New Jersey Zinc/Mobil Chemical

New Jersey Zinc/Mobil Chemical Superfund Site

Progress Report
July 2006

DePue, Illinois

This fact sheet is a project update about work accomplished at the New Jersey Zinc/Mobil Chemical Superfund site (“Site”) in the Village of DePue during the year 2005, and projected activities for 2006. Significant progress was made in several of the Operable Units (OUs), or areas of concern associated with the Site. In 1995, the State of Illinois and the potentially responsible parties (PRPs)¹ entered into an Interim Consent Order to conduct Remedial Investigation/Feasibility Study activities, including investigation and remediation of the following Operable Units: OU1, South Ditch Sediment; OU2, Phosphogypsum Stack; OU3, Former Plant Site; OU4, Off-Site Soil; and OU5, DePue Lake and Floodplain. During 2005, the following activities were completed by the PRPs with oversight by the Illinois EPA.

OU1, South Ditch Sediment

• A Remedial Design Work Plan was completed by the DePue Group and approved by Illinois EPA in January 2005.
• Excavation of 4,026 cubic yards of South Ditch sediment, with treatment and dewatering of the sediment and placement in a Corrective Action Management Unit constructed on the former plant site, was completed in November 2005.
• The South Ditch work area was restored in November 2005.

OU2, Phosphogypsum Stack

• The DePue Group prepared Design and Construction Drawings and Bid Sheets for Closure of the fourth and final pond in the Southeast Quadrant of the Phosphogypsum Stack.
• The Center-Pivot Spray Irrigation System pumped 47 million gallons from the Clear Water Pond.
• Phosphogypsum sediments and natural soils were excavated and hauled from the Return Water Channel area and were incorporated into the phosphogypsum stack. Natural soils were used as final cover for the stack and to rough-grade the 6.4-acre Return Water Channel area. A free water surface treatment wetland is proposed to be constructed in the Return Water Channel of the DePue Phosphogypsum Stack Clearwater Pond.
• The DePue Group began Treatment Wetland Design and submitted a Phosphogypsum Stack Vegetation Management Plan to Illinois EPA for review and approval.
• As of December 2005, the draft Phase II Hydrogeologic Investigation report and Phase III Work Plan are considered 99% complete.
• Grading of the Southeast Quadrant was finished by November, a final soil cover was applied, and the area was seeded with winter wheat. Erosion control measures were applied to the side slopes of the Return Water Channel area, including seeding with winter wheat and placement of erosion control matting along the side slopes of the proposed treatment wetland area.

OU3, Former Plant Site

The DePue Group constructed a Corrective Action Management Unit on the former plant site as a repository for the unnatural sediment removed from the South Ditch.

Interim Water Treatment Plant Operations: During 2005, 6,179,626 gallons of groundwater and surface water were treated, with 101,901 pounds of zinc, 7,910 pounds of manganese, and 5,558 pounds of copper removed. Prior to construction and operation of the Interim Water Treatment Plant in 1997, these metals would have been discharged into DePue Lake.

The Illinois EPA approved placement of sludge from the Interim Water Treatment Plant into the Corrective Action Management Unit during the South Ditch work. A large portion of the solids generated by the Interim Water Treatment Plant during the South Ditch work came from the South Ditch activity.

A Revised Phase I Remedial Investigation Report and a Phase II Remedial Investigation Work Plan were being prepared by the DePue Group.

OU4, Off-Site Soil

The results of historical soil sampling by the Illinois Department of Public Health indicated that elevated levels of metals may exist in residential and non-residential soils around the DePue Site. Given the existing data, additional investigations were conducted in the village by the DePue Group to determine the nature and extent of potential off-site soil impacts; to determine whether waste from the plant site had been used for fill or other purposes in residential yards or other off-site properties; and to begin collection of information for a human health and ecological risk assessment.

• The DePue Group submitted a revised Off-Site Soils Phase I Remedial Investigation Work Plan and supporting documents, including a Quality Assurance Project Plan, Field Sampling Plan, and Health and Safety Plan. These documents were approved by Illinois EPA in May 2005.
• A public availability session was held by Illinois EPA, interviews of village residents were conducted, and first-round sampling and assessment of the 17 properties of specific interest from past Illinois Department of Public Health sampling was completed.
• A comprehensive village-wide walking tour was conducted by the DePue Group and the Illinois EPA to locate visually identifiable materials historically taken from the former plant site and used as fill within the DePue area.
• In October, the results of the sampling and assessment were submitted to the Illinois EPA by the DePue Group in an Off-Site Soil Removal Action Limit Assessment Report. The Removal Action Assessment has found significantly lower metal concentrations than Illinois Department of Public Health, and no immediate health threats.

OU5, DePue Lake and Floodplain

The DePue Lake Remedial Investigation Work Plan, including an Ecological and Human Health Risk Assessment Work Plan, a Quality Assurance Project Plan, Field Sampling Plan, and Health and Safety Plan, was submitted to the Illinois EPA in February 2005. As of December 2005, the DePue Group has continued to work with Illinois EPA on a response to comments and preparation of Work Plan revisions.

Projections for 2006

During 2006, a significant number of activities are planned for each of the operable units at the New Jersey Zinc/Mobil Chemical site.

• Fieldwork for the DePue Lake Remedial Investigation will be initiated, including sampling and analysis of sediment to depths up to 15 feet below current lake bottom, surface water, living plants, animals, and water species, mapping of spring water flows into the lake, performance of sedimentation studies, and floodplain and background lake investigations.
• The initial Removal Action Assessment has been completed and the Off-Site Soils Remedial Investigation will be started. As part of the Off-Site Remedial Investigation, a limited number of properties investigated as part of the Removal Action Limit Assessment may be further examined.
• The DePue Group expects to submit the Revised Phase I Report for the Former Plant Site Remedial Investigation to Illinois EPA in May 2006, and the Phase II Remedial Investigation Work Plan in June 2006. Phase II Remedial Investigation activities on the Plant Site are anticipated to begin later in 2006.
• The Phosphogypsum Stack will be revegetated, with a large-scale pilot test of native prairie grass establishment.
• Construction of the Phosphogypsum Stack Treatment Wetland is scheduled for completion.

Although much was accomplished in 2005, the Illinois EPA and the DePue Group are committed to progressing with the investigations and environmental studies needed in each of the Operable Units of the New Jersey Zinc/Mobil Chemical site. With the schedule planned for 2006, and the continued cooperation of other state agencies and the Village of DePue, further progress is anticipated during the upcoming year.