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The Agency for Toxic Substances and Disease Registry has concluded the levels of contaminantsdetected at on- and off-site locations associated with East Kelly Air Force Base are not likely tocause adverse health effects. The current site conditions do not pose a public health threat.Contaminated surface soil at East Kelly was evaluated to determine if chemicals at levels of healthconcern could migrate off-site via stormwater runoff or wind-blown dust. Soil gas samples werealso evaluated to determine if residents near East Kelly are being exposed to the volatile organiccompounds that may get into their homes from the contaminated shallow groundwater. The on-sitesoil contamination does not pose a health threat to residential areas because of the low levels ofcontaminants detected. A review of volatile organic compounds in soil gas and indoor air modelingsuggests that the shallow aquifer contamination does not pose a threat to human health sincecontaminants are not getting into residences at levels of health concern. There were no private wellowners identified near East Kelly using the contaminated shallow groundwater for domesticpurposes.


The East Kelly area is an annex located east of Kelly Air Force Base and has historically been usedfor aircraft maintenance and hazardous waste storage and transport. Leakage, spillage, andlandfilling of these wastes have occurred throughout East Kelly and consequently contaminated theshallow groundwater and soil. The shallow groundwater is contaminated with chlorinated solventsand has migrated east and southeast into the surrounding community. The surface soil at East Kellyhas been contaminated primarily with polyaromatic hydrocarbons (PAHs). Community memberssuspect contaminants in the shallow groundwater are getting into their homes through soil gas andcausing adverse health effects. The Agency for Toxic Substances and Disease Registry (ATSDR)was initially petitioned by the late Congressman Frank Tejeda to evaluate the potential publichealth impact of contaminants released from Kelly Air Force Base and later requested to evaluateEast Kelly [1]. ATSDR completed a public health assessment for Kelly Air Force Base in 1999.The purpose of this public health assessment is to identify potential human exposures to substancesrelated to East Kelly activities by evaluating existing on- and off-site environmental data,community health concerns, and to recommend appropriate public health follow-up activities.

Site Background

Kelly Air Force Base was commissioned in 1916 in Bexar County, Texas, approximately sevenmiles southwest of San Antonio. East Kelly (also called Zone 4) is a storage area comprising about400 acres along the eastern edge of Kelly Air Force Base. The surrounding community is a mixtureof residential, commercial, and light industrial areas (Appendix A, figure 1). In 1982, a restorationprogram was initiated to investigate and clean up hazardous waste at Kelly Air Force Base. Thisinvestigation determined that in addition to groundwater contamination from the main Kelly AirForce Base flowing southeast of East Kelly, leaking industrial waste pipe lines in the northernportion of East Kelly were also sources of environmental contamination. From the 1940s to themid-1970s, engine repair facilities at East Kelly used a collection system to transport chemicalwastes to a central location for disposal. Over the years, this network of underground wastecollection pipe lines leaked, contaminating shallow groundwater with waste oils, solvents, andpaint thinners [2]. Other wastes stored at East Kelly in the past contained herbicides, metals, PAHs, and volatile organic compounds (VOCs).


Specific health concerns expressed by community members pertaining to East Kelly are the releaseof soil gas into nearby homes from contaminated shallow groundwater and the possibility ofcontaminated soil found on-site reaching their homes by stormwater runoff. Residents are alsoconcerned that contaminants from Kelly Air Force Base are causing a number of illnessesincluding: cancer, immune system disorders, nervous system disorders, birth defects, liverproblems, skin problems, respiratory illnesses, muscular problems, nosebleeds, and headaches.These health concerns were addressed in the Kelly Air Force Base public health assessment whichwas released in 1999. In this public health assessment, ATSDR evaluates the environmentalcontamination related to East Kelly to identify any additional impact for these same health concerns.


There are 5,021 people living within a one mile radius of East Kelly (Appendix A, figure 1) [3].The entire population is Hispanic. Of the total population, 18% are under age 6 and 27% are age 65years and older. In 1990, there were about 900 females of reproductive age (15-44 years) in the area.


  1. Methods

Evaluation Methods

The following sections contain an evaluation of the environmental data available for East Kelly. Inpreparing this evaluation, ATSDR uses established methodologies for determining how peoplemay be exposed to potential contamination related to East Kelly and what harmful effects, if any,may result from such exposure. Exposure pathways (or routes of physical contact with chemicals)that ATSDR evaluates are ingestion, inhalation, and skin contact. ATSDR uses comparison values(CVs), which are screening tools used to evaluate environmental data that are relevant to theexposure pathways. Comparison values are concentrations of contaminants that are considered safelevels of exposure. Chemicals detected below CVs are not likely to represent a health concern;chemicals that are detected above CVs require a more detailed evaluation of site specific exposureconditions. ATSDR also evaluates the public health implications of exposures to combinations ofsubstances that may be present in one or more environmental media to which populations may beexposed. For a complete discussion of these criteria (quality assurance considerations, humanexposure pathway analyses, health-based comparison values, and the methods of selectingcontaminants above comparison values), refer to Appendix B.

  1. Extent of Contamination


East Kelly lies over a shallow aquifer and a deeper, confined aquifer, the Edwards Aquifer. Theshallow aquifer is at depths below the surface ranging from approximately 15 to 30 feet. Theleaking industrial waste lines at East Kelly contaminated the shallow aquifer with VOCs and PAHs[4]. There is a layer of clay below the shallow aquifer ranging from 50 to 450 feet in thickness.Under the clay layer is about 300 feet of a loose, crumbly rock material called marl and another500 feet of limestone and shale. The Edwards aquifer is below about 1000 feet of clay, marl,limestone, and shale layers [5]. Most residences near East Kelly receive drinking water from BexarMetropolitan Water District, a municipality that obtains its water from the Edwards Aquifer. Thereis one residence near East Kelly that has a private well used for drinking water (discussed in the next section Private Wells).

Private Wells

Municipal water has been supplied to residents east of Kelly AFB beginning in the 1950s [6].Three private well surveys conducted in 1988, 1996, and 1998 (Appendix A, figure 2) identified 22 shallow aquifer private wells within a one mile radius of Kelly AFB [7] [8]. Most of the privatewells identified were using groundwater from the shallow aquifer for gardening or lawn care.However, one private well on Quintana Road was identified as a drinking water source in 1988.Four private wells were dry or blocked by debris. Water samples from the remaining 18 usableprivate wells were collected and analyzed for VOCs, semi-volatile organic compounds (SVOCs),metals, and cyanide. Several contaminants were detected in the private well used for drinkingwater and were not at levels of health concern [9]. Several contaminants were also detected insome of the private wells not used for drinking water [8]. The chemicals detected in private wells are listed below:

Table 1.

Chemicals detected in the shallow aquifer private wells in 1988, 1996, and 1998
Chemical Range of Chemical Concentration (ppb) Number of Private Wells that Chemicals were Detected above Drinking Water Comparison Values1
Tetrachloroethene (PCE)ND-208
Trichloroethene (TCE)ND-827
Vinyl ChlorideND-101
1 1997 EPA Region III risk-based concentration for drinking water
ND = Not Detected
ppb = parts per billion

Residents near East Kelly have been notified of the shallow aquifer contamination and have beenadvised not to use water from their wells for consumption, showering, or cooking. Thecontaminants detected in the private well used for drinking water were not at levels of health concern.


Most of the functioning private shallow aquifer wells were used for irrigating or watering gardensin the past and may still be used for watering lawns and gardens. The contaminants detected in theprivate wells near East Kelly are mostly VOCs which are not easily taken up in plants and quicklyvolatilize during watering [10]. ATSDR evaluated the irrigation exposure pathway by comparingthe VOCs levels in groundwater used for watering lawns and gardens with showering using waterwith the same levels of VOCs [11]. Showering represents a more conservative scenario thanoutdoor watering; even with this scenerio, ATSDR determined the VOCs would evaporate during watering and are not at levels of health concern.

Surface Soil

Nearby residents are concerned that the contaminated surface soil left on-site may migrate intoresidential areas via stormwater runoff or wind-blown dust. Although ATSDR found no visibleevidence that stormwater runoff is affecting the residential areas, the surface soil contamination(less than one foot deep) was evaluated to determine if contaminants are at levels above screeningvalues. Stormwater runoff or wind is not likely to carry contaminated on-site soil that is deeperthan one foot to residential areas. Samples of on-site soil were collected during remedialinvestigations throughout the 1990s to determine the extent of soil contamination [12]. Arsenicwas detected in surface soil at a former storage yard (site S-7) at concentrations that exceededclosure guidelines [13]. Kelly AFB removed 1.2 acres of the arsenic contaminated surface soil in1997 and disposed of it off-site in accordance with TNRCC guidelines to attain closure status. Thestorage yard is no longer in use and arsenic concentrations are below background levels [14]. Inother areas of East Kelly, the four PAHs listed in Table 2 were detected in on-site surface soil atlevels above their health-based comparison values. Therefore, these PAHs were selected for further evaluation [15]:

Table 2.

East Kelly Soil Contaminants Detected above Comparison Values
Chemical Chemical Type Estimated Risk Risk-Based Comparison Value1 (mg/kg) Maximum Concentration (mg/kg)
1 1997 EPA Region III risk-based concentration for residential soil

The assumptions of the risk analysis for on-site surface soil are presented in Appendix C. Althoughthe maximum concentrations were detected above health-based comparison values, the levels ofthese contaminants have not been shown to cause adverse health effects in scientific literature. Theresults indicate that incidental ingestion of on-site soil is unlikely to cause adverse health effects.

Soil Gas

Soil gas consists of vapors within soil space that can potentially get in the air of an enclosed space.The soil gas can come from soil contaminants or groundwater migrating through these soil spaces.Residents living near East Kelly are concerned that vinyl chloride and other VOCs from thecontaminated shallow aquifer are migrating into their homes. Soil gas samples were taken outsideof homes that were identified where shallow groundwater contamination is highest, thus having thehighest potential for gas migration to indoor air [16]. Five soil gas monitoring wells were installedwest and south of East Kelly and three soil gas monitoring wells were installed east of East Kelly(Appendix A, figure 3). Soil gas was collected and analyzed in March 2000. Although vinylchloride was not detected in the soil gas, several other VOCs were detected. The levels of VOCsdetected directly in the soil gas are not expected to cause adverse health effects based onepidemiologic studies, even if they are inhaled directly [17] [18] [19] [20] [21] [22]. However, it isnot likely that residents near East Kelly will inhale soil gas directly. ATSDR estimated the indoorair concentration of each VOC detected above screening values in the soil gas using EPA'sJohnson and Ettinger model for subsurface vapor intrusion into buildings [23]. The indoor airconcentrations of VOCs are estimated to be about 60,000 times lower than the concentrationsdetected in soil gas directly (Appendix D). Based on the levels of VOCs in the soil gas and themodeling analysis, no adverse health effects are expected to occur from exposure to the VOCsdetected and estimated to be in the indoor air of homes located over contaminated shallowgroundwater. Appendix D details the results of the soil gas sampling results and the modeling.

  1. ATSDR Child Health Initiative

Children are at greater risk than adults from certain kinds of exposure to hazardous substancesemitted from waste sites and emergency events. They are more likely to be exposed for severalreasons; children play outside more often than adults, increasing the likelihood they will come intocontact with chemicals in the environment. Since they are shorter than adults, they breathe moredust, soil, and heavy vapors close to the ground. Children are also smaller, resulting in higher dosesof chemical exposure per body weight. The developing body systems of children can sustaindamage if toxic exposures occur during certain growth stages.

Many children live in neighborhoods surrounding East Kelly. Even though these children do nothave access to the site, ATSDR closely reviewed possible exposure situations to children whileevaluating this site. Based on the available sampling and modeling data, ATSDR did not identifyany chemical contaminants at levels of health concern to children living near East Kelly.

  1. Physical Hazards

East Kelly is surrounded entirely by a fence and guarded 24 hours a day. Therefore, public access iscontrolled at this site. ATSDR did not identify any physical hazards to the public during the evaluation of the site and the site visit.


  1. Exposure to the soil at East Kelly is not a public health threat based on the levels of contaminants detected.

  2. Several VOCs were detected in the soil gas in residential areas near East Kelly. However, based on soil gas concentrations and EPA's Johnson and Ettinger model, exposure to these contaminants at levels that cause adverse health effects is not likely.

ATSDR uses one of five conclusion categories to summarize our findings of the site. Thesecategories are: 1) Urgent Public Health Hazard, 2) Public Health Hazard, 3) Indeterminate HealthHazard, 4) No Apparent Public Health Hazard, and 5) No Public Health Hazard. A category isselected from site specific conditions such as the degree of public health hazard based on thepresence and duration of human exposure, contaminant concentration, the nature of toxic effectsassociated with site related contaminants, presence of physical hazards, and community healthconcerns. Based on these criteria, ATSDR determined that the environmental contaminationrelated to East Kelly presents a No Apparent Public Health Hazard based on levels ofcontaminants found in the on-site soil, the contaminants detected in the off-site soil gas, and the lack of human exposure to the contaminated shallow groundwater at levels of health concern.


Based upon the conclusions and information reviewed, ATSDR makes the followingrecommendation to TNRCC:

  1. Consider monitoring the shallow groundwater to track contaminant migration.


The actions described in this section are designed to ensure that this public health assessmentidentifies public health hazards and provides a plan of action to mitigate and prevent adverse healtheffects resulting from exposure to hazardous substances in the environment.

Actions Completed

  1. ATSDR has evaluated all existing environmental data pertaining to East Kelly as a basis for this public health assessment.

  2. ATSDR provided technical assistance to Kelly Air Force Base staff on the soil gas sampling plan.

  3. ATSDR presented several community forums for addressing health issues to the Restoration Advisory Board (RAB).

  4. ATSDR is developing a translation of this public health assessment in Spanish. The summary will be available to the public.

  5. ATSDR is developing a translation of this public health assessment in Spanish. The summary will be available to the public.

Action Planned:

  1. ATSDR will review additional environmental data as needed.


Preparer of Report:

Kimberly K. Chapman, MSEH
Environmental Health Scientist

Contributing Author:

Gregory M. Zarus, MS
Atmospheric Scientist

Technical Assistance:

Andrew Dent, MA
GIS Programmer/Analyst

Reviewers of Report:

Donald Joe, PE
Section Chief

John E. Abraham, PhD
Branch Chief

Susan Moore, MS
Section Chief

Review and Approval of this public health assessment for East Kelly.


Environmental Health Scientist, PRS, EICB, DHAC

Section Chief, PRS, EICB, DHAC

Branch Chief, EICB, DHAC


  1. Letter from Petitioner to ATSDR. 1996. Atlanta, GA.

  2. Kelly Air Force Base. November 1997. Focused Feasibility Study for Site SS051. Contract No. F41650-95-D-2005-5031. San Antonio, TX.

  3. United States Bureau of the Census. 1990. Census of Population and Housing: Summary Tape File 1B. U.S. Department of Commerce. Washington DC.

  4. Kelly Air Force Base. January 1999. Semiannual Compliance Plan Report. Project Documentation CD. San Antonio, TX.

  5. Kelly Air Force Base. March 1998. Kelly Facts. Kelly AFB, TX.

  6. ATSDR Record of Official Activity. March 14, 2000. Conversation between Kimberly Chapman of ATSDR and Nicholas Rodriquez of Bexar Met regarding date of municipal water line installation. Atlanta, GA.

  7. Science Applications International Corporation. October 1998. Kelly AFB/Bexar County, Texas Shallow Aquifer Assessment. Phase III. Technical Report. San Antonio, TX.

  8. US Air Force, Installation Restoration Program, Kelly Air Force Base. October 1999. Kelly AFB/Bexar County, Texas Shallow Aquifer Assessment. Phase IV. Master Well Listing. San Antonio, TX.

  9. Agency for Toxic Substances and Disease Registry. August 20, 1999. Petitioned Public Health Assessment for Kelly Air Force Base. CERCLIS No. TX2571724333. Atlanta, GA.

  10. Agustin, RAC. 1995. Analysis of the Potential for Plant Uptake of Trichloroethylene and an Assessment of the Relative Risk from Different Crop Types. Government Reports Announcements and Index. Issue 01.

  11. Agency for Toxic Substances and Disease Registry. May 3, 2000. Health Consultation for Lockwood Solvents in Billings, Montana. Atlanta, GA.

  12. Federal Facilities Information Management System. 2000. Soil Contamination: Kelly Air Force Base. Atlanta, GA.

  13. U.S. Air Force, Kelly Air Force Base. September 1997. IRP Site SS009 Closure Report. Final. San Antonio, TX.

  14. Kelly Air Force Base. November 29, 1999. Web address: Frequently Asked Questions:

  15. U.S. Environmental Protection Agency. October 22, 1997. Region III Risk-Based Concentration Table. Philadelphia, PA.

  16. CH2MHILL. March 2000. Informal technical information report: Zone 4 OU-2 and Site S-4 soil Vapor monitoring. Prepared for Kelly Air Force Base. No. 155728. San Antonio, TX.

  17. ATSDR. 1995. Toxicological Profile for Tetrachloroethylene. Atlanta, GA.

  18. ATSDR. 1995. Toxicological Profile for Trichloroethylene. Atlanta, GA.

  19. ATSDR. 1994. Toxicological Profile for Hexachlorobutadiene. Atlanta, GA.

  20. ATSDR. 1994. Toxicological Profile for 1,2-Dichloroethene. Atlanta, GA.

  21. ATSDR. 1998. Toxicological Profile for Methylene Chloride. Atlanta, GA.

  22. ATSDR. 1995. Toxicological Profile for Benzene. Atlanta, GA.

  23. U.S. Environmental Protection Agency. 1997. The Johnson and Ettinger Model for Subsurface Vapor Intrusion into Buildings. Washington, DC.

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