PUBLIC HEALTH ASSESSMENT
ANDREWS AIR FORCE BASE
CAMP SPRINGS, PRINCE GEORGE'S COUNTY, MARYLAND
Andrews Air Force Base (AFB) is located in Prince George's County, Maryland, about 5 miles southeast of Washington, D.C. The main base is approximately 4,300 acres with an additional 2,511 acresin remote facilities (Brandywine Defense Reutilization and Marketing Office, Brandywine Receiver Site, and Davidsonville Transmitter Station). Divisions of the Air Force, Army, Navy, and Marine Corp reside at the base. Pilot training and air defense for the District of Columbia have been the basic primary missions. Andrews AFB is also home to Air Force One, the President's fleet of planes.
Remediation at Andrews AFB began in 1985 under the Installation Restoration Program (IRP). The 89th Airlift Wing is the agency responsible for conducting investigations and remedial activities at Andrews AFB. The Maryland Department of the Environment, Prince George's County Health Department (PGCHD), and more recently the U.S. Environmental Protection Agency (EPA) have provided oversight and involvement in the IRP process. Since 1985, 32 sites under the IRP and 78 solid waste management units have been identified that require investigation and/or potential remediation. Andrews AFB was placed on EPA's National Priorities List in May 1999, primarily for contamination in the Piscataway Creek watershed.
Principal site contaminants are the result of past routine operations (e.g., the use of toxic materials for aircraft operations and maintenance, fire training, civil engineering, vehicle maintenance, and dry cleaning) and accidental spills, including chlorinated solvent and petroleum releases. Most of the contamination is contained on Andrews AFB property, however, some contamination has migrated off base via the groundwater and surface water pathways.
The Agency for Toxic Substances and Disease Registry (ATSDR) visited Andrews AFB in January 2000 and met with base, EPA, and PGCHD personnel. During its review of available information, ATSDR identified the ways that people might be exposed to environmental contamination. ATSDR prepared this public health assessment to evaluate exposure pathways and to respond to community concerns about past, current, and potential future exposures to environmental contaminants originating from Andrews AFB. The exposure pathways discussed in this public health assessment were chosen based on: evaluations made during the site visits, an examination of environmental data, and concerns raised by involved parties (i.e., regulators, community, and the Air Force environmental program). Based on a thorough review of the available data, ATSDR has reached the following conclusions.
Surface Soil Pathway. Surface soil at Andrews AFB is contaminated as a result of various site activities, such as landfilling and fire training. Access by the general public to Andrews AFB is restricted. In addition, some of the contaminated areas are fenced. ATSDR focused its evaluation on those areas that are frequently accessed by residents or visitors of the base. Surface soil surrounding two sandblasted water towers had elevated lead concentrations in the past. Brook's AFB's Institute for ESOH (Environmental Safety and Occupational Health) Risk Analysis and Andrews AFB's Bioenvironmental Engineering Flight jointly, and in consultation with ATSDR sampled the soil for residual lead contamination to help determine whether a current health hazard could exist in those areas. After reviewing the data, ATSDR does not expect that exposure to soil surrounding water tower No. 3589 poses a health hazard because the levels of lead, cadmium, and chromium were too low to be of health concern. Further evaluations are underway at water tower No. 4614 to further define the extent of lead contamination in soil. Preliminary results suggest an extremely limited extent of contamination. Surface soil at the Family Housing Units, former soccer fields, southern golf course, and off-site flightline area did not, are not, and are not anticipated in the future to pose a health hazard to people living and/or recreating in those areas because contaminant levels were too low to be of health concern.
Surface Water and Sediment Pathway. Surface water that originates on Andrews AFB flows via a network of rivers and creeks into either the Patuxent or Potomac Rivers. Many of these surface water bodies are used for recreation downstream from Andrews AFB. ATSDR evaluated the potential exposure to people, including children, who may recreate and/or play in the on-site and off-site portions of the rivers and creeks. Samples of on-site and off-site surface water and sediment from an unnamed tributary to Paynes Branch, Cabin Branch, the Base Lake, Piscataway Creek, Henson Creek, and Charles Branch do not contain contaminants at levels of health concern for people who use these waterways for recreation.
Groundwater Pathway. Andrews AFB does have contaminated groundwater. However, water beneath the site is not used for drinking. Only those plumes that are migrating off base have the potential to impact drinking water wells outside of Andrews AFB. Of the nine defined plumes, only the plume originating from a former landfill, LF-05, has migrated off base. At this time, it does not appear that contaminated groundwater is adversely impacting private drinking water wells downgradient from LF-05. Of the two identified wells, one has been tested and no site related chemicals were detected. The other well is currently closed. To confirm that no exposures are occurring, ATSDR recommends that PGCHD survey the area to confirm that no unidentified shallow groundwater wells are being used. If wells are found to be in use, PGCHD should inform the residents of the potential for contamination and Andrews AFB should offer to test the water from these wells to ensure the water is safe to drink.In August 2000, a groundwater seep from Foxley Road was noticed, which lead to PGCHD collecting and analyzing surface water and sediment samples. While the level of chlorobenzene was higher than levels found in the off-site monitoring wells, the concentration was too low to be of health concern for children who might have incidental contact with the seep if playing in the area and construction workers who may have contact during proposed road construction on Foxley Road.
At a remote facility, Davidsonville Transmitter Station (SS-11), residents and employees rely on groundwater wells as their drinking water source. In 1984, heating oil was released into the environment from a leaking underground storage tank. Not enough information exists to rule out the potential for extensive groundwater contamination at this site. ATSDR recommends that Andrews AFB sample and analyze water from the existing monitoring wells at Davidsonville Transmitter Station to confirm the presence or absence of groundwater contamination at the site.
Soil Gas Pathway. Because contaminated groundwater is located on base, the potential exists for volatile organic compounds to enter buildings located above the groundwater plumes. However, after evaluation, ATSDR determined that the concentrations of volatile organic compounds detected in the groundwater and soil gas underneath occupied buildings were too low to be of health concern.
Andrews Air Force Base (AFB) is located about 5 miles southeast of Washington, DC, in Prince George's County, Maryland, approximately 25 miles southwest of Annapolis, Maryland, and 40 miles south of Baltimore, Maryland (see Figure 1). The main base is approximately 4,300 acres, but remote facilities encompass an additional 2,511 acres: Brandywine Defense Reutilization and Marketing Office (8 acres), Brandywine Receiver Site (1,640 acres), and Davidsonville Transmitter Site (863 acres) [Andrews AFB 1999a]. Andrews AFB consists of runways and airfield operations, 81 miles of road, 60 tenant units, recreational facilities, and 780 acres of unimproved land (i.e., open fields and wood lots with grasses, shrubs and mature trees). In addition to Air Force commands, divisions of the Army, Navy, and Marine Corps also reside at Andrews AFB.
The area surrounding Andrews AFB is residential, commercial/industrial, agricultural, and wooded. Strip malls interspersed with small communities are on several sides of the base. The three closest towns are: Morningside to the northwest, Camp Springs to the west, and Clinton to the south. Major highways and arteries border Andrews AFB on all sides.
The soils under Andrews AFB consist of a gravel, sand, and silt top layer about 50 feet thick; underlain by clayey silt, silty clay, sand, and rock. Andrews AFB sits atop two drainage basins: Potomac River Basin and Patuxent River Basin. Surface water runoff to the northwest, west, and south flows into Henson Creek, Meetinghouse Branch, Paynes Branch, and Piscataway Creek and eventually into the Potomac River. Surface drainage from the north and east flows into the Patuxent River via Cabin Branch and Charles Branch. Groundwater found in the upland deposits is shallow, at depths of 20 feet or less below grade. The movement of this shallow groundwater is generally toward local surface waters. Several deep aquifers exist under Andrews AFB and the surrounding Prince George's, Anne Arundel, and Charles Counties.
Principal site contaminants are believed to be the result of routine operations (e.g., flightline, landfilling, and fire training activities) and accidental spills, including chlorinated solvent and petroleum releases. Most of the contamination is contained on Andrews AFB property, though some contamination has migrated off base via groundwater and surface water.
Brandywine Defense Reutilization and Marketing Office is a remote facility that is a separate National Priorities List site, with unique community concerns and different environmental issues than Andrews AFB. Different populations of people are potentially impacted, as well. For these reasons, ATSDR addressed environmental exposure at Brandywine Defense Reutilization and Marketing Office in a separate public health assessment (ATSDR 2001).
Andrews AFB was officially established August 25, 1942, as Camp Springs Army Air Field (Andrews AFB 1997; Andrews AFB 1999a). The name was changed to Andrews AFB in 1947 when the Air Force became a separate military unit. Andrews AFB is the largest employer in Prince George's County with approximately 17,000 military and civilian employees (Andrews AFB 1999a). Pilot training and air defense of the District of Columbia have been its primary missions. Andrews AFB has been the headquarters base for the Continental Air Command, Strategic Air Command, the Military Air Transport Service, and Air Force Systems Command. Andrews AFB is also home to Air Force One, which consists of two Boeing 747s that have special accommodations for the President of the United States. In addition to the President and Vice President, Andrews AFB provides worldwide airlift for foreign heads of state, cabinet members, and other dignitaries who travel to Washington, DC.
The 89th Airlift Wing is the agency responsible for remediation at Andrews AFB. Under the Department of Defense's Installation Restoration Program (IRP), the 89th Airlift Wing has been conducting investigations and remedial activities at Andrews AFB. The Maryland Department of the Environment (MDE) and the Prince George's County Health Department (PGCHD) have provided ongoing oversight and involvement in the IRP process. MDE, Oil Control oversees remediation at sites with fuel contamination. In May 1999, The U.S. Environmental Protection Agency (EPA) placed Andrews AFB on the National Priorities List, primarily for contamination in the Piscataway Creek watershed. With the exception of Brandywine Defense Reutilization and Marketing Office, the remote facilities were not listed on EPA's National Priorities List; however, they are part of the IRP and are therefore, discussed briefly in this public health assessment.
Throughout operations at Andrews AFB the use of toxic materials for aircraft operations and maintenance, fire training, civil engineering, vehicle maintenance, and dry cleaning generated waste products. In 1985, investigations were begun to identify potential hazardous waste sites, confirm the presence or absence of contamination, examine potential cleanup alternatives, and implement the chosen remedies.
To date, 32 sites have been identified through the IRP that require investigation and/or potential remediation (Andrews AFB 1999a). Ten of the sites are Areas of Concern (AOC) where contamination is suspected, but not confirmed. After being identified, AOC-28 was determined to not contain contaminants and was dropped from further investigation. For three sites (ST-09, ST-15, and AOC-23), no further remedial action is planned in accordance with their respective decision documents. SS-12 was recently closed by MDE because the site was in compliance with the Code of Maryland Regulations. Investigations to identify the nature and extent of contamination, determine the potential effects on public health and environment, and evaluate potential action alternatives are underway at eight sites (SS-01, FT-02, FT-03, LF-05, ST-10, SS-11, ST-14, and SS-21), remedial actions to implement the chosen control and/or cleanup measures are being conducted at five sites (SS-13, ST-17, ST-18, ST-19, and ST-20), and interim remedial actions are underway at three sites (FT-04, ST-08, and SS-22). Remedial Investigations are planned for another three sites (LF-06, LF-07, and WP-16).
In June and December 2000, EPA, MDE, PGCHD, and Andrews AFB identified 78 solid waste management units (SWMUs) at the base that require historical research, current investigation, and/or potential remediation (PGCHD 2001). Several of the SWMUs overlap with the IRP sites already identified. Many are waste accumulation points that may or may not have contributed to environmental contamination; no leaks or spills have been identified. Other SWMUs were identified as incinerators, sewage treatment plants, water towers, laboratories, underground storage tanks (USTs), aboveground storage tanks (ASTs), and storage buildings/areas.
As part of the public health assessment process, the Agency for Toxic Substances and Disease Registry (ATSDR) conducted an initial scoping visit and met with Andrews AFB officials from the Safety, Public Affairs, Public Health, and Bioenvironmental Engineering Departments; EPA; and PGCHD on January 18-21, 2000. ATSDR gathered information regarding potential pathways of human exposure to contaminants. From these meetings and a review of the data then available, ATSDR determined that no immediate threats to public health existed, but that several potential exposure pathways and community health concerns required further evaluation.
The following community concerns were identified and addressed in this public health assessment:
- PGCHD was concerned that children and construction workers may contact contaminated groundwater seeping from Foxley Road.
- During the initial site visit, ATSDR noticed two buildings were located over a contaminated groundwater plume at ST-14. ATSDR was concerned about the potential accumulation of soil gases in the buildings.
- A former Andrews AFB employee was concerned that two instances of leukemia were linked to a TCE plume located in the groundwater beneath a trailer where the employees worked.
- Community members who live near the Petroleum, Oils, and Lubricants (POL) Storage Yard (SS-13) were concerned about groundwater contamination at the site impacting their health.
- A resident of Andrews AFB inquired about the potential for lead-based paints in his home. He noticed that the paint was peeling and was concerned because he has a young child who might be exposed to lead from this source.
- Community members expressed concerns to PGCHD about the contaminant plumes originating from Andrews AFB. They wanted to know the location of the groundwater plumes.
- Community members also expressed specific concerns to PGCHD about the impact Andrews AFB is having on Piscataway Creek.
ATSDR examines demographic information (i.e., population information) to identify the presence of sensitive populations, such as young children and the elderly, in the vicinity of a site. Demographics also provide details on residential history in a particular area--information that helps ATSDR assess time frames of potential human exposure to contaminants. Demographic and land use information for the residential areas surrounding Andrews AFB is presented in this section.
Andrews AFB is located near Camp Springs in Prince George's County, Maryland. The U.S. Bureau of the Census 1997 Population Estimates found that 780,541 people resided in Prince George's County. About 56.2% are African-American, 37.6% are white, 4.6% are Asian or Pacific Islander, 1.3% are Other, and 0.3% are American Indian. Within Prince George's County are 115 elementary schools, nine middle schools, 47 secondary schools, 102 private schools, and three higher education schools (Andrews AFB 1999a).
According to the 1990 U.S. Bureau of the Census, 41,568 people live within the census block surrounding Andrews AFB. About 48.5% are white, 47.6% are African-American, 2.7% are Asian or Pacific Islander, 0.7% are Other, and 0.5% are American Indian. Andrews AFB estimates that approximately 6,670 people (including officers, enlisted men and women, and dependants) currently live on the base. According to the 1990 U.S. Bureau of the Census the average income for people living on Andrews AFB was $30,972. The median income for the surrounding area ranged from $35,229 to $60,147. In 1990, less than 3.2% of the population lived below poverty levels (Andrews AFB 1999a).
The current land use at Andrews AFB is a mix of five general categories: airfield, housing/recreation, industrial support, administrative services, and open space. Because of the level of existing development, future land use is expected to remain similar to the current land use (Andrews AFB 1996, 1997).
- The primary land use is for airfield operations. This includes airfield pavement, aircraft maintenance and operations, and restricted safety/environmental zones. Most of the east-central section of Andrews AFB is used for this purpose.
- The second largest land use area on base is residential housing, recreation, and service areas. Residential housing consists of single-family units, duplexes, and apartments. The majority of the housing units are located on the west side of the base, away from the airfield, with one smaller area in the northeast corner. Outdoor recreational areas include golf courses, soccer fields, ball fields, a tennis court, a running track, and picnic areas. The majority of the outdoor recreational facilities are on the southwest corner of the base. Medical services are located on the west side of the base, away from the airfield and industrial areas.
- A few industrial support areas are located east of the runways, east of Virginia Avenue, and south of San Antonio Boulevard. These areas are used for supply storage, utility systems, and maintenance facilities.
- Administrative services include the base headquarters, personnel communications, and legal support. These areas are located in the northwest section of the base, around Fetchet Avenue, at the intersection of Arnold Avenue and Menoher Drive, and east of East Perimeter Road.
- Small amounts of open space, defined as undeveloped land and surface waters, exist near the perimeter of the base and off San Antonio Boulevard. The Base Lake is also included in this category.
The area surrounding Andrews AFB to the east is residential, commercial, light and heavy industrial, agricultural and some open land. The land use to the south is residential, commercial, light industrial, and some open land. The land use to the west is residential, commercial, and industrial. The area to the north is commercial and light industrial (PGCHD 2001).
In preparing this public health assessment, ATSDR reviewed and evaluated information provided in the referenced documents. Documents prepared for the IRP program must meet specific standards for adequate quality assurance and control measures for chain-of-custody procedures, laboratory procedures, and data reporting. The environmental data presented in this public health assessment are from reports produced by the Air Force, MDE, PGCHD, and EPA.The limitations of these data have been identified in the associated reports.Based on our evaluation, ATSDR determined that the quality of environmental data available in most site-related documents for Andrews AFB is adequate to make public health decisions. Data validation was not available for some of the lead samples taken near the sandblasted water towers, nor the surface water and sediment samples taken from the seep at LF-05.
What is meant by exposure?
ATSDR's public health assessments are exposure, or contact, driven. Chemical contaminants disposed or released into the environment have the potential to cause adverse health effects. However, a release does not always result in exposure. People can only be exposed to a chemical if they come in contact with the chemical. Exposure may occur by breathing, eating, or drinking a substance containing the contaminant or by skin contact with a substance containing the contaminant. To acquaint readers with terminology used in this report, a glossary is included in Appendix A.
How does ATSDR determine which contaminants and exposure situations to evaluate?
ATSDR scientists evaluate site conditions to determine if people could have been (a past scenario), are (a current scenario), or will be (a future scenario) exposed to site-related contaminants. When evaluating exposure pathways, ATSDR identifies whether exposure to contaminated media (such as soil, water, air, or waste) has occurred, is occurring, or will occur through ingestion, dermal (skin) contact, or inhalation.
If exposure was or is possible, ATSDR scientists then consider how often exposure occurs and whether contamination is present at levels that might affect public health. ATSDR selects contaminants for further evaluation by comparing them against health-based comparison values. Comparison values are developed by ATSDR from scientific literature available on exposure and health effects. These comparison values are derived for each of the different media and reflect the estimated contaminant concentration that is not expected to cause adverse health effects for a given chemical, assuming a standard daily contact rate (e.g., amount of water or soil consumed or air breathed) and body weight.
Comparison values are not thresholds for adverse health effects. ATSDR comparison values establish contaminant concentrations many times lower than levels at which no effects were observed in experimental animals or human epidemiologic studies. If contaminant concentrations are above comparison values, ATSDR further analyzes exposure variables (for example, duration and frequency), the toxicology of the contaminant, other epidemiology studies, and the weight of evidence for health effects.
Some of the comparison values used by ATSDR scientists are described in the glossary in Appendix A and include ATSDR's environmental media evaluation guides (EMEGs), reference dose media guides (RMEGs), cancer risk evaluation guides (CREGs), and USEPA's reference doses (RfDs) and maximum contaminant levels (MCLs). MCLs are enforceable drinking water regulations, while CREGs, EMEGs, and RMEGs are non-enforceable, health-based comparison values developed by ATSDR for screening environmental contamination for further evaluation.
More information about the ATSDR evaluation process can be found in ATSDR's Public Health Assessment Guidance Manual at http://www.atsdr.cdc.gov/HAC/HAGM/ or by contacting ATSDR at 1-888-42ATSDR.
If someone is exposed, will they get sick?
Exposure does not always result in harmful health effects. The type and severity of health effects that occur in an individual from contact with a contaminant depend on the exposure concentration (how much), the frequency and/or duration of exposure (how long), the route or pathway of exposure (breathing, eating, drinking, or skin contact), and the multiplicity of exposure (combination of contaminants). Once exposure occurs, characteristics such as age, sex, nutritional status, genetics, life style, and health status of the exposed individual influence how the individual absorbs, distributes, metabolizes, and excretes the contaminant. Together, these factors and characteristics determine the health effects that may occur as a result of exposure to a contaminant in the environment.
There is considerable uncertainty about the true level of exposure to environmental contamination. To account for this uncertainty and to be protective of public health, ATSDR scientists typically use high-end, worst case exposure level estimates as the basis for determining whether adverse health effects are possible. These estimated exposure levels usually are much higher than the levels to which people are actually exposed. If the exposure levels indicate that adverse health effects are possible, then a more detailed review of exposure combined with scientific information from the toxicological and epidemiologic literature about the health effects from exposure to hazardous substances is performed.
Figure 2 provides an overview of ATSDR's exposure evaluation process.
Each source of contamination was evaluated at Andrews AFB to determine if there was a completed or potential pathway that would result in people being exposed to site-related contamination. The issues discussed in this public health assessment were chosen based on evaluations made during the site visits, an examination of environmental data, and concerns raised by the community, the Air Force, and the regulators. A list of all sources of contamination that have been identified by Andrews AFB's IRP is presented in Table 1 and graphically displayed in Figure 3. The following exposure pathways were determined to have the potential for people to contact contamination.
- Several of the IRP sites had contaminants located in the soil. However, there is no public access to the site. Therefore, exposure to contaminated soil is limited. Recreational (e.g., playgrounds, soccer fields, and golf courses) and housing (2132 Richmond Drive, Winston Drive, and Yuma Road) areas where soil contamination is present (e.g., FT-03, LF-07, AOC-27, ST-18, and the area surrounding the sandblasted water towers) were specifically evaluated because these areas are where employees, military, and their families may be exposed. Off-base soil to the south of the runways (i.e., in the flightline) was specifically evaluated for polycyclic aromatic hydrocarbons (PAHs) to determine if flightline operations were impacting soil to a harmful level.
- Several streams (e.g., Piscataway Creek, Henson Creek, and Charles Branch) originate on Andrews AFB and flow off base where they are used for recreation downstream by residents and visitors to the waterways. Additionally, the Base Lake is used for recreation by Andrews AFB employees and their families and an unnamed tributary to Paynes Branch and Cabin Branch are easily accessible to children who live on site. These waterways are potentially impacted by several IRP sites located at their headwaters (e.g., FT-03, FT-04, LF-05, LF-06, LF-07, ST-08, SS-12, SS-13, ST-14, ST-17, ST-18, ST-19, SS-21, SS-22, AOC-25, and AOC-27). These streams were evaluated because of the potential for recreational users to be exposed to the contaminants in the surface water and sediment.
- The contaminants in the groundwater pose no public health hazard at most of the IRP sites because there are no private drinking water wells near these sites and Andrews AFB receives its drinking water from Washington Suburban Sanitary Commission (WSSC). Only the plume at LF-05 has migrated off base into an industrial area where at least one private off-base well exists. The potential for groundwater contamination from a leaking underground heating oil tank exists at SS-11. Little information is available and groundwater wells are in use at and surrounding the site. Therefore, the groundwater originating from LF-05 and SS-11 was further evaluated.
- Nine IRP sites (e.g., ST-04, LF-05, ST-08, SS-13, ST-14, ST-17, ST-18, SS-21, and SS-22) have contaminated groundwater plumes. Those plumes that underlie buildings were evaluated for potential soil gas issues.
This public health assessment only discusses those pathways at Andrews AFB that lead to human exposure. Table 2 outlines these exposure pathways. Exposure to contamination in on-site and off-site surface soil, on-site and off-site surface water and sediment, off-site groundwater, and on-site soil gas are the identified pathways. These pathways were selected for discussion in this public health assessment because people have the potential to be exposed to the contamination from the listed sources (e.g., FT-03, ST-04, LF-05, LF-06, LF-07, ST-08, SS-11, SS-12, SS-13, ST-14, ST-17, ST-18, ST-19, SS-21, SS-22, AOC-25, AOC-27, and lead-based paints on water towers). People are not being exposed to contaminants from the remaining sources listed in Table 1.
The following sections discuss potential human exposure through contaminated surface soil, surface water and sediment, groundwater, and soil gas. The following questions are addressed in this public health assessment:
- Is surface soil contaminated to levels that would result in adverse health effects to people coming in contact with the soil?
- Have the surface waters and sediments been contaminated to levels that might be harmful to recreational users?
- Has contaminated groundwater migrated to nearby drinking water wells? If so, has that contamination resulted in adverse human health effects?
- Are people who occupy buildings above groundwater plumes being exposed to harmful levels of contaminants through soil gas migration?
Each section states the concern, a brief summary of ATSDR's conclusions, and a detailed discussion of the basis for the conclusions. The conclusions are based on the evaluation of data from documents provided by the Air Force, MDE, PGCHD, and EPA. For reference, Appendix A is a glossary of environmental and health terms and Appendix B summarizes the methods and assumptions used when estimating human exposure doses and determining health effects for the following pathways.
- Pathway: Surface Soil
Is surface soil contaminated to levels that would result in adverse health effects to people coming in contact with the soil?
On-Site Surface Soil
- Children living or playing near the lead-painted water towers during the sandblasting in 1990/1991 could have been exposed to levels of lead that could cause adverse health effects. One child experienced an elevated blood lead level during her exposure. Recent sampling confirmed that current levels of lead, cadmium, and chromium detected in the soil surrounding water tower No. 3589 are not at concentrations of health concern. Further investigations to determine the extent of lead contamination are ongoing at water tower No. 4614.
- Residents living in the Family Housing Units at 2131 Richmond Drive were not exposed, via incidental ingestion or dermal exposure, to harmful levels of surface soil contamination that resulted from overfilling a UST in 1991.
- People playing on the soccer fields were not exposed to harmful levels of surface soil contamination because the area was regraded and covered with soil after fire training activities.
- Golfers and maintenance crews of the southern golf course are not expected to be exposed to harmful levels of contamination in surface soil. The landfill and fire training area were partially regraded prior to the construction of the golf course and the amount of time spent in areas not regraded is minimal. Exposure to harmful levels of contamination is not expected to occur.
Off-Site Surface Soil
- The levels of PAHs detected in the off-base portion of the flightline were too low to be of health concern; therefore, runway operations are not affecting off-base soil to a harmful level.
Soils and Geology
The surficial soils at Andrews AFB are fine-grained, silty, loamy, and clayey. Under the soils, are about 50 feet of fluvial (i.e., formed by a river or stream) sediments of unconsolidated sands, silts, and clays. Under these sediments are 90 to 100 feet of clayey silts, followed by various formations of sedimentary deposits that extend for about 1,300 feet to crystalline basement rocks (Dames & Moore 1992; EA Engineering 1995a; Tetra Tech 1996).
The current land use at Andrews AFB includes: open space (undeveloped land and surface waters), direct mission areas (airfield pavement, aircraft operations and maintenance, and restricted safety/environmental zones), industrial support areas (jet fuel storage, vehicle maintenance, fire training areas, etc), housing and recreation areas (dorms, dining halls, clinics, etc.), and administrative services area (base headquarters, personnel communications, and legal support) [Andrews AFB 1997]. Future land use will remain relatively the same as the current land use.
On-Site Surface Soil
Surface soil at Andrews AFB is contaminated as a result of various site activities, such as landfilling and fire training. Some of the contaminated areas are fenced and access is restricted. ATSDR focused its evaluation on those areas that are frequently accessed by resident or visitors of the base. This section discusses the use and exposure of the following: two areas surrounding water towers that were sandblasted in 1990/1991, the Family Housing Units at 2132 Richmond Drive, the soccer fields, and the southern golf course.
Potential exposure of children to lead contamination surrounding two water towers
Nature and Extent of Contamination. During the winter of 1990/1991, two water towers (Nos. 3589 and 4614) coated with lead-based paint (23.09% and 20.42% lead paint, respectively) were sandblasted during maintenance activities (Penniman & Browne 1990). Water tower No. 3589 is located on the base boundary on Winston Drive just south of Fetchet Avenue, adjacent to a former trailer park for military personnel and their families, which was closed in December 1999. Water tower No. 4614 is located on the corner of Yuma and Perimeter Roads in a residential area with permanent brick housing units. A playground and basketball court are located within 50 feet of the water tower and a youth center is directly across the street. Both water towers are enclosed in a fence.
PGCHD inspected the sites in December 1990 and took samples at the request of a resident concerned about lead exposure from the sandblasting event. The inspectors noted visible debris and dust present in and around several housing units near both water towers. The soil samples collected around water tower No. 3589 detected lead at concentrations that ranged from 18 to 567 parts per million (ppm) [State of Maryland 1990]. Soil samples provided by Andrews AFB, taken from 290 Winston Road in 1991, were within this range (i.e., 26.5 to 160 ppm) [Andrews AFB 1991]. Soil and debris samples collected outside the fence of water tower No. 4614 indicated lead levels that ranged from 1,919 to 4,480 ppm (State of Maryland 1991a).
Carpet samples taken by Andrews AFB from 290 Winston Road in 1991, contained from less than 0.4 ppm to 27.8 ppm of lead and two swipe samples contained 15 mg/swipe and 184.5 mg/swipe of lead (Andrews AFB 1991). Dust samples that were taken by PGCHD in May 1991 from another residence near water tower No. 3589 contained from 193 to 1,574 micrograms of lead per square foot (State of Maryland 1991b). A child in that residence did have an increased blood lead level of 23 micrograms per deciliter (mg/dl) in May 1991, although her blood lead level in October 1990 was only 5 mg/dl (Walter Reed 1990; Government of DC 1991a, 1991b). To ATSDR's knowledge no dust samples were taken from residences near water tower No. 4614.
Andrews AFB directed the sandblasting contractor to clean up visible debris around both water towers and increase containment measures during sandblasting activities. Health department officials continued to inspect the site during the project. Although debris samples were analyzed for lead by the toxicity characteristics leaching procedure prior to off-site disposal, to ATSDR's knowledge no soil samples were taken after the project was completed to document residual lead levels in surrounding soil.
To address ATSDR's concern that residual lead-containing dust may still be present in the soils surrounding the water towers where people may come in contact with it, Brook's AFB's Institute for ESOH (Environmental Safety and Occupational Health) Risk Analysis (IERA) jointly with Andrews AFB's Bioenvironmental Engineering Flight performed surface soil sampling for residual lead-based paint contamination in the housing and recreational areas surrounding the water towers in April 2001. The soil samples near water tower No. 3589 contained 9 ppm to 1,330 ppm of lead, 1.14 ppm to 6.78 ppm of cadmium, and 10.9 ppm to 51.2 ppm of chromium. Some of these samples were taken at the site of a new child development center on Fetchet Avenue. These samples contained 9.7 ppm to 96.3 ppm of lead, 1.48 ppm to 2.06 ppm of cadmium, and 14.3 ppm to 20.5 ppm of chromium. The soil samples surrounding water tower No. 4614 contained 27.8 ppm to 1,260 ppm of lead, 0.72 ppm to 3.29 ppm of cadmium, and 11.5 ppm to 81.8 ppm of chromium (Andrews AFB 2001b). Further studies are underway to delineate the extent of the lead contamination where elevated levels were detected in the soil around water tower No. 4614.
Evaluation of Potential Public Health Hazards. The Centers for Disease Control and Prevention (CDC) have determined that health effects are more likely to be observed if childhood exposures are at or above 10 mg/dl. The child's blood lead level of 23 mg/dl is a level that would warrant environmental investigation and remediation. It is presumed that because the child was monitored, her physician provided any medical treatment deemed appropriate to be protective of her health. Typically, medical treatment is necessary if the lead concentration is higher than 45 mg/dl (ATSDR 1999). Although we do not have any information about other children living or playing in the areas around the water towers, ATSDR assumes other children in the area could have been similarly exposed. ATSDR does not know at what level of lead children may have been exposed. Therefore, a past public health hazard existed for children living or playing around the water towers during and shortly after the sandblasting in 1990/1991.
ATSDR evaluated the potential for current exposure to the levels of lead, cadmium, and chromium that were detected in the surface soil surrounding both water towers, including those on the grounds of the child development center. For water tower No. 3589 and the child development center the concentrations detected were too low to be of health concern; therefore, no apparent current or future public health hazards exist from exposure to the soil. Please refer to Appendix B for further details concerning how ATSDR determined health effects. Because one lead sample outside the fence at water tower No. 4614 exceeded EPA's soil screening level (SSL) of 400 ppm, Andrews AFB's Bioenvironmental Engineering Flight jointly with Brooks AFB IERA conducted follow-up sampling in May 2001 to further define the extent of contamination. The results from that investigation are not yet available. This additional sampling will determine what remedial actions are necessary to prevent people from contacting high levels of lead in the soil. Until the results are final and released to ATSDR for review an indeterminate public health hazard exists for exposure to soil near water tower No. 4614.
Potential exposure of residents to petroleum contamination
Nature and Extent of Contamination. ST-18 (UST leak) is located at 2132 Richmond Drive within the Family Housing Units at the intersection of Richmond Drive and San Antonio Boulevard. This site was investigated in 1991 because residents of the Military Family Housing Complex noticed stained soil at the site. The surficial contamination was probably the result of the 1,000-gallon heating oil UST being overfilled. During investigations, it was found that the UST was leaking. The UST had been in operation since 1972, and it is not known when the leaking began. In 1992, the leaking UST was removed and replaced with another UST and an active free product removal system was installed to eliminate the petroleum contamination (EA Engineering 1993). In 1993, the replacement UST was removed and in 1994, the active recovery system was replaced with a passive bailing system because of the lack of free-phase product being removed from the soil (IT Corporation 1996a).
In 1992, surface soil from the front and back yards of the housing units was analyzed for volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), and total petroleum hydrocarbons (TPH). Two VOCs, seven SVOCs, and TPH were detected (Table 3) [EA Engineering 1993].
Evaluation of Potential Public Health Hazards. Contaminated surface soils were removed from the Family Housing Units when the initial and replacement USTs were removed in 1992 and 1993, respectively. In addition, renovation of these housing units was underway in January 2001, and included excavation in the area of the former tanks. Any remaining contaminated soils was removed during these activities, as well. After contaminated soils are removed, no further exposures can occur. Additionally, ATSDR evaluated the potential exposure that occurred before the soils were removed and concluded that all compounds were detected at levels too low to cause adverse health effects in both children and adults. Given these two circumstances, no apparent past, current, or future public health hazard exists for residents who may have been incidentally exposed to soil in the Family Housing Units at 2131 Richmond Drive. Please refer to Appendix B for further details concerning how ATSDR determined health effects.
Potential exposure of recreational users of the soccer fields to contamination associated with former fire training activities
Nature and Extent of Contamination. Two soccer fields existed in the area of FT-03 (a former fire training area) in the southern part of Andrews AFB, south of Wheeling Road, prior to the construction of the golf course. They were in existence from sometime before 1982 through 1996. Prior to the soccer fields being created, the entire area was reportedly re-graded with fill dirt.
FT-03 consisted of a 300- to 400-foot bermed burn area and a nearby drum storage area. From 1959 to 1972, fire training activities were performed in the western corner, adjacent to the intersection of Wheeling Road and Wyoming Road. Waste oil, jet fuel, paint thinner, and other industrial liquid wastes were stored in 55-gallon drums in the northern corner (near the intersection of Wheeling and Wisconsin Roads) until they were ignited in the water-saturated bermed area. About 1,000 to 2,000 gallons of waste material were ignited during each exercise. Protein foams and chlorobromomethane were used to extinguish the fires (Ahern 1992).
No surface soil sampling has been conducted at this site. In 1988, a visual examination found no indication of surficial contamination or evidence of previous fire training activities (U.S. Department of the Interior 1989). A geophysical survey performed in 1995, noted that the general area appears to be a former dump or landfill (Tetra Tech 1996).
Evaluation of Potential Public Health Hazards. Because no surface soil sampling has been conducted at the sites of the former soccer fields, it is unknown if any contamination exists at levels of health concern. However, because the area was regraded and a top layer of fill was brought in prior to the construction of the soccer fields, minimal exposure of recreational users to contaminated soil is expected. For this reason no apparent public health hazard existed for people who played soccer on these fields. Because of the nature and extent of past activities at this site and the fact that the area is still used for recreation (i.e., as a golf course), an evaluation should be conducted to confirm that no current or future public health hazard exists. Andrews AFB is in the process of determining what remedial activities were completed prior to the installation of the soccer fields and is conducting a Remedial Investigation at FT-03 to determine the extent of any residual contaminants and identify if any risks are posed.
Potential exposure of recreational users and maintenance workers of the golf course to contamination associated with previous fire training and landfill activities
Nature and Extent of Contamination. A golf course was constructed on top of two IRP sites (FT-03 and LF-07) and one area of concern (AOC-27) in 1996.
- FT-03 is described in the nature and extent of contamination section of the discussion on the soccer fields. No surface soil sampling has been conducted at FT-03.
- LF-07 is a former 60-acre landfill that is located in the southern part of Andrews AFB, southeast of the intersection of South Perimeter Road and Wisconsin Road. The area was originally a gravel pit and was used primarily to dispose of construction rubble from the 1960s through the 1980s. Miscellaneous wastes (e.g., furniture, washing machines, metal lockers, sheet and scrap metal, household garbage, plastics, empty 55-gallon drums, waste lumber, tires, pipes, shop wastes, and hospital wastes) may also be present in the landfill. In 1994, the area was described as containing partially wooded areas, wetlands, and disturbed areas with surface debris and rubble. Average cover fill was less than 1 foot. Prior to the construction of the golf course, 20 surface soil samples were collected and analyzed for VOCs, SVOCs, pesticides, polychlorinated biphenyls (PCBs), and metals. Compounds from all categories were detected, including four VOCs, 23 SVOCs, 13 pesticides, one PCB, and 20 metals (Table 4) [EA Engineering 1995a]. A cable across the entrance restricted vehicular access however, the former landfill was not fenced off to prevent pedestrian access.
- AOC-27 is located southeast of the Base Lake near the southern boundary of the base. The area reportedly contained pits that were used for the disposal of a viscous liquid in the late 1960s to early 1970s. Soil contamination may exist due to the unknown nature of the liquid. Ongoing investigations are being conducted at AOC-27 to evaluate the extent of contamination (Tetra Tech 1996). The site was not fenced prior to the construction of the golf course.
In addition, three areas that were suspected of containing contaminants were identified and characterized during the Environmental Assessment for the construction of the golf course--a former solvent pit suspected of being located south of the Base Lake, a debris pit also suspected of containing solvents, and several areas of mounded soil piles located near the borrow pit ponds. An Andrews AFB contractor performed a soil vapor contaminant assessment at the two suspected solvent pits. Based on the results, surface (and subsurface) soil samples were taken and analyzed for chlorinated hydrocarbons, aromatic hydrocarbons, PCBs, and PAHs. The three surface soil samples that were taken from the debris pit detected PAHs in concentrations ranging from 21 parts per billion (ppb) to 3,100 ppb. Chlorinated hydrocarbons, aromatic hydrocarbons, and PCBs were not detected (EA Engineering 1995c).
Evaluation of Potential Public Health Hazards. Fill was used in the construction of the golf course to provide enough soil cover for turf grass to grow. It was recommended in the Environmental Assessment (1995) that soil from the IRP sites and AOCs not be used as a source of this fill. It is ATSDR's understanding that no intrusive excavation was performed at any of the IRP sites or areas of concern during the construction of the golf course. Sampling in the area south of the Base Lake did not seem to suggest that the area was ever used as a former solvent pit (EA Engineering 1995c) and prior to the construction of the golf course, all surface piles were removed.
In 1994, surface soil at the former landfill (LF-07) was characterized and, in 1995, surface soil samples at the debris pit were collected. All compounds detected were at concentrations well below levels expected to cause adverse health effects, in both children and adults, assuming conservative exposure scenarios. Please refer to Appendix B for further details concerning how ATSDR estimated exposure doses and determined health effects.
In addition, fill dirt was used to construct the golf course landscape and well maintained turf was planted on the green, fairway, and rough. Any surficial contamination that existed would have been covered by the fill dirt. Therefore, golfers and maintenance crews are not expected to encounter contaminants in the soil because the contaminated soil is generally not exposed. However, fill was not placed on top of the entire area and a cap was not constructed over the landfill. During ATSDR's site visit, exposed rubble was seen in one of the areas not covered by the golf course. Therefore, the areas that are not covered by the golf course remain potential contact points for exposure to contaminated surface soil. A golfer may encounter an area with exposed soil when he/she hits a ball into such an area. However, the time a golfer spends in out-of-bound areas is minimal. As part of the golf course maintenance, workers may have to maintain areas not covered with fill. However, maintenance crews are not expected to spend substantial amounts of time in the out-of-bounds areas either. The likelihood of actual contact is also minimal. Because the levels of contaminants were low and actual exposure is incidental, no apparent public health hazard exists for golfers and maintenance workers frequenting the southern golf course.
Off-Site Surface Soil
The only area where off-base surface soil has been impacted as a result of Andrews AFB operations exists south of the runways in the flightline zone. This area was contaminated with PAHs by airplanes flying in and out of Andrews AFB. PAHs are a group of chemicals formed during the incomplete burning of organic substances such as coal, wood, garbage, or in this case, oil and gas from airplanes.
Potential exposure of off-base residents to PAHs in the surface soil of the flightline
Nature and Extent of Contamination.Surface soil south of Andrews AFB was sampled for VOCs, SVOCs, PAHs, PCBs, pesticides, and metals in 1993. A total of three samples were taken--two from a strawberry field to the west of the Piscataway Creek and one from across the creek in a wooded area. No VOCs, pesticides, or PCBs were detected. Two SVOCs, 11 PAHs, and 12 metals were detected (Table 5) [Andrews AFB 1993]. The two SVOCs were also detected in the blank samples and are therefore probably laboratory contaminants.
Evaluation of Potential Public Health Hazards. PAHs and metals were detected in the surface soil outside of Andrews AFB, within the flightline pattern. However, the concentrations detected were too low to be of health concern when assuming lifetime residential exposure; therefore, no apparent public health hazard exists from exposure to soils in the flightline. Please refer to Appendix B for further details concerning how ATSDR estimated exposure doses and determined health effects. The area where the samples were taken is cropland, therefore, it is possible that crops grown in this soil could uptake the chemicals. Strawberries from this field were sampled at the same time as the soil. An evaluation of exposures from eating the strawberries is discussed in the following Surface Water and Sediment discussion under the "Exposure of recreational users to contamination in Piscataway Creek" section.
- Pathway: Surface Water and Sediment
Have the surface waters and sediments been contaminated to levels that might be harmful to recreational users?
On-Site Surface Water and Sediment
- Children who play in the unnamed tributary to Paynes Branch are not being exposed to harmful levels of contamination.
- Children who may access Cabin Branch and play in the water and sediments are not being exposed to harmful levels of contamination.
- Recreational users of the Base Lake are not being exposed to harmful levels of contamination.
Off-Site Surface Water and Sediment
- People recreating in the many parks along Piscataway Creek are not being exposed to harmful levels of contamination.
- People who use Henson Creek for recreational purposes are not being exposed to harmful levels of contamination.
- People who recreate along the banks of Charles Branch are not being exposed to harmful levels of contamination.
This section discusses the hydrology, surface water and sediment use, and expected exposures to recreational users of both on-site and off-site surface water bodies that receive potential contamination from Andrews AFB.
Andrews AFB sits atop a north-south drainage divide, in the vicinity of the runways, that separates the Potomac River Basin to the west and the Patuxent River Basin to the east. Surface water drains on the west side of the base into the Potomac River via Henson Creek, Meetinghouse Branch, Paynes Branch, and Piscataway Creek. Surface water on the east side of the base drains into the Patuxent River via Cabin Branch and Charles Branch (Dames & Moore 1992; Tetra Tech 1996). Piscataway Creek originates in the southeast corner of Andrews AFB and receives drainage from nearly 1,500 acres of the base. The Base Lake is the largest open water body on base and is supplied with water from a 780-feet deep water supply well located adjacent to it. Four smaller ponds also exist on base--two south of the Base Lake and two in a residential area in the northern section of the base (Andrews AFB 1996).
Surface Water and Sediment Use
Both the Potomac and Patuxent River Basins are designated Class 1 waters by the State of Maryland. These waters can be used for recreation, fishing, and the propagation of aquatic life and wildlife (Tetra Tech 1996). In addition to recreation, Piscataway Creek was used to irrigate a berry farm that was located east-southeast of Andrews AFB prior to 1995. Fishing and non-motorized boating are permitted in the Base Lake.
On-site surface water and sediment
Three on-site surface water bodies are discussed in this section: the unnamed tributary to Paynes Branch, Cabin Branch, and the Base Lake. The unnamed tributary to Paynes Branch is a small stream that runs through two residential areas. Tributaries to Cabin Branch (Cabin Creek North and Cabin Creek South) are located in the northeast corner of Andrews AFB near family housing units. Even though Andrews AFB has not designated these areas as recreational, it is possible that older children could occasionally play in these creeks. The Base Lake is a designated recreational area.
Potential exposure of recreational users to contamination in the unnamed tributary to Paynes Branch
Nature and Extent of Contamination.The unnamed tributary to Paynes Branch (sometimes also referred to as Chips's Creek) originates from three storm drains that are located west of the Family Housing Units at 2132 Richmond Drive and south of San Antonio Boulevard (EA Engineering 1993). The creek runs through undeveloped grass and wooded lots and eventually through additional Family Housing Units. The creek is easily accessible to children who live in the nearby Family Housing Units. In 1992, surface water and sediment from the unnamed tributary to Paynes Branch were analyzed for VOCs, SVOCs, and TPH. One SVOC and TPH were detected in the surface water. Nineteen SVOCs and TPH were detected in the sediment (Table 6) [EA Engineering 1993].
Evaluation of Potential Public Health Hazards. After calculating conservative recreational exposure doses for chemicals detected in the surface water and sediment in the unnamed tributary to Paynes Branch (please refer to Appendix B for further details), ATSDR determined that none of the contaminants were detected at levels of health concern. Therefore, no apparent public health apparent hazard exists for children who play in the unnamed tributary to Paynes Branch.
Potential exposure of recreational users to contamination in Cabin Branch
Nature and Extent of Contamination. Cabin Branch begins in the northeast portion of Andrews AFB as Cabin Creek North and Cabin Creek South. The two branches surround family housing units to the north and south, respectively. Cabin Branch receives surface water runoff from three IRP sites (SS-12, ST-14, and a portion of ST-19). In addition, groundwater from ST-14 is seeping into Cabin Creek South, which begins just north of Fetchet Avenue. The creek can be accessed by older children who live in the nearby Family Housing Units. In 2000, surface water, sediment, and seep samples from Cabin Branch were analyzed for VOCs, SVOCs, metals, and inorganics. Four VOCs, one SVOC, and 19 metals were detected in the surface water. Seven VOCS, 12 SVOCs, and 20 metals were detected in the sediment. Twelve VOCs, one SVOC, and 19 metals were detected in the seep (Table 7) [IT Corporation 2000b].
Evaluation of Potential Public Health Hazards. ATSDR calculated conservative recreational exposure doses for chemicals detected in the surface water, sediment, and seep in Cabin Branch and determined that none of the contaminants were detected at levels of health concern. Therefore, no apparent public health hazard exists for children who may play in Cabin Branch. Please refer to Appendix B for further details concerning how ATSDR estimated exposure doses and determined health effects.
Potential exposure of recreational users to contamination in the Base Lake
Nature and Extent of Contamination.The 14-acre Base Lake was created in the early 1960s by filling a gravel pit with water from an artesian well. The Base Lake is shallow, mostly under 6 feet deep (EA Engineering 1995b). Area fishermen have been known to bring fish caught elsewhere to the lake. The lake is not currently stocked by Andrews AFB; however, there are discussions about stocking the lake in the future to promote recreational fishing.There are also some discussion about future development of the Base Lake area for additional recreational activities.
The lake may be impacted by surface runoff or shallow groundwater from LF-06 and LF-07. Both landfills were created by filling in the same gravel pit, creating a potential for landfill leachate to impact the Base Lake directly and/or the well that feeds the lake. In 1993, two samples each of surface water, sediment, and fish were analyzed for VOCs, SVOCs, pesticides, PCBs, and metals. The fish samples were comprised of composites of two different species of fish--three channel catfish and nine chain pickerel. Catfish is a type of fish that is typically eaten, however, pickerel is not. Pickerel is more commonly fished for sport rather than food. Two SVOCs and six metals were detected in at least one of the surface water samples. One VOC, 2 SVOCs, and 11 metals were detected in at least one of the sediment samples. One VOC, four SVOCs, two pesticides, two PCBs, and eight metals were detected in fish samples (Table 8) [Andrews AFB 1993].
Evaluation of Potential Public Health Hazards. Recreational exposure doses were calculated for the chemicals detected in the Base Lake. Please refer to Appendix B for further details concerning how ATSDR estimated exposure doses and determined health effects. All concentrations in the surface water, sediment, and fish samples were at levels too low to result in adverse health effects and pose no apparent public health hazard to the recreational users.
Off-site surface water and sediment
Piscataway Creek, Henson Creek, and Charles Branch receive surface water runoff from IRP sites at Andrews AFB. The majority of these creeks are located off base and travel for several miles before discharging into the Potomac and Patuxent Rivers. Area residents may have contact with the surface water and sediment in these creeks where the creeks run near their homes. Also, visitors to several local parks located along the creeks may use them for recreational purposes.
Potential exposure of recreational users to contamination in Piscataway Creek
Nature and Extent of Contamination. Piscataway Creek exits Andrews AFB on the east-southeast border and flows south and southwest for about 13 miles before it reaches the Potomac River. Sections of the Piscataway Creek Stream Valley Park exist at several locations along the creek. In addition, the U.S. Naval Communications Detachment, Boys Village of Maryland, and Louise F. Cosca Regional Park are located adjacent to it.
In the past, water from Piscataway Creek was used to irrigate and freeze protect a pick-your-own berry farm adjacent to Andrews AFB's east-southeast border. In spring 1992, irrigation water that was sprayed on strawberries was suspected of containing an aqueous film forming foam. Andrews AFB collected and analyzed strawberries and raspberries in the spring of 1992 (Andrews AFB 1993). During this investigation, two pesticides and three metals were detected in one or more samples (Table 9). In 1993, two strawberries were analyzed for contamination. One was picked in the field, the other was dipped in the creek at a place where irrigation water was withdrawn. Four SVOCs and six metals were detected in at least one of the samples (Table 9). In 1995, Andrews AFB bought the property to increase the flightline safety buffer or "crash zone" around the base.
Piscataway Creek receives potentially contaminated surface water runoff and shallow groundwater discharge from several IRP sites that are located at its headwaters (FT-03, FT-04, LF-05, LF-06, LF-07 and AOC-27). In 1993, 13 surface water, 17 sediment, and seven composite fish samples from Piscataway Creek were collected and analyzed for VOCs, SVOCs, pesticides, PCBs, PAHs, inorganics, and metals (Andrews AFB 1993). Two SVOCs and 10 metals were detected in the surface water. Two VOCs, nine SVOCs, 15 PAHs, and 15 metals were detected in sediment samples. Three VOCs, 12 SVOCs, four pesticides, two PCBs, and 12 metals were detected in fish samples (Table 9). In 1994, surface water and sediment samples were collected and analyzed for VOCs, SVOCs, pesticides, PCBs, metals, and inorganics. Surface water was collected during a dry event and after a storm event. A total of two VOCs, three SVOCs, two pesticides, and 21 metals were detected between both sampling periods. Four VOCS, 18 SVOCs, one pesticide, and 20 metals were detected in the sediment (Table 9) [EA Engineering 1995a].
Evaluation of Potential Public Health Hazards. Recreational exposure doses were calculated for the chemicals detected in Piscataway Creek. The exposure evaluation indicates that incidental exposure to the low levels of contaminants in the surface water and sediment in Piscataway Creek is not expected to cause adverse health effects to recreational users. ATSDR calculated exposure doses based on recreational fishing, assuming that people ate fish from the creek up to seven times per month. Based on this exposure scenario, the fish are safe to eat. ATSDR concludes that no apparent public health hazard exists for recreational users of Piscataway Creek. Please refer to Appendix B for further details concerning how ATSDR estimated exposure doses and determined health effects. Exposure doses were also calculated for people who may have eaten strawberries that were irrigated with water from Piscataway Creek. None of the detected chemicals were at levels of health concern. Based on the limited sampling, no apparent past public health hazard existed for people who ate strawberries from the berry farm.
PGCHD has indicated that there are people in the county known to subsist on fish (i.e., people who rely on fishing for a principle food source). People consuming fish from Piscataway Creek at this level (e.g., eating 17 fish meals a month) may be exposed to harmful levels of contaminants. However, the upper reaches of Piscataway Creek (where the sampling occurred) is not a particularly productive fishing location (Andrews AFB 1993). People are known to subsist on fish about 13 miles downstream where Piscataway Creek enters the Potomac River. The current sampling is not adequate enough to make a determination whether sources of contamination from Andrews AFB might effect fish caught 13 miles downstream. In addition, each fish sample is a composite of three to five fish of the same genus or species. Analyses based on this type of sampling may not accurately represent the portions of the fish that are commonly eaten and may actually result in overinflated exposures being calculated. As stated above, eating moderate amounts of fish is not expected to present a public health problem.
The data for Piscataway Creek was collected prior to the construction of the golf course. Creating a golf course on top of a former landfill increases the amount of water that is applied onto the landfill (e.g., from watering the golf course) and creates a potential for increased groundwater leaching and/or surface water runoff into Piscataway Creek. However, groundwater modeling, completed before construction began, estimated that the concentration of chemicals that would reach Piscataway Creek would be less than it was prior to the construction of the golf course because the increased irrigation would dilute the leachate (EA Engineering 1995b). In addition, Andrews AFB has implemented best management practices to limit the amounts of water and pesticides used on the golf course. Sediment and erosion control mechanisms (e.g., grass swales and berms) were also applied to minimize the impacts to nearby surface waters (EA Engineering 1995b).
Potential exposure of recreational users to contamination in Henson Creek
Nature and Extent of Contamination. Henson Creek exits Andrews AFB on the northwest corner and travels about 7 miles before joining Broad Creek and entering the Potomac River. It flows through the Morningside Community, Rosecroft Raceway, and Henson Creek Golf Course. In addition, Henson Creek Stream Valley Park is located along a majority of the creek. Henson Creek potentially receives contaminated sediment from a drainage ditch located just north of SS-21, the Engine Test Cell. Surface water and sediment from the drainage ditch was sampled for petroleum related compounds in 1994, and sediment was sampled again in 1996. Some petroleum contamination has been detected in the sediment of Henson Creek, however, no harmful components of fuels, such as BTEX (benzene, toluene, ethyl benzene, and xylenes) and naphthalene, were found above detection limits in either media (IT Corporation 1996b).
Evaluation of Potential Public Health Hazards. Even though there is evidence of petroleum release to Henson Creek, no hazardous components of fuels were found above detection limits. Therefore, no apparent public health hazard exists for people using Henson Creek for recreational purposes.
Exposure of recreational users to contamination in Charles Branch
Nature and Extent of Contamination. Charles Branch exits Andrews AFB on the eastern border and travels southeast and east for about 7 miles before joining Western Branch about a third of a mile before it enters the Patuxent River. Charles Branch flows past the Melwood Community, Rosaryville State Park, Marlton Community Park, Charles Branch Stream Valley Park, and a portion of the Patuxent River Park. Charles Branch receives surface runoff from three IRP sites (ST-08, SS-22, and AOC-25). Surface water and sediment were sampled in 1992 for VOCs, SVOCs, metals, and TPH and the again in 1996 for petroleum related compounds. Two VOCs and 13 metals were detected in the surface water and three VOCS, 17 SVOCs, 19 metals, and TPH were detected in the sediment (Table 10) [Dames & Moore 1994a; IT Corporation 1997].
Evaluation of Potential Public Health Hazards.Exposure to contaminants in Charles Branch could occur incidentally when nearby residents or visitors use the water for recreational activities. ATSDR calculated conservative recreational exposure doses for the chemicals detected in the surface water and sediment of Charles Branch. Please refer to Appendix B for further details concerning how ATSDR estimated exposure doses and determined health effects. None of the chemicals were detected at levels of health concern, therefore, no apparent public health hazard exists for people using Charles Branch for recreation.
- Pathway: Groundwater
Has contaminated groundwater migrated to nearby drinking water wells? If so, has that contamination resulted in adverse human health effects?
- Contaminated groundwater is present on base at LF-05 at levels of health concern. At this time it does not appear that the contamination is reaching any drinking water wells. However, ATSDR is concerned that additional unidentified wells may exist in the area downgradient of LF-05 and recommends that PGCHD perform an off-base shallow groundwater well survey. If additional off-base drinking water wells are identified, ATSDR further recommends that the Air Force test the well(s) to determine whether any harmful exposures are occurring.
- In 1984, heating oil was released into the environment from a leaking UST at Davidsonville Transmitter Station. Residents and employees of Davidsonville Transmitter Station rely on groundwater wells as their drinking water source. Site investigation information is limited; therefore, not enough information exists to rule out the potential for groundwater contamination at SS-11. ATSDR recommends that Andrews AFB sample and analyze water from the existing monitoring wells at Davidsonville Transmitter Station to confirm whether groundwater contamination is located at the site.
Groundwater at Andrews AFB is first encountered at 50 feet or less below ground surface in the Upland and Terrace deposits. Together these deposits form the shallow groundwater aquifer. The principal source of recharge (i.e., water supply) is through precipitation penetrating the ground to fill the voids that exist between soil particles in the deposits. The movement of the shallow groundwater is unconfined and specific for each water-bearing unit--the flow tends to be towards local surface waters. Below this water table aquifer are the Calvert, Nanjemoy, and Marlboro formations, which separate the shallow groundwater aquifer from the deeper regional aquifers that also exist under Andrews AFB. The first aquifer under this clay layer is in the Aquia formation. Below the Aquia formation is an alternating sequence of aquifers (Cretaceous aquifers) and confining layers. Groundwater has a tendency to move from areas of high water levels to areas of low water levels. Andrews AFB and the remote facilities are located in areas of high water levels and, therefore, tend to recharge other hydraulically joining aquifers in neighboring counties (Dames & Moore 1992; Engineering-Science 1985, U.S. Department of the Interior 1989).
Andrews AFB and most homes and businesses in the area receive their drinking water from WSSC, a local municipal distribution system (Dames & Moore 1992). WSSC's source of water is surface water from the Potomac and Patuxent Rivers, as opposed to groundwater under the base. Prior to the 1940s, it was common to obtain water from shallow wells (0 to 50 feet deep) that supplied low yields (2 to 5 gallons per minute). It is uncertain at this time how many residents in the vicinity of Andrews AFB are using shallow groundwater wells. It is illegal to install shallow wells in Prince George's County because of the potential for the shallow unconsolidated aquifer to be contaminated. However, some historic wells were in place before the permitting system was established. According to MDE's groundwater well database, which may not include wells predating the mid-1970s or wells that were hand-dug into the early 1980s, 16 domestic wells exist within a half mile radius of Andrews AFB. Eleven of the wells draw water from the deep aquifers and one from the Upland Deposits. The depths of four wells were not determined. Several of the deep aquifers (e.g., the Aquia formation) that underlie Andrews AFB supply water to southern Prince George's, Ann Arundel, Charles, and St. Mary's Counties. The Base Lake also receives its water supply from a well that withdraws from one of the deep aquifers (Andrews AFB 1996; EA Engineering 1995a).
Several contaminated groundwater plumes exist at Andrews AFB. Plumes of benzene and carbon tetrachloride are located near a former fire training area (FT-04); the groundwater flow is towards the northwest (i.e., towards the flightline) where no drinking water wells are located. Groundwater contaminated with VOCs has migrated 350 to 500 feet off base from a former landfill, LF-05. A BTEX plume originating from a former military gas station (ST-08) exists entirely on base, in the eastern part of Andrews AFB near Pennsylvania Avenue. The POL Storage Yard (SS-13), located along the eastern border, has free product in the groundwater and a plume with benzene as the primary contaminant of concern. The former East Side Service Station (ST-14), located in the northeast, has three co-mingled plumes of trichloroethylene (TCE)/cis-dichloroethylene (DCE), carbon tetrachloride, and BTEX that exist entirely on base. Plumes of BTEX; methyl, tert-butyl ether; and TPH exist on base at the Army/Air Force Exchange Station (ST-17) on the west side of Andrews AFB. Free-phase and dissolved-phase hydrocarbon plumes exist at ST-18, the Family Housing Units at 2132 Richmond Drive. A BTEX plume originates from the Engine Test Cell (SS-21), located in the northwest corner of the base. Free product, BTEX, and three chlorinated solvent plumes (two 1-chlorohexane plumes and one TCE/DCE plume) originating from Hangar 13 (SS-22) have been identified to exist entirely on the eastern section of the base.
LF-05 (Leroy's Lane Landfill) and SS-11 (Davidsonville Fuel Oil Spill) are the only two source areas evaluated in this public health assessment because they are the only two with the potential for exposure to occur. LF-05 is the only IRP site at Andrews AFB that is known to have contaminated groundwater migrating off site. Very little information is known about the groundwater at SS-11, therefore, the potential for off-site contamination exists.
Exposure of off-base residents and businesses to contaminated groundwater from LF-05
Nature and Extent of Contamination. LF-05 is a former landfill that was used from the 1960s to the 1980s to dispose of a variety of wastes generated at Andrews AFB. General refuse, construction rubble, and fly ash was disposed of in trenches. Prior to the mid-1970s, waste solvents, dilute process wastes, and waste oils from shop operations were disposed of in a southern pit. In the mid-1970s, two 25,000 gallon USTs were installed to hold the liquid waste until it could be removed by an off-site contractor. Currently, several feet of soil cover the site.
The groundwater at LF-05 is shallow, about 16 to 20 feet below ground surface. The groundwater flow is to the east-southeast. The average groundwater flow is 3 to 4 feet a year (Dames & Moore 1992). Aggregate Industries owns the property to the south of LF-05 and Hexagon Developers owns the property east and southeast (PGCHD 1997).
In 1989, nine monitoring wells were installed at LF-05. Groundwater samples were collected from these wells and analyzed for VOCs, SVOCs, pesticides, PCBs, and metals. In 1995, 30 direct-push groundwater samples were taken to attempt to characterize the plume boundaries. Based on these data, five new monitoring wells were installed in 1995 and 1996, three of which were located off base. Groundwater was sampled for VOCs, SVOCs, pesticides, PCBs, and metals from these wells in 1996. In 1998, quarterly groundwater monitoring was initiated at LF-05. The monitoring wells were tested for a target list of VOCs, SVOCs, pesticides, PCBs, and metals. Between these sampling events 15 VOCs, 12 SVOCs, and 22 metals were detected in the groundwater (Table 11) [Dames & Moore 1992; EA Engineering 1996; EA Engineering 1999].
PGCHD recently identified and sampled (on August 8, 2000, August 30, 2000, and October 10, 2000) a groundwater seep outside of LF-05 on Foxley Road. The concentration of chlorobenzene (332.2 ppb) was much higher than the levels reported by Andrews AFB in their off-site monitoring wells (PGCHD 2000).
Evaluation of Potential Public Health Hazards. Of the chemicals detected in the groundwater at LF-05, only four VOCs (1,2-dichloroethane, benzene, chlorobenzene, and methylene chloride), two SVOCs [2,4-dimethylphenol and bis(2-ethylhexyl)phthalate], and seven metals (arsenic, barium, cadmium, iron, lead, manganese, and thallium) were detected at slightly elevated levels. Of these, only manganese was detected at levels of potential health concern in off-site monitoring wells. The remaining contaminants were either not detected off site or were at levels too low to be of health concern. Please refer to Appendix B for further details concerning how ATSDR estimated exposure doses and determined health effects. It should be noted that manganese was detected at a level of health concern in a monitoring well and not in a drinking water well. Unless people are drinking the contaminated groundwater, no exposures exist.
Public water is supplied to the residential areas outside of LF-05, but reportedly, there are at least three off-site, private groundwater wells around LF-05 (MITRE, 1993). PGCHD has tried to locate these three wells; however, they and Andrews AFB are aware of only two wells in the area. Both are deep wells and have not been reported as being used to supply drinking water. The groundwater contamination is located in the shallow aquifer. Deep wells, if properly built and maintained, would not normally be impacted by shallow groundwater contamination, because their water supply is from a deeper aquifer that is not contaminated. However, if there is a fault in the casing, the contaminated groundwater could drain down the outside of the well and into the deeper aquifer.
One of the known wells is located on property owned by Hexagon Developers. It is not registered with PGCHD, so no official information is available for this well. But according to PGCHD, it appears to be a deep well (i.e., estimated to be 250 feet below ground surface). It was being used by Gradall Specialists, Inc. in 1992, to provide water for bathroom and kitchen use. Employees at Gradall Specialists, Inc. were reportedly using bottled water as their drinking water supply. However, the faucets are not labeled as non-potable water. The well on Hexagon Developers property was sampled by PGCHD in 1992 and 2000, and was reported to show "no signs of contamination" (PGCHD 1992a, State of Maryland 2000). This well was also sampled by Andrews AFB in 1997. At that time, several metals and one VOC were detected in the well (IT Corporation 1998), however, the concentrations were too low to be of health concern if people were to be drinking water from this well on a daily basis (Table 12). Please refer to Appendix B for further details concerning how ATSDR estimated exposure doses and determined health effects.
The other well is located on Aggregate Industries property. The well is located in a deep aquifer (over 400 feed below ground surface) and was abandoned in 1998. It was used for washing sand and gravel and was possibly used to supply water to a bathroom. ATSDR is not aware of any sampling at this well.
As discussed in the paragraphs above, contaminants were detected at levels of health concern in on-site and off-site monitoring wells (Table 11 and Table 13). To this time, no contamination of health concern has been detected in drinking water wells. However, since the potential exists for contamination to migrate off site with time, it is important for Andrews AFB to accurately define and monitor the groundwater contamination at LF-05 and in surrounding areas. In addition, if access is granted, state and county regulators should confirm that no shallow groundwater wells are being used in the area and that the known wells are properly maintained. Although, it does not appear that the contamination is reaching any private wells used for drinking, there is a concern that all wells in the area have not yet been identified by Andrews AFB or PGCHD (MITRE 1993). For this reason, ATSDR concludes that an indeterminate public health hazard exists for people who may be using shallow groundwater wells in the vicinity of LF-05. If it can be confirmed that no shallow groundwater wells are being used to supply drinking water in the area downgradient from LF-05, then it would not be expected that groundwater contaminants from LF-05 would present a public health hazard.
Potential exposure of off-base residents and on-site employees to contaminated groundwater from SS-11
Nature and Extent of Contamination. In May 1984, a 2,000-gallon UST at the Davidsonville Transmitter Station (SS-11) was found to be leaking when fuel consumption increased and petroleum was detected in two utility vaults beneath the Transmitter Building (Gannett Fleming 1997). The 2,000-gallon UST was connected to four 20,000-gallon ASTs. This system supplied the station's boilers with No. 2 heating oil using a pressure-gravity feed. In June 1984, four monitoring wells were installed and 1/100 of an inch of free product was detected in one of the groundwater monitoring wells (USAF 1984). Based on these findings, the tank was excavated and all visibly contaminated soil was removed in June 1984. Maryland Department of the Environment closed their case with the site in December 1985.
Groundwater at the Davidsonville Transmitter Station is reported to be five to eight feet below ground surface in the Terrace Deposits. Below the Terrace Deposits is a clay layer that separates the shallow groundwater from the deeper aquifer, the Aquia Formation. The Aquia Formation is the principal source of water for Anne Arundel County--where the Davidsonville Transmitter Station is located (Engineering-Science 1985).
Evaluation of Potential Public Health Hazards. Other than the report that free product was detected in a monitoring well (Gannet Fleming 1997; Engineering-Science 1985; USAF 1984), no other data exist to evaluate SS-11. Because USTs are not typically buried deep, ATSDR assumed that the contamination was detected in the shallow groundwater. The potential existed for a large amount of free product to have leaked--it was reported that 2,000 more gallons of heating oil were used in the months of February, March, and April 1984 than the previous year (MDE 1984). On the other hand, the contractor hired to drill and sample the monitoring wells reported that "there did not appear to be an extensive occurrence of fuel oil contamination in the subsurface" (Engineering-Science 1985, p. 4-34).Another contractor concluded that "Because of the extensive cleanup associated with this spill, no significant potential for contamination exists and no follow on investigation is warranted." (Engineering-Science 1985, p. 5-8).
Residences located in the immediate vicinity of Davidsonville Transmitter Station receive their household water from private groundwater wells. The closest border is about 3/8-mile northwest from the leak. Even though ATSDR does not have information about the depths of the private residential wells, they are probably deep, and draw water from the Aquia Formation. The station also receives its water from a deep groundwater well (about 125 feet below ground surface) that is located north of the leaking UST. The station's supply well has been sampled on a regular basis and it is assumed that private wells were also. Moreover, deep wells would not typically be impacted by shallow groundwater contamination as long as the wells are in good repair and the casing is sealed.
Even though it was reported that underground contamination was minimal, ATSDR cannot provide a specific conclusion without the supporting data. Although there is no indication that private wells have been impacted, there is a possibility that if contamination existed, heating oil that leaked from the UST could have migrated into an area where groundwater wells were used. Contamination of deeper wells might be possible if these wells are not in good repair. Therefore, unless information (past or current) can be provided to support the statement that no extensive contamination existed or exists in the groundwater, ATSDR concludes that an indeterminate public health hazard exists for people and employees obtaining their drinking water from groundwater wells in the vicinity of Davidsonville Transmitter Station. If past supporting information cannot be located, ATSDR recommends that Andrews AFB sample the remaining monitoring wells at Davidsonville Transmitter Station to ensure that extensive contamination does not exist.
- Pathway: Soil Gas
Are people who occupy buildings above groundwater plumes being exposed to harmful levels of contaminants through soil gas migration?
- The levels of VOCs detected under occupied buildings are not at levels of health concern. However, the accumulation of combustible gases in enclosed spaces creates the potential for explosion and fire to result if appropriate precautions are not taken.
VOCs can volatilize from groundwater resulting in an accumulation of soil gas in the small spaces between soil particles. ATSDR recognizes that exposure to soil gas becomes a concern when high concentrations of VOCs migrate via soil gas into basements through cracks in the foundation walls of buildings. VOCs may become concentrated in enclosed spaces, creating a potential for human exposure through inhalation and skin contact. The degradation products of TCE (e.g., vinyl chlorides) are particularly harmful if a person is exposed to high concentrations. Gaseous petroleum hydrocarbons or methane accumulating in enclosed spaces is a physical safety concern because explosions and fires can occur.
Nature and Extent of Contamination. Nine IRP sites at Andrews AFB have petroleum contamination plumes: FT-04 (former fire training area), LF-05 (former landfill), ST-08 (UST leak), SS-13 (POL Yard), ST-14 (service station), ST-17 (gas station), ST-18 (UST leak), SS-21 (engine test cell), and SS-22 (Hangar 13). The groundwater contamination has been characterized at each site. Free product is present in the groundwater at SS-13, ST-18, and SS-22 and four of these sites (FT-04, LF-05, ST-14, and SS-22) also have chlorinated solvent plumes. A soil gas survey was completed for ST-08 and LF-05 and an indoor air survey was performed in residential housing units at ST-18. At some sites, buildings are located above the groundwater contamination, creating the potential for groundwater contaminants to volatilize, enter the buildings, and accumulate in enclosed spaces.
Evaluation of Potential Public Health Hazards. ATSDR evaluated the level of groundwater contamination at each of the nine IRP sites with plumes. None of the concentrations that were detected in the groundwater or soil gas underneath the buildings were at levels of health concern. The air sampling at the residential housing units were also at levels considered to be safe. Therefore, no apparent public health hazard exists for occupants of buildings above contaminated groundwater plumes.