NAVAL AIR STATION PATUXENT RIVER
ST. MARY'S COUNTY, MARYLAND
The Naval Air Station (NAS) Patuxent River is located in St. Mary's County Maryland, near the city of Lexington Park, and covers an area of approximately 6800 acres (10.5 square miles) bounded on the north by the Patuxent River, on the east and south by the Chesapeake Bay, and on the west by State Highway 235. The base population is about 15,900 persons, including military personnel and dependents, Department of Defense civilian employees, contractors, and nonappropriated fund employees. NAS Patuxent River is surrounded by security fencing and is routinely patrolled; access to the facility is through manned security gates.
Before the currently established environmental regulations, previously accepted hazardous material handling and disposal practices resulted in environmental contamination at various areas on base. As a result, NAS Patuxent River was listed on the U.S. Environmental Protection Agency's National Priorities List in June of 1994. The Navy had conducted an initial assessment of potentially contaminated areas in 1982 and established 31 original Installation Restoration Program (IRP) sites; 46 sites are currently included in the IRP. Base-wide investigations and site restorations continue under this program.
ATSDR evaluated the environmental information on the IRP sites and assessed the potential for human exposure at each site. The IRP sites pose no current public health hazard. (Appendix A presents information on ATSDR public health assessment hazard categories).
NO APPARENT PUBLIC HEALTH HAZARD
ATSDR concluded that one situation involving fish on the NAS Patuxent River installation poses no apparent public health hazard.
Available data for Pond 3 demonstrated significant levels in fish of polychlorinated biphenyls (PCBs) and of the chlorinated pesticide DDT and its degradation products DDE and DDD. Cancer-risk calculations based on an average concentration of 0.116 mg/kg PCBs yield a consumption limit for Pond 3 fish of 19 meals/year for a period of 7 years. An 8-ounce portion constitutes one meal.
INDETERMINATE PUBLIC HEALTH HAZARD
To evaluate possible health effects, data are needed to determine whether edible aquatic fauna are contaminated in on-base ponds 1, 2, 4, 5, and 6 and in the river, bay, and seaplane basins adjacent to NAS Patuxent River.
Of the remaining five on-base ponds, Pond 6 is used as a brood pond for stocking the others and Ponds 1, 2, 4, and 5 are fished. The limited data from these 5 ponds are insufficient to evaluate whether sediment or fish are contaminated. There are no data on whether PCBs are present in fish or sediment of ponds other than Pond 3. Because the source of PCBs in Pond 3 is unknown, it is recommended that a provisional consumption limit of 19 meals/year be instituted to include all fish taken from Ponds 1 through 5, until pertinent data are available. This amounts to a lifetime limit of 133 meals applied to fish caught from any of these ponds.
It is not known whether fish and shellfish in immediately adjacent areas of Patuxent River and Chesapeake Bay might pose a health hazard. Limited data exist for possible contaminants in surface water, sediment, and biota in areas of the Patuxent River and Chesapeake Bay (including the seaplane basins) potentially impacted by on-base sites. Three such sites of interest are Fishing Point Landfill, the Fuel Farm, and the DRMO Yard. ATSDR recommends sampling sediment and shellfish or other edible benthic fauna from areas of the bay adjacent to potential on-site sources of contaminants. Sediment analysis would be an indicator of possible contamination migration from the installation, establishing whether contaminants corresponding to those found on base were detected in the immediately adjacent estuarial sediments at concentrations significantly higher than "background" values seen in federal, state, and other aquatic-environment databases. Shellfish results would indicate whether contaminants were likely to exist in aquatic fauna at concentrations of public health concern.
NO PUBLIC HEALTH HAZARD
ATSDR concluded that two situations on the NAS Patuxent River installation pose no public health hazard.
Future on-base well and deep aquifer contamination was evaluated and judged to pose no public health hazard so long as current prevention measures are continued. Some base wells are hydrogeologically downgradient from contaminated sites. The aged (up to 54-year-old) well casings have been evaluated to determine whether the wells and the deep aquifer they access are vulnerable to infiltration by contaminated groundwater from the shallow aquifer. ATSDR has reviewed well-monitoring data, groundwater flow, and potential for groundwater contamination. We commend NAS Patuxent River's initiative to rehabilitate or abandon and seal older wells based on a variety of criteria, including age of well; extent of proximate, upgradient groundwater contamination; results of down-well video camera inspection; and installation water requirements. We recommend the continuation of these practices to ensure the integrity of the wells and thereby the purity of the drinking water and the deep aquifers. This proactive approach is preferable to periodic analysis of well-water quality designed to detect analytes present in nearby shallow groundwater, such as petroleum compounds near a site with past or present leaks from underground fuel tanks. The chemical monitoring approach requires that measurable contamination enter the water supply before detection occurs and remediation can begin.
On-site physical hazards and verified or suspected surface contamination associated with the 46 sites pose no public health hazard. Contamination may be present on installation sites from past disposal practices, but conditions exist that make it unlikely people would be exposed to these contaminants. Approach to many of the sites is effectively restricted by lack of access; fences; capping of the site; or posting to forbid hunting, fishing, or trespassing. Further, NAS Patuxent River has reviewed all IRP sites and posted additional signage on seven of these sites to inform and warn of potential hazards. No offsite migration of contaminants to areas where surficial exposure might occur is expected. When sites are demonstrated to harbor no significant hazards or are effectively remediated, postings for those sites may be removed.
This report is organized by exposure situations. These situations and the sites at which they occurred are listed below. The term site is used to describe a distinct area to which the installation NAS Patuxent River has assigned a reference number. Exposure situation is used to describe conditions and circumstances by which people could come in contact with contaminants.
In preparing this public health assessment, ATSDR relied on the information provided in the referenced documents. ATSDR assumes that adequate quality-assurance and quality-control measures were followed with regard to chain-of-custody, laboratory procedures, and data reporting. The validity of the analyses and conclusions drawn for this health assessment are determined by the reliability of the referenced information.
During the environmental investigations at NAS Patuxent River, base personnel identified Installation Restoration Program (IRP) sites from old documents and interviews with past and current employees. Environmental sampling was conducted at those sites where evidence suggested chemical contamination. From these data and from information gathered during our installation visit and from our visual inspections, we identified a number of sites that suggested the possibility of human exposure. The Figure shows the location of the 46 current IRP sites, and identifies the sites by name. Potential exposures associated with certain of these sites fall into the following situational categories:
These possible exposure situations are summarized in Table 1 and discussed in the body of the report. A fourth situation, possible future contamination of deep aquifers, and a fifth, physical dangers and/or verified or suspected surface contamination on installation restoration program (IRP) sites, represent no public health hazard.
A. Site Description, History, and Demographics
Naval Air Station Patuxent River is an active 6,800-acre installation on Cedar Point Peninsula in St. Mary's County, Maryland, 65 miles southeast of Washington D.C. The base was commissioned on April 1, 1943 and is located at the confluence of the Patuxent River and Chesapeake Bay.
The mission of NAS Patuxent River is to maintain and operate facilities and provide services and materials to support operations of the Naval Air Warfare Center, Aircraft Division (NAWCAD) and other activities and units as designated by appropriate authority. The NAWCAD is a research, development, test and evaluation (RDT&E), engineering, and support center of air platforms (1).
In February 1997, NAS Patuxent River reported a population that comprised approximately 2,450 military personnel, 4,700 Department of Defense civilian employees, 6,250 contractors and nonappropriated fund employees, and 2,500 military dependents (2).
The census tract that includes the unincorporated community of Lexington Park is adjacent to the western edge of the base and contained about 10,000 persons in 1990. This tract contained 74.1% whites and 21.5% blacks in 1990; 3.2% of persons were of Hispanic origin, and 51.8% were male. Approximately 23% of the 1990 population was under age 10, with about 2.9% age 65 and over. The median frequency of change of domicile for heads of household in this tract was 2.1 years. The corresponding frequency for the adjacent census tract that encloses NAS Patuxent River was 5.0 years. Population densities for the two tracts were between 300 and 400 persons per square mile (3).
St Mary's County had a 1990 population of approximately 76,000 persons. Whites constituted 84.4% of the county's population; blacks, 13.5%; Hispanics, 1.6%; and 50.1% was male. About 17.1% of persons were under age 10 years and 8.3%, over 65 years. The median length of time that householders had been in their current household was 5.4 years. Population density was 210 persons per square mile (3).
Past waste disposal and storage practices at NAS Patuxent River have resulted in environmental contamination at multiple sites. Environmental investigations at the base have been conducted under the Department of the Navy Assessment and Control of Installation Pollutants (NACIP) Program, the Installation Restoration Program (IRP), and the Underground Storage Tank Program, among others. NAS Patuxent River personnel have taken numerous actions to remediate the areas of contamination on the station and to mitigate contaminant migration. A detailed discussion of IRP data and actions is provided in the station's IRP documents at the station library and at the Lexington Park Public Library.
B. ATSDR Involvement
NAS Patuxent River was placed on the Environmental Protection Agency's (EPA) National Priorities List (NPL) in June 1994. The NPL, also known as the Superfund List, is a list of hazardous waste sites slated for cleanup. The Agency for Toxic Substances and Disease Registry (ATSDR) is mandated to conduct a public health assessment at each site proposed for or listed on the NPL.
ATSDR identifies ways in which people have been, are, or could be exposed to contaminants at
an installation and, if such exposure situations are identified, determines whether they represent
public health hazards. Determinations described below were arrived at based on observations
made during a September 1995 installation tour that included a review of environmental data and
discussions with officials of NAS Patuxent River, the Maryland Department of the Environment,
and the U.S. Environmental Protection Agency. ATSDR staff returned to NAS Patuxent River in
November 1996 to revisit selected sites and discuss issues raised subsequent to the August 1996
release of the Public Comment issuance of the Public Health Assessment.
