The City of Sun Prairie and RMT Engineering have received the Wonders of Wisconsin Engineering Award from the American Council of Engineering Companies.
The honor -- for the best environmental project over the past 50 years -- was presented Friday. It recognizes the contaminant clean-up that occurred at the site of City Hall prior to its construction.
During the excavation, workers discovered five tanks that had been used by a dry cleaning operation. The tanks had holes in the bottom from which their chemical contents were drained into the surrounding ground.
"The DNR indicated that they would only accept a pump-and-treat system to clean up the problem," said City Administrator Pat Cannon. "The estimated cost was between $8 million and $10 million. The process would have taken about 20 years to complete."
After studying the situation, RMT engineers said it was unlikely a pump-and-treat system would work with the chemicals involved. They developed an alternative solution that would stimulate the microorganisms, breaking them down to a non-hazardous state.
"After working with DNR, we were allowed to install this process on a trial basis," said Cannon. "After a year of monitoring, it was determined that our results were better than expected. In fact, the DNR issued a closure letter on this project last week."
The cost to complete the system was about $800,000 -- 10 percent of the original estimate.
Several other sites have since used this process to clean up contaminated soil.
