Small System Chlorination

1. Small System Chlorination Scott TorpieOffice of Drinking Water Water/Wastewater Operator Workshop March 24, 2010

2. Our Shared Mission To protect the health of the people of Washington Stateby ensuring safeand reliabledrinking water.

3. Session Outline • Questions • PowerPoint presentation • Post test

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. 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

7. Waterborne Disease Outbreaks (U.S. 1971 - 1996) Water sourceTotal outbreaksIllnesses Groundwater 371 (58%) 91,000 Surface water 216 (33%) 470,000 Other 56 (9%) 10,000 Source: EPA Proposed Groundwater Rule

8. Outbreaks on Groundwater Supplies Cause of outbreakTotal Contaminated source1 86% Distribution system 11% Other 3% 1Including untreated, interrupted, or inadequately disinfected ground water Source: Proposed EPA Groundwater Rule

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. 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. 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. 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. Ionization of Chlorine in Water Hypochlorous vs. Hypochlorite 80% “strong stuff” at a pH of 7.0 “Strong stuff” 20% “strong stuff” at a pH of 8.2

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. Sources of Chlorine in Drinking Water • Chlorine gas • Calcium hypochlorite (dry) • Sodium hypochlorite (liquid)

18. Chlorine is an Additive to Drinking Water • All additives require National Sanitation Foundation listing • Exceptions noted in WAC 246-290-200 • NSF Web site: http://www.nsf.org/certified/PwsChemicals

19. Gaschlorination

20. Calcium hypochlorite tablet erosion feed system

21. Sodium hypochlorite injection system Solution Tank Injection lines Feed Pumps

22. Chemical feed pump (diaphragm pump) Pictures courtesy of LMI/Milton Roy

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? HOCl OCl -

25. Methods and StandardsIndustry specifications • American Water Works Association (AWWA) • WA State Department of Transportation

26. Well Disinfection AWWA Standard C654 • 50 ppm chlorine dose • Mix water in the well • Hold 12-24 hours • Discharge portion back into well • Flush well to zero residual • Take at least twocoliform samples from the well

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. Water Main Disinfection AWWA Standard C651 Standard Specifications for Road, Bridge, and Municipal Construction (WA State DOT)

29. Water Main Disinfection Sequence • Prevent entry of contaminants • After installation, flush (2.5 fps) • Chlorinate (one of three methods), reflush • Protect against backflow during testing • Collect coliform samples • Activate water main after test reports

30. Water Main Disinfection Methods • Tablet method • Continuous feed method • Slug dose method

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. Regulatory RequirementsSource 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. 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. 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. References • Chlorine field test kits: • Hach Co. – www.hach.com • Chlorine (Free) Field Test Kit, Model CN-66, Color Disc, 0.1-3.5 mg/L • Lamotte Co. - www.lamotte.com • Chlorine (Free) Field Test Kit, Model SL-MW, Color Slide, 0.1-1.0 mg/L • Chemical feed pumps • Liquid Metronics Inc.- www.lmipumps.com • Pulsatron, Inc. - www.pulsatron.com/pumps

36. Contact Information Scott Torpie Department of Health 16201 E. Indiana Ave. #1500 Spokane Valley, WA 99216 (509) 329-2116 scott.torpie@doh.wa.gov