Division of Spill Prevention and Response

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Site Report: Frontier Texaco (former Unocal - #5773) Chevron 30-6454


Site Name: Frontier Texaco (former Unocal - #5773) Chevron 30-6454
Address: 11301 Old Glenn Hwy.; , Eagle River, AK 99577
File Number: 2107.26.007
Hazard ID: 23579
Status: Cleanup Complete - Institutional Controls
Staff: Bill O'Connell, 9072693057 bill.oconnell@alaska.gov
Latitude: 61.322156
Longitude: -149.569712
Horizontal Datum:NAD83


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

Soil and groundwater petroleum hydrocarbon contamination from UST facility documented 1986 when 4 monitoring wells were installed at the site. Additional monitoring wells were installed in 1995. Groundwater is 17 to 19 feet below ground surface and flows towards the northwest. Six USTs, an oil/water separator, associated piping, and two hoists were removed in 1997. Soil (up to 10,300 mg/kg GRO, 55,900 mg/kg DRO, and 52.1 mg/kg benzene) and groundwater contamination was found at several locations. 450 cubic yards of contaminated soil was excavated and thermally treated. Remediation piping was installed when the excavations were backfilled and three new USTs were installed in 1997. Additional monitoring wells were installed in 2001. The soil vapor extraction system began operation in 2003. Operation of the remediation system and groundwater monitoring continue at this site. F.K.A. L35.08



Action Information

Action Date Action Description DEC Staff
6/28/1986 Underground Storage Tank Site Characterization or Assessment Soil borings and monitoring wells found soil and groundwater contamination at the site. Scott Pexton
10/21/1986 Release Investigation RZA's report summarizing subsurface petroleum hydrocarbon contamination at the site. Groundwater is 17 to 19 feet below ground surface and flows towards the northwest. Groundwater samples from monitoring wells MW-1 through MW-4 had petroleum hydrocarbon concentration ranging from 0.29 ppm to 0.09 ppm when sampled on 12/4/86. Groundwater sample taken on 12/8/86 from well MW-2 had 1.0 ppb toluene and 1.0 ppb xylene. Soil sample MW-4, S1 taken on 12/8/86 had 13 ppb xylene. * Not Assigned
6/27/1988 Site Added to Database * Not Assigned
6/27/1988 Leaking Underground Storage Tank Release Confirmed - Petroleum LUST Site created in CSP for source area ID 78067 Petroleum contaminant. * Not Assigned
6/28/1988 Leaking Underground Storage Tank Cleanup Initiated - Petroleum LCAU Date changed DB conversion * Not Assigned
6/9/1995 Leaking Underground Storage Tank Corrective Action Underway Reviewed and approved soil disposal plan. * Not Assigned
7/24/1995 Report or Workplan Review - Other Reviewed a release investigation report. Additional monitoring wells were installed. * Not Assigned
4/30/1997 Report or Workplan Review - Other Six USTs, an oil/water separator, associated piping, and two hoists were removed in 1997. Soil (up to 10,300 mg/kg GRO, 55,900 mg/kg DRO, and 52.1 mg/kg benzene) and groundwater contamination was found at several locations. 450 cubic yards of contaminated soil was excavated and thermally treated. Remediation piping was installed when the excavations were backfilled and three new USTs were installed in 1997. Robert Weimer
11/20/1997 Update or Other Action ADEC sends Notification of Intent to Cost Recover Letter to Current Owner: MILCO INC. * Not Assigned
1/9/1998 Update or Other Action ADEC requests further release investigation and groundwater monitoring. * Not Assigned
1/11/2001 Update or Other Action ADEC conditionally approves release investigation workplan. Robert Weimer
10/11/2002 Update or Other Action Approved financial assistance program corrective action plan. Robert Weimer
10/16/2002 Report or Workplan Review - Other October 16, 2002 groundwater monitoring event. Up to .42 mg/l RRO in the groundwater. Concentrations appear stable. Robert Weimer
1/30/2003 Report or Workplan Review - Other January 30, 2003 groundwater sampling. Up to <0.09 mg/l GRO, <0.568 mg/l DRO, <1.14 mg/l RRO, and 0.00311 mg/l benzene in groundwater. Contamination levels increased in 5 of the 7 monitoring wells sampled. Groundwater flow direction is to the northwest. Depth to groundwater is 18.07 to 19.40 feet below ground surface. Robert Weimer
3/21/2003 Update or Other Action Approved corrective action plan to continue to operate soil vapor extraction/venting remediation system. Robert Weimer
4/11/2003 Report or Workplan Review - Other April 11, 2003 groundwater sampling. Up to <0.01 mg/l GRO, <0.11 mg/l DRO, <0.21 mg/l RRO, and <0.0005 mg/l benzene in groundwater. Contamination levels decreased in 5 of the 5 monitoring wells sampled. Groundwater flow direction is to the northwest. Depth to groundwater is 18.41 to 19.75 feet below ground surface. Robert Weimer
7/8/2003 Report or Workplan Review - Other July 8, 2003 groundwater sampling. Up to <0.01 mg/l GRO, <0.11 mg/l DRO, <0.21 mg/l RRO, and <0.0005 mg/l benzene in groundwater. Contamination levels increased in 0 of the 7 monitoring wells sampled. Groundwater flow direction is to the northwest. Depth to groundwater is 18.20 to 19.49 feet below ground surface. Robert Weimer
9/24/2003 Site Characterization Report Approved September 24, 2003 groundwater sampling. Up to <0.01 mg/l GRO, <0.11 mg/l DRO, <0.21 mg/l RRO, and <0.0005 mg/l benzene in groundwater. Contamination concentrations increased in 0 of the 7 monitoring wells sampled. Groundwater flow direction is to the northwest. Depth to groundwater is 18.74 to 20.07 feet below ground surface. Robert Weimer
9/25/2003 Update or Other Action ADEC staff changed from Weimer to Harwood Dennis Harwood
5/26/2004 Update or Other Action Letter sent to Milco, Inc. with reminder of grant termination date of June 30, 2004 for grant #15248333. Scott Pexton
8/23/2004 Update or Other Action Sent letter to Gerald Millette, President of Milco, Inc. requesting information about his intentions to complete corrective actions and groundwater monitoring. Site transferred from Dennis Harwood to Jim Frechione. Scott Pexton
10/6/2004 Update or Other Action ADEC staff changed from Frechione to Weimer Robert Weimer
12/2/2005 Update or Other Action Have not received reports on site monitoring and operation of the remediation system. Robert Weimer
8/24/2006 Update or Other Action RP's consultant called to say that they were preparing a workplan for groundwater monitoring and remediation of the site. Robert Weimer
6/2/2008 Exposure Tracking Model Ranking Site ranked on the new Exposure Tracking Model (ETM). The ETM is a new site ranking system that looks at, based on available data, the potential exposure pathways for the contamination remaining at the site. Robert Weimer
10/24/2008 Update or Other Action ADEC requests a groundwater monitoring event before the end of 2008. All monitoring wells are to be sampled for BTEX, GRO, DRO, and RRO. Monitoring wells 2,3, and 7 to be sampled for HVOCs in addition. Robert Weimer
2/25/2009 Meeting or Teleconference Held Meeting with Chevron and their consultants. They are to conduct an evaluation of indoor air at this site. Chevron is to contact current owner to get site access to conduct quarterly groundwater monitoring (all monitoring wells for BTEX/GRO/DRO/RRO, plus HVOC's in monitoring wells MW2, MW3, and MW7) and operation/monitoring of the remediation system. Robert Weimer
6/4/2009 Meeting or Teleconference Held Discussed site status with RPs consultant (CRA). Could only sample monitoring wells MW2/5/7, these monitoring wells need to have their vaults replaced. MW3&6 appear to have been abandoned, and MW4 is obstructed. The soil vapor extraction system is currently operating on a pulsed system, but needs safety upgrades. CRA will provide recommendations on which wells should be abandoned and which wells should be replaced. Robert Weimer
6/17/2009 Report or Workplan Review - Other ADEC approves treatment of one drum of contaminated purge water. Robert Weimer
10/12/2009 Site Characterization Report Approved May 6, 2009 groundwater sampling. Up to 0.014 mg/l GRO, <0.11 mg/l DRO, <0.21 mg/l RRO, and <0.0005 mg/l benzene in groundwater. Contamination concentrations increased in 1 of the 4 monitoring wells sampled. Groundwater flow direction is to the northwest. Depth to groundwater is 19.25 to 20.60 feet below ground surface. Robert Weimer
10/26/2009 Report or Workplan Review - Other ADEC approves request for treatment of one drum of monitoring well purge water. Robert Weimer
2/1/2010 Site Characterization Report Approved September 14, 2009 groundwater sampling. Up to <0.050 mg/l GRO, <0.11 mg/l DRO, <0.21 mg/l RRO, <0.0005 mg/l MTBE, and <0.0005 mg/l benzene in groundwater. Contamination concentrations stable in all 3 of the monitoring wells sampled. Groundwater flow direction is to the northwest. Depth to groundwater is 19.25 to 20.34 feet below ground surface. Robert Weimer
3/11/2010 Meeting or Teleconference Held Meeting with Chevron and their consultants on 3/10/10. Chevron will submit a workplan for confirmation samples in 2010. Based on the results the SVE system will be upgraded and restarted or site clusure will be requested. We discussed that groundwater samples for volatiles should not be collected with bailers or peristaltic pumps due to the loss of volatiles, Chevron is to provide a workplan specifying how groundwater samples will be collected in the future. Robert Weimer
4/14/2010 Site Characterization Report Approved DEC review of 2/25/10 Vapor Intrusion Evaluation. Occupied buildings identified near where past soil sampling identified volatile contamination remaining (up to 10,300 mg/kg GRO, 55,900 mg/kg DRO, and 52.1 mg/kg benzene). The groundwater at 18 to 20 feet below ground surface has been below cleanup levels during recent monitoring events. Based on the results of confirmation soil sampling to be conducted in 2011, further vapor intrusion site work may be required. Robert Weimer
5/20/2010 Update or Other Action Approved, until further notice, no-purge groundwater sampling at this site. Robert Weimer
6/17/2010 Site Visit Site visit to observe ground water sampling using no purge strategy and hydra sleeve sampling equipment. Brenton Porter
2/17/2011 Site Characterization Report Approved June 17, 2010 groundwater sampling. Up to <0.05 mg/l GRO, <0.0005 mg/l MTBE, and <0.0005 mg/l benzene in groundwater. Contamination concentrations stable in all 3 of the monitoring wells sampled. Monitoring well MW4 was full of sediment and not sampled. Groundwater flow direction is to the northwest. Depth to groundwater is 18.68 to 19.70 feet below ground surface. Robert Weimer
3/2/2011 Report or Workplan Review - Other ADEC approves temporary storage of any purgewater generated in 2011 at the secure area at 1441 C Street. Robert Weimer
4/25/2011 Site Characterization Report Approved November 14, 2010 groundwater sampling. Up to <0.01 mg/l GRO, <0.0005 mg/l MTBE, and <0.0005 mg/l benzene in groundwater. Contamination levels stable in all 3 of the monitoring wells sampled. Monitoring well MW4 was full of sediment and not sampled. Groundwater flow direction is to the southwest. Depth to groundwater is 19.48 to 20.72 feet below ground surface. Robert Weimer
5/9/2011 Site Characterization Workplan Approved ADEC conditionally approves the “Revised Site Assessment Workplan” from CRA for this site. The workplan proposes to install one replacement monitoring well, and to collect confirmation soil samples from 10 soil borings at the above referenced site. The workplan is approved with the following modifications: 1. Confirmation samples collected in previously excavated areas are to be collected from native (non-backfilled) soil at about 1 foot below the previous sample depth that exceeded cleanup levels at the base of the excavation, the highest field screening depth, and the soil/water interface. 2. Confirmation samples collected in other areas are to be collected from native (non-backfilled) soil at the same depth that samples were previously collected that exceeded cleanup levels, the highest field screening depth, and the soil/water interface. 3. Add EDB and 1,2-DCA analysis to all analytical samples collected in boring SVP1. 4. Add EDB and 1,2-DCA analysis to the most likely contaminated one sample collected from the used oil tank, the most likely one contaminated sample from MW1, the most likely one contaminated sample from B4MWR, and the most likely one contaminated sample from the B7MW locations. 5. PAH analysis is only requested in 10% of the analytical samples, with a minimum of 1 per source area (Heating Oil tank, Used Oil tank, near the USTs, and near the dispenser island). They are to be collected at the location of most likely contamination for each source area. 6. The following proposed (8) boring locations may be deleted: SVP3, B2MW, north of the used oil tank, B6MW, B1MW, SVP2, SVP4, and north of the USTs. 7. The following (6) boring locations are requested: SVP1, MW1, B4MWR, at the used oil tank, at the heating oil tank, and B7MW. 8. The following proposed (1) monitoring well location may be deleted: B4MWR. 9. The following (3) boring locations are requested to be completed as monitoring wells: SVP1, MW1, and at the used oil tank. Robert Weimer
5/20/2011 Update or Other Action ADEC approves request to transport super sacks/drums of drill cuttings and vacuum truck pre-drilling soil from Chevron 30-6454 to 1441 C Street for temporary storage. ADEC requested that the total volume of soil be provided once delivery has been completed. Robert Weimer
5/20/2011 Report or Workplan Review - Other ADEC approves request to transport drums of decontamination and development water from Chevron 30-6454 to 1441 C Street for temporary storage. ADEC requested that the total number of drums be provided once delivery has been completed. Robert Weimer
6/2/2011 Update or Other Action ADEC receives documentation that one drum of decontamination and development water and 7 drums plus 5 super sacks of contaminated drill cuttings from Chevron 30-6454 was transported to 1441 C Street for temporary storage. Robert Weimer
7/26/2011 Offsite Soil or Groundwater Disposal Approved ADEC approves treatment of contaminated purge water. Robert Weimer
7/28/2011 Offsite Soil or Groundwater Disposal Approved Approved request for thermal treatment of 7 drums and 5 super sacks of contaminated soil generated during the site investigation work in the summer of 2011. Robert Weimer
7/28/2011 Offsite Soil or Groundwater Disposal Approved ADEC approves treatment of contaminated decon water. Robert Weimer
8/16/2011 Report or Workplan Review - Other ADEC approves request to purge monitoring wells prior to sampling. Purging and sampling will be conducted using a bladder pump. Robert Weimer
10/31/2011 Report or Workplan Review - Other DEC approves the September 9, 2011 Monitoring Well and Conduit Decommissioning Workplan for Chevron Site 30-6454, ADEC File ID: 2107.26.007. The work plan proposes to decommission monitoring well MW-3 and an unknown schedule 40 PVC pipe located in the northwest corner of the property. Robert Weimer
11/21/2011 Offsite Soil or Groundwater Disposal Approved ADEC approves treatment of contaminated purge water Robert Weimer
2/3/2012 Site Characterization Report Approved June 9, 2011 groundwater sampling. Up to 0.016 mg/l GRO, <0.0005 mg/l MTBE, and <0.0005 mg/l benzene in groundwater. Contamination concentrations increased in 1 of the 6 monitoring wells sampled. Monitoring well MW4 was replaced with MW10. Groundwater flow direction is to the southwest. Depth to groundwater is 18.80 to 20.50 feet below ground surface. A bladder pump was used to collect the groundwater samples. Report approved. Robert Weimer
7/31/2012 Report or Workplan Review - Other DEC receives documentation that monitoring well MW-3 and an unknown schedule 40 PVC pipe located in the northwest corner of the property were decommissioned on 11/2/2011. The unknown pipe is throught to be former monitoring well MW-1. Robert Weimer
8/17/2012 Offsite Soil or Groundwater Disposal Approved ADEC approves offsite treatment of contaminated purge water. Robert Weimer
11/5/2012 Site Characterization Report Approved August 24, 2011 groundwater sampling. Up to <0.010 mg/l GRO, <0.0005 mg/l MTBE, and <0.0005 mg/l benzene in groundwater. Contamination concentrations increased in none of the 6 monitoring wells sampled. Monitoring well MW4 was replaced with MW10. Groundwater flow direction is to the west. Depth to groundwater is 18.52 to 20.21 feet below ground surface. A bladder pump was used to collect the groundwater samples. Report approved. Robert Weimer
11/28/2012 Offsite Soil or Groundwater Disposal Approved ADEC approves offsite treatment of contaminated purge water. Robert Weimer
12/27/2012 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 78067 1986/1997 contamination. Bill O'Connell
12/28/2012 Report or Workplan Review - Other Reviewed Site Assessment Report and Cleanup Complete with Institutional Controls Request submitted on November 1, 2011. Six soil borings were advanced in 2011 and three of the borings were completed as monitoring wells. Soil borings were placed in areas noted be contaminated based on the results of the 1997 UST Closure Assessment including the dispenser area and former waste oil tank area. Soil samples collected from borings contained GRO up to 340 mg/kg at 5 feet bgs at the former dispenser area and DRO at 420 mg/kg in the same sample. No other soil samples contained contaminants above cleanup levels and groundwater samples collected from the newly installed wells did not contain contaminants above cleanup levels. Bill O'Connell
1/3/2013 Cleanup Complete Determination Issued The Alaska Department of Environmental Conservation, Contaminated Sites Program (ADEC) has completed a review of the environmental records associated with the Frontier Texaco (Former Unocal #5773) located at 11301 Old Glenn Highway in Eagle River, Alaska. Based on the information provided to date, it has been determined that the contaminant concentrations remaining on site do not pose an unacceptable risk to human health or the environment and no further action is required as long as the site is in compliance with established institutional controls (ICs) Bill O'Connell
2/27/2013 Meeting or Teleconference Held Meeting with Chevron and their consultants on 2/26/13. Chevron proposes to decommission the , monitoring wells, well points, and surface portions of the remediation system by July 31, 2013. Robert Weimer
6/28/2013 Report or Workplan Review - Other Reviewed work plan for monitoring well and remediation system decommissioning. Monitoring wells will be filled with bentonite and the upper blank casing will be removed, soil vapor probes will be filled with bentonite and then gravel, and the remediation system components will be filled with bentonite and cut off at the surface. The surface will be repaired with asphalt or concrete as appropriate. Horizontal components that do not contact groundwater will be left in place and cut off at the surface. Bill O'Connell
7/5/2013 Report or Workplan Review - Other Reviewed Monitoring Well and Remediation System Decommissioning work plan. Monitoring wells, SVE wells and soil vapor probes will be filled with bentonite to within 1 foot of the surface and the upper blank casing will be removed. Horizontal piping will be left in place. Bill O'Connell
1/2/2014 Report or Workplan Review - Other Monitoring Wells B2MW, B5MW, B7MW, B8MW, B9MW,and B10MW were decommissioned by removing the top 5 feet of casing and filling the remaining borehole with bentonite. Soil-vapor probes SVP1 through SVP4 and extraction well VEW-1 could not be located and are presumed to have been destroyed. Remediation system piping was decommissioned by cutting the piping off six inches bgs and filling with bentonite. Bill O'Connell
8/7/2015 Update or Other Action This file has been archived at Alaska Archive Barcode: 587286 Box 353 Susan Carberry

Contaminant Information

Name Level Description Media Comments
GRO Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation Soil
DRO Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation Soil
Benzene Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation Soil


Control Type

Type Details
Signed CS Determination


Requirements

Description Details
Advance approval required to transport soil or groundwater off-site.
Groundwater Use Restrictions Wells may only be installed with ADEC approval