In the heart of the Great Lakes Region, water is in plentiful supply. But that doesn’t mean that it’s cheap. Delivering water to businesses and homes is a costly endeavor. The dwindling number of residents in southeast Michigan, the Rust Belt’s hardest hit region, combined with recession’s economic hardship spurred many communities to find ways to reduce water usage.
In a paper they delivered at the American Water Works Association’s national conference, ACE11, in June 2011, OHMers Carrie Cox, PE, and Vyto Kaunelis, PE, share case studies of how several southeast Michigan communities successfully trimmed costs by managing their water usage.
They describe three different approaches used by municipalities:
• peak shifting
• system optimization
• storage increases
The Back Story
Much like other regional systems with ample water supply, the water system in metropolitan Detroit was designed based on historical high usage, with conservative safety factors. Modern conveniences like automatic irrigation systems have driven peak usage upward. Rather than continuously upgrade systems to meet a demand that might not hold, the Detroit Water and Sewerage Department, wholesale water service supplier to 86 metro Detroit communities, opted for a new approach. DWSD let its customers choose the level of service they wanted to pay for. Communities and water authorities could specify annual volumes, maximum day and peak hour rates in their service contracts.
With the desired level of service was established, the communities had to figure out how to keep water usage below the thresholds, or pay costly penalties in the form of peak usage rates. The City of Troy and the City of Novi both opted to use peak shifting to change their citizens’ water consumption habits.
Peak shifting, the process of moving existing loads to off-peak periods, is commonly practiced in other parts of the US, but less so in the water-rich Midwest. Escalating infrastructure costs, shrinking population and diminishing economic base are forces that made peak shifting a desirable practice here as well.
Peak Shifting Results
The City of Troy reduced its peak water usage by 30% in the three years since it implemented a mandatory grass water ordinance that required odd/even grass watering and prevented irrigation between the peak usage hours of 6am and 10am. Interestingly, the unpopularity of the ordinance drive wide and frequent news coverage, which led to increased public awareness of the new rules.
The City of Novi opted to pursue an aggressive public education plan, rather than an ordinance, sending flyers and information to all its water customers. Those with billing questions were also given information on the benefits of odd/even grass watering and very early morning sprinkler settings. Two years into the education campaign, peak hour factors were down by 28%.
Want more water management success stories? Stay tuned! In the next post, we’ll look at system optimization to manage water usage.