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PUBLIC HEALTH ASSESSMENT

IOWA ARMY AMMUNITION PLANT
MIDDLETOWN, IOWA


SUMMARY

Iowa Army Ammunition Plant (IAAAP) is an active 19,015-acre load, assemble, and pack (LAP) munitions facility in Middletown, Iowa. It lies in a rural agricultural area, surrounded by active corn and soybean farms and several hundred occupied residences. Since IAAAP operations began in 1941, the installation has used explosive materials and lead-based initiating compounds to produce projectiles, mortar rounds, warheads, demolition charges, anti-tank mines, and anti-personnel mines. From 1948 to 1975, the Atomic Energy Commission operated a portion of IAAAP to assemble nuclear weapons. Current LAP activities operate several production lines.

IAAAP was placed on the U.S. Environmental Protection Agency (EPA) National Priorities List in 1990, primarily because of contamination detected in groundwater and surface water. The primary contaminant of concern at this installation is hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), although other explosives, metals, volatile organic compounds, semi-volatile organic compounds, and radionuclides have been detected on the installation at levels above the Agency for Toxic Substances and Disease Registry (ATSDR) health-based comparison values. This public health assessment specifically addresses non-nuclear contaminants of concern. However, in response to recent community concerns regarding historical nuclear weapons operations, the Department of Energy and others are gathering additional data and information. When sufficient information becomes available, ATSDR will evaluate potential pathways of environmental exposure to radionuclides contamination at IAAAP and disclose its findings.

Community members have expressed concern about potential health effects associated with contaminants in groundwater, surface water, soil, sediment, locally-grown agricultural produce, local deer, and local cattle. ATSDR conducted a site visit in May 1998 and identified no immediate public health hazards.

ATSDR performed a thorough review and evaluation of available groundwater data. RDX was detected in groundwater beneath IAAAP and off site, particularly south and southeast of military property. Five wells are located on site, but no one has ever used on-site groundwater as a source of drinking water (Hicks, 1999). Beginning in the 1980s, periodic monitoring of nearby private wells indicated that the water used by some local residents in the past did contain low levels of RDX. Past exposures, however, were minimized by aggressive Army efforts to provide bottled water and alternative drinking water sources to impacted individuals. In areas south and southeast of the installation potentially affected by off-site groundwater contamination, the Army connected residences to Rathbun Rural Water System drinking water, which is filtered and treated to meet all state and federal drinking water standards. In off-site areas where people may have ingested RDX-contaminated groundwater at levels above health-based guidelines, ATSDR determined that no apparent public health hazards exist due to short durations of exposure, low exposure doses, and/or remediation efforts by the Army. In addition, RDX concentrations in groundwater are apparently diminishing due to Army remediation efforts, natural attenuation, and/or natural dilution factors. To ensure continued delivery of safe drinking water, IAAAP has agreed to continue testing on- and off-site monitoring and production wells and to supply alternate drinking water sources should it become necessary in the future. For these reasons, ATSDR concludes that past consumption of groundwater poses no apparent public health hazard; present and future consumption poses no public health hazards.

Discharges from IAAAP operations have contaminated on-site and off-site surface waters. Two watersheds, Brush Creek and Skunk River, have received the most contamination. ATSDR's review of surface water data found that trinitrotoluene (TNT) may have historically been a contaminant of concern. No available data exist, however, to quantify past TNT or RDX contamination levels. At the present, almost all surface waters accessible to the public appear uncontaminated, with RDX being the primary contaminant of concern in limited areas. Current RDX concentrations are at or slightly above EPA's lifetime health advisory levels for drinking water. Because no one drinks this surface water and only minimal exposures, if any, may occur via incidental ingestion and dermal contact from swimming or wading in the water, no public health hazards exist. Moreover, RDX concentrations in surface water continue to decrease due to Army remedial activities, natural attenuation, and/or natural dilution factors. It is unlikely that surface water was a public health hazard in the past but, because of the lack of data, ATSDR concludes that past exposure to IAAAP-area surface water poses an indeterminate public health hazard. Current and future exposures to IAAAP-area surface water pose no apparent public health hazards.

Forty-four sites at IAAAP were investigated for potential soil and sediment contamination, 33 of which were evaluated in detail by ATSDR due to their potential to impact underlying groundwater or to be accessed by the general public. At all 44 sites, ATSDR concluded that soil and sediment contaminants do not pose a public health hazard because either 1) publicly -accessible areas contain contaminant concentrations too low to pose health hazards; 2) exposure (past, present, and future) to the general public has been prevented; and/or 3) remedial activities have reduced or will reduce contaminant concentrations to levels that pose no public health threat. ATSDR concludes that past, current, and future exposures to IAAAP soil and sediment pose no public health hazards.

Lastly, ATSDR reviewed data on explosives uptake in agricultural produce, deer, and cattle to address community concerns about the safety of consuming local crops, venison, and beef. Toxicologic and ecological studies indicate that IAAAP crops are not bioaccumulating RDX and that they are safe for human consumption. In addition, studies at other Army facilities and laboratory studies suggest that deer and cattle do not bioaccumulate RDX in their tissue. ATSDR concludes that past, present, and future consumption of local biota poses no public health hazards.


BACKGROUND

Installation Description and History

The Iowa Army Ammunition Plant (IAAAP) is a load, assemble, and pack (LAP) munitions facility that began production in 1941 and continues to operate as a Government-owned, contractor-operated installation. IAAAP is located in the southeastern part of Iowa, near the town of Middletown, Des Moines County. It lies about 10 miles west of the Mississippi River and Burlington (Army, 1988). Less than a third of the IAAAP's 19,015-acre (30-square-mile) property is occupied by active or formerly-active production or storage facilities. The remaining land is evenly divided between leased agricultural acreage and woodlands (ACE, 1997a, 1998a).

Since 1941, IAAAP has produced projectiles, mortar rounds, warheads, demolition charges, anti-tank mines, and anti-personnel mines, but only a few production lines currently remain in operation. Components of these munitions, including primers, detonators, fuses, and boosters, have also been handled at the facility, primarily in the 1960s and 1970s. These LAP operations required use of explosive materials and lead-based initiating compounds (JAYCOR, 1994, 1996).

From 1948 to 1975, a portion of the installation (Line 1) was modified and operated by the U.S. Atomic Energy Commission (AEC) (later the Energy Research and Development Administration) (DOE, 1999). AEC added numerous facilities within Line 1 (Dames and Moore, 1989), but due to the nature of the AEC operations, little information is currently available on past Line 1 activities. It is known, however, that nuclear weapons were assembled at Line 1 using several high explosives and that radioactive materials were "received in a sealed configuration and were swipe tested for leaks before use" (JAYCOR, 1996; DOE, 1999).1

Over the years, some IAAAP operations led to contamination of on-site waters and soils. The primary source of contamination at IAAAP may be attributed to past operating practices where explosives-contaminated wastewater and sludge were discharged to uncontrolled lagoons and impoundments on site (CDM, 1996; Environmental Research Group, Inc., 1982). Discharges and emissions also arose from areas where IAAAP burned explosives, conducted detonation tests, and disposed of miscellaneous solids. Other activities related to the operation and maintenance of IAAAP have resulted in fuels, solvents, and pesticides contamination.

On-site landfilling operations began in 1941 when IAAAP was constructed and continued until 1992. The Inert Landfill covers approximately 17 acres in the east-central portion of IAAAP. The landfill received materials such as residential and cafeteria refuse and garbage, plastic, tin cans, scrap lumber, empty fiber drums (crushed), unsalvageable paper and cardboard, and asbestos insulation (in double plastic bags). For several years in the early 1980s, a small portion of the landfill received other wastes, such as ash from the open burning of the contaminated waste processor, the explosive waste incinerator, and explosives and explosive-contaminated wastes (CDM, 1997). In 1994, this area (known as Trench 5) underwent closure pursuant to Resource Conservation and Recovery Act Hazardous and Solid Waste Amendments (RCRA) guidelines.

The principal installation contaminants are explosives. Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is currently the explosive of greatest potential concern to public health, but, historically, trinitrotoluene (TNT) may have been the most prevalent explosive. Pesticides, fuel products, volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), and metals are also present in some on-site areas. Most of the contamination is contained within the industrial areas of IAAAP property, although some explosive-related contamination has migrated off site via groundwater and surface water (ACE 1997b,c). Surface water is the primary off-site migration pathway for IAAAP contaminants. The facility is drained by three primary creeks: Brush, Spring, and Long Creeks. Several small, unnamed creeks drain the southern and southwestern periphery of IAAAP. This drainage is intercepted by the Skunk River and flows east, towards the Mississippi River. A small area in the northern portion of IAAAP (Yard L) drains into the Little Flint Creek Watershed.

Remedial and Regulatory History

Beginning in 1975 and continuing to the present, numerous investigations have been conducted by the Army, U.S. Environmental Protection Agency (EPA), and Army contractors to investigate on- and off-site environmental contamination resulting from IAAAP operations. In 1980, a Preliminary Assessment and Site Investigation (PA/SI) was conducted at IAAAP. Pursuant to the RCRA of 1984, EPA completed an assessment of the facility in 1987 and reported that releases had occurred. In 1986, EPA conducted a RCRA Facility Assessment. Limited sampling was performed and contamination was discovered at active and former hazardous waste treatment, storage, and disposal sites (EPA, 1991).

Primarily due to surface water contaminated with explosives leaving the installation boundary, IAAAP was proposed for EPA's National Priorities List (NPL) in August 1989 and listed in August 1990. On December 10, 1990, a Federal Facilities Agreements (FFA) between EPA and the Army became effective to clean up the installation. The FFA provides a framework for the investigation and cleanup of contamination at IAAAP.

In 1991, a subsequent PA/SI identified 44 sites of possible contamination. Of the 43 sites, 33 required further studies. In 1992, Remedial Investigation and Feasibility Study (RI/FS) activities began. To facilitate installation cleanup activities, the installation was divided into three Operable Units (OUs):

  • Soils OU (OU #1)--addresses contamination in the soils.
  • Groundwater OU (OU #3)--addresses contamination of groundwater within the IAAAP boundaries and potentially off-site contamination.
  • Installation-wide OU (OU #4)--addresses institutional controls, previously unaddressed areas of soil contamination, VOC-contaminated media, ecological risks, long-term monitoring requirements, and any other unacceptable risks which may be identified and not addressed in either OU #1 or OU #3.

OU #2 was originally established for the non-time critical (NTC) soils removal actions. It was subsequently merged into OU #1 for simplicity and completeness (ACE, 1998b,c).

After dividing the installation by OUs, the Army conducted investigations to better characterize contaminated media in the vicinity of IAAAP. In 1993, the installation completed supplemental subsurface soil and groundwater studies for the RI/FS. Results of the RI were documented in the report Revised Draft Final Remedial Investigation/Risk Assessment, Iowa Army Ammunition Plant, Middletown, Iowa (JAYCOR, 1996). In August 1996, the Army performed a installation-wide hydrogeologic evaluation at IAAAP to identify data gaps pertaining to groundwater and to recommend studies to address the data gaps. The draft Basewide Hydrogeologic Evaluation was submitted in November 1996. In late 1996, the Army conducted a supplemental RI aimed at addressing the identified data gaps. The final Work Plan and Sampling and Analysis Plan was submitted in April 1997 and field work was completed during the Spring and Summer 1997. Currently, the study looking at soil cleanup options is nearing completion and several removal actions are in progress (see Ongoing/Planned Soil Actions in the Public Health Action Plan section). Detailed summary reviews of most of these above investigations can be found in the Revised Final Draft Remedial Investigation/Risk Assessment for IAAAP (JAYCOR, 1996).

In general, however, past IAAAP investigations consistently revealed that two areas, the former Line 1 Impoundment and the Line 800 Pinkwater Lagoon, were the most contaminated locations on site (CDM, 1996; Dames and Moore, 1989). Both areas had the potential to leach contaminants into underlying groundwater. The migration of contaminated groundwater to nearby residential drinking water wells was once considered the greatest potential risk to human health by the Army and EPA (CDM, 1996). Thorough characterization of on- and off-site groundwater contamination, however, indicates that IAAAP-related contamination does not appear to threaten human health. ATSDR further discusses groundwater and other site-related health issues in the "Exposure of Environmental Contamination and Potential Exposure Pathways," Table 2, and Appendix A of this report.

Demographics and Land Use

To characterize the local population and identify the presence of sensitive subpopulations, such as young children, ATSDR examines the demographics of the nearby communities. This information also provides detail on residential history in a particular area that helps ATSDR assess time frames of potential human exposure to contaminants. The demographic and housing data for IAAAP and the surrounding areas, particularly the areas south of the installation where groundwater contamination has migrated, are presented in this section.

IAAAP and Local Area Population and Housing Data

The demographic setting of IAAAP is characterized as rural. According to the 1990 U.S. Census, approximately 30% of the 42,600 Des Moines County residents live in rural areas, with a farm population of 1,571 (U.S. Census, 1990). Approximately 1,727 individuals (in approximately 769 housing units) reside within 1 mile of the installation. The most important population centers--in terms of size--are the towns of Burlington (population approximately 28,000), West Burlington (population approximately 3,000), Middletown (population approximately 400), Fort Madison, and Danville (Dames and Moore, 1989).

Because of IAAAP's rural demographic setting, relatively few people might potentially be exposed to installation-related contaminants. Prior to 1997, approximately 43 on-site housing units were used by contract personnel and their families. Located outside of the secured fence and more than 1,500 feet from the nearest site under investigation (JAYCOR, 1996), these houses were transferred by the Army to the city of Middletown in October 1997. The rural area south (downgradient) of IAAAP is sparsely populated. Approximately 50 people live in Augusta, an unincorporated town approximately 1 mile from the south-southwestern boundary along the Skunk River. The most populated area to the south is Fort Madison which is approximately 10 miles to the south of IAAAP.

Land Use in the IAAAP Area

Land use on the IAAAP property consists of administrative and industrial operations (approximately 4,000 acres), leased agricultural use (approximately 7,750 acres), and forested land (approximately 7,500 acres). Some cow pasturing takes place in munition storage yards (ACE, 1998a). Crops grown in the area consist mostly of corn and soy beans.

Public access to the installation is restricted by contractor security measures, including perimeter fencing, but various recreational activities are allowed in some non-industrial, on-site areas. These recreational activities include hunting and fishing. Public access to many on-site contaminated areas, however, is prevented by secondary fencing surrounding installation facilities and industrial areas.

The groundwater aquifers directly underlying IAAAP do not supply any production wells for drinking water purposes (Hicks, 1999). Off site, however, the groundwater aquifers supply private production and irrigation wells. The nearest municipal wells are over 3 miles away and have not been impacted by IAAAP-related contamination, nor do they appear at-risk for future contamination from installation-related contaminants.

On-site surface water is not currently an integral part of IAAAP operations. Prior to 1977, however, IAAAP's primary drinking water source came from Long Lake (now known as Mathes Lake) and was treated at an on-site water treatment facility. In accordance with the State of Iowa Surface Water Quality Criteria, surface waters in the vicinity of IAAAP are no longer used as drinking water. In the past, several on-site creeks received untreated facility wastewater and explosives discharge from IAAAP. Currently, and in accordance with the National Pollutant Discharge Elimination System Permit signed with the state of Iowa, treated wastewater from the plant is discharged into Brush Creek and Long Creek. Some surface waters on and near IAAAP are used for recreational activities, but these waters are uncontaminated.

ATSDR Activities

In May 1998, ATSDR conducted a two-day site visit at IAAAP and met with Army representatives. ATSDR toured IAAAP facilities with several Army employees, some Restoration Advisory Board (RAB) Committee members, and one representative from the local media. The group viewed all investigation sites and remediation efforts, as well as off-site agricultural farms and houses south, southwest, and southeast of the facility. According to ATSDR discussions with the Army and RAB Committee members, no area residents expressed any specific health concerns that they attribute to IAAAP (ATSDR, 1998).

After the site visit, ATSDR contacted several community members by telephone. These community members were contacted because they had previously expressed concern about IAAAP operations. According to Army and EPA reports, these concerned community members had asked about potential environmental and health impacts associated with groundwater, surface water, soil, sediment, and local biota contamination. During ATSDR's discussions with these individuals, however, no area residents expressed any specific health concerns attributed to IAAAP. Currently, some community members seem to be concerned about the community members' relationships with the Army and whether or not the Army would take responsibility for cleaning up the contamination for which it is responsible. Some community members did share their observations and concerns about past levels of contamination of surface water and groundwater in the area to the south-southeast of IAAAP.

Quality Assurance and Quality Control

In preparing this public health assessment, ATSDR relied on the information provided in the referenced documents. Documents prepared for the CERCLA and RCRA programs must meet specific standards for adequate quality assurance and control measures for chain-of-custody procedures, laboratory procedures, and data reporting. The validity of the analyses and conclusions drawn in this document are dependent upon the availability and reliability of the referenced information. The environmental data presented in this public health assessment are from Army and EPA reports; remedial site investigations of the RI/FS sites; quarterly groundwater monitoring data; and drinking and irrigation water data from IAAAP, municipal, and private wells.



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