Imagine a world where water supplies are plentiful, cheaper to heat, easy on the water main system and filtered to near perfect purity levels by Mother Nature.
For the last 10 years, the Louisville Water Co. has been working to make that dream a reality with its massive Riverbank Filtration project, set to be completed by late 2010. The project will be the only one in the world to combine riverbank filtration technology with a 7,800-foot-long tunnel that is 150 feet below ground, producing a water product that comes out 99.99 percent pure and a perfect 50-60 degrees.

“We began this project 10 years ago, in anticipation of new regulations being imposed by the Environmental Protection Agency for 2012. Our current system filters water down to 99.9 percent (purity), but by adding the extra protections we’ll be able to filter out pathogens like cryptosporidium and giardia, and filter out pharmaceutical waste better, too,” said Greg Heitzman, president and CEO of the Louisville Water Co. 

When complete, most of Louisville’s East End will be supplied by the riverbank filtration project. Company officials are currently evaluating whether to continue with riverbank filtration for the water company’s second treatment plant in Crescent Hill, or go with other technologies such as ozone, UV light, membrane filtration or carbon absorption. An internal committee is expected to make that decision by the first quarter of next year, Heitzman said.

Nature’s perfect filter
A concept that’s been around since the 1940s, riverbank filtration works by tapping into a river or lake’s “aquifer” – the layer of sediment, sand and porous rock that underlies the river bottom and the swampy areas around the river. 
This project includes a recently completed 12-foot diameter tunnel underneath the aquifer, with a series of wells popping up into the aquifer. The water flows through the sediment in the aquifer and into the tunnel. The tunnel then uses the natural downward slope of the river to transport it back to the pumping station.
“This project is really very different than other places where riverbank filtration has been used, like the Rhine River in Germany,” said Kay Ball, manager of Riverbank Filtration and Advanced Treatment Technology for Louisville Water Co. “There, they have no tunnels. They have large, above-ground pumping stations all along the river, connected by pipe. With our system, we’ll have just one pumping station, and an underground tunnel embedded directly in the bedrock. It gives us a very secure source of water,” she said.

A unique competitive edge
While other cities like Atlanta and Nashville struggle to find enough water to fuel their growth, the riverbank filtration project will give Louisville a consistent supply of high-quality water. Enough, Heitzman noted, to even pipeline it out to other nearby communities. In fact, the water company began construction in 2008 on a 36-inch pipeline along Interstate 265 to supply eastern Jefferson County, and position the company to provide additional water to Shelby County and beyond into central Kentucky.

Louisville Water made a serious bid to become a major provider to the Lexington area, which was experiencing tight supplies due to drought in 2007. The central Bluegrass region opted instead on a plan now under construction that taps the Kentucky River in a new location.

Proposals are under consideration for Louisville Water Co. to supply wholesale water to Elizabethtown, and to operate the growing Fort Knox water system.

“If you don’t have a good water supply, the community can’t grow,” Heitzman said. “This riverbank filtration project will put us above all our regional city competitors. It’s an important advantage to have, especially for manufacturers who will need a good water supply to run their facilities,” he added.

The riverbank project also has a host of other advantages, including:

• Cheaper to heat – With Louisville’s seasonal swings in temperature, water coming from the Ohio River can be anywhere from 30 degrees to 100-plus degrees. The aquifer filters out impurities, and it also naturally regulates its temperature to a consistent 50-60 degrees, no matter the time of year. This cuts consumer’s electricity bills, as they only have to heat the water a few degrees for most household purposes.

• Fewer water main breaks – By cutting back the extremes in temperatures of the river water, the riverbank project also will help prevent freezing, swelling and breakages in the water mains. Experts predict the riverbank project will cut down water main breaks from 800 to 400 yearly. The system also eliminates clogs from marine life like mussels that plague the current system.

• Minimal environmental impact – Because the majority of the system is buried far underground, the riverbank project eliminates the need for aboveground piping or pumping stations that mar the river landscape. 

• Better water supply security – With tunnels buried deep within the limestone bedrock, the system will be impervious to floods, tornadoes and hurricanes. The tunnels are even earthquake resistant, as bedrock is rarely affected in an earthquake.

• Cheaper long-term operating costs – While Louisville Water Co. will make a $50 million investment to create the riverbank filtration system and its other infrastructure improvements, it’s yearly operating costs are far less than other purification methods. Ozone filtration, for instance, costs $1-$2 million yearly to operate, while the riverbank system will run for $500,000 yearly.

Starting in January of 2009, customers served by the water company’s B.E. Payne plant received a 5 to 5.5 percent increase in their monthly water bill, to help cover the costs of the project.  By 2012, that amount will be reduced to 3-4 percent above previous rates, Heitzman said.

The aquifer gives Louisville Water Co. access to as much as an additional 280 million gallons a day, although the company only has the production capacity to pump 240 million gallons daily.  And this is still far higher than demand, which in Louisville, can range from 110 million gallons daily in the winter months to peaks of 200 million during the summer. Water pulled from the aquifer will mainly be used at the BE Payne treatment plant, which services east Louisville.
The company, however, has a “redundant system,” which allows it to pump water from one treatment facility to another, allowing the entire city to benefit from the filtration project.

Though more work is to be done to upgrade filtering systems at the company’s Crescent Hill treatment plant, Louisville Water Co. officials are optimistic about the changes riverbank filtration, and further improvements, will bring. 

“We’ve known riverbank filtration could work in Louisville since the 1940s,” Ball said, “but we didn’t have the technology to bring in enough water volume. Now we do, and it’s becoming reality. It’s neat to think that Louisville, the city that has pioneered so much in the safe water field, is doing it again.”