| Action Date |
Action |
Description |
DEC Staff |
| 10/17/2014 |
Underground Storage Tank Site Characterization or Assessment |
UST closure site characterization and assessment work underway. |
Paul Horwath |
| 10/17/2014 |
Leaking Underground Storage Tank Cleanup Initiated - Petroleum |
Contaminated soil excavated and stockpiled onsite. |
Paul Horwath |
| 10/22/2014 |
Document, Report, or Work plan Review - other |
Review and approval of a release investigation work plan and corrective action work plan. |
Paul Horwath |
| 10/23/2014 |
Site Characterization Workplan Approved |
Approved a release investigation work plan. |
Paul Horwath |
| 10/23/2014 |
Interim Removal Action Approved |
Approved work plans to excavate and transport contaminated soil to Anchorage for treatment/disposal, and install treatment system and GW monitoring wells. |
Paul Horwath |
| 10/23/2014 |
Offsite Soil or Groundwater Disposal Approved |
ADEC approval issued for offsite soil transport, treatment, and disposal. Soil transported to ASR in Anchorage. |
Paul Horwath |
| 10/23/2014 |
Cleanup Plan Approved |
Corrective action plan approved. |
Paul Horwath |
| 10/31/2014 |
Site Added to Database |
A new site has been added to the database |
Mitzi Read |
| 10/31/2014 |
Leaking Underground Storage Tank Release Confirmed - Petroleum |
LUST site created in CSP database for source area Tesoro Northstore #76, 79684 |
Mitzi Read |
| 12/1/2014 |
Potentially Responsible Party/State Interest Letter |
PRP letter issued to the Tesoro Refining and Marketing Company. |
Paul Horwath |
| 2/12/2015 |
Site Characterization Report Approved |
October 2014 UST Release Investigation Report - Final reviewed/approved. |
Paul Horwath |
| 2/18/2015 |
Exposure Tracking Model Ranking |
Initial ranking with ETM completed for source area id: 79684 name: Tesoro Northstore #76 |
Paul Horwath |
| 8/20/2015 |
Document, Report, or Work plan Review - other |
Review the February 2015 Monitoring Event Report, prepared by MWH, dated Final - August 2015. Some pretty high levels of benzene and GRO/DRO in MW-3 and MW-4. |
Paul Horwath |
| 10/9/2015 |
Document, Report, or Work plan Review - other |
Reviewed the June 2015 Monitoring Event Report, prepared by MWH, and dated September 2015. MWs 2, 3, and 4 exceed groundwater cleanup levels (GCLs). GRO concentrations in MW-2 indicate presence of LNAPL. Soil Vapor Extraction (SVE) system began operating in June, 2015. Based on the subsurface air flow rate and the BTEX concentrations reported in an air sample collected June 25, 2015, the SVE system was removing an estimated 58 lbs of BTEX per day - on June 25, 2015. A surface water sample collected for the wetland located to the SSE of the former UST systems detected xylenes (6.1 ug/L) at concentrations below Alaska Water Quality standards (10 ug/L TAH). |
Paul Horwath |
| 4/18/2016 |
Document, Report, or Work plan Review - other |
Review the January 2016 Monitoring Event Report. GRO/benzene concentrations remain high in MW-3. GRO >100mg/l indicate LNAPL in the GW at MW-3. |
Paul Horwath |
| 12/1/2016 |
Meeting or Teleconference Held |
Paul Horwath attended the ADEC/Tesoro Annual projects meeting held at the MWH office in Anchorage to review corrective action work accomplished in 2016, and to discuss the Corrective Action Work Plan for 2017. |
Paul Horwath |
| 12/8/2016 |
Document, Report, or Work plan Review - other |
Review MWH's October 2016 GW Monitoring Event Report and treatment systems operations report, dated Final - November 2016. The report indicates GW contaminant concentrations remain very persistent. A substantial organic peat deposit is present in the groundwater contaminant plume and this peat could be stubbornly retaining the hydrocarbons, in spite of treatment efforts. |
Paul Horwath |
| 4/4/2017 |
Document, Report, or Work plan Review - other |
Approve a work plan for a pilot test of an air sparge-type groundwater treatment system. |
Paul Horwath |
| 10/20/2017 |
Document, Report, or Work plan Review - other |
Review Stantec's April 2017 GW Monitoring Event and Biosparge Pilot Test Report. Send review comments to Stantec, for correction and resubmittal of an amended report. |
Paul Horwath |
| 12/7/2017 |
Meeting or Teleconference Held |
Meeting with Tesoro's Anne Duarte and Stantec staff at the offices of Stantec in Anchorage. Review work accomplished in 2017, and assessment and cleanup work proposed for 2018. |
Paul Horwath |
| 12/11/2017 |
Document, Report, or Work plan Review - other |
Reviewed Stantec's September 2017 Groundwater Monitoring Event Report, dated December, 2017.
High concentrations of contamination remains in the shallow perched groundwater at this site. A layer of naturally occurring peat is present in contact with the groundwater, complicating insitu groundwater treatment. |
Paul Horwath |
| 4/10/2018 |
Document, Report, or Work plan Review - other |
Reviewed Stantec's April 10, 2018, February 2018 groundwater monitoring report. Similar GW concentrations detected, as in prior sampling events. Petroleum contaminants persistent in groundwater. |
Paul Horwath |
| 4/10/2018 |
Document, Report, or Work plan Review - other |
Review Stantec's February 2018 Tesoro 2 Go Mart #76 Monitoring Event Report – Final. Stantec evaluating methods to improve efficiency of GW treatment system. |
Paul Horwath |
| 7/2/2019 |
Document, Report, or Work plan Review - other |
ADEC issued approval of a Stantec work plan to install a GW pump and treat treatment system pumping well. |
Paul Horwath |
| 7/26/2019 |
Document, Report, or Work plan Review - other |
ADEC issued approval of 2019 Work Plan for Task 3, Replace Bio-Sparge Treatment System with a Groundwater Pump and Treat System. |
Paul Horwath |
| 11/25/2019 |
Document, Report, or Work plan Review - other |
RW-1 has ben installed and will be plumbed in during the 1st 1/4 2020. A recirculation well will be added at the same time. Chemox treatment of groundwater will twice a year. |
Peter Campbell |
| 11/25/2019 |
Update or Other Action |
Approval to transport 2 drums of drill cuttings to NRC. |
Peter Campbell |
| 12/12/2019 |
Meeting or Teleconference Held |
Annual meeting to discuss site status and the next years work plan. |
Peter Campbell |
| 12/13/2019 |
Document, Report, or Work plan Review - other |
Review and approve the Corrective Action Work Plan for 2020. Tasks for 2020 will include gauging and sampling monitoring wells and the on site domestic drinking water well, completing the installation of the recirculation groundwater treatment system, and the operation of the chemical oxidation treatment system. |
Peter Campbell |
| 2/20/2020 |
Document, Report, or Work plan Review - other |
Review October 2019 Groundwater Monitoring Report. Biosparge system currently not operational and is being replaced. Will be operational in the early summer 2020. MW-3 showing the greatest level of impacts.
Undefined hydrocarbon peaks in MW-2 and MW-3, probably PAH compounds.
|
Peter Campbell |
| 2/21/2020 |
Document, Report, or Work plan Review - other |
Review July 2019 Groundwater Monitoring Report. |
Peter Campbell |
| 2/28/2020 |
Document, Report, or Work plan Review - other |
Review the April 2019 Monitoring Event Report |
Peter Campbell |
| 10/27/2020 |
Update or Other Action |
1. The third and fourth quarter monitoring events were completed. A level survey was completed to measure the current elevations of all of the on-site wells.
2. The submersible well pump and plumbing system was installed and activated in the new remediation/recirculation well RW 19-1. The well has been operating on a continuous basis at a pumping rate of approximately 8 gallons per minute for the past few months. We just completed the installation of heat trace lines and insulation on the well discharge lines. Plan to install the iMonnit controls so that we could operate this well pumping (recirculation) system on a full time yearly basis.
3. We completed 2 separate injections of Klozur One in the 3 remediation wells located under the existing store. |
Peter Campbell |
| 11/30/2020 |
Update or Other Action |
Remediation Well RW 19-1 was installed and a technical memorandum (April 27, 2020) was produced documenting the details. |
Peter Campbell |
| 1/27/2021 |
Document, Report, or Work plan Review - other |
Review the October 2020 monitoring report. Sampling trends indicate that the remediation system is having an effect. The site water supply well has not been impacted by hydrocarbons. |
Peter Campbell |
| 2/2/2021 |
Document, Report, or Work plan Review - other |
Reviewed the 2021 Corrective Action Plan. Site will be continued to be managed running the groundwater recirculation system with the injection of chemox treatment. |
Peter Campbell |
| 2/10/2021 |
Document, Report, or Work plan Review - other |
2021 Corrective Action Plan Approved |
Peter Campbell |
| 6/14/2021 |
Document, Report, or Work plan Review - other |
Review 3rd 1/4 2020 Groundwater Monitoring Report. Ground water level is down significantly. RW-19-1 installed and brought into service. |
Peter Campbell |
| 8/13/2021 |
Document, Report, or Work plan Review - other |
Reviewed March 2021 groundwater monitoring report. Remediation system operational. Groundwater flow direction matches historical pattern. |
Peter Campbell |
| 11/1/2021 |
Document, Report, or Work plan Review - other |
The 2nd quarter 2021 groundwater monitoring included: measuring the depth to groundwater; measuring intrinsic water quality parameters; and collecting groundwater samples from monitoring wells MW-01, MW-02, MW-03, MW-04 and remediation well RW19-1.
Results of the groundwater sampling showed that analytes detected above ADEC GCLs in the samples were: MW-3: Benzene, ethylbenzene, xylenes, gasoline range organics (GRO), diesel range organics (DRO), 1,2,4-trimethylbenzene (TMB) and 1,3,5-TMB. Well MW-4: Benzene.
The hydraulic gradient was 0.027 feet per foot toward the northeast. The groundwater gradient and flow direction are generally consistent with past monitoring events.
The operation of the groundwater “pump and treat” well (RW 19-1) was operating within normal range. The well pump was discharging approximately 1.4 gallons per minute into the three on-site treatment/remediation wells that are located within the footprint of the former underground storage tank (UST). The pumped groundwater is treated in-situ with a chemical oxidation injection process.
On July 28, 2021, Stantec completed groundwater remediation event that included the injection of chemical oxidation solution into the three treatment/remediation wells. The injection process involved the manual injection of a mixture of two 55-pound bags of Klozur One® product.
|
Peter Campbell |
| 12/3/2021 |
Document, Report, or Work plan Review - other |
Review and approve the 4th Quarter, October 2021 Groundwater Monitoring Event Report. The direction of groundwater flow may be altered from mounding of injected remediation water. Chemox treatments appear to be successful in reducing concentrations. |
Peter Campbell |
| 12/7/2021 |
Meeting or Teleconference Held |
2022 Corrective Action Plan meeting |
Peter Campbell |
| 12/9/2021 |
Document, Report, or Work plan Review - other |
2022 Corrective Action Plan ADEC Approval Letter |
Peter Campbell |
| 8/16/2022 |
Document, Report, or Work plan Review - other |
Groundwater flow consistent with past observations. Recovery well in operation at 2 gpm. Chemox solution added to system. |
Peter Campbell |
| 9/19/2022 |
Document, Report, or Work plan Review - other |
Review 2nd Q 2022 report. Monitoring wells 1, 2 & 3 continue a cleanup trend, apparent responding to Chemox treatment. MW-4 had an unusual increase in benzene, GRO and xylene for the past 2 sampling evets.
Recovery well 19-1, which is the treatment well also had unusual detections in 1,2,4-TMB, benzene and ethylbenzene. |
Peter Campbell |
| 11/29/2022 |
Long Term Monitoring Workplan or Report Review |
Review 4th Quarter 2022 Report. Pumps off during low groundwater from June 23 to July 20 to protect pump. GW direction consistent, gradient steeper. Pump rate went from 1 gpm to 2.5 gpm after well remediation. Lower sodium levels may reflect a longer interval between Chemox injections. |
Peter Campbell |
| 11/30/2022 |
Long Term Monitoring Workplan or Report Review |
Review August 2022 Monitoring Report. Chemox injected in RW-1, RW-2 and RW-3. Remediation pumps turned off from June 23 to July 20 because of a low water table due to a lack of precipitation in early and midsummer. Groundwater flow direction was more westerly than previous monitoring events, gradient similar to past events. Benzene is the primary remaining contaminant, with Ethylbenzene in MW-4 and naphthalene in MW-3 and MW-4. RW-2 did not take chemox as readily as RW-1 & RW-3.
|
Peter Campbell |
| 11/30/2022 |
Long Term Monitoring Workplan or Report Review |
Review and approve 3rd Quarter August 2022 Groundwater Monitoring Event Report |
Peter Campbell |
| 12/2/2022 |
Long Term Monitoring Workplan or Report Review |
Review the 2023 Corrective Action Work Plan. No significant changes for 2023. Benzene has been persistent in many of the wells as other hydrocarbon compounds have broken down. |
Peter Campbell |
| 12/6/2022 |
Meeting or Teleconference Held |
Annual meeting held to discuss 2022 work and plans for 2023. 2023 Corrective Action Plan Approved. |
Peter Campbell |
| 5/22/2023 |
Long Term Monitoring Workplan or Report Review |
Review the March 2023 Ground Water Monitoring Report. MW-3, an upgradient well has the highest level of contamination. Concentrations are increasing in MW-4. Recovery well RW-19 was cleaned of iron flocculant in the pump and discharge pipe. Chemox was added to three treatment wells.
|
Peter Campbell |
| 12/7/2023 |
Meeting or Teleconference Held |
Annual meeting to discuss site conditions and the 2024 Corrective Action Work Plan. Review the report and CAP. The CAP tables have incorrect data that will be revied based on a lab error. CAP 2024 ready for approval. |
Peter Campbell |
| 12/7/2023 |
Meeting or Teleconference Held |
Annual meeting held to discuss site progress and the 2024 Corrective Action Plan. Hydrocarbon levels are decreasing across the site. There have been significant modifications to the treatment system this year. There have been significant iron fouling issues at the site. |
Peter Campbell |
| 12/7/2023 |
Long Term Monitoring Workplan or Report Review |
2024 Corrective Action Work Plan - ADEC Approval |
Peter Campbell |
| 2/27/2024 |
Long Term Monitoring Workplan or Report Review |
MW-2, MW-3, MW-4 and RW 19-1 have hydrocarbons detected above cleanup levels.
In October 2022, the pump in RW-19 and the pump discharge pipe was cleaned. The well casing was purged to clean iron flocculant. The submersible pump was placed back into operation with an improved pumping rate of 2.5 gpm.
Monitoring well MW-4 has historically shown more contamination. However, results from this monitoring event show that petroleum contaminant concentrations have decreased in MW-4 since the Q1 sampling event.
|
Peter Campbell |
| 3/12/2024 |
Long Term Monitoring Workplan or Report Review |
Review 3rd Quarter 2023 Groundwater Monitoring Report. MW-1, MW-2, MW-3, MW-4 and RW 19-1 have hydrocarbons detected above cleanup levels. Monitoring well MW-4 has historically shown more contamination and has increased slightly from the last sampling event. |
Peter Campbell |
