1. Reducing THM via Aeration: A Case Study November 21, 2013 by Gary Williams, P.E. Jones & Henry Engineers Southeast AWWA District Meeting 1

2. Agenda  Location  History  Pilot  Implementation  Take Away Information 2

3. Location Map 3

4. Distribution System Map 4

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6. Water Quality 2008 Raw Water Total Hardness285 mg/L as CaCO 3 Total Alkalinity133 mg/L as CaCO 3 pH8.2 Turbidity3.2 Total Organic Carbon4.5 mg/L Finished Water Total Hardness150 mg/L as CaCO 3 Total Alkalinity36 mg/L as CaCO 3 pH9.2 Total Organic Carbon (average)2.1 mg/L TOC Removal (average)51% 6

7. THM 2008 7

8. Water History  1972 Water Treatment Plant, Low Head Dam, and Reservoir Constructed  1993 Water Treatment Plant Study  1996 Reservoir Study  1999-2000 Water Treatment Plant Expansion $3,000,000  2002 Second Reservoir $2,300,000  2004 Water Distribution System DBP Reduction Study  2005 Chlorine Dioxide Benchtop Study  2005 MIEX Benchtop Study  2006 RSSCT for GAC Benchtop Study  2008 THM Reduction via Aeration Opflow Article 8

9. 2008 THM Reduction via Aeration Opflow Article 9

10. Research  Limited Research Available for Dynamic System  One Company Marketed a System $$$$$$$$  Air : Water Ratios (cfm : gpm) 5 to 60  If A:W = 40 and processing water @ 700 gpm = 28,000 cfm blower  Approximately 200 hp Blower 10

11. Pilot  Assumed 20:1 A:W ratio or 14,000 cfm  Determined Approximate Area Diffusors for 14,000 cfm in Clearwell 2  Assumed One/half Depth of Clearwell or 7 feet  Calculated the Volume over the Diffusors  Developed the Detention Times in the Three Celled Clearwell  Influent Cell60 minutes  Aeration Cell75 minutes  Effluent Cell60 minutes  Scaled down the flows of air and water to match a 4-inch PVC pipe 11

12. Pilot 12

13. Test Pipe Arrangement Pilot Air Requirements Air: Water RatioRequired (cfm) Total Air (cf) 2:10.1 9.5 5:10.25 23.8 10:10.5 47.5 20:11.0 95 13

14. Pilot Protocol  Two Pilot Steps  First Step Test Entire A:W Range  Second Step Optimize Results of the First Step  Goal was to Optimize Air Required  Parameters Tested  TOC  THM  HAA5  Chlorine Residual  Stability pH Total Alkalinity Total Hardness Calcium Hardness TDS Chlorides Sulphates 14

15. Pilot Results Air: WaterAir Rate Trihalomethane Results (ug/L) Ratio(scfm)October 14November 11 ControlN/A47.138.0 2:10.1016.916.7 5:10.255.79.0 7:10.35N/A6.7 10:10.502.15.7 20:11.002.7 30:11.502.6 40:12.003.0 50:12.502.1 15

16. Pilot Results 16

17. Other Pilot Results TemperatureOctober 16 deg CNovember 12 deg C Control Sample (no aeration) TTHM Initial – 52.6 ug/LFinish – 47.1 ug/L pHInitial – 9.3Aerated – 7.9 Cl 2 Free mg/LInitial – 2.13Aerated – 1.96 Cl 2 Total mg/LInitial – 2.45Aerated – 1.19 @ A:W ratio > 10:1 CHBrCl 2, CHBr 2 Cl, CHB 3 below Detectable Limit 17

18. Project Costs  Aeration System 5:1 A:W ratio 3,500 scfm Blower Stainless Steel Diffusors Caustic Soda Feed System to increase pH to 8.9 12-inch Air Piping to Clearwell Diffusors Electric and Controls  Project Cost - $401,700  Annual O&M - $73,000  GAC System  Project Cost - $1,225,600  Annual O&M - $145,000 18

19. Brand X  2011 SolarBee Aeration System Proposal Two 15 HP Blowers 580 scfm Each Three Submersible Mixers 86 Diffusor Assemblies Caustic Soda Feed System to increase pH to 8.9 8-inch Air Piping to Clearwell Diffusors Electric and Controls  Project Cost - $571,700  Annual O&M - $21,000  SolarBee Offer  Install Clearwell Equipment  Provide Temporary Blower and Piping  6-month Trial  If Satisfied, Purchase Price $360,000 19

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21. Second Thoughts  April 1, 2012 SolarBee Oops Further Testing Showed Spray Aeration Preferable Highly Recommended Spray System One GS-12 Submersible Mixer in Clearwell 1 Two SN-15 Floating 15 HP Pump/Mixer/Spray Systems Two Ventilation 2HP Blowers 750 scfm Each Caustic Soda Feed System to increase pH to 8.9 12-inch Air Piping to Clearwell Electric and Controls  Project Cost - $369,900  Annual O&M - $22,000  SolarBee Offer  Provide In-Clearwell Equipment and Two Blowers  Install Clearwell Equipment  6-month Trial  If Satisfied, Purchase Price $168,000 21

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23. Schedule  Bid – October 2012  Preconstruction Meeting – November 2012  Substantial Completion – March 2013  Total Completion – June 2013 23

24. TTHM Summary 24 Sample Date Water Temp (deg C) Clearwell 1 Effluent Clearwell 2 Effluent DS202 (Max TTHM) % Removal In Clearwell #2 Regrowth in System 4/3/2013729.618.431.838%13.4 5/6/20131547.220.443.457%23.0 5/20/20131856.224.864.756%39.9 6/17/20132262.721.262.366%41.1 7/1/20132463.230.764.751%34.0 8/13/20132353.320.352.162%31.8 9/9/20132056.020.552.663%32.1 Note: Baffle wall opening sealed on 4/12/2013 (all values TTHM in ppb, except where noted)

25. Maximum Residence Time Running Annual Average 25

26. Take Away Information 1. THMs Have to be Formed  Aeration Does Not Reduce Formation Potential 2. Chloroform is Typical Target THM 3. Powered Air Supply for Ventilation Probably Required 4. Check pH/Stability 5. Check Chlorine Residual 26