The City of Bloomington is engaged in a significant planning effort to find ways to expand its drinking water supply, with water director Brett Lueschen saying the city will likely need more water in the future.
“We've seen some growth within Bloomington, and we want to make sure that we have a good water supply to be able to plan for the future,” said Lueschen.
He said the city will likely issue a "request for qualifications," or RFQ, to find an outside firm to help.
"If we're looking at going somewhere else to get water for long term, there is going to be a lot of permitting involved with that and we just want to make sure that we have a good consultant that has had experience doing that before," said Lueschen.
The effort includes updating and reconsidering past work such as relatively recent bathymetric surveys of Lake Bloomington and Evergreen Lake to determine the level and rate of siltation in the lakes — how fast they fill in from drainage and erosion from surrounding land.
Dredging
One of the options is to dig sediment out of the two city reservoirs.
"We've looked at dredging several times in the past,” said Lueschen. "We do think that we would see some benefit if we were to do some dredging."
Lueschen acknowledged dredging is expensive. The City of Decatur recently finished a multi-year program of dredging in its own lake reservoir. The cost is not just from removing the sediment.
“You also have to have to have somewhere for that material to set and dry out and so forth,” said Lueschen.
Surveys done so far do not indicate the sediment in the Bloomington lakes has contaminants that would need special treatment, he said. The city would still have to test for nitrogen and phosphorus content of any dredged material, and the results could affect any disposal location.
The city does try to limit siltation, said Lueschen. It has shoreline stabilization projects and has constructed a couple of small wetlands at Lake Bloomington that allow eroded soil to drop out of drainage into the lake. Those also help by reducing nitrates that run off from fertilized farm fields.
“There are options out there for [more] wetlands, and doing other floating wetlands,” said Lueschen. “Basically, you take a plant and put those into where the watershed comes into the reservoir. Those eat up the nitrates and stuff like that that's coming into the water.”
Groundwater
A much older study that contemplated a regional well field that taps into the Mahomet Aquifer west of the city also could get a second look, and involve multiple municipalities and a new treatment plant. The idea foundered a couple decades ago over cost and water sharing agreements with other governmental bodies.
The city previously expanded its water supply by raising the dam and spillway at the two reservoirs. Lueschen said doing that again, even with a small increment, would not be feasible.
“There are houses there along [Lake] Bloomington, and some of those houses are pretty close to the shoreline. Just raising it just 5 inches would actually impede on some of those residential properties that are up there,” he said.
Years ago, the city drilled two deep test wells into a different underground water source than the Mahomet Aquifer. Lueschen said the wells in St. Peter Aquifer did not offer a significant enough upside.
“We would be looking at about a million gallons per well per day,” she said.. “There are some concerns with the sodium that's in the water, but also some radium. We felt that was not a very good option with not getting the yield and the restraints we have with that water quality.”
He said lime softening and other treatments of that water would make it usable, but given the quantity, it would not be cost effective as a long-term option for Bloomington.
Other surface water
Lueschen said there may be options to expand the city system from other surface water sources than the lakes the city now uses.
“I don't want to speak too specifically to some of those. We are looking at where can we get water for a long term, for the City of Bloomington,” said Lueschen. “I don't want to get the cart before the horse.”
He said the city may wish to pursue a both-and strategy to get new water from more than one place.
“It very well could be. As we work into some of these studies, that will be determined,” said Lueschen.
Water infrastructure spending
There is about $82 million in water department infrastructure in this year’s city budget. About $10 million of that will go to lead line removal, according to a long-term plan to meet a federal mandate.
That phase one work will happen in census tract 59, roughly south of Downtown, from Bunn Street to the Miller Park area.
“We only received one bid on the project. We'll be looking at taking that to council in April for approval to move forward with that contract. That's going to take about 600-603 lead service lines of replacement ... and we're looking at probably 18 months of construction,” said Lueschen.
The city is starting a year ahead of the opening of the 10-year window the federal mandate imposes. Lueschen said he feels the city is in good shape to meet the deadline, adding he hopes there will be other bidders in future years.
“Hopefully, it doesn't become a bottleneck. Hopefully contractors will see that, hey, that this contractor for this phase one did a very good job. It wasn't as bad of a project as maybe they were anticipating. Maybe that's why we only received one bid,” he said.
The rest of the spending, Lueschen said, will be on other aging infrastructure replacement projects.
“System-wide distribution improvements. That will be coming out to bid in April," he said. "That's giving us some more storage for water. It also is going to provide us with a couple pump stations that will help bring the water into the city. It's taking care of some of our aging transmission mains that actually run through the Town of Normal to take water down to our Division Street office.”
The city also will do design work on six miles of water main replacement. Construction could happen next year.
PAC silo
The city has taken delivery of a new silo/storage module for powdered activated carbon [PAC]. That’s what the city uses to address taste and odor issues that have cropped up occasionally. Lueschen said the city is working on the foundations for a support building for the equipment used to inject carbon into the water as it flows to residents.
“Hopefully, sometime here in the beginning of June, we'll see the system up and running,” said Lueschen.
The city already is treating its water with PAC, but has had to rig up a smaller scale system for storage.
“We took an old storage tank, and the crews basically mixed this out in the parking lot. We do have the Illinois EPA permit as a temporary system, and the crews mix the solution out in the parking lot. You can only imagine, when it's cold, when it's snowing and stuff like that. It makes it challenging, Powdered activated carbon is a very, very light, fluffy material and stuff. Just a little bit of wind could blow this material,” said Lueschen.
The temporary system contains 3,000 gallons of PAC solution. Lueschen said that lasts about a week. He said the new silo will take a full semi-load of PAC. And there is significant cost savings for buying PAC in bulk.
