Site Report: GSA Anchorage Federal Building UST #1

Site Name:	GSA Anchorage Federal Building UST #1
Address:	222 West 7th Avenue, Anchorage, AK 99513
File Number:	2100.26.613
Hazard ID:	26839
Status:	Cleanup Complete
Staff:	No Longer Assigned, 9074655229 dec.icunit@alaska.gov
Latitude:	61.215469
Longitude:	-149.885130
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.

Site Chronology
IC / Closure Details
Documents
Associated Sites

Problems/Comments

One regulated 8,000 gallon underground storage tank (UST #1) and associated piping, was removed from the subject property between July 10 and August 31, 2017. Prior to tank closure approximately 1,000 gallons of diesel fuel were pumped out of the tank, and no holes were observed in the tank. Two separate excavations were advanced to remove the tank and associated piping. The tank was originally tied to a concrete ballast with metal straps. This ballast was left in place. Groundwater was not encountered during the UST removal. Approximately 250 cubic yards of soil were generated during removal and separated into potentially clean and potentially-impacted piles, based on field screening. Following analytical sampling 130 cubic yards of impacted soil were taken to ASR for treatment. Eight analytical soil samples were collected from the UST excavation and two additional samples were collected from the piping excavation. The southwest side of the excavation could not be sampled due to safety concerns and the excavation base could not be sampled due to the presence of the ballast. Soil samples contained up to 9,400 mg/kg diesel range organics, 0.123 mg/kg benzene, 12.3 mg/kg toluene, 27.9 mg/kg ethylbenzene, and 143 mg/kg xylenes.

Action Information

Action Date	Action	Description	DEC Staff
3/1/2018	Site Added to Database	A new site has been added to the database	Mitzi Read
3/1/2018	Leaking Underground Storage Tank Release Confirmed - Petroleum	LUST site created in CSP database for source area 8,000-Gallon Diesel UST #1, 80200	Mitzi Read
6/22/2018	Potentially Responsible Party/State Interest Letter	Potentially Responsible Party Letter Sent.	Chelsy Passmore
7/10/2018	Site Characterization Workplan Approved	The Alaska Department of Environmental Conservation (ADEC) has reviewed the “Work Plan to Conduct Release Investigation Activities” for the GSA Anchorage Federal Building UST #1 site located at 222 West 7th Ave in Anchorage, Alaska. The workplan details the work to be done at the site during the summer of 2018 which includes removing and investigating the remote fill pipe, and conducting a soil and groundwater investigation. ADEC has no objections to the work plan.	Chelsy Passmore
7/19/2019	Document, Report, or Work plan Review - other	The ADEC reviewed the "Release Investigation Activities" report, dated January 2019, for the property at 222 W 7th Ave, and has no objections. Work at the site consisted of removing and investigating a remote fill pipe, and advancing 3 soil borings which were completed as monitoring wells. An estimated 58 feet of piping was excavated and removed from approximately 4.6 feet below ground surface. The piping began at the former UST running approximately 38 ft east then turning 90 degrees and continuing 20 feet north. Four analytical soil samples (two from the excavation and two from the subsequent stockpile) were collected. In addition 2 analytical soil samples were collected from each of the 3 soil borings, and once completed as monitoring wells 4 groundwater samples were collected. Soil contained diesel range organics (DRO) up to 522mg/kg in the piping excavation and up to 284mg/kg in the stockpile. No soil from the boring contained contaminant concentrations above ADEC cleanup levels. Groundwater samples did not contain contaminant concentrations above ADEC cleanup levels.	Chelsy Passmore
8/6/2019	Document, Report, or Work plan Review - other	Quarterly groundwater monitoring report dated 7/11/2019 was submitted. Groundwater was sampled in August and November of 2018 and February and May of 2019. DRO, chloromethane, and dichlorofluoromethane were detected but did not exceed cleanup levels.	Janice Wiegers
9/30/2019	Leaking Underground Storage Tank Cleanup Initiated - Petroleum	Action addition for grant reporting purposes.	Evonne Reese
9/15/2020	Update or Other Action	DEC reviewed the file and quarterly groundwater monitoring results. Additional information needed, including a Conceptual Site Model, cumulative risk evaluation, and vapor intrusion evaluation. Monitoring wells also need to be removed prior to site closure. Letter describing this review was sent to the GSA.	Janice Wiegers
12/18/2020	Document, Report, or Work plan Review - other	Shannon & Wilson submitted a CSM report.	Janice Wiegers
7/15/2021	Exposure Tracking Model Ranking	Initial ranking with ETM completed for source area id: 80200 name: 8,000-Gallon Diesel UST #1	Brandi Tolsma
9/22/2021	Document, Report, or Work plan Review - other	Receive and approved work plan to decommission monitoring wells.	Janice Wiegers
10/5/2021	Document, Report, or Work plan Review - other	On this date, ADEC received report for well decommissioning activities at 222 West 7th Ave. Groundwater monitoring wells MW1, MW2, and MW3 have been removed in accordance with ADEC's September 2013 Monitoring Well Guidance document.	Brandi Tolsma
10/26/2021	Cleanup Complete Determination Issued	On this date, ADEC Cleanup Complete determination was issued. ADEC found that soil was below ingestion and human health cleanup levels under 18 AAC 75.341 Method 2 Tables B1 and B2, and below cleanup levels for groundwater under 18 AAC 75.345, Table C.	Brandi Tolsma

Action Date

Action

Description

DEC Staff

3/1/2018

Site Added to Database

A new site has been added to the database

Mitzi Read

3/1/2018

Leaking Underground Storage Tank Release Confirmed - Petroleum

LUST site created in CSP database for source area 8,000-Gallon Diesel UST #1, 80200

Mitzi Read

6/22/2018

Potentially Responsible Party/State Interest Letter

Potentially Responsible Party Letter Sent.

Chelsy Passmore

7/10/2018

Site Characterization Workplan Approved

The Alaska Department of Environmental Conservation (ADEC) has reviewed the “Work Plan to Conduct Release Investigation Activities” for the GSA Anchorage Federal Building UST #1 site located at 222 West 7th Ave in Anchorage, Alaska. The workplan details the work to be done at the site during the summer of 2018 which includes removing and investigating the remote fill pipe, and conducting a soil and groundwater investigation. ADEC has no objections to the work plan.

Chelsy Passmore

7/19/2019

Document, Report, or Work plan Review - other

The ADEC reviewed the "Release Investigation Activities" report, dated January 2019, for the property at 222 W 7th Ave, and has no objections. Work at the site consisted of removing and investigating a remote fill pipe, and advancing 3 soil borings which were completed as monitoring wells. An estimated 58 feet of piping was excavated and removed from approximately 4.6 feet below ground surface. The piping began at the former UST running approximately 38 ft east then turning 90 degrees and continuing 20 feet north. Four analytical soil samples (two from the excavation and two from the subsequent stockpile) were collected. In addition 2 analytical soil samples were collected from each of the 3 soil borings, and once completed as monitoring wells 4 groundwater samples were collected. Soil contained diesel range organics (DRO) up to 522mg/kg in the piping excavation and up to 284mg/kg in the stockpile. No soil from the boring contained contaminant concentrations above ADEC cleanup levels. Groundwater samples did not contain contaminant concentrations above ADEC cleanup levels.

Chelsy Passmore

8/6/2019

Document, Report, or Work plan Review - other

Quarterly groundwater monitoring report dated 7/11/2019 was submitted. Groundwater was sampled in August and November of 2018 and February and May of 2019. DRO, chloromethane, and dichlorofluoromethane were detected but did not exceed cleanup levels.

Janice Wiegers

9/30/2019

Leaking Underground Storage Tank Cleanup Initiated - Petroleum

Action addition for grant reporting purposes.

Evonne Reese

9/15/2020

Update or Other Action

DEC reviewed the file and quarterly groundwater monitoring results. Additional information needed, including a Conceptual Site Model, cumulative risk evaluation, and vapor intrusion evaluation. Monitoring wells also need to be removed prior to site closure. Letter describing this review was sent to the GSA.

Janice Wiegers

12/18/2020

Document, Report, or Work plan Review - other

Shannon & Wilson submitted a CSM report.

Janice Wiegers

7/15/2021

Exposure Tracking Model Ranking

Initial ranking with ETM completed for source area id: 80200 name: 8,000-Gallon Diesel UST #1

Brandi Tolsma

9/22/2021

Document, Report, or Work plan Review - other

Receive and approved work plan to decommission monitoring wells.

Janice Wiegers

10/5/2021

Document, Report, or Work plan Review - other

On this date, ADEC received report for well decommissioning activities at 222 West 7th Ave. Groundwater monitoring wells MW1, MW2, and MW3 have been removed in accordance with ADEC's September 2013 Monitoring Well Guidance document.

Brandi Tolsma

10/26/2021

Cleanup Complete Determination Issued

On this date, ADEC Cleanup Complete determination was issued. ADEC found that soil was below ingestion and human health cleanup levels under 18 AAC 75.341 Method 2 Tables B1 and B2, and below cleanup levels for groundwater under 18 AAC 75.345, Table C.

Brandi Tolsma

Contaminant Information

Name	Level Description	Media	Comments
1,2,4-Trimethylbenzene	Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation	Soil	1,2,4-Trimethylbenzene reported at 16.9 mg/kg at 8.5-9ft bgs on 8/31/2017.
1,3,5-Trimethylbenzene	Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation	Soil	1,3,5-Trimethylbenzene reported at 5.99 mg/kg at 8.5-9ft bgs on 8/31/2017.
1-Methylnaphthalene	Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation	Soil	1-Methylnaphthalene reported at 1.45 mg/kg at 8.5-9ft bgs on 8/31/2017.
2-Methylnaphthalene	Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation	Soil	2-Methylnaphthalene reported at 2.5 mg/kg at 8.5-9ft bgs on 8/31/2017.
BTEX	Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation	Soil	Benzene reported at 0.00565 mg/kg at 25-30ft bgs on 8/21/2018. Ethylbenzene reported at 1.61 mg/kg at 8.5-9ft bgs on 8/31/2017. Xylenes reported at 13.6mg/kg at 8.5-9ft bgs on 8/31/2017.
DRO	Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation	Soil	DRO reported at 3730 mg/kg at 8.5-9ft bgs on 8/31/2017.
GRO	Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation	Soil	GRO reported at 417 mg/kg at 8-9.5ft bgs on 8/31/2017.
Naphthalene	Between Method 2 Migration to Groundwater and Human Health/Ingestion/Inhalation	Soil	Naphthalene reported at 1.01 mg/kg at 8.5-9ft bgs on 8/31/2017.

Name

Level Description

Media

Comments

1,2,4-Trimethylbenzene