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SECTION 5100 WATER MAIN DISINFECTION Revision 7 – September 2020 Page 1 of 6 PART 1 GENERAL 1.1 SCOPE: A. This section includes the materials, equipment, procedures, and requirements to disinfect new and repaired water mains to acceptable levels as provided by the State of Oregon Health Division and City Ordinance. These specifications apply whether constructed as new development or under contract to the City. B. City Engineer shall mean City Engineer or a designated representative. 1.2 BACKGROUND: City of Woodburn Ore. water source is groundwater from the French Prairie Aquifer. The groundwater is then treated to remove iron, manganese, arsenic, radon, and post chlorinated using a hypochlorite solution to produce chloramines. The average residual of 1 to 1.8 ppm of total chlorine is maintained in the distribution system. 1.3 REFERENCE STANDARDS: A. All work will meet the requirements set-forth herein and comply with Oregon Administrative Rule (OAR) 333-61-050, and AWWA C651.92, or latest revision. B. In the event of conflicts between specifications this is the order of precedence: 1. These specifications 2. The direction of the City Engineer 3. OAR 333 4. AWWA C651 (Latest revision) 1.4 CONTRACTOR/DEVELOPER’S RESPOSIBILITY A. The contractor shall furnish properly trained personal, appropriate equipment and materials, and transportation for disinfection of the water mains. B. The Contractor shall submit a disinfection plan (see section 3.1 thru 3.4) including, but not limited to: 1. Proposed schedule 2. Method of charging and equipment to be used. 3. Number and location of sample ports. 4. Disposal of chlorinated water after contact period. 5. Name and contact information for the responsible person on site. C. The Contractor shall give a minimum of three day notice before beginning the disinfection process. D. It is helpful to have the plan reviewed prior to construction to minimize misunderstandings as to the number and location of sample/injection taps. ---PAGE BREAK--- SECTION 5100 WATER MAIN DISINFECTION Revision 7 – September 2020 Page 2 of 6 PART 2 PRODUCTS 2.1 CHLORINE: A. Two forms of chlorine disinfection product will be allowed in city water mains: 1. SODIUM HYPOCHLORITE - Sodium hypochlorite conforming to ANSI/AWWA B300, in pre-mixed solution, 12.5% available chlorine by weight and 87.5% inert material. Solution shall be contained in approved container and clearly marked by the manufacturer including date solution was prepared, form of the solution, and total weight by volume of chlorine. 2. CALCIUM HYPOCHLORITE - Calcium hypochlorite conforming to ANSI/AWWA B300, in granular form or pre-mixed solution. Solution shall be contained in approved container and clearly marked by the manufacturer including date solution was prepared, form of solution, and total weight by volume of chlorine. Calcium hypochlorite shall be 65% available chlorine by weight. The 2.2 PUMPING EQUIPMENT: A. Any pump used for injection of disinfection solution shall be clean, operational, well maintained and for the single purpose of injecting chlorine into potable water systems. B. The Contractor shall know in advance what the pumping rate of the pump is against an average city system pressure of 55-psi. 2.3 HYDRANT WRENCH: A. Fire hydrants shall only be opened and closed using standard hydrant wrenches. Pipe wrenches, crescent wrenches and/or other types of wrenches are strictly forbidden. 2.4 IN-LINE CONTROL VALVES: A. In-line control valves, connecting directly to city system, shall be operated with an approved gate valve wrench. Under no circumstances shall Contractor operate valves without an agent of the city present. B. Contractor shall ensure that only one valve be opened to or from the city main at a time and that all valves have been returned to the closed position before vacating the site for the day. 2.5 DISINFECTION DOSING AND MIXING RESERVOIR: A. Any mixing/dosing reservoir shall be inspected and approved by the City Engineer and shall be clean and free of debris that, in the opinion of the Engineer, presents a risk to the disinfection operations. 2.6 WATER SUPPLY: ---PAGE BREAK--- SECTION 5100 WATER MAIN DISINFECTION Revision 7 – September 2020 Page 3 of 6 A. The Contractor shall make necessary arrangements for providing disinfection operations water such as: mixing granulated chlorine in the dosing reservoir and cleaning. B. Live Fire hydrants shall be operated under the direct supervision of the City Personnel. 2.7 SAMPLING POINTS: A. Sampling points shall be per Standard Detail No.5100-2 of the Standard Specifications, or similar, to slow the flow and create an even stream for sampling and provide protection from surrounding contaminants. Sampling from the direct discharge of a ball valve is unacceptable. B. Sample ports can be connected to either sampling/injection taps or service taps, Details 5100-1 and 5000-4 respectively. Sampling from blow-offs or fire hydrants is unacceptable. C. Saddles shall not be allowed in tapping operations, unless approved by the City Engineer. D. Upon acceptance of new water lines temporary sampling taps and assemblies will be removed by City personnel. Materials may be returned to the contractor if requested. PART 3 EXECUTION 3.1 INITIAL FLUSHING: A. Prior to disinfection operations all lines shall be flushed at a minimum of 2.0 fps and a maximum velocity of 10.0 fps. to a minimum of 2 volume exchanges. The Contractor will make provisions to quantify the flow rates and times required to completely flush newly installed lines. B. Prior to flushing operations the Contractor shall plan, and the City Engineer shall approve, how a given system shall be flushed and sequence in which valves will be operated and times required to flush each leg of the system. E. During flushing operations fire hydrants shall be fully opened and flows shall be controlled, if necessary, by the in-line control valve at connection to existing city main. F. When flushing is complete all fire hydrants shall be closed and fire hydrant control valves left fully open. 3.2 DISINFECTION: A. Prior to disinfection operations the Contractor shall plan, and the City Engineer shall approve, how a given system shall be disinfected and sequence in which valves will be operated and times required to charge each leg of the system. B. Install an injection point, see Detail 5000-1, adjacent to the valve connecting the new water ---PAGE BREAK--- SECTION 5100 WATER MAIN DISINFECTION Revision 7 – September 2020 Page 4 of 6 main to the existing city water supply on the new main side of the valve. C. Disinfection will be accomplished by continuous feed method, defined as follows: 1. Sodium hypochlorite is recommended alternative to calcium hypochlorite though calcium hypochlorite is acceptable. 2. The dosing rate shall be a enough to obtain a minimum of 50 ppm at each sample point. The Engineer will sample the solution to ensure rate has been accomplished. Each sampling point will be checked along the pipeline to ensure that strength is at the minimum of 50 ppm. 3. If the dosing reservoir is of insufficient size as to require mixing of additional batches all subsequent batches shall be mixed at the same dosage rate. A second reservoir shall be set-up adjacent to the primary reservoir so as to ensure a continuous operation. 4. As the chlorinated water flows past fittings, valves, service lines, and hydrants, they shall be thoroughly operated so as to disinfect appurtenances and pipe branches. 5. Minimum contact time shall be 24 hours. The Engineer, in the presence of the Contractor, shall test at each sampling point a minimum of 24 hours after completion of the chlorination operation. Chlorine residual shall be a minimum of 10 ppm. If at this point there is not a residual of 10 ppm in the line at each sampling point the line shall be flushed and steps 1 -5 shall be repeated. 3.3 FINAL FLUSHING: A. After required contact time has elapsed and all the requirements of subsection 3.2 have been met the heavily chlorinated water shall be flushed from newly installed lines. Flushing shall continue until the chlorine residual is measured at or about 1.5 ppm. B. Flushing of water mains shall not be allowed after the ambient temperature reaches 850 F without the prior approval of the Engineer. C. The environment into which the chlorinated water is to be discharged shall be inspected. If there is any possibility that chlorinated discharge will cause damage to the environment, one of the following procedures, as directed by the City Engineer, shall be accomplished. 1. FLUSH TO EXISTING SANITARY SEWER SYSTEM - Heavily chlorinated water shall be flushed into the nearest sanitary sewer manhole. The City will provide, to the Contractor, a hose and diffuser, which shall be installed at the direction of the City Engineer. 2. REMOVAL BY TANKER TRUCK - In the event that a manhole is not within a reasonable distance Contractor shall provide a tanker truck which shall act as a receptacle for flushed chlorinated water then transported to the nearest sanitary sewer and deposited. Tanker shall equipped with a backflow prevention device or ---PAGE BREAK--- SECTION 5100 WATER MAIN DISINFECTION Revision 7 – September 2020 Page 5 of 6 an approved air gap shall be employed. 3. DECHLORINATION – If approved by the City Engineer, heavily chlorinated water may be dechlorinated and discharged to any location mutually acceptable to the Engineer and the Contractor. The method and location shall be submitted a minimum of three days prior to the discharge and approved by the City Engineer. D. During flushing operations the fire hydrant valve shall be fully opened and the flow shall be controlled by the in-line control valve. 3.4 SAMPLING: A. Samples shall be taken within 2 ft. of the connection to the existing City water system. B. Sample shall be taken within 2 ft. of the end of each leg greater than 5 ft. such as a fire hydrant or blow off. Temporary sample taps for fire hydrants legs shall be between the fire hydrant control valve and the fire hydrant. Temporary samples taps at blow offs shall be on the main side of the gate valve. C. Samples shall be taken at other points in the system as instructed by the City Engineer to include a minimum of 200 ft. and a maximum of 500 ft. along a continuous section of pipe. 3.5 SERVICE LINES: A. Service lines as well as all valves, fire hydrants, sampling ports, etc. shall be chlorinated in accordance with these specifications. 3.6 MEASUREMENT AND PAYMENT: A. Payment will be paid per the unit price indicated in the Bid. PART 4 TESTING 4.1 GENERAL: A. After final flushing a sample set shall be tested by a certified laboratory in accordance with subsection 4.3 herein. 4.2 SAMPLE SET: A. A sample set is the total of individual samples taken on a project at the rate of one for each sample point. ---PAGE BREAK--- SECTION 5100 WATER MAIN DISINFECTION Revision 7 – September 2020 Page 6 of 6 B. Two consecutive sample sets shall be taken and pass lab test before the line shall be accepted and put in service. 4.3 SCHEDULE OF SAMPLING: A. Contractor shall notify the Engineer 48-hours in advance of the time he proposes to schedule sampling operations and indicate the lab doing the testing. B. The first sample set shall be taken at or about 48-hours after final flushing is accomplished and the second sample set shall be taken a minimum of 72-hours after final flushing. There must be a minimum of 24 hours between sample sets. 4.4 TESTING PROCEDURES: A. The samples shall be collected by the Contactor or a designee and witnessed by a representative of the City then transported to a State of Oregon certified laboratory for testing. Each of the second set shall be custody sealed by the City immediately after collection prior to transport to the lab. B. The Lab shall be notified by the City to not test samples that the custody seal has been tampered with. B. Samples shall be taken only at approved sample points, no samples will be allowed at fire hydrants or hoses. C. Samples shall be placed and transported in, a sterile bottles treated with sodium thiosulfate as required by Standard Methods for the Examination of Water and Wastewater. D. Samples in a given sample set shall be tested in conformance with approved State of Oregon test methods for microbiological analysis of coliform. E. Sample set must show no coliform (total coliform and E.coli) presence at all sample points. The Contractor shall supply an original signed copy or carbon copy of the satisfactory test results to the City Engineer. F. If testing confirms coliform presence the system shall be completely flushed and re- disinfection repeating the aforementioned procedure. G. When samples are satisfactory and all other applicable installation standards are complied with, the City will then assume responsibility for the new main. H. Additional testing may be required by the City prior to allowing the line to be placed in service. END OF SECTION