Thomco Construction Inc. 6/14/2021

CITY OF EVERETT SPECIAL PROVISIONS Guidelines for Water Main Volume ' Inside Dia.(in) Volume per 100 LF (gal) ' 4 65 6 147 8 261 10 408 ' 12 587 20 1,632 Provide taps and other appurtenances required for temporary release of air, chlorination, or flushing purposes as a part of the Work. To protect aquatic life in receiving waters, neutralize the chlorine contained in the discharge water before disposing into a natural drainage channel or feature draining to a natural channel. Dispose of disinfecting solutions to the satisfaction of the City of Everett and the Washington Department of Ecology. Discharge water disposal may be directed to an available sanitary sewer, if approved by the Engineer and provided the rate of disposal will not overload the sewer. 7-09.3(24)B Disinfectant Concentration and Retention Period (Contact ' Interval) Provide disinfection concentration necessary to obtain a free chlorine residual of not less than 10 mg/1 remaining in the disinfectant solution after a 24 hour contact ' time. Provide the initial free chlorine residual concentration of disinfectant solution not less than 25 mg/I. Contractor may reduce disinfectant chlorine solution contact time from 24 to 12 hours by using an initial disinfectant concentration of 50 mg/I. Maximum allowable disinfectant concentration shall be 50 mg/I. The ending concentration of an initial 50 mg/I solution following a 12 hour contact time shall be not less than 10 mg/I. ' 7-09.3(24)C Form of Applied Chlorine Perform disinfection of water mains using the continuous feed method employing either liquid calcium hypochlorite or liquid sodium hypochlorite solutions. Dry ' calcium hypochlorite and gaseous or liquid chlorine is not allowed. Follow the continuous feed methods specified in the most recent version of AWWA Standard C-651 and Section 5-15 of the latest edition of the City of Everett "Design and Construction Standards and Specifications for Development", except for the City's prohibition on the use of dry calcium hypochlorite or gaseous chlorine. 7-09.3(24)D Point of Application ' Whenever possible, use the beginning of the pipeline extension, or a valved section of it, as the point of application for the disinfectant solution. Provide a tap to supply water for delivering the disinfectant solution on the pressure, or upstream, side of the valve controlling the flow into the pipeline extension, but downstream of the backflow preventer used to isolate the new main from the existing water distribution system. Obtain Engineer approval in writing to use alternate points of applications. ' For a City allowed direct tie-in to an existing main via an in-line backflow preventer and with the approval of the Inspector, the point of application may be through a corporation stop inserted in the horizontal axis of the pipe. Locate tap within 10- feet of where the line is tied into the existing system. Swab the internal surfaces of the backflow preventer and adjacent downstream appurtenances, valves or couplings for example, with straight hypochlorite solution prior to their installation. Water Main Replacement"V" Division 7-STORM,SEWER,WATER April, 2021 WO No.-UP3730 SP-177 ADDENDUM#1