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Fact Sheet 10d

Source Area 11 Feasibility Study and Proposed Plan

Southeast Rockford Groundwater Contamination Superfund Project

June 2001

Rockford, Illinois

Italicized words are discussed in the "Terms" section at the end of the page.

Purpose Of This Fact Sheet

This fact sheet describes the feasibility study (alternative remedies) and the proposed plan for Source Area 11 of the Southeast Rockford Groundwater Contamination Superfund project. Fact sheets describing the alternatives and proposed plans for the other three major source areas are available from information sources listed in the back of this fact sheet. A groundwater remedy, focusing on all the project area groundwater predicted to be affected by contamination in the next 65 years, was chosen in 1995. The groundwater remedy is described below.

What is Source Area 11?

Source Area 11 is an industrial/commercial area in southeast Rockford shown on the map below. When the project began, the sources of groundwater contamination in southeast Rockford were unknown. In the Phase I project investigation, the Illinois Environmental Protection Agency (Illinois EPA) identified 14 study areas as possible sources of contamination. After several years of study, the Illinois EPA identified four of these study areas (Areas 4, 7, 11 and 11) as the major sources of groundwater contamination in this project. These study areas, therefore, were renamed Source Areas 4, 7, 9/10 and 11.

What are the main contaminants at Source Area 11?

The contaminants detected at Area 11 are mainly chemicals found in oil and gasoline with lesser amounts of industrial solvents. Free product was detected floating on the water table between 39 and 45 feet below ground surface. Most of the Area 11 chemicals are volatile organic compounds ( VOCs). ?Organic? means the chemicals contain carbon and ?volatile? means they vaporize (evaporate) easily. The enclosed "Remedial Investigation" fact sheet has more information about Area 11 contamination.

What is the Source Area 11 proposed plan?

For each source area, including Area 11, the Illinois EPA and United States Environmental Protection Agency ( U.S.EPA) propose one remedy for the contaminated soil and a second remedy for the leachate. The agencies studied three alternatives for the soil remedy in Source Area 11 (Table 1). Of these alternatives, the agencies propose soil vapor extraction (SCS-11C). The agencies studied and propose one remedy (Table 2) for the leachate. The leachate remedy is called the "No action" alternative but includes groundwater monitoring and restrictions on use of the property. The public is invited to comment on all the alternatives.

Table 1


Source Area 11
Alternative Summary description Time* Cost
SCS-11A No Action No action. The longest of soil alternatives None
SCS-11BLimited Action Institutional controls. Institutional controls would be used to restrict use or access to the property until remediation goals are met. Same as SCS-11A $28,000

SCS-11C Soil Vapor Extraction and Catalytic Oxidation

Institutional controls. Same as described in SCS-11B.

A series of soil vapor extraction ( SVE) wells connected by underground piping would be installed in the area above the water table. Since the contaminants are VOCs and therefore volatize easily, the vapor phase of the contaminants collect in the underground air pockets above the water table. A vacuum applied to underground wells and piping would collect the vapors from these air pockets. When they are collected, more vapors from the contaminants would move into the underground air pockets thus reducing the amount of contaminants in the soil and groundwater.

Catalytic oxidation unit. The vapor from the soil vapor extraction system would be directed to a catalytic oxidation unit. This unit would break the VOCs into harmless compounds such as water and carbon dioxide plus hydrochloric acid. A scrubber would treat the hydrochloric acid, forming water and salts, before discharging the vapors into the atmosphere. The scrubberwater, pH adjusted to normal, would be discharged to a nearby drainage ditch.

Air monitoring. A proof of performance test would be conducted before standard operations, and air emissions would be monitored during standard operations to ensure all air quality standards are met.

Possibly air sparging. If analysis indicates that contaminant concentrations are not decreasing sufficiently, air sparging wells may be added. In air sparging, a pump on wells injects air into the soil and leachate. The additional air would increase the volatilization rate of the contaminants thus speeding up their removal from the soil and groundwater.
Between two and five years of treatment are anticipated depending on soil conditions under the buildings. $3,185,500
* Time to meet remediation goals.

The Illinois EPA and U.S.EPA propose this alternative for the Source Area 11 soil remedy.

What is leachate? Leachate is source material that has migrated, or could potentially migrate from a source area into groundwater in the vicinity of the four primary source areas. For purposes of the Proposed Plan, leachate includes source materials at Areas 4, 7, 9/10, and 11 that are sources of contamination in the groundwater at those areas which must be contained or controlled to protect human health and the environment.

What is the groundwater management zone ( GMZ)? The GMZ is the area of contaminated groundwater that will be treated by the Area 11 leachate remedy. The map above shows the GMZ boundary. The groundwater beyond the GMZ will be treated by natural attenuation as specified in the groundwater remedy described below.

What is the purpose of the Area 11 remedy? The remedy has several purposes including:

  • to stop ongoing contamination of the groundwater by Area 11 waste, thus protecting the water resource for further generations;

  • to reduce the potential for people to come into direct contact with free product and contaminated soil beneath the ground surfaces;

  • to comply with the 1995 Record of Decision for the project that required groundwater contamination sources be controlled; and

  • to ensure that VOCs in soil gas do not move into basements of nearby buildings.
Table 2


Source Area 11
Alternative Summary Description Cost

SCL-11A No Action

Institutional controls. Institutional controls would be used to restrict the use of groundwater in Area 11 until soil remediation goals are met.

Groundwater/ leachate monitoring. Four additional monitoring wells would be installed and monitored in addition to the two existing monitoring wells. (One existing well is not shown on the map above because it is farther east than the map area covers.) The wells would be tested quarterly for VOCs for two years followed by a semiannual program of testing for years three through 30.

Natural attenuation. Calculations predict that natural attenuation, a naturally occurring process, causes contaminants in groundwater to be reduced to concentrations that meet the remediation goalsby the time the groundwater reaches the GMZ boundary.
The Illinois EPA and U.S.EPA propose this alternative for the Source Area 11 leachate remedy.

How are remedies evaluated?

The federal Superfund law specifies the following nine criteria for evaluation of remedies. They are (1) overall protection of human health and the environment, (2) compliance with relevant state and federal law, (3) long-term effectiveness and permanence, (4) reduction of toxicity, mobility or volume of contaminants through treatment, (5) short-term effectiveness, (6) implementability, (7) cost, (8) state acceptance and (9) community acceptance.

Why do the Illinois EPA and the U.S.EPA prefer alternatives SCS-11C and SCL-11A for Area 11?

Soil vapor extraction ( SVE) and groundwater/ leachate monitoring are preferred for the following reasons: (1) SVE substantially reduces risks by treating the contaminants in the soil, thus protecting human health and the groundwater over the long term. (2) The alternatives will comply with all federal and state laws. (3) They reduce toxicity. (4) They are cost effective and implementable.

What are the Area 11 remediation (remedy) goals?

The remediation goals for Area 11 are set primarily for volatile organic compounds ( VOCs), because VOCs are found in the groundwater. The soil goal is based on state guidelines (called the Tiered Approach to Cleanup Objectives or TACO) for residential use and groundwater protection.

The goals for leachate (Area 11 groundwater) are the federal drinking water standards at the GMZ boundary. Semi-volatiles (such as chemicals found in oil and asphalt) were also detected in Area 11. The Illinois EPA will take more samples to see if they are contaminants of concern or if they are in concentrations that are commonly found in urban environments.

Is my water safe to drink?

Your water is safe to drink if you are connected to the Rockford Public Water Supply. The City of Rockford routinely tests its supply for possible contaminants. Water that fails to meet U.S.EPA drinking water standards is not distributed to the public.

Next Steps

How is the final remedy decision made?

After the public comment period has ended, the Illinois EPA and U.S.EPA will carefully consider all written comments received during the entire comment period plus the oral comments made at the hearing. Based on consideration of these comments, the Illinois EPA and U.S.EPA will make a final decision on the Area 11 remedy as well as the remedies for the other three major source areas. The Illinois EPA will notify the public of the final decision in a Record of Decision. The Illinois EPA will also summarize the public comments received and the agencies' responses to these comments in a responsiveness summary.

Who will pay for the remedy?

The Illinois EPA and U.S.EPA have been unable to identify responsible parties able to pay for the Area 11 remedy. As a result, the chosen Area 11 remedy will be constructed and operated with funds from the federal Superfundand the Illinois Hazardous Waste Fund.

When will the remedy be constructed?

The Illinois EPA and the U.S.EPA plan to begin designing the remedy this summer or fall winter and begin construction in late 2001 or early 2002.

The Groundwater Remedy

In 1995, after carefully considering public comment, the Illinois EPA and the U.S.EPA chose a remedy for the area-wide groundwater ( groundwater outside the groundwater management zones of the four major source areas). The City of Rockford (with U.S.EPA oversight) began implementing the groundwater remedy in 1998. The groundwater remedy includes:

  • Rockford Public Water Supply connection for all properties with private drinking water that are in an area predicted to be affected by the contaminated groundwater within the next 70 years (65 years from present).

  • Continued treatment of Rockford Municipal Well #35 with granular activated carbon.

  • Monitoring of the contaminated groundwater plume and, if necessary, connecting additional properties to the Rockford Public Water Supply, if they are threatened by contamination.

  • Treatment of the groundwater by natural attenuation. Natural attenuation is a process by which contaminants are broken down by naturally occurring microbes in the soil or by other natural processes.

  • Control of the four major source areas. This fact sheet describes possible remedies and the proposed plan to control source Area 11. Fact sheets describing proposed remedies for the other three source areas can be obtained from Illinois EPA staff or other sources listed at the end of this fact sheet.


Air stripping.
A method of removing volatile chemicals (chemicals that vaporize easily) from water. Often, air stripping consists of letting water fall over a distance in a confined area, exposing the volatile chemicals to air and thus allowing them to evaporate. Usually the vapors from an air stripping system are collected and treated before being released into the atmosphere.

Air sparging.
A method of removing volatile organic compounds (chemicals that vaporize easily) from groundwater. During the process, air is forced into groundwater. Volatile chemicals then vaporize or move into the air bubbles. The air bubbles move with the chemical up to the air pockets in the soil above the groundwater (water table). Usually air sparging is accompanied by a system such as soil vapor extraction where the vapors (with the chemicals) are collected and treated.

Catalytic oxidation.
A method of treating volatile organic compound (VOC) vapors so they are broken down into harmless chemicals. See fact sheets on treatment units for more information on catalytic oxidation.

The direction groundwater flows. Water flows "downhill" or downgradient.

Free product.
Chemicals present in high enough concentrations that they are undissolved in water. See NAPL.

Water beneath the ground surface.

GMZ (groundwater management zone).
An area of contaminated groundwater that will be treated by the Area 4 leachate remedy. The goal of the Area 4 leachate remedy will be met when groundwater at the GMZ boundary meets federal drinking water standards. The groundwater outside the GMZ will be treated by natural attenuation as described in "The groundwater Remedy" above. The map on above shows the boundary of the GMZ for Area 4.

Institutional controls.
An administrative or legal constraint that limits land or resource use. Controls could include zoning restrictions, city ordinances, easements, covenants, consent decrees, notices on deeds, or state registries.

Source material that has migrated, or could potentially migrate from a source area into groundwater in the vicinity of the four primary source areas. For purposes of the Proposed Plan, leachate includes source materials at Areas 4, 7, 9/10, and 11 that are sources of contamination in the groundwater at those areas which must be contained or controlled to protect human health and the environment.

LTTD (low temperature thermal desorption).
A unit that heats soil to a point where volatile organic compounds such as found in Area 4 will vaporize (evaporate). Vapors would be treated before being released to the atmosphere. See fact sheet on treatment units for more information on low temperature thermal desorption.

NAPL (non-aqueous phase liquid).
Free product. When a contaminant is present in high enough concentrations in groundwater, it does not dissolve in the water. Rather, if it is lighter than water (like oil), it will float on top of the water. If it is heavier than water, it will sink through the water until it comes to a barrier such as rock or clay.

Natural attenuation.
A natural process. Either naturally occurring microbes in the soil break down the contaminants into harmless components or the contaminants become adsorbed (attached) to soil particles preventing them from moving into the groundwater. Groundwater beyond the GMZ boundary will be treated by natural attenuation alone and will meet drinking water standards in an estimated 200 years.

Reactive barrier wall.
An underground trench filled with a reactive substance such as iron filings. As groundwater moves through the wall, contaminants such as VOCs react with the iron to form non-toxic compounds. During the wall construction, two jetting wells would be installed within the iron filings. These wells would allow for rejuvenation (renewal) of the iron media by flushing out solids or biological growth that could clog the reactive wall.

Remediation goals.
Cleanup objectives. Remediation goals determine the amount of contamination that must be removed before the remedy is considered complete. For example, the leachate remediation goal at the groundwater management zone boundary for the chemical 1,1,1-trichloroethane is 200 parts per billion. (Two hundred parts per billion is the federal drinking water standard.) The remedy for leachate will not be considered complete until the groundwater is cleaned to the point where no more than 200 parts per billion 1,1,1-trichloroethane remain at the GMZ boundary.

An air pollution control device that removes compounds with a low pH (such as hydrochloric acid) from gas before the gas is released into the atmosphere. Some scrubbers use dry materials such as calcium carbonate while others use water to remove acid gases.

SVE (soil vapor extraction).
A method of removing volatile organic compounds from contaminated soil and groundwater. Soil vapor refers to the air in spaces between soil particles beneath the ground. These spaces are called soil pores. Since the nature of VOCs is that they vaporize easily, they will vaporize from contaminated groundwater or soil into the soil pores. In SVE, these vapors are sucked out of the soil pores and usually pumped to the surface. The vapors are directed into a liquid vapor separator. The liquid is collected and sent off-site for proper treatment/disposal. The vapors are usually treated and released into the atmosphere. When the VOC vapors are removed from the soil pores, more VOCs vaporize from the contaminated soil or groundwater into the pores. These vapors, in turn, are extracted by the SVE system thus gradually reducing the amount of VOC contamination in the soil or groundwater.

The common name given to sites on the National Priorities List (NPL). The NPL is a list of the nation's most serious hazardous waste sites that are eligible for investigation and, if necessary, a remedy under the federal Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), sometimes called the Superfund law. The Southeast Rockford groundwater Contamination project was placed on the NPL in 1989.

The United States Environmental Protection Agency.

VOCs (volatile organic compounds).
Volatile means the compounds vaporize (evaporate) readily under normal conditions. The compounds are called organic because they contain carbon.

For More Information:

Contacts: For more information about the project including fact sheets on the remedial investigation results, feasibility studies and proposed plans for each of the four major source areas, you may contact the Illinois EPA staff listed below:

Tammy Mitchell

Community Relations Coord.

Illinois EPA

1021 N. Grand Ave. E.

Box 19276

Springfield, Illinois 62794-9276

Phone: (217) 524-2292
Thomas Williams

Project Manager

Illinois EPA

1021 N. Grand Ave. E.

Box 19276

Springfield, Illinois 62794-9276

Phone: (815) 223-1714

Repositories: Full reports for the project may be reviewed at the following locations.

Rock River Branch

Rockford Public Library

3128 S. 11 th Street

Rockford, IL 61109


(Call for hours)
Ken-Rock Community Center

3218 S. 11th Street

Rockford, IL 61109


(Call for hours)

Administrative record file: The administrative record file is located at the Illinois EPA headquarters in Springfield, Illinois. Call 217-782-9878 for an appointment. The administrative record file will also be located on microfiche at the Main Branch of the Rockford Public Library at 215 N. Wyman in Rockford.