2
Exposure to Contaminants in Water Supplies at Camp Lejeune

This chapter describes the scenarios of exposure to contaminants in the water supplies at Marine Corps Base Camp Lejeune and identifies gaps in understanding of the exposures of people who lived or worked on the base while the water supplies were contaminated. First, exposure assessment for epidemiologic studies is discussed to set forth concepts that will be used in other chapters that review epidemiologic evidence (see Chapters 5 and 6). Then, an overview of the water-supply contamination scenarios at Camp Lejeune and important considerations for characterizing them are presented, including hydrogeologic features of the site, the base’s water-treatment plants and distribution systems, contaminated areas, and water-quality measurements. Finally, information on the Tarawa Terrace and Hadnot Point water systems is evaluated.

EXPOSURE ASSESSMENT FOR EPIDEMIOLOGIC STUDIES

In public health, the term exposure refers to contact with an agent (such as environmental contaminant) that occurs at the boundary between a person and the environment. Exposure assessment can be defined as the qualitative or quantitative determination or estimation of the magnitude, frequency, duration, and rate of exposure of a person or a population to a chemical (ILSI 2000). Often, the focus is on identifying one or more exposure pathways and, for each exposure pathway, the source, the environmental medium through which the contaminant is transported and possibly transformed, the receptor (individual or population), how contact occurs, and the route of exposure. The goal is to determine how much of a contaminant is absorbed and at what rate (the dose) so that an assessment can be made as to whether the absorbed contaminant produced or might produce an adverse biologic effect (Lioy 1990). The possible routes of exposure are inhalation, if the contaminant is present in the air; ingestion, through food, drinking, or hand-to-mouth behavior; and dermal absorption, if the contaminant can be absorbed through the skin. In the field of exposure science, research has been focused on developing methods for quantifying the uncertainty and error in the exposure assessments and on correcting the assessments for such error or uncertainty when possible. New methods are being developed to account for cumulative exposure to multiple chemicals (ILSI 2000), as are probabilistic models for cumulative and aggregate exposure assessment (for example, Nieuwenhuijsen et al. 2006) and the application of exposure modeling based on geographic information systems (Nuckols et al. 2004; Mindell and Barrowcliffe 2005; Beale et al. 2008).

A well-designed epidemiologic study should have the capability to evaluate exposure in relation to an appropriate latent period of a disease and to evaluate critical windows of exposure. In most epidemiologic studies, exposure cannot be measured directly or completely, and surrogate information is used to classify study subjects into exposure groups. Good surrogates for exposure elucidate the variation



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 28
2 Exposure to Contaminants in Water Supplies at Camp Lejeune This chapter describes the scenarios of exposure to contaminants in the water supplies at Marine Corps Base Camp Lejeune and identifies gaps in understanding of the exposures of people who lived or worked on the base while the water supplies were contaminated. First, exposure assessment for epidemi- ologic studies is discussed to set forth concepts that will be used in other chapters that review epidemi- ologic evidence (see Chapters 5 and 6). Then, an overview of the water-supply contamination scenarios at Camp Lejeune and important considerations for characterizing them are presented, including hydro- geologic features of the site, the base’s water-treatment plants and distribution systems, contaminated ar- eas, and water-quality measurements. Finally, information on the Tarawa Terrace and Hadnot Point water systems is evaluated. EXPOSURE ASSESSMENT FOR EPIDEMIOLOGIC STUDIES In public health, the term exposure refers to contact with an agent (such as environmental con- taminant) that occurs at the boundary between a person and the environment. Exposure assessment can be defined as the qualitative or quantitative determination or estimation of the magnitude, frequency, duration, and rate of exposure of a person or a population to a chemical (ILSI 2000). Often, the focus is on identifying one or more exposure pathways and, for each exposure pathway, the source, the environmental medium through which the contaminant is transported and possibly transformed, the receptor (individual or population), how contact occurs, and the route of exposure. The goal is to deter- mine how much of a contaminant is absorbed and at what rate (the dose) so that an assessment can be made as to whether the absorbed contaminant produced or might produce an adverse biologic effect (Lioy 1990). The possible routes of exposure are inhalation, if the contaminant is present in the air; ingestion, through food, drinking, or hand-to-mouth behavior; and dermal absorption, if the contaminant can be absorbed through the skin. In the field of exposure science, research has been focused on developing methods for quantifying the uncertainty and error in the exposure assessments and on correcting the assessments for such error or uncertainty when possible. New methods are being developed to account for cumulative exposure to multiple chemicals (ILSI 2000), as are probabilistic models for cumulative and aggregate exposure assessment (for example, Nieuwenhuijsen et al. 2006) and the application of exposure modeling based on geographic information systems (Nuckols et al. 2004; Mindell and Barrowcliffe 2005; Beale et al. 2008). A well-designed epidemiologic study should have the capability to evaluate exposure in relation to an appropriate latent period of a disease and to evaluate critical windows of exposure. In most epidemiologic studies, exposure cannot be measured directly or completely, and surrogate information is used to classify study subjects into exposure groups. Good surrogates for exposure elucidate the variation 28

OCR for page 28
Exposure to Contaminants in Water Supplies at Camp Lejeune 29 in exposure in the study population while minimizing exposure misclassification (error). Misclassification of exposure is of particular concern in environmental-epidemiology studies because the health effects of environmental exposures tend to be small, and it is usually difficult to accurately estimate exposure to environmental contaminants, which can occur by multiple pathways and in multiple locations. Further- more, environmental exposures are often at low concentrations, which make biases due to exposure mis- classification more likely to affect epidemiologic results. If misclassification of exposure is not differen- tial by health outcome, it commonly biases risk estimates toward the null (that is, toward finding no association) and can cause associations to be missed (Copeland et al. 1977; Flegal et al. 1986). To evalu- ate the degree of misclassification in an epidemiologic study, it is important to consider the ability of an exposure metric to correctly classify the magnitude of exposure in the study population and to differenti- ate between those who are exposed at magnitudes that could result in adverse health effects (sensitivity) and those who are exposed at lower magnitudes (specificity). It is important to maximize specificity when the prevalence of exposure in the study population is low and to maximize sensitivity when the preva- lence of exposure is high (Nuckols et al. 2004). Exposure assessment for epidemiologic studies of the effects of water-supply contamination in- cludes two components. The first is estimation of the magnitude, duration, and variability of contaminant concentrations in water supplied to consumers. An important consideration is hydrogeologic plausibility: an association between a contaminant source and exposure of an individual or population cannot exist unless there is a plausible hydrogeologic route of transport for the contaminant between the source and the receptor (Nuckols et al. 2004). The second component is information on individual water-use patterns and other water-related behaviors that affect the degree to which exposures occur, including drinking- water consumption (ingestion) and dermal contact and inhalation related to the duration and frequency of showering, bathing, and other water-use activities. Water use is an important determinant of variability of exposure to water-supply contaminants, particularly if it varies widely in the study population. Ideally, exposure-assessment strategies include both components, but in practice it may be difficult to obtain ei- ther adequately. A number of approaches have been used to assign exposures in studies of health effects of water- supply contamination. They have ranged from measures of exposure defined by geographic region or job classification (group-level or ecologic exposure) to more sophisticated measures that yield individual ex- posure estimates. Selecting an optimal approach for a given study is dictated in part by the epidemiologic- study design, the size and geographic extent of the affected population, and the quantity and quality of available exposure-related data. The approaches that have been used in epidemiologic studies of water- supply contamination are more fully described in Chapter 6. The following sections provide information on the water-supply contamination and exposure scenarios at Camp Lejeune. WATER-SUPPLY CONTAMINATION AT CAMP LEJEUNE In the early 1940s, the U.S. Marine Corps constructed a water-distribution piping system at Camp Lejeune. The source of water in the system was, and continues to be, groundwater wells. The water- treatment processes, distribution systems, and contributing wells have been modified to accommodate the additional demand due to population growth and to improve water quantity and quality. Four water sys- tems—Hadnot Point, Tarawa Terrace, Marine Corp Air Station, and Holcomb Boulevard—have supplied water to most of the residences and workplaces (see Figure 2-1). Other water-distribution systems on the base are Onslow Beach, Courthouse Bay, Rifle Range, and Camp Johnson. In late 1984 and early 1985, Marine Corps authorities removed a number of supply wells from service in the Tarawa Terrace and Hadnot Point systems after concluding that they were contaminated with solvents (GAO 2007). The sources of contamination of the two systems were different. Investigation into the source of perchloroethylene (PCE) contamination of the Tarawa Terrace water system concluded

OCR for page 28
Contaminated Water Supplies at Camp Lejeune—Assessing Potential Health Effects 30 FIGURE 2-1 Water-distribution systems serving U.S. Marine Corps Base, Camp Lejeune, North Carolina. Source: Maslia 2005. that it was due to waste-disposal practices at ABC One-Hour Cleaners, an off-base dry-cleaning facility (Shiver 1985). The dry-cleaning site was classified as a federal hazardous-waste site during March 1989 under the Comprehensive Environmental Response, Compensation, and Liability Act, commonly known as the Superfund Act, and remedial investigation began in 1990 (Faye and Green 2007). The Agency for Toxic Substances and Disease Registry (ATSDR) completed an extensive water-modeling study to pre- dict the extent of contamination (spatially and temporally) in the period January 1951–January 1994 (Faye 2008; see discussion of the modeling later in this chapter). Quantitative estimates of contaminant concentrations in the water supply from that modeling effort will be used in current and planned ATSDR epidemiologic studies of the Camp Lejeune population. A report from the U.S. Government Accountability Office (GAO 2007) states that the sources of contamination at Hadnot Point are uncertain but are likely to include many on-base sites, including land- fills and base operations where solvents and other compounds were disposed of or used. ATSDR plans to do a historical reconstruction for the Hadnot Point water-distribution system to estimate the extent of groundwater contamination of wells and the extent to which water supplies of housing and public build- ings served by this system were contaminated (M. Maslia, ATSDR, personal commun., March 12, 2008). The committee is not aware of any extensive studies concerning potential contamination of wells serving other water-supply systems on the base. Those wells directly serve the Holcomb Boulevard, Ma- rine Corps Air Station, Courthouse Bay, Camp Johnson, Camp Geiger, and Rifle Range water-supply sys- tems and several smaller systems. Some water-supply systems are connected (for example, Holcomb Boulevard and Hadnot Point), and Bove and Ruckart (2008) documents some reports of intermittent de- livery of water from the Hadnot Point system to the Holcomb Boulevard system.

OCR for page 28
Exposure to Contaminants in Water Supplies at Camp Lejeune 31 Hydrogeologic Features of Exposure at Camp Lejeune On the basis of geophysical data and lithologic logs, several productive aquifers were found to exist beneath Camp Lejeune. The geologic cross-sectional details on the site, as reported in Harden et al. (2004), are summarized in Figure 2-2. The aquifers include the Castle Hayne aquifer and two other deep aquifers beneath the Beaufort confining unit, the Beaufort and Peedee aquifers. All the water-supply wells were installed within the Castle Hayne aquifer, so site characterization efforts focused on understanding the hydrostratigraphy of the upper three hydrogeologic units: the surficial aquifer, the Castle Hayne con- fining unit, and the Castle Hayne aquifer. Each unit is known to have multiple subunits that consist of seams of clay, silt, and sandy beds (as indicated in Figure 2-2). The sections below summarize the avail- able hydrogeologic data for the three units. Surficial Aquifer The thickness of the surficial aquifer at Camp Lejeune ranges from 0 to 73 ft and averages about 25 ft (Cardinell et al. 1993). The largest observed thickness occurs in the southeastern part of Camp Le- jeune. The aquifer consists of interfingered beds of sand, clay, sandy clay, and silt of both Quaternary and Tertiary age. The clay and silt beds that occur in the surficial aquifer are thin and discontinuous. The aqui- fer is often classified into several subunits; and the extent and depth of the subunits can vary among loca- tions. For example, in the vicinity of Tarawa Terrace, three minor units have been identified in the surfi- cial aquifer (the Brewster Boulevard unit, the Tarawa Terrace unit, and the Upper Castle Hayne River bend unit). Review of available cross-sectional hydrogeologic data does not indicate any distinct demar- cation between the subunits; hence, they were conceptualized as a single surficial unit in groundwater- flow models (Faye and Valenzuela 2007). According to Winner and Coble (1989), the surficial aquifer is composed of more than 90% sand in the eastern part of the base and about 70-90% sand in the western part. The aquifer is directly recharged by infiltration from rainfall that ranged from 28 to 70 in/year during 1952-1994. Tant et al. (1974) found that the soils in Camp Lejeune have good infiltration capacity. Effec- tive groundwater recharge is estimated to range from 6.6 to 19.3 in/year. The estimated average hydraulic conductivity of the surficial aquifer in the Camp Lejeune area is about 50 ft/day (Winner and Coble 1989). Conceptually, groundwater in the shallow surficial aquifer moves from areas of high hydraulic head in interstream divides toward areas of low hydraulic head at surface-water discharge areas (Harden et al. 2004). Castle Hayne Confining Unit The Castle Hayne confining unit lies beneath the surficial aquifer, and this clayey unit is concep- tualized as the top confining layer of the Castle Hayne aquifer. However, the lithostratigraphic top of Cas- tle Hayne aquifer is not continuous, and the thickness of the confining layer ranges from 0 to 26 ft, aver- aging about 9 ft where present. Harned et al. (1989) concluded that no continuous confining unit or clay bed appears to separate the surficial and Castle Hayne aquifers except in the easternmost side of the Had- not Point area. Furthermore, the thickness and distribution of the confining clay layers observed in vari- ous cross sections summarized by Harned et al. (1989) and Cardinell et al. (1993) are similar. The thin (5- 10 ft) and discontinuous clay layers observed in several cross sections indicate that the degree of hydro- logic connection between the aquifers could be substantial (Harned et al. 1989). The vertical hydraulic conductivity of the confining material, where present, is estimated to range from 0.0014 to 0.41 ft/day (Cardinell et al. 1993).

OCR for page 28
32 FIGURE 2-2 Geologic cross section of Camp Lejeune. Source: Harden et al. 2004.

OCR for page 28
Exposure to Contaminants in Water Supplies at Camp Lejeune 33 Castle Hayne Aquifer The thickness of the Castle Hayne aquifer can range from about 200 to 400 ft. The aquifer is thinnest in the area of Camp Geiger in the northwest corner of the base and thickest in the eastern bound- ary. The bottom of the Castle Hayne aquifer is bounded by a regionally continuous clay unit, which is designated the Beaufort confining unit. All the groundwater-extraction wells in the base are in the Castle Hayne aquifer. The aquifer consists primarily of beds of sand, shell, and limestone (Winner and Coble 1989). The highly conductive material decreases from west to east across Camp Lejeune. The estimated hydraulic conductivity of the aquifer ranges from 14 to 91 ft/day (Cardinell et al. 1993). A portion of wa- ter from the surficial aquifer is able to infiltrate (move through or around) the upper confining unit, and this serves as the primary mechanism for recharging the Castle Hayne aquifer. Harned et al. (1989) also observed that in interstream areas the water level in the surficial aquifers can be 2-6 ft higher than the Castle Hayne aquifer and that the high vertical gradients can induce considerable vertical recharge. There is also some evidence of a potential for recharge of the Castle Hayne aquifer through the lower confining unit from the Beaufort aquifer (Cardinell et al. 1993). Finally, several paleostream channels have been identified within the Castle Hayne aquifer; these highly permeable, sandy channel beds can have consid- erable influence in local groundwater recharge, transport, and discharge patterns. Characteristics of Source Zones Predicting the dynamics of contaminant transport from contaminant source zones requires the use of groundwater models that simulate a complex set of fate and transport processes. Results from these models should be interpreted in light of a conceptual framework that integrates the chemical and geologic complexities in sources and receptors to establish a relationship between the contaminant source and the groundwater wells. An example of such a source-receptor conceptual model for a waste site contaminated with volatile organic compounds (VOCs) like PCE or TCE is illustrated in Figure 2-3. At a typical waste site, spent VOCs are present in the unsaturated zone (a partially saturated soil layer above the water table) in the form of dense nonaqueous-phase liquids (DNAPLs). Pure-phase VOCs are DNAPLs that do not mix with water and have an “oily” texture. They can be trapped in soil pore spaces, and their dissolution (dissolving process) is limited by a complex set of mass-transfer processes (Miller et al. 1991; Jackson 1998; Clement et al. 2004b). Furthermore, considerable spatial variability in DNAPL mass distribution in a source region is almost inevitable; consequently, mass detection at DNAPL-contaminated field sites is extremely difficult and uncertain (Abriola 2005). Laboratory-scale tank studies have indicated that under typical groundwater-flow conditions the DNAPL dissolving process will be limited by various mass-transfer processes, so concentrations of only about 10-20% of the maximum solubility level can be obtained (Clement et al. 2004a). Furthermore, waste DNAPLs, similar to the ones disposed of at Camp Lejeune, may mix with other chemicals that limit the mass-transfer kinetics further and lead to considerable reduction in solubility (Clement et al. 2002). Therefore, the presence of even a small volume of DNAPL can contaminate a large volume of groundwa- ter for several decades as DNAPL continues to dissolve. Figure 2-3 illustrates various possible pathways for groundwater contamination from a DNAPL source. If the quantity of the waste product (DNAPL) is high enough, the waste will migrate downward and penetrate the water table. The vertical migration will eventually cease, and the DNAPL will be trapped in the pore spaces or will pool over low permeable clay layers. The DNAPL phase will slowly dissolve into the water phase, and the dissolved plume will be transported toward the extraction wells. The migration patterns of DNAPL contaminants will also be highly influenced by local hydrogeologic conditions. The presence of low-permeability units (such as the Castle Hayne confining unit or any clay units) would limit vertical migration of both DNAPL and dissolved contaminants. At Camp Lejeune, all

OCR for page 28
Contaminated Water Supplies at Camp Lejeune—Assessing Potential Health Effects 34 WELL UNSATURATED ZONE UNSATURAED ZONE SATURATED SATURATED ZONE WELL SCREEN FIGURE 2-3 Conceptual model of DNAPL transport. The well is shown at an exaggerated scale. Source: Modified from Jackson 1998. Reprinted with permission; copyright 1998, Hydrogeology Journal. the groundwater-supply wells are beneath the surficial aquifer. Therefore, the ability of the contaminants to reach the receptor (well screen) at the site depends on local groundwater gradients, on the thickness (or existence) and geometry of the low-permeability clay or silt zones between the source and the well, and on the geometry of the hydrostratigraphic units. The presence of a thick clay unit between the source and the receptor retards transport; however, strong pumping could induce vertical gradients and enhance con- taminant transport. Water-Treatment Plants and Distribution System A chronology of the water-supply systems providing water to the residential areas at Camp Le- jeune from 1941 to 2000 is presented in Table 2-1. At various times, four systems have been the primary sources of water for residences other than barracks at Camp Lejeune since the first system was put into service: Hadnot Point, Tarawa Terrace, Marine Corps Air Station, and Holcomb Boulevard. Several smaller systems have supplied or still supply other areas of the base that have relatively low populations. For each system, a set of supply wells pumped water to a centralized water-treatment plant, where the water was mixed before distribution to housing areas, public buildings (such as schools), businesses, and workplaces. Figure 2-4 provides an illustration of a conceptual model of a water-supply system at Camp Le- jeune. Water-supply wells collected groundwater and pumped it to the water-treatment plant when the wells were turned on. Not all the wells operated at the same time. The wells were “cycled,” meaning that only a few wells pumped water to the treatment plant at any given time. Water from several wells was mixed at the treatment plant and processed before being distributed in the pipes that supplied water to the base. Limited historical information is available on the pumping schedules of the wells or the water- treatment techniques that were used.

OCR for page 28
Exposure to Contaminants in Water Supplies at Camp Lejeune 35 In general, the water-treatment processes used by the Marine Corps generally included coagula- tion, sedimentation, filtration (with sand or anthracite), and lime softening (Marine Corps, personal com- mun., May 22, 2008). The American Water Works Association (AWWA) reported that efficiency of re- moval of VOCs would be poor (0-20%) without lime softening and poor to fair (0-60%) with lime softening, of synthetic organic chemicals poor to good (0-80%), and of metals good to excellent (80- 100%) except for chromium+6 (less than 20%) (AWWA 1995). Actual removal efficiencies are site- specific and depend on how each water-treatment plant is operated. TABLE 2-1 Water Supply of Housing Areas, Camp Lejeune, North Carolina (1941-2000) Housing Area Water-Treatment Plant Dates of Service Family housing areas Courthouse Bay Courthouse Bay 1942-2000 Berkeley Manor Hadnot Point 1961-1971 Holcomb Boulevard 1972-2000 Hospital Point Hadnot Point 1947-2000 Knox Trailer Park Tarawa Terrace 1952-1986 Holcomb Boulevard 1987-2000 Knox Trailer Park Expanded Holcomb Boulevard 1989-2000 Marine Corps Air Station Marine Corps Air Station 1958-2000 Midway Park Hadnot Point 1943-1971 Holcomb Boulevard 1972-2000 Paradise Point Cape Cod Hadnot Point 1948-1971 Holcomb Boulevard 1972-2000 Paradise Point Capehart Hadnot Point 1962-1971 Holcomb Boulevard 1972-2000 Paradise Point Cracker Box Hadnot Point 1947-1971 Holcomb Boulevard 1972-2000 Paradise Point general officer housing Hadnot Point 1943-1971 Holcomb Boulevard 1972-2000 Paradise Point two-story housing Hadnot Point 1943-1971 Holcomb Boulevard 1972-2000 Rifle Range housing Rifle Range 1942-1993 Onslow County 1994-2000 Tarawa Terrace I and II Tarawa Terrace 1952-1986 Holcomb Boulevard 1987-2000 Watkins Village Holcomb Boulevard 1978-2000 Barracks subcamps (not individual barracks) Camp Geiger Camp Geiger 1941-1976 Marine Corps Air Station 1977-2000 Camp Johnson Camp Johnson 1941-1986 Holcomb Boulevard 1987-2000 Courthouse Bay Courthouse Bay 1941-2000 French Creek Hadnot Point 1943-2000 Hadnot Point Hadnot Point 1943-2000 Rifle Range Rifle Range 1941-1993 Onslow County 1994-2000 Source: Marine Corps, personal commun., March 13, 2008.

OCR for page 28
Contaminated Water Supplies at Camp Lejeune—Assessing Potential Health Effects 36 FIGURE 2-4 Conceptual model of a Camp Lejeune water system. (1) The drinking water at Camp Lejeune is ob- tained from groundwater pumped from a freshwater aquifer located approximately 180 ft below the ground. (2) Groundwater is pumped through wells located near the water-treatment plant. (3) In the water-treatment plant, the untreated water is mixed and treated through several processes: removal of minerals to soften the water, filtration through layers of sand and carbon to remove particles, chlorination to protect against microbial contamination, and fluoride addition to help prevent tooth decay. (4) After the water is treated, it is stored in ground and elevated stor- age reservoirs. (5) When needed, treated water is pumped from the reservoirs and tanks to facilities, such as offices, schools, and houses on the base. Source: GAO 2007. Review of Contaminated Areas The committee evaluated data on hazardous-waste site locations and characteristics in the vicinity of the water-supply well and residential service locations for the water systems listed in Table 2-1 (Baker Environmental, Inc 1999, CH2M Hill and Baker Environmental, Inc 2005). Table 2-2 summarizes the contaminants found in soil or groundwater at waste sites near supply wells. Details of the contamination near supply wells serving Tarawa Terrance and Hadnot Point are presented later in this chapter. Waste sites in the vicinity of other water-supply areas are described briefly in Appendix C (Table C-1). COMMITTEE’S WATER-SUPPLY EVALUATION APPROACH The committee focused its attention on the Tarawa Terrace and Hadnot Point water-supply sys- tems. The systems were evaluated differently because much more work had been done to characterize the contamination of the Tarawa Terrace system than that of the Hadnot Point system. For Tarawa Terrace, the committee relied exclusively on reports by ATSDR (Faye 2007; Lawrence 2007; Faye and Green 2007; Faye and Valenzuela 2007; Maslia et al. 2007; Faye 2008; Jang and Aral 2008; Wang and Aral 2008). The reports included analyses of the water-quality data conducted in conjunction with ATSDR’s

OCR for page 28
Exposure to Contaminants in Water Supplies at Camp Lejeune 37 TABLE 2-2 Contaminants Found in Soil or Groundwater at Hazardous Waste Sites Near Water-Supply Wells Approximate Number Identified Contaminants Detected in Soils (S) or Water System Hazardous-Waste Sites Monitoring Wells (M, D) Tarawa Terrace 2 Chlorinated solvents (S ,M, D) BTEX (S, M) Hadnot Point 13 Pesticides (S, M) Polychlorinated biphenyls (S) Metals (S, M) Chlorinated solvents (S, M, D) Fuel compounds (M) Benzene (M) Toluene (M) Ethylbenzene (M) Xylenes (M) BTEX (M) Petroleum products (S, M) Volatile compounds (S) Semivolatile compounds (S) Holcomb Boulevard 5 Pesticides (S, M) Volatile and semivolatile compounds (S, M) Metals (M) Marine Corps Air 6 Volatile and semivolatile compounds at two Station locations (S, M) Pesticides at one location (S, M) Rifle Range 2 VOCs (M) Camp Geiger 13 Chromium (M) Lead (M) VOCs (M) Camp Johnson 2 None Abbreviations: BTEX = benzene, toluene, ethylene, and xylene; D = deeper wells in Castle Hayne aquifer, source of water-supply wells; M = shallow wells, surficial aquifer, or soil vadose zone. Sources: Baker Environmental, Inc 1999; CH2M Hill and Baker Environmental, Inc 2005. water-quality modeling. For Hadnot Point, the committee conducted its own review of information that was in the public record. The committee used multiple sources, including the 2007 GAO report, remedial investigation reports (Baker Environmental, Inc 1993, 1994, 1995), data summarized in the “Camp Le- jeune water”(CLW) documents (CD accompanying Maslia et al. 2007), and planning documents from ATSDR (Maslia 2008). The goal was to get an understanding of the contamination of water supplies serv- ing Hadnot Point residents, including which VOCs were of potential concern and the degree to which contaminant concentrations in the water supply varied. In consulting the CLW documents, the committee focused on contaminant measurements taken while the contaminated wells were operating, including measurements of the water-supply wells and from the water-treatment plant and distribution system. As noted earlier, water from the supply wells was mixed at the water-treatment plant before distribution. Be- cause all water samples from the distribution system were taken after water from multiple supply wells was mixed, they were categorized as “mixed” water samples. Sampling of mixed water occurred before and after water was treated or “finished.” Samples taken from mixed water give a better indication of the concentrations of contaminants delivered to the tap than samples taken from supply wells. However, wa- ter-quality data on the individual supply wells shed light on the wells that were contaminated and permit preliminary documentation of the extent of contamination. In determining its approach to evaluating the water-quality data on Hadnot Point, the committee wrestled with reporting data that have not been collected by a process that involved standard quality- assurance procedures. The process that was used for abstraction of the water-quality data (see Appendix

OCR for page 28
Contaminated Water Supplies at Camp Lejeune—Assessing Potential Health Effects 38 C) did not consider multiple aspects of the data, including the sampling strategy, methods for sample col- lection and analysis, chain of custody of samples, recording and interpretation of detection or quantitation limits, and duplication of sampling results in source documents. Thus, the data cited are only for illustra- tive purposes, and references to the primary documents are provided to facilitate additional work. TARAWA TERRACE WATER SUPPLY Discovery and Investigation of the Contamination at Tarawa Terrace The Tarawa Terrace water-supply system began operations in 1952. Seven wells initially supplied water to the system, and more wells were added over the years. A total of 16 wells served the system at some time between 1952 and 1987. The wells operated on a cycled schedule. Wells were taken offline or were closed for various reasons between 1962 and 1987 (Maslia et al. 2007). During August 1982, a routine analysis with gas chromatography-mass spectrometry (to screen the water samples collected from the Tarawa Terrace water-treatment plant for chlorination byproducts) indicated high concentrations of halogenated hydrocarbons, a class of VOCs (Faye and Green 2007). Fur- ther analysis confirmed the presence of PCE in finished water at 76-104 µg/L (Faye and Green 2007). Sporadic sampling in 1982-1985 also indicated detectable concentrations of TCE, which is a degradation byproduct of PCE. In January 1985, the North Carolina Department of Natural Resources and Community Develop- ment (NCDNRCD) began routine sampling of water from supply wells TT-23, TT-25, and TT-26 and finished water from the water-treatment plant (Faye 2008). The data indicated varied PCE and TCE con- tamination. For example, PCE ranged from nondetectable to 132 µg/L and from 3.8 to 1,580 µg/L in wells TT-23 and TT-26, respectively. Wells TT-23 and TT-26 were temporarily removed from service in February 1985. Later, well TT-26 was closed permanently, and well TT-23 was used intermittently for several days during March and April 1985 and finally shut down in April 1985 (GAO 2007). From Janu- ary to September 1985, samples were taken from wells TT-30, TT-31, TT-52, TT-54, and TT-67, and PCE and its degradation products were not detected. In April 1985, NCDNRCD conducted extensive field investigation to map the PCE plume and identify the contaminant source. On the basis of that investigation, the northwest edge of the plume was determined to be close to ABC One-Hour Cleaners. A shallow monitoring well installed close to the cleaners detected an extremely high PCE concentration of 12,000 µg/L (Faye and Green 2007). Such a high concentration is an indication of a source region that contains pure-phase PCE (the highest possible concentration of PCE in water is about 110,000 µg/L). Further investigations revealed that ABC One- Hour Cleaners had routinely used PCE in dry-cleaning operations since 1953. Shiver (1985) reported that PCE releases from various accidental spills entered the septic system through a floor drain. Furthermore, spent PCE was routinely put through a filtration-distillation process that produced dry still bottoms (sludge). Until about 1982, such waste products were used to fill potholes in a nearby alleyway. The exact date of the termination of those disposal practices is unknown; ATSDR estimates that they ceased in 1985 (Faye and Green 2007). Several on-base sources and episodes were documented. Faye and Green (2007) report that a “strong gasoline type odor” was noted at water-supply well TT-53 during October 1986 while personnel from the U.S. Geological Survey (USGS) conducted a routine well reconnaissance. The well was not in service at the time. The gasoline contamination was traced to various spills and leaks from 12 under- ground storage tanks (USTs) associated with various buildings in the Tarawa Terrace shopping center. For example, on September 21, 1985, a catastrophic failure discharged about 4,400 gal of unleaded gaso- line to the subsurface. A review of past releases indicated that small leaks of gasoline products probably occurred at the site beginning in the 1950s. As of May 4, 1987, more than 2 ft of floating gasoline was determined to be present above the water table in the vicinity of Building TT-2453.

OCR for page 28
TABLE 2-11 Hadnot Point Water-Supply Quality Measurements (October 1980-February 1985) 56 No. Samplesa Summarized Data on Samples with Quantified Values, µg/Lb Water % Samples Individual 25th 75th Source Contaminant Quantified Samples, µg/L ND/NQc Quantified Mean Min Percentile Median Percentile Max TCE 39 17 30 2,596 5 13 210 1,300 18,900 Supply wells PCE 48 8 14 153 2 5 17 392 400 Benzene 50 6 11 180 2 4 62 230 720 1,1,1-TCA 56 0 0 1,1-DCE 54 2 4 2; 187 95 trans-1,2-DCE 42 14 25 1,519 2 9 165 700 8,070 MC 50 6 11 78 7 10 26 130 270 Toluene 54 2 4 5; 12 9 VC 51 5 9 205 7 18 168 179 655 d 31 60 399 1 19 200 849 1,400 Mixed TCE 21 d water PCE 48 4 8 1; 4; 8; 15 7 Benzene 52 0 0 1,1,1-TCA 52 0 0 1,1-DCE 52 0 0 trans-1,2-DCE 31 21 40 169 2 9 150 321 407 MC 51 1 2 54 54 Toluene 52 0 0 VC 51 1 2 3 3 a Samples in this table listed separately in Appendix C, Tables C-3 and C-4. Samples treated as distinct if reported on separate laboratory reports; in some cases, multiple samples reported from same location on same date, but it is not known whether these were duplicate samples. b Sample concentrations presented as summary statistics if more than four samples were quantified. Quantified samples listed individually if four or fewer sam- ples quantified. c ND/NQ samples do not have reported concentrations for various possible reasons, including that they were not measured, were not detected, or were recorded merely as detected. See Table 2-12 for additional information about these samples. d Concentrations measured in seven of 11 samples collected before 1984 were assumed to be detected on basis of notes on laboratory reports and inferences from later laboratory reports. Abbreviations: DCE = dichloroethylene; MC = methylene chloride; ND = not detected; NQ = not quantified; TCA = trichloroethane; VC = vinyl chloride.

OCR for page 28
TABLE 2-12 Summary of Data on Water Samplesa from Hadnot Point Water System Recorded As Not Detected or Not Quantified in Table 2-11 Water Source ND/NQ Category Contaminant ND/NQ Reported as Detected <2.0 or <1 µg/L ND No data TCE 39 39 Supply wells PCE 48 48 Benzene 50 50 1,1,1-TCA 56 56 1,1-DCE 54 54 trans1-2,DCE 42 42 MC 50 50 Toluene 54 54 VC 51 51 b 7 6 7 1 Mixed water TCE 21 PCE 48b 7 2 12 27 Benzene 52 14 38 1,1,1-TCA 52 14 38 1,1-DCE 52 14 38 trans1-2,DCE 31 7 10 14 MC 51 13 38 Toluene 52 14 38 VC 51 13 38 a Data listed separately in Appendix C (Tables C-3 and C-4). Samples treated as distinct if reported on separate laboratory reports; in some cases, multiple sam- ples reported from same location on same date, but it is not known whether these were duplicate samples. b Concentrations measured in seven of 11 samples taken before 1984 assumed to be detected on basis of notes on laboratory reports and inferences from later laboratory reports. Abbreviations: DCE = dichloroethylene; MC = methylene chloride; ND = not detected; NQ = not quantified; TCA = trichloroethane; VC = vinyl chloride. 57

OCR for page 28
58 TABLE 2-13 Characteristics of the Hadnot Point Supply Wells With At Least One Contaminated Sample Taken Between October 1980 and February 1985 Wella Well Contaminants, µg/Ld Depth, Screened Intervals, No. Water Year Well Date Well Trans-1,2- ftc IR Siteb Number (Range, ft) c Samplesd Started Shut Downe TCE PCE DCE 1,1-DCE MC VC Benzene Toluene 601 9, 78 195 4 (45-195) 3 26 ND 9 ND 1941 Dec. 6, 1984 210 4 88 ND 230 5 99 10 602 9, 78 160 5 (70-160) 4 38 ND 74 ND ND ND ND 1941 Nov. 30, 1984 340 ND 230 ND ND 120 ND 540 2 380 ND ND 230 5 1,600 24 630 2 18 720 12 603 78 195 5 (70-195) 3 ND ND 1941 ND ND 5 7 608 78 161.5 4 (61.5-161.5) 3 9 ND ND 2 1942 Dec. 6, 1984 13 2 ND 4 110 5 14 4 634 9, 78 225 10 (63-225) 3 ND ND ND ND ND 1959 Dec. 14, 1984 ND ND 2 ND ND 1,300 10 700 130 7 637 6, 9, 78, 172 5 (90-172) 3 ND 1969 Dec. 14, 1984 82 ND 270 642 9, 78 210 5 (112-196) 3 ND 1971 ND 38 3,200 386 3,400 ND 168 1971 Feb. 4, 1985 651 9, 82 199 3 (125-194) 3f 17,600 397 7,580 ND 179 18,900 400 8,070 187 655 652 1 9 1972 Feb. 8, 1985 653 6, 82 270 1 6 1978 Feb. 8, 1985 a Wells installed before March 1, 1985. Many other wells were operating before March 1, 1985, but are not included in list because contaminants not detected. b See Figure 2-6. c Data abstracted from Baker Environmental, Inc (1993a,b). d Samples listed in Appendix C, Table C-4. All readings are shown for individual compounds with at least one detection. e Well-closing dates reported in GAO (2007). f Includes two samples collected on same date and listed as “duplicates” on secondary source document. Abbreviations: DCE = dichloroethylene; IR = installation restoration; MC, methylene chloride; ND = not detected; PCE = perchloroethylene; TCE = trichloroethylene; VC = vinyl chloride.

OCR for page 28
Exposure to Contaminants in Water Supplies at Camp Lejeune 59 TABLE 2-14 Concentrations of Contaminants in Mixed Water Samples Collected from Hadnot Point Water-Distribution System During Period of Documented Well Cyclinga Average Concentration, µg/Lb No. Water No. Wells trans-1,2- Samplesc Wellsd Date Pumping TCE PCE DCE MC 603, 608, 634, 637, 642, 652e Dec. 4, 1984 2 123 2 49 0 21 Dec. 10, 1984 1 2 0 2 0 10 637, 652 Dec. 13, 1984 1 0 0 0 54 18 652, 653 Dec. 14, 1984 1 0 0 0 0 18 652 Dec. 15, 1984 1 0 0 0 0 15 642, 652 Dec. 16, 1984 1 0 0 0 0 13 642, 652 Dec. 17, 1984 1 0 0 0 0 13 603, 642, 652 Dec. 18, 1984 1 0 0 0 0 13 603 Dec. 19, 1984 2 1 0 0 0 13 603 f f f 18 603, 642, 651, 653 Jan. 29, 1985 3 463 f f Jan. 31, 1985 14 618 225 19 603, 642, 651, 652, 653 a Dates estimated to be November 28, 1984, through February 4, 1985. b All nondetected values treated as having concentrations of 0. c The location from which the samples were taken are provided in Appendix C, Table C-3. d Wells with at least one detected analyte that were pumping on same day or up to 2 days before date specified. e Well 651 pumped 3 days before these samples were taken. f Contaminant not measured or reported for mixed water samples collected on this date. Abbreviations: DCE = dichloroethylene; MC = methylene chloride; PCE = perchloroethylene; TCE = trichloro- ethylene. period to ascertain the potential effect of well cycling on measured contaminant concentrations. To illus- trate the effect of well cycling on mixed-water contamination, the committee made the highly conserva- tive assumption that all “non-detect” samples had zero concentrations of the listed contaminants. The ta- ble indicates that 10-21 wells delivered raw water to the water-treatment plant on days when at least one mixed-water sample was analyzed. At least one well with demonstrated contamination pumped on the same day or previous 2 days from the dates when water samples were collected, but contamination in the mixed water was not detected on all dates on which a sample was collected. TCE, PCE, trans-1,2-DCE, and methylene chloride were detected in mixed-water samples taken during November 28, 1984-February 4, 1985. Benzene, 1,1-DCE, toluene, and vinyl chloride—all of which were reportedly detected in the Hadnot Point supply-well samples—either were not included in the laboratory analysis or were not detected in measurable concentrations in mixed-water samples during that period. The two dates with the highest average TCE concentrations (463 and 618 µg/L) were the dates when well 651 was supplying water to the system on the current and/or previous 2 days; this suggests that well 651 was an important source of contamination of the Hadnot Point water-supply system. In addition, the 14 mixed-water TCE measurements in samples from one of those days (January 31, 1985) had a range of 24-1,148 μg/L. Hadnot Point Area Monitoring Wells The committee focused its review on some of the earliest deep-groundwater monitoring data available from the remedial-investigation reports for waste sites 6, 9, 78, and 82 in the Hadnot Point area (Baker Environmental, Inc 1994). Monitoring wells were used to collect water samples from depths of about 148-153 ft below ground surface. Screens (elevations of water-intake portals in the well pipe) in

OCR for page 28
Contaminated Water Supplies at Camp Lejeune—Assessing Potential Health Effects 60 most of the wells that supplied water to the Hadnot Point water system were installed at depths of 60-190 ft below ground surface. Each supply well had three to five screens. Thus, the analytic results on water samples taken from deep monitoring wells should be representative of contamination of the Castle Hayne aquifer at a depth consistent with water withdrawal from the water supply, albeit at least 7 years after the discovery of contaminants in the Hadnot Point supply wells. The remedial investigation of site 78 was preceded by several investigations, including an initial assessment study (1983) that identified the groundwater contamination and a confirmation study (1984- 1988) that documented the presence of VOCs related to fuels and solvents in the groundwater. A later supplemental characterization step study (1990-1991) and pre-investigation study (1992) set the stage for the systematic sampling effort for the remedial investigation in 1992 (Baker Environmental, Inc 1994). Groundwater in the vicinity of sites 6 and 82 was also sampled as part of the confirmation study (1984-1988). The remedial investigation of sites 6 and 82 included three rounds of groundwater sampling, conducted in two phases: phase 1 in 1992 and phase 2 in 1993 (Baker Environmental, Inc 1993). The in- vestigation at each site, including groundwater sampling and analyses, continued after the publication of the remedial-investigation reports. The committee judged that the focus on the remedial-investigation re- ports for Hadnot Point sites was justified because they provided a reasonable snapshot of contamination closest to the period of interest. For the remedial investigation, groundwater samples were generally analyzed for two suites of common chemical contaminants known as the “target compound list” (TCL) and the “target analyte list” (TAL). The results of the detections are summarized below; a more complete discussion is presented in Appendix C (Table C-5). The monitoring-well data identify TCE, phenol, benzene, cis- and trans-1,2-DCE, and 1,1-DCE as the most prevalent contaminants in groundwater at the locations and screened depths of the wells. Other contaminants with multiple detections were arsenic, cadmium, 1,2-dichloroethane, and PCE. TCE, phenol, and cis- and trans-1,2-DCE had the highest prevalence of concentrations measured above their limits of detection. Concentrations reported in the remedial-investigation reports varied widely among the well sites. For example, the concentrations of TCE in 11 samples ranged from 1.3 to 58,000 µg/L. Similarly, detec- tions of trans-1,2-DCE ranged from 1 to 26,000 µg/L, of phenol from 2 to 22,000 µg/L, and of benzene from 6.7 to 35 µg/L. The most contaminated locations were near supply well 651, next to sites 6 and 82. At most locations, shallow groundwater (sampled at a depth of less than 25 ft) had the greatest number of contaminant detections, including such TCL chemicals as TCE (0.5-2,100 µg/L) and fuel con- stituents benzene (not detected to 9,200 µg/L), toluene (not detected to 18,000 µg/L), ethylbenzene (not detected to 3,000 µg/L), xylenes (not detected to 16,000 µg/L), and naphthalene (not detected to 260 µg/L) (Baker Environmental, Inc 1993, 1994). TAL metals that were commonly detected in shallow wa- ter, with some samples at exceedingly high concentrations relative to EPA’s current MCLs, were arsenic (405 µg/L), barium (1,200 µg/L), chromium (858 µg/L), lead (126 µg/L), and manganese (714 µg/L) (Baker Environmental, Inc 1993, 1994). Only five wells of intermediate depth (about 50-75 ft) were sam- pled as part of the remedial investigation, and detected chemicals were generally measured at concentra- tions below risk-based criteria. The results of groundwater sampling and analysis with monitoring wells provide additional in- formation regarding the presence of contaminants in the aquifer. In many ways, the data are secondary to the analytic results on samples taken from the supply wells or the tap, at least for the purposes of under- standing historical exposures. However, because the available information on such samples is sparse, it is important to consider all available data, including those from monitoring wells. Contaminants of Concern in the Hadnot Point Water Supply The paucity of water-quality measurements of the Hadnot Point water supply, both temporally and spatially, makes it difficult to characterize the contaminants of concern accurately. Multiple waste

OCR for page 28
Exposure to Contaminants in Water Supplies at Camp Lejeune 61 and operational sites have contributed to the groundwater contamination since the 1940s, so the nature of the contamination has probably varied. The few available measurements were taken during the 1980s and 1990s, decades after the contamination could have begun. The principal contaminants discovered in the wells that supplied Hadnot Point in the early 1980s were TCE and PCE. TCE, phenol, benzene, cis- and trans-1,2-DCE, and 1,1-DCE were the most prevalent contaminants in samples collected in 1992 and 1993 from deep monitoring wells. Other contaminants with multiple detections in monitoring wells were arsenic, cadmium, 1,2-dichloroethane, and PCE . The chemical 1,1,1-TCA, which was on the preliminary list of contaminants of concern compiled by the committee, is given only cursory attention in this report because it was not observed in any Hadnot Point water-quality samples collected before February 8, 1985. However, 1,1,2-trichloroethane was detected in one sample from a monitoring near well 651 at 5.8 µg/L (see Appendix C, Table C-5). Groundwater Fate and Transport Model for Hadnot Point ATSDR has proposed that the methods that were used for Tarawa Terrace be applied to recon- struct the historical contamination of water supplied by the Hadnot Point water-treatment plant (Maslia 2008). The proposed reconstruction will simulate the groundwater concentrations of TCE, PCE, and BTEX (benzene, toluene, ethylbenzene, and xylene). The preliminary data-screening efforts started in January 2008, and work is expected to be completed on October 2009. The study includes 10 technical tasks: analysis of data from16 sites; computation of mass of PCE, TCE, and BTEX at about six major sites; review of capacity histories of about 100 wells; statistical analysis of existing data; fate analysis; fate and transport model selection; grid design and data input; fate and transport analysis; water- distribution system analysis; and uncertainty analysis. ATSDR is also committed to providing updates on its progress by participating in external progress meetings and Community Assistance Panel meetings and by preparing and disseminating data analyses and model simulations. On the basis of work already carried out, ATSDR also indicated the following (Maslia 2008):  Discovery of new or updated site information after the second quarter of FY 2008 that substan- tially alters baseline information may add time to the current timeline estimate.  Because of the expanse of the area being modeled, computational time for fate and transport analyses may be longer than previously estimated. When model selection and grid design have been com- pleted, a more refined estimate of required computational time will be made. Earlier in this chapter, the committee identified several limitations in the Tarawa Terrace histori- cal reconstruction and groundwater modeling. Because the contamination at Hadnot Point is more com- plex, the limitations and difficulties related to such modeling will be greater. WATER USE PATTERNS AND BEHAVIORS Place of residence is a key determinant of exposure to contaminants in water at Camp Lejeune, but individual behavior—including water consumption, showering or bathing patterns, and other water- related behaviors (such as dishwashing)—also would influence the degree of exposure. The committee is not aware of any historical information that documents individual water-use patterns and behaviors of residents of base housing. Some information on typical water use and other factors that affect individual exposure is available (EPA 1997, 2008). Some specific information on the Camp Lejeune population is being sought as part of ATSDR’s case-control study focused on birth defects and childhood cancer out- comes (see Chapter 8). However, as in all retrospective epidemiologic studies of water-supply contamina- tion, the validity of such information is open to question given that it requires retrospective recall of wa- ter-consumption habits and water-related behaviors that occurred decades earlier, increasing the like-

OCR for page 28
Contaminated Water Supplies at Camp Lejeune—Assessing Potential Health Effects 62 lihood that error due to recall bias could be substantial. The contaminated water systems also supplied nonresidential areas of the base, including schools, workplaces, recreational areas, and a hospital. Water- use patterns and behaviors in those setting are expected to differ substantially from practices in resi- dences. In addition, people could have been exposed to contaminated water at multiple locations, for in- stance, in both residential and nonresidential settings. EXPOSURE PATHWAYS Although most attention has focused on the ingestion of contaminated water, additional exposure pathways were possible, including the inhalation of chemicals that have volatilized from standing water in toilets or from faucet or shower water and dermal exposure from showering and washing. Although there are no contemporaneous data on the Camp Lejeune population, exposure via inhalation and dermal ab- sorption of VOCs from water used for household purposes has been shown experimentally to account for as much exposure as that from drinking the water (see Chapter 3). The intrusion of vapor from shallow contaminated groundwater into homes and offices is yet another possible inhalation-exposure pathway. ATSDR’s simulation efforts indicate a potential for vapors from plumes at Tarawa Terrace to have en- tered buildings, including an elementary school and family housing (Maslia et al. 2007). EPA recently examined the possibility of vapor intrusion at the Tarawa Terrace Elementary School and several housing units and did not find any current problems (EPA 2007a,b). Any estimates of past exposure to contami- nated groundwater should consider all exposure pathways. AFFECTED STUDY POPULATION Residential history in housing areas served by the contaminated water supplies during the period of contamination is an important determinant of exposure. There are two major categories of housing at Camp Lejeune: family housing for personnel on assignment to Camp Lejeune and barracks for enlisted personnel rotating through the base for training. The committee was provided with an estimated number of residential houses on Camp Lejeune by water-supply system in any given year from 1941 to 2000 by the Marine Corps (Appendix C, Table C-6). The first year with substantial residential water service was 1943, in which an estimated 919 units were served by the Hadnot Point water system, the first to serve a residential development on the base other than a barracks. Large increases in the total number of family- housing units on the base occurred in 1952, with the construction of Tarawa Terrace housing (3,065 units); in 1958, with the construction of Marine Corp Air Station housing (3,500); in 1961, with the con- struction of Berkeley Manor and Paradise Point Capehart housing (4,177); and in 1978, with the construc- tion of Watkins Village housing (4,550). Substantial shifts in the water-supply source for residential hous- ing occurred in 1972 when about 1,886 housing units were transferred from the Hadnot Point water system to the Holcomb Boulevard system and in 1987 when about 1,955 housing units were transferred from the Tarawa Terrace system to the Holcomb Boulevard system. Translating the number of housing units into the size of the population that may have been exposed would require knowledge of the number of residents per household or at least the number of residents by housing area in each year. To translate that into potential years of residential exposure for a given person or household, the duration of residence on the base would need to be ascertained. To assess potential exposure of that person or household to spe- cific contaminants in the water supply, more accurate information on the location and period of residence would need to be ascertained. Information on the population size or typical duration of residence of per- sonnel assigned to barracks was not available. Potential exposures in nonresidential settings should also be considered. Such exposures may oc- cur in schools and job locations on the base. Table 2-15 presents potential sites of nonresidential exposure to contaminants from the Tarawa Terrace and Hadnot Point water systems in 1943-1985. No information was available on the number of persons in occupational, school, or day-care settings with potential expo- sure to contaminated water.

OCR for page 28
Exposure to Contaminants in Water Supplies at Camp Lejeune 63 EXPOSURE ASSESSMENT IN STUDIES OF HEALTH EFFECTS OF WATER-SUPPLY CONTAMINATION AT CAMP LEJEUNE ATSDR has completed two epidemiologic studies of water-supply contamination at Camp Le- jeune (ATSDR 1998; Sonnenfeld et al. 2001). They focused on prenatal outcomes, including mean birth weight, small for gestational age, and preterm birth. The studies were limited to singleton live-born in- fants (with estimated gestational ages of 20 weeks or more) whose mothers resided in base housing for at least 1 week before giving birth in January 1, 1968-December 31, 1985. The earlier study (ATSDR 1998) also included stillborn infants. The results of those studies are presented in Chapter 8, and this section briefly summarizes the exposure assessments that were used in each. The 1998 ATSDR study evaluated residents of Tarawa Terrace and Hadnot Point, whereas the 2001 Sonnenfeld et al. study evaluated only residents of Tarawa Terrace. In both studies, exposure was defined by place of residence at delivery and ascertained by linking birth records to the base’s family- housing records. In the ATSDR study, residents of trailer parks were excluded because of the incompleteness of housing information and the inability to identify their water source. Infants whose mothers resided at Ta- rawa Terrace for at least 1 week before giving birth were classified as exposed. Also included in the ex- posed group were infants whose mothers received water from the Hadnot Point water system in the Hos- pital Point housing areas or resided in the service area of the Holcomb Boulevard water system and were pregnant for at least 1 week in a 12-day period in January 27-February 7, 1985. During that period, Had- not Point water served or was present in the Holcomb Boulevard system for operational reasons. Infants whose mothers were residents in other base family housing (the Marine Corps Air Station, Rifle Range, and Courthouse Bay housing areas) were classified as unexposed, as were infants whose mothers lived in areas served by the Holcomb Boulevard water system (defined as Berkeley Manor, Midway Park, Para- dise Point, and Watkins Village housing areas) during the study period other than the 2-week period in winter 1985 when the Holcomb Boulevard system received contaminated water from the Hadnot Point TABLE 2-15 Potential Sites of Nonresidential Exposure to Contaminants in the Tarawa Terrace and Hadnot Point Water Systems, 1943-1985 Exposure Scenario Years Contaminated Employment at Hadnot industrial area or other workplace Unknown-1985 Employment location served by Tarawa Terrace water system 1957-1985 Tarawa Terrace Elementary School 1957-1985 Tarawa Terrace day care 1957-1985 Hadnot Point-Holcomb Boulevard area schools Until 1972; intermittent linkages with the Hadnot  Russell School, 1943-1987 Point system; and during a 2-week period in 1985  Old high school/middle school, 1963-1987  Berkeley Manor Elementary School, 1963-present  Stone Street Elementary School, 1959-present  Midway Park Elementary School, 1952-present Until 1972; intermittent linkages with the Hadnot Hadnot Point-Holcomb Boulevard area day-care services  New hospital, 1983-1987 Point system after 1972; and during a 2-week period in 1985  Building 712, 1966-1982  Building LCH4025, 1960-1987  Building 799, 1953-1987  Building 2600, unknown-1987  Building 899, 1985-1987  Building 1200, 1942-1987 Source: Marine Corps, personal commun., December 4, 2007.

OCR for page 28
Contaminated Water Supplies at Camp Lejeune—Assessing Potential Health Effects 64 system. ATSDR also computed the number of weeks that a mother lived in the residence specified on the birth certificate on the basis of information about occupancy dates from the housing records, which were then categorized and used in analyses to explore the effects of duration of exposure on the adverse preg- nancy outcomes that were under investigation. However, ATSDR discovered after the study was com- pleted that the Holcomb Boulevard water-treatment plant had been in operation since 1968 (rather than 1972), so pregnant mothers receiving water from that system in 1968-1972 were incorrectly classified as “unexposed.” A reanalysis to correct that error is planned; exposure estimates from the water-modeling study (http://www.atsdr.cdc.gov/HS/lejeune/erratum.htm) will be used. In the Sonnenfeld et al. study, infants born to mothers living at Tarawa Terrace for at least 1 week before delivery were classified as exposed. With the exception of people who were excluded because they lived in base trailer parks or in areas served by distribution systems outside Tarawa Terrace that were also contaminated with TCE, all other infants whose mothers resided in base family housing were classified as unexposed. Misclassification of women as unexposed if they resided in areas served by the Holcomb Boulevard water system and were pregnant in 1968-1972 also affected this study. For each birth, length of maternal residence at Tarawa Terrace before delivery was computed by using dates of occupancy from the housing records and then categorized and used as another surrogate of exposure to explore effects on prenatal outcomes. Given the nature of the contamination at Camp Lejeune, the committee found the application of broad classifications of exposure based on place and duration of residence to be an appropriate approach for assessing exposure in the studies described above. Historical reconstruction and groundwater model- ing at Tarawa Terrace have provided additional characterization of potential exposure to PCE and an es- timated timeframe for the contamination, but it is questionable whether the additional information im- proves the exposure assessment for epidemiologic studies. Retrospective data on time-activity patterns of water use and water-related behaviors could improve exposure assessment but will be of questionable accuracy because the assessment is for periods that extend 20 years or more into the past. CONCLUSIONS The Tarawa Terrace and Hadnot Point water supply systems were contaminated with VOCs— particularly TCE, PCE, and DCE—for decades ending in the middle 1980s. Most of the organic contami- nants originated from DNAPLs, which have the potential to contaminate large volumes of groundwater over long periods. The hydrogeologic data indicate a high potential for contaminants from surface sources to migrate to water-supply wells in some areas of the base. The absence of a continuous impermeable bar- rier between the surface (source area) and the Castle Hayne aquifer (primary aquifer) supports the field observations that show contaminants in deep monitoring wells at the same depth as the water-supply wells. The exact extent of the contamination at Camp Lejeune cannot be documented with certainty, but it is known that a few highly contaminated wells supplied water to the Tarawa Terrace and Hadnot Point systems and that the contaminated wells were in operation for multiple years. The contaminant concentra- tions in the water-supply system varied because well pumping was cycled (the contaminated wells were not operated continuously, so there were fluctuations in contaminant concentrations). The qualitative evi- dence suggests that the magnitude of groundwater contamination was much higher in the Hadnot Point system than in the Tarawa Terrace system. It is also known that the Hadnot Point system supplied water to the Holcomb Boulevard water-supply area before 1972 and periodically after 1972. Widespread water- supply contamination in other water systems on the base was not evident from available documentation, but the committee’s review was too limited to be conclusive in this regard. The fundamental problem in estimating exposure to contaminants in the water-supply systems of Tarawa Terrace and Hadnot Point quantitatively is the lack of information on water quality and treatment- system operation during the period of contamination. There are no water-quality data for the period before the 1980s, and this leaves a 40-year period for which the extent of water-supply contamination is un-

OCR for page 28
Exposure to Contaminants in Water Supplies at Camp Lejeune 65 documented. In addition, little documentation is available on water-treatment techniques, which would shed light on the efficiency of contaminant removal during treatment. Also lacking is information on well cycling, which is important for documenting when contaminated wells were pumping raw water into the system. For those reasons, any estimates of water-supply contamination must rely on unverifiable as- sumptions. ATSDR applied best practices and cutting-edge modeling approaches to predict the complex groundwater-contamination scenario at Tarawa Terrace. The ultimate outcome of the modeling was aver- aged monthly predictions of the concentrations of contaminants in the water supply to which people could have been exposed. Although ATSDR recognized and tried to account for the limitations and uncertain- ties associated with developing its models, it is extremely difficult to obtain quantitative estimates of his- torical levels of exposure to PCE and its degradation products reliably on a monthly basis. Reporting such model predictions without clear error bounds gives the impression that the exposure of former residents and workers at Tarawa Terrace during specific periods within a given year can be accurately defined. It is the committee’s judgment that ATSDR’s model is suitable only for estimating long-term exposure quali- tatively. From that perspective, a single exposure category of “exposed” appears to be applicable for per- sons residing or working at Tarawa Terrace at any time during 1957-1985. Efforts at historical reconstruction of exposures at Hadnot Point will be even more problematic. The contamination scenario at Hadnot Point is so complex that the committee judges that only crude es- timates of contaminant concentrations in the water supply can be obtained. RECOMMENDATIONS The history of water-supply contamination at Hadnot Point is much more complex than the his- tory of that at Tarawa Terrace because of the multiplicity of sources and contaminants and the ill-defined period of contamination. Therefore, the committee recommends the use of simpler approaches (such as analytic models, average estimates based on monitoring data, mass-balance calculations, and conceptually simpler MODFLOW/MT3DMS models) that use available data to rapidly reconstruct and characterize the historical contamination of the Hadnot Point water-supply system. Simpler approaches may yield the same kind of uncertain results as complex models but are a better alternative because they can be per- formed more quickly and with relatively less resources, which would help to speed-up the decision- making process. As needed, and if available, better field characterization and details (such as active supply wells and cycling schedules, geologic data, and source characteristics) may be added to the conceptual models to improve understanding of transport at selected locations where potential exposure was high. Detailed MT3DMS modeling studies should be performed only for selected sites (using locally-refined grids) and only after establishing a priori the clear need, objectives, and expected outcomes for such studies. On the basis of the results of the Tarawa Terrace models, application of cutting-edge research codes for ground- water modeling (such as PSOpS and TechFlow) is unlikely to reduce uncertainty in the Hadnot Point ex- posure scenarios, which are expected to be much more complex than at Tarawa Terrace. Future modeling efforts should also be aided by additional field information about the physical and chemical characteristics of the sources and receptors (aquifers). Specifically, the hydrogeologic char- acterization of the recharge zones of the primary aquifer that was and is the source of water for the water- supply systems at Camp Lejeune should be determined. For example, the extent and characterization of the Castle Hayne confining unit are critical for understanding the potential for hydraulic connectivity be- tween the waste sites identified and the source aquifer for the water-supply wells over the period of poten- tial exposure (1943-present). It is well documented that the confining layer is neither continuous nor con- fining in all areas beneath the Camp Lejeune geographic boundary. The committee’s effort to evaluate potential exposures to contaminants in the Tarawa Terrace and Hadnot Point water systems was hampered by the fact that the available data on water quality of those systems was found in hundreds of documents. Most of the documents are publicly available on line, but

OCR for page 28
Contaminated Water Supplies at Camp Lejeune—Assessing Potential Health Effects 66 they were not readily searchable or cataloged in an organized fashion for research. To facilitate future exposure-assessment efforts, the committee strongly recommends that a comprehensive, accessible data- base of water-quality measurements (including data from remedial investigations) be created and main- tained. Such a database should include information on sample location, date, analytes measured, labora- tory quality-control information (including limits of detection), and other information relevant to exposure assessment that relies on environmental samples collected in the course of investigating water, soil, and air quality at Camp Lejeune. Because of the sparseness of water-quality data and the insufficient ability of water-quality mod- eling to make up for the absence of information, most exposure estimates in epidemiologic studies at Camp Lejeune will rely heavily on unverifiable assumptions and projections. Therefore, the most useful exposure assessment will likely be relatively crude and based for the most part on ascertaining the most likely time period and location (water supply system) of contamination, typical locations the study par- ticipant spent time on the base (for example, residence, school, daycare, workplace), and crude categori- zation of personal water-use activities during the exposure period.