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Site Report: ASD Nunaka Valley Elementary School


Site Name: ASD Nunaka Valley Elementary School
Address: 1905 Twining Drive, Anchorage, AK 99504
File Number: 2100.38.398
Hazard ID: 3001
Status: Cleanup Complete - Institutional Controls
Staff: IC Unit, 9074655229 dec.icunit@alaska.gov
Latitude: 61.203056
Longitude: -149.775833
Horizontal Datum:NAD83

We make every effort to ensure the data presented here is accurate based on the best available information currently on file with DEC. It is therefore subject to change as new information becomes available. We recommend contacting the assigned project staff prior to making decisions based on this information.

Problems/Comments

Petroleum contamination exceeding cleanup levels was discovered upon removal of a 500 gallon diesel and a 5,000 gallon Bunker "C" UST on June 22, 1998. Approximately 140 cubic yards of soil was stockpiled on site during the excavation. After analysis of the stockpiles 10 cubic yards of contaminated soil was taken to Alaska Soil Recycling for thermal remediation on July 1, 1998. The remainder was used as backfill on site. Piping to the tanks was removed to the extent possible and the remaining pipe was cut and capped at the exterior footing wall. Confirmation samples tested for RRO, GRO and BTEX from the 500 gallon UST's excavation pit did not exceeded the cleanup levels. DRO levels in two samples from this pit at 13 feet bgs were above the cleanup levels at 2,430 ppm and 2,790 ppm. No confirmation samples were taken from the 5,000 Buncker 'C' UST because field screening did not show any contaminates above ADEC cleanup levels. A passive bioventing system was installed to a depth of 13 feet bgs in the area of the 500 gallon diesel UST prior to backfilling, in June 1998. This system operated for an unknown amount time, the system was not functional in July of 2007. The contaminated soil remaining at 13 feet bgs was backfilled with the 'clean' stockpiled material and was covered by an addition to the building. No groundwater was encountered.

Action Information

Action Date Action Description DEC Staff
6/25/1998 Cleanup Plan Approved Approval by the CSP was granted to transport approximately 10 cubic yards of petroleum hydrocarbon contaminated soils to Alaska Soil Recycling for thermal treatment. Action added by Petrik. Eileen Olson
3/17/1999 Site Characterization Report Approved Reviewed a copy of the Shannon & Wilson, Inc. "UST Closure Assessment, Nunaka Valley Elementary School" dated August 1998. Sent a letter this date requesting a site characterization work plan to further define the horizontal and vertical extent of contamination - collect soil confirmation samples beneath the former 5,000 gallon UST location and submitted for lab analysis, sampling beneath the former location of feed and return lines, and collection of a ground water sample from beneath the former tanks location. Provide design and monitoring data to the CSP for the passive bioremediation treatment system installed during the June 22, 1998 field activities in the footprint of the 500 gallon UST without prior review or approval. Action added by Petrik. David Pikul
12/2/1999 Site Added to Database Two USTs were removed from the ground on 6/22/98 and petroleum contamination above cleanup levels was discovered. David Pikul
3/7/2000 Site Ranked Using the AHRM Initial site ranking. David Pikul
5/11/2004 Update or Other Action File number changed from CS68.09 to 2100.38.398. Sarah Cunningham
5/31/2007 Update or Other Action Staff assignment changed from Pikul to Petrik. Shannon Oelkers
5/19/2008 Exposure Tracking Model Ranking Initial ranking with ETM completed. Bill Petrik
7/16/2008 GIS Position Updated Used Google Maps in conjunction with Site Plan figure to update the latitude and longitude of the tanks site. Used the centroid of the two adjacent tanks as the target. Bill Petrik
7/18/2008 Update or Other Action As of 7/18/08 after review, the contents of the file are the following; -Shannon & Wilson, Inc. (S&W) letter report Request to Transport and Treat Hydrocarbon-Contaminated Soils from dated June 25, 1998. An approval letter was sent to S&W by Ms. Olson dated June 25, 1998. - S&W Report titled UST Closure Assessment, Nunaka Valley Elementary School, 1905 Twining Drive, Anchorage, Alaska dated August 1998. -A letter from Mr. Pikul dated March 17, 1999 responded to the S&W Report titled UST Closure Assessment, Nunaka Valley Elementary School, 1905 Twining Drive, Anchorage, Alaska dated August 1998. The letter requested: -a copy of the consultant’s field notes recorded during the UST closure and the Chain of Custody forms for the laboratory submitted soil samples. -a work plan developed that will characterize the vertical and horizontal extent of the petroleum hydrocarbon contamination at the site including confirmation sampling of those areas excavated during the tank removal operation. -the site investigation should include the collection of a groundwater sample from beneath the area of contamination to characterize site groundwater. -provide design and monitoring data to the CSP in order to evaluate the effectiveness of the system’s performance -An R&M UST Activity Summary dated August 9, 2007, recommending No Further Action at the site. ADEC requested any potential additional information from Edie Knapp of the ASD. Sydney Devine
9/29/2008 Update or Other Action In the report dated August 1998 Shannon & Wilson (S&W) discusses the removal of one 500 gallon Diesel UST and one 5,000 gallon Bunker ‘C’ UST on June 22, 1998. Lab results reported DRO levels as high as 2,790 ppm (the only analyte above ADEC clean-up criteria). 10 cubic yards of contaminated soil was taken to Alaska Soils Recycling for thermal treatment on July 1, 1998. ADEC approved this transport & remediation June 25, 1998. S&W’s report also mentions a passive bioventing remediation system that was installed June 22, 1998 (see figure 4). (No approval from ADEC found). The R & M Consultants, Inc. (R&M) letter dated August 9, 2007 refers to the passive bioventing system: “The system included a perforated pipe bedded in gravel at a depth of about 13 feet below ground surface, which was attached to a riser, extending to a wind-powered turbine on the roof. In July 2007, the riser was still visible attached to the building wall, but the turbine was gone.” The same R&M letter states that all housing in ¼ mile of the site was constructed after 1970 and is served by the public water system R&M says: “It is very unlikely that any active water wells are located within ¼ of the site.” In the conclusions and recommendations section of the R&M letter it states: “Excavation of these (remaining) contaminated soils would not be possible, because the area is now under a building.” R&M recommends no further action. Pam Clemens
9/30/2008 Meeting or Teleconference Held Meeting with Edie Knapp with ASD, Aaron Banks with R&M and ADEC staff Bill O'Connell and Pam Clemens to discuss open ASD sites Pam Clemens
10/22/2008 Update or Other Action Sent out letter to Edie Knapp with ASD concerning this site. File will be reviewed for possible closure. Pam Clemens
3/4/2009 Update or Other Action Sent email to Edie Knapp and Aaron Banks requesting soil gas evaluation prior to decommissioning the passive bioventing system at ASD Nunaka Valley Elementary. Pam Clemens
3/27/2009 Report or Workplan Review - Other Received letter report from R&M Consultants, Inc. on the VOC screening done March 26, 2009 at ASD Nunaka Valley Elementary School. No VOCs were detected. When the closure letter is drafted for this site a condition of closure will be the decommissioning of the remaining stand pipe for the passive bioventing system. The groundwater has not been investigated as per the 1999 request from David Pikul. Pam Clemens
5/19/2010 Exposure Tracking Model Ranking Initial ranking with ETM completed for source area id: 73976 name: 500 Gal. Diesel UST & 5,000 Gal. Bunker "C" UST Pam Clemens
5/21/2010 Exposure Tracking Model Ranking A new updated ranking with ETM has been completed for source area 73976 500 Gal. Diesel UST & 5,000 Gal. Bunker "C" UST. Pam Clemens
6/1/2010 Report or Workplan Review - Other Reviewed and approved final report of the standpipe decommissioning completed at Nunaka Valley Elementary School May 27, 2010. Pam Clemens
6/3/2010 Cleanup Complete Determination Issued Based on information provided to date, it has been determined that the contaminant concentrations remaining on site do not pose an unacceptable risk to human health or the environment, and this site will be closed with institutional controls. Pam Clemens
6/3/2010 Institutional Control Record Established Institutional Controls established and entered into the database. Pam Clemens
6/17/2010 Update or Other Action Received the signed Attachment A: Cleanup complete-ICs Agreement and Signature Page. See attachments. Pam Clemens
2/16/2012 Update or Other Action Staff changed from Pam Clemens to IC Unit. Kristin Brown
11/9/2012 Institutional Control Compliance Review IC review conducted. Reminder system set-up to contact responsible party in 2015. Kristin Brown
6/22/2015 Institutional Control Update An IC reminder letter was issued to the responsible party on this date. Kristin Brown

Contaminant Information

Name Level Description Media Comments
DRO Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation Soil DRO remaining under the building addition is not available to receptors. If the building is removed the subsurface soil must be investigated to determine the levels of DRO at that time.

Control Type

Type Details
Signed CS Determination

Requirements

Description Details
Advance approval required to transport soil or groundwater off-site.
Excavation / Soil Movement Restrictions
When Contaminated Soil is Accessible, Remediation Should Occur

Missing Location Data

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