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The Mid-America Tanning (MAT) site is an abandoned tanning facility. Located in the Port NealIndustrial District in Woodbury County, Iowa, this 98.7 acre site sits about seven miles south ofSioux City and four miles south of Sergeant Bluff. The site lies within the Missouri River ValleyRegion. 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/SiteInvestigation (PA/SI) in 1985. Sediment chromium concentrations within the disposal trench andfrom an Oxbow Lake on-site were 47,000 milligrams per kilogram (mg/kg) of sediment and 5,400mg/kg, respectively. Chromium was detected in two on-site monitoring wells above the MaximumContaminant 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 weredetected in on-site surface soil and groundwater above background levels. The site was listed by theEPA on the National Priorities List (NPL) in 1989 (2).

In June 1990, the Iowa Department of Public Health (IDPH), under a cooperative agreement withthe Agency for Toxic Substances and Disease Registry (ATSDR), issued a Preliminary HealthAssessment (PHA) for the site. IDPH concluded, based on review of the PA/SI, that the site was apotential public health concern. A risk to human health existed because of the likelihood ofexposure to hazardous substances via groundwater, surface water, and soil. The PHA recommendedthat further environmental characterization and sampling of the site (as well as impacted off-siteareas) 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 wereinstalled in the alluvial aquifer to determine the extent of groundwater contamination. Siteassessment was performed to define the extent of metal contamination in lagoon sludge, and toestablish whether heavy metals were migrating from the two aeration lagoons. An inventory of allchemicals remaining at the site was also conducted. During the RI/FS, EPA was informed that, in1988, two employees who were working in a manhole associated with the waste treatment systemdied 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 primaryclarifier sludge, containment of discarded acids and tanning solutions, and a cursory cleaning of thehide-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 wasrestricted by a chain-link fence approximately 10-feet high. Signs were posted at the entrance andother places on-site to inform the public about the restricted area.

The 1990 PHA concluded that further environmental characterization and sampling of the site wasnecessary because of the potential risk to human health from exposure to hazardous substances viagroundwater, surface water, and soil. Since that time, extensive characterization and sampling haveoccurred at the site. Removal actions at the site have abated the potential risks of exposure to sitecontaminants and associated physical hazards. Contaminated source areas have been remediated.

The groundwater contamination has been monitored since 1985 and a subsequent assessment wascompleted in 1997. It was concluded that there is no risk to human health and the environment fromthe 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 ofWoodbury 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 anindustrial area known as the Port Neal Industrial District 1.5 miles west of U.S. Interstate Highway29 and approximately 1.5 miles northeast of the Missouri River.

In December 1968, Needham Packing Company acquired the site, and ownership of the site wasthen transferred to the municipality of Sioux City, Iowa. At that time the site was leased back toNeedham 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. Verylittle chrome tanning of hides occurred until Needham Packing Company changed its name toFlavorland Industries in 1973. At that point in time, Flavorland Industries increased its chrometanning operations, and by 1976, chrome tanning operations accounted for approximately 40 percentof facility operations.

Ownership of Flavorland Industries changed in 1974. In December 1976, labor disputes coincidedwith the closing of the plant. In April 1978, the municipality of Sioux City transferred ownershipback to Flavorland Industries. Flavorland Industries immediately sold the property to MAT. MATused 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 companychanged its name to U.S. Tanning Company, Inc. U.S. Tanning Company continued the "throughthe blue" tanning process until approximately November 1989, at which time all hide processingoperations and other business activities ceased.

In 1979, approximately 900 cubic yards of sludge were disposed of in an unlined trench on theproperty. The U. S. Environmental Protection Agency (EPA) conducted a PreliminaryAssessment/Site Investigation (PA/SI) in 1985. Sediment chromium concentrations within thedisposal trench and from an Oxbow Lake on-site were 47,000 milligrams per kilogram (mg/kg) ofsediment and 5,400 mg/kg, respectively. Chromium was detected in two on-site monitoring wellsabove the Maximum Contaminant Level (MCL) for total chromium, which was then set at 50micrograms 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 backgroundlevels.

In March 1986, the U.S. Environmental Protection Agency (EPA) conducted a follow-up siteinvestigation (SI) to determine if there had been a release of contaminants from MAT's wastedisposal trenches into the groundwater. The SI included a geophysical survey, the installation offive on-site monitoring wells, collection of seven on-site groundwater samples, and two off-sitegroundwater samples to represent background conditions. Results of the SI indicated groundwaterunderneath the site contained arsenic, barium, chromium, lead, and manganese above backgroundlevels. In February 1987, EPA sampled four of the five on-site monitoring wells and two off-sitebackground wells. Elevated levels of arsenic, barium, cadmium, chromium, and lead were detectedin the on-site wells. These levels had generally increased since 1986. Because of the new data, EPAplaced 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 ofarsenic, barium, cadmium, chromium, and lead.

MAT was finalized for inclusion on the NPL in March 1989 (2). On December 2, 1989, anAdministrative Order to U.S. Tanning was issued to direct them to perform removal actions and aRemedial Investigation/Feasibility Study (RI/FS) at the MAT site. U.S. Tanning failed to complywith the order as all business ceased at the facility in November 1989. In September 1991, a Recordof Decision (ROD) was signed. Concurrent investigations into MAT operations informed EPA thattwo personnel deaths occurred when the plant was operational in 1988. The plant personnel diedfrom being exposed to hydrogen sulfide gas after entering a manhole associated with the wastewatertreatment system. This information warranted air monitoring for acute levels of toxic gases andfurther investigations to confirm their continued presence.

From July-August 1990, a Remedial Investigation (RI) was conducted by the Technical AssistanceTeam (TAT) from E&E/FIT at the MAT site. Media investigated for contamination at the siteincluded surface waters and sediments in Oxbow Lake, which crosses the site; surface andsubsurface soils in a sludge disposal trench area; liquids and sludge in the east and west aerationlagoons, 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 ofgroundwater contamination. From May-December 1990, TAT also conducted a site assessment todefine the extent of metal contamination in the lagoon sludge, establish whether heavy metals weremigrating from the two aeration lagoons, and compile an inventory of all chemicals remaining onsite.

During the spring of 1991, EPA re-sampled the groundwater monitoring wells at the site toeliminate 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 byMarch 1991 (Figure 6). Other activities included the characterization of subsurface soils in theformer 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 cleaningof the interior of the hide processing building.

The volume of surface soil containing chromium was estimated to be 12,000 cubic yards. It wasestimated that approximately 1,290 tons of subsurface soils containing total chromiumconcentrations above 2,000 parts per million (ppm) were excavated from the sludge disposal trenchand stockpiled on-site on a 40 millimeter polyvinyl chloride synthetic liner. Dust and debris on thefloors of the hide processing and filter press building were also swept up and stockpiled with theexcavated material from the sludge disposal trench. Sludge from the aeration lagoons and tank werealso characterized. Approximately 15 cubic yards of sludge from the primary clarifier was removedand stockpiled on-site. The liquid portion had been removed from the primary clarifier andtransferred to the east aeration lagoon.

Approximately 5,000 gallons of chromium sulfate solution were treated with calcium hydroxide andleft to precipitate the chromium out of solution. The chromium precipitate, considered to be ahazardous waste, was stored in a tank in the hide processing building. Another tank containingapproximately 300-500 gallons of sulfuric acid was also found on the roof of the main facilitybuilding. 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. Theremedial actions selected included in-situ immobilization of densely-contaminated sediments in theeast and west aeration lagoons and the northeast field, and the placement of soil-clay caps over theless densely-contaminated source areas. Water in site-impoundments was treated in compliancewith National Pollution Discharge Elimination System (NPDES) permit criteria. After water wasremoved from the impoundment areas, the areas were immobilized in-situ with an auger system thatmixes a solidifying agent and additive directly into the contaminant matrix, thereby solidifying andstabilizing the matrix.

The impoundments were backfilled, capped with clay soil, and graded to reduce wateraccumulation. A soil-clay cap was also placed over the polishing basin. Top soil was added to theimmobilized 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 wasrestricted by a chain-link fence approximately 10-feet high. Signs were posted at the entrance andother 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 andassociated physical hazards. Contaminated source areas have been remediated.

The groundwater contamination was monitored from 1985 to 1997. It was concluded that there isno risk to human health and the environment from the groundwater, and the remaining contaminants will not adversely impact groundwater quality.

C. Site Visits

On March 17, 1993, Iowa Department of Public Health (IDPH) staff visited the MAT site. Areas ofspecial interest were the soil stockpile area and the location of the previous burial trench, concreteaeration basin, east and west aeration lagoons, the polishing basin, site buildings, and otherstructures. The on-site and off-site Oxbow Lake, on-site and off-site monitoring wells, off-siteprivate wells, and the surrounding land and building structures within one-half mile of the siteboundary were located. Access to the on-site area was not fully restricted. The entrance to the MATsite was restricted by a chain-link fence approximately 10 feet high; however, the fence onlyrestricted vehicles from driving onto the property and did not restrict trespassers from entering byfoot. Signs were posted at the entrance and a few places on site to inform the public about therestricted area. During the site visit, it was evident that trespassers had entered the property and hadhunted near physical hazards. Evidence indicated that children lived on farms where some of theoff-site wells were located. The site was obviously attractive to duck hunters; spent shot-gun shellcasings were found near the east and west lagoons, the polishing basin, and the on-site Oxbow Lakearea.

On June 16, 1996, IDPH and IDNR staff revisited the site. Entrance to the site was restricted by achain-linked fence approximately 10-feet high. Signs were posted at the entrance and other placeson-site to inform the public about the restricted area. The site was well vegetated. PreviousRemoval 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 contaminantsand 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


The MAT site is located in Woodbury County, Iowa. Municipalities located close to the site are thetowns 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 apopulation of approximately 367 people, and the city of Sergeant Bluff has approximately 2,772people. For both towns, approximately 35% of the population are below the age of 18 years; whileapproximately 10% are 65 years of age or older. Also, for both towns, approximately 97% of thepopulation is White with the other 3% of the population divided equally among Asians, Blacks, andHispanics.

Land Use

The immediate area surrounding the MAT site is used for industrial and agricultural purposes. Thesite 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 locatedwithin the Missouri River Valley, which is extensively farmed for grain crops such as corn andsoybeans. Pastureland comprises the rest of the agricultural land uses. Local ecology around thesite 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 andBrowns Lake State Park. Both of these areas are located south-southeast of the site (Figure 4).

E. Health Outcome Data

Using state health databases, special studies, or other relevant health outcome databases, it may bepossible to determine whether certain health effects are higher than expected in areas surroundinghazardous waste sites. This section introduces the databases available.

IDPH maintains the vital statistics (birth, death, and fetal death reports). The University of Iowamaintains the cancer and birth defects registries. The state cancer registry has collected data since1969. The birth defects registry has collected data since 1985.

Although information derived from the state cancer and birth defects registries may make it possibleto determine if health effects are related to exposure from site contaminants, people have not beenexposed to the contaminants of concern at this site. Therefore, no adverse health outcomes would beexpected. 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 publicmeeting in Sergeant Bluff on June 28, 1990. At this meeting, representatives from EPA, IDNR, andIDPH presented information and answered questions about the site and the remedial alternativesunder consideration. Residents interviewed by IDPH staff said they did not know of anyone whohas experienced health problems associated with the site. However, the residents did want to benotified if any health risks were identified during future site investigations. There were no specifichealth concerns voiced by the community during the public meeting.

During the public comment period from July 1, 1994 through August 1, 1994, the following twopublic health concerns were received about the site:

  • What are the long-term health effects from hydrogen sulfide being present at the site?

  • What are the long-term health effects of drinking contaminated water?


Tables in this section list contaminants of concern at the MAT site that were identified during theRI/FS process. However, their listing does not imply that a health threat exists. An evaluation ofcontaminants in subsequent sections determines whether exposure has occurred and if such exposurehas public health significance. IDPH and ATSDR select the contaminants of concern based on thefollowing 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 withbackground concentrations, (4) comparison of site-related concentrations with health assessmentcomparison 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 healtheffects will result from exposure, but indicates that a contaminant must be further evaluated in thepublic health assessment process.

Contaminants requiring further evaluation are selected by using medium-specific comparisonvalues. These values include Environmental Media Evaluation Guides (EMEGs), Reference DoseMedia Evaluation Guides (RMEGs), Cancer Risk Evaluation Guides (CREGs), and other relevantenvironmental guidelines.

EMEGs are estimated contaminant concentrations in the environment at which daily exposurewould be unlikely to result in non-cancerous health effects. EMEGs are calculated from ATSDRMinimal Risk Levels (MRLs). MRLs are estimates of daily exposure to contaminants below whichnon-cancerous, adverse health effects are unlikely to occur. If no MRLs exist for a contaminant, acomparison value, Reference Dose Environmental Media Guide (RMEG), is calculated from anEPA Reference Dose (RfD). A RfD is an estimate of the daily exposure to a contaminant that isunlikely to result in non-cancerous, adverse health effects. CREGs are estimated contaminantconcentrations in the environment that are based on the Cancer Slope Factor. The Cancer SlopeFactor is the estimated probability that, in one million people exposed, one excess cancer (one cancerabove the expected background number) will result because of a lifetime of exposure to thecontaminant. EPA Maximum Contaminant Levels (MCLs) represent contaminant concentrations inpublic drinking water supplies that EPA deems protective of public health; however, in derivingMCLs, EPA must take into consideration the technical feasibility and economics of water treatment. MCLs are regulatory concentrations.

A. On-Site Contamination

The nature of surface soil, subsurface soil, surface water, and groundwater contamination resultingfrom sludge disposal and wastewater treatment facility releases to soils is discussed in the followingsections. Analytical results of polishing basin sludge gases, sludge and liquids, and aeration lagoonsludge gases and liquids are also discussed.

A large amount of soil had been stockpiled at the site. That soil contained chromium, which was notspeciated, but was assumed to contain approximately 0.1% hexavalent chromium. This percentagewas determined during the Remedial Investigation (1).

Although the presence of chromium at the site prompted historic concern and actions, the levels ofchromium, assuming 0.1% hexavalent chromium, do not exceed ATSDR comparison values. Therefore, chromium will not be further evaluated in this document.

Surface soil

During the July and August 1985 Site Investigation (SI), four surface soil samples were collectedfrom a cornfield (field #1) where sludge was incorporated into the soil. The cornfield is directlynorth 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). In1990, during the RI, surficial soil in the disposal and suspected surficial contamination areas weremeasured 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 (Figure6). Three composite samples of surficial soil were collected from each sample section. Arsenic wasfound at its highest level on the southwest corner of the site. However, arsenic levels are comparableto background levels.


Location Concentration Comparison Value
Arsenic Field #1 37.0 0.4 CREG
Manganese Field #1 800 300 RMEG
Arsenic S.W. corner 10 0.4 CREG

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

Subsurface soil

Nine subsurface soil samples were collected at four different boring locations (B1-B4) during the1985 SI. Samples from borings B1 and B2 were collected at 11 feet, 16 feet, and 21 feet. Samplesfrom borings B3 and B4 were collected at 11 feet and 16 feet. Subsurface soil results revealedheavy 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 theinstallation of shallow and intermediate well borings. The vertical extent of contamination was notclearly defined in subsurface soils because there was no consistent trend of individual contaminantsby depth. Metal concentrations were generally the highest in the upper 8.5 feet of soil across thesite. 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.


Comparison Value
Arsenic B-1/12S 29/52 0.4 CREG
Manganese B-1/12S 1,200/1,500 300 RMEG
Beryllium 13S 2.3 0.2 CREG

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

Surface water drainage at the MAT site primarily comes from the primary and final clarifiers, eastand 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 Kindand Knox (K&K) facility to the north also flows southward into Oxbow Lake. This drainage couldinfluence contaminant concentrations in, and south of, Oxbow Lake.

Surface water samples were collected from MAT's Oxbow Lake at a point directly north of theprimary clarifier (AAJ03019), near the north end of the drainage ditch (Figure 4). Backgroundsurface water samples were also collected from Browns Lake. Surface water in Oxbow Lakecontained levels of arsenic, barium, cadmium, manganese, and vanadium at concentrations abovecomparison values (Table III). Lead, mercury, nickel, and zinc were not at levels above comparisonvalues, but are included in the table to illustrate comparisons between surface water andgroundwater 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, onlymanganese was detected above comparison values. Barium was not detected above comparisonvalues, 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.


Location Concentration Comparison Value
Arsenic Oxbow Lake 10.0 0.02 CREG
Barium Oxbow Lake 890 700 RMEG
Cadmium Oxbow Lake 5.0 2 EMEG
Lead Oxbow Lake 16 50 MCL
Manganese Oxbow Lake 380 50 RMEG
Mercury Oxbow Lake 0.2 2 MCL
Nickel Oxbow Lake 40 100 LTHA
Vanadium Oxbow Lake 50 20 LTHA
Zinc Oxbow Lake 30 3,000 RMEG
Barium Oxbow Lake 650 700 RMEG
Manganese Oxbow Lake 1,100 50 RMEG

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 andshallow groundwater flow in the southern area of the K&K company could contribute tocontamination of the polishing basin and Oxbow Lake. Seepages from the polishing basin, OxbowLake, 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 goodrepresentation of groundwater quality. When elevated metal concentrations were detected ingroundwater, a recommendation was made to further characterize the extent of groundwatercontamination.

During the 1986 SI, EPA installed five monitoring wells in the alluvial aquifer and collected ninegroundwater samples (including one on-site drinking water well and two off-site backgroundsamples). Two residential wells approximately 2 miles north of the site were used as backgroundsamples. A geophysical and magnetometer survey of the site was also conducted at that time. Thesurveys were conducted in order to determine the best locations for five monitoring wells. Anelectromagnetic (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 tothirteen feet below the surface. The material was not encountered in any of the other monitoringwell installations.

Groundwater samples were analyzed for total and dissolved metals. Groundwater from the sitecontained arsenic, lead, manganese, chromium, and vanadium. However, only arsenic and leadwere considered to be above background levels, while arsenic, lead, manganese, and vanadium wereabove 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 microgramsper liter (g/L) and 680 g/L, respectively.

In August 1989, MW-1 was again sampled by contractors for U.S. Tanning. Split samples werecollected, and analyses for total and dissolved metals were conducted. Contaminants present atlevels above comparison values were arsenic at 40 g/L dissolved(d) and 48 g/L total(t), barium at878 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 thissampling event is available.

For the RI (1990-1991), 18 additional wells were installed in the alluvial aquifer near the MATdisposal areas and Oxbow Lake to assess the nature and extent of groundwater contamination in thealluvial 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. Arsenicand zinc levels were only slightly above background levels.

Additional groundwater samples were collected by EPA in April 1991 to complete data gaps createdby unusable data. The 18 wells originally installed during the RI were re-sampled and analyzed fortotal 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.


Contaminant Location (Yr.) Groundwater (Yr.) Comparison
1985-SI 1986-SI 1985-SI 1986-SI
Arsenic B-2 MW-1 300 33 0.02 CREG
Barium B-1   9,000   700 RMEG
Cadmium B-2   16.0   2 EMEG
Lead B-2 MW-4 830 78 50 MCL
Manganese B-2 MW-5 29,000 3,000 50 RMEG
Mercury B-2   2.1   2 MCL
Nickel B-2   1,100   100 LTHA
Vanadium B-2 MW-5 1,500 100 20 LTHA
Zinc B-2   4,000   3,000 RMEG
(Year) 1990-RI 1991-RI 1990-RI 1991-RI  
Arsenic MW5/26S MW-9 23J*/25 56.5 0.02 CREG
Barium MW-5 S-26 1,100* 3,240 700 RMEG
Manganese MW-5 S-26 6,800* 22,000 50 RMEG
Beryllium 17S S-13 2.0 4.22 0.008 CREG
Cadmium 25D S-26 11.0 10.2 2 EMEG
Chloride 18S   2,100,000   250,000 MCL
Fluoride 18S   8,070   600 RMEG
Lead   S-26   86 50 MCL
Nickel   S-20   888 100 LTHA
Vanadium   S-13   243 20 LTHA
Zinc 9S/11D   120/370   3,000 RMEG

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 potentialcontaminant migration, evaluate potential environmental risks, and evaluate remedial options. Theinvestigation focused on sampling the liquid and sediment (sludge). Sludge and liquids weresampled between May and September 1990, and the samples were analyzed for major ions, totalmetals, volatile organic compounds, and semi-volatile organic compounds. The basin was dividedinto eleven one-acre sections to characterize the spacial distribution of contaminants. Compositesamples of each one-acre section were analyzed. Concentration ranges for each contaminant ofconcern found are listed in Tables V and VI.

Sludge samples were collected from a depth of zero to six inches (zero being the liquid-sedimentinterface), six inches down to refusal, and at the bottom of the polishing basin. Contaminants thatwere found in the sludge at concentrations above comparison values were antimony, arsenic, andmanganese (Table V). Liquid samples were collected in the zone of the liquid column from thesurface to a depth of approximately six inches at all sampling locations. Contaminants that werefound in the liquid at concentrations above comparison values were ammonia, chloride, fluoride, and manganese (Table VI).


Contaminant Concentration Comparison Value
Antimony < 9.4 - 54 20 RMEG
Arsenic < 3.4 - 9.0 0.4 CREG
Manganese 400 - 1200 300 RMEG

mg/kg - milligrams per kilogram
RMEG - Reference Dose Media Evaluation Guide
CREG - Cancer Risk Evaluation Guide
Data from the Remedial Investigation


Contaminant Concentration Comparison Value
Ammonia 400-58,900 3,000 EMEG
Chloride 5,400,000-6,160,000 250,000 MCL
Fluoride 14,400-24,900 600 RMEG
Manganese 21-1,600 50 RMEG

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 liquids

The east and west aeration lagoons were sampled in September 1990 to characterize the liquidnature of contamination in the lagoons. A limited data base of sampling information was availablebecause only one liquid sample was obtained from each lagoon. Each sample was used to evaluateif 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 fromthe west lagoon was collected from a wooden pier leading to an outlet structure. Liquid in the eastlagoon ranged from approximately 4-7.5 feet in depth, while liquid in the west lagoon wasapproximately 1.5 feet deep. Contaminants of concern were total and dissolved chromium,ammonia, chloride, and fluoride (Table VII).


Contaminant Concentration Comparison Value
East West
31,000/20,000 2,300/2,300 10,000 RMEG
Ammonia 15,300 153,000 3,000 EMEG
Chloride 4,890,000 10,000,000 250,000 MCL
Fluoride 14,300 198,000 600 RMEG

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

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 wasperformed on sediment samples collected from the east and west aeration lagoons and the polishingbasin. Impoundmentoff-gas was sampled in an enclosed space by dragging a five-gallon bucketattached to a rope through sludge surfaces and air sampling the head space within the bucket. IDNRhad some questions regarding the validity of this technique.This method allowed only the upperone foot of each impoundment to be sampled. Air samples for hydrogen sulfide and cyanide gaswere deleted from the sampling agenda because of the inaccuracy associated with the samplingmethod. Air sampling for hydrogen cyanide was determined to be compromised by levels ofhydrogen sulfide in the sludge. Later, analytical results and air monitoring data indicated thathydrogen cyanide was not present in the sludge off-gases. However, hydrogen sulfide was detectedin sludge off-gases. Air monitoring results are summarized in Table VIII. The comparison valuefor 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).


Hydrogen Sulfide Air Monitoring of Sludge off-gas, per IDNR 08/03/94 (mg/m3)
Time (min) West Lagoon East Lagoon Polishing Basin
1   298 392
2 64 568 709
3 45 682 839
4 37 682 892
5 27 643 831

mg/m3 - milligrams per cubic meter
Data from the Field Sampling Trip Report (11/92)

B. Off-Site Contamination

The contamination measured off-site was performed primarily to determine the extent ofcontamination from possible on-site sources and to determine the degree of background levels of theelements in the surrounding environment. Although some elements were measured at levels abovecomparison values, most levels of elements found are considered to be within naturally occurringlevels for the environmental media sampled. Because of safety factors calculated into comparisonvalues, a number of the comparison values are lower than levels of elements found naturally in soils and water.

Surface and subsurface soil

Background surface and subsurface soil samples were taken during the SI and RI between 1985 and1990. Contaminants that exceeded comparison values in surface and subsurface soils are listed inTable IX. Arsenic and manganese were both detected at levels above comparison values in surfacesoils off-site near Browns Lake. They were also found at levels above comparison values insubsurface soils during the drilling of off-site monitoring wells 1S and 3S. Beryllium was detectedat a level above comparison values during the drilling of 3S. However, all concentrations detectedin the surface and subsurface soil locations off-site fall within naturally occurring concentration ranges.


Location Concentration Comparison
Surface Subsurface Surface Subsurface
Arsenic Browns
3S 15 14 0.4 CREG
Manganese Browns
1S 330 1,200 300 RMEG
Beryllium   3S   <1.3 0.2 CREG

mg/kg - Milligrams per kilogram
CREG - Cancer Risk Evaluation Guide
RMEG - Reference Media Evaluation Guide
Data from the Site Investigation and Remedial Investigation

Surface water and groundwater

Contaminants in off-site surface water and groundwater were detected at levels exceedingcomparison values during the 1985-1991 sampling period (Table X). However, the levels detectedwere considered to be within background ranges. Arsenic, cadmium, and vanadium were detected insurface water in Browns Lake, while barium and manganese were detected at their highest valueapproximately mile from Oxbow Lake. Arsenic, barium, beryllium, cadmium, chloride, fluoride,nickel, vanadium, and zinc were all detected at levels above comparison values in off-sitemonitoring wells near the site. However, all the monitoring wells except the Terrachem companywell are considered up-gradient from the alluvial groundwater flow direction at the site. TheTerrachem well is also a much deeper well and taps the granite aquifer southwest of the site. Thelevels of metals detected in that well, including the 10,000 g/L of manganese, were withinestablished background levels for that aquifer. Wells 903S and 3S are up-gradient of the site, butdown-gradient from the K&K company. No metals were detected in those wells above background concentrations.


Location Surface Water
Comparison Value
Surface Water Groundwater
Arsenic Browns
3S 10.0 U 15 0.02 CREG
Beryllium   1S NA 17 0.008 CREG
Barium mi.
North of site on Oxbow Lake
903S 7,000 4,400 700 RMEG
Cadmium Browns
1S 5.0 U 12 2 EMEG
Chloride   903S NA 2,830,000 250,000 MCL
Fluoride   903S NA 6,850 600 RMEG
Manganese mi. South of site on Oxbow Lake Terrachem #1 640 10,000 50 RMEG
Nickel   1S NA 170 100 LTHA
Vanadium Browns
1S 50.0 U 170 20 LTHA
Zinc   1S NA 200 3,000 LTHA

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 proximityof 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 (emissionrates) of toxic chemicals to the environment (air, water, land, or underground injection) by industrieswith 10 or more full-time employees, in accordance with federal law. The TRI did containinformation 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, sodiumhydroxide (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 intothe MAT site and eventually to the Missouri River. Surface water possibly leaches into the alluvialaquifer 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 wasobtained for this public health assessment. Field blanks, trip blanks, duplicate samples, and/or splitsamples were analyzed.

In preparing this public health assessment, IDPH relied on the information provided in thereferenced documents and assumes that adequate QA/QC measures were followed with regard tochain of custody, laboratory procedures, and data reporting. The validity of the analyses andconclusions drawn in this public health assessment were determined by the availability andreliability of the referenced information.

Furthermore, during the preparation of this public health assessment, IDPH concluded that the data was adequate and reliable.

E. Physical and Other Hazards

No physical or other hazards currently exist at the site.


The environmental and human components that lead to possible human exposure are evaluated andpresented in this section of the public health assessment. IDPH and ATSDR determine whetherpeople have been exposed to contaminants from the site in the past, are being exposed now, andwhether they could be exposed to contaminants in the future. A completed exposure pathwayconsists of the following elements: a source of contamination, transportation of the contaminantthrough an environmental medium, a point of exposure, a route of human exposure, and an exposedpopulation. 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 aboveelements is missing, although risk of exposure may still exist. Potential pathways indicate thatexposure from a contaminant may have occurred in the past, may be occurring, or may occur in thefuture. 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

Subsurface soil

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. Unprotectedremedial workers could have came into contact with the metals in the subsurface soils whileexcavating areas of contamination. The workers could have inhaled and ingested fugitive dust andcould have came into direct contact with the metals. If surface soils contained the same levels ofmetals, then trespassers, as well as workers, could have came into contact with the metals throughinhalation and ingestion of the soil as well as through direct skin contact.

Surface water and groundwater

Contaminated surface water has been removed from the site. Thus, there is no longer a source forexposure. However, past exposure to contaminated surface water could have occurred. Somemetals 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 andcould 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 thecontaminated aquifers. Furthermore, exposure to groundwater contaminants is unlikely to occur as long as drinking water wells are not tapped into contaminated aquifers.


A. Introduction

In this section, we will discuss the health effects that may occur in persons exposed to specificcontaminants, 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 beexposed by breathing, eating, or drinking the contaminant or by contact with contaminated water orsoil. To understand the health effects that might be caused by a specific chemical, it is helpful toreview factors related to how the human body processes such a chemical. Those factors include theexposure 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 possiblehealth effects that exposed individuals might experience. No completed exposure pathways tocontaminants have been identified at this site. Therefore, no illnesses are expected to occur as aresult of site contamination. A potential exposure pathway, however, has been identified. Thisexposure pathway involves the possible future use of contaminated groundwater.

B. Toxicologic Evaluation

Heavy metals (arsenic, barium, beryllium, cadmium, lead, manganese, nickel, and vanadium) weredetected at concentrations above comparison values in on-site groundwater. Currently, no privatewells tap into the contaminated aquifer. Thus, as long as this remains the case, no one shouldbecome exposed to contaminated groundwater.

Private wells are believed to tap the deeper aquifer, but are not likely to become contaminated bymetals 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 withinnaturally occurring levels for the area. Only manganese and chlorine were present in the deeperaquifer at levels of health concern (and this appears to be due to the naturally occurring levels in thearea).

Manganese is a natural component of most food and water. There is no direct evidence thatmanganese is beneficial or essential in humans, but ingestion of manganese compounds is known tobe required for good health in animals (14). The estimated dose for a person exposed to manganeseat the maximum level of 10,000 g/L found in on-site monitoring wells would exceed the RfDestablished by EPA (14). Ingestion of up to 5,000 g manganese each day is normal (15). The RfDis derived by incorporating uncertainty factors and may result in an estimate with uncertaintyspanning an order of magnitude (15).

Ingestion of the maximum levels detected in monitoring wells slightly exceed a dose above thenormal daily diet intake; the dose also exceeds the RfD. For that reason, very sensitive people mayexperience some adverse health effects. Some symptoms may include weakness, stiff muscles, andtrembling 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 outcomeswould 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 healthconcerns were received about the site. The following are the questions (concerns) received and their respective responses.

  1. What are the long-term health effects from hydrogen sulfide being present at thesite?

In a limited study (data not shown) hydrogen sulfide was not detected in ambient outdoor air at thesite so no long-term effects are expected. Testing was performed in a sealed container on gasescoming out of sludge from the polishing basin and aeration lagoon. The air in enclosed on-sitespaces may be hazardous for persons entering them. Note: All manhole covers have been weldedshut. In the past, two workers were killed by entering enclosed spaces on-site because they did not monitor the air for toxic gases beforehand.

  1. What are the long-term health effects of drinking contaminated water?

Health effects for someone drinking contaminated groundwater would vary depending on thecontaminants, and the concentrations they were exposed to. No completed exposure pathways forcontaminated groundwater (and other media) exist. Therefore, no short- or long-term health effects from drinking contaminated water are expected.


ATSDR's Child Health Initiative recognizes that the unique vulnerabilities of infants and childrendemand 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 fromwaste sites and emergency events. They are more likely to be exposed because they play outdoorsand they often bring food into contaminated areas. They are shorter than adults, which means theybreathe dust, soil, and heavy vapors close to the ground. Children are also smaller, resulting inlarger doses of chemical exposure per body weight. The developing body systems of children cansustain permanent damage if toxic exposures occur during critical growth stages. Most importantly,children depend completely upon adults for risk identification and management decisions, housingdecisions, 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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