ALTON – By the second quarter of 2020, the location of the former post office on Belle Street in Alton will be available for redevelopment – assuming all goes well with Ameren's plans for remediation at the lot.
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Monday morning, Ameren Illinois invited members of the media to tour the remediation efforts on the site. Because of the amount of local small businesses and traffic near the site, Ameren Illinois opted against its usual remediation treatment, which involves massive excavation with several trucks hauling tainted dirt from the site just for it to be replaced with clean dirt. Instead, it is using a multi-phase thermal remediation system. The technology is not new to the industry, but Ameren Illinois is utilizing it for the first time in Alton.
“Usually, we would place a large circus-tent-looking structure over the site and excavate it,” Environmental Specialist and Site Manager Brian Holderness said. “This way is about a third as expensive, and while it does use a lot of electricity, does not have the environmental impact of all those trucks coming in and out and carrying away dirt. People don't really seem to like that many trucks coming and going. Also, we would have to had to buy a lot of sites around this one to do that, and our studies showed that would have a negative impact on the area.”
The site requires the remediation due to the existence of a manufactured gas plant on that site. That plant was constructed in 1855 by the Alton Gas and Electric Company, and continued working through 1941 to provide natural gas to the people of Alton, which was used for a variety of things, including cooking and lighting the city. It was purchased by Union Electric Company in 1937.
Due to its previous life as a manufactured gas plant – especially during periods of history in which the environment was a distant afterthought – the site contains some coal tar and other pollutants seeping from previously-buried containers. Holderness said the contaminants have leaked into the soil and are doing what they are to do – seeping toward the lowest point.
Because of this, wells have been dug as deep as 50 feet, or five feet into solid bedrock, to extract these contaminants. Holderness said some of the pollutants have reached ground water, but a city ordinance makes extraction of ground water illegal in Alton, meaning it is relatively contained within its system.
The extraction process, which uses heat and a vacuum pump to remove both liquid water and steam from the ground, will send the contaminants through a multi-phase extraction system. Water and steam are sent via on-site piping to water containers and a thermal accelerator. When pumped from the ground, the water is around 212 degrees Fahrenheit. That temperature increases to around 1,400 degrees when it is pumped into the thermal accelerators.
Once in the tanks, water and oil-based contaminants are separated. The water is then filtered through a bag filter, through clay and then finally through activated charcoal before being sent to the water treatment plant for final treatment. It will end that process by being purified and emptied into the Mississippi River.
The contaminants will be placed into holding containers before being sent for disposal. What will be left in the soil after this process, which is expected to take as long as 225 days, will be non-hazardous rocks reminiscent of regular hunks of coal, which Holderness said may be taken to regular landfills for disposal.
Following remediation, all equipment and pavement will be removed from the site, including the former base and foundation of the old post office. The newly remediated dirt lot will be available for redevelopment after that.
During the process, people around the site can expect some construction-based noises as well as some ambient hums from the multi-phase extraction working. There will also be some closures of the sidewalk in front of the site and parking lane due to the need to move equipment.
If the public has any questions regarding this remediation, they are invited to contact Stacey Stockton-Shangraw of Ameren Illinois at (309) 677-5073 or via email at Shangraw@ameren.com or Jay Timm of the Illinois Environmental Protection Agency (EPA), which is working with Ameren Illinois for this proactive remediation effort. Timm can be reached at (217) 557-4972 or via email at jay.timm@illinois.gov.
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