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Site Report: Peters Creek Chevron

Site Name: Peters Creek Chevron
Address: 20808 Bill Stephens Drive, Chugiak, AK 99567
File Number: 2106.26.015
Hazard ID: 26123
Status: Cleanup Complete - Institutional Controls
Staff: Michael Hooper, 9074515174 michael.hooper@alaska.gov
Latitude: 61.408098
Longitude: -149.451832
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

Petroleum-contaminated soil was discovered on September 15, 2013 around sumps for regulated underground storage tanks #1 (10,000-gallon - gasoline) and #2 (2A and 2B) (12,000-gallon dual compartment: 6,000-gallon - supreme gasoline & 6,000-gallon - diesel). Sumps were found to be out of compliance during a July 3, 2013 inspection by the IPP Program. On September 18, 2013 about 5 cubic yards of contaminated soil was removed at the gasoline tank sump (tank 1) and stockpiled at the site on the north side of the building. One sample was collected from the stockpile had 1,510 mg/kg GRO, 4.53 mg/kg naphthalene, and 3.63 mg/kg benzene. One sample was collected from the excavation had 5,390 mg/kg GRO, and 26.6 mg/kg benzene. Also on September 18, 2013 an additional 5 cubic yards of contaminated soil was removed at the diesel/supreme gasoline tank sump (tank 2) and stockpiled at the site on the north side of the building. One sample was collected from the stockpile had 66.7 mg/kg DRO, 9.47 mg/kg GRO, and 0.0656 mg/kg benzene. One sample was collected from the excavation had 7.91 mg/kg GRO, non-detect (<21.8 mg/kg) DRO, non-detect (<54.6 mg/kg) RRO, non-detect (<0.0115 mg/kg) PAHs, and 0.078 mg/kg benzene. On March 2014 four soil samples plus one duplicate were collected from four soil borings (one soil boring SB-4, had no analytical samples collected) drilled on the property. Soil boring SB-1 was drilled to 20 feet below ground surface (bgs) near the on-property septic leach field had no detectable petroleum. Soil boring SB-2 was drilled to 39 feet bgs near the current regulated underground storage tanks had a petroleum odors from 2.5 to the base of the boring at 39 feet bgs. In SB-2: 5,460 mg/kg GRO, 101 mg/kg DRO, non-detect (<21.3 mg/kg RRO), 123 mg/kg benzene, and 3.81 mg/kg lead in the analytical soil sample collected at 12.5 bgs. In SB-2: 55.2 mg/kg GRO, non-detect (<21.3 mg/kg) DRO, non-detect (<21.3 mg/kg) RRO, 2.6 mg/kg benzene, and 8.54 mg/kg lead in the analytical soil sample collected at 39 bgs. Soil boring SB-3 was drilled to 15 feet bgs near the location of the former underground storage tanks, which is about 100 feet to the northeast of the current undergound storage tanks, had a petroleum odors from 0.0 to the base of the boring at 15 feet bgs. In SB-3: 1,750 mg/kg GRO, 956 mg/kg DRO, non-detect (<20.8 mg/kg) RRO, 6.39 mg/kg benzene, and 4.61 mg/kg lead in the analytical soil sample collected at 15 bgs. On June 2014 a release investigation work plan is submitted and approved. The plan proposes to sample 9 soil boring to help define the nature and extent of the contamination identified near soil borings SB-2 and SB-3. If groundwater is encountered at least one boring per area will be completed as a monitoring well, a water well search is to be conducted in a quarter mile radius, and all water wells within 500 feet will be sampled. On August 2014 three monitoring wells were installed near the current location of the tanks. One of the monitoring wells was installed near the tanks and the other two in the estimated downgradient direction. Based on elevated field readings at the soil/water interface soil samples were collected during the installation of the monitoring wells. Groundwater was encountered at 139.5 feet below ground surface. On August 8, 2014 while not measurable with the oil/water interface probe there appears to be a thin layer of gasoline product in all three monitoring wells, the groundwater samples will be run in the lab to compare concentrations. On October 2014 a drinking water well survey was conducted in a 1/4 mile radius of the gas station property. The survey identified 77 active water wells with 1/4 mile and recommended water sampling at 10 of them for BTEX by EPA Method 524.2. The report identified that there may be some additional drinking water wells in the area on lots not currently in well databases and they plan to conduct additional field surveys and/or telephone surveys of those lots. Based on the survey and drinking water sample results they may recommend additional water wells to be sampled. Also on October 2014 three additional soil borings were sampled and one was completed as a monitoring well. Between December 30, 2014 and February 19, 2015 VOC (EPA Method 524.2) water samples were collected from 5 nearby drinking water wells located at 20727 Oberg Road, 22733 Friendship Lane, 20707 Oberg Road, 20912 Four Wheel Drive, and 20640 Chapel Road. All of the drinking water samples were non-detect. On September 1, 2015 a VOC (EPA Method 524.2) water sample was collected from the nearby drinking water well located at the Municipality of Anchorage's Oberg Ball Field Park located on Dallon Court. The drinking water sample was non-detect. In January 2015 eight additional soil borings are to be sampled to help delineate the extent of the soil contamination. On September 22-23, 2015 a vapor intrusion evaluation was conducted at 20808 Bill Stephens Drive. They collected one outdoor and three indoor air samples (plus one duplicate) to evaluated non-frozen ground conditions. All five samples were below ADEC target levels for indoor air at residential and commercial properties. A follow up sampling event during frozen ground conditions will also be required by March 31, 2016. In March 2016 indoor air sampling conducted during frozen ground conditions. The building is used for commercial on the first floor and residential on the second floor. The air samples were collected on the first floor only and they exceeded residential screening levels for benzene and chloroform but were below commercial screening levels. The consultant will discuss the sample results with the commercial and residential tenants. ADEC requested another indoor air sampling event during frozen ground conditions in the winter of 2016 or sooner if the tenants have concerns. In July 2016 ADEC approved of the June 2016 work plan for conducting a pilot test for the proposed Soil Vapor Extraction (SVE) treatment system. This pilot test will help collect the necessary site data to design a cost-effective SVE treatment system to remediate the site. In September 2018 the SVE system was installed and began operation. They continue to monitor and operate the SVE system and sample the groundwater.

Action Information

Action Date Action Description DEC Staff
9/30/2013 Spill Transferred from Prevention Preparedness and Response Program Spill transferred by PERP staff Shannon DeWandel. Spill no. 13239925802; spill date = 9/13/13; substance = petroleum; quantity = unknown; source = USTs #1 and #2 (2A & B). Mitzi Read
10/3/2013 Site Added to Database A new site has been added to the database Mitzi Read
10/3/2013 Leaking Underground Storage Tank Release Confirmed - Petroleum LUST site created in CSP database for source area UST #1 10,000-Gal Gas & UST #2 (2A & B) 12,000-Gal (6,000-Gas/6,000-Diesel), 79512. Contamination found during UST facility inspection at leaking sumps at the top of both tanks. The sumps were repaired and the fuel lines were replaced by the UST contactor. Mitzi Read
10/4/2013 Exposure Tracking Model Ranking Initial ranking with ETM completed for source area id: 79512 name: UST #1 10,000-Gal Gas & UST #2 (2A & B) 12,000-Gal (6,000-Gas/6,000-Diesel) Mitzi Read
11/4/2013 Potentially Responsible Party/State Interest Letter Notice of Hazardous Substance Liability Potential Responsible Party (PRP) letter sent to the current owner K & SC Corporation (Ms. Myong Kim). Bill Janes
11/26/2013 Underground Storage Tank Site Characterization or Assessment On September 17, 2013 about 5 cubic yards of contaminated soil was removed at the gasoline tank sump (tank 1) and stockpiled at the site on the north side of the building. One sample was collected from the stockpile had 1,510 mg/kg GRO, 4.53 mg/kg naphthalene, and 3.63 mg/kg benzene. One sample was collected from the excavation had 5,390 mg/kg GRO, and 26.6 mg/kg benzene. The nature and extent of the remaining contamination at this tank has not been defined. Robert Weimer
11/26/2013 Update or Other Action Also on September 17, 2013 an additional 5 cubic yards of contaminated soil was removed at the diesel/supreme gasoline tank sump (tank 2) and stockpiled at the site on the north side of the building. One sample was collected from the stockpile had 66.7 mg/kg DRO, 9.47 mg/kg GRO, and 0.0656 mg/kg benzene. One sample was collected from the excavation had 7.91 mg/kg GRO, non-detect (<21.8 mg/kg) DRO, non-detect (<54.6 mg/kg) RRO, non-detect (<0.0115 mg/kg) PAHs, and 0.078 mg/kg benzene. The nature and extent of the remaining contamination at this tank has not been defined. Robert Weimer
11/26/2013 Document, Report, or Work plan Review - other ADEC approves request to transport off property to thermally treat the two 5 cubic yard stockpiles at ASR. Robert Weimer
12/31/2013 Leaking Underground Storage Tank Cleanup Initiated - Petroleum Administrative action addition for grant reporting purposes. Evonne Reese
3/6/2014 Site Characterization Workplan Approved On February 19, 2014 a work plan was submitted for conducting a limited phase II environmental site assessment. The work plan proposes sampling 6 borings in the vicinity of a septic drainfield, trench drain, current septic tank, former USTs, and current USTs. Groundwater is not expected to be encountered (estimated to be at over 130 feet below ground surface). The work plan is approved with the following modifications: 1. Add total lead for all analytical samples. 2. Add VOCs (8260), PAH, and RCRA metals to the drain field and trench drain samples. Additional sampling will be needed in the future to fully define the nature and extent of the sump contamination discovered on 9/15/2013. Based on the results of the proposed assessment further assessment, monitoring, and/or corrective action may be required. Robert Weimer
4/28/2014 Document, Report, or Work plan Review - other On March 2014 four soil samples plus one duplicate were collected from four soil borings (one soil boring SB-4 had no analytical samples collected). Soil boring SB-1 was drilled to 20 feet below ground surface (bgs) near the on-property septic leach field had no detectable petroleum. Soil boring SB-2 was drilled to 39 feet bgs near the current tanks had a petroleum odors from 2.5 to the base of the boring at 39 feet bgs. In SB-2: 5,460 mg/kg GRO, 101 mg/kg DRO, non-detect (<21.3 mg/kg) RRO, 123 mg/kg benzene, and 3.81 mg/kg lead in the analytical soil sample collected at 12.5 bgs. In SB-2: 55.2 mg/kg GRO, non-detect (<21.3 mg/kg) DRO, non-detect (<21.3 mg/kg) RRO, 2.6 mg/kg benzene, and 8.54 mg/kg lead in the analytical soil sample collected at 39 bgs. Soil boring SB-3 was drilled to 15 feet bgs near the former tanks had a petroleum odors from the ground surface to the base of the boring at 15 feet bgs. In SB-3: 1,750 mg/kg GRO, 956 mg/kg DRO, non-detect (<20.8 mg/kg) RRO, 6.39 mg/kg benzene, and 4.61 mg/kg lead in the analytical soil sample collected at 15 bgs. The nature and extent of the remaining contamination at these areas has not been defined. According to the report, Cook Inlet Marketing Group (CIMG) directed their consultant (BGES) not to drill two (south the current USTs and north of the trench drain) of the proposed six soil borings that were specified in the DEC approved work plan. Robert Weimer
5/29/2014 Potentially Responsible Party/State Interest Letter Follow up Notice of Hazardous Substance Liability Potential Responsible Party (PRP) letter sent to the current owner K & SC Corporation (Ms. Myong Kim). In the letter ADEC also requests a work plan by August 1, 2014, including a schedule for conducting the work, for conducting a release investigation for these contaminated areas. This would include the sampling of any water wells at or near the property. This would also include the sampling of soil borings to determine the vertical and horizontal extent of the contamination in current and former underground storage tank areas. If contamination is found to extend to near the groundwater then long-term groundwater monitoring wells would need to be installed and sampled. ADEC also requests a corrective action work plan for remediating the contamination at this site be submitted by October 15, 2014, including a schedule for conducting the corrective action work. Robert Weimer
6/20/2014 Site Characterization Workplan Approved ADEC approves June 20, 2014 release investigation work plan. The plan proposes to sample 9 soil boring to help define the nature and extent of the contamination identified near soil borings SB-2 and SB-3. If groundwater is encountered at least one boring per area will be completed as a monitoring well, a water well search will be conducted in a quarter mile radius, and all water wells within 500 feet will be sampled. Work is scheduled to begin on June 23, 2014. Robert Weimer
7/8/2014 Update or Other Action Update from the property owners consultant (BGES) that they are having trouble drilling deeper than 112 feet, they would like to use a air rotary rig to drill deeper. We discussed that would be fine for installing a monitoring well, but any soil samples would be considered biased low due to the high pressure air used down the hole in the drilling. Robert Weimer
7/16/2014 Update or Other Action ADEC has no objection to request to use an special air rotary rig that has a split spoon sampler driven ahead to collect soil samples. They propose to collect volatile samples at 112 feet to compare the results of the auger sampling at that depth with those with an air rotary rig to help evaluate how much the volatile samples are being biased low due to the high pressure air used down the hole in the drilling. They are proposing to using an air rotary rig because of refusal encountered at 112 feet using an auger drill rig. Robert Weimer
7/29/2014 Update or Other Action Update from consultant that the special air rotary rig that has a split spoon sampler driven ahead to collect soil samples had low field readings at a location 5 feet horizontally away at the 112 feet depth. They plan to use the air rotary to evaluate field readings and analytical results at shallower soils to compare with the recent auger drilling in that area. Robert Weimer
8/1/2014 Update or Other Action Update from the property owners consultant (BGES) that one monitoring well has been completed and they found elevated field reading in the soils near the groundwater in that well. They propose to install two additional monitoring wells about 40 to 50 feet downgradient from that location to help define the extent of the soil and groundwater contamination in this area. Robert Weimer
8/5/2014 Document, Report, or Work plan Review - other Between July 29, 2014 and August 5, 2014 five soil borings (soil borings SB5, SB5A, SB5B, SB13, and SB14) were sampled to help define the extent of the soil contamination at this site. Up to 123.0 mg/kg benzene, 5,220 mg/kg GRO, 69.2 mg/kg DRO, and 22.1 mg/kg RRO in the samples collected. Robert Weimer
8/7/2014 Update or Other Action Update from the property owners consultant (BGES) that the 2nd and 3rd monitoring wells were completed on August 6, 2014. They plan to sample all three monitoring wells by August 8, 2014. The field readings at the soil/water interface in the 2nd and 3rd monitoring wells were lower than at the 1st monitoring well that is located closer to the release location at the current USTs. Groundwater was encountered at 139.5 feet below ground surface in the monitoring wells. The drinking water well survey of the area is scheduled to be conducted soon. Robert Weimer
8/8/2014 Update or Other Action Update from the property owners consultant (BGES) that high field readings and gasoline odors in the vapors in all three monitoring wells. While not measurable with the oil/water interface probe there appears to be a thin layer of gasoline product in all three monitoring wells, the groundwater samples will be run in the lab to compare concentrations. Additional monitoring wells are needed to define the extent of the groundwater contamination. Robert Weimer
8/12/2014 Document, Report, or Work plan Review - other August 11-12, 2014 groundwater sampling event. The three site monitoring wells were purged prior to sampling within the top foot of the water column as required. Up to 18.8 ug/l benzene, 0.145 mg/l GRO, non-detect lead, and non-detect PAHs in the groundwater samples collected. Groundwater flow direction was to the west by southwest with a depth to groundwater of 139.46 to 140.03 below ground surface. Robert Weimer
8/21/2014 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 79512 UST #1 10,000-Gal Gas & UST #2 (2A & B) 12,000-Gal (6,000-Supreme Gas/6,000-Diesel). Robert Weimer
9/8/2014 Update or Other Action Call from nearby property owner who has a drinking water well located about 650 feet from the Peters Creek Chevron property. We discussed that Peters Creek Chevron hopes to have their consultant complete a drinking water well search for at least the first 1/4 mile radius, and sample drinking water wells in the area by September 12, 2014. Robert Weimer
9/8/2014 Update or Other Action ADEC contacted Peters Creek Chevron's consultant (BGES) to get an update on the status of the required drinking water well search and sampling of drinking water wells in the area. BGES said that they had been informed by Peters Creek Chevron's representative that further work was currently on hold. We discussed that it is critical that a drinking water well search for at least the first 1/4 mile radius, and sample drinking water wells in the area be completed as soon as possible and by September 12, 2014. BGES said they would follow up with the Peters Creek Chevron's representative. Later ADEC was contacted by Peters Creek Chevron's representative that after they contact the insurance company tomorrow morning about funding the site work, they would provide an update to ADEC about conducting a drinking water well search for at least the first 1/4 mile radius, and sample drinking water wells in the area be completed as soon as possible and by September 12, 2014. Robert Weimer
9/10/2014 Update or Other Action ADEC received an email from KSC's attorney that KSC in not in the financial position to fund additional environmental work (including the drinking water well search and sampling of drinking water wells in the area) at the site until the insurance company begins to pay for the work. KSC's attorney stated that it appears that KSC may need to initiate litigation to get the insurance company to pay. Robert Weimer
9/10/2014 Update or Other Action ADEC called the nearby property owner who had called on September 8, 2014 regarding her drinking water well located about 650 feet from the Peters Creek Chevron property. I informed her about what KSC’s attorney had said. I recommending to that she have her drinking water well sampled for VOC’s (524.2) and GRO (AK 101) since it did not appear, based on the email, that KSC would be doing it anytime soon. She said that she intended to have her well sampled soon and would submit the results to me once she gets them. She stated that she had heard that the static water level in her water well was about 155 feet below ground surface, which would indicate that it is drawing water from same aquifer that the Peters Creek Chevron property found groundwater contamination at 139.5 feet below ground surface. Robert Weimer
9/16/2014 Update or Other Action ADEC letter to the RP requesting a drinking water well search and drinking water well sampling. ADEC again requests that a 1/4 mile or greater drinking water well search be completed and submitted to ADEC by no later than September 22, 2014, along with a work plan for the sampling and laboratory analysis of the drinking water wells potentially at risk in the area. The work plan is to include a schedule for conducting the drinking water well sampling by no later than September 29, 2014. The letter also noted that is they are unwilling or unable to conduct the requested work in the timeframe requested, ADEC may hire one of their term contractors to do the work and recover the costs from the RP. Robert Weimer
9/19/2014 Update or Other Action ADEC received an email from KSC's attorney that KSC in not in the financial position to conduct the requested drinking water well search and sampling. Robert Weimer
10/6/2014 Update or Other Action ADEC received the results of the drinking water well sampling conducted on September 19, 2014 at the nearby property well located about 650 feet from the Peters Creek Chevron property. The owner of that property hired their own consultant (ArcTerra Consulting) to conduct the sampling since the Peters Creek Chevron property owner was unwilling/unable to conduct the work. The drinking water well was sampled for VOC’s (524.2) and GRO (AK 101), all were non-detect. The information submitted documented that the static water level was measured on August 28, 2012 was 155 feet below ground surface, which would indicate that it is drawing water from same aquifer that the Peters Creek Chevron property found groundwater contamination at 139.5 feet below ground surface. Robert Weimer
10/7/2014 Update or Other Action ADEC received an email from KSC's attorney that the insurance company ASIC has authorized the consultant BGES to conduct the requested drinking water well search and sampling. BGES called ADEC and said they would be completing the work soon. Robert Weimer
10/23/2014 Update or Other Action ADEC received notification from KSC's consultant BGES that they have been authorized to complete the reports for the work previously done, collect water samples from the site monitoring wells, and continue release investigation work. Robert Weimer
11/12/2014 Document, Report, or Work plan Review - other ADEC review of BGES October 27, 2014 Drinking Water Well Survey report. The report documented the results of a 1/4 mile drinking water well survey. The report identified 77 active water wells with 1/4 mile and recommended water sampling at 10 of them for BTEX by EPA Method 524.2. The report identified that there may be some additional drinking water wells in the area on lots not currently in well databases and they plan to conduct additional field surveys and/or telephone surveys of those lots. Based on the survey results they may recommend additional water wells to be sampled. ADEC has no objection to them conducting the drinking water well sampling recommended in the report. Robert Weimer
11/14/2014 Document, Report, or Work plan Review - other November 10-12, 2014 groundwater sampling event. The three site monitoring wells were purged prior to sampling within the top foot of the water column as required. All samples were non-detect for benzene and GRO in the groundwater samples collected. Groundwater flow direction was to the west by southwest with a depth to groundwater of 140.72 to 141.32 below ground surface. Robert Weimer
12/17/2014 Document, Report, or Work plan Review - other December 17, 2014 groundwater sampling event. The new site monitoring well (MW-4) was purged prior to sampling within the top foot of the water column as required. All samples were non-detect for BTEX, GRO, DRO, and RRO in the groundwater sample collected. Depth to groundwater was 140.73 below ground surface. Robert Weimer
1/6/2015 Update or Other Action Based on existing site sample data and site conditions ADEC concurs with the recommendation of the RP's consultant that sampling in the Glenn Highway ROW is needed in order to define the extent of the contamination at this site. The proposed 8 locations are approved for ADEC Contaminated Sites Program purposes. They expect to begin the work by January 16, 2015. Based on the results additional sampling may be required to define the nature and extent of the contamination for this site. Robert Weimer
1/6/2015 Document, Report, or Work plan Review - other In October 2014 three borings were sampled (SB15, SB16, SB17) and SB17 was completed as a monitoring well. Up to 14.3 mg/kg benzene and 379 mg/kg GRO in the soil samples collected. Robert Weimer
1/29/2015 Document, Report, or Work plan Review - other ADEC approves request not to advance proposed soil boring north of the propane tank. ADEC also approves request for a reduction in the sample frequency for the two borings along the southbound lane of the Glenn Highway. Robert Weimer
2/11/2015 Document, Report, or Work plan Review - other Between November 26, 2014 and February 11, 2015 eight soil borings (soil borings SB18 - SB25) were sampled to help define the extent of the soil contamination at this site. All samples collected were non-detect BTEX and GRO. Robert Weimer
2/26/2015 Update or Other Action ADEC requests that the 4 monitoring wells at the Peters Creek Chevron site be sampled for BTEX and GRO by no later than March 31, 2015, and quarterly thereafter. ADEC is also requesting a report of the results of this monitoring event and all previous groundwater monitoring events be submitted by May 15, 2015. ADEC requests that the results of future monitoring events (after the March 2015 event) be submitted within 60 days of when the sampling is conducted. Robert Weimer
3/20/2015 Document, Report, or Work plan Review - other March 18-20, 2015 groundwater sampling event. The four site monitoring wells were purged prior to sampling within the top foot of the water column as required. All samples were non-detect for BTEX and GRO in the groundwater samples collected. Groundwater flow direction was to the west by southwest with a depth to groundwater of 142.05 to 143.00 below ground surface. Robert Weimer
4/17/2015 Document, Report, or Work plan Review - other Between December 30, 2014 and February 19, 2015 VOC (EPA Method 524.2) water samples were collected from 5 nearby drinking water wells located at 20727 Oberg Road, 22733 Friendship Lane, 20707 Oberg Road, 20912 Four Wheel Drive, and 20640 Chapel Road. All of the drinking water samples were non-detect. Robert Weimer
6/26/2015 Update or Other Action ADEC confirmed in discussions with the consultant that active remediation (corrective action) will be required for the remaining contamination at this site. Robert Weimer
9/9/2015 Document, Report, or Work plan Review - other ADEC approved the August 26, 2015 work plan for conducting an evaluation of vapor intrusion at 20808 Bill Stephens Drive. The work plan proposes to collect one outdoor and three indoor air samples (plus one duplicate) in the fall of 2015 for non-frozen ground conditions. A follow up sampling event during frozen ground conditions will also be required by March 31, 2016. Robert Weimer
10/9/2015 Offsite Soil or Groundwater Disposal Approved ADEC approves 440 gallons of monitoring well purge/development water for treatment and disposal at NRC Alaska. ADEC approves thermal treatment at ASR of 31.5 tons of contaminated drill cuttings. Robert Weimer
10/30/2015 Offsite Soil or Groundwater Disposal Approved ADEC approves disposal at Anchorage Regional Landfill of an additional 24 tons of contaminated drill cuttings. Robert Weimer
12/10/2015 Document, Report, or Work plan Review - other On September 22-23, 2015 a vapor intrusion evaluation was conducted at 20808 Bill Stephens Drive. They collected one outdoor and three indoor air samples (plus one duplicate) to evaluated non-frozen ground conditions. All five samples were below ADEC target levels for indoor air at residential and commercial properties. A follow up sampling event during frozen ground conditions will also be required by March 31, 2016. Robert Weimer
12/11/2015 Document, Report, or Work plan Review - other The Alaska Department of Environmental Conservation (ADEC) has reviewed the BGES “Indoor Air Investigation and Feasibility Study” report dated December 2015 (report). This report included a detailed assessment of different remedial alternatives (corrective action) for the contamination identified at this site, and recommended ex-situ thermal remediation combined with soil vapor extraction (SVE) as the selected remedy for this site. ADEC concurs with that recommendation. ADEC requests that you submit by March 1, 2016, for ADEC review and approval, a work plan for conducting a pilot test for the SVE. This pilot test will help collect the necessary site data to design a cost-effective SVE treatment system to remediate your site. The report discussed the possibly collecting additional site data and establishing site specific method 3 or 4 cleanup levels prior to installing a remediation system at this site. This request is not approved for two reasons: 1. We don’t want to delay the required active remediation (corrective action) of the contamination at this site, and 2. Given the porous soil type, type of contamination (BTEX and GRO), the migration of the contamination to groundwater, the active drinking water wells in the area, and site contamination extending off-property it is not likely that any higher site specific alternative cleanup levels would be approved based on a method 3 or 4 evaluation. The ADEC would like to see the funds available for this site spent on the remediation of the site, instead spending funds on the collection of additional site data required for and preparing a method 3 or 4 evaluation. Robert Weimer
12/15/2015 Document, Report, or Work plan Review - other On September 1, 2015 a VOC (EPA Method 524.2) water sample was collected from the nearby drinking water well located at the Municipality of Anchorage's Oberg Ball Field Park located on Dallon Court. The drinking water sample was non-detect. Robert Weimer
2/29/2016 Update or Other Action Peters Creek Chevron's consultant requested an extension for the submittal by March 1, 2016, for ADEC review and approval, a work plan for conducting a pilot test for the SVE. This pilot test will help collect the necessary site data to design a cost-effective SVE treatment system to remediate the site. They have not been authorized by the insurance company to prepare the requested work plan. An extension to March 31, 2016 is approved. Robert Weimer
3/7/2016 Document, Report, or Work plan Review - other ADEC approves request to conduct indoor air sampling in accordance with the previously approved work plan. The frozen ground condition sampling is planned to be conducted on March 8-9, 2016. Robert Weimer
4/1/2016 Update or Other Action On March 31, 2016 Peters Creek Chevron's consultant requested an extension for the submittal for ADEC review and approval of a work plan for conducting a pilot test for the SVE. This pilot test will help collect the necessary site data to design a cost-effective SVE treatment system to remediate the site. An extension to April 30, 2016 is approved. Robert Weimer
4/1/2016 Meeting or Teleconference Held Discussion with RPs consultant about the results of the recent indoor air sampling conducted during frozen ground conditions. The building is used for commercial on the first floor and residential on the second floor. The air samples were collected on the first floor. The indoor air samples had 3.3 to 3.7 ug/m3 benzene (3.1 ug/m3 residential screening level), and 1.8 ug/m3 chloroform (1.1 ug/m3 residential screening level). The outdoor sample from behind the building had 1.8 ug/m3 benzene. The samples were collected during operation of the gas station which may have influenced the benzene results. They will take another frozen ground sampling next winter. They will discuss the results with the property owner/residents and if there are concerns they may conduct another indoor air sampling event soon. They will also recommend that the weather striping on the doors be improved to reduce the amount of air entering the building from the fueling operations. Future outdoor air sampling to be conducted on the side of the building facing the fueling operations. Robert Weimer
4/29/2016 Update or Other Action On April 29, 2016 Peters Creek Chevron's consultant requested an extension for the submittal for ADEC review and approval of a work plan for conducting a pilot test for the SVE. This pilot test will help collect the necessary site data to design a cost-effective SVE treatment system to remediate the site. An extension to June 1, 2016 is approved. Robert Weimer
5/31/2016 Update or Other Action On May 31, 2016 Peters Creek Chevron's consultant requested an extension for the submittal for ADEC review and approval of a work plan for conducting a pilot test for the SVE. This pilot test will help collect the necessary site data to design a cost-effective SVE treatment system to remediate the site. An extension to June 30, 2016 is approved. Robert Weimer
7/7/2016 Site Visit Site visit to observe groundwater monitoring and to evaluate current site conditions for planned site work. Robert Weimer
7/19/2016 Document, Report, or Work plan Review - other ADEC approval of the June 2016 work plan for conducting a pilot test for the proposed Soil Vapor Extraction (SVE) treatment system. This pilot test will help collect the necessary site data to design a cost-effective SVE treatment system to remediate the site. Robert Weimer
1/6/2017 Update or Other Action Update from consultant (BGES) that they will begin the pilot testing of the extraction points on January 10, 2017. Robert Weimer
3/10/2017 Meeting or Teleconference Held Meeting with owners representative and their consultants to discuss the results of the VES pilot study and future site work. They are to provide the groundwater monitoring report by the end of the month, conduct the indoor air sampling within a month, and submit the work plan for the installation of the VES system by end of April. Robert Weimer
4/4/2017 Update or Other Action Call from consultant that they are conducting the indoor air sampling today. They did not get enough tight canisters from the lab so it is ok to not do a duplicate air sampler this event. Robert Weimer
5/25/2017 Document, Report, or Work plan Review - other August 19-20, 2015 groundwater sampling event. The four site monitoring wells were purged prior to sampling within the top foot of the water column as required. Monitoring well MW-1 was the only monitoring well with detectable contamination (3.13 ug/l benzene) this monitoring event. All groundwater samples were non-detect for GRO. The concentrations increased in 1 of the 4 monitoring wells sampled. Groundwater flow direction was to the west by southwest with a depth to groundwater of 144.13 to 145.03 below ground surface. Robert Weimer
5/25/2017 Document, Report, or Work plan Review - other December 29-31, 2015 groundwater sampling event. The four site monitoring wells were purged prior to sampling within the top foot of the water column as required. All groundwater samples were non-detect for GRO and BTEX. The concentrations increased in 0 of the 4 monitoring wells sampled. Groundwater flow direction was to the west by southwest with a depth to groundwater of 142.35 to 143.20 below ground surface. Robert Weimer
5/26/2017 Document, Report, or Work plan Review - other March 10-11, 2016 groundwater sampling event. The four site monitoring wells were purged prior to sampling within the top foot of the water column as required. All groundwater samples were non-detect for GRO and BTEX. The concentrations increased in 0 of the 4 monitoring wells sampled. Groundwater flow direction was to the west by southwest with a depth to groundwater of 145.13 to 145.97 below ground surface. Robert Weimer
5/26/2017 Document, Report, or Work plan Review - other July 6-7, 2016 groundwater sampling event. The four site monitoring wells were purged prior to sampling within the top foot of the water column as required. Monitoring well MW-1 was the only monitoring well with detectable contamination (30 ug/l benzene and 2.13 ug/l toluene) this monitoring event. All groundwater samples were non-detect for GRO. The concentrations increased in 1 of the 4 monitoring wells sampled. Groundwater flow direction was to the west by southwest with a depth to groundwater of 145.88 to 146.83 below ground surface. Robert Weimer
9/8/2017 Document, Report, or Work plan Review - other March 10, 2016 indoor air sampling conducted during frozen ground conditions. The building is used for commercial on the first floor and residential on the second floor. The air samples were collected on the first floor. The indoor air samples had 3.2 to 3.7 ug/m3 benzene (3.6 ug/m3 residential screening level), and 1.3 ug/m3 chloroform (1.2 ug/m3 residential screening level). The other detected compounds were below residential screening levels. The outdoor sample from behind the building had 1.8 ug/m3 benzene. Robert Weimer
9/8/2017 Document, Report, or Work plan Review - other May 5, 2016 indoor air sampling conducted during non-frozen ground conditions. The building is used for commercial on the first floor and residential on the second floor. The weather stripping on the outside door was improved since the March 2016 indoor air sampling event. Three air samples were collected on the first floor and two samples were collected from two of the residential apartments on the second floor. The indoor air samples had 0.65 to 2.3 ug/m3 benzene (3.6 ug/m3 residential screening level), and non-detect to 2.2 ug/m3 chloroform (1.2 ug/m3 residential screening level). The other detected compounds were below residential screening levels. The residential apartment samples were below screening levels for all compounds. The outdoor air samples were collected from in front of the building and behind the building on the 2nd floor balcony had up to 2.0 ug/m3 benzene, non-detect chloroform, and 7.5 ug/m3 1,2-Dichloropropane (2.8 ug/m3 residential screening level). The highest concentrations in outdoor air was from the sample collected in front of the building. Robert Weimer
9/22/2017 Document, Report, or Work plan Review - other April 5, 2017 indoor air sampling conducted during frozen ground conditions. The building is used for commercial on the first floor and residential on the second floor. Three air samples were collected on the first floor and two samples were collected from two of the residential apartments on the second floor. The indoor air samples collected on the first floor had up to 5.3 ug/m3 benzene (16 ug/m3 commercial screening level), 2.8 ug/m3 TCE (8.4 ug/m3 commercial screening level), and 3.0 ug/m3 chloroform (5.3 ug/m3 commercial screening level). The indoor air samples on the second floor had non-detect to 2.0 ug/m3 chloroform (1.2 ug/m3 residential screening level). The other detected compounds were below residential screening levels. The outdoor air samples were collected from in front of the building and behind the building both on the 2nd floor balcony had up to 4.4 ug/m3 benzene, and non-detect chloroform. The highest concentrations in outdoor air was from the sample collected in front of the building, nearest to the fueling operations. Robert Weimer
10/10/2017 Document, Report, or Work plan Review - other DEC approves October 2017 Revised Soil Vapor Extraction System Installation Work Plan. The work plan is for the installation, operation, and monitoring of the soil vapor extraction (SVE) system, the semi-annual groundwater monitoring, indoor air sampling, and sampling and reuse of soil generated during the SVE installation. Robert Weimer
11/22/2017 Update or Other Action DEC receives notification that due to frozen ground conditions the installation of the Soil Vapor Extraction System has been delayed until the ground thaws out in 2018. They will continue semi-annual groundwater monitoring and indoor air sampling as per the approved work plan. Robert Weimer
5/23/2018 Offsite Soil or Groundwater Disposal Approved DEC approves request to transport 250-300 cubic yards of contaminated soil to ASR. The soil is to be generated during the installation of the vapor extraction system. Robert Weimer
7/20/2018 Update or Other Action Based on the information presented DEC has no objection to reuse of the 45 cubic yards of “apparently clean” stockpile soils on 20808 Bill Stephens Drive property a minimum of 100’ away from any drinking water wells. All of the stockpile samples meet Method 2 migration to groundwater cleanup levels, they had up to 23.3 mg/kg DRO, and non-detect for GRO, VOCs, and PAHs. This stockpile was also generated during the installation of the soil vapor extraction remediation system. Robert Weimer
3/15/2019 Update or Other Action DEC receives notification that the consultant plans to conduct indoor air sampling on March 18-19, 2019. They also plan to conduct groundwater monitoring and operate the SVE system in 2018 and 2019. A report of the results is expected in August 2019. Robert Weimer
3/2/2020 Document, Report, or Work plan Review - other February 14, 2018 indoor air sampling conducted during frozen ground conditions. The building is used for commercial on the first floor and residential on the second floor. Two outdoor samples, two indoor samples on the second floor, and three indoor samples plus one duplicate sample on the first floor of the building. All samples were below residential target levels. Up to 3.2 ug/m3 benzene in the samples collected. The residential target level is 3.6 ug/m3. Robert Weimer
3/2/2020 Document, Report, or Work plan Review - other October 16, 2017 groundwater sampling event. Two (MW-2 and MW-3) of the four site monitoring wells were purged prior to sampling within the top foot of the water column as required. Monitoring well MW-1 and MW-4 did not have sufficient water for sampling due to the low water levels. The two monitoring wells sampled were non-detect for GRO, VOCs, and PAHs. Groundwater flow direction was to the northwest with a depth to groundwater of 147.18 to 148.90 below ground surface. Monitoring well MW-1 exceeded cleanup levels with 30.0 ug/l benzene the last time it was sampled in July 2016. Robert Weimer
3/20/2020 Document, Report, or Work plan Review - other DEC received notification that the SVE system is currently down due to electrical issues. DEC approved request to suspend operations of the SVE system until June 15, 2020 or the end of the coronavirus pandemic, whichever comes first. Robert Weimer
8/17/2020 Update or Other Action DEC received notification that groundwater sampling is planned for the 4 existing monitoring wells on August 19th and 20th. Janice Wiegers
11/17/2020 Update or Other Action Reviewed SVE System report and indoor air sampling reports. Approved consultant request to disable SVE system for the winter. System is not necessary to mitigate vapor intrusion in building and frozen ground limits system efficacy during winter. Michael Hooper
3/15/2022 Document, Report, or Work plan Review - other Approved report detailing SVE system operations and groundwater monitoring. SVE system seems to have reached diminishing returns. groundwater concentrations were non-detect in last sampling event (Fall 2020). Recommended an additional round of GWM and decommissioning SVE system. Michael Hooper
5/26/2022 Site Characterization Report Approved Reviewed GWM Report, all contaminants of concern were below the cleanup levels. Michael Hooper
6/29/2023 Cleanup Complete Determination Issued ADEC has approved closure with institutional controls pending finalization of the environmental covenant on the property. The SVE system and wells were decommissioned in June 2023. Michael Hooper
6/29/2023 Institutional Control Record Established Institutional Controls established and entered into the database. Michael Hooper
3/7/2024 Institutional Control Update Received signed and recorded copy of Environmental Covenant back from recorder's office and sent out final closure letter. Michael Hooper

Contaminant Information

Name Level Description Media Comments
GRO > Human Health/Ingestion/Inhalation Soil GRO contamination exceeded HH CULs prior to SVE system operation.
BTEX > Human Health/Ingestion/Inhalation Soil BTEX contamination exceeded HH CULs prior to SVE system operation.

Control Type

Type Details
Environmental Covenant

Requirements

Description Details
Groundwater Use Restrictions 1. No groundwater wells shall be installed on the contaminated area of the Property without prior DEC approval.
Groundwater Use Restrictions 2. Contaminated groundwater underlying the Property may not be pumped, drained, or dewatered; or used for irrigation, dust control, or any other purpose without prior DEC approval. If that use is approved under this Covenant, that use is still subject to all applicable treatment, monitoring, disposal, and permitting requirements.
New Construction Restrictions 3. If the use of a building on the Site changes, or if buildings are constructed within 30 feet of tanks #1 and #2, DEC must be notified and may require that Grantor complete an evaluation of vapor intrusion and mitigation of any vapor intrusion risks.
Excavation / Soil Movement Restrictions 4. Excavation, drilling, and other intrusive activities below a depth of 2 feet are prohibited within the Site, without prior review and approval from DEC.
When Contaminated Soil is Accessible, Remediation Should Occur 5. In the event that contaminated soil on the Property becomes accessible in the future, the Grantor shall notify DEC, characterize the contamination, and, if determined necessary by DEC, cleanup the soil pursuant to DEC’s Site Cleanup Rules.
Subdivision Restriction 6. DEC must be notified in advance of any subdivision or replat of the Property. This Covenant must be included as part of future Property transactions and attached to subsequent associated parcels, as determined applicable by DEC.
Advance approval required to transport soil or groundwater off-site. Standard Condition 1. DEC approval is required prior to moving soil or groundwater where contamination remains above applicable cleanup levels. If DEC approval for movement is granted, any moved soil or groundwater must still be characterized and managed following regulations applicable at that time.
Movement or use of contaminated material (including on site) in a manner that results in a violation of the water quality standards is prohibited (18 AAC 70) Standard Condition 2. Movement or use of contaminated material in a manner that results in a violation of 18 AAC 70 Water Quality Standards is prohibited.
Groundwater Use Restrictions Standard Condition 3. Groundwater throughout Alaska is protected for use as a water supply for drinking, culinary and food processing, agriculture including irrigation and stock watering, aquaculture, and industrial use. Contaminated site cleanup complete determinations are based on groundwater being considered a potential drinking water source. In the event that groundwater from this Site is to be used for other purposes in the future, such as aquaculture, additional characterization and treatment may be required to ensure the water is suitable for its intended use.
Hazard ID Site Name File Number
23948 Chevron - Peters Creek 2106.26.012

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