Story by Marie Donahue, Photos by Emily Cikanek
When one reads “radioactive material” and “groundwater” in the same sentence, it is easy to get a little nervous. Yet many people don’t realize that trace levels of radioactive materials, or “radionuclides,” are found naturally in some of the deep bedrock aquifers many of us in the Chicago area rely on for drinking water. These elements, most commonly the isotopes of Radium-226 and Radium-228, “occur naturally in rock formations deep below the surface of the earth and enter the deep aquifer water supply by bonding with the mineral deposits in the water,” explains David Heyden, who has become quite familiar with radium contamination issues over the past five years in his role as the Village of Lake Zurich’s public works director.
As “natural” as radium is, it certainly is not good for us. Exposure to elevated levels of radium in drinking water is linked to greater risk of bone cancer. Bones absorb the radiation, and it accumulates in the body. For that reason, the U.S. Environmental Protection Agency (EPA) requires that potable water contain less than 5 picocuries per liter of radium (a picocurie measures how many bursts of radiation a radium atom gives off per second.) For reference, the deep wells supplying water to the Village of Lake Zurich contained natural radium levels in the range of 5 to 15 picocuries per liter.
That’s where modern engineering and savvy water practitioners like Heyden come into the picture. Communities entrust these professionals with developing creative solutions to the most pressing water supply concerns, including removing excess radium from our drinking water.
Since Lake Zurich installed its first deep aquifer well in the 1960s, and the risk of radionuclides was first identified by the Clean Water Act in the late 1970s, radium contamination in the village’s drinking water supply has been a top concern of local residents and village officials. Heyden is charged with leading Lake Zurich’s effort to plan, manage and provide quality potable drinking water and wastewater services to the community, including addressing these radium concerns.
Early in Heyden’s tenure, he did not have direct experience with what at the time was a still relatively new technology: ion-exchange treatment, the physical process that removes hardness – and ultimately, radium – from drinking water. But he quickly enabled the village to reduce radium in its groundwater supply to below the legal limit. In less than two years, Heyden and the Public Works Department designed and constructed ion-exchange facilities on three active wells in the village; two ion-exchange plants had been installed before Heyden came aboard. The final plant began operating in December 2008, and since then Lake Zurich has achieved regulatory compliance, becoming one the region’s first communities “to utilize this technology for its entire system,” according to Heyden.
The ion-exchange process is not that different from a water softener in someone’s home—just on a much larger scale. As the name implies, a water softener removes “hardness” from water, defined as a concentration of multivalent cations, or ions, that enter the water supply by leaching from minerals naturally present in an aquifer. During the ion-exchange process, deep well water is pumped into large tanks where it passes through a charged medium that attracts and filters out the water’s hardness – in Lake Zurich’s case, the calcium and magnesium ions to which radioactive isotopes are attached. Eventually, the tank’s medium is at capacity, Heyden explains, “so that after a certain amount of time and a certain amount of water goes through the tank, we have to backwash it [with a salt-brine solution], just like the water softener in your home does.” The spent salt-brine solution is then pumped out to the wastewater treatment plant where it is separated and removed as sludge, which has been traditionally used as fertilizer in land applications.
Although the problem of groundwater contaminated by radium is not unique to Lake Zurich, the village found itself in an unenviable position of having few alternatives when it came time to tackle radium contamination in its deep wells. “At the time the Village of Lake Zurich was faced with meeting drinking water compliance, in the late 1990s, there was no alternate water supply available. Ion-exchange was determined as the most cost effective option,” Heyden explains. To date, Lake Zurich has spent nearly $10 million on constructing, operating and maintaining its ion-exchange facilities.
This solution, though costly, has worked for Lake Zurich for three years; however, the city might face some additional costs in the not-so-distant future. The U.S. EPA soon may tighten its limits on sludge or impose new regulations on treated wastewater discharged from existing treatment plants, like the one in Lake County where Lake Zurich sends its wastewater. “Either of these could result in significant impacts to our treatment process,” with very real consequences, explains Heyden. Looking at how many gallons of wastewater are produced through the village’s current ion-exchange process, its Public Works Department estimates that new regulation likely would cost an additional $1 million per year to haul the sludge to a special landfill. This added cost, Heyden explains, likely would translate to higher water and sewer rates for local residents and businesses.
In some ways, these proposed changes would put Lake Zurich back at square one, stuck operating an expensive system with limited options for the future of its water supply system. Looking at the glass half full, however, Lake Zurich’s water is clean of radium – and the village is learning important lessons. Indeed, Heyden believes the community is in a better position than ever to reassess its water supply alternatives. In the past year, the village was approved for an allocation of Lake Michigan water, which now can be considered a viable supply alternative to the deep aquifer. Of course, a switch to Lake Michigan water likely would come with its own set of costs and considerations. Lake Zurich would have to purchase this water from a neighboring community, translating to less certainty in treatment, infrastructure, and pumping costs. Furthermore, the U.S. EPA could strengthen its regulation of emerging contaminants (e.g., endocrine disruptors) found in surface water, making the treatment of Lake Michigan water relatively more expensive in the long run.
Regardless of whether the village of Lake Zurich remains on deep aquifer wells or opts to switch to Lake Michigan water in the future, the “20/20” vision David Heyden and his Public Works Department has put them in a much better position to make informed water supply planning decisions for the community in the years to come. Furthermore, the public outreach work that Lake Zurich has done concerning the radium contamination issue—this opportunity, for example, to take a behind-the-scenes look into the ion-exchange treatment process — gives the average consumer a better idea of the level of investment communities must make to provide us with safe, drinkable water each and every day.
In this video, Heyden explains more of the technical details and challenges of the ion-exchange process:
The WOWW factor
The maximum contaminant level for radium established by the U.S. EPA in the early 2000s. Communities must comply with this safe drinking water standard.
The estimated investment the Village of Lake Zurich has made in constructing, operating, and maintaining its ion-exchange facilities to remove radium from its deep groundwater wells.
The lifespan of one of Lake Zurich’s ion-exchange holding tanks — where the controlled radium removal process occurs. Due to the corrosive nature of the salt-brine solution used as a backwash, the tanks eventually must be replaced.
2 million gallons per day
The amount of water the Village of Lake Zurich pumps from the deep bedrock aquifer and treats through its radium removal process.
Water conservation tips
Observe local water conservation ordinances. For example, the Village of Lake Zurich Water enforces water conservation guidelines from June 1 through Sept. 15 for lawn watering and other outdoor uses, which are only permitted between the hours of 5 to 10 a.m. and 5 to 10 p.m. Be sure to check with your local water department and observe any water conservation ordinances to save water and avoid unnecessary fines!
Reuse water on a residential or commercial scale. An action as simple as using the water collected from your dehumidifier or air conditioning unit to water plants can help reduce the amount of water needed to be withdrawn and treated from our region’s deep wells.
Install native landscaping with deep-rooted prairie plants. Native vegetation helps infiltrate water back into the ground. Not only does this help recharge our region’s surface water and shallow aquifers, but plant roots are also great at filtering unwanted chemicals and contaminants out of stormwater runoff.
- Village of Lake Zurich: 2011 Water Quality Report
- Village of Lake Zurich Public Works Department
- Deep Bedrock Aquifer fact sheet
- “Radium in Drinking Water,” an article and FAQ from the Illinois Dept. of Public Health
- “Radium in Ground Water from Public-Water Supplies in Northern Illinois,” an article from the U.S. Geological Survey