LTC 408-2019 Water Distribution System RedundancyPUBLIC WORKS DEPARTMENT
408-2019
NO. LTC#
LETTER TO COMMISSION
TO: Mayor Dan Gelber and Members of the Cit Commission
FROM: Jimmy L. Morales, City Manager r
DATE: July 18, 2019
SUBJECT: Water Distribution System Redundancy
In light of recent events regarding service outages of municipal water supply, the following LTC
was prepared to describe the redundancy of the water distribution system serving the City of
Miami Beach.
One of the core responsibilities of the City is to provide adequate infrastructure that supports the
everyday lives of our residents, business owners, and visitors. The provision of safe and reliable
potable water is a fundamental component of fulfilling this responsibility. In order to accomplish
this objective, the City purchases finished water from the Miami -Dade Water and Sewer
Department through four separate metered connections. The water is then transmitted via our
water distribution system to the customers' service lines, where the water is metered and
provided for consumption. The main feed connections for the City are enumerated below. A map
of these interconnects is provided in the attached page.
• One 30 -inch diameter main on the North Bay (79th Street) Causeway
• One 36 -inch diameter main on the Julia Tuttle Causeway
• One 36 -inch diameter main on the Venetian Causeway
• One 20 -inch diameter main on the MacArthur Causeway
Water distribution systems are typically designed as manifolded networks. These networks are
comprised of grids of water mains with the larger transmission lines tied into the smaller
distribution lines. By manifolding the distribution systems, engineers and operators not only
prevent stagnant water issues but also incorporate redundancy into the system's design. Miami
Beach's water distribution system is manifolded in the manner described above.
Widespread water outages, caused by distribution system failures, typically occur due to a lack
of redundancy at major transmission lines. In the case of Miami Beach, the network is manifolded
in a manner that a transmission line break within the City should not precipitate a Citywide water
outage. Additionally, the City does not own or operate a treatment plant, thus eliminating the risk
of a single raw water main from breaking within the City limits.
While the City's system is constructed in a manner that reduces severe risks from within, it is
important to note that isolated areas within the City may experience outages due to water main
breaks. Additionally, Miami Beach relies solely on the Miami -Dade Water and Sewer Department
for our drinking water. Catastrophic failures in the county's system may have significant impacts
on the City's ability to provide water service. These catastrophic failures can create outages that
may affect large portions of the City.
1
In an effort to mitigate possible outages, the Public Works Department maintains ground water
storage tanks with a combined 12 million gallons of capacity. This capacity equates to
approximately half a day of the city's average demand. However, in the event of a crisis, the
ground storage tanks may be regulated to provide essential potable water for longer periods.
Should you have any questions regarding the City's utilities, please do not hesitate to contact
Public Works Director Roy Coley at 305-673-7080.
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Figure 2-1
Water Supply Interconnects from MDWASD
City of Miami Beach Water and Sewer Renewal and Replacement Report