2. Replacing Gas Chlorine with Onsite Sodium Hypochlorite Generation
Tim Geraghty, P.E.
Division Manager
Alliance Water Resources, Inc.
Introduce topic. Discuss my education and 24 yrs experience in design, construction and operation of water systems.

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 successfully used 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
Discuss plant’s history
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
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. 48,000 pounds released - 63 people injured
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
Coordination with LEPC
OSHA Process Safety Management (29 CFR )
Management of Change
Chlorine Institute Pamphlet 65 for PPE
Respirators – fit testing, medical baselines and periodic evaluations
Chlorine Institute Pamphlet 155 for water and wastewater operators
Hot Work
Confined Space
Training
Contractor Safety & Record Keeping
Record keeping, record keeping, record keeping

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

15. Protect the Environment
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 - Water Quality Considerations
Requirements for 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. Review of Alternatives - Selection 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 - Selection 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. Review of Alternatives
Ozone
Expensive
Additional disinfectant needed for maintaining residual in distribution
Often used to eliminate a specific contaminant
Ultraviolet (UV) Light
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. Bulk Sodium Hypochlorite (11 - 15%)
Hazardous to Environment, Users, and Community
Chlorine Gas
Bulk Sodium Hypochlorite ( %)
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. 4
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. 2 1 OX OX
MIOX Proprietary and Confidential- DO NOT DISTRIBUTE

29. 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. 1 1
MIOX Proprietary and Confidential- DO NOT DISTRIBUTE

30. Review of Alternatives
Comparison
Capital Cost
Annual O&M
Hazard Potential*
Chlorine Gas (add scrubber & other controls)
$900,000
$50,000
highly hazardous gas
Ozone
High
limited UV
low
Bulk Sodium Hypochlorite
$650,000
$160,000
highly corrosive liquid
Generated Sodium Hypochlorite
$1,900,000
$100,000
hydrogen gas by-product
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 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 Construction Bids (includes equipment)
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. For More Information www.alliancewater.com Tim Geraghty, P.E.
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
x101