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Congressional District # 11


EPA ID# ILD062340641
Last Updated: May, 2015

Site Description

The DePue/New Jersey Zinc/Mobil Chemical Superfund Site is located in the Village of DePue, Bureau County, Illinois, and consists of approximately 950 acres. According to the 2010 Census, the Village of DePue's population is 1,838.

The primary zinc smelting facility on the site began operations in 1903 on 175 acres of farmland, but over the years expanded to more than 860 acres as additional plants were added. The original plant produced slab zinc, used in the automobile and appliances industries, and sulfuric acid. Zinc dust was also produced and used as an additive to produce corrosive-resistant paints. In 1967, in response to the increase in the demand for phosphate fertilizer, DePue/New Jersey Zinc constructed a diammonium phosphate (DAP) fertilizer plant. Mobil Chemical leased the DAP and sulfuric acid plants from New Jersey Zinc in 1972 and later purchased the plant in 1975. Mobil ceased manufacturing operations at the plant in August 1987 and the plants were demolished in April 1991.

Two preliminary site assessments were completed in 1980 and 1983, followed by site inspections in 1984 and 1987. The Illinois Environmental Protection Agency (IEPA) conducted an expanded site inspection in March 1993 to gather additional soil, sediment, wastewater, and surface water samples. Based on those evaluations and sampling results, IEPA signed an Interim Consent Order with a group of Potentially Responsible Parties (PRPs) known as the DePue Group on November 6, 1995, to perform various investigations and cleanup actions at the site. The DePue Group, which represents former owners and/or operators of the site, consists of ExxonMobil and CBS Corporation (formerly Viacom).

In 1999, the U.S. Environmental Protection Agency (EPA) formally added the DePue/New Jersey Zinc/Mobil Chemical Superfund Site to the National Priorities List.

To facilitate the investigation and cleanup of contamination, the site has been broken into five (5) areas known as Operable Units, as follows:

• Operable Unit 1, The South Ditch
• Operable Unit 2, Phosphogypsum Stack Area
• Operable Unit 3, The Former Plant Site Area
• Operable Unit 4, Off-Site Soils
• Operable Unit 5, DePue Lake Sediments and Floodplain

Site Responsibility

The site is being addressed through State and PRP actions. IEPA is the lead oversight agency for the site investigation and cleanup, and IEPA interacts directly with the PRPs (the DePue Group). EPA serves as the support agency, reviewing certain work products provided by IEPA.

More detailed site information and current updates on site progress can be found at IEPA's website for the DePue/New Jersey Zinc/Mobil Chemical Superfund Site.

Threats and Contaminants

Several sources for the contaminants have been identified: a residue pile, a zinc slag pile, lithopone waste material ridges, a cinder fill area, contaminated soils, cooling ponds, a discharge ditch, and the gypsum stack. All sources were found to contain elevated levels of metals including zinc, lead, arsenic, cadmium, chromium, and copper. Contamination of a fishery, state wildlife refuge, and wetlands has been documented in Lake DePue.

Cleanup Progress

The November 1995 Interim Consent Order between the State and the DePue Group required the DePue Group to conduct some limited response actions and a Remedial Investigation/Feasibility Study (RI/FS) for the site. The limited response actions included securing the previous manufacturing facility, performing a rigorous dust monitoring and dust control program, and constructing a water treatment plant to treat surface water leaving the plant property and discharging into Lake DePue. The site was secured and dust control implemented during the summer of 1995. In June 1997, the DePue Group completed the construction of the water treatment plant, and it began operating on June 11, 1997. The Interim Consent Order established two sets of discharge limits for the water leaving the treatment plant and for the water entering the lake. The DePue Group was required to meet the second set of limits three years after the interim water treatment plant began operation. On June 11, 2000, the DePue Group finished work at the water treatment plant, as required by Interim Consent Order. The DePue Group has since been operating the water treatment plant.

Several of the Operable Units (OUs) at the site are in the RI/FS phase. During the RI, data is gathered to determine the nature and extent of contamination as well as the risks posed by the contamination. The FS evaluates potential cleanup options. The general status for each OU at the site is described below.


IEPA conducted an RI/FS in the summer of 1997 to determine the nature and extent of the contamination and to evaluate various cleanup alternatives for the South Ditch. An interim remedy was selected in an October 2003 Record of Decision (ROD) to address the unnatural sediments found on the site during previous IEPA investigations. Cleanup objectives included: reducing the potential for floodwater and water discharges to the South Ditch; mitigating acute exposure risk to sensitive ecological and human receptors; preventing onsite trespass; and mobilizing the unnatural sediments. The ROD selected the removal of contaminated sediment with on-site consolidation. The cleanup for OU1 was completed on June 20, 2006. Although the ROD for OU1 was considered an interim ROD, another ROD for OU1 is not anticipated. Rather, the final remedy for OU1 will be selected as part of the OU5 remedy selection process.

The OU1 interim cleanup triggered the requirement for five-year reviews at the site. The First Five-Year Review Report was completed on June 25, 2010. The purpose of a five-year review is to determine whether the remedy at a site is protective of human health and the environment. The subject of the review was the OU1 interim remedial action. The review concluded that the interim remedy at OU1 is protective of human health and the environment in the short term because access to the South Ditch is restricted by a fence and the metals-contaminated sediments that were removed and stored at OU3 in a Corrective Action Management Unit (CAMU) to contain the metals. In order for the remedy at OU1 to be protective in the long term, the remedy selection process for OU5 must be completed and implemented. The Second Five-Year Review Report is due by June 25, 2015.


The cleanup for OU2 is being addressed under Illinois State Landfill Closure regulations. The stack was capped and vegetated. An engineered treatment wetland was constructed adjacent to the landfill as part of the landfill closure. A pilot test to change the vegetative cover from Kentucky 31 fescue (a potential source of fungus to grazing animals) to native prairie habitat is ongoing. In December 2013, the Depue Group installed additional groundwater monitoring wells. IEPA is reviewing a comprehensive hydrogeological study of the phosphogypsum stack and associated groundwater data. 


Much of the plant operations took place at OU3. The zinc smelting process produced slag waste, which was stored on site. Currently, the slag pile is an estimated 65 ft high and one-fourth of a mile long containing various metals and 750,000 tons of zinc. The water treatment plant operated by the DePue Group is also on site. The plant treats water from the lift station for copper, zinc, manganese and low pH. In 2010, a total of 229,000 pounds of zinc, manganese and copper were removed from 24 million gallons of water prior to discharge.

Phase I of the RI/FS at OU3 has been completed. The Phase II RI Report has been finalized, but does not include a risk assessment. IEPA and the DePue Group are developing the work plan for the human health risk assessment.


In December 2013, the DePue Group conducted a Pilot Study to further evaluate off-site soils. During the Pilot Study, the soil at approximately 41 properties throughout the Village was sampled in 6-in increments to a depth of 2 feet. Samples were analyzed for metals that are present on the plant site (OU3), including: antimony, arsenic, barium, cadmium, total chromium, cobalt, copper, iron, lead, manganese, mercury, thallium, and zinc. The results of the Pilot Study were used as the basis for a draft Design Study, which is currently under review. The Design Study is intended to address the investigation, remediation, and restoration of all contaminated properties within OU4. IEPA and the DePue Group are currently working towards resolution of technical issues.


Lake DePue sits to the south of the Village of DePue and receives both contaminated surface water and groundwater discharged from the plant property. RI sampling began in July 2006 and was completed in the fall of 2007. The DePue Lake RI Report was finalized in July 2009. Results indicated that concentrations of metals (zinc, cadmium, copper, lead, etc.) are elevated. The highest concentrations of these metals were located near the South Ditch discharge area and south of Division Street.

The Illinois Department of Natural Resources (IDNR) has issued an advisory to limit consumption of catfish and carp to 1 meal per month of any size, and 6 meals/year of fish less than 24 inches. The fish advisory is the result of PCB contamination, which is not related to the DePue Site. More detailed information is available in IDNR's "Illinois Fishing Information" booklet, which is available at the IDNR website.

IEPA has placed complete copies of the OU5 RI Report, maps, and all data sets in the public repository at the DePue Public Library. IEPA and the Depue Group are working to resolve final issues associated with the human health and ecologial risk assessments. These reports will assess potential risks to humans, plants, and animals from site-related contaminants. Once these reports are final, the next step includes the Feasbility Study, which looks at the ways that a site cleanup can be conducted safely, effectively, and compatibly with state and federal laws.


A five-year review was completed in June 2010 to evaluate the interim remedial action that had been completed at OU1. (See OU1 section above for more information.) A site-wide protectiveness statement could not be made because remedy selection and remedial actions have not been initiated at all operable units of the site. The Second Five-Year Report is due by June 25, 2015.

Success Story

The site was a barren, slag-covered 150+ acres in the middle of town in 1995 when the Interim Consent Order was signed. IEPA considered the barren contaminated soil to represent a potential source of airborne particulate exposure. To assess and reduce this potential, an extensive long-term airborne particulate monitoring program was initiated along with revegetation of the major land mass of the former plant site. No risk or airborne contaminated particulate release has been noted in the sampling program.

The interim water treatment plant, constructed in 1996 and brought fully into compliance with state and federal discharge standards in 2000, has substantially reduced discharges of contaminated water to DePue Lake. This unit removes, for off-site disposal, in excess of 72,000 pounds of zinc, 5,400 pounds of manganese and 2,000 pounds of copper annually.

Community Involvement

The Village of DePue residents formed a Citizens’ Advisory Group (CAG) that meets monthly.

In July 2012, IEPA hosted an informational session at St. Mary’s Church in DePue to hear the site-related concerns of the local Hispanic community and to provide a brief summary of site work. IEPA is exploring ways to have all site-related documents translated into Spanish and available at the information repository or IEPA website.

Congressional Interest

IEPA is committed to providing quarterly updates to elected officials regarding the progress at the site. These reports are routinely posted under the "Legislative Updates" section on IEPA's website for the DePue/New Jersey Zinc/Mobil Chemical Superfund Site.  


Remedial Project Manager, U.S. EPA
colleen moynihan (moynihan.colleen@epa.gov)
(312) 353-8196

Community Involvement Coordinator, U.S. EPA
virginia narsete
(312) 886-4359




Site Profile Information

This profile provides you with information on EPA's cleanup progress at this Superfund site.


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