PUBLIC HEALTH ASSESSMENT
DOVER AIR FORCE BASE
DOVER, KENT COUNTY, DELAWARE
|Pathway||Elements of an Exposure Pathway||Comment|
|Source||Media||Point of Exposure||Route of Exposure||Time Frame||Exposed Population|
|Completed Exposure Pathways|
|Off-Base Groundwater |
Exposure to VOCs in off-site drinking water wells
|Former DAFB activities that resulted in the Area 5 plume||Groundwater||Gooch Trailer Park welland other off-site wells||Ingestion, dermal contact, and Inhalation||Past (pre-1984)||Gooch Trailer Park residents, users of other affected nearby water supply wells|| |
Past: Several water supply wells southwest of DAFB contained VOCs above ATSDR's CV and EPA's MCL when they were first sampled in 1984. The well at the Gooch Trailer Park contained benzene. Exposure occurred, but not likely at levels of health concern.
Current and Future: The USAF provides residents of the trailer park (and other properties) with DAFB drinking water. Construction to connect Gooch Trailer Park, the P&F motorcycle business, and a residence to Tidewater Municipal Water Service began in September 2003.
|On-Base Groundwater |
Exposure to arsenic in DAFB drinking water wells
|Unknown, likely natural sources||Groundwater||DAFB Drinking water taps||Ingestion||Past |
|DAFB residents and workers|| |
Past and Current: EPA has recently lowered the safe drinking water standard for arsenic from 50 parts per billion (ppb) to 10 ppb. Although arsenic concentrations in the drinking supply wells that draw water from the deep Piney Point Aquifer have been below the old standard over the past 20 years, the levels in some of the wells exceed the new standard. The arsenic is believed to be from natural deposits in the ground. These levels are not expected to pose harm to individuals who rely on the base water supply.
Future: DAFB plans to close the affected wells in late 2003.
|Potential Exposure Pathways|
|Indoor Air |
Exposure to vapors in homes of the Eagle Heights Housing Area situated above the Area 6 plume
|Organic compounds in groundwater Area 6 plume from DAFB may have volatilized and seeped into basements of homes in the base Eagle Heights Housing Area.||Indoor air||Eagle Heights homes||Inhalation||Past |
|Certain residents of the Eagle Heights Housing Area||Past, Current, Future: People who live in homes above the groundwater plume in the Eagle Heights Housing Area may have been exposed to low levels of contaminants that have volatilized from the plume. Modeling predicts that the contaminants exist in homes above the plume, but at levels lower than those associated with adverse health effects. This modeling is very health protective because it uses the highest levels of VOCs found in the water and assumes that all of the VOCs volatilized into the air and that no dissipation occurred.|
|Lead Hazards |
Exposure of children to lead-based paint in base housing
|Lead-based paint in DAFB base housing built before 1978||Lead-based paint||Certain DAFB housing built before 1978 with chipped and peeling painted surfaces||Incidental ingestion||Past |
|Children who live in base housing built before 1978 with signs of chipped or peeling painted surfaces|| |
Past: Certain homes at DAFB contain lead-based paint. Children living at DAFB are screened for lead poisoning at their 12-month well baby visits. Children under 7 who are at risk of lead exposure, who have not previously been tested, or with elevated blood lead levels require additional care. No cases of lead poisoning have been confirmed at DAFB.
Current and Future: DAFB is demolishing housing possibly maintained with lead-based paint. Residents are advised of temporary measures to reduce lead hazards in their homes. Lead exposure is assessed and blood lead levels screened at a child's 12-month well baby visit, and as needed until the child reaches the age of 7. These actions would be expected to result in a reduced potential for exposure to lead in the home and risk of lead poisoning.
|Current Land Use |
Exposure to landfill material or gases at ball fields and an adjacent school
|Former landfill D-11 (LF26) used for the disposal of construction rubble and general refuse in the 1950s and 1960s||Landfill material and landfill gases||The ball field and school||Dermal contact; possible inhalation and explosion hazards from gases||Past |
|Children and other visitors to the field and school||Past, Current, and Future: Only low levels of contaminants have been detected in the soil and groundwater at/near the landfill. DAFB covered the landfill with a layer of soil and grass that limit direct contact with the landfill material. Due to the age and the contents of the former landfill, limited amounts of landfill gases, if any at all, are emitted at this time.|
|Location||Contamination (ppb)||Date Sampled||Comment||Action/Status|
|Gooch Trailer Park||TCE 7.2 ppb |
PCE 231 ppb
Benzene 175 ppb
Toluene 5.9 ppb
|June 1984||TCE, PCE, and benzene exceed their MCL and ATSDR CV.||The water supply well has not been used since 1984, when DAFB connected the Gooch Trailer Park to the DAFB water supply.|
|Private Residence and P&F Motorcycle Business||TCE 4.2 ppb |
PCE 813 ppb
|June 1984||PCE exceeds its MCL and ATSDR CV of 5 ppb.||DAFB voluntarily connected the property to the base water supply in 1984. The property has received water from the base since 1984.|
|Paradee Gulf Station||TCE 20 ppb |
PCE 3.6 ppb
|June 1984||TCE exceeds its MCL and ATSDR CV of 5 ppb.||DAFB voluntarily connected the property to the base water supply in 1984. A 1989-1990 DelDOT investigation suggests that some of the off-site drinking water well contamination may have originated from the Paradee property. DelDOT acquired and demolished the property in the early 1990s. The SR-1 construction was completed in the late 1990s.|
|Eddie's Sweet-N-Eats||Not available||1984||NA||Eddie's Sweet-N-Eats went out of business in 1984, before DAFB provided water hook up to other neighboring properties.|
|Giacomos Pizza||TCE 350 ppb||1984||TCE exceeds its MCL and ATSDR CV of 5 ppb.||The property was acquired by DelDOT for the SR-1 highway construction and subsequently demolished in the early 1990s.|
|Texlers Exxon||TCE 80 ppb||NA||TCE exceeds its MCL and ATSDR CV of 5 ppb.||The property was acquired by DelDOT for the SR-1 highway construction and subsequently demolished in the early 1990s. It is not known if this property received an alternative water supply before it was demolished.|
|Hastings Laundry||TCE 13.5 ppb||NA||TCE exceeds its MCL and ATSDR CV of 5 ppb.||The property was acquired by DelDOT in late 1980s for the SR-1 highway construction property and subsequently demolished. The Hastings site was subsequently listed as a Superfund site as a result of chlorinated solvent releases. It is currently undergoing a cleanup remedy under DNREC authority.|
CV=ATSDR's comparison value; DelDOT=Delaware Department of Transportation; MCL=EPA's maximum contaminant level; NA=Information was not available; ppb =parts per billion, TCE=trichloroethylene.
Source: DNREC 1984a; DAFB 2003.
|December 1983||As part of RCRA sampling, DAFB detects high levels of industrial solvents in groundwater near on-base waste lagoons.|
|June 1984||The Division of Public Health samples off-base water supply wells located in the direction of groundwater flow from the lagoons. High levels of VOCs and fuel-related compounds are found in the water supply wells. Suspected on-base sources are identified. The Division of Public Health issues a notice to residents of the trailer park to refrain from drinking the water.|
|July 1984||DAFB supplies the residents of the trailer park with an emergency water tank supply.|
|October 5, 1984||DNREC requests that the DAFB provide bottled water to residents of the trailer park, as well as to the Gulf station, Eddie's Sweets-N-Eats, and another private residence.|
|November 1984||DAFB issues a memorandum stating the base's intent to connect Gooch's Trailer Park and P&F Motorcycle Facilities to the DAFB water supply.|
|November 28, 1984||DAFB sends a letter to inform DNREC, Division of Environmental Control, of the base's intent to close and eliminate the industrial waste lagoon and accelerate the Phase II IRP investigation. This memorandum also states the base's intent to temporarily connect the "three" affected water supply wells west of DAFB to the DAFB water supply.|
|January 14, 1985||DAFB receives approval from the Division of Public Health to extend the existing water line at DAFB to serve Gooch's Trailer Park.|
|July 12, 1985||CDC memorandum indicates that TCE levels detected in wells at Giacomos Pizza (350 ppb), Texlers Exxon (80 ppb), and Hastings Laundry (13.5 ppb) render the well water unfit for human consumption.|
|July 1985||Memorandum from DAFB commander states the base's intent to connect the Gooch Trailer Park, P&F Motorcycles, and Paradee Gulf Gas Station to the DAFB water supply and furnish water until a suitable private water source is identified.|
Source: DNREC 1984a, 1984b, 1984c; DAFB 2003; USAF 1984.
|OT51||Former maintenance hangars Bldgs. 794, 789, 790, and 791||1,2-DCE |
|SS20||Near Bldg. 639||PCE|
|OT41||IWCD, near the motor pool||TCE |
|OT43||Minor source. Oil/water separator recommended for NFA.||BTEX|
|OT44||An oil/water separator||TCE |
|Paradee Gulf Station||BTEX|
|P&F Motorcycle Shop||PCE and TCE|
Source: Dames & Moore 2001.
|A||Cheswold||Replaced in 1993 due to "pulling sand"|
|C||Cheswold||Replaced in 1993 due to "pulling sand"|
|D||1963||Piney Point||To be used for fire suppression. DAFB will drill a replacement well in the Cheswold Aquifer in 2003.|
|E||1983||Piney Point||To be abandoned in 2003.|
Source: DAFB undated, DAFB 2003.
|Year||Maximum Arsenic Concentration (ppb)|
|Main Base and Eagle Heights Wells |
|Eagle Meadow Wells |
|1980-2001 (Well D only)||19||Not reported|
|(Distribution System |
(3 years of data only)
|DAFB Annual Consumer Reports (For All DAFB wells)1|
|1998||14 (11/98)||10 (11/98)|
|1999||14 (11/98)||10 (11/98)|
|2000||Below 50 ppb, therefore level not reported||10 (11/98)|
|2001||Below 50 ppb, therefore level not reported||710 (8/01)|
Sources: AFIERA 2001, DAFB 1998, 1999, 2000, 2001a
1 Arsenic, like other inorganic compounds, is sampled every 3 years. The concentration represents the maximum arsenic concentration detected for the year sampled.
|Well ID||Year Sampled||TCE||cis-1,2-DCE||PCE||Vinyl Chloride||Number of Samples|
Well not installed until 1996
Source: Dames & Moore 2001; DAFB/CEV 2003.
Note: DM397D was also sampled in 1999-2002, but no contaminants were detected. The well was not sampled in 2003 because it was damaged.
Key: 1,2-DCE=1,2-dichloroethylene; ND=not detected; NR=not reported; PCE=tetrachloroethylene; TCE = trichloroethylene.