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, especially during off season. To assist the utilities division in addressing the fine balance of maintaining the regulatory mandated chlorine residual, while maintaining disinfected by-products limits within the water distribution system, staff has requested the services from one of our consultants.
Services to be provided by Kimley Horn and Associates, Inc. (KHA) will include evaluation of the existing distribution system’s hydraulics, as well as the existing chlorine and ammonia injection facilities, to allow the generation of applicable recommendations to the City’s Utility division. In addition, the injection systems will be thoroughly evaluated and examined for flow rates and location of injection for the specific type of chemical (ammonia); the water model will be updated and examined to run scenarios for determining areas of water age; bench testing and analysis of the formation of disinfection by-products as it relates to free chlorine in order to maintain compliance with regulated limits; conducting trial runs of the hydraulic modeling utilizing anticipated enhancements; and an analysis of the use and operations of the remote chlorine booster stations. Total cost for Service Authorization #12-21 is $123,269.
This Service Authorization with Kimley Horn and Associates, Inc. is based on a two-year General Consulting Services Agreement (RFQ #12-06) awarded by the City in January 2012, which has been renewed through January 2017.
The recommendation for award is in compliance with Code of Ordinances, Chapter 36, Section 36.02(A)(2), Method of Acquisitions/ Request for Proposals, Request for Qualifications, Request for Letters of Interest, which have been renewed per Section 36.07(A)(3), Termination, Extensions, and Renewals/ Renewals.
Negotiations regarding the number of hours relating to the scope of service were finalized in a Sunshine Meeting on April 19, 2016.
City Attorney Review:
Approved as to form and legal sufficiency.
Finance Department Review:
Finance recommends approval.
Funding Source:
Funding is available from account 442-5178-536-31.90, Water and Sewer Renewal and Replacement Fund/ Professional Services.