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Site Report: ADOT&PF Gustavus Airport Sitewide PFAS


Site Name: ADOT&PF Gustavus Airport Sitewide PFAS
Address: Gustavus Airport, Gustavus, AK 99826
File Number: 1507.38.017
Hazard ID: 26904
Status: Active
Staff: Danielle Duncan, 9074655207 danielle.duncan@alaska.gov
Latitude: 58.422636
Longitude: -135.700232
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

The Alaska Department of Transportation and Public Facilities (ADOT&PF) detected two per and polyfluoroalkyl substances (PFAS) compounds perooctanesulfonic acid (PFOS) and Perfluorooctanoic acid (PFOA) in groundwater at two public water system wells near the airport in Gustavus in July 2018. Concentrations of PFOS exceeded the EPA's lifetime health advisory (LHA) levels in public water system ID AK 2111476 known as “Gustavus Airport.” Concentrations of PFOS and PFOA were below the Lifetime Health Advisory (LHA) in public water system ID AK 2130596 known as “Gustavus Water System” that provides water to the National Park Service housing and also to the Gustavus School. The contaminants are believed to have originated from the historic use of Aqueous Film Forming Foam (AFFF) at various locations at the Gustavus Airport. Investigation and public outreach are on-going. DOT&PF is working with an environmental consulting firm, Shannon & Wilson, Inc., and the Alaska Department of Environmental Conservation (DEC) to identify and sample private water wells that may have been affected. Water is being provided for well owners with PFAS (sum of five PFAS compounds) greater than or equal to 65 parts-per-trillion. For more information visit the ADOT&PF Gustavus webpage: http://dot.alaska.gov/sereg/GST-AIP_PFA/index.shtml

Action Information

Action Date Action Description DEC Staff
8/14/2018 Site Added to Database A new site has been added to the database Mitzi Read
8/24/2018 Public Notice A public information meeting + Q&A about PFAS in the groundwater at the Gustavus Airport and a community well will be held at the Gustavus Library on Monday, August 27, 2018 at 5:30-7:00 pm. The Alaska Departments of Transportation, Environmental Conservation, Health and Social Services, and Administration will provide information. Independent environmental consulting firm, Shannon & Wilson, will attend to schedule sampling times for properties south of the airport. More info at www.alaska.gov/go/C732. Danielle Duncan
9/6/2018 Update or Other Action Shannon and Wilson has sampled 44 groundwater wells, the two wells previously sampled, and 3 surface water locations in the area for 6 PFAS compounds. A rush on the analysis was requested for 10 samples and the other results will follow. Danielle Duncan
9/18/2018 Potentially Responsible Party/State Interest Letter Sent today~ Danielle Duncan
9/21/2018 Report or Workplan Review - Other Shannon & Wilson (S&W) has completed the first round of PFAS groundwater contamination delineation. PFAS discovered in several wells on the Gustavus Airport property and three private wells off property are reported in concentrations above DEC action levels (65 parts-per-trillion (sum of five PFAS compounds)). Concentrations at most private wells and the well which serves the National Park Service water system are below DEC action levels. S&W has expanded the sampling area to wells east and west of the airport. Water is being provided for people whose wells exceed the action level. For more information visit the ADOT&PF Gustavus webpage: http://dot.alaska.gov/sereg/GST-AIP_PFA/index.shtml Danielle Duncan
9/21/2018 Exposure Tracking Model Ranking Initial ranking with ETM completed for source area id: 80270 name: ADOT&PF Gustavus Airport Sitewide PFAS Danielle Duncan
10/23/2018 Report or Workplan Review - Other The second PFAS sampling event from areas east and west of the initial investigation were received. There are a total of four groundwater/drinking water wells on the airport property and 12 off-airport property with PFAS levels greater than the 65 ppt action level. DOT has provided bottled water to the affected property owners. Further sampling is going to occur in areas west across Salmon River (Area 6) and south (Area 7) of the current sampling area. The DOT Gustavus Airport PFAS website has been updated with a sampling map. In addition, a second public meeting will be held at the Gustavus School on October 30, 2018 from 5 to 6:30 pm. http://dot.alaska.gov/sereg/GST-AIP_PFA/index.shtml Danielle Duncan
10/30/2018 Meeting or Teleconference Held The second public meeting was held in Gustavus by members of the DEC, DOT, HSS, DOA, and ATSDR to present the latest data, listen to the community's concerns, answer questions, and provide health and regulatory information. Danielle Duncan
11/26/2018 Update or Other Action Sampling was completed west across Salmon River (Area 6) and south (Area 7) of the current sampling area. The results found only one new exceedance of the ADEC Action Level located within the original search area. Shannon & Wilson, Inc. doesn’t plan to expand their sampling area any further as the plume is delineated at this time. As they move more south the most prominent compound is PFHxS. This compound is typically smaller and moves faster than other PFAS compounds which is why it’s most prevalent closer to the edge of the plume. Shannon & Wilson clarified that we may have only defined the plume within the shallow drinking-water zone. Which means the contamination will need to be further defined in deeper aquifers for the purposes of site characterization through different depths of monitoring wells. BARR Engineering, Shannon & Wilson and Risk Management are working together to determine what the best long-term solution is for this community. Residents will continue to receive alternate water until a long-term solution is in place. Danielle Duncan
12/20/2018 Update or Other Action Per S&W, the Gustavus Community Garden well (PW-430) was sampled during the last sampling event and was non-detect across the board for the six PFAS analytes. Danielle Duncan
12/26/2018 Update or Other Action The DOT is working on getting a new contract in place to continue characterization work. Danielle Duncan
2/15/2019 Update or Other Action The DOT is planning on doing some improvements to the airport in the next year or two that were planned prior to the discovery of PFAS contamination. Danielle Duncan
2/26/2019 Update or Other Action Per the DOT, the contract for site work is in the finalization phases and was awaiting signatures. Danielle Duncan
3/14/2019 Update or Other Action The first round of quarterly groundwater monitoring for wells having concentrations greater than or equal to 35 parts-per-trillion (ppt) has been completed. Twenty drinking water wells were sampled last week as part of this effort. An additional eight wells were sampled within 500 feet of the quarterly monitored wells as a step-out effort. Two surface water samples were also collected from Glen's Ditch where the firetrucks collect water. The ADEC should receive a finalized copy of the report to review in the future. Danielle Duncan
3/22/2019 Report or Workplan Review - Other The surface water PFAS results for Mt View Rd creek and the gravel pits were both non-detect. The sampling was not part of the characterization effort - rather screening for a location to fill the fire truck. Danielle Duncan
3/28/2019 Report or Workplan Review - Other Received, reviewed, and provided comments on the Summary Report August 2018 to November 2018 Private Well Sampling this date. Waiting for a revised report. Danielle Duncan
3/28/2019 Update or Other Action Rec'd the March 2019 sampling results. The results (PFAS 6 compounds) for 26 samples (including private drinking water wells) were reported. There are no new exceedances but there were large decreases for 3 wells and 1 well had a large increase. Several scheduled locations were not sampled due to refusal by owner or winterized properties. The maximum sum of 5 PFAS concentration reported was 6,900 nanograms per liter (ppt). Danielle Duncan
3/29/2019 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 80270 ADOT&PF Gustavus Airport Sitewide PFAS. Danielle Duncan
5/6/2019 Site Characterization Report Approved Approved the Summary Report August 2018 to November 2018 Private Well Sampling Gustavus, Alaska this date. A total of 120 private wells were identified and 101 of these were sampled for PFAS at TestAmerica using their method WS-LC-0025 reporting six PFAS: PFOS, PFOA, PFHpA, PFNA, PFBS, and PFHxS. Of these, 18 exceeded the action level. The drinking water wells PFAS contamination is dominated by PFOS having concentrations up to 5,500 µg/L. PFHxS is the second highest contributor to the contamination having a maximum detected concentration of 1,900 µg/L. Alternative drinking water was provided to those well owners who had sum of five PFAS results above the action level. Five surface water samples were collected from various locations including sloughs, excavations, and drainage ditches and analyzed for PFAS. The results found PFAS above the action level on the east and southwest ends of the runway. The surface water contamination was also dominated by PFOS and PFHxS. According to the report, the ADOT&PF is exploring various long-term options including, but not limited to POE systems. Planned future work includes continuing the well search as needed, quarterly sampling in March 2019 and quarterly though 2019 (according to the proposed and approved well monitoring network), and the preparation of a site characterization work plan for the airport. Danielle Duncan
6/3/2019 Update or Other Action Per the DOT: Residential monitoring: Shannon & Wilson and DOT&PF are working to get one work plan created for all the airports and issue addendums to add airports impacted by PFAS as they are identified. The long-term monitoring plans will be part of this. We have not identified a funding source for this work yet. Seeing how it’s the end of the fiscal year this will most likely take place after July 1. S&W will send the quarterly monitoring information once she has it finalized. The contract was and funding source was just finalized late Friday afternoon for this work. Site characterization: The work plan has been drafted I should receive a copy for review soon. Filtration Systems: S&W said that the Gustavus Inn filtration system is installed and follow up testing will take place toward the end of the week or beginning of next week. There are no other updates to date regarding any of the other filtration systems. Also, per the DOT, doing the following work in the near future: Collecting pre- and post-treatment samples from the newly installed Gustavus Inn POET system. This is the first of the quarterly set of samples. They will be quarterly for the first year in order to conduct a full-scale pilot study on the system. Collecting a few garden soil samples from the Gustavus Inn. This is not part of site characterization activities and is being sampled as part of the claims process. Quarterly sampling of from Category 1 and 2 private wells (indoor plumbing) with a sum of PFOS/PFOA concentration greater than 35 ppt (sampling criteria). In the absence of monitoring criteria from ADEC (the updated Tech memo did not address this), we used the previously-proposed criteria, but switched out sum of 5 for sum of PFOS/PFOA. Additionally, nearby wells within 500 feet of a well meeting the sampling criteria will also be sampled. There are 30 wells that fit into these categories. Also part of this is sampling is two newly-installed wells in Gustavus. Both are in an area where it is likely their results will be greater than the action levels. One is the new Gustavus Community Center being built across the street from the Gustavus Inn. Danielle Duncan
6/24/2019 Report or Workplan Review - Other Reviewed and provided comments on the June 2019 Site Characterization Work Plan, however, the work plan is likely going out for public comment and as a result, there may be modifications to the work plan that will require reviewing. Danielle Duncan
7/3/2019 Update or Other Action The Gustavus Inn has been outfitted with a point-of-entry system and as a result, the DOT and DOA are no longer providing alternative drinking water and the ADEC has concurred. Danielle Duncan
7/13/2019 Update or Other Action Quarterly residential groundwater monitoring was completed for PFOS and PFOA only per the revised PFAS memo. Per S&W, "there are six locations that no longer appear to be exceedances based on the changes in the sampling guidelines. We are adding disclaimers to their results notification letters to notify them that they will still be eligible for a long-term solution based on their previous results. These locations will also continue to receive temporary alternative water." Danielle Duncan
8/5/2019 Site Characterization Workplan Approved Approved the Work Plan – Revision 1, Gustavus Airport PFAS Site Characterization this date. Soil, groundwater, surface soil, and sediment samples will be collected from various sites on and off airport property and analyzed for PFOS and PFOA. The work plan is available in the attachments section. Danielle Duncan
8/5/2019 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 80270 ADOT&PF Gustavus Airport Sitewide PFAS. Danielle Duncan

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