Replacing Gas Chlorine with Onsite Sodium Hypochlorite Generation

2. Replacing Gas Chlorine with Onsite Sodium Hypochlorite Generation Tim Geraghty, P.E. Division Manager Alliance Water Resources, Inc.

3. Replacing Gas Chlorine with Onsite Sodium Hypochlorite Generation • Goal: help other utility managers decide if changing disinfectants would be worth considering • What made us consider a change • What options we considered • Costs & benefits • Design • Construction

4. Background • Most water treatment facilities use chlorine as their primary disinfectant • Chlorine use became widespread in the early 1900’s • Chlorine has a proven track record • Chlorine gas is a highly hazardous chemical

5. Background • St. Charles County, MO Water Treatment Plant has successfullyused chlorine gas in 1-ton containers as a disinfectant since 1941 • Plant capacity • 8 MGD average • 22 MGD peak

6. Water Treatment Plant, St. Charles County, MO 1940 2013 They don’t build ‘em like they used to

7. Water Treatment Plant 1940 2013 Not much has changed

8. Background • 2005 - Water District purchased the treatment plant • 2012 - Water District completed an overall WTP assessment • Reviewed existing condition of the plant facilities & equipment • Reviewed plant processes • Developed and prioritized a capital improvement plan

9. Background • Results of the plant assessment • Electrical/efficiency upgrades $1.4M • Filter upgrades $2.3M • Booster pump station replacement $4.0M • Replacement of the gas chlorine feed system $2.5M • Lime, ammonia and fluoride system improvements $0.9M • Total $9.7M

10. Why consider changing from chlorine gas? • Need to update existing chemical processes, controls and equipment due to age • Safety • Employees • People in the surrounding community • Environment

11. Why consider changing from chlorine gas? 1997 – one ton container split 25 miles away in Kirkwood, Missouri 2012 – one ton container leaking 10 miles away in Chesterfield, Missouri

12. Why consider changing from chlorine gas? 2002 – leaking 1” hose connected to 90-ton railcar 50 miles away in Festus, Missouri 48,000 pounds released - 63 people injured Pictures from US Chemical Safety & Hazard Investigation Board Report, 2003

13. Why change? Federal OSHA Safety Regulations(TOSHA requirements may be more stringent) • EMPLOYEES • OSHA Process Safety Management (29 CFR 1910.119) • Respirators – fit testing, medical baselines and periodic evaluations • Hot Work • Confined Space • Contractor Safety & Record Keeping • Coordination with LEPC • Management of Change • Chlorine Institute Pamphlet 65 for PPE • Chlorine Institute Pamphlet 155 for water and wastewater operators • Training • Record keeping, record keeping, record keeping

14. Why change? PEOPLE IN THE SURROUNDING COMMUNITY • US EPA Risk Management (in section 112(r) of the Clean Air Act) • Worst case release scenario • Alternative release scenarios • Offsite consequence analysis • Estimating offsite receptors • Hazard reviews • Operating procedures • Compliance Audits • Mechanical integrity • Employee participation • Coordinating with LEPC • Communication with the Public • Regular re-submittals Federal Safety Regulations - EPA

15. Why change? • Water Plant • Missouri Conservation Department -Wildlife Area • US Army -Training Area • University Research Area • (added political pressure from regulators) Protect the Environment

16. To decide if a disinfectant change was worthwhile, we reviewed our goals and other disinfectants

17. Review of Alternatives - Requirementsfor disinfection • Groundwater Rule • 4-log removal of viruses • Chlorine contact time • Effects of chlorination on pH • Distribution system bacteria re-growth potential • THM’s/HAA’s • Nitrate formation • Chlorite formation Water Quality Considerations

18. Criteria • Safety • Life Cycle Costs • Capital • O&M labor • Power • Chemicals • Waste treatment/hauling • Chemical & power cost stability • Chemical strength stability • Chemical availability Review of Alternatives - Selection Criteria

19. Review of Alternatives - Criteria • Need for additional treatment • Level of automation • Permitting issues • Space requirements • Operational flexibility, familiarity & simplicity • Equipment reliability Selection Criteria

20. Review of Alternatives • Gas chlorine • Ozone • Ultraviolet (UV) Light • Chlorine dioxide • Hypochlorite • Calcium hypochlorite • Sodium hypochlorite • Onsite hypochlorite generation • Bulk deliveries • Combinations of the above

21. Review of Alternatives • Gas Chlorine in 1-ton containers (current practice) • Advantages – low capital and operating cost, simple operation, low maintenance • Disadvantages – hazardous and toxic chemical, potential of leaks &high level of regulation

22. Review of Alternatives • Gas Chlorine in 150-pound cylinders • Advantages – low capital and operating cost, simple operation, low maintenance • Disadvantages – hazardous and toxic chemical, potential of leaks &high level of regulation • Switching to smaller cylinders would reduce the quantity released during a major leak, but more changeovers & handling would be required

23. Ozone • Expensive • Additional disinfectant needed for maintaining residual in distribution • Often used to eliminate a specific contaminant • Ultraviolet (UV) Light • Additional disinfectant needed for maintaining residual in distribution • Often used to eliminate a specific contaminant Review of Alternatives

24. Review of Alternatives • Chlorine dioxide • Strong disinfectant • Stops THM formation • May require additional treatment for chlorite • Often used for pre-treatment – not as the lone disinfectant

25. Review of Alternatives • Bulk Sodium Hypochlorite (typically 12.5% solution) • Advantages – Low capital cost, generally safer than chlorine gas • Disadvantages – High operating cost, degradation, corrosive health hazard

26. Review of Alternatives • Generated Sodium Hypochlorite (0.8% solution) • Advantages – no storage of highly hazardous chemicals, consistent product concentration • Disadvantages – High capital cost, hydrogen gas byproduct, short product storage time

27. Review of Alternatives Process Schematic Bulk hypochlorite components Onsite hypochlorite generation components

28. 0 0 4 2 0 1 Hazardous to Environment, Users, and Community Chlorine Gas Bulk Sodium Hypochlorite (11 - 15%) NFPA Rating Health = 4 Flammability = 0 Instability = 0 Oxidizer Health = Lethal Short Term Exposure = Burns, Chest Pain, Emotional Disturbances, Lung Damage, Death Physical Hazards = Containers may rupture or explode. NFPA Rating Health = 2 Flammability = 0 Instability = 1 Oxidizer Health = Intense or continued exposure could cause temporary incapacitation or residual injury. Instability = Can become unstable at elevated temperatures and pressures. OX OX

29. 0 1 0 Environmentally Benign 0.45% Generated FAC or 0.8% Generated FAC NaCl (SALT) NFPA Rating Health = 1 Flammability = 0 Instability = 0 Health = Exposure may cause mild irritation Instability = Normally stable, even under fire conditions. NFPA Rating Health = 1 Flammability = 0 Instability = 0 Health = Exposure may cause mild irritation Instability = Normally stable, even under fire conditions. 0 1 0

30. Review of Alternatives Of these alternatives, only gas chlorine requires PSM & RMP programs

31. Review of Alternatives • Cost savings due to eliminating PSM training and administration • 60 training hours annually for operators & maintenance staff • 200 hours annually for contractor training • 100 hours annually for administration per year • training reports, maintenance reports, PSM Manual updates, PSM and RMP annual SOP certifications, periodic resubmission of PSM and RMP documentation, internal compliance audits, testing of chlorine sensors, … • $10,000 - $15,000 per year

32. Review of Alternatives • UV and Ozone were ruled out - high costs + additional need for residual disinfectant • For the two hypochlorite alternatives, onsite generation preferred because of lower O&M • Chosen Alternative: Onsite Generation of Sodium Hypochlorite because of reduced safety concerns; estimated additional cost of treated water less than $0.04 per 1,000 gallons (<1% of user rate)

33. Design Considerations • First step – choose a hypochlorite generator manufacturer • Equipment varies by manufacturer • Major considerations • Safety considerations • Ease of operation/number of components • Equipment footprint • Life cycle costs • Availability

34. Design Considerations • Choosing a hypochlorite generator manufacturer • The cost of materials varies by manufacturer but one pound of chlorine is generated by roughly: • 15 gallons soft water (at 15-40 gpm and about 60 psi) • 3 pounds salt • 2 kilowatt-hours

35. Design Considerations – Site Visits • Designers and operators visited several installations of various manufacturers

36. Design Considerations • Efficiency & Complexity • Indoor Equipment (generators, blowers, power and control panels) • Room arrangement/ available space • HVAC requirements & equipment heat loss • Outdoor Equipment (tanks & accessories) • Sunshades

37. Design Considerations • Sodium Hypochlorite Storage Tanks • Storage time • Degradation (esp. for 12.5%) • Sodium Hypochlorite Metering Pumps • Based on each feed point’s chlorine demand • Sized for both 12.5% and 0.8% solution

38. Design Considerations • Standby Options • Standby generator • Provisions for bulk delivery • Plant Shutdown (generally available at this location September through May)

39. Capital Costs • Equipment Bids • ChlorTec (two 750 ppd units)$ 536,500 • MIOX (three 500 ppd units) $ 572,980 • PSI (two 800 ppd units) $ 619,500 • Construction Bids (includes equipment) • Engineer’s final estimate $2,041,000 • Low of 5 bids: • KCI Construction $2,213,500

40. Chosen Alternative - MIOX • Simplicity / fewest components • Smallest footprint / able to fit most equipment in the existing building

41. Design Considerations for Chosen Alternative • System Control Panel Inputs • Water hardness • Brine tank level • Storage Tank Level • System Components • Brine pump • Generators/rectifiers • Hydrogen dilution blowers • Sodium hypochlorite storage tank level

42. Chosen Alternative - MIOX

43. Construction • Construction Sequence • Site work • Install outdoor hypochlorite tanks • Install new process piping and metering pumps • Place bulk hypochlorite (12.5%) system in operation • Remove existing gas chlorine piping and equipment • Install hypochlorite generators in the space vacated by the gas chlorine system

44. Construction • Schedule and current progress • Site work completed (relocated storm & sanitary sewers) • Bulk tanks, piping, water softeners, pumps and dilution panel installed

45. Construction • Schedule and current progress • SOP’s written and operators trained in bulk chemical feed process • Bulk chemical (12.5%) and tanks being put in operation next week • Remaining work to be completed by July 2013 • Remove existing gas chlorination system • Install hypochlorite generation and other equipment inside the building and start-up

46. Key Points • Ultimately, the Water District Board decided that increasing the level of safety was worth the additional capital and O&M costs • Our chosen disinfection alternative was not the lowest cost alternative • The chosen manufacturer’s equipment was not the lowest cost alternative • Involving the operators in the decision-making was critical and strongly influenced the decision • The operators (and probably their spouses) can’t wait for the workplace to be safer

47. Special Thanks to Black & Veatch and Parkson Disinfection for technical information they provided for the presentation For More Information • Tim Geraghty, P.E. • Division Manager • Alliance Water Resources • 100 Water Drive • O’Fallon, MO 63368 • 636-561-3737 x101 • tgeraghty@alliancewater.com • www.alliancewater.com