You can never have too much water, right?
If you’ve ever designed, operated or worked for a municipality, you understand the importance of water storage. We need storage to meet peak demands. Our public depends on stored water in the case of emergencies. Our fire departments depend on it. The list goes on and on.
Based on all these needs, too much storage isn’t possible, right? You would expect that was the case. But in actuality, too much is possible. In my many years as a consultant, my clients typically needed additional storage to keep pace with growing demand. Yet projects did come across my desk which did indeed have too much storage.
Detention times in the system are critical when planning storage capacity and also comes into play for water main sizing. Holding the water in the system for too long may lead to a myriad of unfortunate problems including taste and odor issues, buildup of disinfection byproducts (DBPs) and the challenges of maintaining required chlorine residual in remote system areas.
Municipalities play a continuous balancing act to maintain sufficient storage, while maintaining water quality and adequate system pressures. The problems associated with this balancing act are multiplied when there are widely fluctuating seasonal demands on available water. This particularly affects resort communities.
Like anything else, there are always some good options in the tool box. For example, municipalities have flushing programs, loop their distribution systems whenever possible, and/or operate tanks at a lower level during lower season demands to reduce detention times in their systems. The last option may be problematic if system pressure depends upon the tank, especially if already be on the lean side. Active mixing systems are often integrated into storage tanks to encourage more efficient turnover.
With all the challenges faced by municipalities, effective planning, well-conceived design and efficient operations go a long way toward paving the path to a healthy water system.
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