Thirty or so years ago, a big day of production  was a time to celebrate for a water plant team.

“When I came here in 1986, we were proud of every day we set another record,” says Don Jensen, superintendent of water production in Highland Park, Illinois. “At that time, our plant was rated at 21 mgd, but for short periods we could exceed that and still maintain good-quality water. It was a feather in our cap to put out 24 or 26 mgd. We actually had a 28-million-gallon day.”

How times have changed! Now it’s lower production that gets the accolades. In the 1980s, average output at the George B. Prindle Water Treatment Plant was 10 to 11 mgd. Today it’s 7 to 8 mgd, and that’s despite a population that has remained relatively stable. Typical peak days during summer range from 18 to 22 million gallons.

Jensen believes the reductions are due to the gradual deployment of modern water-saving plumbing fixtures and appliances, but also to the city’s conservation initiatives. For 2018, Highland Park received a Utility Water Saver Award from the Illinois Section American Water Works Association.

The conservation measures have coincided with a $30 million upgrade of the water plant that switched from a conventional treatment process to membrane ultrafiltration, online since July 2014. That transition brought substantial challenges that, according to Jensen, the 11-member plant team has met successfully.

Sustainable city

Highland Park, north of Chicago on Lake Michigan, is a progressive suburban community with a strong environmental ethic. Eight years ago, the City Council adopted a 20-year Sustainability Strategic Plan that sets specific goals in 10 areas including built environment, community engagement, ecosystems, energy, materials, mobility and, of course, water.

The Illinois Section AWWA has a Water Efficiency Committee, of which Jensen is a member. “That is very important to our city leaders,” says Jensen, who has 37 years’ experience in the water industry. The water plant costs about $2 million a year to operate, and $500,000 of that is for electricity. “Water conservation is a component of energy conservation because so much energy is invested in every gallon of water we produce,” Jensen observes.

One key to the city’s water-saving initiative was the enactment in 2013 of a three-tier water pricing program based on conservation rates. Traditionally, utilities charge large users less per unit volume, “which encourages use and not conservation,” Jensen says. In Highland Park, as consumption increases, the rate goes up.

Lawn sprinkling regulations have also been significant. For many years, the city had watering restrictions based on time of day. “In 2013, the council upped the ante by adding odd-even regulations,” Jenson says. “For example, you can only sprinkle on odd-numbered days of the month if you have an odd street number.”

In addition, new lawn sprinkler systems must have U.S. EPA WaterSense-rated soil moisture sensors so that lawns are not irrigated when the soil is already wet. “And there are folks in town who have stopped sprinkling out of concern for the environment and the realization that they really don’t need to,” Jensen says. “The native grasses here tolerate drought well. They turn yellow and go dormant, but they don’t die. As soon as it rains, they bounce back.”

Applying technology

Technology has a role, too. Over the past few years, the city has converted nearly all water meters to a fixed-network automated meter reading (AMR) system. Along with that, about 600 Leak Spy acoustic devices (Owen Equipment) are deployed on the distribution network to “listen” for leaks. That helps the distribution system team quickly locate leaks that otherwise might not be detected until water found its way to the surface.

“The AMR system also has some great features,” Jensen says. “It will identify suspected leaks in homes based on excessive overnight use, so we can notify the homeowners. By catching those leaks early, we can help people to fix them, and it saves them money because they don’t pay for water that’s just going down the drain.”

In addition, last summer the city launched a customer dashboard (WaterSmart Software) that lets customers track their water use online, compare their consumption to typical conserving and wasteful residents, and see where they fit on that spectrum. All those endeavors are backed up by customer education:

Bill stuffers on topics related to conservation.

Webpages that include links to WaterSense, the Alliance for Water Efficiency and other conservation-oriented sites.

A social media outreach program covering about 20 posts per year on topics like Drinking Water Week, Imagine a Day Without Water, and Smart Irrigation Month.

Jensen is proud of a Water Tower display consisting of 35 5-gallon jugs, arranged in a five-tier pyramid, to illustrate the 175 gallons of water a typical household uses per day. The display is kept at the water plant and is used with school tour groups. It also goes on the road at times, such as to the public library to promote Drinking Water Week. “It’s well-received,” Jensen says. “We have a poster, graphics and pamphlets that go with it.”

Making the water

Because of the water savings, the new water plant has plenty of cushion before reaching its 30 mgd-rated capacity. The plant serves Highland Park and surrounding communities with a combined 60,000 population. It feeds 175 miles of distribution piping, from 30-inch transmission lines going wholesale customers and reservoirs to 6-inch mains. The system is pump-pressurized.

From the time the George B. Prindle plant was built in 1929, it used a conventional process to treat Lake Michigan water. Two factors drove the switch to membrane ultrafiltration. The first was the perceived need in the mid-1990s to increase capacity to handle summer peak demands, and do so on a confined site on “made land” jutting into the lake.

The second and more important driver was the 1993 Cryptosporidium outbreak in Milwaukee, caused by a plume of runoff over that city’s Lake Michigan water intake after a torrential spring rainfall. Highland Park took the position of assuming that Cryptosporidium could be in the lake at any time, and therefore the community needed the best possible protection from it.

“We immediately reduced the standard for turbidity in our finished water, long before the government did,” Jensen says. “We also bought particle counters and turbidimeters for each of our filters long before the government required us to do that.”

Investigation of a plant upgrade began in 1996, at which time membrane ultrafiltration was in its infancy and its cost was prohibitive. The plant’s capacity could have been boosted from 21 to 30 mgd by adding settling plates or tube settlers to the existing settling basins, but that would not have improved the pathogen barrier. “Then we looked at ozone along with it, but we didn’t have the footprint,” Jensen recalls.

By 2002, the cost of membrane filtration had dropped significantly, and the city began pilot-testing and comparing two vendors’ technologies. In the end, the city team chose an ultrafiltration system from Evoqua Water Technologies.

Redundancy built in

The membrane system consists of six trains, each rated at 6 mgd. That means the plant can treat 30 mgd even if one train is out of service. “In summer, the lake can turn very cold,” Jensen says. “When it’s hot and people are using water on their lawns, we can get cold water welling up from the deep lake if the wind direction changes. The viscosity of water increases at colder temperatures, and with a submicron pore size in the membranes, that’s an enormous factor. We designed the worst-case scenario around high demand when the water is about 50 degrees F. So that required more square footage of membrane.” 

The new technology challenged the plant team. “We’re past the steep part of the learning curve, but now we’re at the point where the equipment is showing some signs of age,” Jensen says. “So now we’re starting to experience the maintenance issues associated with this technology. It also requires a different skill set.

“This system is more highly automated. Without the SCADA system, the plant would not be operational. There are hundreds of valves that manage the membrane trains, and that is all choreographed by the SCADA system. We have some talented folks who came to us with skills in troubleshooting, diagnostics and maintenance. Those who didn’t have that background had to pick it up along the way.” The plant team members are:

• Walt Willing, lead operator, 26 years with the city, Class A water operator license.
• Paul Zegan (19 years), Cory Smith (10 years), Chris Cizek, Gale Young, and Randy Curtis, Class A plant operators.
• Henry Peskator (38 years) and Jeremy Hitchmough, plant operators.
• Tyler Rowland, plant mechanic.
• Marianne Evangelista, chemist (10 years).
• Riley Flower, 2018 summer intern.

Stepping right up

With an effective pore size of 0.1 to 0.2 microns, the membrane system provides a positive barrier against the oval-shaped Cryptosporidium oocysts, which measure about 2 by 5 microns. The system runs an automatic membrane integrity test three times a day. “It’s important that we maintain the integrity of that barrier,” Jensen says. “The membranes have been very robust.”

That doesn’t mean the process has been trouble-free. “The conversion was a harrowing experience,” Jensen says. “Our city manager likened it to rebuilding an airplane while in flight. It involved completely rebuilding our electrical system with new transformers and switchgear, new redundant power feeders from the utility, and two new 1.5 MW standby diesel generators (Cummins). We changed over from chlorine gas to sodium hypochlorite as our primary disinfectant out of concern for transporting toxic gas through the community.”

The biggest operating challenge was with the strainers that protect the membranes against sand abrasion. “When we turned the plant on, the lake turbidity was 0.8 NTU,” Jensen says. “But within hours, we weren’t able to produce any water through the membrane system. It turned out the strainers were clogged.”

The problem was sand, silt and clay drawn into the intake during winter storms that stir up the lake bottom. During winter’s low-demand times, flow velocity to the plant was low, allowing the particles to settle in the pipe. Then during high-demand times in summer, the sand grains would be lifted free and make their way to the strainers.  

The solution was to increase the size of the strainer openings and, after winter storms, run the raw water pumps at high speed to scour the material from the intake. The incoming water is then directed to the old flocculation/settling basins, where the particles settle by gravity. The clarified water then can be pumped out and treated. That reduced strainer cleaning labor by 90 percent.

The team also had to deal with water condensing in the air-supply lines to the air-actuated valves in the membrane system. They resolved that by adding desiccant air dryers, adding heat trace and insulation to the air lines, and installing automatic blowoffs to remove water from low points in the lines.

After four years of operations, the major challenges are in the rearview mirror, and Highland Park residents have high assurance that their water — that resource they help conserve — is safe and in reliable supply.

Energy challenge: A trade-off

Highland Park was one of five water utilities enrolled in the Water Utility Energy Challenge, a competition funded by the Great Lakes Protection Fund and managed by the American Water Works Association. The communities competed to see how well they could change their operations to reduce air pollution — especially mercury releases — created by their electricity usage.

Don Jensen, superintendent of water production, says Highland Park qualified for the competition largely because it could supply the sponsors with good operating data from its SCADA system (iFIX and Historian, GE Digital, integrated by Allan ICS). “We have a really great SCADA system and a historical database that is very comprehensive,” Jensen says. “We were able to provide production and energy consumption data going back a year and could continue to provide that data for the year of the competition.”  

The idea was for the competing water utilities to shift their electricity usage from times of day when air pollution from power generation was high (basically overnight when coal-fired power plants are the main electricity sources) to times when pollution was lower (during the day when solar and wind resources are operating). That created a conundrum for Highland Park because historically the utility had tried to shift usage to night hours to take advantage of lower off-peak electricity prices. “It became a trade-off between producing water at times when there was less pollution, or at times when power cost less per kilowatt-hour,” Jensen says. “If we were to do this year-round, I think we’d see higher cost because we’re not able to take advantage of the off-peak rates at night.”

The competition began in April 2017 and covered the succeeding 12 months. Highland Park received recognition as the Technical Leader in the competition.

Ann Arbor, Michigan, won the $20,000 prize as Water Utility Emissions Champion. The city of Bayfield, Wisconsin, won a $10,000 prize as Water Utility Green Champion. Detroit was recognized for the Best Pilot Project, and the Onondaga County Water Authority in North Syracuse, New York, was recognized as Carbon Reduction Leader.

“As I predicted, our limited capability to shift electricity consumption to lower-polluting times of day, when cleaner sources are powering the grid, made competition with the other participating water utilities difficult,” Jensen says. “Nevertheless, this was a valuable endeavor in that we all contributed to the pilot project and helped identify strengths and weakness in the pollution reduction approach and which types and sizes of water systems can most benefit from employing these techniques.”