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PUBLIC HEALTH ASSESSMENT

U.S. ARMY UMATILLA DEPOT ACTIVITY
HERMISTON, UMATILLA COUNTY, OREGON


EVALUATION OF ENVIRONMENTAL CONTAMINATION, EXPOSURE PATHWAYS, AND THE PUBLIC HEALTH IMPLICATIONS

Introduction

Exposure, or contact, drive the ATSDR public health assessment process. Chemical contaminants disposed or released into the environment at the facility have the potential to cause adverse health effects. However, a release does not always result in exposure. People are exposed to a chemical only if they actually come in contact with the chemical. People may be exposed by breathing, eating, or drinking a substance containing the contaminant or by skin (dermal) contact with a substance containing the contaminant.

Exposure does not always result in adverse health effects. The type and severity of health effects that may occur in an individual from contact with a contaminant depend on the exposure concentration (how much); the frequency and/or duration of exposure (how long); the route or pathway of exposure (breathing, eating, drinking, or skin contact); and the multiplicity of exposure (combination of contaminants). Once exposure occurs, characteristics such as age, sex, nutritional status, genetics, life style, and health status of the exposed individual influence how the individual absorbs, distributes, metabolizes, and excretes the contaminant. These factors and characteristics determine the health effects that may occur as a result of exposure to a contaminant.

In this section we evaluate the possible pathways of exposure to contamination at the former UMDA. ATSDR examined the possible exposure situations to determine whether people in the community are exposed to (or in contact with) the contamination.

I. No Public Health Hazard Situations

As a result of our site visit observations, and a review of the available data, we concluded that there are no plausible exposure situations that could pose a public health hazard at this time because people are not exposed to hazardous chemicals. Hazardous chemical contaminants (primarily explosive ordnance chemicals and metals) have been found in soil and shallow groundwater at the facility. Also, because of the nature of activities occurring at the ammunition disposal area (ADA), it is likely that undiscovered unexploded ordnance (UXO) may still exist in this area. However, the eight OUs, as described in Table 1, do not present hazards to public health, in that there is no past, current or likely future potential for the public to be exposed to the contaminants. Table 2 summarizes our evaluation.

Table 2 -- Pathways Evaluation Table

Table 2 - UMCD - No Apparent Public Health Hazard Situations -
PATHWAY
NAME
CONTAMINANT
POTENTIAL EXPOSURE PATHWAY ELEMENTS
TIME
COMMENTS
SOURCE
ENVIRONMENTAL
MEDIA
POINT OF
EXPOSURE
ROUTE OF
EXPOSURE
POTENTIALLY
EXPOSED
POPULATION
Ammunition Demolition Area UXO and Explosive ordnance chemical contamination disposed ordnance ADA (OU4) soil onsite soil and physical hazards
(UXO)
dermal, physical hazard Oregon National Guard future Adverse effect from dermal exposure to contaminated soil not likely to result from incidental contact with the relatively low levels detected in soil.

Site not currently actively used. Not likely that health hazard will result if soil remediation occurs as planned, and providing Guard is briefed on the potential for UXO to be found in ADA.

Groundwater explosive
ordnance
chemicals
washout lagoon
(OU 3)
groundwater domestic water supplies (onsite supply wells and offsite private wells) ingestion, incidental inhalation and dermal onsite users future Exposure unlikely - facility water supply wells are located in deeper aquifer and are not in pathway of plume.
offsite users future Exposure unlikely - plume has not reached site boundaries. Groundwater remediation will further reduce potential for migration of plume offsite.
Soil contamination metals and explosive ordnance chemicals deactivation furnace (OU1),
washout lagoon
(OU2),
misc. sites (OU5),
washout plant (OU6)
soil onsite surface soil dermal unspecified future users future Incidental contact with contamination remaining post-remediation not likely to be a health hazard, if cleanup progresses as planned. If (when) attained, cleanup levels will be adequate to protect any future site users (future use calls for wildlife management areas and industrial development in the areas currently being remediated.)

A. Groundwater

The shallow groundwater under the facility is contaminated as the result of explosive ordnance chemicals percolating into the aquifer from the Washout Lagoons (OU3). Shallow groundwater moves generally southeast in this area. Figure 3 shows the approximate location of the plume. Table 1 lists the contaminants of concern. The contaminated aquifer is estimated to be at an approximate maximum depth of about 125 to 135 feet below ground surface. This groundwater is being monitored by onsite monitoring wells (for contaminants including explosive ordnance chemicals and metals) (2).

Onsite drinking water is supplied by a system of seven wells, all located in an uncontaminated aquifer below the one in which the plume is located. The water supply wells are completed in an aquifer located at about 300 to 320 feet below ground surface. In this area, the general direction of flow for this deeper aquifer is to the southeast. There is no evidence that the shallow aquifer is hydraulically connected to the deeper one, so that contamination of wells completed in the deeper one is unlikely (17). To verify that these wells were not contaminated, onsite production wells were tested in two rounds of sampling (November, 1990 and March 1991). The analyses of these samples did not show evidence of contamination from facility-related hazardous chemicals (12).

The supply wells are located at considerable distances from the current location of the plume. The closest supply wells, #1 and #2, are located in the administration area, about one mile from the plume. Well #3 is located across gradient from the southeast flowing plume, about one mile west of the current plume location. Wells #4 and #5 are located in the southwest corner of the facility, about three miles from the plume location. Wells #6 and #7 are located on the northern boundary of the facility, well upgradient from the plume (17). Figure 3 shows the approximate locations of these wells relative to the contaminant plume. Water from the supply wells is not currently (the most recent analysis was conducted in 1991) analyzed for explosive ordnance chemical contaminants.

The closest offsite wells are located about 1 1/2 miles to the south of the plume. These wells, located in a former post housing area about 1/4 mile south of the facility boundary, were formerly part of the facility water system and are believed to be completed in the deeper aquifer (13). Because of their distance from the facility groundwater plume and because of the completion depth, these offsite wells are not likely to be subject to contamination from this source.

Figure 3
Figure 3 - UMDA Water Supply Well Locations

Remediation plans, as described in the Record of Decision (ROD), call for "pump and treat" activities to reduce explosive ordnance chemical contamination (12). This activity began in January 1997. Table 1 presents the proposed clean-up levels and ATSDR's comparison values for drinking water.

At this time, groundwater contamination from the washout area does not present a public health hazard onsite, has not reached offsite and is not accessible to offsite private or public water supplies. If additional groundwater development is included in future use plans, it would be necessary to perform and evaluation of the water in the shallow aquifer to determine its suitability for the proposed uses.

B. UXO and Soil Contamination at the ADA

Soil in the ADA have been found to be contaminated by metals and explosive ordnance chemicals (15). Low levels of metals and explosive ordinances chemical are not easily taken into the body via dermal contact. Additionally, short term incidental exposure to low levels via inhalation or ingestion of contaminated dust is not likely to result in a health hazard. The levels of these contaminants detected within the ADA do not currently represent a health hazard from the type of incidental dermal contact or dust inhalation/ingestion that remediation workers or Oregon National Guard (ORNG) trainees might experience onsite. Soil with contaminants exceeding levels of concern as determined by EPA and the state (Table 1) will be removed (15).

Remedial Investigation activities have revealed buried unexploded ordnance (UXO) within the ADA (15). As a part of the remedial activities at ADA, a surface clearance for UXO was conducted in 1996. UXO discovered during the clearance operation was removed by trained personnel as required by the ROD (15). Projected reuse plans call for use of this area by the ORNG for small arms training. ORNG personnel should be adequately trained in the hazards of UXO so that the potential for discovery of additional UXO will not present an unreasonable hazard.

Additionally, undiscovered UXO is not likely to present a public health hazard to the community, since access to this area is stringently restricted, both by fencing and signs and by security personnel. Access to the ADA is limited to remediation personnel and to military personnel involved in weapons training.

For these reasons, with the removal of UXO and when soils in the ADA are remediated to the planned levels, soil contamination and UXO at ADA will not present a public health hazard.

C. Other Soil Contamination Across the Facility

Contaminated soil and lagoon sludge are located in areas that are not open to public access. Table 1 and Figure 3 summarize these sites. These areas are undergoing remediation intended to reduce the contamination to levels that will not present a hazard to public health. The intended levels, when achieved, will be protective of human health (10,11,14,15,16), for the incidental dermal exposures that would be the most likely exposures in the future use scenarios proposed. Incidental exposure to low levels of metals or explosive ordnance chemicals via infrequent incidental dermal contact or incidental inhalation or ingestion of contaminated dust are not likely to present public health hazards.


Summary of Future Use Plans

As a part of DOD BRAC program, UMCD was realigned. Although no transfer of land will be made until the chemical weapons stored at UMCD are destroyed, current plans call for the facility to be made available for wildlife management, agriculture, commercial and industrial use, with the ADA being turned over the ORNG sometime after 2004 (2,3,7).

The primary concern to be addressed is the potential for exposure to contamination that might remain after the facility is transferred from U.S. Army control and is available for public use. At present the final disposition of the land occupied by the facility has not been decided. Although clean-up levels have been set by the facility and the regulators, the actual post-remediation levels of contaminants cannot be anticipated by this evaluation.

The remediation goals set by EPA and ODEQ in the UMCD Records of Decision (RODs) are sufficient to be protective of public health for the uses currently anticipated (8,9,10,11,12,14,15,16). The ROD requires groundwater monitoring is to be conducted to determine the effectiveness of the remedial activities. This monitoring should include analysis of any onsite water supplies. Also, it will be necessary to evaluate the potential for public health hazard possible from exposure to any remaining soil contamination levels (as determined by post-remediation verification analyses) when the usage is decided and the final contaminant levels are known.

QUALITY ASSURANCE AND QUALITY CONTROL

ATSDR relies on the information provided in the referenced documents to prepare this public health assessment. The agency assumes that adequate quality assurance and quality control measures were followed with regard to chain-of-custody procedures, laboratory procedures, and data reporting. The validity of the analyses and the conclusions drawn in this document are determined by the availability and reliability of the referenced information.

The majority of the environmental data presented in this public health assessment is from the Remedial Investigation (RI) preliminary data. Generally, the methodology used in the RI activity is appropriate for characterizing contamination at the facility. Additional information collection is planned during completion of RI activities. This information will be evaluated by ATSDR. Conclusions and recommendations of this PHA will be modified if appropriate and necessary.

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