Fact Sheet 13a
Source Area 4 Results of Indoor Air Samples
Southeast Rockford Groundwater Contamination Superfund Project
What is Source Area 4?
Illinois EPA investigations beginning in 1991 identified Area 4 as one of four major sources of private well contamination in southeast Rockford. The investigations showed that sources of contamination in Area 4 appear to be spillage/disposal and an underground storage tank. Contaminants include waste oils and the industrial solvents 1,1,1-trichloroethane and trichloroethylene. Information on the other three source areas is available from sources listed on the last page.
Is my water safe to drink?
Area residents who are using Rockford Public Water Supply do not have to worry about the safety of their drinking water. The Rockford Water Supply is regularly tested for possible contaminants. Water that violates U.S. Environmental Protection Agency (U.S. EPA) drinking water standards is not distributed to the public.
Results of Indoor Air Samples
In August 2003, the Illinois Environmental Protection Agency collected indoor air samples from four homes near Source Area 4 of the Southeast Rockford Groundwater Contamination Superfund Project. (See the map below.) The Illinois EPA collected and analyzed these samples to make sure that underground vapors from the source area are not moving into the basements of nearby homes.
How does Illinois Department of Public Health evaluate these sample results? In a letter to owners and renters of all sampled homes, with the exception of a home with an unsealed well pit, the Illinois Department of Public Health (IDPH)) stated that the levels of VOCs (volatile organic compounds) 1 detected in the Area 4 indoor air samples would not be expected to cause short-term or long-term health effects and would pose no apparent increased risk of cancer.
In the letter to the owner and resident of the home with the well pit, IDPH stated, “The levels of VOCs detected in your basement would not be expected to cause short-term health effects. Exposure to the level of TCE (one chemical) detected in your basement over a period of many years may present a low increased cancer risk. Based on the results of your sample, we recommend that the well pit in this basement be sealed in such a way to reduce VOCs entering the home.” Since then, the owner of the house has sealed the well pit.
In general, what were the sample results from the four Area 4 homes and how did results compare to the background sample? It is difficult to evaluate indoor air samples, since most of these chemicals are found in common household products such as solvents, paints, cosmetics and glues. They are also commonly found in urban outdoor air. With those uncertainties in mind, a summary of Illinois EPA findings follows:
- All houses, including the background house 2 used for comparison, slightly exceeded the most conservative U.S. EPA indoor air screening values for three to five chemicals. Screening values are not action values but values that indicate the Illinois EPA should take a closer look. They are conservative in that they assume that residents live in the sampled area (the basement) 350 days a year, 24 hours per day for thirty years. It is not surprising that chemicals were detected in the background comparison house because of the presence of these chemicals in household products.
- The house that had the overall highest concentrations had an improperly sealed well pit in the basement, which could have provided a pathway for underground vapors to seep from the outside into the basement. Since the sampling date, the Illinois EPA has been notified that the well has been sealed, and the agency is waiting for certification that the seal meets state regulations.
- Chemicals associated with gasoline slightly exceeded U.S. EPA guidelines in all the houses. Since these chemicals are not found in the underground vapors, their source must be gasoline or other products stored in the houses or fumes in the outside air from automobile exhaust.
- All the chemicals that exceeded U.S. EPA indoor air guidelines were found, for the most part, in the outdoor air sample collected near the same house. Again, this is not surprising since these chemicals are commonly found in urban air.
Predesign work for the Area 4 remedy has begun. The Illinois EPA anticipates that the actual design will be completed in 2004. Construction of the remedy is planned for 2005 if funding is available. When the design is complete, the Illinois EPA will apply to the U.S. EPA for funds. This site will have to compete with other sites across the nation for the limited federal funds available for cleanup of Superfund sites.
What is the predesign work? Predesign work includes collecting additional information that is needed to complete the remedy design. Much of the fieldwork for predesign occurred in March. The fieldwork included:
- locating underground utilities,
- testing leachate to determine if it will need to be pretreated to remove iron and manganese before it is directed to an air stripper and
- soil sampling beneath the existing on-site building (the former Swebco building). These samples will be collected to evaluate the amount of soil beneath the building that may need to be remedied.
The Illinois EPA has placed a report of the predesign investigation results in the two local repositories for public review. Locations of the repositories are listed on the last page.
What is the design work? The design includes developing the actual plans and specifications for the remedy and will include:
- description of the methods that will be used to verify that air emission standards, cleanup objectives and other federal and state requirements are met,
- health and safety plans and
- construction cost estimates and schedules.
Area 4 Remedy
What is the Area 4 remedy? In June 2002, after considering public comment, the Illinois EPA and the U.S. EPA chose low temperature thermal desorption (LTTD) and leachate containment and collection as the Area 4 remedy. See page 3 for more details on the remedy. The remedy will remove the major source of underground vapors and will draw back vapors in the immediate vicinity of the source.
What is the source of funding for the Area 4 remedy? The remedy will be 90 percent funded by General Appropriations from the U.S. Congress and 10 percent from the Illinois Hazardous Waste Fund.
1Volatile organic compounds are the chemicals of concern in Area 4. The chemicals are called “volatile” because they vaporize (evaporate) readily and organic because they contain carbon. The VOCs found in Area 4 are primarily industrial solvents.
2Background samples are samples collected in areas thought to be unaffected by contamination. They are collected for comparison to samples taken closer to the contamination.
Source Area 4 Remedy
The remedy for Source Area 4 is divided into two parts. One part is for soil and the other is for leachate.
Institutional controls. Institutional controls are administrative or legal constraints that place limits on the use of land or a resource. For example, there will be a control prohibiting the use of groundwater for drinking.
Soil excavation. Approximately 2,800 cubic yards of contaminated soil plus the free product 1 will be excavated. Because of the levels of vapors in the soil, the excavation area will be enclosed and the vapors collected and treated on site.
Dewatering. Since the majority of the contaminated soil is below the water table, well points will be installed to lower the groundwater level to expose the contaminated soil for excavation. The collected water will be transported to an appropriate disposal facility.
Mobile low temperature thermal desorption (LTTD) unit. Excavated soil will be treated on-site in a mobile low temperature thermal desorption unit. The LTTD unit will heat the soil to about 900°F at which point the VOCs will volatilize (evaporate) off the soil. The VOC vapors from the soil will be directed to a (1) baghouse where particulates such as dust will be removed, then to an (2) afterburner where vapors will 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 will treat the acid to form water and salts. Neutralized water will be discharged to a nearby drainage ditch. After treatment is complete, the unit will be removed.
Monitoring of water from the scrubber. The scrubber water discharged into the ditch will be monitored to ensure it meets federal and state standards.
Air monitoring. A proof of performance test will be conducted before standard operations of the LTTD unit. Air emissions will be monitored during standard operations to ensure all air quality standards are met.
Treated soil returned to excavation hole. The treated soil will be tested to verify that it meets the remediation goals. Soil meeting the goals will be returned to the excavation hole.
Leachate is contamination that has moved or could potentially move into the groundwater. For purposes of this fact sheet, leachate includes the groundwater at Area 4 that must be contained or controlled to protect human health and the environment.
Institutional controls and groundwater monitoring.
Leachate containment and collection. Leachate will be collected through six extraction wells constructed with the purpose of preventing the leachate from moving past the groundwater management zone 2 boundary (GMZ) established around Area 4.
Air stripping. The leachate will 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 will be treated by a granular activated carbon treatment unit that removes VOCs from vapors.
Air monitoring. Air released from the treatment unit will 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 will be discharged to a nearby drainage ditch. The water will be monitored to ensure it meets all federal and state standards and requirements.
1 Free product occurs when a contaminant is present in high enough concentrations in groundwater that 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
2 A GMZ is the 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 the groundwater at the GMZ boundary meets Class I Groundwater Standards, which are based on federal drinking water standards. The map on page 4 shows the approximate boundary of the GMZ for Area 4.
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.