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PUBLIC HEALTH ASSESSMENT

HOMESTEAD AIR FORCE BASE
HOMESTEAD, DADE COUNTY, FLORIDA


SUMMARY

Homestead Air Force Base (Homestead AFB) is located approximately 25 miles southwest of Miami and seven miles east of the city of Homestead in Dade County, Florida. The Homestead Army Air Field was activated by the Air Force in September 1942, and used for transport and training. After a severe hurricane in 1945, the base was owned by Dade County Port Authority until the federal government reacquired it in 1953. In 1992, a second severe hurricane, Andrew, destroyed most of Homestead AFB. Currently, the U.S. Air Force Reserve occupies approximately one third of the base for daily operations and training facilities. The remainder of the property is being parceled out for various industrial and commercial uses.

The topography of Homestead AFB is flat and surface drainage is poor. To assist drainage, canals have been constructed throughout Homestead AFB. These canals drain to the Boundary Canal, which surrounds most of the base, then into a stormwater reservoir, and finally into the Outfall Canal. The Outfall Canal flows east two miles from the edge of the base property and empties into the Biscayne Bay.

The Agency for Toxic Substances and Disease Registry (ATSDR) conducted an initial site visit in 1991 and a second site visit in 1997. During these visits, no completed pathways of human exposure were identified. Community concerns regarding Homestead are generally ecological concerns about contaminants in the canal system affecting Biscayne Bay.

ATSDR reviewed on-site groundwater data. Elevated levels of volatile organic compounds (VOCs), base/neutral and acid extractable compounds (BNAs), pesticides, and metals exist in groundwater under Homestead AFB at generally very low quantities. No exposure to contaminated drinking water is occurring currently or will occur in the future. Due to salt water intrusion, the base drinking water has been supplied by off-base wells since 1992. No drinking water wells will be placed on the base in the future. ATSDR suggests placing a ban on future drinking water wells at Homestead AFB. On the basis of currently available data, ATSDR concludes that contaminants in groundwater do not pose a health hazard because no pathway for exposure appears to exist.

ATSDR reviewed on-site soil data. Although levels of polycyclic aromatic hydrocarbons (PAHs), pesticides, and metals were detected above comparison values in some samples, detections occurred in areas of limited access (e.g., industrial areas) and were detected sporadically and at levels that do not pose a health hazard. On the basis of available data, ATSDR concludes that exposure to contaminants in soil does not pose a public health hazard.

ATSDR performed a detailed review of surface water, sediment, and fish data from the Boundary and Outfall Canals. Surface water samples contain sporadic detections of a few metals. Sediment samples contain PAHs, polychlorinated biphenyls (PCBs), and metals. Limited exposure to contaminants at detected levels in surface water and sediment during recreational activities such as fishing is not likely to pose a health hazard. On the basis of available data, ATSDR concludes that exposure to contaminants in surface water and sediment does not pose a public health hazard. Fish samples contain PCBs, pesticides, and arsenic. Ingestion of contaminants at levels detected in fish from the canal system is not likely to pose a health hazard for individuals who infrequently ingest fish from the canals. However, it is possible (though unlikely) that ingesting large quantities of fish from the canal (such as subsisting on canal fish) may be associated with noncancer health effects. On the basis of available data, ATSDR concludes that occasionally ingesting fish from the Boundary or Outfall Canals does not pose a public health hazard, but that adverse health effects may be associated with ingesting fish at a subsistence level.


BACKGROUND

Site Description and History

Homestead Air Force Base (Homestead AFB) is located approximately 25 miles southwest of Miami and seven miles east of the city of Homestead in Dade County, Florida (see Figures 1 and 2). The main installation covers approximately 2,940 acres with easements covering an additional 429 acres (Air Force, 1993; Geraghty & Miller, 1994a).

Pan American Air Ferries originally developed the air field at Homestead AFB and for a few years used the site for pilot training. In September 1942, the Homestead Army Air Field was activated for the Caribbean Wing Headquarters. The base served as a staging facility for the Army Transport Command, which was responsible for maintaining and dispatching aircraft to overseas locations. In 1943, the field mission was changed to train transport pilots and crews for the Second Operational Training Unit (Geraghty & Miller, 1994a).

A severe hurricane caused extensive damage to the air field in September 1945, and the base was placed on inactive status and transferred to Dade County. Dade County Port Authority owned and managed the base for eight years, during which time the runways were used by crop dusters and the buildings housed a few small industrial and commercial operations (Geraghty & Miller, 1994a).

In 1953, the federal government again acquired Homestead AFB, rebuilt it as a Strategic Air Command base, and reactivated it in November 1955 (Geraghty & Miller, 1994a). The base was operated by Air Force strategic and tactical units until August 1992, when Hurricane Andrew rendered 97 percent of the base dysfunctional (Air Force, 1993). The base was placed on the 1993 Base Realignment and Closure list and given a reduced mission (Air Force, 1993).

On April 1, 1994, part of the base officially became Homestead Air Reserve Base. Approximately one-third of the base is currently occupied by the U.S. Air Force Reserve 482 Fighter Wing and used for daily operations and training facilities. The Florida Air National Guard occupies a small parcel of land near the north end of the base's flightline. Most of the remaining two-thirds of the property, or 2,055 acres, is presently under an interim short-term lease to Dade County until final disposition of the property can be carried out (Woodward-Clyde, 1997b). Land transfers have already occurred from the Air Force to the U.S. Department of Labor (41 acres), Dade County Homeless Trust (84 acres), Florida Power and Light, and a bank and credit union. Proposals for the remaining two-thirds of the installation are being considered for Dade County Aviation Department (approximately 1,600 acres), Dade County Parks and Recreation (213 acres), and Dade County Public Schools for industrial use and trade schools (26 acres) (see Figure 3).

Homestead AFB was already engaged in the Installation Restoration Program (IRP) developed by the Department of Defense when it was placed on the U.S. Environmental Protection Agency's (EPA) National Priorities List on August 30, 1990. To establish a framework and schedule for developing, implementing, and monitoring appropriate remedial actions at the base, a Federal Facility Agreement was signed by Homestead AFB, the EPA, and the Florida Department of Environmental Protection in March 1991.

Through the IRP, 27 sites were identified with known or suspected contamination. Twenty of these sites are being investigated and remediated as needed in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Seven other sites are being investigated and remediated as needed under the Florida Department of Environmental Protection Petroleum Contamination Site Cleanup Criteria and one was proposed and accepted for closure under the Resource Conservation and Recovery Act (RCRA) (Air Force, 1993). Several additional sites were identified after Hurricane Andrew damaged the base and are also being investigated and remediated as needed under these programs. The 1994 RCRA Facility Assessment identified 64 potential sites, of these, 37 were recommended for confirmation sampling. As a result of confirmation sampling, 15 sites were recommended for no further action, 9 were transferred to the Florida Fuels Program, and 13 were recommended for further investigations.

Natural Resources and Land Use

Homestead AFB is relatively flat with elevations ranging from approximately five to ten feet above mean sea level. Local variations in relief of the topography at the base are typically the result of construction activities (Geraghty & Miller, 1994a). Because the groundwater table is at or above the ground's surface in south Florida, the landscape is dominated by broad swamps and typically exhibits poor surface drainage. Approximately 100 acres of land at Homestead AFB have been identified as wetlands. Because of the poor drainage, numerous canals have been constructed at Homestead AFB. These canals improve surface water drainage, divert rainfall runoff, and lower the water table in some areas. The hydraulic gradient of the canal system is 0.3 feet per mile. Water in the canals is essentially stagnant and no measurable flow occurs. In response to significant precipitation events, however, a slight hydraulic gradient is induced and some flow occurs in the canals (Woodward-Clyde, 1995).

The Boundary Canal surrounds all but a portion of the base (see Figure 2). A dike was constructed along the outside of the bank of the Boundary Canal to prevent runoff from outside the base from entering the canal (Geraghty & Miller, 1994a). A drainage divide occurs within the base property, running from the northern end toward the center. Water in the Boundary Canal generally flows south and east along the western boundary and south along the eastern boundary, converging at the stormwater reservoir located on the eastern side of the base.

Water flows through water-control structures out of the stormwater reservoir into the Outfall Canal. The Outfall Canal flows east from the base for approximately two miles and empties into Biscayne Bay (Geraghty & Miller, 1994a). The land between Homestead AFB and Biscayne Bay is composed of farmland, nurseries, woodlands, and forested wetlands. Homestead AFB and these lands are part of the drainage basin for the canal. Biscayne Bay is part of the Biscayne National Park.

Two other surface water bodies are located on Homestead AFB. Mystic Lake is located near a former recreational campground and trailer area. Mystic Lake may have been used in the past for both recreational and fishing purposes (ATSDR, 1997b; ATSDR, 1997c). Phantom Lake is located near a controlled area where access is limited. Recreational fishing may have occurred or may be occurring at Phantom Lake (ATSDR, 1997b; ATSDR, 1997c).

The area adjacent to the Boundary Canal surrounding Homestead AFB to the east, west, and south is primarily composed of farmland and commercial nurseries (Woodward-Clyde, 1997b). Land use adjacent to the northern and western borders of the base includes residential and commercial facilities within the city limits of Homestead. Homestead AFB is surrounded by a fence.

The Biscayne Aquifer is the primary source of drinking water in southern Florida. The aquifer ranges from 80 to 120 feet below land surface around Homestead AFB. It consists of highly permeable limestone, sandstone, and sand. The Biscayne Aquifer is recharged by rainfall and canals in dry periods, but also discharges to canals and coastal seepage. Since the Aquifer has a unique relationship with the canals and Atlantic Ocean, it is subject to saltwater intrusion.

Demographics

Approximately 700 personnel, half military and half civilian, currently work at Homestead AFB. An additional 200 to 300 Reservists are also at the base for training, but are not full-time employees. It has been projected that approximately 1,000 civilian Homestead AFB employees and 2,000 Reservists will be employed at the site in the future (Woodward-Clyde, 1997b). Additional Reservists will be visiting for training for short periods (Woodward-Clyde, 1995). The population of the city of Homestead is approximately 18,700 (Woodward-Clyde, 1997b).

Quality Assurance and Quality Control

In preparing this public health assessment, ATSDR relies on the information provided in the referenced documents and 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. The limits of these data have been identified in the associated reports.

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