PUBLIC HEALTH ASSESSMENT
DOVER AIR FORCE BASE
DOVER, KENT COUNTY, DELAWARE
Throughout the PHA process, ATSDR has gathered information about health concerns. Most of these concerns were identified during the ATSDR scoping site visits in 1991 and 1998; through meetings with state, local, and USAF officials; and review of site documents, including DAFB's Community Relations Plan (CRP). The CRP provides guidance for involving the community and other interested parties in the remediation decision-making process and for distributing information to these parties. The USAF interviewed community members who are or potentially are affected by contamination at DAFB while preparing the CRP.
No specific health concerns have been brought to ATSDR's attention, although general concerns about potential health hazards associated with the site and off-site migration of contaminants are identified in the CRP. ATSDR addresses these concerns in the "Evaluation of Environmental Contamination and Potential Exposure Pathways" section of this PHA.
ATSDR recognizes that the unique vulnerabilities of infants and children demand special emphasis in communities faced with contamination of their water, soil, air, or food. Children are at greater risk than adults from certain exposures to hazardous substances emitted from waste sites and from emergency events involving hazardous chemicals. In general, children are more likely to be exposed because they play outdoors, have more hand-to-mouth behavior, and often bring food into contaminated areas. They are shorter than adults, which means they breathe dust, soil, and heavy vapors that are close to the ground. Children are also smaller, so they receive higher doses of chemical exposure proportional to their body weight. The developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. Most importantly, children depend completely on adults for risk identification and management decisions, housing decisions, and access to medical care.
ATSDR has attempted to identify populations of children at DAFB. There are two elementary schools and one middle school at DAFB. These schools serve the children of military personnel who live in Eagle Heights or Eagle Meadows Housing Annex. The installation also has a child development center that offers regular childcare services during the week.
Following a careful evaluation of possible exposure situations for children at DAFB IRP sites, ATSDR determined that it is unlikely that harmful exposures or physical risks have occurred in the past, occur now, or will occur in the future. Although contaminants have been detected at DAFB, children cannot access IRP sites or other potential areas of concern.
Like other people living at or near DAFB, children might contact contaminants in non-IRP areas or be at risk from physical hazards. As discussed in the "Evaluation of Environmental Contamination and Potential Exposure Pathways" section, possible exposures to children include past use of groundwater at Gooch Trailer Park, ingestion of arsenic from the base drinking water supply, or inhalation of vapors in Eagle Heights homes above the groundwater plume. ATSDR evaluated these situations and estimated the potential exposure doses for children. To date, no known cases of childhood illness related to site contamination or noted exposure situations have been reported.
In addition to the previously mentioned exposure pathways, ATSDR identified two additional potential exposure situations for children. These are described below:
- Incidental ingestion of lead-based paint. Lead-based paint was used in base residences before 1978. Certain children living in base housing might be at greater risk of experiencing lead-related health effects, depending on factors that influence exposure (e.g., age of children at exposure, play habits, presence and condition of lead-based paint in homes, and concurrent lead exposures). ATSDR recommends that children be kept away from paint-chipped surfaces and that residents contact the Family Maintenance Office with concerns about severely chipped surfaces. Children should be assessed for lead exposure at the 12-month well baby visit under the state of Delaware's program universal blood lead screening program. Parents who are concerned about their child's exposure to lead should discuss this with their child's health care provider.
- Contact with material or landfill gas near a former landfill. Land above landfill LF26 is currently used for three ball fields and is located near the Welch Elementary and Middle School. The 2-acre landfill was used for disposal of general refuse and construction debris in the 1950s and 1960s. Field investigations indicated low levels of contaminants warranting no further action. DAFB has since covered the landfill with soil and grass, which further limits contact hazards, and soil gases are most likely no longer created or emitted. DAFB spreads and grades clean soil on the ball fields each year as part of its general grounds-maintenance. This measure helps ensure that an adequate layer of soil covers the landfill and thus further limits the potential for children to come in contact with the contents of the underlying landfill.
Conclusions regarding potential past, current, and future exposure situations on and in the communities near DAFB are based on a thorough evaluation of site investigation data and observations made during site visits. Conclusions about exposures are described below. (The public health hazard conclusion categories are described in the glossary.)
- Contaminants have leached into the groundwater beneath DAFB. No exposure to these contaminants has occurred via the DAFB drinking water supply because the drinking water wells are not in the same aquifers as the contaminant plumes. In addition, institutional controls prevent the use of the contaminated aquifer for drinking water. Currently, the DAFB water supplier routinely tests its water to ensure that it meets state and federal safe drinking water standards. In the past, currently, and in the future there is no public health hazard from site-related contaminants in on-base drinking water.
- VOCs were detected in a private drinking water well used by Gooch Trailer Park and wells supplying a few other neighboring off-base properties. The VOCs, however, were not at levels that would be expected to cause illness or health effects for people who drank water from the well or used the water for other domestic purposes in the past. This past exposure, therefore, posed no apparent public health hazard. DAFB has supplied the park with an alternate water supply since 1984 and is currently pursuing plans to connect the park to a water utility service. No exposures are currently occurring nor will occur in the future.
- Certain housing units at DAFB contain lead-based paint. Base residents are informed about the potential hazards of lead when they first move into base housing and DAFB is removing lead hazards from residential units as they are vacated. Children living at the base are scheduled for blood lead testing in accordance with the state of Delaware universal lead screening program. To date, no cases of childhood blood lead poisoning associated with base housing have been confirmed at that base. As long as people take recommended precautions to prevent lead exposure, no apparent public health hazard exists.
- Some housing units in the Eagle Heights Housing Area sit above a VOC-contaminated groundwater plume in the shallow Columbia Aquifer that has migrated from the main portion of the base. Because VOCs in groundwater can travel thru the soil into overlying buildings, ATSDR conducted health-protective indoor air modeling based on maximum groundwater concentrations. The results showed that VOC contaminants could be present in the air inside certain buildings, but the estimated levels are below those associated with adverse health effects. In addition, groundwater contamination in the housing area is expected to decrease as a result of DAFB's ongoing remedial efforts, further reducing the risk of future indoor air contamination. Therefore, no apparent public health hazards associated with indoor air have occurred, nor are they expected to occur in the future.
- Three ball fields sit above the former Landfill D-11 (LF26) and a school is located nearby. This 2-acre landfill was used for disposal of construction rubble and general refuse in the 1950s and 1960s. Field investigations indicated low levels of contaminants warranting no further action. A layer of soil and grass added to the landfill after its closure prevents direct contact with landfill material, and landfill gases are likely no longer emitted. No public health hazards from landfill material are associated with use of the ball fields or school.
EPA recently lowered its standard for arsenic in drinking water from 50 ppb to 10 ppb. Arsenicwhich is most likely from natural depositshas been detected above 10 ppb in a DAFB drinking water supply well. Limited available sampling shows that the arsenic concentrations in the distribution system water have been below 10 ppb and these levels are not expected to pose harm to individuals who rely on the base water supply. In order to meet EPA's new standard, however, DAFB plans to either stop using the two Piney Point wells for drinking water or abandon the wells in late 2003. Therefore, no apparent public health hazards associated with arsenic in groundwater are expected for people receiving their drinking water from the DAFB water supply.
ATSDR also assessed the exposure to VOCs moving from the water to the air during showering. Using a protective screening model, ATSDR predicted air concentrations based on the highest levels of VOCs found in the water. ATSDR also assumed that all of the VOCs volatilized to air and that no dissipation occurred. Using these assumptions, ATSDR concluded that, in the past, VOCs would not have reached levels in indoor air that would cause adverse health effects and, therefore, posed no apparent public health hazard.
- ATSDR recommends that children be kept away from chipped paint surfaces to prevent exposure to lead-based paint and that residents contact the Family Maintenance Office with concerns about severely chipped surfaces. ATSDR concurs with DAFB's and Delaware's lead exposure assessment and screening programs. Parents who are concerned about their child's exposure to lead should discuss this with their child's health care provider.
- Although VOC-contaminated groundwater is located beneath the Eagle Heights Housing Area, concentrations are expected to decrease as a result of DAFB's ongoing remedial efforts. If, however, monitoring indicates that VOCs in groundwater are not decreasing, ATSDR recommends that DAFB consider indoor air sampling in buildings above the plume.
The public health action plan (PHAP) for Dover Air Force Base contains a description of actions taken or to be taken by DAFB, ATSDR, EPA, and DNREC at and in the vicinity of the site subsequent to the completion of this PHA. The purpose of the PHAP is to ensure that this PHA not only identifies potential and ongoing public health hazards, but also provides a plan of action designed to mitigate and prevent adverse human health effects resulting from exposure to hazardous substances in the environment. The public health actions that are completed, ongoing/planned, or recommended are as follows:
- The USAF has identified 59 IRP sites at Dover Air Force Base. DAFB has grouped the sites within four management units: the East Management Unit, the North Management Unit, the West Management Unit, and the South Management Unit. DAFB has also investigated nine areas of groundwater plumes (Areas 1 through 9) associated with multiple sources.
- The USAF has undertaken measures to reduce the sources of contamination at DAFB. These measures include removal of soil from a landfill (LF18) in the South Management Unit in 1996; excavation of buried drums from at a fire training area (FT01) in the East Management Unit; removal of concrete basin and soils from WP21 in the West Management Unit in 1999; and removal of O/W separator systems at several locations throughout the base. The USAF has also initiated natural attenuation or accelerated anaerobic bioremediation at several Areas where VOCs have contaminated the groundwater.
- The USAF has recommended 33 IRP sites for no further action because they pose no risk to human health (31 IRP sites) or they have been remediated to cleanup standards (2 IRP sites) (USAF 2003).
- The USAF has provided an alternate water supply to the residents of Gooch Trailer Park after VOC contaminants were detected in the park's only drinking water well.
- ATSDR visited DAFB in 1991 to tour the site, meet with site representatives, and gather environmental and exposure information to complete the public health evaluation. ATSDR visited the site again in February 2003.
Ongoing and Planned Actions
- Ten sites are currently undergoing actions to mitigate groundwater pollution through monitored natural attenuation of chlorinated solvents or fuel-related products, systems to recover free-phase jet fuel, or accelerated anaerobic bioremediation (USAF 2003).
- USAF is awaiting state and EPA concurrence on feasibility studies for the West and South Management Units, and signing of Records of Decision for the remaining four groundwater plumes (encompassing 16 sites) that require further remediation.
- DAFB continues to provide residents of the Gooch Trailer Park with alternate drinking water. Construction work to connect the Gooch Trailer Park, the P & F Motorcycles business, and a residence to Tidewater Municipal Water Service began on September 2, 2003, and is expected to be completed in mid-October.
- In an effort to prevent lead poisoning hazards at DAFB:
- DAFB will continue to remediate or demolish certain base housing units, some of which contain lead-based paint.
- The on-base medical clinic continues to screen children at their 12-month well baby visits, as well as children not previously screened, children at high risk of lead exposure, and children with blood lead levels above 10 µg/dL.
- The Housing Division informs prospective residents about lead hazards in their homes and ways to prevent exposure.
This report was prepared by the following individuals:
Aimee Tucker Treffiletti
Environmental Health Scientist
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
Gary Campbell, Ph.D.
Environmental Health Scientist
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
Assistance in the preparation of this report was provided by:
ATSDR Regional Representative
ATSDR Regional Office (Region 3)
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
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