PUBLIC HEALTH ASSESSMENT
MARINE CORPS AIR STATION YUMA
YUMA, ARIZONA
| ACM | asbestos-containing material |
|
ADEQ |
Arizona Department of Environmental Quality |
|
AS/SVE |
Air sparging/soil vapor extraction |
|
ATSDR |
Agency for Toxic Substances and Disease Registry |
|
BTEX |
benzene, toluene, ethylbenzene, and total xylenes |
|
CALA |
Combat Aircraft Loading Apron |
|
CAOC |
CERCLA Area of Concern |
|
CERCLA |
Comprehensive Environmental Response, Compensation, and Liability Act of 1980 |
|
CREG |
cancer risk evaluation guide |
|
CVs |
comparison values |
|
DCA |
1,1-dichloroethane |
|
DCE |
1,1-dichloroethene |
|
EPA |
United States Environmental Protection Agency |
|
FFA |
Federal Facilities Agreement |
|
FFAAP |
Federal Facilities Agreement Assessment Program |
|
FS |
feasibility study |
|
MCAS |
Yuma Marine Corps Air Station Yuma |
|
OU |
operable unit |
|
PAHs |
polynuclear/polycyclic aromatic hydrocarbons |
|
PCB |
polychlorinated biphenyls |
|
PCE |
tetrachloroethene |
|
PHA |
Public Health Assessment |
|
PHAP |
Public Health Action Plan |
|
RI |
remedial investigation |
|
RMEG |
reference dose media evaluation guide |
|
ROD |
record of decision |
| SVOCs |
semivolatile organic compounds |
|
TCE |
trichloroethylene |
|
TPH |
total petroleum hydrocarbons |
|
UST |
underground storage tank |
|
VEMUR |
Voluntary Environmental Mitigation Use Restriction program |
|
VOCs |
volatile organic compounds |
Marine Corps Air Station Yuma (MCAS Yuma) is located on the northern portion of the Yuma Mesa, southeast of the city of Yuma, Arizona. It occupies about 3,000 acres, roughly 4 to 5 miles from, and 60 to 70 feet above, the Colorado River. MCAS Yuma has been used primarily for military purposes from 1941 through the present, and has been operated by the U.S. Department of the Navy since 1959. A variety of hazardous wastes have been handled, stored, and disposed of at MCAS Yuma, resulting in soil and groundwater contamination at a number of locations. The station is fenced at the perimeter and is not open to the public.
Areas of potential concern at MCAS Yuma were used for waste disposal, vehicle maintenance and repair, hazardous materials storage, fire training, pest control, and general industrial purposes. The Agency for Toxic Substances and Disease Registry (ATSDR) conducted site visits in February 1991 and February 1997. Based on information gathered during the site visits, ATSDR identified three potential exposure pathways: exposure to contaminated groundwater; exposure to asbestos-containing material (ACM) at the Radar Hill Disposal Area; and exposure to organic lead in surface soil at the Flight Line, Shops Area, and Fire School Area. This public health assessment (PHA) evaluates the potential public health hazards associated with these three pathways.
Exposure to Contaminated Groundwater
Although the groundwater at MCAS Yuma is contaminated, no one has ever been exposed to the contaminated water. Drinking water is supplied to MCAS Yuma directly from the Colorado River, via a canal system. Berms protect the canals' banks, so contamination from runoff is not a concern. Every year, for about two weeks, the canals are closed for cleaning, and an alternate source of water must be used. Since 1996, the station has relied on water from the city of Yuma during this period, which gets its water from the Colorado River via its own canal system. Until 1996, drinking water at MCAS Yuma was supplied from an on-site well during the canal-cleaning period. The on-site well is located upgradient of the major contaminant plumes underlying the station. All drinking water on the station has always met federal drinking water standards. For these reasons, ATSDR concludes that exposure to contaminated groundwater at MCAS Yuma does not pose a past, current, or future public health hazard. However, should new wells be drilled at MCAS Yuma, the potential for exposure to contaminated groundwater should be reevaluated.
Contaminated groundwater from MCAS Yuma will not pose a public health hazard to individuals who use groundwater drawn from locations downgradient of the station for two reasons: 1) the contaminant plumes have not traveled beyond the station perimeter, and 2) contaminated groundwater will be remediated and barriers will be developed to prevent plumes from migrating off station.
Exposure to Asbestos-Containing Material (ACM) at the Radar Hill Disposal Area
The Radar Hill Disposal Area was used in the 1940s and 1950s for general disposal of the station's trash and more recently for the disposal of construction debris, some of which contains asbestos, a known carcinogen. Some warning signs have been posted and some fencing is present. Since the quantity of ACM is limited, and most of the ACM is buried, exposure was and continues to be fairly limited. In the future, the ACM will be removed and the soil cleaned up, eliminating any future public health hazard. The Navy has planned and budgeted removals in 1998 for CERCLA Areas of Concern (CAOCs) 4A and 4B in the Radar Hill Disposal Area, CAOCs 7A and 7B in the Fire School Area and debris piles south of the combat Aircraft Loading Apron, and CAOC 9, the Horse Stable Area. For these reasons, ATSDR concludes that exposure to ACM at the Radar Hill Disposal Area does not pose a past, current, or future public health hazard. ATSDR recommends that additional warning signs be installed at Site 4B to help ensure limited potential exposure until cleanup of ACM is complete.
Exposure to Organic Lead in Surface Soil
The predominant source of organic lead in the environment is the use of tetraalkyl lead compounds (primarily tetraethyl lead) as anti-knock additives in gasoline. MCAS Yuma has not purchased leaded gasoline since 1987. Although tetraethyl lead is very toxic, it also generally degrades in soil within a matter of months, so any organic lead currently present at the station is likely in the form of mineralized ionic ethyl lead breakdown products of tetraethyl lead. The toxicity of these compounds is not known.
In 1995, the Navy sampled for organic lead at 11 sites that were suspected of having vehicle-related waste streams. Organic lead was detected in five surface soil samples (one of which was a field duplicate) and one subsurface soil sample from the Flight Line, Shops Area, and Fire School Area. None of these areas has the potential for current or future human exposure, but past exposures at the Shops Area and Fire School Area may have occurred. Although current and future exposures are not a concern, the high levels of organic lead present in these areas raise concerns about potential past exposures. ATSDR does not have sufficient information at this time to evaluate potential public health impacts, therefore, past exposure to organic lead in surface soil presents an indeterminate public health hazard.
Exposure to Other Areas of Potential Concern
ATSDR evaluated a number of additional areas of potential concern at MCAS Yuma and
off-station. Appendix A contains a list of these areas. ATSDR has determined that these areas,
which
include every evaluated off-station area, do not present a public health hazard based on one or
more of the following reasons: 1) no contaminants were detected, 2) contaminants were detected
at concentrations
that are too low to pose a health hazard, 3) access to the area was (past
scenario), is (current scenario), and will be (future scenario) highly restricted, and/or 4) impacted
areas have been or will be remediated.
Site Description and Operational History
Marine Corps Air Station Yuma (MCAS Yuma) is located on the northern portion of the Yuma Mesa, southeast of the city of Yuma, Arizona. It occupies about 3,000 acres, roughly 4 to 5 miles from, and 60 to 70 feet above, the Colorado River. A variety of hazardous wastes have been handled, stored, and disposed of at MCAS Yuma, resulting in soil and groundwater contamination at a number of locations. The station is fenced at the perimeter and is not open to the public.
MCAS Yuma has been used as an airfield since 1928. Between 1941 and 1946, the facility was leased to the U.S. Army Air Corps for pilot and bomber crew training. After a brief period of disuse, the area was used as a civilian airfield from 1948 to 1951, at which time it was reactivated by the U.S. Air Force as a Weapons Proficiency Center for fighter-interceptor units. In 1959, the site was transferred to the U.S. Department of the Navy, and MCAS Yuma was established to provide support for the Marine Aircraft Wing and its subordinate units. The airport is currently operated as a joint military/civilian facility. Aircraft and site maintenance, fire training, and industrial and waste disposal activities generated a variety of toxic wastes, including industrial solvents, airplane fuel and oil, lubricants, paint strippers, and pesticides. Asbestos-containing material (ACM) was also used for construction (JEG, 1996; Stearns, 1985; Uribe, 1996, 1997a).
Remedial And Regulatory History
Site investigations were initiated in 1985 to evaluate past disposal sites at MCAS Yuma. Preliminary studies indicated the presence of chlorinated solvents in underlying groundwater. Because of these results, in 1990, the U. S. Environmental Protection Agency (EPA) placed MCAS Yuma on the National Priorities List. In 1992, the Navy entered into a Federal Facilities Agreement (FFA) with EPA and the Arizona Department of Environmental Quality (ADEQ) to establish a framework and schedule for implementing environmental investigations and appropriate cleanup actions specified in the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). EPA is the lead regulatory agency for the remediation of MCAS Yuma. ADEQ is the supporting state regulatory agency for these activities (Uribe, 1997a).
Major environmental investigations at MCAS Yuma are being conducted under three separate programs:
The investigations planned under the FFA have largely concentrated on two operable units (OUs). OU1 consists of soil below 10 feet and the groundwater underlying the station. OU2 consists of the first 10 feet of soil below ground surface.
The remedial investigation (RI) for OU1 was completed in 1996. The parties to the FFA have not yet finalized the feasibility study (FS) which evaluates possible remedial alternatives. A record of decision (ROD) will follow the FS and should be finalized in the fall of 1998. The RI identified seven contaminated groundwater plumes (see Figure 4), four of which will be addressed in the FS. The remaining three plumes were referred to the Underground Storage Tank (UST) program (see below) for further action (JEG, 1996; Yuma, 1997a, 1998a).
The FS for OU1 will soon be completed and the Proposed Plan (to be released this summer) will outline a plan for the Navy to remediate the contaminated plumes through a combination of active measures and monitored natural attenuation. Since the plume in Area 1 has reached the station perimeter, the plan calls for the Navy to contain this plume through the use of vertical recirculation wells. The Navy plans to remediate hot spots in the Area 1 plume through mass removal by using air sparging/soil vapor extraction (AS/SVE). After a five-year review, if natural attenuation has not been successful in the center of this plume and in other plume areas, a contingency plan calls for the Navy to remediate contamination using pump-and-treat techniques (Yuma, 1998a; JEG, 1998a).
A ROD was signed for OU2 in late 1997. Of the 18 sites investigated in OU2, three sites containing ACM (sites 4, 7, and 9) will be cleaned up and three sites with other contaminants (sites 1, 8, and 10) will be subject to permanent future use restrictions. Appendix A contains a detailed list of sites in OU1 and OU2 (Uribe, 1997a).
MCAS Yuma initiated the UST program in 1989 to remove all active and inactive USTs on site. The program was also charged with excavating and removing high-risk USTs, assessing sites, and recommending corrective actions. The major groundwater remedial work of the UST program has been the cleaning up of four contaminated groundwater plumes associated with the Exchange Service Station, Fuel Farm Area, Motor Transportation Pool, and leaking pipe near Building 310. JP-5 jet fuel and fuel constituents (primarily benzene, toluene, ethylbenzene, and total xylenes [BTEX]) make up the primary groundwater contaminants. The Navy has completed groundwater remediation of BTEX, using air sparging and vapor extraction, at the Exchange Service Station and the Motor Transportation Pool plumes. They have recommended continued monitoring, natural attenuation, and biosparging. The Navy is still actively remediating the Building 310 plume, using vapor extraction and pumping, and the Fuel Farm Area plume, using vapor extraction and air sparging (JEG, 1996; OHM, 1998a; Yuma, 1998a,b).
The Federal Facilities Agreement Assessment Program (FFAAP) is a comprehensive review and assessment of current and past waste-generating activities at the station. The FFAAP initially reviewed 559 sites and addressed 36 of these sites in more detail. Of the 36 sites, the FFAAP recommended three sites for future use restrictions under the Arizona's Voluntary Environmental Mitigation Use Restriction (VEMUR) requirements. The program recommended two other sites for further remedial action. Appendix A shows charts of these five actionable sites in more detail. Sites reviewed under the FFAAP and located within the boundaries of the 18 OU2 sites were incorporated into the RI for OU2 (Southwest Division, 1997).
Local Demographics and Land Use
The Agency for Toxic Substances and Disease Registry (ATSDR) used 1990 census data to compile the demographic information in Tables 1 and 2. The population of the city of Yuma in 1990 was 54,923. The city's population more than doubles during the winter months, when the area is a popular haven for senior citizens from colder climates. A majority (58.5%) of households were owner occupied, and 12.7% of households lived in mobile homes.
About 6,300 people work on the station, including about 1,100 are civilians. Roughly 2,700 people live in station-owned housing; of these, about 1,000 are children. MCAS Yuma owns 821 family housing units, of which 128 are located off station. On average, families reside in on-station housing for about 3 years during a typical tour of duty. It is unusual for anyone to serve more than three tours of duty at MCAS Yuma. A large number of Armed Forces personnel come through MCAS Yuma each year for training (Stearns, 1985; Yuma, 1998e,h).
MCAS Yuma is located in the southwestern corner of the state of Arizona, in close proximity to the borders of California and Mexico. Located on the Yuma Mesa, the station is directly to the southeast of the city of Yuma, Arizona. It occupies about 3,000 acres, roughly 4 to 5 miles from, and 60 to 70 feet above, the Colorado River.
MCAS Yuma is located in the Sonoran Desert. The environment in the area of MCAS Yuma is dominated by desert plains, with low stands of creosote bush interspersed with bur sage. There is no natural surface water on the station, and the water canals do not traverse the base. Most of the station property has been developed or disturbed. Little vegetation grows around the buildings and residences, and there are few landscaped areas. Some residents of the station-owned housing units maintain gardens, although few vegetables are grown. Some residents fish in the water canals, although a permit is necessary to do so. While there is no hunting at the station, some residents may be eating rabbits (Stearns, 1985; Yuma, 1998a,e,g).
The station airport is operated as a joint military/civilian facility. The civilian portion is growing and becoming more developed. The Navy also leases 90 acres of the station's property for agricultural use. This property has always been used for agricultural purposes, and has not been impacted by operations at MCAS Yuma.
The majority of the land immediately surrounding the station contains irrigated citrus groves, although commercial and industrial sites predominate to the north, and some residential areas exist to the north and east (Stearns, 1985).
The ATSDR conducted site visits in February 1991 and February 1997. ATSDR staff met with a number of station personnel, state officials, and representatives from the Navy. Based on information gathered during the site visits, ATSDR identified two potential exposure pathways of concern at MCAS Yuma: exposure to contaminated groundwater and exposure to ACM at the Radar Hill Disposal Area. This Public Health Assessment (PHA) evaluates the potential public health hazards associated with these two pathways as well as a third potential pathway, organic lead in the surface soil, which was later identified. No community health concerns were identified during ATSDR's site visits.
Quality Assurance and Quality Control
In preparing this PHA, ATSDR relied on the information provided in the referenced documents and by contacts. The agency assumes adequate quality assurance and control measures were followed with regard to chain-of-custody, laboratory procedures, and data reporting. The validity of the analyses and conclusions drawn in this document are determined by the availability and reliability of the referenced information.
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