Environmental Progress - Summer 2003

Agencies Working to Correct Chronic Vapor Problems

Petroleum vapors build up in basements

Efforts are underway to resolve chronic basement vapor problems in homes in northeast Hartford, a small Madison County community along the Mississippi River. State and federal agencies are combining efforts to resolve the petroleum vapor problem that has plagued some residents for years.

Refining, storage and transport of petroleum products via pipeline have dominated industrial activity in northern Hartford for many decades. That long history of refining operations has been accompanied by a history of petroleum releases from pipelines and on-site units. Decades of releases have created a layer of gasoline and other petroleum products that lies on top of the groundwater under much of residential northeast Hartford. These phenomena have lead to a multitude of problems for northeast Hartford residents.

When levels of gasoline vapors in an enclosed space become high enough, explosions and fires are possible. Numerous fires attributed to gasoline vapors in basements of northeast Hartford homes were reported as early as 1970, with reports of fires continuing through 1990. Odor complaints, health concerns and vapor intrusions into area homes were also reported.

Complaints increased early in 2002

While reports of problems subsided for nearly a decade, due in large part to the operation of recovery wells and a vapor recovery system, the Illinois EPA and Illinois Department of Public Health began receiving reports from several northeast Hartford residents of petroleum odors in their homes in the spring of 2002. Residents also reported chronic headaches and occasional nausea.

The reports resulted in renewed efforts by state agencies, including additional investigation of the air in the basements of selected homes, during May and August of 2002. Based on the sampling results, the Illinois Department of Public Health determined that long-term exposure to these levels of volatile organic compounds found in the Hartford basements posed an acute public health hazard.

Currently, the Illinois EPA and the Illinois Attorney General are negotiating with several oil companies once active in the area to have them alleviate the vapor problem in residents' homes. The U.S. EPA has also been consulted and concurs with the state that the Hartford petroleum vapor problem and the source of the vapors must be remedied to protect human health and the environment. In addition, the Illinois EPA, Illinois Attorney General and the Madison County States' Attorney have filed suit against Premcor, and Apex Oil Company, the company that became Clark Oil, as two responsible parties for the pipeline releases.

Identification of other responsible parties is complicated by numerous factors including the large network of shared pipelines in the area, the proximity of several refineries' properties, changes in ownership and operation of pipelines and refineries, and historically incomplete records of releases at these facilities. The state has pressed oil companies that have operated in the area to fund and perform the investigative work necessary to resolve many of these outstanding issues.

Interim remedy proposed

As an interim remedy, the group of oil companies has proposed to install individual building remedial measures. The group, comprised of the Premcor Refining Group, Inc., Shell Oil Products US, Atlantic Richfield Company and Sinclair Oil Corporation, has agreed to perform an investigation of groundwater to determine the nature and extent of petroleum contamination under this area of Hartford.

Groundwater investigation work must precede development and implementation of a long-term remedy - the removal of the petroleum from the groundwater.

An "underground lake"

This "underground lake" of petroleum continues to be a serious problem directly affecting residents and the environment, as the groundwater table moves, rising and falling with changes in seasonal rainfall. The petroleum is carried upward with the rising groundwater table, moving into subsoils below structures. Once the groundwater table drops, the petroleum clings to the soils, and volatile chemicals in the petroleum infiltrate crawl spaces and basements through sumps, drains and cracks in foundations. This occurs most readily during periods of heavy rainfall when the vapors are trapped between saturated surface soils and the rising groundwater table.

Groundwater can also move horizontally over time, potentially carrying petroleum beyond historically affected areas. Natural groundwater flow direction, when not affected by industrial pumping in the area, is westerly toward the village of Hartford's public water supply wells and the Mississippi River. So far, the community's public water supply wells have not been impacted by the accumulation of petroleum.

Recovery wells tried earlier

In their earlier efforts, the Illinois EPA and Illinois Attorney General's Office had required Clark Oil to install petroleum recovery systems and in the 1970s, three recovery wells were installed in north Hartford to pump petroleum from the groundwater. These wells, however, are no longer operating. In the early 1990s, Clark was required to install a vapor recovery system to capture petroleum vapors in soils before they could reach area basements. This system, a network of underground pipes connecting a network of boreholes to blowers, creates a vacuum (low-pressure area) at the boreholes that pulls gasoline vapors from the surrounding ground. The vapors are piped to a thermal treatment unit located within the Premcor Refinery. Premcor reports that to date these systems have recovered more than 1.8 million gallons of vapor and 1.16 million gallons of liquid gasoline.