HEALTH CONSULTATION
Past Exposure to Drinking Water From On-Base Wells 313 and 314
KELLY AIR FORCE BASE
SAN ANTONIO, BEXAR COUNTY, TEXAS
Table 1. Production/Drinking Water Well Information, Kelly Air Force Base.
New Well Number (Same as Building Number) | Old Base Well Number | "I" Series Well Number | USGS Well Number | Year Drilled | Date Plugged | Total Depth (feet) | Max* (gpm) | Production for 7/88 (1000 gallons) |
Comment |
81 | - | - | - | 1994 | na | 1,500 | 2,200 | 0 |
Replacement for wells 141 and 313.
|
141 | 3 | 96 | 810 | 1906 | 6/20/91 | 1,400 | 900 | 0 |
Out of service since 1984.
|
313 | 2 | 124 | 808 | 1910 | 6/26/91 | 1,590 | 1,050 | 36,535 |
7/7/88: 5.5 µg/L PCE detected.
9/23/88: No VOCs detected. 1/31/89: Well 313 is taken out of service. 6/23/89: Horizontal pipe found with 52 µg/L PCE. 7/17/89: Gap in well at 590 feet. 3/26/91: Determined pipe comes from shallow aquifer. 6/26/91: Plug placed in pipe over horizontal pipe. 6/16/91: Well 313 is cemented and permanently sealed. |
314 | 4 | 97 | 809 | 1940 | 6/21/98 | 1,608 | 1,500 | 28,289 |
7/7/88, 8/11/88, 9/23/88, 7/14/89, 9/6/89,
10/12/89: No contaminants detected.
2/1/90: Detected very low levels of chlorinated solvents. 3/6/90: Horizontal pipe found. 4/11/90: A patch is placed over the horizontal pipe as a precaution. 6/21/98: Well is cemented and sealed. |
1040 | - | - | - | 1996 | na | 1,560 | 800 | 0 |
Replacement for well 1044.
|
1044 | 7 | 66 | 713 | 1924 | 12/19/96 | 1,677 | 550 | 13,627 |
Well plugged and replaced by well 1040.
|
1536 | 8 | 77 | - | 1943 | na | 1,042 | 650 | 13,338 |
--
|
1556 | 6 | 78 | 806 | 1943 | 1/23/97 | 1,030 | 700 | 15,024 |
Well plugged and replaced by well 2047.
|
1638 | 5 | 123 | 805 | 1940 | na | 1,632 | 1,600 | 12,864 |
--
|
1761 | - | - | - | not known | na | 1,460 | 1,500 | 0 |
Under design. Replacement for well 314.
|
2047 | - | - | - | - | na | 505 | 2,200 | 0 |
Replacement for wells 314 and 1556.
|
3010 | - | - | - | 1919 | na | 1,120 | 1,300 | 6,327 |
--
|
Note: The production wells draw water from the Edwards aquifer. All production wells feed into a closed loop distribution system. The water is used exclusively for the base--both military and civilian personnel. Since 1983, the base's population ranged from a low of 19,021 in 1995 to a high of 24,830 persons in 1999, with 21,961 persons in 1988. Information compiled by Air Force personnel suggests that the average stay on base is approximately 2 years for officers and 3 years for enlisted personnel.
Table 2. Irrigation Wells at Kelly Air Force Base.
"I" Series Well Number | Year Drilled | Date Plugged | Comment |
65 | 1912 | See Comment |
Inactive and abandoned. Kelly AFB could
not locate this well and records do not exist. May be covered by Taxiway
3B.
|
69 | 1924 | 1996 |
No comments.
|
72 | Possibly in the 1930s | 1997 |
No comments.
|
73 | 1933 | 1997 |
No comments.
|
74 | Unknown | 1998 |
No comments.
|
75 | Early 1930s | Unknown |
Abandonment confirmed by Kelly AFB in
1996
|
76 | 1913 | Unknown |
Abandonment confirmed by Kelly AFB in
1996.
|
80 | <1934 | Unknown |
Abandonment confirmed by Kelly AFB in
1996.
|
99 | 1912 | 1996 |
No comments.
|
Table 3. Production/drinking Water Well Monitoring data (1983 -1998)1, Volatile Organic Compound Concentration by Production Well, Kelly Air Force Base.
Chemical | Well 141 | Well 313 | Well 314 | Well 1044 |
Well 1536 | Well 1556 | Well 3010 | Well 1638 | EPA MCL or LTHA (µg/L) | EPA RBCs (6 Years of Exposure at 1/100,000) (µg/L) |
1,2-Dichloroethane | 0.3 - 4.2 (2/6) |
3 - 43 (3/9; 1/1) |
nd (0/10) |
2.3 - 36 (2/12; 1/2) |
nd (0/11) |
3.5 - 4 (2/8) |
4.5 (1/12) |
nd (0/11) |
5 | 6 c 17 nc |
1,3-Dichlorobenzene | nd (0/6) |
nd (0/9) |
nd (0/9) |
305 (1/12; 1/1) |
nd (0/11) |
nd (0/8) |
nd (0/12) |
nd (0/11) |
600 LTHA | 17 nc |
1,4-Dichlorobenzene | nd (0/6) |
nd (0/9) |
nd (0/9) |
149 (1/12;1/1) |
nd (0/11) |
nd (0/8) |
nd (0/12) |
nd (0/11) |
75 | 24 c 1400 |
Benzene | nd (0/6) |
3.87 (1/9) |
3.37 (1/11) |
0.5 - 3.58 (2/12) |
4.22 (1/11) |
3.43 (1/8) |
3.72 (1/12) |
5.74 (1/11) |
100 | 21 c 11 nc |
Chlorobenzene | nd (0/6) |
nd (0/9) |
nd (0/11) |
435 (1/12; 1/1) |
nd (0/11) |
nd (0/8) |
nd (0/12) |
nd (0/11) |
no value | 39 nc |
2-Chloroethylvinyl ether | nd (0/6) |
nd (0/7) |
nd (0/7) |
0.3 (1/7) |
nd (0/6) |
nd (0/6) |
nd (0/7) |
nd (0/5) |
3540* | no value |
Chloroform | 0.4 - 3.8 (3/6) |
1 - 12 (2/9; 1/1) |
nd (0/11) |
1 - 6.7 (2/13) |
0.3 - 4.5 (2/12) |
1.4 - 21 (1/9) |
1.7-10 (3/12, 1/3) |
2.7 - 16 (3/11; 1/3) |
700 | 8 c 61 nc |
Ethylbenzene | nd (0/6) |
nd (0/9) |
nd (0/11) |
39 (1/12) |
nd (0/11) |
nd (0/8) |
nd (0/12) |
nd (0/11) |
5 | 1300 nc |
Methylene chloride | 0.5 - 1.6 (2/6) |
0.5 - 5 (2/9) |
2.1 (1/9) |
1.1 - 3.8 (2/11) |
1.7 - 2.3 (2/10) |
1.3 - 1.4 (2/8) |
1.3 (1/11) |
2.4 (1/11) |
5 | 215 c 1600 nc |
1,1,1,2-Tetrachloroethane | 0.08 (1/6) |
nd (0/9) |
4.7 (0/9) |
nd (0/12) |
nd (0/11) |
nd (0/8) |
nd (0/11) |
nd (0/11) |
no value | 21.5 c 180 nc |
Tetrachloroethene | nd (0/6) |
0.12 -5.5 (4/9) |
nd (0/10) |
0.2 (1/13) |
nd (0/7) |
nd (0/7) |
nd (0/8) |
nd (0/6) |
5 | 55 c 250 nc |
1,1,1-Trichloroethane | 1.8 (1/6) |
1.2 (1/9) |
2.7 (1/11) |
nd (0/12) |
2.5-2.6 (2/11) |
1-1.8 (3/8) |
2 (1/11) |
2.5 (1/11) |
200 | 790 nc |
1,1,2-Trichloroethane | nd (0/6) |
nd (0/9) |
0.6 (1/9) |
nd (0/12) |
nd (0/11) |
nd (0/8) |
nd (0/11) |
nd (0/11) |
5 | 10 c 24 nc |
Trichloroethene | nd (0/6) |
nd - 2.8 (2/9) |
nd (0/10) |
2.2 (1/13) |
nd (0/7) |
nd (0/6) |
nd (0/8) |
nd (0/5) |
5 | 80 c 35 nc |
c | Cancer |
nc | noncancer |
EPA RBCs | EPA Region 6 Risk Based Concentrations based on 30 years of exposure 24 hours a day, 350 days per year. |
LCRA | Lower Colorado River Authority |
LTHA | Lifetime Health Advisory for drinking water |
MCL | EPA's maximum contaminant level |
nd | not detected |
OEHL= | Occupational Environmental Health Laboratory |
µg/L= | Micrograms per liter |
TDH= | Texas Department of Health |
TNRCC= | (Texas Natural Resources and Conservation Commission) |
TWC= | Texas Water Commission |
(x/x)= | (number of detects/number of samples collected) |
(x/x)= | (number of detects above EPA Risk Based Concentration at 6 years of exposure at 1/100,000 risk/number of detects) |
* = | No human health based screening levels were available for 2-chloroethylvinyl ether. This value is the surface water screening values derived by U.S. EPA Region 4 Water Management Division. These values were obtained from Water Quality Criteria documents and represent the chronic ambient water quality criteria values for the protection of aquatic life. |
Table 4. Production/drinking Water Well Monitoring Data (1983 -1988), Volatile Organic Compound Concentration for Well 313, Kelly Air Force Base
Chemical | Organization Collecting and Analyzing Sample with Month and Year of Sample | |||||||||||
Sampling as part of the SDWA | Sampling as part of the IRP program | Sampling as part of the SDWA | ||||||||||
OEHL 11/83 |
OEHL 4/85 |
Radian 1/86 |
OEHL 1/86 |
OEHL 3/86 |
OEHL 3/86 (split) |
OEHL 4/86 |
OEHL 5/86 |
TDH 7/88 | TDH 9/88 |
EPA MCL or LTHA (µg/L) |
EPA RBCs (6 Years of Exposure at 1/100,000) (µg/L) |
|
1,2-Dichloroethane | ND | NS | ND | 43 | 3 | 2.1 | ND | ND | <1.0 | <1.0 | 5 | 6 c 17 nc |
1,3-Dichlorobenzene | ND | NS | ND | ND | ND | ND | ND | ND | <1.0 | <1.0 | 600 LTHA | 17 nc |
1,4-Dichlorobenzene | ND | NS | ND | ND | ND | ND | ND | ND | ND | <1.0 | 75 | 24 c 1400 |
Benzene | ND | NS | 3.87 | ND | ND | ND | ND | ND | <0.1 | <0.1 | 100 | 21 c 11 nc |
Chlorobenzene | ND | NS | ND | ND | ND | ND | ND | ND | <0.1 | <0.1 | no value | 39 nc |
Chloroform | ND | NS | ND | 12 | 1 | ND | ND | ND | <0.1 | <0.1 | 700 | 8 c 61 nc |
Ethylbenzene | ND | NS | ND | ND | ND | ND | ND | ND | <2.0 | <.2.0 | 5 | 1300 nc |
Methylene chloride | ND | NS | ND | 5 | 0.5 | ND | ND | ND | <0.1 | <0.1 | 5 | 215 c 1600 nc |
Tetrachloroethene | ND | NS | 0.34 | 0.6 | ND | ND | 0.12 | ND | 5.5 | <0.1 | 5 | 55 c 250 nc |
1,1,1-Trichloroethane | ND | NS | ND | ND | 2.1 | ND | ND | ND | <1.0 | <1.0 | 200 | 790 nc |
Trichloroethene | ND | NS | ND | 2.8 | ND | ND | ND | ND | <0.1 | <0.1 | 5 | 80 c 35 nc |
Source: Kelly AFB. | |
ND= | not detected |
NS = | not sampled |
µg/L = | micrograms per liter |
RBC= | risk based concentration |
SDWA = | Safe Drinking Water Act |
TDH= | Texas Department of Health |
OEHL= | Occupational Environmental Health Laboratory, U.S. Air Force |
LTHA = | U.S. EPA lifetime health advisory for drinking water |
IRP = | Installation Restoration Program |
Table 5. Production/drinking Water Well Monitoring Data (1983-1998), Volatile Organic Compound Concentration for Well 314, Kelly Air Force Base.
Chemical | Organization Collecting and Analyzing Sample with Month and Year of Sample | ||||||||||||||||
Sampling as part of the SDWA | Sampling as part of the IRP program | Sampling as part of the SDWA | |||||||||||||||
OEHL 11/83 |
OEHL 4/85 |
Radian 1/86 |
OEHL 1/86 |
OEHL 3/86 |
OEHL 3/86 (split) |
OEHL 4/86 |
OEHL 5/86 |
TDH 7/88 | TDH 9/88 |
2/90* | TWC /93 |
TDH 3/94 |
TDH 12/96 | TNRCC 2/12/98 | EPA MCL or LTHA (µg/L) |
EPA RBCs (6 Years of Exposure at 1/100,000) (µg/L) |
|
1,2-Dichloroethane | <.0.3 | NS | ND | ND | ND | ND | ND | ND | <0.001 | <0.001 | ND | NS | <0.5 | NS | <0.5 | 5 | 6 c 17 nc |
1,3-Dichlorobenzene | ND | NS | ND | ND | ND | ND | ND | ND | NS | NS | ND | NS | <1.0 | NS | <0.5 | 600 LTHA | 17 nc |
1,4-Dichlorobenzene | 75 | NS | ND | ND | ND | ND | ND | ND | ND | NS | ND | NS | <0.5 | NS | <0.5 | 75 | 24 c 1400 |
Benzene | ND | NS | 3.37 | ND | ND | ND | ND | ND | <0.001 | <0.001 | ND | NS | <0.5 | NS | <0.5 | 100 | 21 c 11 nc |
Chlorobenzene | ND | NS | ND | ND | ND | ND | ND | ND | <0.001 | <0.001 | ND | NS | <0.5 | NS | <0.5 | no value | 39 nc |
Chloroform | ND | ND | ND | 17 | ND | ND | ND | ND | NS | <0.001 | ND | NS | <0.5 | NS | <0.5 | 700 | 8 c 61 nc |
Ethylbenzene | ND | NS | ND | ND | ND | ND | ND | ND | <0.002 | <0.002 | ND | NS | <0.5 | NS | <0.5 | 5 | 1300 nc |
Methylene chloride | ND | NS | ND | ND | 2.1 | ND | ND | ND | NS | NS | ND | NS | <0.5 | NS | <0.5 | 5 | 215 c 1600 nc |
1,1,1,2-Tetrachloroethane | ND | NS | ND | ND | ND | ND | ND | ND | NS | NS | 4.7 | NS | NS | NS | <0.5 | no value | 21.5 c 180 nc |
Tetrachloroethene | <0.2 | NS | ND | ND | ND | ND | ND | ND | <0.001 | <0.001 | ND | NS | NS | NS | <0.5 | 5 | 55 c 250 nc |
1,1,1-Trichloroethane | ND | NS | ND | ND | 2.1 | ND | ND | ND | <0.001 | <0.001 | ND | NS | <0.5 | NS | <0.5 | 200 | 790 nc |
1,1,2-Trichloroethane | ND | NS | ND | ND | ND | ND | ND | ND | NS | NS | 0.6 | NS | NS | NS | <0.5 | 5 | 10 c 24 nc |
Trichloroethene | ND | NS | ND | ND | ND | ND | ND | ND | <0.001 | <0.001 | ND | NS | NS | NS | <0.5 | 5 | 80 c 35 nc |
Source: Kelly AFB no date. | |
ND= | not detected |
NS = | not sampled |
OEHL= | Occupational Environmental Health Laboratory U.S. Air Force |
µg/L = | Micrograms per liter |
LTHA = | U.S. EPA lifetime health advisory for drinking water |
RBC= | risk based concentration |
TDH= | Texas Department of Health |
TNRCC = | (Texas Natural Resources and Conservation Commission) |
TWC = | Texas Water Commission |
* = | Organization collecting and analyzing sample not reported (Gargiulo 1998). |
IRP = | Installation Restoration Program |
SDWA = | Safe Drinking Water Act |
Table 6. Production/drinking Water Well Monitoring Data (1983 -1995), Volatile Organic Compound Concentration (µg/L) for Well 1044, Kelly Air Force Base.
Chemical | Organization Collecting and Analyzing Sample with Month and Year of Sample | ||||||||||||||
Sampling as part of the SDWA | Sampling as part of the IRP program | Sampling as part of the SDWA | |||||||||||||
OEHL 11/83 |
Radian 1/86 |
OEHL 1/86 |
OEHL 3/86 |
OEHL 3/86 (split) |
OEHL 4/86 |
OEHL 5/86 |
TDH 7/88 | TDH 12/93 |
TDH 3/94 |
TDH 7/94 | LCRA 8/95 |
LCRA 11/95 |
EPA MCL or LTHA (µg/L) |
EPA RBCs (6 Years of Exposure at 1/100,000) (µg/L) |
|
1,2-Dichloroethane | <0.3 | ND | 36 | 2.3 | ND | ND | ND | <1.0 | NS | <0.5 | <0.5 | <0.5 | <0.5 | 5 | 6 c 17 nc |
1,3-Dichlorobenzene | ND | ND | 305 | ND | ND | ND | ND | <1.0 | NS | <1.0 | <1.0 | <0/5 | <0.5 | 600 LTHA | 17 nc |
1,4-Dichlorobenzene | ND | ND | 149 | ND | ND | ND | ND | <1.0 | NS | <0.5 | <0.5 | <0.5 | <0.5 | 75 | 24 c 1400 |
Chlorobenzene | ND | ND | 435 | ND | ND | ND | ND | <0.1 | NS | <0.5 | <0.5 | <0.5 | <0.5 | 100 | 21 c 11 nc |
2-Chloroethylvinyl ether | 0.3 | ND | ND | ND | ND | ND | ND | NS | NS | NS | NS | NS | NS | 3540* | no value |
Chloroform | ND | ND | 6.7 | 1 | trace | ND | ND | <0.1 | NS | 0.5 | <0.5 | <0.5 | <0.5 | 700 | 8 c 61 nc |
Ethylbenzene | ND | ND | 39 | ND | ND | ND | ND | <2.0 | NS | <0.5 | <0.5 | <0.5 | <0.5 | 5 | 1300 nc |
Methylene chloride | ND | ND | 3.8 | 1.1 | ND | ND | ND | NS | NS | <0.5 | <0.5 | <0.5 | <0.5 | 5 | 215 c 1600 nc |
Tetrachloroethene | ND | ND | 0.2 | ND | ND | ND | ND | <0.1 | <0.1 | <0.5 | <0.5 | <0.5 | <0.5 | 5 | 55 c 250 nc |
1,1,1-Trichloroethane | ND | NS | ND | ND | 2.1 | ND | ND | <1.0 | NS | <0.5 | <0.5 | <0.5 | <0.5 | 200 | 790 nc |
Trichloroethene | ND | ND | 2.2 | ND | ND | ND | ND | <0.1 | <0.1 | <0.5 | <0.5 | <0.5 | <0.5 | 5 | 80 c 35 nc |
ND= | not detected |
NS = | not sampled |
OEHL= | Occupational Environmental Health Laboratory |
µg/L = | micrograms per liter |
SDWA = | Safe Drinking Water Act |
TDH= | Texas Department of Health |
TNRCC = | (Texas Natural Resources and Conservation Commission) |
TWC = | Texas Water Commission |
IRP = | Installation Restoration Program |
* = | No human health based screening levels were available for 2-chloroethylvinyl ether. This value is the surface water screening values derived by U.S. EPA Region 4 Water Management Division. These values were obtained from Water Quality Criteria documents and represent the chronic ambient water quality criteria values for the protection of aquatic life. |
Table 7. Selected history of Wells 313 and 314, Kelly Air Force Base.
Date | Well | Event |
11/83 | 313 and 314 | Kelly Air Force Base (KAFB) sampled Wells 313 and 314 and analyze them for VOCs for the first time. No contaminants were measured above detection limits. |
4/85 | 313 and 314 | KAFB sampled Wells 313 and 314 for selected compounds; no contaminants were measured above detection limits. |
1/22/86 | 313 and 314 | KAFB sampled Wells 313 and 314. Samples are analyzed by the Air Force's Occupational Environmental Health Laboratory and Radian Corporation under contract to the Air Force. Several compounds are detected but are not above MCLs. |
3/11/86 | 313 and 314 | KAFB sampled Wells 313 and 314. Samples are split and both samples are analyzed by the Air Force's Occupational Environmental Health Laboratory. Several compounds are detected but are not above MCLs. |
4/16/86 | 313 and 314 | KAFB conducted routine sampling in accordance with the EPA Safe Drinking Water Act (SDWA); no contaminants were detected above detection levels except for tetrachloroethene in Well 313 at at 0.12µg/L. |
5/15/86 | 313 and 314 | KAFB sampled Wells 313 and 314; no contaminants were detected above detection levels. |
07/07/88 | 313 and 314 | TDH conducted sampling. In the sample from Well 314, no contaminants are measured above detection limits. In the sample from Well 313, 5.5 µg/L of tetrachloroethene (PCE) is detected, which exceeds the MCL. During the month of July, this well contributes less than 30 percent of the total water distributed by the base water distribution system. |
08/11/88 | 313 and 314 | KAFB sampled the two wells. PCE was not measured above the detection limit (<0.1 µg/L). |
09/23/88 | 313 and 314 | TDH conducted confirmation sampling of the two wells, and no contaminants were measured above detection limits. No corrective action was required under the SDWA. |
01/31/89 | 313 | KAFB took Well 313 out of service to repair the pump; use of the well was never resumed. |
06/23/89 | 313 | In response to the sound of running water
in the well casing on 6/22/89, a TV study was conducted and revealed a 12"
diameter horizontal pipe about 30 feet deep running into the well's casing
at 31 feet below ground level. The pipe was formerly used to convey water
under artesian pressure from the well to a distribution system located between
Wells 313 and 314; during the 1970s, pumps were installed in the two wells,
and the distribution system was shut down and associated pipes reportedly
capped.
A sample of the water running from this pipe was collected; results revealed that it contains 52 µg/L of PCE. However, this concentration is not considered precise because of the way the instruments used were calibrated. Levels of other chlorinated solvents were not measured in the sample. Metal levels were below detection limits. No information about how long the pipe has been present or how it was used is available. |
06/26/89 | 313 | KAFB has a three-foot plug placed in front of the horizontal pipe to prevent water in the pipe from entering the production well. |
07/14/89 | 314 | KAFB sampled Well 314 for parameters that include VOCs, and no contaminants were measured above detection limits. |
07/17/89 | 313 | An additional TV study shows a one-foot gap in the well at a depth of 590 feet. |
09/01/89 | 313 | A letter from "MFR" raises questions about the source of contamination in Well 313 and whether contamination might be a problem elsewhere in the base's water supply system. |
09/06/89 | 314 | KAFB samples Well 314 for metals and related parameters; no constituents were detected at levels of concern. |
10/12/89 | 314 | KAFB samples Well 314 for parameters that include VOCs, and no contaminants are measured above detection limits. |
10/13/89 | 313 | Fuel contamination was reported in an IRP monitoring well near Well 313. |
02/01/90 | 314 | Samples collected from Well 314 do not contain detectable concentrations of any regulated analytes, but certain chlorinated solvents were detected at low levels, below or slightly exceeding ATSDR's most conservative comparison values. |
03/06/90 | 314 | a horizontal pipe similar to the one discovered entering Well 313 was reported present in this well. Although no water is observed entering the well from the pipe, it is not known whether this may have occurred in the past. |
04/11/90 | 314 | Installation of a patch to prevent water in the horizontal pipe from entering this production well was completed. |
03/26/91 | 313 | KAFB concluded that the water in the horizontal pipe was coming from the shallow alluvial aquifer. |
06/16/91 | 313 | Well 313 is cemented and permanently sealed. |
06/21/98 | 314 | This well is permanently sealed. |
Key: KAFB = Kelly Air Force Base; MCL = EPA's maximum contaminant level; SDWA = Safe Drinking Water Act; TDH = Texas Department of Health;
Table 8. Well Production for 1983 and 1984 in 1000 gallons.1
Well Production in 1983 per 1000 gallons | ||||||||
Well Number | 313 | 141 | 314 | 1638 | 1556 | 1044 | 3010 | 1536 |
January | 3210 | 27108 | 42405 | 0 | 1272 | 9055 | 15639 | 0 |
February | 1446 | 28836 | 38742 | 0 | 10776 | 6600 | 2952 | 0 |
March | 692 | 31455 | 36969 | 0 | 23472 | 8183 | 4056 | 0 |
April | 819 | 32395 | 32091 | 0 | 22560 | 12845 | 14340 | 0 |
May | 2172 | 33939 | 35132 | 0 | 16464 | 12206 | 22269 | 0 |
June | 28126 | 24408 | 22454 | 0 | 22704 | 11513 | 17316 | 0 |
July | 32975 | 30159 | 15103 | 0 | 23520 | 12659 | 18681 | 0 |
August | 30677 | 33696 | 24259 | 0 | 27024 | 13541 | 16731 | 0 |
September | 34551 | 10470 | 27521 | 0 | 23376 | 12735 | 24258 | 0 |
October | 38177 | 5130 | 29132 | 0 | 16824 | 13834 | 20358 | 0 |
November | 28440 | 20898 | 17696 | 0 | 16272 | 4176 | 19656 | 0 |
December | 29021 | 19431 | 18288 | 0 | 17634 | 264 | 19278 | 0 |
|
||||||||
Annual total | 230306 | 297925 | 339792 | 0 | 221898 | 117611 | 195534 | 0 |
Average per month | 19192 | 24827 | 28316 | 0 | 18492 | 9801 | 16294 | 0 |
Average gallons per minute | 437 | 565 | 645 | 0 | 421 | 223 | 371 | 0 |
Ratio 313/314 |
0.68 |
Well Production in 1984 per 1000 gallons | ||||||||
313 |
141 |
314 |
1638 |
1556 |
1044 |
3010 |
1536 |
|
January | 33741 | 20637 | 10911 | 0 | 16828 | 1574 | 7227 | 11104 |
February | 29452 | 16838 | 10068 | 0 | 10549 | 5185 | 5432 | 11961 |
March | 34412 | 27290 | 17658 | 0 | 8120 | 11570 | 5685 | 7478 |
April | 33967 | 28133 | 25401 | 0 | 8515 | 13135 | 9459 | 8726 |
May | 38015 | 34398 | 28465 | 0 | 8841 | 11014 | 11108 | 15792 |
June | 38019 | 36805 | 32150 | 0 | 17003 | 11551 | 14908 | 5696 |
July | 39808 | 37044 | 32992 | 0 | 11426 | 14797 | 33933 | 0 |
August | 36057 | 36045 | 30060 | 0 | 13696 | 14951 | 18262 | 17016 |
September | 37247 | 25723 | 17527 | 11760 | 6660 | 12482 | 11054 | 15875 |
October | 37053 | 10071 | 19805 | 22419 | 7638 | 4639 | 1595 | 12734 |
November | 33719 | 0 | 16343 | 16416 | 14072 | 8333 | 14615 | 2613 |
December | 33125 | 0 | 25643 | 11090 | 11716 | 3378 | 8089 | 15913 |
Total | 424615 | 272984 | 267023 | 61685 | 135064 | 112609 | 141367 | 124908 |
Average per month | 35385 | 22749 | 22252 | 5140 | 11255 | 9384 | 11781 | 10409 |
Average gallons per minute | 806 | 518 | 507 | 117 | 256 | 214 | 268 | 237 |
Ratio 313/314 |
1.59 |
1 ATSDR obtained and reviewed the production well data for years 1983 through 1988. 1983 was the year Kelly AFB began sampling the wells and 1988 is the year that Well 313 was discontinued. The production volumes change from year to year so the calculated concentrations would also change depending on the relative production from Wells 313 and 314. For the calculated concentrations, ATSDR used the values that produced the highest concentrations to be more protective of public health in this evaluation. In these cases, 1983 produced the highest concentrations in the calculations in Appendix C-1 and 1984 produced the highest concentrations in the calculation in Appendix C-2.
Table 9. Pathway Table; Summary of Exposure Pathway Elements.
Situation Name | Contaminants | Exposure Pathways Elements | Dates and Duration of Exposure | Comments | ||||
Source | Environmental Media | Point of Exposure | Route of Exposure | Exposed Population | ||||
Exposure to Water from Wells 313 and 314 | 1,2-dichloroethane, benzene, chloroform, ethylbenzene, methylene chloride, 1,1,1,2-tetrachloroethane, tetrachloroethene, 1,1,2-trichloroethane, and trichloroethene |
Shallow groundwater | Water | Water taps, faucets, and spigots throughout the base. | Ingestion, inhalation, dermal contact | A subgroup of civilian and military personnel and families on-base. Population estimates from 1983 to 1990 vary from 23,000 to 29,000 per year. Potential exposed population is estimated at 14,000. | Past, maximum estimates are about six years, from late 1983 to early 1990. | No Apparent Public Health Hazard |
Figure 2. Wells in Bexar County, based on the well inventory from the Texas Water Development Board
Screening values were obtained from U.S. EPA Region 6 (http://www.epa.gov/region06/6pd/rcra_c/pd-n/screen.htm) and modified to site-specific exposure conditions and risk levels. Only cancer screening values were modified. EPA Region 6 cancer screening values are based on 30 years exposure as an adult and a target risk of 1/1,000,000. ATSDR modified the cancer screening values to 6 years and target risk of 1/100,000 by multiplying the screening values by 50; 5 for the conversion from 30 to 6 years and 10 for the conversion from 1/1,000,000 to 1/100,000. The 6 years is based on the 6 years of exposure discussed in the Data Evaluation and Interpretation Section of this consultation. Because the U.S. EPA Region 6 cancer screening values were based on 6 years as a child and 24 years as an adult, the conversion includes child and adult exposures. The conversion from 1/1,000,000 to 1/100,000 is based on the following ATSDR cancer risk categories in which 1/100,000 is considered no apparent increased risk of cancer as shown below.
Category Definitions of Cancer Risk
Category | Fraction | Decimal | Exponential |
No Increased Risk | <1/100,000 | <0.00001 | <1E-05 |
No Apparent Increased Risk | 1/100,000 | 0.00001 | 1E-05 |
Low Increased Risk | 1/10,000 | 0.0001 | 1E-04 |
Moderate Increased Risk | 1/1,000 | 0.001 | 1E-03 |
High Increased Risk | 1/100 | 0.01 | 1E-02 |
Very High Increased Risk | >1/100 | >0.01 | >1E-02 |
Well 1044 exceeded MCLs one time in January 1986. A second sample collected in January 1986 and subsequent samples collected in March and April of 1986 from this well did not exceed the MCL. In five subsequent samples from the well, collected July 1988 through November 1995, volatile organic compounds were not detected (See Table 6).
Kelly AFB investigated the inconsistency of the sampling results from Well 1044 and other wells sampled in 1986. They concluded that the following errors occurred in the sampling protocol:
Because the levels exceeding the MCLs only occurred once and may have been erroneous, ATSDR considered the January 1986 samples not to be representative of the water in the well and not a health hazard.
Appendix C-1. Calculation of concentration in water combined from Wells 313 and 314 using 1984 production data because it provides the highest concentrations for this calculation.
Chloroform
806 gpm (12 µg/L) + 507 gpm (1* µg/L) = 7.8 µg/L
806 gpm + 507 gpm
1,2-Dichloroethane
806 gpm (43 µg/L) + 507 gpm (1* µg/L) = 26.8 µg/L
806 gpm + 507 gpm
Tetrachloroethene
806 gpm (5.5 µg/L) + 507 gpm (1* µg/L) = 3.8 µg/L
806 gpm + 507 gpm
* When not reported, 1 µg/L is assumed to be the detection limit.
Appendix C-2. Calculation of concentration of well water with shallow aquifer water at 100 µg/L and 10 µg/L flowing into the well at 10 gpm and 50 gpm, using 1983 production data because it provides the highest concentrations for this calculation.
• Water from Well 313 combining with water from the shallow aquifer at 10 gpm
(1 µg/L x (437 gpm-10 gpm)) + (100 µg/L x 10 gpm) = 3.26
µg/L tetrachloroethene
437 gpm
(1 µg/L x (437 gpm-10 gpm)) + (10 µg/L x 10 gpm) = 1.21 µg/L
trichloroethene
437 gpm
• Combining with Well 314
437 gpm (3.26 µg/L) + 645 gpm (1 µg/L) = 1.92 µg/L tetrachloroethene
437 gpm + 645 gpm
437 gpm (1.21 µg/L) + 645 gpm (1 µg/L) = 1.19 µg/L trichloroethene
437 gpm + 645 gpm
• Water from Well 313 combining with water from the shallow aquifer at 50 gpm
(1 µg/L * (437 gpm-50 gpm)) + (100 µg/L * 50 gpm) = 12.3
µg/L
&nb