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Site Report: Unalakleet NALEMP Kotongan Lake AST

Site Name: Unalakleet NALEMP Kotongan Lake AST
Address: Northeast of Tank Road and Pond Road Intersection, Unalakleet, AK 99684
File Number: 630.38.013
Hazard ID: 26159
Status: Active
Staff: Axl LeVan, 9074512156 axl.levan@alaska.gov
Latitude: 63.879173
Longitude: -160.789158
Horizontal Datum:WGS84

We make every effort to ensure the data presented here is accurate based on the best available information currently on file with DEC. It is therefore subject to change as new information becomes available. We recommend contacting the assigned project staff prior to making decisions based on this information.

Problems/Comments

A 400,000-gallon aboveground storage tank (AST) was located within the city of Unalakleet on property that is owned by the Unalakleet Native Corporation (UNC). Records indicate that the AST was built by the United States Air Force (USAF) in 1959 and was used to store diesel fuel. Sometime around 1970 the tank was decommissioned and ownership of the area was transferred to UNC. UNC used the tank for an additional 10 years. The Native Village of Unalakeet (NVU) issued a contract (with NALEMP funding) for demolition of the AST and pipeline with post-demolition soil sampling and analysis to evaluate potential fuel contamination. The demolition and sampling work plan was reviewed and approved by ADEC. In August 2013 the AST demolition and confirmation sampling were completed. The footprint of the AST was 1,590 square feet and the estimated linear feet of the associated piping was 490 linear feet. Approximately 200 feet of the pipeline were underwater in Kotongan Lake. Representative field screen samples were collected every 10 feet and laboratory samples were collected every 20 feet only in areas where the pipeline was above water. Five laboratory samples collected from the base of the tank and seven laboratory samples collected from the pipeline indicated levels of DRO above the ADEC migration to groundwater cleanup level. The pipeline samples that showed elevated levels of DRO were localized to the east side of the Kotongan Lake in the general vicinity of the obvious 90 degree corner in the former pipeline. The Contractor estimates that approximately 50 cubic yards (CY)may need to be excavated from the site; 40 CY from the tank pad area and 10 CY from along the pipeline. DEC has indicated that additional site characterization including an evaluation of groundwater and surface water on site is required prior to proceeding to a cleanup plan.

Action Information

Action Date Action Description DEC Staff
11/26/2013 Site Added to Database A new site has been added to the database Mitzi Read
11/26/2013 Meeting or Teleconference Held A teleconference call meeting was held to discuss the 2013 AST Demolition and soil sampling report which identified a historic release of Diesel Fuel at the site. Discussed and scoped additional Site Characterization required prior to a clean up plan. DEC requested groundwater samples and surface water sampling be included in a Site Characterization Work Plan for the Site. Discussed Site Intake and appropriate billing addresses for DEC cost recovery. Dennis Shepard
11/26/2013 Exposure Tracking Model Ranking Initial ranking with ETM completed for source area id: 79562 name: Former 4,000-Gallon Diesel AST Dennis Shepard
12/2/2014 Site Characterization Report Approved DEC approved the Site Characterization Sample Report, Site of Former AST, Lake Kotongan, Unalakleet, Alaska (September 2014). Dennis Shepard
4/3/2015 Cleanup Plan Approved DEC approved the Former AST Contaminated Soil Removal Workplan, Native Village of Unalakleet, Unalakleet, Alaska (April, 2015). Dennis Shepard
8/7/2015 Document, Report, or Work plan Review - other DEC approved the Landfarm Proposal and the Soil Removal and Sampling and Analysis Plan, Site of Former AST Lake Kotongan, Unalakleet, Alaska (February 24, 2015). Dennis Shepard
8/25/2016 Update or Other Action DEC approved a Addendum Landfarm Proposal, Native Village of Unalakleet, Unalakleet, Alaska, August 2016. The addendum reflects a change in the proposed location for the landfarm. The original landfarm footprint was to be located three miles north of Unalakleet off of North River Road. However, community members requested the landfarm location be changed due to proximity to residential areas. The new approved landfarm location is approximately 14-miles east of Unalakleet at the United States Airforce (USAF) Radio Relay Site at Site SS004 Area B. Dennis Shepard
10/25/2016 Update or Other Action A sheen on Kotongan Lake was observed in the Summer of 2015 and was reported to DEC after freeze up occurred. Monitoring of the pond occurred through Summer 2016 and the sheen did not return - only biogenic occurred. It is believed the sheen was the result of road oiling from vehicles and not associated with the buried pipeline. Joy Whitsel
9/12/2017 Site Characterization Workplan Approved DEC approved the Groundwater Monitoring Work Plan for Kotongan Lake Above Ground Storage Tank (AST). The purpose of work plan is to describe the methods and procedures to install monitoring wells and collect groundwater samples from the former AST site in Unalakleet, Alaska Joy Whitsel
9/12/2017 Site Characterization Workplan Approved DEC approved the Groundwater Monitoring Plan for the former AST located near Kotongan Lake, Unalakleet, Alaska. The work plan includes installation of two monitoring wells and collection of groundwater samples. Joy Whitsel
2/22/2018 Document, Report, or Work plan Review - other DEC reviewed the draft “NVU Former AST Report, Unalakleet NALEMP Kotongan Lake, Unalakleet, Alaska” dated December 2017 and provided comments on the report to the Native Village of Unalakleet on 22 FEB 2018. The report describes the: construction of a landfarm cell; excavation of 360 cubic yards of petroleum-contaminated soil; soil sampling; installation of two groundwater monitoring wells; and backfilling of the excavation at the site. The report indicates that petroleum-contaminated soil above DEC’s method two cleanup levels remains in place within the Tank Road roadbed, and at the soil/groundwater interface within the former tank footprint. Melinda Brunner
3/28/2018 Document, Report, or Work plan Review - other DEC provided evaluation of the Native Village of Unalakleet's (NVU) response to DEC's comments on the draft “NVU Former AST Report, Unalakleet NALEMP Kotongan Lake, Unalakleet, Alaska” dated December 2017 on March 28, 2018. Melinda Brunner
5/2/2018 Document, Report, or Work plan Review - other DEC reviewed the “Native Village of Unalakleet NALEMP CA Landfarm Treatment Year 1 Technical Memorandum, Draft” dated March 29, 2018. The memorandum describes the operation and maintenance of a soil landfarm outside Unalakleet, Alaska where 360 cubic yards of petroleum-contaminated soil excavated from the Unalakleet NALEMP Kotongan Lake AST site were spread, fertilized and tilled during 2017. DEC anticipates the Native Village of Unalakleet will sample the soil, and based on results of that sampling, continue forward with landfarm operations in accordance with the “Landfarm Proposal” approved by DEC on July 7, 2015 and the “Addendum Landfarm Proposal” approved by DEC on August 25, 2016. Comments on the draft document were provided to the Native Village of Unalakleet. Melinda Brunner
4/25/2019 Document, Report, or Work plan Review - other DEC received the Draft Remediation Report, Unalakleet, Alaska dated April 2019. Bri Clark
5/17/2019 Document, Report, or Work plan Review - other DEC provided comments on the Draft Remediation Report Unalakleet, Alaska, dated April 2019. Bri Clark
7/16/2019 Document, Report, or Work plan Review - other DEC provided review comments for the “Draft Site Characterization and Soil Excavation Work Plan, Former AST Site, Kotongan Lake, Native Village of Unalakleet, Unalakleet, Alaska, dated July 2019. The workplan describes soil borings to be completed to the west of Tank Road in Unalakleet, Alaska to help delineate the extent of contamination remaining in soil from the Kotongan Lake Aboveground Storage Tank (AST). The work plan includes the excavation and removal of 100 cubic yards of DRO contaminated soil. Dennis Shepard
6/5/2020 Document, Report, or Work plan Review - other DEC provided review comments for the Draft Site Characterization and Soil Delineation Report, Former AST Site, Kotongan Lake, Unalakleet, Alaska, May 2020. The report describes the approach, methods, and results for soil sampling conducted at the former 500,000-gallon aboveground storage tank (AST) site (ADEC Hazard ID#26159), near Kotongan Lake, Unalakleet, Alaska. The field activities described were conducted between September 8th and 13th, 2019. Dennis Shepard
9/16/2021 Document, Report, or Work plan Review - other DEC provided review comments for the Draft Delineation, Investigation and Groundwater Monitoring Program Work Plan, Kotongan Lake, Unalakleet, Alaska, September 2021. The work plan describes the approach and methods for soil and groundwater sampling to be conducted at the former 500,000-gallon aboveground storage tank (AST) site (ADEC Hazard ID#26159), near Kotongan Lake, Unalakleet, Alaska. Dennis Shepard
9/30/2021 Document, Report, or Work plan Review - other DEC approved the Final Delineation, Investigation and Groundwater Monitoring Program Work Plan, Kotongan Lake, Unalakleet, Alaska, September 2021. The work plan describes the approach and methods for soil and groundwater sampling to be conducted at the former 500,000-gallon aboveground storage tank (AST) site (ADEC Hazard ID#26159), near Kotongan Lake, Unalakleet, Alaska. Axl LeVan
10/22/2021 Meeting or Teleconference Held DEC had a meeting with Unalakleet Environmental Manager, USAF representative, and contractors regarding a proposed change to boring locations during the work associated with the "Final Delineation, Investigation and Groundwater Monitoring Program Work Plan, Kotongan Lake, Unalakleet, Alaska, September 2021." Atleast six borings planned for the historical pipeline, will be moved to the southern grid to increase delineation of the plume. DEC accepted the proposed deviation and support similar deviations as necessary based on drilling conditions. Axl LeVan
5/25/2022 Document, Report, or Work plan Review - other DEC received the "Draft Delineation, Investigation and Groundwater Sampling Report, Unalakleet, Alaska, April 2022" on 4/26/2022. The report describes the approach, methods, and results for soil and groundwater sampling conducted at the former 500,000-gallon aboveground storage tank. The primary purpose of this work was to determine the lateral and vertical extent of contamination and potential comingling with a historical gasoline spill (DEC Hazard ID #806, Site File Number 630.38.007). The report makes recommendations for steps going forward including further delineation of contamination and the removal of the gross DRO contamination on the site. Axl LeVan
7/5/2022 Document, Report, or Work plan Review - other DEC received the "Draft Addendum-Landfarm Treatment NVU Former AST Site, Unalakleet, Alaska, June 2022" on July 28, 2022. The Addendum outlines ChemTrack Alaska, Inc.’s (ChemTrack’s) approach for the 2022 field effort at the former 500,000-gallon aboveground storage tank (AST) site in Unalakleet, Alaska. The intent of this effort is to properly transport and remediate 500 cubic yards (CY) of grossly contaminated diesel impacted soil from the former 500,000-gallon AST site at the proposed landfarm location. This Project Plan is an addendum to the Final Site Characterization and Soil Excavation Work Plan Former AST Site, Kotongan Lake Unalakleet, Alaska ChemTrack, July 2019. DEC provided comments on the work plan addendum 7/5/2022. Axl LeVan
7/7/2022 Document, Report, or Work plan Review - other DEC received the response to comments for "Draft Delineation, Investigation and Groundwater Sampling Report, Unalakleet, Alaska, April 2022" on 6/27/2022. The majority of DEC comments were addressed and DEC provided further comments on 7/7/2022 for the submittal of a final document for review. Axl LeVan
7/13/2022 Document, Report, or Work plan Review - other DEC received the response to comments for "Draft Addendum-Landfarm Treatment NVU Former AST Site, Unalakleet, Alaska, June 2022" on 7/12/2022. The majority of DEC comments were addressed and DEC requested a final version of the document with additional information integrated. Axl LeVan
7/15/2022 Document, Report, or Work plan Review - other DEC approved the "Final Addendum-Landfarm Treatment NVU Former AST Site, Unalakleet, Alaska, July 2022" on 7/15/2022. All DEC comments were addressed and DEC approves the work plan for use. Axl LeVan
9/8/2022 Document, Report, or Work plan Review - other DEC approved the "Final Delineation, Investigation and Groundwater Sampling Report, Unalakleet, Alaska, September 2022" received on 9/2/2022. All DEC comments were addressed and integrated into the final document. The report describes the approach, methods, and results for soil and groundwater sampling conducted at the former 500,000-gallon aboveground storage tank. The primary purpose of this work was to determine the lateral and vertical extent of contamination and potential comingling with a historical gasoline spill (DEC Hazard ID #806, Site File Number 630.38.007). The report makes recommendations for steps going forward including further delineation of contamination and the removal of the gross DRO contamination on the site. Axl LeVan
6/20/2023 Document, Report, or Work plan Review - other DEC reviewed and provided comments on the "Draft Interim Corrective Action Report NVU Former AST Site, Unalakleet, Alaska, May 2023" received May 29, 2023. The document presents results from soil excavation, landfarm operations, and groundwater monitoring conducted in July and October 2022 at a former aboveground storage tank (AST) site near Kotongan Lake in Unalakleet. Axl LeVan
9/29/2023 Document, Report, or Work plan Review - other DEC reviewed and approved the "Final Interim Corrective Action Report NVU Former AST Site, Unalakleet, Alaska, September 2023" received September 29, 2023. Axl LeVan

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State of Alaska Department of Environmental Conservation

P.O. Box 111800
Juneau, AK 99811-1800
Phone: 907-465-5066
Fax: 907-465-5245
TDD: 800-770-8973
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