Limited excavation of contaminated soil—Source Area 4

Southeast Rockford Groundwater Contamination Superfund Site

From Illinois EPA fact sheet

In September, the Illinois Environmental Protection Agency (Illinois EPA) excavated a small quantity of contaminated soil at the former Swebco facility at the corner of Marshall and Alton streets in southeast Rockford.

Why is the Illinois EPA excavating this soil?

The Illinois EPA and U.S. Environmental Protection Agency (U.S. EPA) have signed a record of decision to remedy contaminants found in what is called Source Area 4. (See accompanying article.) To prepare for the construction of that remedy, the Illinois EPA conducted additional investigations in the area. Investigation results showed free product and contaminated soil near the building and closer to the surface than expected. Since the contamination is so close to the surface, the Illinois EPA and U.S. EPA decided that removing these soils and free product is necessary to prevent human exposure. Also, removing this quantity of contaminated soil and free product will have the immediate effect of reducing movement of contaminants off site in groundwater. The remedy of the remaining contamination is planned for 2006.

Will excavation release harmful levels of contaminants into the air?

No. The contaminants are industrial solvents in a category called volatile organic compounds (VOCs), which means that they do evaporate readily at normal indoor/outdoor temperatures. To protect the public and the workers, the Agency and its contractor will monitor the air continuously. Workers may wear respirators as a safety precaution to prevent possible exposure to unsafe levels of contaminants that may be present at the excavation hole. If total concentrations at the site boundary reach one part per million above background of total VOCs, the Illinois EPA will take corrective action to contain any emissions and possibly shut down the operation. One part per million total VOCs is below the level that would be harmful to humans.

Will there be odors?

There may be odors. Some of the chemicals found at this site give off significant odors at levels that are not harmful to human health. Smelling chemicals, in this case, does not necessarily mean that harmful levels of chemicals are in the air. The Agency’s continuous air monitoring will ensure that harmful levels of contaminants are not leaving the site.

If odors become a problem, the Agency has authorized the use of foam in the excavation hole and in the roll-off box where the excavated soil will be placed. This foam is designed to greatly reduce odors. Illinois EPA staff will be talking to nearby residents about steps that can be taken if odors become offensive beyond the boundaries of the excavation. The roll-off boxes of excavated soil will be removed at the end of each workday and properly disposed of offsite.

What is going to be done with this contaminated soil and free product?

The contaminated soil and free product will be disposed of in an appropriate offsite landfill or treatment facility.

How long will excavation take?

Excavation of this small quantity of soil and free product was expected to take two to three days.

Work planned for November

In November, the Illinois EPA will conduct more work at the site in preparation for implementation of the final remedy in 2006. November work will include soil borings to determine the amount of soil that must be excavated and treated in 2006. Also, a temporary system will be installed on site to determine the amount of groundwater that will have to be pumped and the rate at which the groundwater will have to be treated.

What is the final remedy for Source Area 4?

The 2002 record of decision for Source Area 4 requires one remedy for soil and one remedy for leachate. The soil remedy includes institutional controls, soil excavation and on-site treatment of contaminated soils by low temperature thermal desorption. The leachate remedy is institutional controls plus leachates containment and treatment. The construction of this remedy is planned for 2006. The Illinois EPA will be distributing additional information about this action closer to the time of construction.

From the Oct. 5-11, 2005, issue

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