Source Area 4
Results of Indoor Air Samples
Southeast Rockford Groundwater Contamination Superfund
Project
July 2004
Rockford, Illinois
Results of Indoor Air Samples
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.
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 house2 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.
Next steps
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.
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.
Soil Remedy
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 product1 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 Remedy
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 zone2 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.
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. 11th Street
Rockford, IL 61109
815-398-7514
(Call for hours)
|
Ken-Rock Community Center
3218 S. 11th Street
Rockford, IL 61109
815-398-8864
(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.
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