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Site Report: Residence - 3102 West 29th Avenue HHOT

Site Name: Residence - 3102 West 29th Avenue HHOT
Address: 3102 West 29th Avenue, Anchorage, AK 99517
File Number: 2100.38.473
Hazard ID: 4282
Status: Active
Staff: Bill O'Connell, 9072693057 bill.oconnell@alaska.gov
Latitude: 61.194253
Longitude: -149.941505
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

During the removal of a home heating oil tank on July 24, 2006 contamination was found in the soil and groundwater. In 2006 around 101.8 tons of contaminated soil was excavated and thermally treated at an off-site treatment facility. Groundwater was encountered at 10 feet below ground surface during the excavation, and has ranged from 8 to 12 feet below ground surface during the groundwater monitoring. Up to 3,880 mg/kg DRO remains at 11 feet below ground surface. Up to 2,410 mg/kg DRO remains at 13.5 feet below ground surface. Three monitoring wells were installed in 2006 to help define the extent of the groundwater contamination at this site. Currently DRO contamination in the soil and groundwater remain at this residential property.

Action Information

Action Date Action Description DEC Staff
8/17/2006 Site Characterization Report Approved Initial excavtion results show up to 11,500 mg/kg DRO remain in the soil. Groundwater was encounted at 10 feet below ground surface and had up to 1840 ug/l benzene, 2.36 mg/l GRO, and 79.4 mg/l DRO. ADEC recommends that additional soil and groundwater be removed prior to backfilling the excavation. Robert Weimer
8/24/2006 Spill Transferred from Prevention Preparedness and Response Program Site transfered from Eric Henry, PERP project manager. Spill No. 06239920502; contamination discovered on 7/24/06; spill amount unknown. Robert Weimer
8/31/2006 Site Added to Database Site added to the database. Mitzi Read
9/19/2006 Cleanup Plan Approved On 8/28/06 and additional 12 cubic yards of contaminted soil was excavated and transported for thermal treatment at ASR. Three confirmation soil samples were collected from the excavation. They also pumped out 2 drums of contaminated water out of the excavation. Groundwater was encountered at 10 feet below ground surface. Robert Weimer
12/5/2006 Update or Other Action Review and conditionally approve plan for installing monitoring wells to define the level and extent of the remaining groundwater contamination. ADEC requests three monitoring wells be installed to determine the groundwater low direction at the site. ADEC also requests that the monitoring well placed closest to the excavation be sampled initially for BTEX, GRO, and DRO. Robert Weimer
12/5/2006 Site Characterization Report Approved On August 28, 2006 12 cubic yards of additional contaminated soil and 100 gallons of contaminated water from the excavation was removed. Up to 3,880 mg/kg DRO remains at 11 feet below ground surface. Up to 2,410 mg/kg DRO remains at 13.5 feet below ground surface. Groundwater was encountered at 10 feet below ground surface. At total of 101.8 tons of contamianted soil was thermally treated at ASR. Robert Weimer
4/18/2007 Update or Other Action Review Monitoring well installation and site assessment report. One monitoring well was installed on 12/12/06. The groundwater sample had 11.9 mg/l DRO, 0.0832 mg/l GRO, and non-detect for BTEX. Depth to groundwater was 8.8 feet below ground surface. The report recommends the installation of two additional monitoring wells to help determine groundwater flow direction and the extent of the groundwater contamination. The report also recommends conducting a drinking water well search in the area. Robert Weimer
4/18/2007 Site Characterization Workplan Approved ADEC approves proposal to install two additional monitoring wells (hand driven well points) and to sample all three monitoring wells for BTEX, GRO, and DRO. Robert Weimer
6/16/2008 Exposure Tracking Model Ranking Initial ranking with ETM completed. Robert Weimer
9/4/2008 Update or Other Action Review Monitoring well installation and sampling report. Two additional monitoring wells (MW-2 and MW-3) were installed on 5/23/07. A slight sheen was found in the purge water in monitoring well MW-2. The groundwater samples had up to 4.5 mg/l DRO, 0.061 mg/l GRO, and non-detect for BTEX. Depth to groundwater was around 8.8 feet below ground surface. The groundwater flow direction was flat but towards the northwest (there is not downgradient monitoring well in that direction). The report documented a drinking water well search in the area and no drinking water wells were found in the search area. Water results are considered biased low because the water samples were not kept at a low enough temperature. Robert Weimer
9/30/2008 Update or Other Action Talked with RP's consultant. ADEC is requesting that all 3 monitoring wells are sampled for BTEX, GRO, and DRO, along with groundwater elevations. If they want to propose natural attenuation then natural attenuation parameters also need to be collected. Robert Weimer
3/5/2009 Document, Report, or Work plan Review - other Reviewed groundwater sampling report. The three monitoring wells were sampled on October 20, 2008. A slight sheen was found in the purge water in monitoring well MW-2. The groundwater samples had up to 5.92 mg/l DRO, and non detect (<0.5 ug/l) benzene. GRO was not not collected as requested. Contamination levels are increasing. Depth to groundwater was around 8 feet below ground surface. The groundwater flow direction was flat but towards the east. Natural attenuation parameters were collected but there is insufficent data to estimate a reliable attenuation rate for this site. Robert Weimer
3/5/2009 Conceptual Site Model Submitted Conceptual Site Model identified subsurface soil soil ingestion, migration to groundwater, and ingestion of groundwater. Robert Weimer
4/24/2009 Update or Other Action ADEC letter requesting at least 3 more groundwater monitoring events for all 3 monitoring wells for BTEX, GRO, and DRO, with the results of the 2009 groundwater monitoring submitted by December 1, 2009. Based on the results, groundwater monitoring may be reduced and/or cleanup complete status with institutional controls may be approved for this site. Robert Weimer
5/17/2010 Document, Report, or Work plan Review - other Reviewed groundwater sampling report. The three monitoring wells were sampled on October 9, 2009. A slight sheen was found in the purge water in monitoring well MW-2. The groundwater samples had up to 3.13 mg/l DRO, non detect (<0.05 mg/l) GRO, and non detect (<0.5 ug/l) benzene. Contamination concentrations increased in 2 of the 3 monitoring wells sampled. Dissolved DRO was detectable in monitoring wells MW-2 and MW-3 for the first time. Depth to groundwater was around 8 feet below ground surface. The groundwater flow direction was flat but towards the east. Natural attenuation parameters were collected but there is insufficent data to estimate a reliable attenuation rate for this site. At least 2 more groundwater monitoring are needed to evaluate the site a reduction in groundwater monitoring or for site closure. Monitoring well MW1 has a fuel odor. Robert Weimer
9/27/2010 Site Characterization Workplan Approved Approved groundwater monitoring plan for the fall 2010 groundwater monitoring event. Monitoring well MW1 is to be sampled for BTEX & GRO with a Hydrasleeve, and DRO with peristaltic pump. Monitoring wells MW2 & MW3 are to be sampled for DRO. Robert Weimer
10/12/2011 Site Characterization Report Approved Reviewed groundwater sampling report. The three monitoring wells were sampled on October 7, 2010. A slight sheen was found in the purge water in monitoring well MW-2. The groundwater samples had up to 4.3 mg/l DRO, non detect (<0.05 mg/l) GRO, and non detect (<0.5 ug/l) benzene. Contamination concentrations increased in 1 of the 3 monitoring wells sampled. Depth to groundwater was between 10.85 to 11.06 feet below ground surface. The groundwater flow direction was flat but towards the east. Monitoring well MW1 has a sheen and fuel odor. Robert Weimer
12/6/2012 Site Characterization Report Approved Reviewed groundwater sampling report. The three monitoring wells were sampled on October 17, 2011. A slight sheen was found in the purge water in monitoring well MW-2. The groundwater samples had up to 2.64 mg/l DRO, 1.1 mg/l GRO, and non detect (<0.5 ug/l) benzene. Contamination concentrations increased in 2 of the 3 monitoring wells sampled. Depth to groundwater was between 11.66 to 12.54 feet below ground surface. The groundwater flow direction was flat but towards the east. Monitoring well MW1 continues to have a sheen. Annual groundwater monitoring is to continue. Robert Weimer
12/6/2012 Meeting or Teleconference Held Discuss site groundwater monitoring with the RP's consultant (EMI). DEC requests continued annual groundwater monitoring, but can reduce, until further notice, sampling to just monitoring well MW1 and MW3 for DRO. Robert Weimer
10/2/2013 Document, Report, or Work plan Review - other Reviewed groundwater sampling report. Two of the three monitoring wells (MW1 & MW3) were sampled on December 28, 2012. A slight sheen was found in the purge water in monitoring well MW1. The groundwater samples had up to 70.4 mg/l DRO, this was the highest concentration of DRO ever detected in the groundwater at this site. Contamination concentrations increased in 1 of the 2 monitoring wells sampled. Depth to groundwater was between 10.60 to 11.29 feet below ground surface. The groundwater flow direction was flat but towards the east. Monitoring well MW1 continues to have a sheen. Annual groundwater monitoring is to continue. Monitoring wells were purged prior to sampling and sampled using a bailer. Robert Weimer
10/21/2013 Document, Report, or Work plan Review - other Reviewed groundwater sampling report. Two of the three monitoring wells (MW1 & MW2) were sampled on August 19, 2013. A slight sheen was found in the purge water in monitoring wells MW1 & MW2. The groundwater samples had 10.8 mg/l DRO (MW1) and 5.09 mg/l DRO (MW2). The 5.09 mg/l DRO in the monitoring well MW2 (located about 25 feet away from the former tank) was the highest concentration of DRO ever detected in that monitoring well, all previous groundwater samples in that monitoring well had been non-detect. Contamination concentrations increased in 1 of the 2 monitoring wells sampled. Depth to groundwater was between 9.90 to 10.79 feet below ground surface. The historically the groundwater flow direction is flat but towards the east. Monitoring well MW2 was purged prior to sampling and sampled using a bailer. Monitoring well MW1 was sampled using a Hydrasleeve and was not purged pior to sampling. Need quartery groundwater monitoring in all 3 monitoring wells. Robert Weimer
10/21/2013 Update or Other Action Talked with RPs consultant. Need quartery groundwater monitoring in all 3 monitoring wells. The next monitoring event is to occur in November/December 2013. Robert Weimer
11/25/2015 Update or Other Action Contacted RPs consultant about possible report on Nov/Dec 2013 Groundwater sampling report. Lisa Griswold
1/6/2016 Update or Other Action ADEC was notified by NeighborWorks Alaska that a meeting concerning the future work on the site is to occur with owners and responsible parties the week of January 4, 2016. Results of meeting are pending. Lisa Griswold
1/13/2016 Update or Other Action ADEC was notified by Neighborworks Alaska that the consultant will be submitting information pertaining to annual sampling for 2016. Lisa Griswold
2/16/2016 Document, Report, or Work plan Review - other Groundwater Monitoring Work Plan received from consultant on January 27. Clarification on items was requested on February 2, 2016, and a revised groundwater monitoring work plan was received February 11, 2016. The revised groundwater monitoring work plan details plans to take samples from the three groundwater monitoring wells onsite, as well as install a temporary well on the adjacent property in order to determine if contamination has crossed the property line. The work plan is conditionally approved upon submission of lab data results, field notes, and a CSM with the monitoring report, as well as a copy of the consultant's water discharge permit if it is utilized for disposal of investigative derived waste. Lisa Griswold
9/21/2016 Document, Report, or Work plan Review - other Groundwater Monitoring Report for Residence - 3102 West 29th Avenue HHOT was reviewed on this date. Five analytical samples plus one duplicate sample were taken from MW1, MW2, MW3 and the temporarily installed MW4 on the adjacent property to the West. Results from MW4 were non-detect for Diesel Range Organics (DRO) and indicate that the contaminated groundwater has not moved off of the property to the west. MW2 was also non-detect, while MW1 (1.71 mg/L DRO) and MW3 (0.746 mg/L DRO) contained DRO contamination. MW1 is the only well still above ADEC cleanup levels. Minor issues with lab data and quality control were noted, mainly temperature of samples were our of range at 7C, and RPD was 42%. A quality control review noted that the data is acceptable for intended use, which ADEC agreed. The report and a separate letter from the RP requested a cleanup complete with ICs. ADEC requested more annual groundwater monitoring be completed to better establish a stable or decreasing trend for DRO in groundwater. Next groundwater monitoring event should occur in August 2017. Lisa Griswold
9/27/2016 Update or Other Action ADEC approves via email of proposal to do three quarterly monitoring events instead of three annual events. Lisa Griswold
2/23/2017 Document, Report, or Work plan Review - other Quarterly Groundwater Monitoring Work Plan reviewed and approved on this date. The work plan details plans to sample MW-1 through MW-3 through three quarterly sampling events in an attempt to show a stable or decreasing trend of Diesel Range Organic (DRO) contamination in groundwater. The three wells are to be measured for groundwater depth to establish groundwater direction; sampled via low flow sampling methods; and tested for DRO via AK 102. Lisa Griswold
5/31/2017 Document, Report, or Work plan Review - other Groundwater Monitoring Report approved on this date. The report detailed the sampling of MW1 through MW3 in the first event of three quarterly sampling events in an attempt to show a stable or decreasing trend of Diesel Range Organic (DRO) contamination in groundwater. The three wells were measured for groundwater depth to establish groundwater direction as north-northwest which is consistent with historical data for the site. The three wells were sampled via low flow sampling methods; and tested for DRO via AK 102. Four samples were taken; one from each well, plus a duplicate from MW2. DRO was detected in two out of three wells: MW1 (3.68 mg/L) and MW3 (0.909 mg/L). MW1 was the only well that contained DRO above the ADEC cleanup level of 1.5 mg/L, which is consistent with site history. The approval letter of this report also informed the RP that site management is being transferred to Rodman. Lisa Griswold
5/31/2017 Update or Other Action Site transferred to Rodman. Lisa Griswold
2/6/2018 Document, Report, or Work plan Review - other ADEC reviewed two reports, both titled “Groundwater Monitoring Report, 3102 West 29th Avenue Home Heating Oil Tank, Anchorage, Alaska 99517, ADEC File No. 2100.38.473” (report) dated July 27, 2017 and December 27, 2017 for the Residence - 3102 West 29th Avenue HHOT site in Anchorage, AK. The reports were submitted via email on January 17, 2018 by Environmental Management, Inc. (EMI). The described field effort was conducted on June 19 and September 14, 2017 and generally consisted of collecting groundwater samples from all three monitoring wells for laboratory analysis of diesel range organics (DRO), and managing investigation-derived waste (IDW). These reports are approved. Based on information to date, this site will be evaluated for closure. Amy Rodman
6/6/2019 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 75248 2006 UST contamination. Amy Rodman
7/21/2021 Update or Other Action J. Fix assigned as new Project Manager. Julie Fix

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