An In House – Phased Approach for Final Clarifier Rehabilitation

1. An In House – Phased Approach for Final Clarifier Rehabilitation

2. Angel Rivera Superintendent of Mechanical Maintenance

3. History of the Buffalo Sewer Authority • When Buffalo was established as a village, all waste was disposed in adjacent bodies of water. • In the 1890’s, health officials agreed that the pollution to the adjacent bodies of water was responsible for many diseases, most notably, typhoid. • Because of persistent pollution on the Niagara River, Canada and the US entered into a treaty in 1909 to protect boundary waters. “Providing a high level of sanitary benefits to the communities we serve.”

4. History of the Buffalo Sewer Authority Bird Island prior to the construction of the WWTP “Providing a high level of sanitary benefits to the communities we serve.”

5. History of the Buffalo Sewer Authority • In 1935, the New York State Department of Health mandated the City of Buffalo to stop polluting the Niagara River with waste. Because the city was in financial turmoil at the time, a new authority was created – the Buffalo Sewer Authority. • By 1938, the Authority completed its system of intercepting sewers, and built its primary treatment plant on Bird Island where all city sewage was treated. • This start of the art Primary Sewage Treatment Plant: • Removed and incinerated all solid matter. • Chlorinated all liquid matter prior to discharging into the Niagara River “Providing a high level of sanitary benefits to the communities we serve.”

6. History of the Buffalo Sewer Authority Bird Island Primary Treatment Plant in 1938 “Providing a high level of sanitary benefits to the communities we serve.”

7. History of the Buffalo Sewer Authority • With the increasing national awareness of the need to more fully protect our water resources, the State in 1966 directed further improvement of our facilities by providing secondary treatment. • With the help of federal and state grants, secondary treatment facilities were constructed and placed in service by 1981. • Continual process improvements and upgrades • Examples of Major Capital Improvements since 1981 • Fine Bubble Diffuser and Blower Re-rating Project • WWTP SCADA System • New Grit Removal & Disposal System • Sludge Dewatering Centrifuge “Providing a high level of sanitary benefits to the communities we serve.”

8. History of the Buffalo Sewer Authority Bird Island Primary Treatment Plant 1980’s & 90’s “Providing a high level of sanitary benefits to the communities we serve.”

9. Angel RiveraSuperintendent of Mechanical Maintenance • Supervise and coordinate all activities of the Maintenance Department at the Buffalo Sewer Authority’s Bird Island Wastewater Treatment Plant (WWTP). • Responsible for the upkeep and repair of all equipment, utilities, buildings and grounds at the WWTP and eleven (11) Remote Pumping & Metering Stations. • Implemented capital projects totaling over $8 million in a 6 year period, including: • Installation of sludge withdrawal equipment on 16 clarifiers, $2.2 million project. • Cleaning of two large (1 million gallon) anaerobic digesters, $1.7 million project. • Rehabilitation of South Buffalo Pumping Station, $1.5 million project. • Annual Rehabilitation of 3 WWTP Incinerators, $1.2 million in total projects. • Rehabilitation of motors and impellers on three 3000/5000 HP blowers, $900,000 project. • Rehabilitation of 2-550 HP RWWP and 2-1850 HP SWWP Pumps $300,000 • Re-tubing of Natural and Digester Gas Fired Boilers, $150,000 project. • Rehabilitation of Substation and Switchgear, $150,000 in total projects. “Providing a high level of sanitary benefits to the communities we serve.”

10. Final Clarifiers • What’s Their Purpose • Improve Effluent Quality • Provide a means for solids and floatables to separate from the forward flow and be collected • Main Components • Method of Settled Solids Removal • Inlet Arrangements • Method of Scum Removal • Drive Units “Providing a high level of sanitary benefits to the communities we serve.”

11. Final Clarifiers at the Bird Island WWTP- 2001 • Quantity: 16 • Diameter: 130 feet • Depth: 12’ @ Side-Wall, 12.5’ @ Tank Center • Total Average Design Flow: 180 mgd • Total Peak Design Flow: 360 mgd • Type Design: Riser Pipe • OEM: FMC (US Filter / Siemens Water Technology) • Approximate Age: 25 Years (Installed in 1975). “Providing a high level of sanitary benefits to the communities we serve.”

12. Final Clarifiers at the Bird Island WWTP “Providing a high level of sanitary benefits to the communities we serve.”

13. Final Clarifiers at the Bird Island WWTP “Providing a high level of sanitary benefits to the communities we serve.”

14. Rise Pipe Pier Supported Type Clarifier • Diameters larger than 30 feet “Providing a high level of sanitary benefits to the communities we serve.”

15. Riser Pipe Clarifier Sludge Withdrawal Flow “Providing a high level of sanitary benefits to the communities we serve.”

16. Riser Pipe Clarifier Sludge Control Box Riser Pipe Control “Providing a high level of sanitary benefits to the communities we serve.”

17. Final Clarifiers at the Bird Island WWTP “Providing a high level of sanitary benefits to the communities we serve.”

18. Existing Peripheral Feed & Overflow Influent Flow Effluent Waste- water Flow Sludge Box Sludge to Center Drain “Providing a high level of sanitary benefits to the communities we serve.”

19. Existing Peripheral Feed & Overflow Influent Flow Effluent Flow “Providing a high level of sanitary benefits to the communities we serve.”

20. Final Clarifiers at the Bird Island WWTP • 1998 Field Evaluation of Secondary Clarifiers By John Esler, P.E. • Conclusion: • Moderate short circuiting up to a flow of 11 mgd • High sludge blankets and direct short circuiting at higher flows • At all flow rates, high degree of rotational stirring, creating instability at the tank periphery and retarding the inward current • Recommendations: • Reduce rotational rate. • Reconfigure sludge pipes to lay horizontal on collector frame. • Replace variable sized return sludge tubes. • Control individual sludge tube flow in center RAS box with new control valves (“twist turn orifice terminals”). “Providing a high level of sanitary benefits to the communities we serve.”

21. Final Clarifiers at the Bird Island WWTP Drive Unit 24 minutes per revolution Sludge Box Flow Control One of five pipes plugged At least 20% floor not picked up Pipes Create Wall Effect Mass Rotation “Providing a high level of sanitary benefits to the communities we serve.”

22. Final Clarifier Rehabilitation December 2001 • December 2001 • Final Clarifiers 7B & 8B Out of Service Due to Drive Failures and Structural Misalignment. • The Structural Integrity of Truss Arms, Center Cage and Center Pier on both units are in question. • Treatment Plant Maintenance unable to repair units utilizing available parts, supplies and equipment. • US Filter (FMC) brought on site to inspect the condition of the remaining 14 tanks. • Drives on 7 of the remaining 14 tanks in determined to be “marginal” condition (Replacement gap setting >0.375”). “Providing a high level of sanitary benefits to the communities we serve.”

23. Final Clarifier Rehabilitation December 2001 “Providing a high level of sanitary benefits to the communities we serve.”

24. Final Clarifier Rehabilitation December 2001 “Providing a high level of sanitary benefits to the communities we serve.”

25. Final Clarifier Rehabilitation December 2001 “Providing a high level of sanitary benefits to the communities we serve.”

26. Final Clarifier Rehabilitation • Repair of Final Clarifiers 7B & 8B – Choices? • Replace existing drive unit. • Inspect and repair all failed structural components. • High Cost repair with no improvement in performance. • No guarantee that remaining components will not fail in the near future. • Reliability of remaining Final Clarifiers unknown. • Continual high maintenance cost for existing Final Clarifiers • Constant withdrawal tube plugging • Repairing damaged to collector piping, boots, wipers and supports. • Long draining and cleaning time. “Providing a high level of sanitary benefits to the communities we serve.”

27. Proposed Repairs to Final Clarifiers 7B & 8B Use crane to remove bridge & Railing Use crane to remove and replace Center Drive Unit Inspect and repair: Center Pier, Sludge Box and Center Cage. Separate arms from center cage. Inspect and repair structural damage. Repair or replace all damaged piping, boots, wiper blades, piping support. “Providing a high level of sanitary benefits to the communities we serve.”

28. Proposed Repairs to Final Clarifiers 7B & 8B Re-attach and rebalance arms. Adjust and level rotating plane. “Providing a high level of sanitary benefits to the communities we serve.”

29. Final Clarifier Rehabilitation • December 2001 - Meet with US Filter rep to discuss purchase of new Sludge Withdrawal Equipment. • Presented with a proposal for two new Tow-Bro Header Sludge Withdrawal mechanisms, including: • Unitube sludge removal headers and supports • H40Ht Drive Unit w/ Reducer, Motor and Overload • Drive Platform • Center Pier • Skimmer Assembly • Associated Bolts and Anchors • Structural Steel Hot Dip Galvanized “Providing a high level of sanitary benefits to the communities we serve.”

30. Tow-bro Clarifier Design “Providing a high level of sanitary benefits to the communities we serve.”

31. Tow-bro History and Development • Tow-bro developed in 1920’s by Darwin Townsend and James Brower. • Envirex, as Rex Chain Belt, installed the first Tow-Bro in 1929. • Refinements to design resulted in Unitube header developed in 1955 by Envirex • To date over 2500 Tow-Bro clarifiers installed. “Providing a high level of sanitary benefits to the communities we serve.”

32. Tow-Bro Header Peripheral Feed & Overflow “Providing a high level of sanitary benefits to the communities we serve.”

33. Tow-Bro Header Drive Unit 33.3 minutes per revolution Unitube Header with 23 Withdrawal Points Approximate 2’ Horizontal Profile 21” x 21” Manifold Inlet “Providing a high level of sanitary benefits to the communities we serve.”

34. Exiting Riser Pipe Final Clarifiers Sludge Box Largest Inlet Pipe 8” Drive Unit 24 minutes per revolution Only 5 Withdrawal Pipes, Horizontal Pipe Arrangement Approximate 5’ Horizontal Profile Sludge to Center Drain “Providing a high level of sanitary benefits to the communities we serve.”

35. Existing Peripheral Feed & Overflow Influent Flow Effluent Flow “Providing a high level of sanitary benefits to the communities we serve.”

36. Existing Peripheral Feed & Overflow Influent Flow Effluent Flow Sludge Box Sludge to Center Drain “Providing a high level of sanitary benefits to the communities we serve.”

37. Tow Bro H-drive “Providing a high level of sanitary benefits to the communities we serve.”

38. Tow-Bro Strip Liner Drive Unit “Providing a high level of sanitary benefits to the communities we serve.”

39. Riser-pipe Ball Race Bearing Felt Bearing Race Cover 4 pt. Ball Bearing Oil Bath “Providing a high level of sanitary benefits to the communities we serve.”

40. Circular Clarifier Drive UnitsBearing Arrangements 4 Pt. Contact Strip Liner Riser-Pipe Ball Race Bearing (4-Point) Tow-Bro H-Drive Bearing “Providing a high level of sanitary benefits to the communities we serve.”

41. Tow-Bro H-DriveBearing Arrangements • Strip Liner • Split Gear • Field Inspection of bearing • 38 to 42 Rc • Can be rebuilt, in-place, in the field • Low Cost, quick delivery • Keeps working after failure “Providing a high level of sanitary benefits to the communities we serve.”

42. Tow-Bro H-Drive Replaceable Strip Liner Replaceable Strip Liner Main Gear “Providing a high level of sanitary benefits to the communities we serve.”

43. Tow-Bro H-Drive Replaceable Strip Liner • Main Gear Split for On Site Disassembly “Providing a high level of sanitary benefits to the communities we serve.”

44. Riser-Pipe Ball Race Bearing • 4 Point Contact • Higher Hardness • Higher Loads • Factory Repair Only • Requires Crane and Lifting of Bridge • Locks up with Failure “Providing a high level of sanitary benefits to the communities we serve.”

45. Circular Clarifier Drive Units Main Bearing Failures • Condensate, water, produces oxidation, rust • High carbon content of the balls, races oxidize very quickly • Oxidation leads to surface pits • Surface pits lead to stress risers • Stress risers lead to critical shearing stress • Broken balls “Providing a high level of sanitary benefits to the communities we serve.”

46. Circular Clarifier Drive UnitsMain Bearing Arrangements Oil Lubricated “Water Lubricated” “Providing a high level of sanitary benefits to the communities we serve.”

47. Passive Automatic Condensate Drain System • The Drive is Equipped with piping that allows any Condensate that would otherwise accumulate in the main Drive Housing to drain out. • The difference in Specify Gravity between water and lubricating oil used in drive is the principle upon the system functions. • Note: Successful operation of the system depends upon the sequence of filling the drive housing initially and every time periodic maintenance is performed. • Note: Heat Trace required for operation during periods of below freezing temperature. “Providing a high level of sanitary benefits to the communities we serve.”

48. Passive Automatic Condensate Drain System “Providing a high level of sanitary benefits to the communities we serve.”

49. Main Tank Skimmer Assembly Scum Blade Length From Center to Side of Tank “Providing a high level of sanitary benefits to the communities we serve.”

50. Main Tank Skimmer Assembly “Providing a high level of sanitary benefits to the communities we serve.”