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Molalla Water Treatment Plant Field Trip 4/24/07

Molalla Water Treatment Plant Field Trip 4/24/07. Meet The Molalla Water Treatment Plant Lead Operator: Keith Stiglbauer Started at the plant in 1984 as an assistant operator and was made lead in 1986. Molalla is a city of ~6,000.

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Molalla Water Treatment Plant Field Trip 4/24/07

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  1. Molalla Water Treatment Plant Field Trip 4/24/07

  2. Meet The Molalla Water Treatment Plant Lead Operator: • Keith Stiglbauer • Started at the plant in 1984 as an assistant operator and was made lead in 1986. • Molalla is a city of ~6,000. • Plant is available to treat 4 MGD and presently WTP treats 0.7-2.2 MGD. • This slide show is a virtual tour of how the plant looks today from the remodeled version that took place in 1998.

  3. Collection from the Molalla River. • Sedimentation in Caisson to some degree. • Coagulation and Flocculation for a Microfloc design • (1.5- 8mg/L aluminum chloral hydrate and polymer • .05-0.15 mg/L). • 4’ of plastic beads in Absorption Clarifier to aid in filtering floc. • Filtration with anthracite coal, silica sand, garnet sand, • and garnet gravel (same with old plant). • Soda Ash for pH adjustment (1.2 mg/L). • Sodium Hypochlorite Disinfection 12.5%. Water Treatment Steps

  4. What is novel at this plant? • Small, basic, and understandable process for making clean and safe drinking water. • Has a low ecological footprint • The final product is water that is far below EPA regulations

  5. Site of the 1993 Pump Station that was destroyed in the 1996 flood

  6. Source Intake Process • Water is collected from the bottom of the Molalla River through intake screens that bring in water at a very low velocity. • This avoids bringing in unwanted sediment and oils that float along the surface. An opening in the screen is about the diameter of a toothpick. • To clean the screens compressed air is used once or more daily. • Fish friendly and approved with a $10,000 grant for using these kinds of screens.

  7. Clean out along river.

  8. Source Intake Process • Water is brought into the caisson via a 24” line and then transported through a 18” transmission line from the caisson to the main plant. Caisson 12 feet wide Molalla River 25 feet deep 18 inch diameter pipe

  9. Source Intake Process • Water is then transported through a 24 inch diameter pipe to a Caisson (measuring 25 feet deep and 12 feet wide). • 3 vertical turbine pumps move water up to plant. 100 hp, 75 hp, and 40 hp

  10. Pump Station Before and after 1996 Flood

  11. Rebuilt pump house after 1996 floods, with caisson underneath.

  12. 100 hp, 75 hp, and 40 hp vertical turbine pumps for sending water up to the plant.

  13. Old 2 MGD plant; used in summer or during periods of high turbidity.

  14. New Microfloc Plant 1998 • 2 MGD capacity; usually runs at 1200/gpm when in operation. • Coagulation and Flocculation. • Filtration process. • Disinfection and pH adjustment prior to sending to storage reservoirs. • Very inexpensive process.

  15. Trident Microfloc Water Treatment Plant Flocculation Filtration

  16. Turbidity and Streaming Current Monitor for automatic feeding of coagulant chemicals. • Optimizes Coagulant Chemical Feed

  17. Coagulation Chemicals Aluminum chloral hydrate

  18. Coagulation • Coagulation and Flocculation process. • First rapid mixing of water with Aluminum chloral hydrate. • Addition of non-ionic polymer for flocculation. • Very inexpensive process.

  19. Addition of Coagulant

  20. Polymer added for building floc.

  21. Hydraulic door opens when backwash cycle runs for waste to flow to sludge pond.

  22. Sludge pond for new 2 MGD plant.

  23. Flocculation Micro-Floc Basin

  24. Grate in Clarifier with 4’ of plastic beads underneath that the water has passed up through and leaves some larger floc behind. Upflow Clarifier 4 feet of polymer v

  25. Microfloc Settling

  26. Pinfloc seen with a flashlight in the clarifier portion of a Microfloc type water plant.

  27. Water travels down thru filtration.

  28. Multi Media Filterbed Filtration (same with old plant). anthracite coal silica sand garnet sand garnet gravel 4 ft

  29. Turbidity out usually is below 0.05 ntu State Law Turbidity= 0.3 ntu

  30. Water leaves plant for disinfection and pH adjustment.

  31. Sodium Hypochlorite (bleach) feed room separate from the other chemicals used due to the hazardous nature of this material.

  32. pH adjusted prior to entering distribution system

  33. Backwash pump

  34. Custom Built Software

  35. What is novel at this plant? • Multiple source intake lowers turbidity • Uses state of the art Micro-floc technology • Multi-layered filters. • Gravity feed distribution systems

  36. One of two reservoirs; 1.2 MG and 2.0 MG

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