Skip to main content

Fact Sheet 6

Phase 1 Site-Wide Remedial Investigation

Fact Sheet #6

September 1999

DePue, Illinois

What is a remedial investigation (RI)?

The purposes of an RI include the following:

  • To identify chemicals on the site that may pose a threat to human health or the environment. These chemicals are called contaminants of potential concern (COPC). The questions asked are:
    • Which chemicals are COPC?
    • Where are the chemicals located?

      For example, are the chemicals in the soil, surface water, and /or groundwater? How deep and how widespread are the chemicals?
    • What are the concentrations of the chemicals? (How much?)
  • To identify how the chemicals move in the environment. For example, do the chemicals move through the soil into the groundwater? Do they move with groundwater off the former plant property? Geologic, hydrogeologic and other information is needed to identify chemical movement.
  • To gather other information for human and ecological risk assessments. Phase 1 of the NJZ/MC project will focus on gathering data for a human health risk assessment. (See insert for more information on human health risk assessments.) Later phases will focus on collecting data for an ecological (environmental) risk assessment which includes assessing the possible effect the site might have on plants and animals.

Why is the NJZ/MC remedial investigation being conducted in phases?

Because industries at the site have been in operation since the early 1900s, the sources of possible contamination are not fully understood. For example, there may be areas of old spills or disposal with which we are unfamiliar. We also do not fully understand how and where these chemicals have moved through the air, surface water, groundwater, and soil. A phased approach is necessary so that sample results from Phase 1 can govern the location of Phase 2 samples, etc. This phased approach will be continued until the full extent of contamination is understood

What will Phase 1 accomplish?

Phase 1 data will be a first step in identifying potential contamination sources and direction and rate of groundwater flow. Some known sources such as the zinc slag pile will be investigated in more depth.

Phase 1 will establish procedures to be used in the conduct of the remedial investigation such as quality assurance procedures, health and safety plans, and methods of sampling. These issues, once defined, can be used in subsequent phases of the investigation.

What samples will be collected?

Approximately 500 surface and subsurface soil samples will be collected with use of a drill rig. Approximately 80 groundwater samples from temporary locations will be collected with use of a drill rig or by hand-driven points. Other groundwater samples will be collected from existing monitoring wells or monitoring wells that will be installed during Phase 1.

Additional tests will be conducted on the zinc slag pile to assess the rate, quantity, and quality of water infiltrating through the pile. The analyses will help evaluate which chemicals from the slag pile are dissolved by water and move through the pile into the groundwater.

Who will conduct the work?

Work will be conducted by the DePue Group contractor Golder Associates, Inc. of Redmond, Washington. Work will not begin until the Illinois Environmental Protection Agency (Illinois EPA) approves the DePue Group Phase 1 work plan. The DePue Group work will be overseen by Illinois EPA staff and Illinois EPA's contractor Ecology and Environment of Chicago, Illinois.

Will neighbors living near the site or pedestrians along Marquette be exposed to hazardous levels of chemicals during the investigation?

No. The DePue Group will monitor and take necessary measures to ensure that harmful levels of contaminants do not move past site boundaries.

What are the Phase 1 study boundaries?

This Phase 1 investigation will involve the former plant area and certain areas south of the railroad tracks. See the map on page three with boundaries marked as "Approximate area of historical activity."

What is the time schedule for Phase 1 investigation?

Phase 1 field work will start in September and is scheduled to be completed near the end of the year. After the field work is completed, the samples must be analyzed and the data must be validated. A Phase I Remedial Investigation Data Report will be prepared that will summarize and evaluate the Phase 1 investigation results.

When will Phase 2 begin?

Final plans for Phase 2 will probably not be completed until all the data from Phase 1 are available which is expected to take one to two years


The DePue Group
The DePue Group is a group of past and present owners and operators of the site who have entered into an interim consent order with the state of Illinois to investigate and study remedies for the site and design the chosen remedy. DePue Group members are Horsehead Industries Inc., Mobil Oil Corporation, and Viacom International Inc.
Geologic Studies
Geologic studies at the New Jersey Zinc/Mobil Chemical site include identification of the various types and depths of material at and below the earth's surface. For example, a geologic study would determine the location and depth of materials such as soil, sand, peat, clay, and gravel beneath the surface.
Water beneath the land surface.
Hydrogeologic studies
Hydrogeologic studies encompass the relationship between geologic structures (e.g., soil, sand, peat, and clay) and the movement of water. For example, water will flow more readily through sand than through peat.
Piezometers are similar to monitoring wells and are used to measure groundwater levels. Sometimes the same structures are used for both monitoring wells and piezometers.
A "Superfund" site is a site listed on the National Priorities List which is a U.S. Environmental Protection Agency (USEPA) list of the nation's potentially most serious uncontrolled or abandoned hazardous waste sites.

Human Health Risk Assessments

What is a human health risk assessment?

A human health risk assessment is a process for estimating the degree of risk a site potentially poses to humans. A baseline risk assessment estimates the risk if no action is taken at the site. Risk assessments are based on site information and various assumptions about human exposure following USEPA guidance. Information and assumptions include the following:

  • the types, amounts, and locations of chemicals (data collected during the remedial investigation);
  • the toxicity, of the chemicals;
  • the way the property is used (e.g., residential, industrial, or recreational purposes);
  • who uses the property' (e.g., adult workers, children, and/or the elderly);
  • how people else the property, (e.g., gardening, fishing, swimming, playing, or excavating), and
  • the length of contact (e.g., industrial workers would be exposed only during working hours but if the site were residential, residents could be exposed most of the time).

In order for there to be a risk there must be a completed exposure pathway.

What is a completed exposure pathway?

A completed exposure pathway includes not only a source of contamination, but a point where humans come into contact with a contaminant in such a way that the contaminant can enter a person's body through the skin, through ingestion (eating or drinking) or through breathing. If, for example, a contaminant is in the water but no one drinks, bathes, swims, or fishes in the water, a chemical could be present, but there would be no exposure and therefore no risk to humans.

What is the assumption about future land use for the New Jersey Zinc/Mobil Chemical site?

At the present, the risk assessment for the site (former plant property) will be based on both the conservative scenario of residential use of the property as well as the scenario of continued industrial use of the property. It is unlikely, however, that the land can or will be cleaned up to the level where it would be safe to allow residences as a future use to be built on the current site. Risk assessments for other areas potentially affected by past operations (such as the lake and other offsite property) will be developed in the next phases of the project.

Does the public have any input into the exposure assumptions upon which a risk assessment is based?

The risk assessment will follow the procedures and assumptions set by USEPA and the Illinois EPA. The public will have an opportunity to review the Phase 1 work plan which contains the work plan for the site-wide risk assessment and the exposure assumptions upon which that site?wide risk assessment will be based. Comments about these assumptions will be considered and may be incorporated into the subsequent phases if possible, and if they are not inconsistent with USEPA and Illinois EPA guidelines. The risk assessment work plans for off?site property that may have been affected will be developed in later phases. Comments about assumptions about possible off?site human exposure should be directed toward the Illinois EPA which will consider comments when the off?site risk assessment work plans are developed.

Technical Assistance Grants Available

Citizen groups desiring technical assistance in interpreting data from this investigation may be eligible for a technical assistance grant (TAG). The TAG is a USEPA program which provides up to $50,000 per site to community groups wishing to hire consultants to interpret data generated during a Superfund investigation. Twenty percent of the total funding amount must be provided by the group. These funds may be paid in cash and/or by using in?kind services. TAGs cannot be used to duplicate field or lab work. Their purpose is to give the public a better understanding of existing documents and site activities. Municipalities, other governmental agencies, political subdivisions, potentially responsible parties, academic institutions, and headquarters of public interest groups are not eligible to receive TAGs. However, members of these groups may belong to a community organization requesting a TAG. Further information about TAG is available by contacting: Susan Pastor, TAG Coordinator, USEPA P19J, Office of Public Affairs, 77 West Jackson, Chicago, Illinois 60604, telephone, 1?800/621?8431.

For Additional Information

Repository and future administrative record file location: The project repository, which contains the Phase 1 investigation work plan and other project documents, is located in the Selby Township Library in DePue. The local location for the administrative record file will also be at the Selby Township Library. The administrative record is a file of documents upon which site decisions about remedies will be based.


If you have questions about the project you may contact:

Kurt Neibergall

Office of Community Relations

Illinois EPA

1021 N. Grand Ave. E.

Box 19276

Springfield, Illinois 62794-9276

Phone: (217) 785-3819
Richard Lange

Project Manager

Illinois EPA

1021 N. Grand Ave. E.

Box 19276

Springfield, Illinois 62794-9276

Phone: 815/223-6836

The DePue Group has asked that the name of their contractor be placed on Illinois EPA's fact sheets so the public can contact the DePue Group if they so desire. The DePue Group's contractor is:

James Frank

Frank & Cowles Inc.

Environmental Consultants & Engineers

7226 N. Walnut Street Rd.

Springfield, II 62707


Citizens Advisory Committee Meetings: The public is also invited to attend meetings of the DePue Superfund Citizens Advisory Committee, which consists of DePue residents, governmental staff, and the DePue Group. The advisory committee usually meets the third Wednesday, every other month in the First Congregational Church in DePue at 6:30 p.m.. Contact Dan Blanco, chair, at 815/447?2433 or Virginia Wood at above address for more information about the advisory group.