Environmental Progress - Winter-Spring 2004

Hartford Area Vapor Investigation

Oil companies sign agreement to address petroleum vapors and contamination

On March 17, 2004, the United States Environmental Protection Agency signed a legally enforceable agreement with the Hartford Working Group (HWG), which is comprised of Atlantic Richfield Co.,

A petroleum vapor collection system operating in the Hartford community.

Equilon Enterprises LLC doing business as Shell Oil Products US and the Refining Group. This agreement, an Administrative Order of Consent, obligates the HWG to complete a thorough investigation of petroleum contamination in residential Hartford by the end of this year. This represents an important step toward resolution of the problems caused by a long history of petroleum releases in Hartford.

The numerous releases have, over the years, created a layer of gasoline and other petroleum products that lies under much of residential northeast Hartford. The petroleum percolated down through the soil and now floats on the top of the water table. The releases have been attributed to Hartford Working Group members and their predecessors, along with some other oil companies that have not agreed to enter into the AOC.

Among other things, the AOC requires the oil companies to find ways to protect the residents from vapors, investigate the ways vapors are getting into homes, study the vapor removal system that was installed in the early 1990s, protect the public water supply, pump out petroleum and design a permanent remedy to the contamination.

Protecting residents from vapors

As part of the agreement signed by the companies, the HWG is required to develop a plan for responding to complaints of vapors in homes. The companies have agreed to provide temporary housing and pay for meals, if residents need to be temporarily evacuated from their home.

In addition to the requirement to be responsible for evacuation costs, an important measure included in the AOC requires the HWG to find ways to protect the residents from vapors in their homes while the other investigations continue. In some cases, interim remedies may be employed until a long-term solution can be implemented.

Studies are being conducted at two houses in north Hartford to determine the most effective way to protect residents. At one home, a hole was drilled through the basement floor that extended about one foot into the soil below. Piping extends up from the basement and out through the side of the house, along the exterior wall to the roof. A fan is used to draw the vapors from beneath the basement floor up through the pipe.

Investigating the ways vapors are getting into homes

In addition, household "needs assessments" are being performed in order to evaluate basements in the area and develop interim remedies where necessary. These remedies may range from either of the two whole-house systems described above to installing exhaust fans, caulking basement wall and floor cracks, or installing water traps in floor drains. The U.S.EPA, Illinois EPA, Illinois Department of Public Health and the Illinois Attorney General's Office all endorse the needs assessments process and its goals.

Another related investigation will include identifying all utilities, sanitary and storm sewers, and pipelines in Hartford. It appears that these systems have become pathways allowing the petroleum vapors to reach homes. This investigation will help to determine what other efforts may be needed to stop vapors from getting into homes. A report on the results of this investigation is expected by June 2004.

Studying the existing vapor removal system

The companies are also evaluating the effectiveness of a system of vapor extraction wells that was installed in the early 1990s. Those wells were designed to pull vapors from the soil through pipes, then the vapors are treated in a Thermal Treatment Unit on the former Premcor refinery property. Recent testing of parts of the existing system revealed that clogging of several wells resulted in reduced vapor extraction from the surrounding soils. This might explain why odor complaints increased in the area despite the system's continued operation. The HWG is studying the effectiveness of a newer type of extraction well in the collection of vapors. One of these newer extraction wells has been installed and is being tested

Protecting the public water supply

Five monitoring wells have been installed between the area affected by the contamination and where the village water wells are located. These "sentinel" wells are being monitored to ensure that the underground contamination does not reach the village water supply. The results of the samples taken from the sentinel wells so far have shown no contamination, indicating that Hartford's public water supply is safe from the petroleum contamination.

Designing a permanent cleanup

In the AOC, the companies agreed to design a long-term solution to clean up the contamination in the ground. The specifics of the cleanup will depend on the results of the investigations that are underway. One of these investigations collected data from numerous locations across northeast Hartford to find out if there are petroleum products in the soils and on the groundwater at each location. An instrument called a Rapid Optical Screening Tool was used. This device uses a laser and sophisticated sensor to detect hydrocarbons and measure their relative concentrations. When the laser light passes through a petroleum product, the product emits fluorescent light at a wavelength characteristic to the size of the product's molecule, registering its presence with the sensor. This investigation along with others the HWG will perform this year will help determine where and how widespread the contamination is and the best way to design a permanent cleanup.