1. City of Willits WTP Design and Funding Procurement Update February 24 th City Council Meeting Scott Buecker, P.E.

2. Agenda Background Raw Water Quality Issues Available Pretreatment Technologies Recommended Path Forward Cost Impact Funding Status and Schedule Update

3. Background Water Works Engineers contracted with the City of Willits in September of 2009 for two tasks: 1. Finish the partially completed design of a relocation of the City’s coagulant injection and mixing point: “Phase 1” 2. Design an expansion of the plant from two Siemens Trident Microfloc units to three units: “Phase 2”

4. Background Purpose of both phases is to improve treatment plant performance: turbidity removal turbidity removal manganese precipitate removal manganese precipitate removal Improved treatment efficiency (minimize backwash waste) Improved treatment efficiency (minimize backwash waste)

5. Raw Water Quality Issues: 1.Seasonal spikes in source water turbidity (up to 200 NTU) due to colloidal clay erosion in winter storm events 2.Summer algal blooms during peak demand 3.Manganese oxidation and precipitation throughout the WTP

6. Raw Water Quality Issues: Colloidal Clay Oxidized Manganese Colloidal Algae

7. Phase 1 During the data collection process for Phase 1, WWE realized that relocation of the City’s coagulant injection point would not improve any of the three key issues at the WTP Wrote technical memorandum documenting concerns Accepted by the City, Phase 1 placed on hold

8. How to Resolve WTP Issues WWE has been obtaining data from the City, researching the issues, and corresponding with City staff to develop the most cost-effective solution

9. Treatment of Colloidal Clay How do you treat colloidal clay? Must destabilize charge balance so that it will coagulate and form a settleable floc Must destabilize charge balance so that it will coagulate and form a settleable floc Polyaluminum Chloride (Pro Pac) will do this when given enough time and the right tank configuration Polyaluminum Chloride (Pro Pac) will do this when given enough time and the right tank configuration The existing adsorption clarifiers are not providing enough time or the right configuration The existing adsorption clarifiers are not providing enough time or the right configuration The treatment limits of the Trident Microfloc are 30 to 75 NTU The treatment limits of the Trident Microfloc are 30 to 75 NTU

10. Treatment of Colloidal Algae How do you treat colloidal algae? Pre-oxidation proven to improve algae coagulation and flocculation – KMnO4 in place, is effective at the right dose Pre-oxidation proven to improve algae coagulation and flocculation – KMnO4 in place, is effective at the right dose Destabilize charge balance so that it will coagulate and form a settleable floc Destabilize charge balance so that it will coagulate and form a settleable floc Polyaluminum Chloride (Pro Pac) will do this when given enough time and the right tank configuration Polyaluminum Chloride (Pro Pac) will do this when given enough time and the right tank configuration The existing adsorption clarifiers are not providing enough time or the right configuration The existing adsorption clarifiers are not providing enough time or the right configuration

11. Treatment of Manganese How do you treat Manganese? Oxidize it first to form precipitate Oxidize it first to form precipitate Potassium permanganate oxidation requires less than one minute contact time to oxidize manganese Potassium permanganate oxidation requires less than one minute contact time to oxidize manganese Then destabilize charge balance so that it will coagulate and form a settleable floc Then destabilize charge balance so that it will coagulate and form a settleable floc MnO2 proven to improve flocculation and sedimentation MnO2 proven to improve flocculation and sedimentation Remove the precipitate from the plant to prevent coating of media, fouling of instrumentation, and turbidity spikes Remove the precipitate from the plant to prevent coating of media, fouling of instrumentation, and turbidity spikes

12. Recurring Themes Pre-oxidationCoagulation Settleable floc – How to create? Charge balance (preoxidation and coagulation chemistry) and then create the particle collisions How to create? Charge balance (preoxidation and coagulation chemistry) and then create the particle collisions Provide a quiescent settling zone Provide a quiescent settling zone Solids separation and removal – get the bulk of it out before the existing Trident units

13. Pretreatment Alternatives Coagulation, flocculation and sedimentation processes: Conventional Process – like Ukiah WTP – costly Conventional Process – like Ukiah WTP – costly All in One Processes: All in One Processes: Proprietary Processes – costly and overkill Proprietary Processes – costly and overkill Actiflo, Densadeg, MIEX Actiflo, Densadeg, MIEX Non-proprietary Processes: Non-proprietary Processes: Dissolved Air Flotation – more complex, higher O&M Dissolved Air Flotation – more complex, higher O&M Solids Contact Upflow Clarifier Solids Contact Upflow Clarifier Solids Recirculation Processes Solids Recirculation Processes

14. Solids Contact Upflow Clarifier

15. Original Manufacturer’s Recommendation HS and HSR Clarifier Technology

16. Current Status of Evaluation Current Status of Evaluation Evaluating Solids Contact Upflow Clarifier vs. HSR Clarifiers HSR Treatment Performance Treatment Performance Operational Ease Operational Ease Capital and O&M Cost Capital and O&M Cost

17. Preliminary Results of Evaluation Preliminary Results of Evaluation Capital and O&M Costs are comparable WWE is currently more comfortable with the treatment performance of the Solids Contact Upflow Clarifier and recommends moving forward

18. Recommendations Add a robust pretreatment process as part of the WTP Upgrade and Expansion project, get the bulk of the solids out before Microfloc Cost Impact: $500 to $700K Capital Cost $500 to $700K Capital Cost $31,000 additional engineering cost $31,000 additional engineering cost Assuming SRF funding package will be 80% Grant, 20% Loan, rate impact of pretreatment process is approximately $0.40/connection/month Assuming SRF funding package will be 80% Grant, 20% Loan, rate impact of pretreatment process is approximately $0.40/connection/month

19. Funding Status Update Categorized as either “D” or “E”, both of which will be funded in this year’s cycle Technical Engineering Report and complete application due March 31 st Notice of Application Acceptance (NOAA) in August 2010 Submit Final Plans and Specifications in Fall 2010 SRF Funding Agreement in late 2010 Construction of the upgrade and expansion in summer 2011

20. Other Items Outside of WWE Scope Geotechnical Engineering Structural Engineering Site Surveying California Environmental Quality Act Should be done by Fall 2010 Should be done by Fall 2010