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 Peoples Gas Crawford Site is located in Chicago, Illinois. Crawford was built in 1921 as a gas production and storage facility and was one of the largest facilities of its kind. It was operated as such until 1963. 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're helping to clean up Chicago
In 2011, Peoples Gas joined forces with the Illinois and United States Environmental Protection Agencies to remove significant sources of MGP contamination in the soil. The process included demolition and removal of old underground foundations, and landfill disposal of impacted soil and debris. To date we have removed over 850,000 cubic yards of impacted material making this one of the largest MGP cleanups in the country.
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 are collected during the project. The samples are analyzed and reviewed by the United States Environmental Protection Agency (EPA). We do 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 cleanup is being performed in phases and the final phases are scheduled to be completed in 2016. We worked with many local vendors and diverse suppliers during the project.