City of Willits WTP Design and Funding Procurement Update

1. City of WillitsWTP Design and Funding Procurement Update February 24th 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 • manganese precipitate removal • Improved treatment efficiency (minimize backwash waste)

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

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

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 settleablefloc • 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 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 • Destabilize charge balance so that it will coagulate and form a settleablefloc • 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

11. Treatment of Manganese • How do you treat Manganese? • Oxidize it first to form precipitate • 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 settleablefloc • MnO2 proven to improve flocculation and sedimentation • Remove the precipitate from the plant to prevent coating of media, fouling of instrumentation, and turbidity spikes

12. Recurring Themes • Pre-oxidation • Coagulation • Settleablefloc – • How to create? Charge balance (preoxidation and coagulation chemistry) and then create the particle collisions • 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 • All in One Processes: • Proprietary Processes – costly and overkill • Actiflo, Densadeg, MIEX • Non-proprietary Processes: • Dissolved Air Flotation – more complex, higher O&M • Solids Contact Upflow Clarifier • Solids Recirculation Processes

14. Solids Contact Upflow Clarifier

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

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

17. 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 • $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

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 31st • 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