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PUBLIC HEALTH ASSESSMENT

DOVER AIR FORCE BASE
DOVER, KENT COUNTY, DELAWARE


TABLES (Cont.)

Table 2.

Evaluation of Exposure Pathways at DAFB
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
Current
Future
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
Current
Future
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
Current
Future
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
Current
Future
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.


Table 3.

Contaminant Concentrations in Off-Site Water Supply Wells
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.


Table 4.

Chronological Summary of Monitoring Activities at Off-Site Water Supply Wells
Date Activity
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.


Table 5.

Area 5 Contamination
Site Source VOCs BTEX
On-Base Source
OT51 Former maintenance hangars Bldgs. 794, 789, 790, and 791 1,2-DCE
Vinyl chloride
 
SS20 Near Bldg. 639 PCE  
OT41 IWCD, near the motor pool TCE
1,2-DCE
 
OT43 Minor source. Oil/water separator recommended for NFA.   BTEX
OT44 An oil/water separator TCE
1,2-DCE
 
Off-Base Source
Paradee Gulf Station     BTEX
P&F Motorcycle Shop   PCE and TCE  

Source: Dames & Moore 2001.


Table 6.

DAFB Drinking Water Supply
Well Year Drilled Aquifer Comment
A   Cheswold Replaced in 1993 due to "pulling sand"
B 1953 Cheswold  
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.
HA-1 Unknown Piney Point  
HA-2 1979 Piney Point  

Source: DAFB undated, DAFB 2003.


Table 7.

Maximum Arsenic Concentration (ppb) in DAFB Drinking Water Supply, 1980-2001
Year Maximum Arsenic Concentration (ppb)
Main Base and Eagle Heights Wells
(sample date)
Eagle Meadow Wells
(sample date)
AFIERA 2001
1980-2001 (Well D only) 19 Not reported
(Distribution System
(3 years of data only)
6.5 Not reported
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 7–10 (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.


Table 8.

TCE and cis-1,2-DCE Concentrations in Deep Columbia Aquifer Monitoring Wells Located in the Eagle Heights Housing Area, 1993–2003
Well ID Year Sampled TCE cis-1,2-DCE PCE Vinyl Chloride Number of Samples
DM350D 1993 0.6 0.6 ND NR 1
1995 ND ND ND ND 2
1996 ND ND ND ND 3
1997 ND ND ND ND 3
1998 ND ND ND ND 4
1999 6.1 ND ND ND 4
DM353D 1993 660 740 NR NR 1
1995 2,400-2,600 2,300-2,600 69-84 22-23 2
1996 2,400-3,000 2,500-3,100 72-110 27-28 3 (2)
1997 3,000-3,300 3,600-3,800 130-160 25-43 3
1998 3,000-3,200 4,100-4,830 170-200 44-367 3
1999 3,100 3,300 190 ND 1
2000 2,700-3,000 3,900-4,700 150-210 75-110 2
2001 2,900-3,200 5,100-5,200 240-250 150-200 2
2002 2,600 5,900 230-250 270-280 2
2003 3,700 7,500 300 220 1
DM354D 1993 580 36 NR NR 1
1995 740-770 47-52 ND ND 2
1996 740-770 54-71 ND ND 2
1997 760-1,000 76-100 ND ND 3
1998 1,000-1,400 110-199 3 6-12 3
1999 1,800 120 ND ND 1
2000 1,800-2,500 240-280 6-9 6.8-7 2
2001 2,600-3,300 320-380 8-14 8-11 2
2002 1,200-1,400 190-200 ND-4 ND-7.2 2
2003 2,800 410 9.1 12 1
DM355D 1993 2 ND NR NR 1
1995 86-150 6-11 ND ND 2
1996 210 16 ND ND 1
1997 270-330 34-41 ND ND 3
1998 245-470 32-46 ND ND 3
1999 800 70 ND ND 1
2000 870-900 62-76 ND-2.3 ND 2
2001 690-1,000 61-88 3-5 ND 2
2002 530-1,200 61-190 ND-4 ND-7.2 3
2003 1,200 120 6.2 NR 1
DM360D 1995 110-150 ND ND ND 3
1996 100-110 ND ND ND 2
1997 87-92 ND ND ND 3
1998 42-100 0.6 ND ND 3
1999 79 ND ND ND 1
2000 38-47 ND ND ND 2
2001 53-54 1-2 ND ND 2
2002 28-42 1.5-2 ND-0.32 ND 2
2003 77 3.6 0.72 ND 1
IRO6D
Well not installed until 1996
1996 220 56 6 ND 1
1997 260-340 80-120 5-7 ND 3
1998 267-340 130-174 5-8 ND-4 3
1999 370 160 7 ND 1
2000 550-650 260-310 9.4-11 ND-5.5 2
2001 620-740 340-390 12-13 14-15 2
2002 560-590 400-450 12-15 13-15 2
2003 810 570 17 20 1
IRO7D 1996 860 1,000 13-15 60 1
1997 720-840 750-960 11-12 48-63 3
1998 504-890 970-1,100 14-19 65-596 3
1999 720 1,300 36 110 1
2000 460 610-1,500 22-46 92-120 2
2001 380-460 1,500-1,800 47-58 160-170 2
2002 360-460 1,200-1,300 32-35 120-140 2
2003 480 1,800 77 170 1

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.


FIGURES

Area Map
Figure 1. Area Map

Site Map


Figure 2. Site Map

Exposure Pathway Figure
Figure 3. Exposure Pathway Figure

Demographics within a 1-Mile Buffer of Dover Air Force Base
Figure 4. Demographics within a 1-Mile Buffer of Dover Air Force Base

Area 5 Plume and Off-Base Wells
Figure 5. Area 5 Plume and Off-Base Wells

Location of LF26, Ball Fields, and Schools
Figure 6. Location of LF26, Ball Fields, and Schools



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