AgdaPkt 2014-09-08 Closed and Joint with SA

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7.1.D. - Page 2 ANALYSIS The Unique NO-DES Water Main Flushing System: NO-DES is the Neutral Output Discharge Elimination System for water main flushing, and replaces conventional hydrant flushing programs. Instead of water flowing out of fire hydrants and being wasted, the NO-DES process utilizes a truck mounted pumping, filtering and re-chlorinating system which re-circulates the water within the water distribution system. The NO-DES unit is connected with large hoses between two fire hydrants, which creates a temporary "loop" in the water distribution system. A pump on the unit circulates water at prescribed velocities where it is passed through a series of filters which remove sediment and particulate matter. Disinfectant can be added to further improve water quality and ensure its safety, something current flushing methods cannot achieve. Inline turbidity meters indicate when desired clarity levels are met, making it easier to know when the flushing has achieved its purpose. The result is water conservation, improved water quality, and increased disinfectant residuals. Since very little water is lost with the NO-DES Process, National Pollution Discharge Elimination System (NPDES) issues are eliminated. The NO-DES method: • Saves water that would be wasted using conventional flushing methods • Saves the energy used to produce and pump flushed water • Improves water quality in the distribution system, and solves issues relating to bio-film buildup and nitrification • Cleans and scours the inside of water mains more effectively than conventional flushing techniques • Eliminates storm water discharge issues and fines • Eliminates property damage due to flooding • Eliminates pressure loss and surging (water hammer) that contribute to main breaks and consumer leaks • Enables City to lead by example and encourage water conservation in the community Because of the water and energy savings achieved through use of the NO-DES system, the City will recover the full purchase price of the system in as little as 3.2 years' time. (See chart below). For Redwood City, the NO-DES Water Main Flushing Technology will allow Public Works to properly maintain the water system mains and quality of the drinking water in a sustainable way now and into the future. On average NO-DES has the capability to save the equivalent amount of water that approximately 316 homes in Redwood City would use in one year. The NO-DES method will also reduce administrative costs and limits on flushing due to SWRCB regulations.