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PUBLIC NOTICE | Proposed Leaking UST Case Closure for Case File 5158.01-.03

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

LUST Case File No.: 5158.01-.03

Facility ID No.: 0-003721
Navajo County

Facility address: 
Phillips 66 Company No. 014880
405 Navajo Boulevard
Holbrook, AZ 86025


According to the LUST file, a UST system was installed in approximately 1968. The UST owner/operator was the Phillips Petroleum Company (Phillips 66). In January 2000, Phillips 66 removed one 550-gallon waste oil UST and abandoned in place two 6,000-gallon gasoline USTs. Soil samples collected during the permanent closure activities indicated a release of petroleum hydrocarbons had occurred. ADEQ assigned LUST release 5158. 01 to the waste oil UST, LUST release 5158.02 to the former dispenser islands, and LUST release 5158.03 to the gasoline USTs. The permanent closure and site characterization activities were conducted by SECOR International Inc. (SECOR) on behalf of Phillips 66. SECOR installed groundwater monitoring wells in March 2000. In 2000, Tierra Dynamics Inc. (TDI) installed numerous monitoring wells in this area of Holbrook for various LUST sites. SECOR submitted a Site Characterization Report to ADEQ and recommended completion of a Corrective Action Plan (CAP) requesting no further action be taken to address soil contamination with benzene at a concentration exceeding the residential Soil Remediation Level (rSRL). SECOR also proposed using monitored natural attenuation to address dissolved phase contaminants of concern (CoCs) at concentrations that exceeded their applicable Aquifer Water Quality Standards (AWQS). In June 2000, ADEQ stated that the CAP was not needed but soil and groundwater remediation was necessary. Site Characterization was approved in January 2000. Active soil and groundwater remediation using multiphase extraction (MPE) occurred between October 2009 and October 2014. The system was restarted in June 2015 and operated until March 2018.

A site specific risk assessment and detailed file/information search were also completed. On-site groundwater data shows volatile organic compound (VOC) contamination present over applicable AWQS. The remaining CoC contamination in groundwater is 1, 2-dichloroethane (1, 2-DCA) which was found in leaded gasoline. On-site soil confirmation borings collected at each of the three LUST release locations show no CoCs at concentrations that exceed (rSRLs) or minimum Groundwater Protection Levels (GPLs). Soil samples were analyzed for all petroleum related CoCs which include VOCs, polyaromatic hydrocarbons (PAHs) and tetraethyl lead (which is found in leaded gasoline) given the operational dates of the UST system. The groundwater flow direction has been historically west. The depth to water in March 2018 was 14 feet below ground surface (bgs).

Based upon the results of remedial activities and site specific information, the above-referenced LUST site is eligible for alternative LUST closure under Arizona Revised Statutes (A.R.S.) §49-1005(E). Arizona Administrative Code (A.A.C.) R18-12-263.04 allows case closure of a LUST site with groundwater contamination above the AWQS or Tier 1 Standards.

Review Document 

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

Public Comment Period 

Dates: July 17, 2018  August 17, 2018

Comments may be submitted as follows:
     By Email | Send Email > 
     By Mail (Must be postmarked or received by August 17, 2018):

       Debi Goodwin
       Waste Programs Division
       1110 W. Washington Street
       Phoenix, AZ  85007 

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