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Air Force Plant 44 Site
Site Overview, Updates, and Remaining Concerns
The Tucson International Airport Superfund Site has been polluted for decades with
industrial wastes, and is now undergoing remediation, or cleanup. The Air Force Plant 44
site is one of seven subsections of this larger area, which has exhibited serious soil and
groundwater pollution for decades. Remediation is still ongoing at the AFP 44 site, though
some parts of it have been declared as clean. This document a) reviews the history of the
site, including an explanation of what pollutants are present, b) reviews the most recent
cleanup agreement for the site, and c) reviews progress that has been made on this cleanup
and remaining concerns.
Site History and Cleanup Agreement
AFP-44 (circled in red on the map) is a former weapons manufacturing site that was
owned by government the governed and
operated by the Raytheon Company. It is a
part of the larger Tucson International
Airport Area Superfund site, which has a
large plume of groundwater pollution
approximately 4 miles long, and primarily
composed of trichloroethylene but also
including 1,4-dioxane, tetrachloroethene
(PCE), dichloroethene; (1,1-DCE),
chloroform, carbon tetrachloride, benzene
and chromium. The larger site is divided
into seven project areas of which AFP-44 is
one. Various polluting activities have
occurred on the AFP-44 site including
treatment and storage of wastewater; the placement of waste in unlined storage
impoundments; and the disposal of toxic wastes on the surface of the site. The soil at the
site is polluted, and polluted groundwater has flowed beyond the border of the site.
Pollutants at the AFP-44 site include the following:
1) 1950s: Chromium was found in the water supply.
2) 1981: Volatile Organic Compounds or VOCs, which can have harmful health
effects, were found in the groundwater and soils. Trichloroethylene (TCE) a toxic
industrial solvent and human carcinogen, was found in the groundwater.
3) 1995: Heavy metals including cadmium, chromium and lead were found in soil at
the site.
4) 2000-2004: 1,4-dioxane, a probable human carcinogen (Group 2B), DX has shown
to produce carcinomas of the nasal cavity and liver in multiple strains of rats, liver
carcinomas in mice, gull bladder carcinomas in guinea pigs. The National Institute of
Environmental Health Sciences has determined that DX is reasonable anticipated to
be a human carcinogen. Damage to the liver and kidneys has been observed in rats
chronically exposed to DX in drinking water.
5) Other contaminants
identified at the site
include TCA, DX,
chloroform; benzene;
and nickel; and cyanide.
The AFP-44 site, On April 3,
1986, USAF issued a Remedial
Action Plan for cleanup of the groundwater, which provided for a groundwater extraction
and treatment plant using air stripping and carbon adsorption designed to remove both
chromium and chlorinated solvents from extracted groundwater at rates up to 5,000
gallons per minute. the Airport site as a whole, has been addressed in two stages,
immediate and ongoing cleanup. Over the years a number of cleanup activities have been
conducted, including methods to pump, treat and blending
the polluted groundwater, methods to extract VOCs, January 2004, according to an
Administrative Order for response action issued to the United States Air Force and
Raytheon Company the extraction and treatment system was not effective at containing
the contaminated groundwater plume from Air Force Plant 44, allowing TCE and DX to
migrate north into the tarp system . Because this engineer blending strategy not effective in
containing the contaminated groundwater plume from AFP44, this order compels the
Respondents to conduct measures to abate the threat to public health presented by the
past and present contamination from the AFP44 which is located in Tucson, Arizona
(“AFP44”),by performing the response actions described as the scope of work (”SOW”),
incorporated herein as Appendix A to this Order, methods to excavate contaminated soils,
and methods to degrade contaminants at the site. Metals and VOCs are still a concern at the
site. In 2011 an agreement was established between the U.S. EPA Region 9, the State of
Arizona, and the Air Force to address ongoing cleanup of the site and lay out actions to be
performed.
The above map shows a closer view of the AFP44 Site.
Review of Cleanup and Recent Updates
In 2013, the US EPA released the first five-year report for the Tucson International
Airport Area Superfund Site, which aimed to “review information and determine if the
remedy is and will continue to be protective of human health and the environment.” The
document assessed whether the actions taken at the AFP-44 site had been successful in
containing polluted groundwater. According to the report, the VOC plume is decreasing in
size and 24,000 pounds of VOCs have been removed since 1987. They also have removed
an estimated 54 pounds of 1,4-dioxane. They stated that the extent of the chromium
contamination has decreased though there are wells within the plume with Cr values above
maximum concentration levels. Overall, they indicated that the remedial actions were
working as expected, with contaminant levels decreasing or remaining stable and
movement of contaminants being contained. Chromium levels were a continuing concern.
The study was positive about the effects of remediation but also stated there are no
existing risk assessments specifically for exposure to groundwater at AFP-44
The document also listed updates on the risk assessments that have previously been
performed at other areas of the TIAA site. They identified 1,4-Dioxane as an emerging
contaminant that was not considered at the time of the last assessment, and stated that it
was not yet formally included in the plan; therefore, a more comprehensive assessment of
1,4-dioxane in the groundwater was necessary. They also discussed the possibility for
vapor intrusion, which has been better understood by the EPA in recent years, and
recommended this as a focus of analysis before the next five-year review.
The most recent updates at the project website
(
https://www.azdeq.gov/environ/waste/sps/Air_Force_Plant_44_Raytheon_Project_Area.h
tml#ssu) discuss that the groundwater treatment system continues to operate to this day.
It has treated 29.4 billion gallons of groundwater between 1987 and September of 2014.
Offsite 1,4-dioxane contamination is being treated as well. January 2013, completing
construction of a new Advanced Oxidation Process (AOP) Water Treatment Facility Plant
and the existing Tucson Airport Remediation Project (TARP), facilities will work in
conjunction to remove 1,4-dioxane and other contaminants from water according to the
December 2013, Tucson Water Reports, October Water Quality Report.
One section of the site, a former pistol range, was declared clean during the fall of
2014, though community concerns have continued. The site was primarily contaminated
with lead, and in late 2014 the remediation team reported that all lead levels are below the
screening level of 400 ppm for residential soil recommended by the Arizona Department of
Environmental Quality.
Most recently, the Air Force has also begun studies to test a new method to treat
groundwater contamination in the fine-grained soils beneath the AFP-44 site. This
technique is described on the project website as “hydraulically fracturing and in-situ
treatment.” This process uses similar methods as the more well-known hydraulic
fracturing used for natural gas development, but it is aimed at removing or treating
contaminants at polluted sites. The process injects pressurized water into sediments,
creating cracks and passageways that can enhance the efficiency of both in-situ
remediation methods (cleaning up contaminants in the site) and of extraction (removing
contaminants). More information about the hydraulic fracturing process as used for site
cleanup can be viewed here: http://epa.gov/tio/download/remed/fractur.pdf. More
information is required to understand the exact technologies and any chemicals being used
at the AFP44 site, to understand where and when they are being used, and to understand
any potential releases of pollutants that might occur from this process. From an email
correspondence between Linda Robles and David Bell on February 19th, the hydrology
fracturing process started in August 2014 and is expected to be completed in April.
Summary of Concerns
The Air Force Plant 44 Site and the larger Tucson International Airport Area
Superfund Site have been highly polluted with organic compounds and metals for decades.
The EPA, the Air Force, and the Arizona DEQ have undertaken both immediate and long-
term efforts to control and remove pollution by treating and/or extracting polluted soil or
groundwater. Ongoing water treatment continues at the site, and the Air Force is
continuing to explore new treatment methods including environmental hydraulic
fracturing.
Community concerns remain over the nature of the cleanup efforts, particularly the
hydraulic fracturing process and whether there is potential for increasing the availability of
site contaminants through this method. Community members have also expressed
concerns about whether the process is being done at the recently-closed pistol range, and
whether it might mobilize contamination there. More transparent information on the
hydraulic fracturing process and its potential risks would be helpful in addressing
community concerns relating to the remedial process.
In addition, concerns have been raised about links between site contamination and
human health issues experienced by residents. It can be difficult to prove these links, but
with a site characterized by such long-term pollution it is a real concern. The potential of
links between human health effects and contamination should be investigated to help
address any injustices that have occurred throughout the history of this site, while
ensuring that continuing remedial activities do not present further risks to health of
residents. The City of Tucson is blending DX-contaminated water (from the South Field,
averaging 8ppb) with water from another extraction well field that is not contaminated
with DX (the North Field, presently less than the one ppb detection limit), Because of this
engineered blending strategy Central Arizona Project (CAP) blend of recharged water and
groundwater , if a North Field extraction well shuts down for any reason, including routine
maintenance, then the South Field extraction well also must shut down. The public and
community question in the event of a Main Water Break will the South and North well
fields be shut down to avoid any hazardous releases or threat of releases of contamination
from AFP44 which provides drinking water through TARP to the City of Tucson. Currently
the main distribution system is divided into 10 zones you can find this map and more
information on the October 2013 Tucson Water Quality Report.