Fact Sheet 10a
Source Area 4 Feasibility Study and Proposed Plan
Southeast Rockford Groundwater Contamination Superfund Project
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 4 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 the Illinois EPA staff and other sources listed at the end 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 4
Source Area 4 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, 9/10 and 11) as the major sources of groundwater contamination. These study areas, therefore, were renamed Source Areas 4, 7, 9/10 and 11.
What is the main contaminant at Source Area 4
The main contaminant at Area 4 is 1,1,1-trichloroethane (TCA) which is an industrial solvent used for such things as degreasing machinery. TCA is a volatile organic compound (VOC). "Volatile" means it vaporizes (evaporates) easily. "Organic" means it contains carbon. Tests show free product (solvents undissolved in water) floating on the water table about 25 feet below ground surface. free product is sometimes call non-aqueous phase liquid ( NAPL). The " Remedial Investigation" fact sheet has more information about Area 4 contamination.
What is the Source Area 4 proposed plan
For each source area, including Area 4, the Illinois EPA and U.S. Environmental Protection Agency ( U.S.EPA) propose one remedy for the contaminated soil and a second remedy for the leachate. The Illinois EPA and the U.S.EPA studied four alternatives for the soil remedy in Source Area 4 (Table 1). Of these soil alternatives, the agencies propose excavation and low temperature thermal desorption ( LTTD) (Alternative SCS-4D). The agencies studied five alternatives for Area 4 leachate (Table 2) and propose leachate containment / collection and treatment (Alternative SCL-4B).
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 4 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 remedy
The remedy has several purposes including:
- to stop ongoing contamination of the groundwater by Area 4 waste, thus protecting the water resource for future generations;
- to ensure that VOCs in soil gas do not move into basements of nearby homes and residences;
- to reduce the potential for people to come into direct contact with free product and contaminated soil beneath ground surface, and
- to comply with the 1995 Record of Decision for the project that required groundwater contamination sources be controlled.
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-4D and SCL-4B for Area 4
Soil excavation/ treatment and groundwater/ leachate containment and treatment are preferred for the following reasons. (1) SCS-4D substantially reduces risks by treating the contaminants in the soil including the free product, 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 4 remediation goals
Remediation goals are cleanup objectives. The goals for Area 4 are set for VOCs, because VOCs are the chemicals of concern in groundwater. The goals for the leachate are the federal drinking water standards at the GMZ boundary.
The soil goal is based on state guidelines called the Tiered Approach to Cleanup Objectives (TACO) for residential soil and protection of groundwater.
Semi-volatiles (such as chemicals found in oil and asphalt) were also detected in a few Area 4 surface soil samples. These chemicals are not found in groundwater so no remediation goals have been set for semi-volatiles at this time. The Illinois EPA will take more samples to see if they are contaminants of concern also, or if they are at concentrations that are commonly found in urban environments.
Commonly Asked Health Questions
Is my water safe to drink
If you are connected to the Rockford Public Water Supply, your water is safe to drink. 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.
Will vapors from Area 4 chemicals move into my basement
In 1992, the Illinois EPA and the Illinois Department of Public Health (IDPH) tested basement air in a home bordering Area 4. The home had levels of chemicals above health-based guidelines. There was an abandoned well pit in the basement which could have been the route taken by vapors from the soil to the house. IDPH recommended that the well pit be plugged, which the property owners did. In 1994, that home was resampled along with another basement adjacent to the site. IDPH stated that levels detected in 1994 were below levels of health concern. Since these chemicals are found in common household products such as paints and glues, it was not possible to determine the source of the low levels that were detected.
The U.S.EPA and Illinois EPA plan to repeat sampling of several homes near Area 4 during the design phase of the remedy-probably in 2001. These tests will make sure that levels have not increased and will provide data for U.S.EPA to compare to guidelines they are currently using.
| Table 1
Source Area 4
|SCS-4A No Action||No action.||60-70 years||None|
|SCS-4BLimited Action||Institutional controls. Institutional controls would be used to restrict use or access to the property until remediation goals are met.||60-70 years||$28,000|
|SCS-4C Soil Vapor Extraction|| Same as SCS-4B plus the following:
Soil vapor extraction ( SVE). Three vacuum extraction wells would be constructed in the contaminated area. Since Area 4 contaminants volatilize (vaporize) easily, suction on the system would withdraw the vapors from the air pockets beneath ground surface. If needed, steam injection and air sparging (injection of air beneath ground) could be added to increase the rate of volatilization.
Catalytic oxidation. 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 vapor and carbon dioxide plus hydrochloric acid. A scrubber would treat the acid to form water and salts. Neutralized water would be discharged to a nearby drainage ditch. See enclosed fact sheet on catalytic oxidation.
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.
Monitoring of water from scrubber. The scrubber water discharged into the ditch would be monitored to ensure it meets federal and state standards.
SCS-4DExcavation, On-site Treatment by Low Temperature Thermal Desorption
| Institutional controls. As described in SCS-4B except a restriction on excavation would be unnecessary since the contaminated soil would be removed in about a month.
Soil excavation. Approximately 2,800 cubic yards of contaminated soil plus the free productwould be excavated. Because of the levels of vapors in the soil, the excavation area would be enclosed and the vapors collected and treated on site. Since some of the contaminated soil is under the building, the Illinois EPA would decide during excavation if the building needs to be demolished.
Dewatering. Since the majority of the contaminated soil is below the water table, well points would be installed to lower the groundwater level to expose the contaminated soil for excavation. The collected water would be transported to an appropriate disposal facility
Mobile low temperature thermal treatment unit ( LTTD). Excavated soil would be treated on-site in a mobile low temperature thermal treatment unit. The LTTD unit would heat the soil to about 900(F at which point the VOCs would volatilize (evaporate) off the soil. The VOC vapors from the soil would be directed to a (1) baghouse where particulates such as dust would be removed, then to an (2) afterburner where vapors would be heated to 1400( to 1800(F. This high temperature breaks the VOC molecules into harmless chemicals such as oxygen and carbon dioxide plus hydrochloric acid. A scrubber would treat the acid to form water and salts. Neutralized water would be discharged to a nearby drainage ditch. After treatment is complete, the unit would be removed.
Monitoring of water from scrubber. The scrubber water that is discharged into the ditch would be monitored to ensure it meets federal and state standards.
Air monitoring. A proof of performance test would be conducted before standard operations. Air emissions would be monitored during standard operations to ensure all air quality standards are met.
Treated soil returned to excavation hole. The treated soil would be tested to verify that it meets the remediation goals. Soil meeting the goals would be returned to the excavation hole.
|Treatment of soil by the LTTDwould take approxi-mately one month. The leachate( groundwater) would meet goals in 5 to 15 years.)||$2,121,000|
* Length of time to reach remediation goals
| Table 2
Source Area 4
|SCL-4A No Action|| Institutional controls. Institutional controls would be used to restrict use or access to the property until remediation goals are met.
groundwater monitoring. groundwater would be monitored through a system of six monitoring wells until drinking water standards are met at the GMZboundary.
|60 to 70 years||$269,000|
SCL-4B LeachateContainment,And Treatment
| Institutional controls and groundwater monitoring. Same as described in SCL-4A.
Leachate containment and collection. Leachate would be collected through six extraction wells constructed with the purpose of preventing the leachatefrom moving past the GMZ boundary.
Air stripping. The leachate would be directed to an air stripping unit. Since the contaminants are volatile (they vaporize easily), they can be removed from the leachate by exposing the leachate to air and letting the contaminants evaporate-a process called stripping.
Treatment of vapors. Vapors from the air stripping system would either be directed to the catalytic oxidation unit for treatment if remedy SCS-4C were chosen for the soil, or vapors would be treated by a dedicated granular activated carbon (GAC) treatment unit that removes VOCs from vapors.
Air monitoring. Air released from the treatment unit would be monitored to ensure it meets all federal and state air quality standards .
Surface water monitoring. After the contaminants are removed from the leachate, the remaining water would be discharged to a nearby drainage ditch. The water would be monitored to ensure it meets all federal and state standards and requirements.
|SCL-4CInjection Wells, air sparging||This alternative could only be used with SCS-4C because it needs the soil vapor extraction system to collect the vapors and the catalytic oxidation unit of SCS-4C to treat the vapors.
Institutional controls and groundwater monitoring. The same as described in SCL-4A.
air sparging wells and injection unit. Air would be injected into the leachate/ groundwater increasing the amount of contaminants vaporizing from the leachate. In addition, steam could be injected into the ground, raising the temperature and thus causing increased volatilization of the contaminants.
|15 to 25 years||$2,522,000|
|SCL-4D Reactive Barrier Wall|| Institutional controls. Same as alternative described in SCL-4A.
Reactive barrier wall. A permeable wall of iron filings would be constructed downgradient of the GMZ boundary and beneath ground surface to a depth of approximately 60 feet where it would encounter a layer of low-permeable clay. As groundwater flows through the iron, chemicals found in Area 4 would react with the iron filings to form non-toxic compounds.
groundwater monitoring. Same as described in SCL-4A with the addition of two additional monitoring wells downgradient of the wall to make sure water leaving the wall meets drinking water standards.
|groundwater downgradient of the wall would meet goals as soon as the wall is installed. The wall would have to be used for approximately 30 years.||$5,911,000|
|SCL-4EEnhanced Air Injection and air sparging||Same as described in SCL-4C plus the following:
Enhanced air sparging wells. This alternative is similar to SCL-4C, but four additional sparging wells would be installed near the most contaminated area and operated with a vapor recovery system.
|10 to 20 years||$2,796,000|
|* Length of time to reach remediation goals
The Illinois EPA and U.S.EPA propose this alternative for the Source Area 4 leachate remedy.
How will the final remedy decision be 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 the consideration of these comments, the Illinois EPA and U.S.EPA will make a final decision on the Area 4 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 that will be mailed to interested parties.
Who will pay for the remedy
The Illinois EPA and U.S.EPA have been unable to locate responsible parties who are able to pay for the Area 4 remedy. Therefore, the chosen Area 4 remedy will be constructed, operated and maintained by funds from the U.S.EPASuperfund and the Illinois Hazardous Waste Fund.
When will the remedy be constructed
The Illinois EPA and the U.S.EPA plan to begin designing the selected remedy this summer or fall 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 4. 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.
- 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:
Community Relations Coord.
1021 N. Grand Ave. E.
Springfield, Illinois 62794-9276
Phone: (217) 524-2292
1021 N. Grand Ave. E.
Springfield, Illinois 62794-9276
Phone: (815) 223-1714
Repositories: Full reports for the project may be reviewed at the following locations.
Rockford Public Library
3128 S. 11 th Street
Rockford, IL 61109
(Call for hours)
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.