Editor’s note: Unless attributed otherwise, the information contained in this article was derived from the seven-volume Chemplex Superfund Draft Permit Administrative Record issued in June 2007. The record is available for review at the Clinton Public Library.

This information is being provided as residents prepare for a July 10 meeting at the Camanche Fire Station, where officials will answer questions from residents from 6:30 to 8:30 p.m. Tomorrow’s story will focus on remediation at the site, while Saturday’s story will be about the future of the area.

CLINTON — The Chemplex Superfund site is located five miles west of Clinton, south of U.S. 30 and west of U.S. 67.

The Chemplex polyethylene manufacturing plant was constructed in 1967 and began operation in 1968, manufacturing both high-density and low-density polyethylene. The site encompasses approximately 700-acres and the plant includes several ethylene production areas, water and wastewater treatment plants, a landfill and other chemical and product storage tanks and loading areas.

For discussion purposes, the site is divided into two regions, named “West” and “East” regions.

According to a June 2007 EPA Fact Sheet, American Chemical Co. and Getty Chemical Co. operated the plant until 1984 and are the current owners of the seven-acre landfill area on the western portion of the site.

The fact sheet states that Equistar Chemicals currently operates the polyethylene facilities and owns the plant property, excluding the landfill area owned by ACC/GCC.

The West region of the site includes the seven-acre landfill

that was used for the disposal of various materials, including demolition debris and water treatment sludges. From approximately 1968 to 1978, tetrachloroethylene, also known as perchloroethylene or PCE, was used at the plant to occassionally clean clogged piping.

Spent PCE was disposed of in the landfill, leading to groundwater and soil contamination at the site. The EPA Five-Year Review report of the site, released in June 2004, stated that other plant waste materials disposed of in the landfill included black oily sludge, scrap polyethylene, construction debris, carbonate sludge and spent solvents.

The Chemplex site was identified as a potentially uncontrolled hazardous waste site and proposed for the National Priorities List, a list of the worst hazardous waste sites as identified by Superfund, in 1984.

According to a 1984 EPA NPL site narrative, wastes generated by Chemplex included peroxides, mineral spirits, vinyl acetate and various organic hazardous substances such as styrene, benzene, toluene and polyaromatic hydrocarbons.

“Unknown quantities of these wastes were disposed of in an unlined landfill on the site, which has been covered and is no longer used,” the document states. “Wastewater containing some of these constituents was also stored in a two-acre lined impoundment on the site. During dredging of the sediments from the bottom of the impoundment, the liner was ruptured, releasing hazardous substances.”

According to the June 2004 EPA Five Year Review, the lined impoundment was a polishing basin used as a process water-settling pond. In 1974, the basin was dredged and the clay liner was damaged causing contaminants to leach into the underlying soil. The damage was discovered in 1982 when the basin was drained. It was rebuilt with a new liner and a leachate collection system was installed.

The 1994 NPL site narrative asserts the EPA proposed dropping Chemplex Co. from the proposed NPL in 1988 because it was subject to the corrective action authorities of the Resource Conservation and Recovery Act and the potentially responsible parties agreed to clean up the site effectively and construct a system to pump and treat contaminated ground water. The site was removed from the NPL in 1991.

Investigations performed in the 1980s and 1990s showed that groundwater at the site was impacted by PCE and polynuclear aromatic hydrocarbons.

A 1991 Health Assessment Technical Report stated, “On-site soils and on-site and off-site groundwater are contaminated with considerable amounts of volatile organic compounds, i.e. benzene, 1,1-dichloroethylene, 1,2-dichloroethylene, trichloroethylene, xylene, toluene, ethylbenzene, etc., and polycyclic aromatic hydrocarbons at levels of public health concern. The populations at risk of exposure include employees at the facility, remedial and construction workers, and residents in close proximity to the site. There are approximately 475 employees at the facility. Ten residences having an estimated population of 25 persons are located at various locations within a half-mile radius of the site. Area residents utilize private wells to obtain groundwater from the shallow bedrock aquifer for domestic and agricultural purposes. Potential human exposure pathways include ingestion, inhalation, and dermal contact with contaminated on-site soil and groundwater. The site poses a potential risk to human health because of possible exposures to contaminants at concentrations that may result in adverse health effects.”

Currently, approximately two dozen residences in the area are downgradient of the East and West regions. Each residence has a private water supply well and the depth of these wells is estimated to vary between 40 to 150 feet below ground surface.

The EPA has been working with the Iowa Department of Natural Resources and Citigroup and ChevronTexaco, or ACC/GCC, to clean up the site. The initial cleanup plan was approved in 1989. A EPA Fact Sheet released in May of 2006 states the EPA divided cleanup activities at the Site into two phases, called operable units. The site was managed in two units, one addressing groundwater contamination through an extraction and treatment remedy that has been in operation since May 1994. The second unit addressed contaminated soil and waste at the site by capping and soil vapor extraction.

That remedy began in 1998 and ceased operation in 2003 because it met the shutoff criteria established. Through 2003, over 23,000 pounds of VOCs had been recovered from the site via groundwater extraction and treatment.

This Week's Circulars