expected to exceed this groundwater goal or significantly change the extent of the offsite sulfolane plume.
Contingencies are in place to resume active treatment if the Plan goals are not met. Details about the ROCP are summarized in the following: Fact Sheet: The 2017 Revised Onsite Cleanup Plan & Offsite Potable Water Plan, February 2017 (PDF 2.6M)
Potable Water Plan and Plume Monitoring
The 2017 Potable Water Plan outlines the provision of sulfolane-free drinking water through expansion of the City of North Pole's piped water system and includes groundwater monitoring requirements until the plume meets a cleanup level to be set by the State of Alaska.
Groundwater samples will be collected from monitoring wells to track plume migration as necessary to protect residences and businesses located outside of the area to be served by the piped water system.
Details about the Potable Water Plan are summarized in the following: Fact Sheet: The 2017 Revised Onsite Cleanup Plan & Offsite Potable Water Plan, February 2017 (PDF 2.6M)
Under DEC oversight, FHRA currently collects groundwater samples from wells located both on and off the refinery to monitor plume migration and sulfolane trends:
- Onsite monitoring results are compiled into semi-annual reports and are available on the Documents page, Onsite Plume.
- Offsite monitoring results are compiled into semi-annual reports and are available on the Documents page, Offsite Plume.
- Maps of the results of groundwater monitoring are posted on the Maps page, with the most recent at the top.
Under Alaska regulations (18.AAC 75.335), the extent of contamination is to be characterized before proceeding with cleanup at a contaminated site. The site characterization requirements generally include investigation activities to determine the types of contaminants present, the source areas, possible risk to people and the environment, the possible need for interim cleanup actions, and the extent of the contamination, both horizontally and vertically. The site characterization reports include an evaluation of potential cleanup activities that may be appropriate at the site. More information on the State of Alaska cleanup process is available at the links below:
Multiple site investigations were performed on the North Pole Refinery, beginning in the 1980s, but the 2009 discovery of sulfolane beyond the refinery property instigated a new round of very detailed characterization efforts. Investigations were performed onsite to evaluate the source of the sulfolane contamination and refine the understanding of the nature and extent of petroleum contamination. Offsite investigations assessed the size and boundaries of the sulfolane contamination. Hundreds of monitoring wells were installed, and thousands of groundwater samples were collected. The most recent and complete characterization reports are listed below and found on the Site Characterization portion of our Documents page:
- 2013 DRAFT Onsite Site Characterization Addendum Report
- 2013 DRAFT Offsite Site Characterization Addendum Report
- 2012 Site Characterization Addendum
- 2011 Site Characterization Report
Other project documents and reports on site investigation and remediation are available on the Documents page.
Managing Construction and Excavations within the Plume
Releases of sulfolane at the former North Pole Refinery have resulted in a contaminated groundwater plume that extends throughout much of the City of North Pole, Alaska, and beyond the city boundaries. The potential exists for development as well as utility maintenance projects within North Pole and beyond to be impacted by the logistics for managing excavations that require dewatering within the sulfolane plume boundary. A plan for managing excavation dewatering fluids in compliance with applicable regulations is necessary to reduce impacts on projects in North Pole and surrounding impacted areas.
An Interim Excavation Dewatering Management Plan, finalized in 2014 and updated in 2017, provides guidance for managing excavation water generated during construction dewatering activities in the vicinity of the North Pole sulfolane groundwater plume. The overarching management goals are to minimize the volume of contaminated water to be discharged and to manage the discharge so that it does not cause sulfolane contamination in areas that were previously uncontaminated.
- Final Interim Management Plan for Excavation Dewatering in the North Pole Sulfolane Plume (October 2017)