PUBLIC NOTICE | Proposed Leaking UST Case Closure for Case File 3273.01-.03

ADEQ is considering closure of the following leaking underground storage tank (LUST) case:

LUST Case File No.: 3273.01-.03     

Facility ID No.: 0-005029
Pinal County

Facility address: 
Coolidge Thrift Store
1495 S. Arizona Blvd.
Coolidge, AZ 85228

Information

1495 South Arizona Boulevard in Coolidge is currently a vacant lot. The site was formerly a thrift store and also a retail gasoline service station. The USTs were installed in 1966 when leaded gasoline was being used. The entire system was removed in August 1998.  Following the installation of soil borings and sampling performed at the site in 1996, three LUST releases were assigned at the underground storage tank (UST) area and 2 dispenser locations. The corrective actions were conducted by the property owner.  The UST system was determined to be orphan by ADEQ in 1998.  Subsequent site investigation activities found that the contamination reached groundwater at 64 feet below ground surface (bgs) at that time. Several groundwater monitoring wells were installed at the site and off site to delineate groundwater contamination. In July, 2005, five (5) deeper groundwater monitoring wells were installed to 100 feet depth due to declining groundwater levels. Currently groundwater is around 77 feet bgs and has historically flowed northwest. The groundwater flows to the southwest based on February 2017 data, likely due to current agricultural well pumping.

ADEQ’s State Lead Unit on behalf of the property owner, started corrective actions in 2008. After initiating the corrective action during this year, the project temporarily stopped until the end of 2009 due to program funding issues. The remediation approach included air and ozone sparging and soil vapor extraction (SVE) for groundwater and soil clean up, respectively. These systems were connected to 9 groundwater sparging wells and 8 SVE wells. The system became operational in January 2010. A confirmatory soil sampling performed at the 3 release locations in May 2012 indicated that soil contamination is below cleanup standards. The residual contamination found was in the smear zone only. Subsequently, the SVE unit was decommissioned.  The sparge system continued operation until November 2015.  Most of the contaminants in groundwater have decreased as a result of remediation.  In June 2014, some of the monitoring wells were found to be dry including one in the higher contaminated area as a result of declining groundwater level. A deeper monitoring well was installed in this area in October 2014. Groundwater data has been collected since the first set of monitoring wells were installed in 2014. In order to accelerate groundwater remediation, Persulfox™ was injected in March 2014, February 2015 and September 2016 into the monitoring wells. Groundwater sampling results showed significant decrease of contamination as of February 2017.

Current data provided by Stantec, contractor to the State Lead Unit, and all other available site information has been used by ADEQ to determine whether remaining levels of contaminants at the site are adequately protective of human health and the environment.  A site specific risk assessment and detailed file/information search were also completed.  Volatile organic compound (VOC) analytical groundwater results in MW-12 show that 1, 2-dichloroethane (1,2-DCA) concentrations remain above the applicable Tier 1 Corrective Action Standard of 5.0 µg/L. 1,2-DCA and ethylene dibromide (1,2-DCA and EDB) were leaded gasoline additives. The results for all other monitoring wells show no contamination present and is available in the LUST file.

Review Document 

Review results of remedial activities and entire public notice | View/Print >

Public Comment Period 

Dates: June 7, 2017  July 7, 2017

Comments may be submitted as follows:
     By Email | Send Email > 
     By Mail (Must be postmarked or received by July 7, 2017):

       ADEQ
       Samar Bhuyan
       Waste Programs Division
       1110 W. Washington Street
       Phoenix, AZ  85007 

Documents may also be reviewed in person at the ADEQ Record Center | Learn More >