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Site Report: ARRC M-I Swaco Lease Property

Site Name: ARRC M-I Swaco Lease Property
Address: 721 West 1st Avenue, Anchorage, AK 99501
File Number: 2100.38.556
Hazard ID: 26426
Status: Cleanup Complete - Institutional Controls
Staff: Grant Lidren, 9072698685
Latitude: 61.221468
Longitude: -149.898867
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.


In 2015, diesel range organic (DRO) contamination was encountered at three areas on the property during an environmental assessment. The contaminated area to the east of the property is reportedly the location of a former above ground storage tank (AST). The source for the other two areas is unknown. The property was constructed by M-I in 1978 and has served as a district office and dry product storage facility since opening. The current leaseholder Schlumberger has recently discontinued using this property for storage.

Action Information

Action Date Action Description DEC Staff
3/15/2002 Report or Workplan Review - Other Historic work was conducted at this site in the early 2000s. ADEC received the Remedial Activities Report Former AST Location M-I Facility 721 West 1st Avenue dated March 2002 submitted by ENSR. Contamination was initially encountered at the former AST area during an August 2000 Baseline Assessment. In 2001, 13 cubic yards of contaminated soil was excavated and treated at ASR leaving an excavation 9 feet long, 6 feet wide, and 5.5 to 6.5 feet bgs. Four confirmation samples collected and analyzed for DRO/RRO contained detectable concentrations below method two petroleum hydrocarbon soil cleanup levels. The excavation was back filled with clean fill. This historic spill event known as “721 W. 1st AVE MI DRILLING Spill #: 01239919901” was managed and closed by ADEC spill response (PERP). * Not Assigned
7/24/2015 Site Characterization Report Approved On this date, ADEC received the Environmental Site Assessment Report at M-I Swaco Lease Property, 721 West 1st Avenue submitted by SLR and dated July 2015. The investigation was two part. The first investigation was conducted in April 2015 and consisted of advancing of 17 soil borings and the collected of eight subsurface samples. The second investigation was conducted in June 2015 and consisted of stepping out from contaminated areas identified in April 2015. 18 step-out borings were advanced at 10 foot intervals and eight soil samples were collected. Borings for both the June and April investigations were advanced 10 feet bgs and saturated soil was encountered 5 to 8 feet bgs. Based off these investigations, three areas of DRO contamination were identified at boreholes: MI-BH-11, MI-BH-17 (area of former AST), and MI-BH-33. Soil samples collected from bore hole MI-BH-11 - 6 to 6.5 feet bgs at the groundwater interface - contained DRO at 473 mg/kg; surface samples were ND. Soil samples collected from bore hole MI-BH-17 – 5 to 7.5 feet bgs at the groundwater interface - contained DRO at 1,270 mg/kg; surface samples were ND. Surface soil samples collected from bore hole MI-BH-33 – 1 to 2 feet bgs- contained DRO up to 3,700 mg/kg DRO; subsurface analytical soil samples were not collected from this location Grant Lidren
8/4/2015 Site Added to Database A new site has been added to the database Mitzi Read
8/4/2015 Exposure Tracking Model Ranking Initial ranking with ETM completed for source area id: 79797 name: Property-Wide Diesel Range Organics Contamination Mitzi Read
8/17/2015 Potentially Responsible Party/State Interest Letter On this date, ADEC sent a PRP letter to Schlumberger Alaska. Grant Lidren
9/16/2015 Site Characterization Workplan Approved The Alaska Department of Environmental Conservation (ADEC) Contaminated Sites Program (CSP) has received and reviewed the Soil Removal Work Plan at M-I Swaco Lease Property 721 West 1st Avenue Anchorage, Alaska submitted by SLR and dated August 2015. On September 15, 2015, ADEC received the response to review comments from SLR. Based off the work plan and SLR response to comments, ADEC has no objections to the work plan and SLR may proceed. Grant Lidren
9/24/2015 Site Visit Conducted site visit with SLR on this date. Two soil borings were advanced and completed as monitoring well via direct push. ADEC Field Inspection Checklist completed. Grant Lidren
11/12/2015 Site Characterization Report Approved On this date, ADEC received the Soil Removal Report M-I Swaco Lease Property submitted by SLR and dated November 2015. Site activities including excavating soil from two areas and advancing two monitoring wells. Soil and groundwater samples collected at the two monitoring well borings did not contain contaminant concentrations above clean up levels. The two excavated areas included the east excavation at historic boring MI-BH-17 and the south excavation at historic boring MI-BH-08. At the east excavation 32 cubic yards of soil were removed to a depth of 2 to 5.5 feet bgs. This excavation was limited by a utility pole and a paved parking area. At the south excavation, 64 cubic yards of soil were removed to the groundwater interface at a depth of 2.5 feet bgs. The excavation was limited by a fence to the south and phone and sewer line to the north. Eleven confirmation soil samples were collected from the floor and sidewall from the east excavation, but only from the sidewalls of the south excavation due to standing water. Three out of six soil samples collected from the south excavation contained DRO above cleanup levels up to 3,250 mg/kg. Two out of five soil samples collected from the east excavation contained DRO up to 3,940 mg/kg. Both of these samples were collected adjacent to the utility pole. The excavations were backfilled with clean fill. Grant Lidren
12/18/2015 Report or Workplan Review - Other On this date, ADEC received the Well Decommissioning Work Plan, M-I Swaco Lease Property, 712 West 1st Ave submitted by SLR. On December 15, 2015, monitoring wells MW-1 and MW-2 were decommissioned in accordance with DEC guidance. Grant Lidren
1/5/2016 Cleanup Complete Determination Issued The Alaska Department of Environmental Conservation (ADEC) Contaminated Sites Program (CSP) has reviewed the environmental records for the ARRC M-I Swaco Lease Property. Based on the information provided to date and the administrative record, the ADEC has determined that the contaminant concentrations remaining on site do not pose an unacceptable risk to human health or the environment. No further remedial action will be required as long as the site is in compliance with institutional controls. Grant Lidren
1/5/2016 Institutional Control Record Established Institutional Controls established and entered into the database. Grant Lidren
1/27/2016 Update or Other Action On this date, ADEC received signed CC-IC agreements from ARRC and M-I LLC. Grant Lidren
4/20/2016 Offsite Soil or Groundwater Disposal Approved On this date, ADEC received the soil treatment letter from ASR. A total of 143.07 tons of petroleum contaminated soil was received and will be remediated in accordance with ASR's State approved facility operations plan. Grant Lidren

Contaminant Information

Name Level Description Media Comments
DRO 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.
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)
Groundwater Use Restrictions

Missing Location Data

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