Juneau Airport Fueling Storage Facility
|Summary Date: November 2007||View detailed information from database on this site.|
|Status: Active||Database Name: Delta Western Juneau Airport Fuel Storage|
|Location: 9203 Cessna Drive, Juneau, Alaska||Latitude/ Longitude: See database entry above|
| DEC Contaminated Sites Contact: Bruce Wanstall, Project Manager– 907-465-5210
The Juneau Airport Fueling Facility contaminated site is a former Chevron bulk fuel terminal located on a tract of land in the northern portion of Juneau International Airport at 9203 Cessna Drive in Juneau. Delta Western and Aero Services currently maintain bulk fuel terminals in the tract, providing fuel services to the airport.
The former Chevron bulk fuel terminal consisted of two 25,000-gallon aboveground storage tanks (ASTs) and a 25,000-gallon underground storage tank (UST). The ASTs contained jet fuel and the UST contained aviation gasoline. Chevron operated the fuel terminal from 1958 to 1987 and then sold the equipment to Delta Western, who continued to operate the facility. In 1998, Delta Western constructed a new bulk fuel facility 100 feet southeast of the former Chevron tanks. Once the new equipment was operational, the three former Chevron tanks were removed. That is when petroleum soil contamination was discovered. Chevron promptly began a site investigation to clean up soil contaminated by the leaking underground tank. Nearly all of the contaminated soil was dug up and shipped off-site for remediation.
In order to assess impacts to groundwater from residual soil contamination that remained after the site cleanup, three monitoring wells were installed on the tract. One monitoring well (MW-4) was placed next to the former leaking underground tank footprint and two sentinel wells were installed at the perimeter of the tract. A survey of the wells determined that groundwater flow gradient was to the west. The sentinel wells were removed after yielding consistently clean test results, while MW-4 consistently had diesel range hydrocarbons (DRO) above regulatory levels. The source of the persistent contamination in the groundwater remained uncertain but appeared to be stable and not posing an unacceptable risk to human health or the environment. The DEC approved a long-term plan to use monitoring well MW-4 to monitor of the natural breakdown of the contaminated groundwater.
In the spring of 2006, a property assessment for new construction within the Juneau International Airport tract on Lots 4 and 5 revealed that a layer of petroleum contamination had migrated on the groundwater northward from the former Chevron underground tank site. The unexpected discovery prompted Chevron to consider the possiblity that contamination could have spread to nearby residential water wells. Chevron also installed an active groundwater remediation device in MW-4 to accelerate natural breakdown of the residual diesel range hydrocarbon.
Public Health and Environmental Concerns
A mixed commercial and residential area surrounds the northern portion of the Juneau International Airport. Duck Creek, an anadromous stream, flows along the east side of the tract. In order to evaluate any potential risk associated with the remaining petroleum contamination at the former bulk fuel terminal facility, Chevron has developed a conceptual site model to identify ways in which humans and/or wildlife could be exposed to the contamination.
The City and Borough of Juneau public water system serves the general area. In order to firmly address questions raised by the conceptual site model, however, Chevron’s environmental consultant Conestoga-Rovers & Associates (CRA) conducted a door-to-door survey within a 1/2-mile radius of the site where historical data identified the potential presence (and use) of 66 water wells. In the event residents were not available during the survey, well survey questionnaires were left on the premises. Completed questionnaires were later returned and evaluated by CRA. One private well was identified as a potable water supply that was in use. Monitoring data indicate that with low groundwater velocities and distance from the site, it is highly unlikely that contamination from the facility has impacted the identified drinking water well.
In 2006, the DEC approved a Soil and Groundwater Management Plan that CRA developed for Chevron in the event that any future development at the Juneau International Airport tract encounters contaminated material relating to the former UST site. In 2007, CRA installed an ozone injection remedial system in monitoring well MW-4 to initiate groundwater remediation for the stable diesel range organics plume.
The solar-powered ozone injection device operates by drawing air from the surface down into a cold-corona discharge chamber where ozone is generated and mixed with air at a rate of one to two percent by volume. The mixture is injected from the device into surrounding groundwater through an inert fine-pore, heat-bonded silica diffuser. The diffuser creates bubbles 0.5 to 2 millimeters in diameter that rise through the surrounding saturated soil, scrubbing sorbed residual petroleum hydrocarbons from soil particles and stripping volatile organic compounds from the groundwater.
In 2007, groundwater sample test results from monitoring well MW-4 were above regulatory groundwater cleanup levels for diesel range organics; the next annual groundwater monitoring event for MW-4 is June 2008. In November 2007, samples were collected from the potable water well for laboratory tests, and data was collected from the ozone injection device in MW-4. The results of this monitoring effort will be used to ensure that the risk of exposure to human health is not present and to evaluate the effectiveness of the active treatment system in removing the diesel range organic contamination from the groundwater.