"Radio Jamming," Feature Article, February 2003

radio jamming

An Illinois town blocks radium from its water.

by Harry Hutchinson, Executive Editor

Radioactivity in water supplies is common enough in the United States that the Environmental Protection Agency has a rule about it: no more than 5 picocuries in a liter of drinking water. That posed a problem for the city of Ottawa, Ill., which in the past has pulled samples of its water ranging from a radioactivity rate of 3.8 picocuries, comfortably within acceptable limits, to a high of more than 12 pCi per liter.

Ottawa brought in McClure Engineering, a private firm based in East Moline, Ill., to work out a remedy. Jack Kusek, the project manager at McClure, said the company recommended four banks of reverse osmosis membranes to filter radium from the city's water.

According to Gary Pike, Ottawa's city engineer, the systems were brought on line in stages in June, July, and August last year. Three units are at Ottawa's Central Plant, which has a potential output of 4.5 million gallons a day, or some 17 million liters. The fourth unit is at a site called Well 10, which can pump 1.6 million gallons a day, or about 6 million liters. There is room to add one more system at the Central Plant.

Each unit can process 825 gallons a minute. Each stream of treated water will mix with a smaller stream of untreated water flowing at a rate of 125 gallons a minute.

Pike said the capacity of the systems will let the city meet peak demand with one unit out of service.

The filter systems came from Osmonics Inc. of Minnetonka, Minn., a company due to be acquired by General Electric this month. Craig Beckman, the sales manager, said each unit has a series of semipermeable membranes that let water through, but repel a variety of contaminants, including heavy metals, cryptosporidium, and giardia. The membrane is not proof against volatile organics, he said. Benzene and toluene, for example, can pass the barrier.

Beckman said that the strongest markets for reverse-
osmosis filters are in industries that need to treat water. Over the past couple of years, though, the company has packaged a version specifically for the municipal market.

Reverse osmosis membranes in Osmonics water filtration systems like these are cleaning radium from the drinking water supply at Ottawa, Ill.

The system is designed to pump water to the membranes at high pressure, between 100 and 200 psi, or about 700 to 1,400 kilopascals, Beckman said. Most of the pressure is lost after the water travels through the barrier. Chlorination and fluoridation occur afterwards.

Doug Carroll, Ottawa's city planner, said that initial tests showed an 85 to 90 percent reduction of radium.

Pike said that Ottawa's water is treated before filtering with sulfuric acid and an anti-scalant that keeps dissolved salts from plugging up the membrane. Tests indicate that removal of salts reduced water hardness by 60 percent.

According to Pike, the concentration of removed radium is not considered high, so it is flushed to storm sewers and eventually to the Fox River, where it will disperse.

Ottawa has had other problems with radioactivity. Fourteen areas in and near the city are regarded as one Superfund site. For 60 years, two companies, Radium Dial Co. and later Luminous Processes Inc., painted glowing watch dials and clock faces with radium-based paint. Over the years, contaminated waste from the factories had been used as landfill.

Denise Boone, project manager for the cleanup in EPA's Region Five, said that nine affected properties have received a clean bill so far. The agency has installed remediation equipment and removed between 30,000 and 40,000 cubic yards of radioactive soil and debris at Ottawa.

The city, whose population is about 18,000, is in the Illinois River Basin, on Route 80, about 60 miles or so southwest of Chicago. According to a 2001 report by the U.S. Geological Survey, radioactivity troubling the aquifers in the Illinois River Basin is attributable to glacial drift deposits of uranium, dating from a time long before radium watch dials—as far back instead as the Illinoian and Wisconsinan stages of the Pleistocene Ice Age, which started at least two million years ago.