Thomco Construction Inc. 6/14/2021

CITY OF EVERETT SPECIAL PROVISIONS 7-09.3(24)E Preventing Reverse Flow ' Provide a State Department of Health approved backflow preventer installed in the connecting line before making a connection between the existing distribution system and water lines constructed under this Contract that have not been flushed, disinfected, and tested. Install backflow preventer upstream of temporary fill hoses and disinfectant injection equipment. 7-09.3(24)F Chlorinating Valves, Hydrants, and Appurtenances 1 Operate valves, hydrants, and other appurtenances during the disinfectant contact interval for newly-laid pipe while filling the pipeline with the disinfectant chlorine solution and the main is under normal operating pressure. Normal operating pressure is the pressure the existing distribution system provides through the temporary backflow protection device. 7-09.3(24)G Chlorinating Connections to Existing Water Mains and Water Service Connections Chlorinate connections to existing water mains in accordance with the following sections of the most recent revision of AWWA Standard C651: Section 4.6 - Final Connections to Existing Mains, Section 4.7 - Disinfectant Procedures When Cutting Into or Repairing Existing Mains, and Section 4.8 - Special Procedures for Caulked Tapping Tees Swab the internal surfaces of closure fittings with a 5 to 6 percent chlorine solution that can be found in liquid household sodium hypochlorite bleach. 7-09.3(24)H Final Flushing and Testing Notify the City Utilities Division, Environmental Monitoring and Compliance (EMC) staff at least five business days prior to requiring EMC staff to collect samples and measure the chlorine concentration of the disinfectant solution placed in the new main. EMC staff will collect and measure samples at the start and at the end of the disinfectant contact period. Provide sample taps as noted in 7-09.3(24)1 to allow EMC staff to collect at least one set of disinfectant concentration, coliform bacteria and free chlorine samples from both ends of new mains, at the end(s) of each cross or branch, and every 1200 feet along the main. Notify EMC staff at least five business days prior to requiring having EMC staff collect final coliform bacteria and free chlorine residual samples. The City of Everett EMC staff will collect bacteriological and disinfectant residual samples for submitting to Washington State Department of Health, Drinking Water Division certified laboratory for testing. EMC staff will immediately notify Contractor and Engineer upon receiving analysis results. Upon receiving passing test results, flush disinfectant solution from the newly-laid mains until the replacement water throughout the length of the main tests having a level of free chlorine residual representative of the distribution system water supply. 7-09.3(24)1 Sample Collection Taps Provide water sample collection taps at each required sampling location in accordance with COE Standard Drawing No. 526 and as described in these Special Provisions. Locate the end of each water sample collection tap above existing ground level. Plumb taps to provide downward water flow to allow effective filling of sample containers. City EMC staff shall have the authority to refuse to conduct sampling from taps they consider inadequate or not representative of water main quality. Water Main Replacement"V" Division 7—STORM,SEWER,WATER April, 2021 WO No.—UP3730 SP—178 ADDENDUM#1