PUBLIC NOTICE | Proposed Leaking UST Case Closure for Case File 5399.01, .03
ADEQ is considering closure of the following leaking underground storage tank (LUST) case:
LUST Case File No.: 5399.01, .03
Facility ID No.: 0-004430
490 S. Gila Street
Yuma, AZ 85365
The former Sellers Petroleum facility is approximately 0.75 acres and is located at 490 S. Gila Street in Yuma. The property is within the zoned “Old Town” area with a Historic District overlay. The City of Yuma is developing a conceptual plan for a downtown university campus on more than 50 acres and is considering purchasing this parcel as part of that redevelopment project. The UST system was installed in approximately 1985. The UST owner/operator was Snakebite Leasing Inc. Subsurface investigation activities beginning in 2004 indicated that fuel releases from the east gasoline pump island (release number 5399.01) and the east diesel pump island (release number 5399.02) had occurred. Several soil borings and groundwater monitoring wells (MWs) were installed at the site during investigation of the releases. The .02 release was subsequently closed in March 2010 when the Site Characterization Report was approved. Soil samples were analyzed for volatile organic compounds (VOCs) and polyaromatic hydrocarbons (PAHs). No lead scavenger VOC compounds were reported in historic soil or groundwater samples collected. Four 10,000 gallon USTs, associated dispensers and piping were removed in March 2012 and release number 5399.03 was assigned. Historic soil data shows benzene, xylene and trimethylbenzenes were reported over applicable regulatory standards. Historic groundwater data shows benzene and methyl tert-butyl ether (MTBE). MTBE was used to oxygenate unleaded gasoline to reduce vehicle exhaust pollution, until approximately 2004. The contamination source and the remainder of the facility is currently unoccupied. The land use around the property is mixed industrial, light commercial, and residential.
Corrective actions included over excavation of contaminated soil and aeration of the excavation area and the use of nutrient enhancement of the groundwater in offsite monitoring well MW-6. Contamination in groundwater is limited to MTBE in MW-6. The groundwater flow direction historically has been to the west-northwest and the depth to groundwater is approximately 15 feet below ground surface (bgs) as of April 2017. Fill material consisting of sand or gravelly clay is present to a depth of 10 to 13 feet bgs then fine-grained sand, with stringers of clay and silt extending to 45 feet bgs based on soil boring logs from the property.
Groundwater data has been collected since the first set of monitoring wells were installed in 2009. Benzene and MTBE are the only VOCs that historically have been present at concentrations that exceed any applicable regulatory standards. In 2016, CBN™ and CARBSTRATE™ nutrient amendments were introduced into MW-6 to assist in the biodegradation of the MTBE in the groundwater. Groundwater sampling results showed significant decrease of contamination in MW-6 as of April 2017.
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Public Comment Period
Dates: May 26, 2017 – June 26, 2017
Comments may be submitted as follows:
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By Mail (Must be postmarked or received by June 26, 2017):
Waste Programs Division
1110 W. Washington Street
Phoenix, AZ 85007
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