Fact Sheet 4

DePue, Illinois

Treatment Capacity

Expected Averate Treatment Rate:

50 gallons/minute

(100 gallons/day)

Maximum Treatment Capacity:

100 gallons/minute

(144,000 gallons/day)

This fact sheet describes the interim water treatment system that the DePue Group ( Horsehead Resources Development Co., Inc., Mobil Oil Corporation, and Viacom International Inc.,) is constructing to reduce the levels of metals in groundwater (water beneath ground surface) and surface water discharging into DePue Lake. These metals have accumulated in the soil of the former New Jersey Zinc/Mobil Chemical site from years of zinc smelting and other industrial processes. The metals are either leached (dissolved) or washed into the water on particles of metal-bearing soil. Occasionally, some of this water has flowed over the Marquette Street sidewalk.

1. pipes that collect the water,
2. a lift (pump) station south of Marquette Street which pumps the water to,
3. the treatment system located in the former New Jersey Zinc building.

The interim water treatment plant and the lift station are being constructed under Illinois Environmental Protection Agency (Illinois EPA) permits. The system is scheduled to begin operation in Spring 1997.

Sources of Water

• Groundwater south of Marquette Street.
• Groundwater north of Marquette Street, the source of water that occasionally flowed over the sidewalk.
• Surface water and groundwater from the ditch that runs on the northeast side fo the slag pile.

Comparison of Contaminants Before and After Interim Treatment

1. The three sources were sampled on January 29, 1996. The number in this column represents the highest concentration of the three sources on that day.
2. These are interim treatment requirements allowed in the interim consent order. Three years after the treatment system is in place, the required concentrations Will take into account the Illinois Water Quality Standards.
3. ppm = parts per million
4. pH cannot be averaged Each sample must toll within the range of 6-9.

Summary of the Interim Water Treatment Process

The water then is pumped into the clarifies where solids containing the metals settle out.

The liquids are pumped to a neutralizer tank where a small amount of sulfuric acid is added to bring the pH down to a range of 6?9 (which is more neutral) before the treated water is discharged to DePue Lake. Some sludge is recycled back to the reaction tank, and the remaining sludge is pumped to the sludge tank.

Sludge is pumped from the sludge tank to a filter press which squeezes as much water as possible from the sludge. This water is recycled back to the reaction tank. The solids from the filter press are pumped to a solids blender where they may be mixed with kiln dust, if needed. The dust stabilizes the metals so the metals will not leach out. (Leaching occurs when water washes contaminants out of a solid or near solid substance.) If the mixture meets all criteria, it can be sent to a special waste landfill designed for non-hazardous waste from certain industrial processes. The DePue Group also is looking at possible methods for using the sludge for beneficial purposes.

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.

Contacts:

If you have questions about the project you may contact:

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: