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Site Report: ADOT&PF Former Napa Auto Car Care Center

Site Name: ADOT&PF Former Napa Auto Car Care Center
Address: 211 Bragaw Street, Glenn and Bragaw Interchange, Anchorage, AK 99501
File Number: 2100.38.490
Hazard ID: 4490
Status: Cleanup Complete - Institutional Controls
Staff: IC Unit, 9074655229
Latitude: 61.222000
Longitude: -149.807700
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.


Soil contaminated with tetrachloroethene, diesel range organics, and residual range organics was discovered following the removal of the foundation of the former Napa Auto Car Care Center. The contaminated soil was excavated and stockpiled until groundwater was reached. The environmental contractor, CEI, was not able to excavate and treat the smear zone. Following a series of meeting with multiple affiliated parties, ADOT&PF decided to backfill the excavation with the contaminated soil and evaluate any present and future groundwater impacts over time.

Action Information

Action Date Action Description DEC Staff
11/1/2007 Site Added to Database Site added to the database. Mitzi Read
11/2/2007 Exposure Tracking Model Ranking Intitial Ranking Complete for Source Area: 75477 (Autogenerated Action)
1/17/2008 Exposure Tracking Model Ranking Updated Ranking Complete for Source Area: 75477 (Autogenerated Action)
1/25/2008 Update or Other Action DEC staff reviewed a report titled "Characterization Report of Former Off-site Temporary Contaminated Soils Stockpile Location." The report summarized the characterization of areas beneath the temporary soil stockpile and the adjacent areas in the central environmental Inc. yard. The purpose of the characterization is to document that all contaminated soils temporarily stockpiled according to a DEC approved work plan dated 8/20/07, at the CEI facility had been removed from the site. DRO and TCE were not detected in soil samples and the stockpiled soil was placed on a liner. Todd Blessing
1/25/2008 Update or Other Action DEC staff issued a letter to Brian Shumacher, Project Coordinator for the Alaska Department of Transportation and Public Facilities. DEC requested that Mr. Shumacher hire a qualified third party to issue a site investigation work plan to DEC by March 28, 2008. The work plan should define the means and methods to sample and analyze groundwater for contaminants of concern and develop a conceptual site model. Todd Blessing
4/11/2008 Update or Other Action DEC staff reviewed a work plan dated March 28, 2008 that was prepared by EMI, Inc. EMI proposed to sample and install three monitor wells. One of the monitor wells (MW1) will be located within the footprint of the former excavation pit and the other two downgradient from the excavation pit. Soil samples will be collected from soil boring MW1and it will be advanced to a depth of 60 feet below ground surface. In a letter dated April 11, 2008, DEC approved of the work plan. Todd Blessing
6/3/2008 Update or Other Action DEC staff received a phone call from Brian Shumacher, Engineering Assistant #3 with the ADOT&PF on June 02, 2008. Brian informed DEC that on May 31, 2008, two Wilder employees were exposed to an unknown chemical south of the Glenn Highway in an excavation trench. The employees were subsequently taken to the hospital (Alaska Regional) for diagnostic tests and treatment. DEC recommended that ADOT&PF call the National Guard's 103rd Civil Support Team (CST) to assess if the site is safe for continued work. On June 2nd, the 103rd CST completed their investigation and concluded that the excavation trench is safe to work as long as soil is not disturbed. The hazardous chemical is believed to be isopropyl alcohol. On June 3, 2008 DEC staff approved of an interim work plan proposed by EMI to excavate in the contaminated area to safely install a storm drain. Suspected contaminated soils will be placed on the west side of the trench while non-suspect soils will be placed on the east side of the trench. The soil will be placed directly on the existing asphalt. The suspect stockpile will be covered to prevent rain and wind erosion until further analysis is completed. The excavation workers will wear Level C protective equipment. Todd Blessing
5/27/2009 Site Characterization Report Approved DEC staff reviewed Environmental Management Inc.’s (EMI's) “Monitoring Well Installation and Sampling Report, Glenn and Bragaw Interchange”, Dated April 2009. In this report, EMI documented the sampling of soil and groundwater from August through December 2008. Three groundwater monitoring wells (MW-1 through MW-3) were installed and sampled. Additionally, four soil samples were collected from the borehole of MW-1. In soil samples, tetrachloroethylene (PCE) values ranged from nondetect to 49.5 µg/kg, while in groundwater samples, PCE values ranged from 2.08 to 4.73 µg/L. The levels of PCE detected in groundwater samples were less than CSP’s groundwater cleanup level (i.e.5 µg/L). However, the relative percent difference between a primary and duplicate groundwater sample was 68% which suggests that accuracy and/or precision of the groundwater monitoring results are questionable. Consequently, CSP issued a letter on May 27th requesting that ADOT&PF conduct two additional groundwater monitoring events to evaluate long term trends in dissolved PCE concentrations. Todd Blessing
8/25/2009 Long Term Monitoring Established DEC staff reviewed and approved Environmental Management Inc.’s (EMI's) “Long Term Groundwater Monitoring Plan”, dated August, 2009. Groundwater samples will be collected from monitoring wells MW-1, MW-2, and MW-3 twice a year (in summer and winter) to be analyzed for volatile organic compounds by EPA method 8260B. In monitoring well MW-1, groundwater will be sampled from the upper and lower aquifer. After two additional sampling events, the analytical data will be evaluated to determine future groundwater monitoring events. Todd Blessing
12/16/2009 Site Characterization Report Approved DEC staff reviewed EMI Inc.'s "Summer 2009 Groundwater Sampling Report". Three monitoring wells designated MW-1 through MW-3 were sampled for volatile organic compounds during September 2009. Groundwater was found at roughly 6 to 8 feet below ground surface and groundwater flow direction was south westerly. The levels of PCE in groundwater ranged from 2.37 to 5.18 ug/L. Todd Blessing
3/1/2010 Update or Other Action DEC staff reviewed EMI's "Groundwater Sampling Summary Report", dated February 10, 2010. EMI personnel collected groundwater samples from wells MW-1 through MW-3. PCE was detected in all three wells and the groundwater flow direction was determined to be southwest. The levels of PCE in wells MW-2 and MW-3 slightly exceeded 18 AAC 75.345 Table C values. PCE levels ranged from 0.0022 to 0.0052 mg/L. Todd Blessing
10/24/2011 Update or Other Action DEC issued a notice to proceed to Shannon and Wilson to continue groundwater monitoring under Environmental Management Inc.’s (EMI's) “Long Term Groundwater Monitoring Plan”, dated August, 2009. Shannon and Wilson will conduct two monitoring events during 2012. Todd Blessing
3/22/2012 Update or Other Action Exposure tracking model ranking updated. Todd Blessing
7/19/2012 Update or Other Action Staff reviewed Shannon and Wilson's groundwater monitoring report. Two groundwater monitoring events were conducted in 2012. Groundwater samples were collected from each well (MW-1 through MW-3) and analyzed for VOCs by ADEC approved methods. In these groundwater samples, PCE was the only contaminant of concern detected and the levels of PCE ranged from 1.76 to 4.20 µg/L. Todd Blessing
8/3/2012 Cleanup Complete Determination Issued PCE and DRO contamination above established default cleanup levels in soil remains on-site at 1 to 15 feet below ground surface as depicted in Figure 1. ADEC has determined there is no unacceptable risk to human health or the environment since site exposure pathways that are complete have been determined to be de minimis. Therefore, this site will be issued a Cleanup Complete- ICs determination subject to the following. 1. Any future change in land use may impact the exposure assumptions cited in this document. If land use, tenant and/or ownership changes, current ICs may not be protective and ADEC may require additional remediation and/or ICs. Therefore, ADOT&PF shall notify ADEC if ADOT&PF becomes aware of any change in land ownership and/or use, if earlier. The report can be sent to the local ADEC office or electronically to For example, if any buildings are proposed to be constructed or demolished within 100 feet of the known remaining soil Contamination as shown on Figure 1, ADOT&PF must notify ADEC prior to construction to allow ADEC to review the plans and perhaps modify the ICs because the vapor intrusion risk that is now considered pathway incomplete due to current land use may show a potential exposure risk. 2. Any proposal to transport soil or groundwater off site requires ADEC approval in accordance with 18 AAC 75.325 (i). A “site” [as defined by 18 AAC 75.990 (115)] means an area that is contaminated, including areas contaminated by the migration of hazardous substances from a source area, regardless of property ownership. (See attached site figure.) (See Note 19.) 3. Movement or use of contaminated material in a manner that results in a violation of 18 AAC 70 water quality standards is prohibited. Todd Blessing
8/3/2012 Institutional Control Record Established Institutional Controls established and entered into the database. Todd Blessing
8/30/2012 Institutional Control Compliance Review IC Compliance Review conducted and Staff changed from Todd Blessing to IC Unit. Reminder system set-up to follow-up with responsible party in 2017. Kristin Thompson
5/16/2013 Long Term Monitoring Complete Administrative action added during a quality control check. Kristin Thompson
8/9/2017 Institutional Control Compliance Review IC compliance review conducted. Closure/IC Details updated. ICs Verification letter issued with a request for the ICs Agreement Page be signed and returned. Reminder system set to follow-up on the ICs agreement in one month, and every three years for periodic review. Kristin Thompson
8/23/2017 Institutional Control Periodic Reporting Received the signed ICs Agreement page this date. Kristin Thompson

Contaminant Information

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

Control Type

Type Details
Signed CS Determination


Description Details
Advance approval required to transport soil or groundwater off-site. Standard condition.
Groundwater Use Restrictions Installation of groundwater or drinking water wells at this site will require approval from ADEC.
Periodic Review Every three years.
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.

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