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CITY OF EVERETT SPECIAL PROVISIONS I <br /> • Disposal location and treatment procedure for chlorinated water discharged <br /> I <br /> from the mains, and <br /> • Procedure for disinfection including application method, point of application, <br /> and target concentrations for the contact interval being used. <br /> I <br /> 7-09.3(24)A Flushing <br /> Flush sections of pipe being disinfected to remove solids that may have become <br /> lodged in the pipe. Provide a tap sufficient to provide a flush velocity inside the main <br /> of at least 2.5 fps if no hydrant is installed at the end of the main. Flush as long as <br /> material or color is visible in the discharge. Flush at a minimum one full pipe volume <br /> of water from the section of new main being tested. I <br /> Guidelines for Required Flow and Openings to Flush Pipelines <br /> (assumes 40 psi residual pressure in watermain) <br /> Pipe Dia. Flow Required Size of Tap (in) Number of <br /> (in.) to Produce 2.5 2 1/2" Hydrant <br /> fps (approx) outlets <br /> Velocity in Main 1 1 1/2 2 <br /> 1 <br /> (gpm) (in) (in) (in) <br /> 4 100 1 1 <br /> 6 200 1 1 <br /> 8 400 2 1 1 <br /> 10 600 3 2 1 <br /> 12 900 2 2 <br /> 16 1,600 4 2 <br /> Guidelines for Watermain Volume <br /> Inside Dia. Volume per 100 LF <br /> (in) (gal) <br /> 4 65 I <br /> 6 147 <br /> 8 261 <br /> 10 408 <br /> 12 587 <br /> 20 1,632 I Provide taps and other appurtenances required for temporary release of air, <br /> chlorination, or flushing purposes as a part of the Work. <br /> To protect aquatic life in receiving waters, neutralize the chlorine contained in the <br /> I <br /> discharge water before disposing into a natural drainage channel or feature draining <br /> to a natural channel. Dispose of disinfecting solutions to the satisfaction of the City <br /> of Everett and the Washington Department of Ecology. Discharge water disposal <br /> may be directed to an available sanitary sewer, if approved by the Engineer and <br /> provided the rate of disposal will not overload the sewer. <br /> 7-09.3(24)B Disinfectant Concentration and Retention Period (Contact <br /> Interval) <br /> Provide disinfection concentration necessary to obtain a free chlorine residual of <br /> not less than 10 mg/I remaining in the disinfectant solution after a 24 hour contact <br /> time. Provide the initial free chlorine residual concentration of disinfectant solution <br /> not less than 25 mg/I. Contractor may reduce disinfectant chlorine solution contact <br /> time from 24 to 12 hours by using an initial disinfectant concentration of 50 mg/I. <br /> 1 <br /> Maximum allowable disinfectant concentration shall be 50 mg/I. The ending <br /> Watermain Replacement"U" Division 7—STORM, SEWER,WATER October 1, 2019 I <br /> WO No.—UP3698 SP—179 <br />