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Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking.

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Presentation on theme: "Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking."— Presentation transcript:

1 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water Small System Chlorination Scott Torpie Office of Drinking Water Water/Wastewater Operator Workshop March 24, 2010

2 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 2 Our Shared Mission To protect the health of the people of Washington State by ensuring safe and reliable drinking water.

3 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 3 Session Outline  Questions  PowerPoint presentation  Post test

4 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 4 Presentation Themes  Historical context for chlorination of public drinking water supplies  Mechanics of chlorine disinfection  Methods and standards for chlorination  Regulatory requirements for chlorination

5 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 5 Historical Context for Chlorination Chlorination begins (U.S.)  Jersey City, N.J. was first U.S. utility to use chlorine (1908)  Cases of typhoid, as well as other diseases dropped dramatically following the use of chlorine

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7 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 7 Waterborne Disease Outbreaks (U.S ) Water source Total outbreaks Illnesses Groundwater 371 (58%) 91,000 Surface water 216 (33%) 470,000 Other 56 (9%) 10,000 Source: EPA Proposed Groundwater Rule

8 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 8 Outbreaks on Groundwater Supplies Cause of outbreakTotal Contaminated source 1 86% Distribution system 11% Other 3% 1 Including untreated, interrupted, or inadequately disinfected ground water Source: Proposed EPA Groundwater Rule

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11 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 11 Chlorination Mechanics How well does chlorine work? Bacteria: Penetrates cell wall and kills the organism Viruses: Relatively effective inactivation Giardia: Relatively ineffective inactivation Cryptosporidium: Used alone, chlorine has no effect

12 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 12 What Interferes With the Disinfection Process?  High pH  Low water temperature  Turbidity  Insufficient mixing  Presence of chlorine-demanding compounds, such as iron or manganese

13 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 13 Chlorine treatment standards: “C x T” T = time water is in contact with the chlorine C = concentration of free chlorine (mg/l), measured after “T” Need C x T = 6 for groundwater 0.3 mg/l for 20 min. same as 0.6 mg/l for 10 min.

14 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 14 Chlorine Chemistry Total = Free chlorine + Combined chlorine Free chlorine: hypochlorous acid + hypochlorite ion Combined chlorine (chloramines): chlorine combined with ammonia or organic nitrogen (causes chlorine taste and odor)

15 15 Ionization of Chlorine in Water Hypochlorous vs. Hypochlorite 80% “strong stuff” at a pH of % “strong stuff” at a pH of 8.2 “Strong stuff”

16 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 16 Chlorine Demand and Chlorine Residual Demand - Inherent properties of the water that consume chlorine Residual - What’s left after the chlorine demand has been satisfied, remaining available to act against microorganisms

17 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 17 Sources of Chlorine in Drinking Water  Chlorine gas  Calcium hypochlorite (dry)  Sodium hypochlorite (liquid)

18 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 18 Chlorine is an Additive to Drinking Water  All additives require National Sanitation Foundation listing  Exceptions noted in WAC  NSF Web site:

19 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 19 Gas chlorination

20 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 20 Calcium hypochlorite tablet erosion feed system

21 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 21 Sodium hypochlorite injection system Solution Tank Feed Pumps Injection lines

22 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 22 Chemical feed pump (diaphragm pump) Pictures courtesy of LMI/Milton Roy

23 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 23 Disinfection By-Products (DBP) Formation  Surface water - can have high levels of organic compounds that help produce DBPs  Groundwater - generally very low in organic DBP precursors, low levels of DBPs are generally produced

24 What Happens to Chlorine After it’s Added to Water? Cl2 Oxidizes organic acids (making DPBs) Reacts with organic nitrogen (making Chloramines = Combined Chlorine) Oxidizes inorganics (e.g. Iron and Manganese) Free Chlorine 24 HOCl OCl -

25 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 25 Methods and Standards Industry specifications  American Water Works Association (AWWA)  WA State Department of Transportation

26 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 26 Well Disinfection AWWA Standard C ppm chlorine dose 2. Mix water in the well 3. Hold hours 4. Discharge portion back into well 5. Flush well to zero residual 6. Take at least two coliform samples from the well

27 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 27 Reservoir Disinfection AWWA Standard C652  Method 1 - full reservoir dosed to yield 10 ppm after 6 hours  Method 2 - empty reservoir interior sprayed with 200 ppm solution. Contact time = 30 min.  Method 3 - reservoir dosed to yield 2 ppm after 24 hours

28 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 28 Water Main Disinfection  AWWA Standard C651  Standard Specifications for Road, Bridge, and Municipal Construction (WA State DOT)

29 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 29 Water Main Disinfection Sequence 1. Prevent entry of contaminants 2. After installation, flush (2.5 fps) 3. Chlorinate (one of three methods), reflush 4. Protect against backflow during testing 5. Collect coliform samples 6. Activate water main after test reports

30 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 30 Water Main Disinfection Methods  Tablet method  Continuous feed method  Slug dose method

31 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 31 When to Apply Shock Chlorination:  Bacteriological contamination  Vandalism  Broken water main  Cross connection incident  System depressurization  Starting up a well after extended inactivity

32 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 32 Regulatory Requirements Source Treatment  Surface water or GWI  Fecal indicators in source water  Unaddressed sanitary survey deficiencies  Hydraulic connection with surface water  Sanitary control area threats  Coliform in source water

33 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 33 Regulatory Requirements Distribution System Treatment  When using a phosphate compound (for sequestration, corrosion control)  When coliform water quality monitoring history measured from the distribution system is repeatedly unsatisfactory

34 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 34 Regulatory Requirements A purveyor MAY NOT CHLORINATE:  When doing so creates unrepresentative conditions in the distribution system at the time of collecting routine coliform samples  Between report of a unsatisfactory routine coliform sample and collection of all repeat coliform samples (unless specifically approved by DOH)

35 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 35 References  Chlorine field test kits:  Hach Co. – Chlorine (Free) Field Test Kit, Model CN-66, Color Disc, mg/L  Lamotte Co. - Chlorine (Free) Field Test Kit, Model SL-MW, Color Slide, mg/L  Chemical feed pumps  Liquid Metronics Inc.-  Pulsatron, Inc. -

36 Public Health - Always Working for a Safer and Healthier Washington Washington State Department of Health Division of Environmental HealthOffice of Drinking Water 36 Contact Information Scott Torpie Department of Health E. Indiana Ave. #1500 Spokane Valley, WA (509)


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