1300 W MARINE VIEW DR 2018-01-19

SECTION 7-09.3(24) OF THE STANDARD SPECIFICATIONS IS DELETED AND REPLACED WITH THE FOLLOWING: 7-09.3(24) Flushing and Disinfection of Water Mains Before being placed in service, all new water mains, or extensions to existing mains shall be flushed, disinfected with a chlorine solution, and satisfactory coliform bacteria test reports obtained. The Contractor shall submit his procedure(s) for flushing and disinfection in accordance with this section. At minimum, the submittal shall include: the location of all taps and other appurtenances to be used for chlorination and/or flushing purposes, the location of the sample collection taps- the disposal location and treatment procedure for all chlorinated water discharged from the mains; and the procedure for disinfection including application method, point of application, and target concentrations for the contact interval to be used. 7-09.3(24)A Flushing Sections of pipe to be disinfected shall first be flushed to remove any solids or contaminated material that may have become lodged in the pipe. If no hydrant is installed at the end of the main, then a tap sufficient to provide a flush velocity inside the main of at least 2.5 fps shall be provided. At a minimum, the flush shall discharge one entire pipe volume of water from the new main. Flushing shall continue as long as material or color is visible in the discharge. Taps and other appurtenances required by the Contractor for temporary release of air, chlorination, or flushing purposes shall be provided by the Contractor as a part of the construction of water mains. To-protect aquatic life in receiving waters, the Contractor shall be responsible for disposal of all chlorinated water flushed from mains and shall neutralize the chlorine contained in the wastewater before disposal into any natural drainage channel (or feature draining to a natural channel). The Contractor shall be responsible for disposing of disinfecting solutions to the satisfaction of the City of Everett and the Washington Department of Ecology. If approved by the Engineer, disposal may be made to any available sanitary sewer, provided the rate of disposal will not overload the sewer. When flushing following the repair of a main break, and the main segment containing the repaired section cannot be hydraulically isolated to the nearest hydrant, the Contractor shall install a 2-inch tap and gate valve at the repaired section to provide for proper flushing. 7-09.3(24)B Disinfectant Concentration and Retention Period (Contact Interval) Before being placed into service, all new mains and repaired portions of, or extensions to, existing mains shall be disinfected so that a free chlorine residual of not less than 10 mg/1 remains in the disinfectant solution after standing 24 hours in the pipe. The initial free- chlorine residual concentration of disinfectant solution shall be not less than 25 mg/l. Disinfectant chlorine solution contact time may be reduced from 24 to 12 hours if an initial disinfectant concentration of 50 mg/L is used. Disinfectant concentrations greater ? than 50 mg/L shall not be used. The ending concentration of an initial 50 mg/L solution following a 12 hour contact time shall also be not less than 10 mg/L. Hydrostatic pressure testing of the new main shall be conducted prior to the main undergoing disinfection. 7-09.3(24)C Form of Applied Chlorine Disinfection of water mains shall only be performed using the continuous feed method employing liquid J hypochlorite solutions (liquid calcium hypochlorite or liquid sodium hypochlorite). Dry calcium hypochlorite shall not be used. Gaseous chlorine(also known as liquid chlorine)shall not be used. r t I Except for Everett's prohibition on the use of dry calcium hypochlorite or gaseous chlorine, disinfection shall follow the continuous feed methods specified in the most recent version of AWWA Standard C-651 and Section 7-09.3(24)of these Specifications. UP3220-Div_7 Page SP 7-7r June 15,2005 �a