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Fact Sheet 13

Fact Sheet #13 August 2010

Bureau County, DePue, Illinois


This fact sheet provides an update on the work accomplished at the New Jersey Zinc/Mobil Chemical Superfund site (Site) in the Village of DePue over the past year for Operable Units (OU) 2, 3 and 5. The Illinois Environmental Protection Agency (Illinois EPA) and the U.S. EPA are also conducting the required five-year review of the on-going long-term remediation and monitoring of OU1, the South Ditch. This review was expected to be completed during May 2010 and be available shortly thereafter in the repository at the DePue Public Library.


The former New Jersey Zinc/ Mobil Chemical site is located in the Village of DePue in Bureau County. The former zinc smelter plant began in the early 1900s with operations that included zinc smelting, and eventually sulfuric acid production, diammonium phosphate fertilizer production, lithopone paint pigment production and zinc dust production.

Many of the plant operations took place before most environmental regulations existed; however, contaminants were released into the air, water and land during the time it operated, and some of these contaminants remain. On-site and off-site sampling of surface water and soil sediments by the Illinois EPA indicated elevated levels of various metals. Due to the potential risk related to the elevated levels, a notice was sent to all potentially responsible parties (PRPs) identifying actions to remedy the site. These actions included an investigation of the extent and types of contamination and a study of appropriate remedial actions. The DePue Group is actively engaged in the implementation of these studies and remedial actions, as further detailed in this fact sheet. Descriptions of remedies and actions taken earlier can be found at etc.

Because of the complexity of the site, the Illinois EPA organized the site into five Operable Units (OU’s):

  1. OU1 – The South Ditch Sediment
  2. OU2 – The Phosphogypsum Stack
  3. OU3 – The Former Plant Site Area (FPSA)
  4. OU4 – Off-Site Soils
  5. OU5 – DePue Lake Sediments and Floodplain

OU2: Phosphogypsum Stack

  • In the fall of 2009 and early summer of 2010, 14 additional monitoring wells were installed to better understand the groundwater flow and potential off-site groundwater contamination.
  • In April of 2010, a prescriptive burn was performed at the phosphogypsum stack to enhance the growth of the native prairie habitat. This type of burn is conducted every two or three years to control weeds and for thatch removal to promote healthier growth. The DePue Group retained a specialty contractor to manage the burn with assistance from the DePue Volunteer Fire Department.
  • The native shrub hedge around the wetland was planted in the fall of 2009. This hedge replaces the more typical chain-link fence and works more cohesively with the native habitat vegetative cover being pilot tested and planned for use in ultimate closure of the phosphogypsum stack.

OU3: Former Plant Site

  • In the spring of 2010 work was conducted in the railroad right-of-way to study any past discharge from the former Lithopone Plant, which was located in the southwest corner of the former plant site. In the earlier days of operation of the plant, this site had an open ditch that was later converted into a 24-inch tile pipeline. Five test pits were dug to gain access to the base of the former ditch and underneath the pipe on the north side of the railroad track from East Street west to Sherman Street.
  • An additional 14 wells in eight locations were installed by the DePue Group between the former plant site and DePue Lake. These wells will primarily be located on city-owned property adjacent to streets and sidewalks. These wells will be used to determine the extent of any potential groundwater contamination.
  • During 2009, the on-site interim water treatment plant operated by the DePue Group processed approximately 24 million gallons of groundwater and removed over 229 thousand pounds of zinc, copper and manganese.

OU4: Off-Site Soils

  • The Removal Action Limit Sampling Report has been finalized and a publicly releasable edition will be prepared later this summer. This fall we anticipate finalizing the Background Sampling Report and complete the Remedial Investigation Work Plan near the end of the year.

OU5: DePue Lake

  • The Risk Assessment portion of the investigation of DePue Lake is currently underway and is on schedule to be completed by late this year. The Risk Assessment is a detailed report evaluating the potential of contaminants found in the lake sediments and flood plain soils to cause adverse effects to people and wildlife.
  • Sampling scheduled to take place during the summer of this year will fill the data gaps identified in the Lake Remedial Investigation. Sample collection has been delayed a number of times due to high water levels in DePue Lake restricting access to areas of the flood plain. These samples will be needed for the Feasibility Study scheduled to begin this winter following the completion of the DePue Lake Risk Assessment.

For more information, you may contact:

Jay A. Timm

Community Relations Coord.

Office of Community Relations

Illinois EPA

(217) 557-4972
Rich Lange

Project Manager

Illinois EPA

(815) 447-2125