Superfund Information Systems: Site Profile

Superfund Site:


Cleanup Activities

On this page:

On related pages:


The 132-acre Eagle Zinc Co Div T L Diamond site is located in Hillsboro, Illinois. Part of the site is covered by buildings. Active industrial operations at the site ceased in 2003. The site’s remedies have been selected. Investigations to inform the design of the remedies are ongoing. The City of Hillsboro has indicated interest in acquiring the site property for use as an industrial park following cleanup.

Top of Page

What Is Being Done to Clean Up the Site?


From 1912 to 2003, the site was used for smelting and for manufacturing of sulfuric acid, zinc oxide, and leaded zinc oxide. Residuals from the plant operations were placed across the site and in residue piles that have been categorized based on the processes that generated them. The Site originated as a zinc smelter facility under the name Lanyon Zinc Company in 1912. Lanyon Zinc Company produced various smelting products including zinc and sulfuric acid. The facility was then purchased by Eagle-Picher Industries in 1919. Eagle-Picher Industries operated and produced similar products until about 1935. During the early 1920s Eagle-Picher Industries began manufacturing zinc oxide and lead zinc oxide. Manufacturing of lead zinc oxide continued until around 1958 and production of zinc oxide continued until around 1980 when the facility was purchased by Sherwin-Williams Company. In 1984, the facility was sold to Eagle Zinc Company, a division of T.L. Diamond and Company. Eagle Zinc continued the production of zinc oxide until 2003 when the facility ceased industrial operations.

According to historical documents, during industrial operations large amounts of ore and smelter waste were stored onsite. The leaded zinc oxide that was made at the site was produced using the American process, which combined zinc ore concentrates with high levels of impurities. Waste materials generated from this process included slag rotary kiln residue, muffle dross, metallic zinc particles, and refractory bricks. Significant portions of the site are currently covered with smelter waste and other materials associated with historical smelting operations. An estimated 43,500 cubic yards of residue waste currently resides onsite in 15 residue piles. Residue is also spread across the Site, and the residue thickness ranges from a few inches thick to 28 feet thick based on soil borings; totaling approximately 210,000 cubic yards of residue. In addition, 43,500 cubic yards of residue are consolidated into 15 piles around the Site.

Enforcement History

The zinc smelting and zinc oxide production facility was listed on the Comprehensive Environmental Response Compensation and Liability Information System (CERCLIS) in June 1981 as a discovery action. Sherwin-Williams notified EPA that slag/residual material had been disposed of onsite. Results from Illinois EPA sampling indicated that the waste materials were not hazardous wastes and that the Site was not subject to the Resource Conservation and Recovery Act (RCRA) permit requirements. Illinois EPA took additional samples of the surface water from the storm water discharge and found some metals (zinc, iron, lead, and copper) exceeded the state surface water quality standards on more than one occasion. Therefore, Sherwin-Williams received a notice of violation from the Illinois EPA, which resulted in the removal of approximately 18,000 tons of residue materials from about 10 acres of the site.

In April 1998 Eagle Zinc removed a 500-gallon gasoline underground storage tank and submitted a leaking underground storage tank (LUST) report to Illinois EPA. An investigation by Illinois EPA followed the report. No detections of benzene, toluene, ethyl benzene, and xylene (BTEX) compounds were found in the soil or groundwater. The groundwater was monitored for BTEX compounds for three years. In 2004 Eagle Zinc received a No Further Remediation letter for the former LUST.

In May 1998, Eagle Zinc entered into an Interim Consent Order with the Illinois Attorney General and Illinois EPA. The Consent Order required a groundwater monitoring program, a soil sampling program. and a storm water pollution prevention plan (SWPP). The SWPP led to the determination the site was subject to National Pollutant Discharge Elimination System (NPDES) storm water permitting requirements. In 2000, Eagle Zinc was issued a permit that required monthly monitoring of the NPDES Outfall and an annual inspection report. The permit was terminated upon closure of the facility in 2003.

In 2001, EPA issued an Administrative Order on Consent (AOC) to potentially responsible parties (PRPs) Eagle Zinc, Sherwin-Williams, and Eagle Picher to conduct the Remedial Investigation (RI) and Feasibility Study (FS) for the site. Under this agreement the companies submitted the following draft reports: RI Report (January 2005), RI Addendum (February 2006) and FS (May 2006). The Illinois EPA completed the Hazard Ranking Score (HRS) for the site in March 2007. Based on the Site’s overall score, Illinois EPA recommended that the Site be placed on the National Priorities List (NPL). The Site was placed on the NPL in September 2007.

In 2007, T.L. Diamond signed a cash-out settlement with EPA for $750,000, which helped fund the OU 2 investigation and the OU 1 remedial design. EPA is currently negotiating with Sherwin-Williams to recover additional cleanup costs and EPA has filed a claim for its costs in the Eagle-Picher bankruptcy proceedings.

Previous Investigation Activities

In 1982, Sherwin-Williams conducted an environmental risk assessment of the Site, using data collected two years prior. Based on the sampling data no environmental risk was identified. Unfortunately, an accurate map of the soil sampling locations taken for this assessment is not available. In 1984, a preliminary site assessment (PA) was conducted by Illinois EPA and submitted to EPA. The report concluded that the soil samples from the early 1980s were not hazardous waste and therefore not subject to RCRA regulations.

In 1993, Illinois EPA conducted an expanded site inspection (ESI) in order to provide significant documentation to support the Site CERCLA Hazard Ranking System (HRS) record. The ESI included 28 sediment, residue, and soil samples from both onsite and offsite locations. Background samples were collected from Butler, a town close to Hillsboro. The sample results indicated that there were high concentrations of heavy metals like cadmium, copper, and zinc in the soil and residue piles. The ESI report was completed in 1996. A few years later, in 1998, the LUST investigation took place; no BTEX contamination was detected in the soil or groundwater. In 1999, groundwater monitoring was required under a State Consent Order. The results show that the groundwater exceeded Illinois Class I groundwater standards for total iron and sulfate. The high levels of iron and sulfate in the water led to the initiation of a complete RI/FS under the 2001 AOC between EPA and the T.L. Diamond (Eagle Zinc), Sherwin-Williams, and Eagle Picher.

The RI was conducted between 2001 and 2005. The RI investigated the Site’s physical characteristics, identified sources of contamination, described the nature and extent of contamination, and evaluated the risk to human health and the environment. Field investigation activities included samples from the groundwater, residue piles, and onsite and offsite surface and subsurface soil. The samples were analyzed for volatile organic compounds (VOCs), semi-VOCs, polychlorinated biphenyls, inorganic constituents, and toxic characteristic leaching procedure (TCLP) and/ or synthetic precipitation leaching procedure (SPLP) characteristics. Air modeling and soil deposition calculations were also created to determine if there were any airborne emissions of concern from the residue piles.

The 2005 RI and RI addendum compared the chemical concentrations on the Site to conservative screening levels in order to identify potential chemicals of concern for the residue piles, soil, sediment, surface water and groundwater. Three of the residue piles were categorized as potential areas of concern because the TCLP values exceeded the RCRA hazardous waste threshold, i.e. the contaminants are characteristically hazardous because they are likely to leach from the residue pile materials when exposed to acidic liquid. Other potential areas of concern included isolated soil areas, sediment and surface water in limited portions of the eastern and western drainage ways, and the groundwater in the south west portion of the Site and a small offsite area. A human health risk assessment (HHRA) and a screening level environmental risk assessment (SLERA) were conducted as part of the 2005 RI. The ecological risk assessments concluded that although there may be some adverse impacts to wildlife, the impacts were negligible. As noted below, EPA and Illinois EPA later reevaluated the SLERA and HHRA conducted under the 2001 AOC to ensure the conclusions were valid. The primary PRPs were unable to complete the FS Report and to address EPA’s comments on the RI Report text because Eagle-Picher filed for bankruptcy and T.L. Diamond dissolved its business. EPA therefore proposed the Site for listing on the National Priorities List (NPL) and completed the RI/FS process. The Site was listed on the NPL in September 2007.

In May 2008, Illinois EPA conducted an independent sampling event at the Site to gather additional information on the levels of contamination in and around the buildings, and in the residue spread across the Site. The field events included the collection of 65 residue samples for X-ray Florescence (XRF) analysis and 10 residue samples for laboratory analysis. These samples were collected from multiple locations near the buildings on the Site and were analyzed for total inorganic constituents. An additional 10 samples of residue were collected for TCLP analysis. The results of the XRF sampling event indicated inorganic contamination exceeding the industrial screening criteria was located in, on, and around the dilapidated buildings. These high levels prompted EPA to prioritize a response action for this portion of the Site. The Site was therefore split into two OUs and an interim ROD was signed September 16, 2009 to address the OU 1. In addition, in late 2008 and early 2009 EPA upgraded and extended the fencing along the eastern and western Site boundaries to further restrict access.

In October 2009, EPA and Illinois EPA decided to conduct a supplemental RI/FS for OU 2 which focused on data gaps in the original RI (2005). The supplemental RI (SRI) evaluated the chemicals of concern (COCs) in groundwater screened beneath the residue piles, evaluated the leachability of the residue in areas between the waste piles, compared the levels of metals seen in the residue and the waste piles, and evaluated the presence of COCs in soil beneath the residue. The SRI compared data from the 2005 RI to the data collected in 2010 and updated the HHRA based on the information. In November 2010, EPA collected 32 residue samples, 11 surface soil samples, 41 subsurface soil samples, 21 surface water samples, 17 sediment samples, and 34 groundwater samples. The samples in each media were analyzed for metals. TCLP and SPLP analysis was conducted for some of the soil and residue samples. The data from 2010 was combined with the data from previous investigations and compiled in the SRI report, which was completed in May 2012. A more in-depth discussion about the findings of the 2012 SRI and the nature and extent of contamination is provided in Sections 5 and 7 of this document.


Top of Page

What Is the Current Site Status?


EPA has changed the cleanup plan for Operable Unit 2 of the Eagle Zinc site. A Record of Decision was issued in September 2012 that called for the cleanup at industrial areas of the site. During remedial design sampling, EPA discovered lead-contaminated soil in a residential area. Changes that differ significantly from the remedy selected in the ROD are summarized the Explanation of Significant Differences  (PDF) (12 pp, 993K). In 2016, EPA issued an ESD to address the cleanup of residential properties. The current ESD shows that the OU2 residential cleanup conforms with the current national lead policy.

 EPA is also establishing a third OU for the 132-acre Eagle Zinc site. OU 1 addressed site contamination associated with the facility buildings and structures. OU 2 addresses contamination in soil, groundwater, surface water, and remaining manufacturing residues on site. OU2 had previously also included impacted sediment in streams flowing from the Site. However, because supplemental investigations have determined that impacted sediment in offsite streams and Lake Hillsboro will require additional evaluation through a Remedial Investigation for potential human health and ecological risks, offsite sediment remediation has been designated as OU3.


Top of Page

Sampling and Monitoring


Top of Page