Restoring former gas plant sites

Times change, technology advances and knowledge grows. We now know that the way manufactured gas was made in the past caused unintended consequences for the environment. We restore these areas to improve the natural environment.

The history of manufactured gas plants

From the early 1800s until the 1960s, local plants manufactured gas for heating and lighting. These plants were the pride of many cities because gas was a better source of energy. Gas lights replaced oil lamps, and gas eliminated the need to cook and heat with wood or coal. The plants prospered until more affordable, cleaner natural gas began to arrive by pipeline. There were about 2,000 to 2,500 gas plant sites in the U.S.

The former North Shore Gas - North Plant is located in Waukegan, Illinois. North Plant was built in 1912 as a gas production and storage facility. It was operated as such until 1953. In the late 1960’s, the aboveground manufactured gas plant (MGP) structures were removed.

Environmental issues with manufactured gas plants

The process of manufacturing gas resulted in byproducts. This included tars, oils, and wood chips. Many plants sold the byproducts, especially the coal tar, which could be distilled and used in dozens of products, including fuels, fertilizer, creosote, plastics, and pharmaceuticals.

Byproducts that could not be sold were sometimes left on site. At most plants, storage tanks were made of wood or brick, with piping and other equipment that may have leaked. When the plants were demolished, some waste may have been left on site. At the time, there were no regulations for disposing of such materials, and these practices were common. However, the result is that some byproducts are still present in the soil today. At the depths where they typically occur, they don't present a hazard to people on or near the site. But they do need to be cleaned up to protect groundwater beneath the site.

The chemicals under the sites fall into three main categories:

  • Volatile organic compounds, like those found in gasoline.
  • Polycyclic aromatic hydrocarbons, which are present in byproducts of incomplete combustion (such as car exhaust), asphalt roads, roofing tars, grilled food, and other common materials.
  • Inorganic compounds such as metals, which came from the coal and gas purifying process.

We helped to clean up Waukegan

In 2013, North Shore Gas joined forces with the Illinois and United States Environmental Protection Agencies to remove or solidify/stabilize significant sources of MGP contamination in the soil. The process included demolition and removal of old underground foundations, some landfill disposal of soil and debris, and In-Situ Solidification/Stabilization (ISS) of impacted soil.

ISS is a process that mixes contaminated soil with cement based grout. This physically and chemically solidifies and stabilizes the soil into a material like low-strength concrete. The process stops chemicals from moving into the environment or groundwater. This cleanup method can be done much faster and more efficiently than conventional excavation/disposal. Especially on a site like North Plant that has extremely sandy soil and a shallow groundwater table. This project treated up to 300,000 cubic yards of soil.

As with all MGP clean-ups, odors occurred during the project. The odors were similar to the smell of asphalt, gasoline or tar.

We took action to help control the odor by:

  • Applying a foam that helped to limit odor
  • Covering exposed material with plastic sheeting
  • Using a misting system around the edge of the project

Air samples were collected during the project. The samples were analyzed and reviewed by the United States Environmental Protection Agency (EPA). We did this to confirm that nothing harmful was being released into the air. We also worked with local officials, residents and the EPA on this matter.

The project was completed in November 2014. The North Plant project cost approximately $27 million dollars. We worked with many local vendors during the project.