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Operations Plan for Nikiski Soil Treatment Facility

How to submit a comment


Property Location Map

Property Location Map (Figure 1). Courtesy: STT Operations Plan.

Site Map Figure 2

Site Map (Figure 2). Courtesy: STT Operations Plan.

Soil Treatment Technologies (STT) has submitted an Operations Plan for a new thermal treatment facility for petroleum-contaminated soil. The facility site is located at 52520 Kenai Spur Highway in Nikiski, Alaska.

The Operations Plan is listed on our public notice site as The Operations Plan for an Offsite or Portable Treatment Facility, Soil Treatment Technologies, LLC.

The Operations Plan has been submitted to the Department of Environmental Conservation (DEC) for approval in accordance with 18 AAC 75.365 and 18 AAC 78.273. The DEC Contaminated Sites Program is in the process of reviewing the plan to ensure procedures are in place to protect human health, the environment and Alaska's natural resources.

Please help support the review process by submitting a public comment. The public comment period for this application begins on August 21, 2021 and ends at 11:59 p.m. on September 4, 2021. Any person wishing to submit comments regarding this Operation Plan may do so electronically via our public notice site or use the submit public comment button.

If you are unable to submit comments electronically, you may submit them in writing to Lisa Krebs-Barsis, Department of Environmental Conservation, SPAR/CSP, 555 Cordova St., Anchorage, AK 99501, 907-269-7691 (phone), 907-269-7687 (fax), or

All comments will be reviewed. The department may request additional information or changes to the operations plan from STT if comments received identify issues under the regulatory purview of the Contaminated Sites Program.


What is Thermal Desorption?

STT’s facility uses thermal desorption as its treatment method. The following information comes from the Environmental Protection Agency’s (EPA) A Citizen’s Guide to Thermal Desorption:

Thermal desorption removes organic contaminants from soil by heating them in a machine called a “thermal desorber.” This evaporates the contaminants. Evaporation changes the contaminants into gases and separates them from the solid material.

Thermal desorber heats contaminated material to evaporate contaminants. Courtesy: EPA A Citizen's Guide to thermal Desorption

The desorber can be used onsite or offsite. Soil may be prepared for treatment by screening out debris and oversized material. The prepared soil is placed in the thermal desorber to be heated.

Gas collection equipment captures the contaminated vapors. Vapors are destroyed in the thermal oxidizer, which heats the vapors to temperatures high enough to convert them to carbon dioxide and water vapor.

It is important to note that thermal desorption is not the same as an incinerator which heats contaminated materials to temperatures high enough to destroy the contaminants.

For more details on thermal desorption, please see EPA’s A Citizen’s Guide to Thermal Desorption.

Frequently Asked Questions

How will the proposed facility operate?

Petroleum-contaminated soil will be delivered to the facility and placed into a staging area with a petroleum-resistant surface inside a covered storage building.

Inside the storage building, the soil will be screened to remove all rocks and material over 2-inches in diameter.

Any oversized rocks and material will be pressure-washed in containment to remove any residual soil which will be added back into the screened soil.

The screened soil will be stockpiled on a petroleum-resistant, sealed, asphalt pad in a covered, enclosed, containment area while awaiting treatment.

The soil will then be transferred onto a conveyor belt which leads to a dryer drum.

The soil will be heated in the dryer drum to 600° Fahrenheit to remove the contaminants, which will be discharged to the baghouse as vapors and fine particulate.

A baghouse uses filter bags to filter gases and fine particulate. Filtered gases are pulled out of the baghouse by a fan into the secondary treatment unit (thermal oxidizer).

The thermal oxidizer heats up to 1,400°-1,600° destroying organic vapors. Gases that are emitted will be monitored in accordance with the permit issued by DEC’s Division of Air Quality.

Fine material from the baghouse filters is mixed back with the soil and both go to a conditioner that cools and rehydrates the treated soil.

The soil then moves onto a radial stacker which creates a stockpile on a steel plate pad.

The post-treated soil storage cells will be covered with polyethylene liners when treated soil is not being actively stacked.

The soil will remain on the pad until post-treatment sample results demonstrate that the soil meets the most stringent cleanup levels for the contaminants of concern.

Once the soil analytical test results show that the soil has been successfully remediated, it can be returned to the original contaminated site or stockpile at the facility for use by other contractors for projects.

What regulatory authority does the DEC Contaminated Sites Program have regarding the Nikiski facillity?

The DEC Contaminated Sites Program’s regulatory authority to review and approve of offsite and portable treatment facilities is 18 AAC 75.365 and 18 AAC 78.273. Operations plans are reviewed according to these regulations and the Operation Requirements for Soil Treatment Facilities (DEC 2013) guidance adopted by regulation.

How will DEC ensure the facility is operating in accordance with the Operations Plan?

The DEC Contaminated Sites Program has multiple systems in place to ensure the facility is operating according to regulation and their operations plan. First, according to the Alaska regulations, soil cannot be accepted by the facility without written approval from a DEC contaminated Sites or Prevention, Preparedness, and Response project manager. When petroleum-contaminated soil is identified, the Responsible Party (contaminated soil waste generator) or their consultant will contact STT to see if they can bring the contaminated soil to the facility and will complete a Contaminated Media Transport and Treatment or Disposal Approval Form. The form will be sent for review to DEC staff already working with the Responsible Party. The DEC staff will review the information about the contaminated site or spill to ensure the contaminants present in the soil are limited to petroleum or petroleum constituents before approving the transport of contaminated soil to STT.

Secondly, following the treatment of each batch of soil, STT will submit analytical results of post-treatment samples to DEC for review and comparison with the most stringent cleanup levels before the soil can be released. These samples must be collected by an impartial third-party who meets the DEC regulatory requirements of a Qualified Environmental Professional or Qualified Sampler.

Finally, STT will submit an annual report to the DEC Contaminated Sites Program which documents inspections and maintenance of the pad, water treatment discharge results, and annual groundwater well sample results. The DEC Contaminated Sites Program staff will conduct facility inspections as well.

How Will DEC Ensure the Property is Not Contaminated When the Facility closes?

Facility closure requirements are described in regulation and outlined in Section 7 of the Operations Plan. STT has conducted a baseline assessment of the property to determine the conditions of the soil and groundwater prior to facility operations. At the time of closure, a closure assessment will be conducted within 90 days of the end of the operations. STT will provide a work plan for DEC for approval to ensure the assessment meets DEC’s requirements at the time of closure. The contaminated soil containment cell and post-treatment soil containment will be removed and the underlying soil will be sampled to make sure that it isn’t contaminated. An impartial third-party Qualified Environmental Professional will prepare a report for review and approval by the DEC Contaminated Sites Program. Any cleanup needed following the closure assessment is required to be completed within two years.

Submit a Public Comment

Please review the above information, STT Operations Plan and Public Notice, before submitting a public comment.

The full contents of all submitted comments are considered public records and will be posted online in full during the public comment period.

The public comment period for this application begins on August 21, 2021 and ends at 11:59 p.m. on September 4, 2021. Comments must be received by 11:59 pm on September 4, 2021.

The State of Alaska, Department of Environmental Conservation complies with Title II of the Americans with Disabilities Act of 1990. If you are a person with a disability who may need an accommodation in order to participate in this public process, please contact Brian Blessington at 907-269-7660 or TDD Relay Service 1-800-770-8973/TTY or dial 711 to ensure that any necessary accommodations can be provided.

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