TO: Mayor and Commissioners
FROM: John Morgan, Director of Environmental Services Department
THROUGH: Donald B. Cooper, City Manager
DATE: May 17, 2016
Title
Service Authorization No. 12-21 to Kimley Horn and Associates, Inc. in the amount of $123,269.00 for professional services in performing a study of the water distribution system to address chlorine residual depletion.
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Recommended Action:
Recommendation
Motion to Approve Service Authorization No. 12-21 to Kimley Horn and Associates, Inc. in the amount of $123,269.00 for providing professional engineering services in performing a analysis and study of the water distribution system to address chlorine residual depletion.
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Background:
As part of maintaining the water quality throughout the distribution and transmission system as mandated by state and local health regulations, the utility’s division routinely performs sampling for chlorine residuals along with lead and copper, enhanced disinfection cycles, flushing of fire hydrants, and injection of free chlorine from remote booster stations.
Chlorine has been widely used in the water treatment process for disinfection. Free chlorine may cause the formation of disinfection byproducts (DBPs), which are chemical, organic and inorganic substances that can form during a reaction of a disinfectant with naturally present organic matter in the water. DBPs may potentially be harmful to human health. Ammonia is added to the water to prevent the formation of disinfectant by-products beyond regulated limits. The addition of ammonia forms chloramines, which are less likely to form DBPs. Ammonia can also be a food source for the initiation of biological growth which then depletes any free chlorine, leaving more ammonia to accelerate the cycle of chlorine depletion. This situation may be further compounded by areas/neighborhoods within the distribution system that exhibit low flow rates, allowing more time for organic growth from stagnation, esp...
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