Skip to content Skip to content

Alaska Department of Environmental Conservation

You are here: DEC / SPAR / CSP / SPAR Online Services / Contaminated Sites Search / Site Report

Site Report: Commercial Property - 5801 Silverado Way

Site Name: Commercial Property - 5801 Silverado Way
Address: 5801 Silverado Way, Anchorage, AK 99518
File Number: 2100.38.531
Hazard ID: 25892
Status: Cleanup Complete - Institutional Controls
Staff: IC Unit, 9074655229 dec.icunit@alaska.gov
Latitude: 61.166706
Longitude: -149.887815
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

1990-2008 Haliburton Geophysical Service Inc. June 28, 2000(Letter) -Pool Arctic-The Pool Arctic facility is located at 5801 Silverado Way in Anchorage. In July and August 1998, Shannon & Wilson, Inc. conducted a Limited Phase I Environmental Site Assessment that identified three locations with potential environmental concerns: the floor drain system, the sandblasting/paint booth area, and a waste storage area. June 28, 2000(Letter) Pool Arctic Alaska Silverado site ADEC File No. CS 100.220; ADEC concludes that the conditions of 18 AAC 75.380 have been met. The alternative soil cleanup level for diesel range aromatics approved for this site has been achieved and no further remedial action is necessary. 10/13/04 The Landowner is listed with the MOA as North-South Management Services LLC; P.O. Box 505; Ripley, MS, 38663. May 30, 2012 On May 30, 2012 during excavation in preparation for the West Dowling Road Phase I Project near C Street and 5801 Silverado Way contaminated soil and contaminated shallow groundwater were encountered. The road work preparation included the excavation of old fill to 4.5 feet below ground surface (bgs) and peat layers from 4.5 to approximately 12 feet bgs and backfill with road base material to prepare for paving of a new road in 2013. Groundwater was encountered about 3 feet bgs in contact with the contaminated soil. The southern portion of a storage yard located at 5801 Silverado Way was purchased by ADOT for the road right-of-way. In 2012 2,024 cubic yards of fill soil with petroleum odor and staining were stockpiled at the site. The contamination did not appear to be related to past contamination documented at the 5801 Silverado Way property (see Hazard ID/File Nos. 1771 / 2100.38.114 and 24079 / 2100.26.446) that was identified further north and cleaned up to site cleanup levels. The contamination found appears to be related to other past unreported spills at the 5801 Silverado Way property and/or contaminated fill was used in that area. Some sand blasting material was also encountered in the excavated contaminated fill. November 2012 Soil samples were collected from the 2,024 cubic yards of excavated soil stockpiled on-site. Up to 247 mg/kg GRO, 0.0207 mg/kg benzene, 151 mg/kg DRO, 93 mg/kg RRO, 610 mg/kg Chromium, and 330 mg/kg Nickel in the soil samples collected. Low or non-detect concentrations of HVOCs, EDB, PCBs, and PAHs in the soil samples collected. Additional stockpile sampling on December 2012 had total Chromium concentrations ranged from 160 to 490 mg/kg, Hexavalent Chromium from 0.28 to 1.4 mg/kg (0.089 mg/kg 2016 cleanup level), and TCLP Chromium 0.013 to 0.057 mg/l (5 mg/l RCRA). Based on the stockpile sample results this soil was approved to be reused as fill on specific areas of the road project that are not near surface waters or drinking water wells. October 2013 Stockpile samples were collected from soil excavated in 2013. Up to 610 mg/kg chromium, 230 mg/kg nickel, 600 mg/kg DRO, 0.037 mg/kg benzene, 67 mg/kg RRO, 50.9 mg/kg GRO, and below method 2 cleanup levels for VOCs and PAHs in the locations sampled. Based on the stockpile sample results this soil was approved to be reused as fill on specific areas of the road project that are not near surface waters or drinking water wells. Also on October 2013 sidewall and excavation base field screening and laboratory analytical samples were collected from the area excavated in 2013. Up to 170 mg/kg chromium, 60 mg/kg nickel, 463 mg/kg DRO, 0.991 mg/kg benzene, 2,830 mg/kg RRO, non-detect(<146 mg/kg) GRO, and below method 2 cleanup levels for VOCs and PAHs in the locations sampled. In 2015 an estimated 2,700 cubic yards of additional contaminated fill was removed, excavated soil was stockpiled and sampled, four monitoring wells were installed and sampled, and soil samples were collected from the base and sidewalls of the excavation area. Based on the stockpile sample results this soil was approved to be reused as fill on specific areas of the road project that are not near surface waters or drinking water wells. The results of the 2015 excavation base and sidewall sampling have not been submitted to date. The first groundwater monitoring event for the 4 site monitoring wells, conducted on December 2015, had benzene contamination above Table C cleanup levels in one monitoring well, and chromium contamination over Table C cleanup levels in all four monitoring wells. A minimum of four quarters of groundwater monitoring are needed to evaluate seasonal changes in groundwater flow direction and contaminant concentrations. Based on this information additional monitoring wells and/or additional groundwater monitoring may be required. Based on the results of the soil sampling to be conducted on the base and sidewalls of the backfilled excavation, additional corrective action and assessment may be required. Updated 11/4/2021 Confirmation Sampling Report For West Dowling Road Reconstruction Phase II: C Street to Minnesota Drive, dated September 2020 The impacted property was comprised of an existing gravel pad previously used as a storage yard. The pad was approximately 4.0 foot thick and was comprised of contaminated soil that had been imported and placed as fill during the development of this parcel. This property is located to the south of the existing Truckwell of Alaska facility / yard. This impacted parcel (Lot 2) had been subdivided and was purchased by the State of Alaska as part of the property acquisition activities associated with extending West Dowling Road westward. Exceedances of ADEC Soil Cleanup Levels are known to be present in a few places along the floor of the former roadway prism’s excavation and along the excavation’s northern sidewall. A significant amount of contaminated soil was removed from Lot 2 thus, removing the source of contamination from this work area. ADEC approval was obtained to relocate and reuse all of this excavated contaminated soil during the roadway construction project.

Action Information

Action Date Action Description DEC Staff
7/10/2012 Site Added to Database A new site has been added to the database Mitzi Read
7/20/2012 Update or Other Action On May 30, 2012 during excavation in preparation for the West Dowling Road Phase I Project near C Street and 5801 Silverado Way contaminated soil and contaminated shallow groundwater were encountered. The road work preparation included the excavation of fill and peat layers to approximately 12 feet below ground surface (bgs) and backfill with roadbase material to prepare for paving of a new road in 2013. Goundwater was encountered about 3 feet bgs in contact with the contaminated soil. The southern portion of a storage yard located at 5801 Siverado Way was purchased by ADOT for the road right-of-way. Currently 2,024 cubic yards of fill soil with petroleum odor and staining are stockpiled at the site. The consultant noted that based on field observations additional contaminated soil remains in-situ. The source of this contamination is unknown and no analytical samples have been collected yet. The contamination does not appear to be related to past contamination documented at the 5801 Siverado Way property (see Hazard ID/File Nos. 1771 / 2100.38.114 and 24079 / 2100.26.446) that was identified further north and cleaned up to site cleanup levels. The contamination found appears to be related to other past unknown/unreported spills at the 5801 Siverado Way property. Some sand blasting material was also encountered in the excavated contaminated fill. Robert Weimer
7/20/2012 Update or Other Action Email to ADOT's consultant regarding request to reuse excavated contaminated soil in the Dowling Road project. That request is not approved. Because the contamination found is an unknown source the full sampling BTEX, GRO, DRO, RRO, PAH, HVOC, PCB, EDB, 1,2-DCA, and metals is required. The stockpiled soil cannot be evaluated for treatment or disposal until it has been characterized and compared to cleanup levels. The responsible party needs to submit a sampling plan for characterizing the stockpile and a site characterization plan to define the full extent of soil and groundwater contamination for this site. ADEC requested contact information for ADOT. Robert Weimer
7/25/2012 Potentially Responsible Party/State Interest Letter DEC PRP letter to Raintree Properties LLC. The letter requests a completed "Request of Information Questionnaire" by 8/25/12. The DEC letter also notifies Raintree Properties LLC about cost recovery for State of Alaska oversight costs. Robert Weimer
7/26/2012 Site Visit Site visit to check on the condition of the stockpile. Robert Weimer
8/15/2012 Update or Other Action DEC receives information from Raintree Properties LLC regarding the "Request of Information Questionnaire". Robert Weimer
8/21/2012 Update or Other Action Discussed site with ADOT contact. He will have their contractors consultant submit a work plan for the characterization of the exisiting stockpile. He will also provide past site information they have in their files regarding potential sources of the contamination. Robert Weimer
8/27/2012 Document, Report, or Work plan Review - other ADEC review of the August 27, 2012 stockpile sampling plan. ADEC requested a revised work plan with the following modifications: Section 3.1 - Need to specify the frequency of field screening (one per 10 cubic yards) and how the field screening samples will be collected from such a large stockpile. The field screening samples need to be collected throughout (including near the bottom in the center of the pile) the stockpile, all at least 18 inches into the pile. I recommend segregating the stockpile into 13 piles of approximately 156 cubic yards, with one analytical sample collected from the highest of 16 field screening locations in each pile. Section 3.2 - Need to specify how the confirmation soil samples will be collected after obtaining field screening readings. Section 4.0 - You may want to consider just analyzing the highest 4 field screening locations (plus one duplicate) first to see what type of contamination we have in the 2,024 cubic yards. The other 9 samples (plus one duplicate) could be held in the lab. Based on the results of the first 4 samples we may be able to eliminated PAH and EDB/1,2-DCA analysis for the rest of the samples. Also based on the first 4 samples DOT may decide that all of the excavated soil will need to be treated, in which case we would not need to have the other 9 samples analyzed. Section 4.0 - In order to detect down to cleanup levels EPA 8011 or EPA 504.1 (both field preserved in hexane) should be used for the EDB analysis. Section 6.0 - Need to notify the DEC project manager at least 3 days prior to conducting field work. Robert Weimer
9/21/2012 Document, Report, or Work plan Review - other The September 2012 Sampling Analysis Work Plan is approved with the following conditions: 1. The field sampling needs to be done in accordance with the May 2010 Draft Field Sampling Guidance and 18 AAC 75. The field notes need to be of sufficient detail to demonstrate this. 2. The stockpile field screening samples need to be collected from throughout and a minimum of 18 inches into the 156 cubic yard stockpiles. 3. The analytical sample needs to be collected from the area of most likely contamination (based on field readings and observations) within the 156 cubic yard stockpile. The work plan calls for excavating the 2,024 cubic yards and placing it into 156 cubic yard piles, then collecting 16 field screening samples from each pile, the collecting 1 analytical sample at the area of most likely contamination in each pile. Robert Weimer
12/11/2012 Site Characterization Report Approved On November 1-2, 2012 thirteen soil samples (and two duplicates) were collected from the 2,024 cubic yards of excavated soil stockpiled on-site. Up to 247 mg/kg GRO, 0.0207 mg/kg benzene, 151 mg/kg DRO, 93 mg/kg RRO, 610 mg/kg Chromium, and 330 mg/kg Nickel in the soil samples collected. Low or non-detect concentrations of HVOCs, EDB, PCBs, and PAHs in the soil samples collected. Because the Chromuim samples are over 100 mg/kg they could fail RCRA TCLP of 5 mg/l. They need to collect representative samples and have them analyzed for TCLP Chromium. The soil is currently covered and stored in the Dowling Road right-of-way where it was excavated. Robert Weimer
12/11/2012 Meeting or Teleconference Held Discussed sample results with DOT. The lab confirmed that they have the samples but there is not enough volume to conduct TCLP analysis. DOT will have their consultant submit a work plan to collect soil samples for TCLP and total Chromium analysis. If soils fail TCLP it will be hazardous waste that will need to be disposed of at an out of state RCRA landfill. If soils pass TCLP they will need to analyzed for Chromium +6 to compare to DEC cleanup levels. DEC will evaluate the results to determine if the excavated soil can be used in the planned Dowling Road project separated from water wells, surface waters, and no used near the surface. Robert Weimer
12/11/2012 Exposure Tracking Model Ranking Initial ranking with ETM completed for source area id: 79373 name: Dowling Road Extension Robert Weimer
12/12/2012 Site Characterization Workplan Approved Approved work plan to collect soil samples for TCLP, Chromium +6, and total Chromium analysis. DEC will evaluate the results to determine if the excavated soil can be used in the planned Dowling Road project separated from water wells, surface waters, and no used near the surface or whether the soil will need to disposed of at a permitted landfill. Robert Weimer
2/11/2013 Update or Other Action Review of the preliminary results of the December 2012 sampling. Total Chromium concentrations ranged from 160 to 490 mg/kg (25 mg/kg cleanup level), Hexavalent Chromium from 0.28 to 1.4 mg/kg (25 mg/kg cleanup level), and TCLP Chromium 0.013 to 0.057 mg/l (5 mg/l RCRA). Based on the sample results DEC may be able to approve the soil for reuse in the road project, although it will probably be restricted to under pavement, with the appropriate separation distance to surface waters and drinking water wells and institutional controls on the area where the contaminated soil is placed. On February 11, 2013 DEC requested a completed hard copy report for the December work (all we have received was a CD of the raw data and photos), a Conceptual Site Model, a drinking water well search, proposed disposal location for the contaminated soil showing separation distance to drinking water wells and surface waters, and the historic information DOT collected regarding the probable source of the contaminated soil. Robert Weimer
5/20/2013 Site Visit Site visit to check on the condition of the stockpile. Robert Weimer
6/26/2013 Update or Other Action DEC email to DOT that DEC has no objection to relocating the existing contaminated soil pile to the intermediate stockpile location depicted on the figure provided (just to the west). Robert Weimer
6/26/2013 Update or Other Action DEC requests notification when DOT plans to begin excavating the remaining contaminated soil. DEC reminded DOT that they will need to submit a work plan and have it approved prior to excavating additional contaminated soil. The work plan would include soil storage, segregation, field readings, analytical samples of the excavated material, and field readings and analytical samples from the base and sidewall of the excavation. There will also need to be a work plan for assessing the area where contaminated soil was excavated previously. Robert Weimer
6/28/2013 Site Visit Site visit to check on the condition of the stockpile. Robert Weimer
7/8/2013 Update or Other Action As requested back on February 11, 2013, DEC has not yet received completed hard copy report for the December 2012 work, a Conceptual Site Model, a drinking water well search, and proposed disposal location map for the contaminated soil showing separation distance to drinking water wells and surface waters. DEC will need this information to complete the review of the request to use the soil as fill in the road project. Robert Weimer
9/4/2013 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 79373 Dowling Road Extension . Robert Weimer
9/23/2013 Document, Report, or Work plan Review - other DEC provided comments on the sampling plan received on September 16, 2013. The plan calls for taking field screening and analytical samples to assess for remaining contamination for the area excavated in 2012. DEC comments included needing a site map, field screening and analytical samples from the base of the former excavation, not using a vac truck to remove soil from within 4 feet of an area where volatile soil samples are to be collected. The DEC also noted that long term groundwater monitoring wells will need to be installed and sampled to characterize the nature and extent of any remaining groundwater contamination. Groundwater was encountered at 3 feet below ground surface during the 2012 soil excavation. Robert Weimer
9/24/2013 Document, Report, or Work plan Review - other The August 2013 "Sampling and Analysis Plan" along with the modifications discussed in the September 24, 2013 letter is approved for the proposed 2013 western excavation area and its excavated soil under the following conditions: 1. The stockpile, excavation sidewall, and excavation bottom field screening and analytical samples are to be conducted in accordance with the May 2010 Draft Field Sampling Guidance. 2. All excavated soil is to be stockpiled on a bermed liner and covered in accordance with 18 AAC 75. 3. A complete hard copy final report in accordance with 18 AAC 75 is to be submitted by December 1, 2013. 4. For stockpiles: The highest field reading locations sampled are to be also analyzed for PAHs and VOCs. Minimum of 1 per 10 analytical samples collected from the stockpiles, plus one duplicate PAH and VOC sample. 5. For sidewalls: The highest field reading locations sampled are to be also analyzed for PAHs and VOCs. Minimum of 1 per 10 total sidewall analytical samples collected. 6. For base of excavation: The highest field reading locations sampled are to be also analyzed for PAHs and VOCs. Minimum of 1 per 10 analytical samples collected from the base of the excavation. 7. A separate plan is to be submitted for the 2012 excavation area and groundwater monitoring wells. Robert Weimer
11/12/2013 Document, Report, or Work plan Review - other Approve request to over excavate and stockpile areas in the base of the excavation that exceed cleanup levels. They are to collect base and sidewall confirmation samples at each area based on highest field screening locations. Robert Weimer
11/12/2013 Update or Other Action Received preliminary results of the base and sidewall excavation sampling. Up to 0.991 mg/kg benzene and 356 mg/kg DRO remaining. 15 (2 sidewall and 13 base) of the 52 sampled locations still exceed cleanup levels. Robert Weimer
11/15/2013 Update or Other Action DEC requests the BTEX sample results, site figure, field notes, DRO chromatograms, DRO results for FL31A, and BTEX results for FL26 for the sampling conducted between 10/15/13 and 10/21/13. DOT's consultant said he will submit all of the information in the sampling report to be submitted in a few weeks. Robert Weimer
11/27/2013 Document, Report, or Work plan Review - other Between 10/9/13 and 10/19/13 twelve stockpile samples plus one duplicate were collected from soil excavated in 2013. Up to 610 mg/kg chromium, 230 mg/kg nickel, 600 mg/kg DRO, 0.037 mg/kg benzene, 67 mg/kg RRO, 50.9 mg/kg GRO, and below method 2 cleanup levels for VOCs and PAHs in the locations sampled. Need TCLP testing and chrome +6 results for the chromuim samples that are over 100 mg/kg. Site figures, project narrative, and field notes are missing from the report. Robert Weimer
12/2/2013 Update or Other Action Talked with ADOT, they will submit the missing information including TCLP testing and chrome +6 results for the chromuim samples that are over 100 mg/kg. Site figures, project narrative, and field notes are missing from the report. Also still missing a complete report for the 2012 sampling, a drinking water well search, and proposed disposal location map for the contaminated soil showing separation distance to drinking water wells and surface waters. Robert Weimer
1/7/2014 Site Visit Site visit to observe site conditions and locations of stockpiles. Robert Weimer
7/3/2014 Update or Other Action Email to DOT and their consultant. DEC still has not received in the missing information we discussed back on December 2, 2013. The missing information includes TCLP testing and chrome +6 results for the chromium samples that are over 100 mg/kg. Site figures, project narrative, and field notes are missing from the report. I am also still missing a complete report for the 2012 sampling, a drinking water well search, and proposed disposal location map for the contaminated soil showing separation distance to drinking water wells and surface waters. DEC needs all of that information before we can review a request to reuse/dispose of any soil or peat that has contamination above default method 2 cleanup levels. The July 2, 2014 Schedule letter proposes embanking approximately 2700 cubic yards of contaminated soil in August 2014, this is not approved. Robert Weimer
7/17/2014 Meeting or Teleconference Held Meeting with DOT. Based on the additional information provided by the consultant ADEC has no objection to reusing the stockpiled material in the right of way in accordance with the July 7, 2014 submittal. The peat material is not approved for reuse. Robert Weimer
10/14/2014 Document, Report, or Work plan Review - other Between 10/15/13 and 11/13/13 sidewall and excavation base field screening and laboratory analytical samples were collected from the area excavated in 2013. Up to 170 mg/kg chromium, 60 mg/kg nickel, 463 mg/kg DRO, 0.991 mg/kg benzene, 2,830 mg/kg RRO, <146 mg/kg GRO, and below method 2 cleanup levels for VOCs and PAHs in the locations sampled. Need TCLP testing and chrome +6 results for the chromium samples that are over 100 mg/kg (SW17). All of the floor VOC and most of the BTEX samples collected on the floor of the excavation had detection limits that exceeded cleanup levels. Data quality problems with twelve sidewall samples (SW6-17) and fifteen bottom samples (FL 1,3,4,10,12,13,15,16,19,26,27,28,29,30,31) were not properly preserved (over temperature/not submerged in methanol) so they are considered biased low and can't be used for final confirmation samples. Also the all areas that were over excavated (2 sidewall and 13 bottom locations) in 2013 did not have the amount of required field screening to determine where to collect laboratory analytical samples. Robert Weimer
10/15/2014 Document, Report, or Work plan Review - other DEC letter regarding the August 2014 "Sampling Analysis Plan for Remaining Insitu Soils at Tract 2B, Silverado Subdivision, Plat 80-111" is not approved for the assessment of the eastern portion. A separate work plan for that area is requested by November 1, 2014. That work plan needs to include field screening and confirmation sampling of the former excavation base and sidewalls in accordance with the DEC May 2010 Draft Field Sampling Guidance and the related comments below. Also long-term groundwater monitoring wells will be required in the future, under a separate work plan to be submitted by March 1, 2015. The August 2014 "Sampling Analysis Plan for Remaining Insitu Soils at Tract 2B, Silverado Subdivision, Plat 80-111" is approved for the assessment of the western portion under the following conditions: 1. All excavated soil is to be segregated based on field reading and observations into separate lined, bermed, and covered stockpiles in accordance with the liner and storage specifications in 18 AAC 75. 2. Once the stockpiles are completed they are to have field screening and analytical samples collected in accordance with the DEC May 2010 Draft Field Sampling Guidance. 3. For each stockpile: the highest field screening location is also analyzed for PAHs and VOCs, including a duplicate. If there are more than 10 analytical locations in a stockpile additional samples at the next highest field screening location are to be analyzed for PAHs and VOCs for every 10 analytical samples or part thereof. 4. For the sidewalls: the highest field screening location is also analyzed for PAHs and VOCs, including a duplicate. If there are more than 10 analytical locations in a stockpile additional samples at the next highest field screening location are to be analyzed for PAHs and VOCs for every 10 analytical samples or part thereof. 5. For base of the excavation: the highest field screening location is also analyzed for PAHs and VOCs, including a duplicate. If there are more than 10 analytical locations in a stockpile additional samples at the next highest field screening location are to be analyzed for PAHs and VOCs for every 10 analytical samples or part thereof. 6. Complete copies of field notes are to be provided with the report. 7. The report and field notes need to document that for each sidewall, that each side wall soil layer (at the top of tighter soil types, and the bottom of more porous layers) has field screening readings to demonstrate the layer(s) most likely to be contaminated. The additional sidewall field reading will be from the appropriate depth within those layer(s). 8. The report needs to meet the reporting requirements in 18 AAC 75. Here is a link to the DEC guidance on what information is needed in the report. http://dec.alaska.gov/spar/csp/guidance/site-characterization-wp&r.pdf 9. If an area of contamination is encountered that does not appear to be consistent with the contamination previously identified (such as a new source area, used oil, solvent odors, etc…) that soil needs to be placed on a separate bermed liner and covered, with characterization samples collected in accordance with the May 2010 Draft Field Sampling Guidance as an unknown source from that stockpile and the excavation base and sidewalls where those soils were removed. 10. DEC be notified prior to conducting any field screening or sampling work. Robert Weimer
10/23/2014 Potentially Responsible Party/State Interest Letter DEC PRP letter to Nabors Industry. The DEC letter notifies Nabors Industry about cost recovery for State of Alaska oversight costs. Robert Weimer
11/3/2014 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 79373 Dowling Road Extension . Robert Weimer
11/5/2014 Meeting or Teleconference Held Meeting with DOT and their consultant to discuss past and future site work. They will submit a work plan for further assessment work for the bottom and sidewalls of the excavated areas and the installation and sampling of monitoring wells. Robert Weimer
11/19/2014 Offsite Soil or Groundwater Disposal Approved ADEC has no objection to removing the clean overburden that was placed over the liner in 2013 and hauling it to the clean disposal area. Robert Weimer
11/21/2014 Document, Report, or Work plan Review - other ADEC review letter to ADOT for the Tellus, Ltd. June 2014 “Field Summary Report for West Dowling Road Reconstruction” for the Commercial Property – 5801 Silverado Way contaminated site. The report documents site work conducted in between October 2013 and November 2013. As noted in ADEC’s July 8, 2014 email to ADOT and as discussed in the meeting with ADOT on November 5, 2014 the assessment work conducted by Tellus Ltd. in October and November 2013 was not done in accordance with the conditionally approved August 2013 work plan and ADEC regulatory (18 AAC 75) requirements: 1. Fifteen bottom samples (FL 1,3,4,10,12,13,15,16,19,26,27,28,29,30,31) collected between 10/6/2013 and 10/19/2013 were not properly preserved, they were not fully submerged in methanol. 2. Twelve sidewall samples (SW6-SW17) collected on 10/19/2013 were not kept at the required temperature for the 2 days from sampling until they were submitted to the lab. 3. All areas that were over excavated (2 sidewall and 13 bottom locations) in 2013 did not have the amount of required field screening samples to determine where to collect laboratory analytical samples. 4. All areas that were over excavated (2 sidewall and 13 bottom locations) in 2013 did not have the amount of required number of base and sidewall analytical samples. The report and field notes did not document the size of the areas that were overexcavated. 5. The Data Quality and the Conclusion sections of the report did not identify all of the data quality problems with laboratory analytical samples collected. 6. The Laboratory Data Review Checklist included with the report did not identify all of the data quality problems with laboratory analytical samples collected. 7. The sidewall sample collected at SW17 had 170 mg/kg Chromium but TLCP testing of that sample was not conducted as specified in the approved work plan. Because of these data quality problems the side wall and floor samples collected can’t be used to demonstrate that those areas meet site cleanup levels. Additional assessment in accordance with ADEC regulatory (18 AAC 75) requirements and an approved site specific work plan for those areas is required. ADEC is currently reviewing the November 2014 work plan for the assessment of the 2012 and 2013 excavation areas and the assessment of the areas to be excavated in the Winter of 2014/Spring 2015. ADEC will be requesting that the November 2014 work plan be revised to also include the assessment of the excavation areas with data quality problems discussed in this letter. Robert Weimer
11/25/2014 Document, Report, or Work plan Review - other The Alaska Department of Environmental Conservation (ADEC) has reviewed the Tellus, Ltd. November 2014 “Sampling Analysis Plan for Remaining Insitu Soils” for the Commercial Property – 5801 Silverado Way contaminated site. The proposed work plan is not approved. The ADEC requests a revised work plan with the following modifications: 1. All excavated soil is to be segregated based on field reading and observations into separate lined, bermed, and covered stockpiles in accordance with the liner and storage specifications in 18 AAC 75. 2. Once the stockpiles are completed they are to have field screening and analytical samples collected in accordance with the ADEC May 2010 Draft Field Sampling Guidance. 3. All analytical samples are to be analyzed for BTEX, DRO, GRO, RRO, Chromium, and Nickel. Any sample with 100 mg/kg or greater Chromium is to have TCLP analysis and Chromium +6 results. 4. For each stockpile: the highest field screening location is to be also analyzed for PAHs and VOCs, including a duplicate. If there are more than 10 analytical stockpile samples then additional samples at the next highest field screening location are to be analyzed for PAHs and VOCs for every 10 analytical samples or part thereof. 5. For the sidewalls: the highest field screening location is also to be analyzed for PAHs and VOCs, including a duplicate. If there are more than 10 analytical sidewall samples then additional samples at the next highest field screening location are to be analyzed for PAHs and VOCs for every 10 analytical samples or part thereof. 6. For base of the excavation: the highest field screening location is also to be analyzed for PAHs and VOCs, including a duplicate. If there are more than 10 analytical base samples in the excavation then additional samples at the next highest field screening location are to be analyzed for PAHs and VOCs for every 10 analytical samples or part thereof. 7. The report and field notes need to document that for each sidewall, that each side wall soil layer (at the top of tighter soil types, and the bottom of more porous layers) has field screening readings to demonstrate the layer(s) most likely to be contaminated. The additional sidewall field readings will be from the appropriate depth within those layer(s). 8. The report needs to meet the reporting requirements in 18 AAC 75. Here is a link to the ADEC guidance on what information is needed in the report. http://dec.alaska.gov/spar/csp/guidance/site-characterization-wp&r.pdf Robert Weimer
11/25/2014 Document, Report, or Work plan Review - other The Alaska Department of Environmental Conservation (ADEC) has reviewed the Tellus, Ltd. November 2014 “Sampling Analysis Plan for Remaining Insitu Soils” for the Commercial Property – 5801 Silverado Way contaminated site. The proposed work plan is not approved. The ADEC requests a revised work plan with the following modifications: 9. If an area of contamination is encountered that does not appear to be consistent with the contamination previously identified (such as a new source area, used oil, solvent odors, etc…) that soil needs to be placed on a separate bermed liner and covered, with characterization samples collected in accordance with the ADEC May 2010 Draft Field Sampling Guidance as an unknown source from that stockpile and the excavation base and sidewalls of where those soils were removed. 10. For the Eastern Portion (2012 excavation) of Lot 2 we need at least 10 soil borings with laboratory analytical soil samples collected from the top two feet of soil beneath the fill in each soil boring. The entire length of the north and south sidewalls of this area need to be field screened and have analytical samples collected in accordance with the ADEC May 2010 Draft Field Sampling Guidance. The work plan needs to specify whether the sidewall field screening and analytical sampling will be conducted with borings or by trenching, and document that the samples were collected outside of the 2012 backfill material. 11. For the Western Portion (2013 excavation) of Lot 2 the entire length of the north and south sidewalls of this area need to be field screened and have analytical samples collect in accordance with the ADEC May 2010 Draft Field Sampling Guidance. The entire base of this area needs to be field screened and have analytical samples collect in accordance with the ADEC May 2010 Draft Field Sampling Guidance. 12. For the portion of the remaining contaminated fill west of 2013 excavation (planned to be excavated in the Winter of 2014/Spring 2015) the entire length of the west, north, and south sidewalls of this area will need to be field screened and have analytical samples collect in accordance with the ADEC May 2010 Draft Field Sampling Guidance. The entire base of this area needs to be field screened and have analytical samples collect in accordance with the ADEC May 2010 Draft Field Sampling Guidance. 13. If after receiving the analytical results from a sidewall sample additional soil is to be excavated from that area to remove the remaining contamination, then field screening and analytical samples need to be collected from the base and sidewalls of that area in accordance with the ADEC May 2010 Draft Field Sampling Guidance. 14. If after receiving the analytical results from an excavation base sample additional soil is to be excavated from that area to remove the remaining contamination, then field screening and analytical samples need to be collected from the base and sidewalls of that area in accordance with the ADEC May 2010 Draft Field Sampling Guidance. 15. As discussed in the November 5, 2014 meeting ADEC is requesting a minimum of 4 monitoring wells to be installed near the four corners of the contaminated fill area outside of the excavated area. The work plan needs to include details on monitoring well construction (including the interval of the well screen) and development in accordance the ADEC September 2013 Monitoring Well Guidance. Based on the results of the groundwater monitoring and seasonal groundwater flow direction additional monitoring wells may be required to characterize the nature and extent of the potential groundwater contamination at this site. 16. The work plan needs to include a figure showing the correct location of all of the past sidewall and excavation base field screening and analytical samples. The figure submitted is missing the analytical sample locations for samples (SW19, SW20, SW21, and FL 01 through FL 18). The figure also includes locations where laboratory results were not submitted (FL 32, FL 33, and FL 34). Robert Weimer
4/3/2015 Document, Report, or Work plan Review - other The Alaska Department of Environmental Conservation (ADEC) has reviewed the Tellus, Ltd. March 2015 “Sampling Analysis Plan for Remaining Insitu Soils” for the Commercial Property – 5801 Silverado Way contaminated site. The proposed work plan did not address all of the comments in the ADEC email of February 20, 2015. The proposed work plan is not approved. The ADEC requests a revised work plan with the following modifications: 1. The work plan needs to include specific details on how the assessment work will be conducted., just stating it will be done in accordance with the ADEC’s May 2010 Draft Field Sampling Guidance is not adequate. The work plan needs to detail as to how the analytical samples will be collected based on field readings and site observations. 2. The work plan needs specific details as to how the stockpiles will be constructed (liner thickness, height of berms, size of stockpiles, height of soil), covered (cover material, when/how soon it will be covered), and maintained. Also need details on how the stockpiled soil field screening (minimum of 18 inches into the stockpile and throughout, including the base of the stockpile) and analytical sampling will be conducted. How will the excavated soils be segregated? How will unknown contaminated soil be stored and segregated? 3. The work plan needs specific details as to how the field screening and analytical sampling is going to be conducted for the sidewalls, and base of the excavation. This includes how much exposed soil is removed prior to collecting field screening and analytical samples. 4. The work plan needs specific details as to how the field screening and analytical sampling is going to be conducted for the soil borings. This includes that analytical sample jars will be filled immediately and before placing soil in the field screening Ziploc bag. 5. The work plan needs to include a figure showing the locations where laboratory results were not submitted (FL 32, FL 33, and FL 34). 6. The work plan needs to clarify whether groundwater samples will be collected as part of this site work. 7. The work plan does not specify how and where the peat soil from the 7 locations in the western portion (2013 soils) of Lot 2 is to be stored and sampled. Robert Weimer
4/7/2015 Document, Report, or Work plan Review - other The Alaska Department of Environmental Conservation (ADEC) has reviewed the Tellus, Ltd. April 2015 “Sampling Analysis Plan for Remaining Insitu Soils” for the Commercial Property – 5801 Silverado Way contaminated site. The proposed work plan did not address all of the comments in the ADEC email of April 3, 2015. The proposed work plan is not approved. The ADEC requests a revised work plan with the following modifications: 1. Based on an estimated 2,700 cubic yards of stockpiled material that would require 16 analytical samples. ADEC recommends the soil be segregated into 16 stockpiles (one for the 7 locations in the western portion, and 15 roughly equal sized for the other excavated soils) for each analytical sample. After the stockpiles are placed in the cell need at least one field screening location per 10 cubic yards in each stockpile (with at least 5 field screening locations for stockpiles under 50 cubic yards). Need details on how the stockpiled soil will be field screening (minimum of 18 inches into the stockpile and throughout, including the base of the stockpiled material) and how the analytical sampling will be conducted (return to the field screening location, expose fresh soil, immediately fill volatile sample jar, etc..). 2. The work plan needs specific details as frequency of the field screening and analytical sampling that is going to be conducted for the sidewalls, and base of the excavation. 3. The work plan needs to specify how the groundwater monitoring wells will be purged just prior to sampling, water quality parameters measured during purging, how it will be determined that the well was adequately purged, how and with what the monitoring wells will be sampled, that the sampling interval will be within the top foot of the water column, and what the groundwater samples will be analyzed for. Robert Weimer
4/13/2015 Document, Report, or Work plan Review - other The Alaska Department of Environmental Conservation (ADEC) has reviewed the Tellus, Ltd. April 2015 “Sampling Analysis Plan for Remaining Insitu Soils” for the Commercial Property – 5801 Silverado Way contaminated site provided on April 9, 2015. The proposed work plan did not address all of the comments in the ADEC email of April 7, 2015. The proposed work plan is not approved. The ADEC requests a revised work plan with the following modifications: 1. Section 3.4 (Soil Stockpiling) of the work plan was not updated with the changes proposed in comment 1 of the April 9, 2015 letter. Please provide a work plan with the proposed changes. 2. The groundwater monitoring analysis needs to include nickel and chromium. 3. Due to the loss of volatiles for samples collected with a peristaltic pump, ADEC requests that another sampling device be used that minimizes the loss of volatiles (such as a bladder pump, positive pressure pump, or gear pump) for the volatile (BTEX, GRO, VOC) groundwater sample collection. When samples are collected for laboratory analysis, the pump’s tubing must be disconnected from any “T” connector with a valve, flow-through-cell, and constriction device on the tubing. During laboratory analytical sample collection do not use a constricting device on the sample tubing to reduce the flow rate because the constrictor will cause a pressure difference in the water column and a loss of VOCs and dissolved gasses. 4. The monitoring wells need to be surveyed in and the depth to groundwater needs to be measured prior to purging so the groundwater flow direction can be determined and documented in the report. 5. Depth to groundwater at the time of the sampling needs to be measured and documented in the report and field notes to demonstrate that the intake for the sampling device is as close as possible (and within 1 foot) to the soil/water interface at the time of the sampling. 6. The work plan needs to specify what is going to be done with the purge water (how and where it will be stored, how and where it will be treated/disposed of). Usually the treatment/disposal of purge water is under a separate request after receiving analytical results back from the lab. Robert Weimer
4/16/2015 Site Characterization Workplan Approved ADEC approves April 14, 2015 revised work plan for the installation and sampling of monitoring wells and soil borings, the excavation of contaminated and potentially contaminated soil, the stockpiling and sampling of those soils, and the collection of confirmation soil samples from the base and sidewall of the excavated area. Robert Weimer
4/23/2015 Site Visit Site visit to discuss monitoring well locations. Robert Weimer
5/1/2015 Site Visit Site visit to observe current site work and to discuss future site work. Robert Weimer
5/6/2015 Document, Report, or Work plan Review - other Because of the difficulty of collecting samples from the excavation base with the water entering the excavation, ADOT is requesting to backfill the excavation with clean fill and assess the base of the excavation with soil borings. ADEC has no objection to backfilling the excavation and assessing the base of the excavation with soil borings. ADEC requests a minimum of 15 soil borings for this area: 11 at the following locations below where contamination or the highest field readings were identified in the past (FL 5A, FL 23AD, FL 26A, FL 28A, FL 21, FL 22, FL 23, FL 10, FL 19, FL 27, and FL 30) and 4 other borings placed to cover the rest of the excavation. ADEC requests a revised boring map showing the borings to cover these locations. At least two sample locations will need VOCs, PAHs with one duplicate for VOCs and PAHs. Two of the other sampling locations will need a duplicate sample for BTEX, GRO, DRO, RRO, Nickel and Chromium. Robert Weimer
6/2/2015 Document, Report, or Work plan Review - other ADEC review of May 2015 stockpile sampling report. The stockpile sampling report is incomplete. None of the stockpiled soils are currently approved for reuse. The DEC requests a revised report that includes the following information: 1. PAH and VOC sampling results are missing. The approved work plan specified that 10% of the stockpile samples would include this analysis. 2. The report and field notes need to document the depth that the field screening and analytical samples were collected, including the depth of the stockpile at each location. 3. The report need to provide detail on how the field screening and analytical samples were collected and how the analytical samples were collected after getting field screening results. 4. The field notes document that the volume of soil stockpile as 2,556 cubic yards. The report says 2,700 cubic yards. 5. Missing a site diagram that shows the location of the field screening and analytical samples. 6. Need a map showing the location that soil is proposed to be reused including distance to nearest surface waters and drinking water wells. Robert Weimer
6/18/2015 Document, Report, or Work plan Review - other April 30 - May 1, 2015 stockpile sampling. Lots 1, 2, 5, 6, 7, 13, 14, and 15 contain DRO contamination (260 mg/kg to 570 mg/kg) over cleanup levels. Lot 6 contains RRO contamination over cleanup levels at 13,000 mg/kg. The laboratory identified the soils from lots 1 through 7 as being diesel. The other lots (13, 14, 15) also appear to be diesel fuel based the peat samples with similar % solids being non-detect (<52 mg/kg for DRO). Lots 1, 2, 3, and 6 contain chromium (33 to 45 mg/kg) over cleanup levels. Robert Weimer
6/29/2015 Document, Report, or Work plan Review - other A revised stockpile sampling report was provided on June 25, 2015. Based on the information provided ADEC has no objection to reusing Stockpile Lots 4,8,9,10,11, and 12 in the slope area of the road project proposed. The other Stockpile Lots (1,2,3,5,6,7,13,14, and 15) are not approved for reuse because they contain DRO, RRO, and/or chromium over cleanup levels. ADEC requests a treatment/disposal plan for those soils be submitted by August 1, 2015. Robert Weimer
7/9/2015 Document, Report, or Work plan Review - other Based on the information provided ADEC has no objection to reusing Stockpile Lots 4,8,9,10,11, and 12 in the slope area proposed. Stockpile Lots 1,2,3,5,7,13, 14, and 15 are approved to be reused in the slope area proposed on the condition that soon (within a few days) after placement they are covered with at least 1 foot of clean material or the material from Stockpile Lots 4,8,9,10,11, and 12, then hydroseeded to stabilize the slope soon (within a few days) after that. ADEC requests that documentation be submitted when this work has been completed and where (location and approximate depth)that Stockpile Lots 1,2,3,5,7,13, 14, and 15 soil has been placed. Because of the high concentrations of DRO and RRO Stockpile Lot 6 is not approved for reuse. ADEC requests a treatment/disposal plan for those soils be submitted by August 15, 2015. Robert Weimer
8/12/2015 Document, Report, or Work plan Review - other ADEC has no objection to assessing the base of the western half of lot 2 with soil borings. ADEC requests a minimum of 15 borings like the eastern half of lot 2. The borings need to include the most contaminated areas (lots 16, 17, 18, 19, 20, 28, and 33), with the rest of the borings spread out over the rest of the areas. ADEC requests a revised figure showing where each of the lots were excavated and the proposed soil boring locations. Robert Weimer
8/18/2015 Document, Report, or Work plan Review - other ADEC has no objection to characterizing the base of the excavation with borings through the backfill in order to obtain soil samples from the previously exposed native silt at the base of the excavation. The field notes and boring logs need to document that the samples were collected the within top two feet previously exposed native silt at the base of the excavation. All of the samples will need to be analyzed for BTEX, GRO, DRO, RRO, Nickel, and Chromium. At least two sample locations (Boring 17 and 33) will need VOCs, PAHs with one duplicate (Boring 33) for VOCs and PAHs. At least two sample locations (Boring 16 and 28) will need a duplicate sample for BTEX, GRO, DRO, RRO, Nickel and Chromium. Any sample with 100 mg/kg or greater Chromium will need TCLP analysis and Chromium +6 results. Robert Weimer
8/27/2015 Document, Report, or Work plan Review - other Based on the information provided ADEC has no objection to reusing Stockpile Lots 34, 35, 39, 41, 42, 43, and 44 in the slope areas proposed. Stockpile Lots 6, 16 through 27, 29 through 33, 36, 37, 38, and 40 are approved to be reused in the slope areas proposed on the condition that soon (within a few days) after placement they are covered with at least 1 foot of clean material or the material from Stockpile Lots 34, 35, 39, 41, 42, 43, and 44, then hydroseeded to stabilize the slope soon (within a few days) after that. ADEC requests that documentation be submitted when this work has been completed and where (location and approximate depths) that Stockpile Lots 6, 16 through 27, 29 through 33, 36, 37, 38, and 40 soil has been placed. Because of the high concentrations of GRO (6,900 mg/kg) Stockpile Lot 28 is not approved for reuse. ADEC requests a treatment or resampling (to demonstrate that the GRO was introduced in the lab) work plan for those soils be submitted by September 15, 2015. Robert Weimer
9/25/2015 Document, Report, or Work plan Review - other Based on the information provided ADEC has no objection to reusing Stockpile Lot 28 in the slope areas proposed in June 8, 2015, July 31, 2015, or August 19, 2015 on the condition that soon (within a few days) after placement of the Lot 28 soils they are covered with at least 1 foot of clean material then hydroseeded to stabilize the slope soon (within a few days) after that. ADEC requests that documentation be submitted when this work has been completed and where (location and approximate depths) that Stockpile Lots 28 soil has been placed. Robert Weimer
4/11/2016 Update or Other Action On April 7, 2016 the consultant attempted to collect quarterly groundwater sampling event, but found that all 4 monitoring wells were frozen or partially frozen so groundwater samples were not collected. ADEC requested that additional attempts be made at the end of April and early May to collected the quarterly groundwater monitoring samples. Robert Weimer
8/16/2016 Document, Report, or Work plan Review - other December 1-2, 2015 groundwater monitoring event. Groundwater samples were collected from the 4 site monitoring wells. Depth of water was 4.35 to 6.7 feet below top of well casing, the well casings are above the ground. Depth to groundwater below ground surface was not calculated. Up to 5.6 ug/l benzene, 44 ug/l chromium, and 49 ug/l nickel in the 4 groundwater samples collected. The samples for TEX, GRO, DRO, RRO, PAHs, other VOCs were non-detect. The monitoring well with the highest concentrations is monitoring well MWB which is location on the southeast corner. Groundwater flow direction was to the southwest to northeast this monitoring event. The monitoring wells were purged prior to sampling with a positive pressure hurricane pump. The report notes that the intake of the pump was within the top foot of the water column at the time of sampling, but this was not documented in the field notes. Robert Weimer
9/29/2016 Document, Report, or Work plan Review - other June 9-10, 2016 groundwater monitoring event. Groundwater samples were collected from the 4 site monitoring wells. Depth of water was 5.0 to 7.6 feet below top of well casing, the well casings are above the ground. The bottom of the wells were still frozen. Depth to groundwater below ground surface was not calculated. Up to 8.1 ug/l benzene, 0.46 mg/l DRO, 0.44 mg/l RRO, 5.2 ug/l chromium, and 19 ug/l nickel in the 4 groundwater samples collected. The samples for TEX, GRO, PAHs, other VOCs were non-detect. The monitoring well with the highest concentrations is monitoring well MWD which is located on the northwest corner. Groundwater flow direction was to the southeast to southwest this monitoring event. The monitoring wells were purged prior to sampling with a positive pressure hurricane pump. Monitoring well MWC volatile sample results may be biased low because the sample was collected using a bailer. The report notes that the intake of the pump was within the top foot of the water column at the time of sampling, but this was not documented in the field notes. Robert Weimer
6/21/2017 Document, Report, or Work plan Review - other September 20-23, 2016 groundwater monitoring event. Groundwater samples were collected from the 4 site monitoring wells. Depth of water was 4.15 to 7.75 feet below top of well casing, the well casings are above the ground. Depth to groundwater below ground surface was not calculated. Up to 7.2 ug/l benzene, 0.41 mg/l DRO, 0.37 mg/l RRO, and 4.4 ug/l chromium in the 4 groundwater samples collected. The samples for TEX, GRO, PAHs, nickel, and other VOCs were non-detect. The monitoring well with the highest concentrations is monitoring well MWD which is located on the northwest corner. Groundwater flow direction was to the southwest this monitoring event. The monitoring wells were purged prior to sampling with a positive pressure hurricane pump. The report notes that the intake of the pump was within the top foot of the water column at the time of sampling, but this was not documented in the field notes. Monitoring well MWC volatile sample results may be biased low because the sample was collected using a bailer. Robert Weimer
2/2/2018 Document, Report, or Work plan Review - other Talked with DOT they will provide copy of the assessment report for the base and sidewall boring sampling. Robert Weimer
1/17/2019 Update or Other Action DEC sent another request for the submittal of the assessment report for the base and sidewall boring sampling. DOT has said that the work was conducted in 2015. Robert Weimer
9/16/2020 Document, Report, or Work plan Review - other On this date, ADEC received the Confirmation Sampling Report For West Dowling Road Reconstruction Phase II: C Street to Minnesota Drive submitted by Tellus and dated September 2020. This report discusses site work conducted during the West Dowling Construction Project, which was completed in 2015. This site work included soil excavations and stockpiling, soil samples collected from these stockpiles and from charcterizations borings and from excavations, and backfilling of all excavated soils within the project area at Lot 2. Soils samples collected from the excvations bottoms/sidewalls and borings from depths of 1.0 to 8.0 contained contaminant concentrations above cleanup levels with benzene up to 0.97 mg/kg, DRO up to 440 mg/kg, Chromium at 430 mg/kg , and nickel at 140 mg/kg (Note: only one sample (MWD) contained the chromium and nickel above cleanup levels from a sample collected at 5 to 7 feet bgs). Soil samples collected 10 to 14 feet bgs did not contain contaminant concentrations above cleanup levels. Grant Lidren
5/27/2021 Workplan Requested Sent work plan request letter to Nabors Alaska Drilling, Inc. Remaining contamination of concern on site to be included in the work plan, at a minimum, should include Diesel Range Organics (DRO), Benzene, Toluene, Ethylbenzene, Xylenes (BTEX), Chromium and Nickel for soils and Benzene, Toluene, Ethylbenzene, Xylenes (BTEX) for and Chromium and Nickel for groundwater. Jessica Hall
11/5/2021 Update or Other Action Sent PRP (Nabors Drilling Technologies USA, Inc.), ADEC Response to letter from Nabors Drilling Technologies USA, Inc. on September 16, 2021. Requested Work Plan be submitted. Jessica Hall
11/5/2021 Potentially Responsible Party/State Interest Letter Sent PRP (Raintree Properties LLC.) a work plan request letter via certified mail. Jessica Hall
12/3/2021 Workplan Requested Re-Sent PRP (Raintree Properties LLC.) a work plan request letter via email per request via phone call. Jessica Hall
6/17/2022 Document, Report, or Work plan Review - other ADEC sent comments to Leksand, LLC. for “Work Plan for Limited Site Investigation of Tract 2-B, Silverado Subdivision”, dated May 23, 2022. ADEC requested a revised work plan be submitted for review. Jessica Hall
8/2/2022 Site Characterization Workplan Approved ADEC sent Leksand LLC. an Approval letter for the “Work Plan for Limited Site Investigation of Tract 2-B, Silverado Subdivision”, dated July 25, 2022, with the req The work plan consists of installing three borings, two soil samples at the southeast and southwest border of tract 2-B for VOCs, DRO, Benzene, chromium, and nickle and one ground water sample for benzene on the southern border of tract 2-B. Existing Monitoring wells A&D will also be sampled and analyzed for benzene. Jessica Hall
10/20/2022 Document, Report, or Work plan Review - other ADEC sent the responsible party comments on “Limited Site Investigation of Tract 2-B, Silverado Subdivision”, dated October 10, 2022. ADEC requested a revised draft be submitted. Jessica Hall
10/31/2022 Site Characterization Report Approved Reviewed report for Limited Site Investigation of Tract 2-B, Silverado Subdivision. Site characterization activities included installation and sampling of three soil borings along the southern boundary of Tract 2-B, completion of one boring as a groundwater monitoring well and sampling of the new well and two existing wells, MW-A and MW-B on two separate occasions. Site Investigation also included an inspection of a former drum storage area for potential releases. Due to the high organic content of the peaty soil, the samples were analyzed both before and after silica gel cleanup. Post silica gel cleanup results indicate DRO was above the migration to groundwater cleanup level in samples from boreholes 2 and 3 in samples from 10 feet below ground surface. Benzene exceeded the cleanup level in samples from boreholes 1 and 2. Chromium and nickel were not detected above the cleanup level. Groundwater samples collected in August and September 2022 found only benzene above the cleanup level in the new well RSE-1, but below the cleanup level in wells MW-A and MD-D. Bill O'Connell
3/28/2023 Document, Report, or Work plan Review - other The four monitoring wells at the site were successfully decommissioned in accordance with DEC guidance. Bill O'Connell
3/28/2023 Institutional Control Update Covenant filed in support of site closure. Bill O'Connell
4/3/2023 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 79373 Dowling Road Extension . Bill O'Connell
4/11/2023 Cleanup Complete Determination Issued DEC has been determined that the benzene concentrations remaining in groundwater at the site do not pose an unacceptable risk to human health or the environment and no further remedial action will be required as long as the institutional controls are maintained and effective, and no information becomes available that indicates residual contamination poses an unacceptable risk. Please see Cleanup Complete with Institutional Controls Determination and Environmental Covenant attached to the database under the Documents tab. Bill O'Connell
4/11/2023 Institutional Control Record Established Institutional Controls established and entered into the database. Bill O'Connell

Contaminant Information

Name Level Description Media Comments
Benzene > Table C Groundwater

Control Type

Type Details
Environmental Covenant

Requirements

Description Details
Advance approval required to transport soil or groundwater off-site.
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)
Hazard ID Site Name File Number
1771 Pool Arctic Alaska - Silverado 2100.38.114

Missing Location Data

Because the GIS location data for this site has not been entered, we cannot direct you to its position on the map. Click "Continue" to proceed to the Contaminated Sites Web Map or "Close" to return to the site report.
Continue     Close

Public Notices  •  Regulations  •  Statutes
Press Releases  •  Contact

 

State of Alaska Department of Environmental Conservation

P.O. Box 111800
Juneau, AK 99811-1800
Phone: 907-465-5066
Fax: 907-465-5245
TDD: 800-770-8973
Physical Location: 410 Willoughby