PUBLIC HEALTH ASSESSMENT
MID-AMERICA TANNING COMPANY
SERGEANT BLUFF, WOODBURY COUNTY, IOWA
The Mid-America Tanning (MAT) site is an abandoned tanning facility. Located in the Port Neal Industrial District in Woodbury County, Iowa, this 98.7 acre site sits about seven miles south of Sioux City and four miles south of Sergeant Bluff. The site lies within the Missouri River Valley Region. The region is extensively farmed for grain crops such as corn and soybeans.
MAT operated as a hide processing plant from 1969 to 1989. To tan the hides, the plant used a chrome processing procedure (1). Sludge was generated as a by-product of the tanning process. The sludge accumulated in two aeration basins and a large polishing basin west of the tanning building. In 1979, approximately 900 cubic yards of sludge were disposed of in an unlined trench on the property.
The site was identified as a potential problem in 1980 by the Iowa Department of Natural Resources (IDNR) because of the disposal of filter-pressed sludge in an unlined trench on-site. Prior to 1979, the filter-pressed sludge had been disposed of at the Woodbury and Sioux City Sanitary Landfill. The U. S. Environmental Protection Agency (EPA) conducted a Preliminary Assessment/Site Investigation (PA/SI) in 1985. Sediment chromium concentrations within the disposal trench and from an Oxbow Lake on-site were 47,000 milligrams per kilogram (mg/kg) of sediment and 5,400 mg/kg, respectively. Chromium was detected in two on-site monitoring wells above the Maximum Contaminant Level (MCL) for total chromium, which was then set at 50 micrograms per liter (g/L) of water. Total metal concentrations of arsenic, barium, chromium, iron, lead, and manganese were detected in on-site surface soil and groundwater above background levels. The site was listed by the EPA on the National Priorities List (NPL) in 1989 (2).
In June 1990, the Iowa Department of Public Health (IDPH), under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR), issued a Preliminary Health Assessment (PHA) for the site. IDPH concluded, based on review of the PA/SI, that the site was a potential public health concern. A risk to human health existed because of the likelihood of exposure to hazardous substances via groundwater, surface water, and soil. The PHA recommended that further environmental characterization and sampling of the site (as well as impacted off-site areas) be conducted during the Remedial Investigation and Feasibility Study (RI/FS) (1).
EPA began removal assessment and RI/FS activities in July 1990. Eighteen monitoring wells were installed in the alluvial aquifer to determine the extent of groundwater contamination. Site assessment was performed to define the extent of metal contamination in lagoon sludge, and to establish whether heavy metals were migrating from the two aeration lagoons. An inventory of all chemicals remaining at the site was also conducted. During the RI/FS, EPA was informed that, in 1988, two employees who were working in a manhole associated with the waste treatment system died as a result of hydrogen sulfide exposure (2).
EPA's Emergency Planning and Response Branch, conducted a Removal Action at the site in 1991 (3). The volume of surface soil containing chromium was estimated to be 12,000 cubic yards. Characterization of sub-surface soil in the former disposal trench for the presence of arsenic, cadmium, barium, chromium, and lead was also performed. The removal included the excavation, stockpiling, and containment of approximately 1,300 tons of buried sludge, containment of primary clarifier sludge, containment of discarded acids and tanning solutions, and a cursory cleaning of the hide-processing building interior.
In 1995, a follow-up Removal Action was conducted. This included removal of drums and debris, cleaning out and sealing off buildings, and welding manhole covers closed. Entrance to the site was restricted by a chain-link fence approximately 10-feet high. Signs were posted at the entrance and other places on-site to inform the public about the restricted area.
The 1990 PHA concluded that further environmental characterization and sampling of the site was necessary because of the potential risk to human health from exposure to hazardous substances via groundwater, surface water, and soil. Since that time, extensive characterization and sampling have occurred at the site. Removal actions at the site have abated the potential risks of exposure to site contaminants and associated physical hazards. Contaminated source areas have been remediated.
The groundwater contamination has been monitored since 1985 and a subsequent assessment was completed in 1997. It was concluded that there is no risk to human health and the environment from the groundwater, and the remaining contaminants will not adversely impact groundwater quality.
The MAT site does not pose a public health risk. Previous removal and remedial actions taken at the site and the lack of groundwater contamination eliminate the need for further action.
A. Site Description and History
Mid-America Tanning (MAT) encompasses 98.7 acres of the northeast quarter of Section 19 of Woodbury County in northwestern Iowa. It is located approximately 7 miles south of Sioux City, Iowa, and 4 miles southwest of Sergeant Bluff, Iowa (Figures 1 & 2). The site is situated in an industrial area known as the Port Neal Industrial District 1.5 miles west of U.S. Interstate Highway 29 and approximately 1.5 miles northeast of the Missouri River.
In December 1968, Needham Packing Company acquired the site, and ownership of the site was then transferred to the municipality of Sioux City, Iowa. At that time the site was leased back to Needham Packing Company. Hide processing operations began in the first quarter of 1970. Operations at the facility included fleshing, curing, and trimming of hides until about 1973. Very little chrome tanning of hides occurred until Needham Packing Company changed its name to Flavorland Industries in 1973. At that point in time, Flavorland Industries increased its chrome tanning operations, and by 1976, chrome tanning operations accounted for approximately 40 percent of facility operations.
Ownership of Flavorland Industries changed in 1974. In December 1976, labor disputes coincided with the closing of the plant. In April 1978, the municipality of Sioux City transferred ownership back to Flavorland Industries. Flavorland Industries immediately sold the property to MAT. MAT used a "through the blue" tanning process or chrome tanning as the predominant plant operation (1). In May 1985, Mid-America Tanning filed for bankruptcy, and in November 1985 the company changed its name to U.S. Tanning Company, Inc. U.S. Tanning Company continued the "through the blue" tanning process until approximately November 1989, at which time all hide processing operations and other business activities ceased.
In 1979, approximately 900 cubic yards of sludge were disposed of in an unlined trench on the property. The U. S. Environmental Protection Agency (EPA) conducted a Preliminary Assessment/Site Investigation (PA/SI) in 1985. Sediment chromium concentrations within the disposal trench and from an Oxbow Lake on-site were 47,000 milligrams per kilogram (mg/kg) of sediment and 5,400 mg/kg, respectively. Chromium was detected in two on-site monitoring wells above the Maximum Contaminant Level (MCL) for total chromium, which was then set at 50 micrograms per liter (g/L) of water. Total metal concentrations of arsenic, barium, chromium, iron, lead, and manganese were detected in on-site surface and groundwater above background levels.
In March 1986, the U.S. Environmental Protection Agency (EPA) conducted a follow-up site investigation (SI) to determine if there had been a release of contaminants from MAT's waste disposal trenches into the groundwater. The SI included a geophysical survey, the installation of five on-site monitoring wells, collection of seven on-site groundwater samples, and two off-site groundwater samples to represent background conditions. Results of the SI indicated groundwater underneath the site contained arsenic, barium, chromium, lead, and manganese above background levels. In February 1987, EPA sampled four of the five on-site monitoring wells and two off-site background wells. Elevated levels of arsenic, barium, cadmium, chromium, and lead were detected in the on-site wells. These levels had generally increased since 1986. Because of the new data, EPA placed the site on the National Priorities List (NPL) in June 1988. EPA and contractors for U.S. Tanning again sampled groundwater in August 1989. Data again revealed elevated levels of arsenic, barium, cadmium, chromium, and lead.
MAT was finalized for inclusion on the NPL in March 1989 (2). On December 2, 1989, an Administrative Order to U.S. Tanning was issued to direct them to perform removal actions and a Remedial Investigation/Feasibility Study (RI/FS) at the MAT site. U.S. Tanning failed to comply with the order as all business ceased at the facility in November 1989. In September 1991, a Record of Decision (ROD) was signed. Concurrent investigations into MAT operations informed EPA that two personnel deaths occurred when the plant was operational in 1988. The plant personnel died from being exposed to hydrogen sulfide gas after entering a manhole associated with the wastewater treatment system. This information warranted air monitoring for acute levels of toxic gases and further investigations to confirm their continued presence.
From July-August 1990, a Remedial Investigation (RI) was conducted by the Technical Assistance Team (TAT) from E&E/FIT at the MAT site. Media investigated for contamination at the site included surface waters and sediments in Oxbow Lake, which crosses the site; surface and subsurface soils in a sludge disposal trench area; liquids and sludge in the east and west aeration lagoons, polishing basin, primary and final clarifiers, and concrete aeration basin; and groundwater. Eighteen monitoring wells were installed in the alluvial aquifer to determine the extent of groundwater contamination. From May-December 1990, TAT also conducted a site assessment to define the extent of metal contamination in the lagoon sludge, establish whether heavy metals were migrating from the two aeration lagoons, and compile an inventory of all chemicals remaining on site.
During the spring of 1991, EPA re-sampled the groundwater monitoring wells at the site to eliminate data gaps and to update arsenic and lead sampling data previously collected at the site.
The characterization of contaminated surficial soils containing chromium wastes was completed by March 1991 (Figure 6). Other activities included the characterization of subsurface soils in the former burial area for the presence of arsenic, cadmium, barium, chromium, and lead.
B. Actions Implemented During the Public Health Assessment Process
EPA's Emergency Planning and Response Branch conducted a Removal Action at the site in 1991. The Removal Action included the excavation, stockpiling, and containment of buried sludge; containment of primary clarifier sludge, discarded acids, and tanning solutions; and cursory cleaning of the interior of the hide processing building.
The volume of surface soil containing chromium was estimated to be 12,000 cubic yards. It was estimated that approximately 1,290 tons of subsurface soils containing total chromium concentrations above 2,000 parts per million (ppm) were excavated from the sludge disposal trench and stockpiled on-site on a 40 millimeter polyvinyl chloride synthetic liner. Dust and debris on the floors of the hide processing and filter press building were also swept up and stockpiled with the excavated material from the sludge disposal trench. Sludge from the aeration lagoons and tank were also characterized. Approximately 15 cubic yards of sludge from the primary clarifier was removed and stockpiled on-site. The liquid portion had been removed from the primary clarifier and transferred to the east aeration lagoon.
Approximately 5,000 gallons of chromium sulfate solution were treated with calcium hydroxide and left to precipitate the chromium out of solution. The chromium precipitate, considered to be a hazardous waste, was stored in a tank in the hide processing building. Another tank containing approximately 300-500 gallons of sulfuric acid was also found on the roof of the main facility building. It was left in place for eventual disposal with the chromium tank and excavated material.
On September 24, 1991, EPA signed the Record of Decision (ROD)for the MAT site. The remedial actions selected included in-situ immobilization of densely-contaminated sediments in the east and west aeration lagoons and the northeast field, and the placement of soil-clay caps over the less densely-contaminated source areas. Water in site-impoundments was treated in compliance with National Pollution Discharge Elimination System (NPDES) permit criteria. After water was removed from the impoundment areas, the areas were immobilized in-situ with an auger system that mixes a solidifying agent and additive directly into the contaminant matrix, thereby solidifying and stabilizing the matrix.
The impoundments were backfilled, capped with clay soil, and graded to reduce water accumulation. A soil-clay cap was also placed over the polishing basin. Top soil was added to the immobilized areas and seeded to control erosion.
In 1995, a follow-up Removal Action was conducted. This included removal of drums and debris, cleaning out and sealing off buildings, and welding manhole covers closed. Entrance to the site was restricted by a chain-link fence approximately 10-feet high. Signs were posted at the entrance and other places on-site to inform the public about the restricted area.
Thus, removal actions at the site have abated the potential risks of exposure to site contaminants and associated physical hazards. Contaminated source areas have been remediated.
The groundwater contamination was monitored from 1985 to 1997. It was concluded that there is no risk to human health and the environment from the groundwater, and the remaining contaminants will not adversely impact groundwater quality.
On March 17, 1993, Iowa Department of Public Health (IDPH) staff visited the MAT site. Areas of special interest were the soil stockpile area and the location of the previous burial trench, concrete aeration basin, east and west aeration lagoons, the polishing basin, site buildings, and other structures. The on-site and off-site Oxbow Lake, on-site and off-site monitoring wells, off-site private wells, and the surrounding land and building structures within one-half mile of the site boundary were located. Access to the on-site area was not fully restricted. The entrance to the MAT site was restricted by a chain-link fence approximately 10 feet high; however, the fence only restricted vehicles from driving onto the property and did not restrict trespassers from entering by foot. Signs were posted at the entrance and a few places on site to inform the public about the restricted area. During the site visit, it was evident that trespassers had entered the property and had hunted near physical hazards. Evidence indicated that children lived on farms where some of the off-site wells were located. The site was obviously attractive to duck hunters; spent shot-gun shell casings were found near the east and west lagoons, the polishing basin, and the on-site Oxbow Lake area.
On June 16, 1996, IDPH and IDNR staff revisited the site. Entrance to the site was restricted by a chain-linked fence approximately 10-feet high. Signs were posted at the entrance and other places on-site to inform the public about the restricted area. The site was well vegetated. Previous Removal Actions had included removal of drums and debris, cleaning out and sealing off buildings, and welding manhole covers closed. By this time, potential risks of exposure to site contaminants and associated physical hazards had been removed.
At the time this document was being prepared, no changes in access to the site or in the site's physical conditions were noticed since the previous site visit.
D. Demographics, Land Use, and Natural Resource Use
Demographics
The MAT site is located in Woodbury County, Iowa. Municipalities located close to the site are the towns of Sergeant Bluff, Iowa, approximately 4 miles northeast of the site, and Salix, Iowa, approximately 4 miles southeast of the site. According to the 1990 census, the city of Salix has a population of approximately 367 people, and the city of Sergeant Bluff has approximately 2,772 people. For both towns, approximately 35% of the population are below the age of 18 years; while approximately 10% are 65 years of age or older. Also, for both towns, approximately 97% of the population is White with the other 3% of the population divided equally among Asians, Blacks, and Hispanics.
Land Use
The immediate area surrounding the MAT site is used for industrial and agricultural purposes. The site is situated within the Port Neal Industrial District.
Natural Resource Use
Farmland and wildlife habitat also surround the area. The Port Neal Industrial District is located within the Missouri River Valley, which is extensively farmed for grain crops such as corn and soybeans. Pastureland comprises the rest of the agricultural land uses. Local ecology around the site is associated with wetland areas such as Oxbow Lake and woody thickets or woodland areas. Two recreational areas within a five mile radius of the site are Snyder Bend County Park and Browns Lake State Park. Both of these areas are located south-southeast of the site (Figure 4).
Using state health databases, special studies, or other relevant health outcome databases, it may be possible to determine whether certain health effects are higher than expected in areas surrounding hazardous waste sites. This section introduces the databases available.
IDPH maintains the vital statistics (birth, death, and fetal death reports). The University of Iowa maintains the cancer and birth defects registries. The state cancer registry has collected data since 1969. The birth defects registry has collected data since 1985.
Although information derived from the state cancer and birth defects registries may make it possible to determine if health effects are related to exposure from site contaminants, people have not been exposed to the contaminants of concern at this site. Therefore, no adverse health outcomes would be expected. Also, area residents have not mentioned any specific health concerns related to the site. For these reasons, health outcome data has not been evaluated for this site.
EPA and representatives of Iowa Department of Natural Resources (IDNR) conducted a public meeting in Sergeant Bluff on June 28, 1990. At this meeting, representatives from EPA, IDNR, and IDPH presented information and answered questions about the site and the remedial alternatives under consideration. Residents interviewed by IDPH staff said they did not know of anyone who has experienced health problems associated with the site. However, the residents did want to be notified if any health risks were identified during future site investigations. There were no specific health concerns voiced by the community during the public meeting.
During the public comment period from July 1, 1994 through August 1, 1994, the following two public health concerns were received about the site:
ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS
Tables in this section list contaminants of concern at the MAT site that were identified during the RI/FS process. However, their listing does not imply that a health threat exists. An evaluation of contaminants in subsequent sections determines whether exposure has occurred and if such exposure has public health significance. IDPH and ATSDR select the contaminants of concern based on the following factors: (1) concentrations of contaminants on and off the site, (2) field data quality, laboratory data quality, and sample design, (3) comparison of site-related concentrations with background concentrations, (4) comparison of site-related concentrations with health assessment comparison values for noncarcinogenic and carcinogenic endpoints and other appropriate values, and (5) community health concerns. A contaminant that is listed does not imply that adverse health effects will result from exposure, but indicates that a contaminant must be further evaluated in the public health assessment process.
Contaminants requiring further evaluation are selected by using medium-specific comparison values. These values include Environmental Media Evaluation Guides (EMEGs), Reference Dose Media Evaluation Guides (RMEGs), Cancer Risk Evaluation Guides (CREGs), and other relevant environmental guidelines.
EMEGs are estimated contaminant concentrations in the environment at which daily exposure would be unlikely to result in non-cancerous health effects. EMEGs are calculated from ATSDR Minimal Risk Levels (MRLs). MRLs are estimates of daily exposure to contaminants below which non-cancerous, adverse health effects are unlikely to occur. If no MRLs exist for a contaminant, a comparison value, Reference Dose Environmental Media Guide (RMEG), is calculated from an EPA Reference Dose (RfD). A RfD is an estimate of the daily exposure to a contaminant that is unlikely to result in non-cancerous, adverse health effects. CREGs are estimated contaminant concentrations in the environment that are based on the Cancer Slope Factor. The Cancer Slope Factor is the estimated probability that, in one million people exposed, one excess cancer (one cancer above the expected background number) will result because of a lifetime of exposure to the contaminant. EPA Maximum Contaminant Levels (MCLs) represent contaminant concentrations in public drinking water supplies that EPA deems protective of public health; however, in deriving MCLs, EPA must take into consideration the technical feasibility and economics of water treatment. MCLs are regulatory concentrations.
The nature of surface soil, subsurface soil, surface water, and groundwater contamination resulting from sludge disposal and wastewater treatment facility releases to soils is discussed in the following sections. Analytical results of polishing basin sludge gases, sludge and liquids, and aeration lagoon sludge gases and liquids are also discussed.
A large amount of soil had been stockpiled at the site. That soil contained chromium, which was not speciated, but was assumed to contain approximately 0.1% hexavalent chromium. This percentage was determined during the Remedial Investigation (1).
Although the presence of chromium at the site prompted historic concern and actions, the levels of chromium, assuming 0.1% hexavalent chromium, do not exceed ATSDR comparison values. Therefore, chromium will not be further evaluated in this document.
During the July and August 1985 Site Investigation (SI), four surface soil samples were collected from a cornfield (field #1) where sludge was incorporated into the soil. The cornfield is directly north of the hide processing building. The results of surface soil samples taken during the SI, indicate that arsenic and manganese are present at levels above comparison values (Table 1). In 1990, during the RI, surficial soil in the disposal and suspected surficial contamination areas were measured for various metals. The sampling strategy involved collecting samples from a grid pattern. Samples were collected from areas known to have received chromium-contaminated waste (Figure 6). Three composite samples of surficial soil were collected from each sample section. Arsenic was found at its highest level on the southwest corner of the site. However, arsenic levels are comparable to background levels.
TABLE I. ON-SITE SURFACE SOIL (mg/kg)
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(1985)-SI |
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| Arsenic |
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|
| Manganese |
|
|
|
| (1990)-RI | |||
| Arsenic |
|
|
|
mg/kg-Milligrams per kilogram.
CREG--Cancer Risk Evaluation Guide.
RMEG--Reference Dose Media Evaluation Guide.
SI--Data from the Site Investigation
RI--Data from the Remedial Investigation
Nine subsurface soil samples were collected at four different boring locations (B1-B4) during the 1985 SI. Samples from borings B1 and B2 were collected at 11 feet, 16 feet, and 21 feet. Samples from borings B3 and B4 were collected at 11 feet and 16 feet. Subsurface soil results revealed heavy metal contamination at several locations.
The 1990 RI included sampling analyses for arsenic, barium, cadmium, total chromium, lead, volatile, and semi-volatile priority pollutants. Samples of subsurface soil were obtained during the installation of shallow and intermediate well borings. The vertical extent of contamination was not clearly defined in subsurface soils because there was no consistent trend of individual contaminants by depth. Metal concentrations were generally the highest in the upper 8.5 feet of soil across the site. In general, concentrations were not significantly higher than background or off-site levels. Analytical sampling results of the SI and RI are shown in Table II. The tables list maximum concentrations of contaminants found above comparison values.
TABLE II. ON-SITE SUBSURFACE SOIL (mg/kg)
|
(1985-1990) |
SI/RI |
SI/RI* |
|
| Arsenic |
|
|
|
| Manganese |
|
|
|
| Beryllium |
|
|
|
mg/kg-Milligrams per kilogram.
CREG--Cancer Risk Evaluation Guide.
RMEG--Reference Dose Media Evaluation Guide.
*Data are from the Site Investigation (SI) and the Remedial Investigation (RI)
Surface water drainage at the MAT site primarily comes from the primary and final clarifiers, east and west earthen aeration lagoons, and the polishing basin. The water eventually drains into the on-site Oxbow Lake and subsequently flows off-site. Surface water from the north and from the Kind and Knox (K&K) facility to the north also flows southward into Oxbow Lake. This drainage could influence contaminant concentrations in, and south of, Oxbow Lake.
Surface water samples were collected from MAT's Oxbow Lake at a point directly north of the primary clarifier (AAJ03019), near the north end of the drainage ditch (Figure 4). Background surface water samples were also collected from Browns Lake. Surface water in Oxbow Lake contained levels of arsenic, barium, cadmium, manganese, and vanadium at concentrations above comparison values (Table III). Lead, mercury, nickel, and zinc were not at levels above comparison values, but are included in the table to illustrate comparisons between surface water and groundwater data, as well as on-site and off-site values.
Between May and June 1990 (during the RI), surface water was again sampled from Oxbow Lake. The water had a pH of 7.15-8.03, and metals were found to be oxidizing. At that time, only manganese was detected above comparison values. Barium was not detected above comparison values, but was included in the table in order to compare the 1985 and 1990 data, surface water and groundwater values, and the on-site and off-site values.
TABLE III. ON-SITE SURFACE WATER (g/L)
|
(1985)-SI |
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|
|
| Arsenic |
|
|
|
| Barium |
|
|
|
| Cadmium |
|
|
|
| Lead |
|
|
|
| Manganese |
|
|
|
| Mercury |
|
|
|
| Nickel |
|
|
|
| Vanadium |
|
|
|
| Zinc |
|
|
|
| (1990)-RI | |||
| Barium |
|
|
|
| Manganese |
|
|
|
g/L-Micrograms per Liter
CREG-Cancer Risk Evaluation Guide
EMEG-Environmental Media Evaluation Guide
RMEG-Reference Dose Media Evaluation Guide
MCL--EPA Maximum Contaminant Level
LTHA-Lifetime Health Advisory
SI-Data from the Site Investigation
RI-Data from the Remedial Investigation
Groundwater in the alluvial aquifer is theorized to be moving westward beneath the MAT site (Figure 12). Area groundwater is affected by several sources in the area of the site. Runoff and shallow groundwater flow in the southern area of the K&K company could contribute to contamination of the polishing basin and Oxbow Lake. Seepages from the polishing basin, Oxbow Lake, and the aeration lagoons could contribute to groundwater contamination.
During the preliminary SI in 1985, groundwater samples were collected from borings B-1 and B-2 (see Table IV), but because of the lack of borehole integrity, the samples were not considered a good representation of groundwater quality. When elevated metal concentrations were detected in groundwater, a recommendation was made to further characterize the extent of groundwater contamination.
During the 1986 SI, EPA installed five monitoring wells in the alluvial aquifer and collected nine groundwater samples (including one on-site drinking water well and two off-site background samples). Two residential wells approximately 2 miles north of the site were used as background samples. A geophysical and magnetometer survey of the site was also conducted at that time. The surveys were conducted in order to determine the best locations for five monitoring wells. An electromagnetic (EM) conductivity meter was used to survey a suspected sludge disposal area. While drilling monitoring well MW-1, a dark gray fibrous sludge was encountered from six to thirteen feet below the surface. The material was not encountered in any of the other monitoring well installations.
Groundwater samples were analyzed for total and dissolved metals. Groundwater from the site contained arsenic, lead, manganese, chromium, and vanadium. However, only arsenic and lead were considered to be above background levels, while arsenic, lead, manganese, and vanadium were above comparison values. The 1986 levels for contaminants listed in Table IV are for total metals. Dissolved metal analyses also showed arsenic and manganese present in MW-1 at 18 micrograms per liter (g/L) and 680 g/L, respectively.
In August 1989, MW-1 was again sampled by contractors for U.S. Tanning. Split samples were collected, and analyses for total and dissolved metals were conducted. Contaminants present at levels above comparison values were arsenic at 40 g/L dissolved(d) and 48 g/L total(t), barium at 878 g/L d and 1,150 g/L t, and cadmium at 7 g/L d and 14 g/L t. No other data from this sampling event is available.
For the RI (1990-1991), 18 additional wells were installed in the alluvial aquifer near the MAT disposal areas and Oxbow Lake to assess the nature and extent of groundwater contamination in the alluvial aquifer. Wells were originally identified according to depth as shallow (S), intermediate (I), and deep (D). S, I, and D wells are 48-50 feet, 70 feet, and 100-110 feet from the soil surface, respectively. Contaminants of concern for the 1990 sampling event are listed in Table IV. Arsenic, chloride, fluoride, and zinc were the only contaminants detected above background levels. Arsenic and zinc levels were only slightly above background levels.
Additional groundwater samples were collected by EPA in April 1991 to complete data gaps created by unusable data. The 18 wells originally installed during the RI were re-sampled and analyzed for total metals (Table IV). Contaminants of concern detected in the 1991 sampling event were arsenic, barium, beryllium, cadmium, lead, manganese, nickel, and vanadium. However, barium, beryllium, and cadmium were at background levels. The heavy metals arsenic, manganese, and nickel were detected at levels at least 2-5 times higher than background levels.
TABLE IV. ON-SITE GROUNDWATER (g/L)
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Value |
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| Arsenic |
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|
|
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| Barium |
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||
| Cadmium |
|
|
|
||
| Lead |
|
|
|
|
|
| Manganese |
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|
|
|
|
| Mercury |
|
|
|
||
| Nickel |
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|
|
||
| Vanadium |
|
|
|
|
|
| Zinc |
|
|
|
||
| (Year) |
|
|
|
|
|
| Arsenic |
|
|
|
|
|
| Barium |
|
|
|
|
|
| Manganese |
|
|
|
|
|
| Beryllium |
|
|
|
|
|
| Cadmium |
|
|
|
|
|
| Chloride |
|
|
|
||
| Fluoride |
|
|
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||
| Lead |
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|
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||
| Nickel |
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||
| Vanadium |
|
|
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||
| Zinc |
|
|
|
||
g/L-Micrograms per Liter
J - Estimated Value
CREG - Cancer Risk Evaluation Guide
EMEG - Environmental Media Evaluation Guide
LTHA - Long Term Health Advisory
RI - Data from Remedial Investigation
* - Filtered
MW - Monitoring well
RMEG - Reference Dose Media Evaluation Guide
MCL - EPA Maximum Contaminant Level
SI - Data from Site Investigation
Polishing basin sludge and liquids
Investigations associated with the polishing basin were conducted to acquire data to assess potential contaminant migration, evaluate potential environmental risks, and evaluate remedial options. The investigation focused on sampling the liquid and sediment (sludge). Sludge and liquids were sampled between May and September 1990, and the samples were analyzed for major ions, total metals, volatile organic compounds, and semi-volatile organic compounds. The basin was divided into eleven one-acre sections to characterize the spacial distribution of contaminants. Composite samples of each one-acre section were analyzed. Concentration ranges for each contaminant of concern found are listed in Tables V and VI.
Sludge samples were collected from a depth of zero to six inches (zero being the liquid-sediment interface), six inches down to refusal, and at the bottom of the polishing basin. Contaminants that were found in the sludge at concentrations above comparison values were antimony, arsenic, and manganese (Table V). Liquid samples were collected in the zone of the liquid column from the surface to a depth of approximately six inches at all sampling locations. Contaminants that were found in the liquid at concentrations above comparison values were ammonia, chloride, fluoride, and manganese (Table VI).
TABLE V. MAY-SEPTEMBER 1990 POLISHING BASIN SLUDGE (mg/kg)
|
|
|
|
| Antimony |
|
|
| Arsenic |
|
0.4 CREG
|
| Manganese |
|
|
mg/kg - milligrams per kilogram
RMEG - Reference Dose Media Evaluation Guide
CREG - Cancer Risk Evaluation Guide
Data from the Remedial Investigation
TABLE VI. MAY-SEPT 1990 POLISHING BASIN LIQUIDS (g/L)
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|
|
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| Ammonia |
|
|
| Chloride |
|
|
| Fluoride |
14,400-24,900
|
|
| Manganese |
|
|
g/L - Micrograms per Liter
MCL - EPA Maximum Contaminant Level
RMEG - Reference Dose Media Evaluation Guide
NA - medium guide not available
Data from the Remedial Investigation
The east and west aeration lagoons were sampled in September 1990 to characterize the liquid nature of contamination in the lagoons. A limited data base of sampling information was available because only one liquid sample was obtained from each lagoon. Each sample was used to evaluate if the aeration lagoons were a potential source for groundwater and surface water contamination. The sample from the east lagoon was collected from the center of the east bank, and the sample from the west lagoon was collected from a wooden pier leading to an outlet structure. Liquid in the east lagoon ranged from approximately 4-7.5 feet in depth, while liquid in the west lagoon was approximately 1.5 feet deep. Contaminants of concern were total and dissolved chromium, ammonia, chloride, and fluoride (Table VII).
TABLE VII. MAY-SEPTEMBER 1990 AERATION LAGOON LIQUIDS (g/L)
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Contaminant |
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|
|
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| Ammonia |
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g/L - Micrograms per Liter
MCL - EPA Maximum Contaminant Level
RMEG - Reference Dose Media Evaluation Guide
NA - medium guide not available
Data from the Remedial Investigation
Aeration lagoon sediments were sampled during the RI; however, no contaminants exceeded comparison values.
Polishing basin/aeration lagoon sludge off-gas air
monitoring
Air monitoring and air sampling for the presence of hydrogen cyanide and hydrogen sulfide was performed on sediment samples collected from the east and west aeration lagoons and the polishing basin. Impoundmentoff-gas was sampled in an enclosed space by dragging a five-gallon bucket attached to a rope through sludge surfaces and air sampling the head space within the bucket. IDNR had some questions regarding the validity of this technique.This method allowed only the upper one foot of each impoundment to be sampled. Air samples for hydrogen sulfide and cyanide gas were deleted from the sampling agenda because of the inaccuracy associated with the sampling method. Air sampling for hydrogen cyanide was determined to be compromised by levels of hydrogen sulfide in the sludge. Later, analytical results and air monitoring data indicated that hydrogen cyanide was not present in the sludge off-gases. However, hydrogen sulfide was detected in sludge off-gases. Air monitoring results are summarized in Table VIII. The comparison value for hydrogen sulfide levels in air is the EPA Reference Concentration of 0.9 micrograms per cubic meter (g/m3) or 0.0009 milligrams per cubic meter (mg/m3).
TABLE VIII. Hydrogen Sulfide Air Monitoring of Sludge off-gas, per IDNR 08/03/94 (mg/m3)
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mg/m3 - milligrams per cubic meter
Data from the Field Sampling Trip Report (11/92)
The contamination measured off-site was performed primarily to determine the extent of contamination from possible on-site sources and to determine the degree of background levels of the elements in the surrounding environment. Although some elements were measured at levels above comparison values, most levels of elements found are considered to be within naturally occurring levels for the environmental media sampled. Because of safety factors calculated into comparison values, a number of the comparison values are lower than levels of elements found naturally in soils and water.
Background surface and subsurface soil samples were taken during the SI and RI between 1985 and 1990. Contaminants that exceeded comparison values in surface and subsurface soils are listed in Table IX. Arsenic and manganese were both detected at levels above comparison values in surface soils off-site near Browns Lake. They were also found at levels above comparison values in subsurface soils during the drilling of off-site monitoring wells 1S and 3S. Beryllium was detected at a level above comparison values during the drilling of 3S. However, all concentrations detected in the surface and subsurface soil locations off-site fall within naturally occurring concentration ranges.
TABLE IX. OFF-SITE SURFACE AND SUBSURFACE SOIL (mg/kg)
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Surface
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| Arsenic | Browns Lake |
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| Manganese | Browns Lake |
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mg/kg - Milligrams per kilogram
CREG - Cancer Risk Evaluation Guide
RMEG - Reference Media Evaluation Guide
Data from the Site Investigation and Remedial Investigation
Contaminants in off-site surface water and groundwater were detected at levels exceeding comparison values during the 1985-1991 sampling period (Table X). However, the levels detected were considered to be within background ranges. Arsenic, cadmium, and vanadium were detected in surface water in Browns Lake, while barium and manganese were detected at their highest value approximately ½ mile from Oxbow Lake. Arsenic, barium, beryllium, cadmium, chloride, fluoride, nickel, vanadium, and zinc were all detected at levels above comparison values in off-site monitoring wells near the site. However, all the monitoring wells except the Terrachem company well are considered up-gradient from the alluvial groundwater flow direction at the site. The Terrachem well is also a much deeper well and taps the granite aquifer southwest of the site. The levels of metals detected in that well, including the 10,000 g/L of manganese, were within established background levels for that aquifer. Wells 903S and 3S are up-gradient of the site, but down-gradient from the K&K company. No metals were detected in those wells above background concentrations.
TABLE X. OFF-SITE SURFACE WATER AND GROUNDWATER (g/L)
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(1985-1991) |
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Concentration |
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| Arsenic | Browns Lake |
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| Beryllium |
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| Barium | ½ mi. North of site on Oxbow Lake |
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| Cadmium | Browns Lake |
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| Chloride |
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| Fluoride |
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| Manganese | ½ mi. South of site on Oxbow Lake |
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| Nickel |
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| Vanadium | Browns Lake |
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g/L - Micrograms per Liter
NA - Not Applicable
MCL - EPA Maximum Contaminant Level
CREG - Cancer Risk Evaluation Guide
EMEG - Environmental Media Evaluation Guide
LTHA - Lifetime Health Advisory
RMEG - Reference Media Evaluation Guide
Data from the Remedial Investigation and Site Inspection
C. Toxic Chemical Release Inventory Information
To identify companies that could contribute to surface and groundwater contamination in proximity of the MAT site, IDPH searched the Toxic Chemical Release Inventory (TRI) Database from 1987-1990. The TRI is developed by EPA from data submitted on estimated annual releases (emission rates) of toxic chemicals to the environment (air, water, land, or underground injection) by industries with 10 or more full-time employees, in accordance with federal law. The TRI did contain information on an industry that could be influencing this site. The Kind & Knox Gelatin, Inc., (K&K company) has released chlorine, hydrochloric acid (HCL), phosphoric acid, sodium hydroxide (NaOH), sulfuric acid (H2SO4), and ammonia into their wastewater treatment system. This wastewater eventually drains into Oxbow Lake north of the site. The drainage then flows into the MAT site and eventually to the Missouri River. Surface water possibly leaches into the alluvial aquifer and influences groundwater contamination at the MAT site because the MAT site is located hydrologically down-gradient of the K&K company.
D. Quality Assurance and Quality Control
Quality Assurance/Quality Control (QA/QC) information on the field and laboratory data was obtained for this public health assessment. Field blanks, trip blanks, duplicate samples, and/or split samples were analyzed.
In preparing this public health assessment, IDPH relied on the information provided in the referenced documents and assumes that adequate QA/QC measures were followed with regard to chain of custody, laboratory procedures, and data reporting. The validity of the analyses and conclusions drawn in this public health assessment were determined by the availability and reliability of the referenced information.
Furthermore, during the preparation of this public health assessment, IDPH concluded that the data was adequate and reliable.
No physical or other hazards currently exist at the site.
The environmental and human components that lead to possible human exposure are evaluated and presented in this section of the public health assessment. IDPH and ATSDR determine whether people have been exposed to contaminants from the site in the past, are being exposed now, and whether they could be exposed to contaminants in the future. A completed exposure pathway consists of the following elements: a source of contamination, transportation of the contaminant through an environmental medium, a point of exposure, a route of human exposure, and an exposed population. An exposure pathway can be complete or potential. In a completed exposure pathway, all the above elements exist and indicate that exposure to a contaminant has occurred in the past, may be occurring now, or will occur in the future. In a potential pathway, at least one of the above elements is missing, although risk of exposure may still exist. Potential pathways indicate that exposure from a contaminant may have occurred in the past, may be occurring, or may occur in the future. An exposure pathway can be eliminated if one or more elements is missing and is likely never to exist.
A. Completed Exposure Pathways
No completed exposure pathways have been identified at the site.
B. Potential Exposure Pathways
Contaminated soils have been removed from the site. Thus, there is no longer a source for exposure. However, past exposure to contaminated soil could have occurred with remedial workers. Subsurface soils had contained metals at concentrations above comparison values. Unprotected remedial workers could have came into contact with the metals in the subsurface soils while excavating areas of contamination. The workers could have inhaled and ingested fugitive dust and could have came into direct contact with the metals. If surface soils contained the same levels of metals, then trespassers, as well as workers, could have came into contact with the metals through inhalation and ingestion of the soil as well as through direct skin contact.
Contaminated surface water has been removed from the site. Thus, there is no longer a source for exposure. However, past exposure to contaminated surface water could have occurred. Some metals were present in surface water on the site at concentrations above comparison values. Trespassers or workers could have fallen into the water and ingested small amounts of the water and could have came into direct contact with the metals.
On-site groundwater contains metals at concentrations above comparison values. However, exposure is unlikely to have occurred since no drinking water wells were tapped into the contaminated aquifers. Furthermore, exposure to groundwater contaminants is unlikely to occur as long as drinking water wells are not tapped into contaminated aquifers.
In this section, we will discuss the health effects that may occur in persons exposed to specific contaminants, evaluate state and local databases, and address specific community health concerns. People can only be exposed to a site contaminant if they come in contact with it. People can be exposed by breathing, eating, or drinking the contaminant or by contact with contaminated water or soil. To understand the health effects that might be caused by a specific chemical, it is helpful to review factors related to how the human body processes such a chemical. Those factors include the exposure concentration (how much), the duration of exposure (how long), the route of exposure (routes of entry; i.e., breathing, ingestion, or skin absorption), and the multiplicity of exposure (contaminant mixtures). Once exposure occurs, a person's individual characteristics such as age, sex, diet, weight, general health, lifestyle, and genetic makeup influence how the body absorbs, distributes, metabolizes, and excretes the chemical. Together, those factors determine possible health effects that exposed individuals might experience. No completed exposure pathways to contaminants have been identified at this site. Therefore, no illnesses are expected to occur as a result of site contamination. A potential exposure pathway, however, has been identified. This exposure pathway involves the possible future use of contaminated groundwater.
Heavy metals (arsenic, barium, beryllium, cadmium, lead, manganese, nickel, and vanadium) were detected at concentrations above comparison values in on-site groundwater. Currently, no private wells tap into the contaminated aquifer. Thus, as long as this remains the case, no one should become exposed to contaminated groundwater.
Private wells are believed to tap the deeper aquifer, but are not likely to become contaminated by metals from the site. This is because the aquifers are not connected, so therefore are not at risk. Metals found in some off-site monitoring wells were above comparison values, but were within naturally occurring levels for the area. Only manganese and chlorine were present in the deeper aquifer at levels of health concern (and this appears to be due to the naturally occurring levels in the area).
Manganese is a natural component of most food and water. There is no direct evidence that manganese is beneficial or essential in humans, but ingestion of manganese compounds is known to be required for good health in animals (14). The estimated dose for a person exposed to manganese at the maximum level of 10,000 g/L found in on-site monitoring wells would exceed the RfD established by EPA (14). Ingestion of up to 5,000 g manganese each day is normal (15). The RfD is derived by incorporating uncertainty factors and may result in an estimate with uncertainty spanning an order of magnitude (15).
Ingestion of the maximum levels detected in monitoring wells slightly exceed a dose above the normal daily diet intake; the dose also exceeds the RfD. For that reason, very sensitive people may experience some adverse health effects. Some symptoms may include weakness, stiff muscles, and trembling of the hands, although other factors may play a role in these types of symptoms (15). Little evidence exists to suggest that cancer is a major concern for people exposed to manganese in the environment (15).
C. Health Outcome Data Evaluation
No completed exposure pathways have been identified. Therefore, no adverse health outcomes would be expected. Moreover, area residents have not mentioned any specific health concerns related to the site. For those reasons, no health outcome data have been evaluated for this site.
D. Community Health Concerns Evaluation
During the public comment period from July 1, 1994 through August 1, 1994, two public health concerns were received about the site. The following are the questions (concerns) received and their respective responses.
In a limited study (data not shown) hydrogen sulfide was not detected in ambient outdoor air at the site so no long-term effects are expected. Testing was performed in a sealed container on gases coming out of sludge from the polishing basin and aeration lagoon. The air in enclosed on-site spaces may be hazardous for persons entering them. Note: All manhole covers have been welded shut. In the past, two workers were killed by entering enclosed spaces on-site because they did not monitor the air for toxic gases beforehand.
Health effects for someone drinking contaminated groundwater would vary depending on the contaminants, and the concentrations they were exposed to. No completed exposure pathways for contaminated groundwater (and other media) exist. Therefore, no short- or long-term health effects from drinking contaminated water are expected.
ATSDR'S CHILD HEALTH INITIATIVE
ATSDR's Child Health Initiative recognizes that the unique vulnerabilities of infants and children demand special emphasis in communities faced with contamination of their water, soil, air, or food. Children are at greater risk than adults from certain kinds of hazardous substances emitted from waste sites and emergency events. They are more likely to be exposed because they play outdoors and they often bring food into contaminated areas. They are shorter than adults, which means they breathe dust, soil, and heavy vapors close to the ground. Children are also smaller, resulting in larger doses of chemical exposure per body weight. The developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. Most importantly, children depend completely upon adults for risk identification and management decisions, housing decisions, and access to medical care.
The available information does not indicate that children are or have been exposed to site-related contaminants. Furthermore, it is unlikely that children will be exposed in the future since remedial actions have removed contaminants. Although no health follow-up actions are indicated at this time, should additional data become available, ATSDR and IDPH will evaluate that data for any follow-up health actions that may be indicated.
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