Responding to changing demands of the marketplace is critical to the success of any business. Treating and distributing water to industrial, commercial and residential customers is no different. When market changes occur, the service provider needs to adapt to meet those changes.
Water demand in southeast Michigan has decreased over the past decade as the population shrank, manufacturing declined, and households installed more efficient appliances that use less water. The end result is that the Detroit Water and Sewerage Department (DWSD) treatment and distribution system is capable of supplying much more water than the service area’s 3.5 million residents use.
Determining the most cost-effective way to adjust operations to meet decreased demand is one of the challenges being addressed in the water master planning process under way at DWSD. Wholesale water customers are participating in the process to help determine what future demand will be and to provide feedback on different alternatives being explored to address excess capacity. It is a difficult change of which DWSD has encouraged wholesale customers to be a part.
DWSD operates five water treatment plants that have a rated capacity of providing 1,720 million gallons (MG) of drinking water each day to the 127 communities served. Peak demand on the hottest day of summer, when the greatest volume of water is being used, has only exceeded 1,000 MG four times in the last ten years, and only once in the last seven years. Furthermore, many communities are managing their peak demand through local storage or ordinances that limit the use of irrigation systems to off-peak hours. Maximum day demand is projected to stay around 1,000 MG through 2035. Closing the 720 MG gap between capacity and demand offers opportunities for savings but also requires careful evaluation.
The network of water treatment plants and piping is complex. Fixed and operational costs are impacted differently by alternative scenarios for repurposing a water treatment plant. Pumping and storage capabilities must be left in place at a repurposed plant to enable continued service to customers served by the plant. New piping must be added to bring treated water from another plant to the repurposed plant’s pump station. In the end, operational savings must be greater than the required capital investment.
Originally, eight repurposing alternatives were considered. The alternatives were evaluated using different cost criteria and discussed at workshops with wholesale customers in June and August. Two of these alternatives that can be undertaken in a two-phase process, are being further evaluated to confirm cost savings are achievable. A set of guiding principles has also been developed to aid in evaluation, based on insights gained about consolidating treatment plants and required safeguards like maintaining three water intakes.
The Water Master Plan is being developed over a two-year period with completion in June 2015. The plan will identify infrastructure needs over the next 20 years for upgrading, improving or decommissioning water treatment, water supply, storage, booster stations and transmission system facilities. Recommendations will be made in 5-year increments. An update on the Water Master Plan will be presented at the October 23, 2014 TAC meeting and a series of wholesale customer workshops will be held in DWSD operational zones beginning in October 2014. Customers will be notified of the upcoming workshop dates by early October.
Source: DWSD
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