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The Armour Road site is the location of a former herbicide blending facility that operated from approximately 1948 to 1986. It is located at 2251 Armour Road in North Kansas City, Clay County, Missouri, in a mostly industrial and commercial area. During its time of operation, the facility used various chemicals including arsenic, 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), pentachlorophenol (PCP), and sodium chlorate to produce herbicides used by the railroad for right-of-way weed control. Because of past activities and disposal practices, the on-site soil, building, and on-site and off-site groundwater have been contaminated, especially with arsenic. The site is restricted with a chain-link fence, but there is evidence that trespass is occurring to an unknown extent. In addition, a polypropylene geo-fabric and gravel cover placed over the contaminated on-site soil has been compromised to some extent. Exposure pathways at the site consist of inhalation of, ingestion of, and dermal contact with contaminated soil for the on-site trespasser, and the possibility of inhalation of contaminated dust off-site. If access could be eliminated and the polypropylene and the gravel cover properly maintained, current on-site and off-site exposure pathways could be eliminated. Presently, contaminated groundwater is not being utilized for potable water, but a number of industries and the city of North Kansas City (upgradient and side-gradient) use the aquifer for a water source.

Community public health concerns have not been found to be present at the site. The Missouri Department of Health held a public availability session on July 16, 1998 to determine if community health concerns exist.

Considering the exposure pathways and the high levels of contamination (especially arsenic), the site has been given the classification of Urgent Public Health Hazard. Exposure to arsenic at the levels on the site present an additional risk of cancer. Usage of the arsenic contaminated groundwater as potable water would also present an additional risk of cancer. We recommend that security of the site be improved and that the cover over the site be maintained to eliminate exposure. Access to the contaminated groundwater should also be prevented and remediation of the groundwater and the site be performed to eliminate any possible future exposure.


The Missouri Department of Health (DOH) is writing this public health assessment to address current, past, and future possible exposure to high levels of environmental contamination (primarily in soil and groundwater) at this site. This document will address past worker exposure, current public and trespasser exposures, and future exposures.


The Armour Road site is a former herbicide blending facility located at 2251 Armour Road, in North Kansas City, Missouri. The site consists of approximately 1.8 acres on the south side of Armour Road. There is one on-site 25,000 square foot building adjacent to Armour Road. The area in front and to the east of the building is covered with concrete, while the rest of the area has a gravel cover. In addition, a chain link fence surrounds the site (1).

The surrounding area is commercial to the north and west with predominately industrial areas, transportation terminals, manufacturing facilities, and heavy industry farther to the west. A residential area and hospital are upgradient and farther to the north, with the nearest residence approximately 700 feet north of the site. Immediately south of the site is a large railroad yard with industrial areas, transportation terminals, manufacturing facilities, and heavy industries farther south to the Missouri River. At the nearest point, the Missouri River is 0.75 mile to the southeast (1). See Figure 1.

From historical records dating back to 1948, the Armour Road facility has been operated by three companies until operations ceased in 1986. Herbicides generated by the facility were used to control weed growth along railroad right-of-ways. Railroad tracks from the adjoining railroad lines still lead into the building where railroad cars were brought inside for maintenance, repair, and loading/unloading. Chemicals used in the herbicide blending process included: arsenic, 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), pentachlorophenol (PCP), and sodium chlorate. Most of the equipment in the building was removed with the exception of two below-ground mixing vats and a below-ground trench used for servicing and unloading railroad cars ( Figure 2). The building reportedly has been closed and locked since operations ceased in 1986 (1). According to interviews with former employees, the business only had approximately five employees (2).

Extensive soil sampling has been conducted on-site and in the immediate area. Contamination of soil extends from the surface to the watertable (approximately 13 to 18 feet deep) and over much of the site. The most significant contaminants are arsenic, 2,4-D, PCP, and antimony with arsenic being the most widespread. The site seems to have several "hot spots" of arsenic contamination with the maximum discovered in surface soil (0-6 inches). Arsenic was found at 121,000 parts per million (ppm) near the southern end of the building in a 1996 sampling event. Levels in other areas were much lower and varied from 3.8 ppm to 27,000 ppm. Arsenic concentrations decreased with depth, with a maximum subsurface level of 6,800 ppm at the 15 foot depth. Other soil contaminants found above the Agency for Toxic Substances and Disease Registry's (ATSDR's) Environmental Media Evaluation Guide (EMEG) or the Missouri Department of Health's (DOH's) Any-Use Soil Levels (ASLs) at their maximum level included: antimony (9,650 ppm), lead (16,500 ppm), mercury (156 ppm), thallium (1,360 ppm), benzo(a)pyrene (24 ppm), cadmium (2,200 ppm), 2,4-dichlorophenol (258 ppm), and PCP (250 ppm), (See Table 1) (1,3).

Contamination found in the building's concrete, floor tiles, and other building materials consisted of arsenic ranging from zero to 6,000 ppm, 2,4-D from zero to 1,500 ppm, and 2,4,5-T from zero to 120 ppm (1). The building has also become inhabited by pigeons, and reportedly the floor is layered with droppings.

Groundwater in the area is used for municipal and industrial purposes. North Kansas City is served by a municipal public water system supplied by wells located 1.3 miles west of the site. These wells are located in the Missouri River alluvial aquifer and side-gradient/upgradient of the contaminated groundwater. Other wells in the area consist of industrial wells that are located side-gradient/upgradient of the site, with the exception of a contaminated off-site industrial well that was used for non-contact cooling. This well was closed in June 1995 after arsenic contamination was discovered. According to an extensive groundwater model developed by the United States Geological Survey in 1997, contaminated groundwater from the site is not expected to affect the wells west of the site, including the two largest pumping wells (North Kansas City Water Supply and National Starch & Chemical Co.) (1).

Groundwater contaminants are similar to those found in the soil (a complete list can be seen in Table 2). Soils at the site consist of silty clay with imbedded clay and sand lenses in the top 17 to 22 feet (4). The major groundwater contaminants found in shallow monitoring wells (between 15 to 20 feet deep) in this top layer of soil include arsenic and PCP. Different sampling events have shown varying levels of groundwater contamination. In a 1994 sampling, arsenic ranged from non-detectable to 2,060 ppm and PCP ranged from non-detectable to 8,062 ppm (5). In a 1995 sampling, arsenic ranged from 21.6 ppm to 1,669 ppm and PCP ranged from non-detect to 93.4 ppm. The highest concentration was found around the center of the site (1).

Beneath the silty clay soil is a fine to medium-grained sand that is expected to extend from approximately 22 feet to bedrock. Bedrock is thought to occur at a depth of approximately 60 to 85 feet below the site; however, this has not been confirmed. The depth to bedrock in the area surrounding the site averages 85 to 90 feet, but may be greater than 140 feet (1). Monitoring wells placed in the deeper sands (approximately 35 feet deep) found arsenic concentrations in groundwater ranging from 11 to 362 ppm. PCP ranged from non-detectable to 93.9 ppm (1).

Groundwater contamination has also been found off site (1). Groundwater is known to flow to the south and east toward the Missouri River. The industrial well (mentioned on previous page) downgradient of the site was found to have 1.67 ppm of arsenic in a March 1995 sampling. Previous samplings had shown 0.045, 0.428, and 2.16 ppm of arsenic. This well, located 0.25 miles downgradient from the site, was used in the past for non-contact cooling, but usage was discontinued in June 1995. The only other wells downgradient are seven monitoring wells (0.65 miles southeast of the site) in the North Kansas City Sludge Landfill that is adjacent to the Missouri River. The wells are used only for environmental monitoring. All seven wells had arsenic concentrations in August and November 1996 sampling events, with levels ranging from 0.050 to 0.171 ppm (1).

On May 22-24, 1996, the Environmental Protection Agency (EPA) performed a Time Critical Removal Action to reduce the exposure hazards at the site. On the south and west of the building, contaminated soil with over 200 ppm arsenic was covered with polypropylene geo-fabric and crushed rock. The rest of the site is covered with concrete or the building. Also, a temporary six-foot chain-length security fence was placed at the southern and eastern borders of the site to complete the fence around the site (1).

On July 26, 1996, a site visit was conducted by DOH and Missouri Department of Natural Resources (MDNR) personnel to observe the site conditions and determine if exposure was occurring since the Time Critical Removal Action. No sign of trespass was observed. The cover over the contaminated soil was in good, but deteriorating condition. It was able to prevent direct exposure to contaminated soil as well as inhalation exposure from possible dust being generated from the site. A problem was noted during the site visit in that access could be gained through an incomplete fence connection in the northwest corner of the site. This is located next to some demonstration playground sets on the adjoining hardware store property. The MDNR staff person agreed to pass this information on and have it corrected. The downgradient contaminated off-site well, one quarter mile from the site, was also observed and found to be disconnected and not-in-use.

On October 21, 1997, DOH and MDNR personnel again visited the site and were given a site tour, a site history, and were updated on what activities have occurred at the site. Other personnel from United States Geological Survey and an environmental consultant for the neighboring property were also present. The previous problem with the northwest corner of the chain-link fence had been corrected and the off-site contaminated well was reported to still be disconnected. The chain-link fence around the site was still in place, but the main gate was unlocked. Also, the fence had been separated in one spot. Evidence (scratch marks on the gravel surface and footprints) was present indicating that someone may have used the gap for an entrance into the site. Deterioration of the polypropylene geo-fabric and gravel cover had occurred, allowing the contaminated soil to become exposed, especially in the drainage ditch on site. Groups of pigeons were also seen entering and leaving the building. The MDNR remedial project manager said that the lack of security would be passed on to the enforcement division to be corrected.

The 1990 population of North Kansas City is 4,130 with 95.3 % of the residents being white, 1.7 % black, and 3 % of other races. Children six years old and younger account for 6.7 % of the population and those 65 years and older account for 23.7 % of population. In 1989, approximately 12 % of the residents were considered to be below the poverty level (6). An estimated 3,798 persons live within one mile from the site (3).

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