1. Visit us at: www.ci.englewood.co.us\wwtp\default.htm

2. K. I. S. S. K KChemical I Injection S System S Simplified

3. Presented by Kirk PetrikKirk Petrik - Project Manager, Brown and Caldwell Darwin BarrieDarwin Barrie - Maintenance Supervisor, Littleton / Englewood WWTP Greg FarmerGreg Farmer - Operations Supervisor, Littleton / Englewood WWTP James WidnerJames Widner - Brown and Caldwell

4. History 1991- Liquid chemical disinfection system replaced gas system Cost - $466,000 Complexity increased through design Temporary system - designed to last 5 years

5. L / E WWTP Action Team RecordsRecords –Operations log entries –Maintenance work orders www.wef.orgwww.wef.org –Discussion forums MeetingsMeetings –Staff interviews BrainstormingBrainstorming –Develop action plan Research

6. Chemical Supplier Experience Tank penetrations / Rigid connectionsTank penetrations / Rigid connections –Minimal below liquid level Connections / valves / fittingsConnections / valves / fittings –Each connection a leak source System replacementSystem replacement –Tank selection critical –Every 5 years Off gassingOff gassing –50% decomposition to gas every 100 days @ 21  C

7. Original Liquid System Chemical isolated in valves and piping Repairs require additional piping, fittings Specialized electronic repair on-site Manifold & Fixed Pump Concept

8. Leakage Result of NaOCl isolation in piping- chemical decomposition

9. Specialized electronic repair

10. Complex Piping How many valves can you count?

11. Complex Control System

12. L/E WWTP System Concept Keep it Simple One Tank + One Pump = One System –Easily isolated –Remove and replace pump- no tools required –Minimal piping and valves –Flexibility/Versatility

13. L/E WWTP System Overview Containment areas

14. Simplified Layout

15. Simplified Piping

16. Sodium bisulfite pumps 110 V outlet Speed indicator / totalizer Simplified Control

17. Simplified Pump Controls Hand - Off - Auto Switch Manual speed control dial 4 - 20 mA input 110 V connection Plug and Play

18. Temporary System

19. Chemical Transfer / Emergency Response Containment drain valve Transfer pump Transfer pump connection

20. Off - Gassing Chlorine gas trapped in line Pressure relieved

21. Pumps & Piping BeforeAfter

22. Pumps Before

23. Pump Controls BeforeAfter

24. System Operation & Control

25. Pump Maintenance 1 2 3 4 Change pump tube as indicated by totalizer: Hypochlorite - every 2 months Bisulfite - every 3 weeks

26. Dosage Control Methods Wet chemistry residual analyzer –Unreliable Hach DPD method –Interference Oxidation Reduction Potential

27. OxidationReductionPotential Oxidation Reduction Potential ORP measures the transfer of electrons –Chlorine forms that are toxic to microorganisms are missing one or more electrons and satisfy their need for electrons by stealing them from organics or other donors through an electrical attraction. This electrical potential is the ORP and is measurable in millivolts (mV) Higher mV = greater disinfecting capability

28. ORP Probe Locations Effluent ORP Influent ORP ORP Controller

29. ORP Controller & Probe Influent ORP Effluent ORP Programming access

30. ChlorinationSetpoint Chlorination Setpoint Select a setpoint that gives the desired fecal kill The setpoint is dependant on the chlorine residual species

31. DechlorinationSetpoint Dechlorination Setpoint Start with a low setpoint to assure compliance Gradually increase setpoint if chemical savings is desired

32. ORP Maintenance Autowash cycle once/dayAutowash cycle once/day –A weak acid solution is pumped to the electrode –A calculated average dosage is maintained while in the wash cycle Manual cleaning twice/weekManual cleaning twice/week –Pull the probe and clean with a toothbrush

33. Auto wash reservoir Manual Probe Cleaning Acid cleaning solution Toothbrush

34. ORP Performance Fecal Coliform 3330 /100ml* Since ORP Installation - 300 / 100 ml Effluent Chlorine Residual 0.003 mg/l Since ORP Installation - 0 Violations * 30 day geometric mean

35. Alternate Control Modes Flow paced modeFlow paced mode –The pump speed is paced by the flow meter Manual modeManual mode –The Pump speed is manually adjusted to maintain the desired ORP mV

36. ORP / Flow Paced Control Choose flow paced or ORP paced pump speed

37. Operational Summary More is not always better Simplicity in design = Simplicity in operation and maintenance Simplicity can increase versatility Chlorination / dechlorination automation can provide reliability

38. Disinfection Alternative Costs

39. The End