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City of Willits WTP Design and Funding Procurement Update. February 24 th City Council Meeting Scott Buecker , P.E. Agenda. Background Raw Water Quality Issues Available Pretreatment Technologies Recommended Path Forward Cost Impact Funding Status and Schedule Update. Background. - PowerPoint PPT Presentation
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City of WillitsWTP Design and Funding
Procurement Update
February 24th City Council MeetingScott Buecker, P.E.
AgendaBackgroundRaw Water Quality IssuesAvailable Pretreatment TechnologiesRecommended Path ForwardCost ImpactFunding Status and Schedule Update
BackgroundWater 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”
BackgroundPurpose of both phases is to improve treatment plant performance: turbidity removal manganese precipitate removal Improved treatment efficiency
(minimize backwash waste)
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 demand3. Manganese oxidation and precipitation
throughout the WTP
Raw Water Quality Issues:
Colloidal Clay
Oxidized Manganese
Colloidal Algae
Phase 1During 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 WTPWrote technical memorandum documenting concernsAccepted by the City, Phase 1 placed on hold
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
Treatment of Colloidal ClayHow do you treat colloidal clay? 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 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
Treatment of Colloidal AlgaeHow 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 settleable floc 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
Treatment of ManganeseHow 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 settleable floc MnO2 proven to improve flocculation and sedimentation
Remove the precipitate from the plant to prevent coating of media, fouling of instrumentation, and turbidity spikes
Recurring ThemesPre-oxidationCoagulationSettleable floc – How to create? Charge balance (preoxidation and
coagulation chemistry) and then create the particle collisions
Provide a quiescent settling zoneSolids separation and removal – get the bulk of it out before the existing Trident units
Pretreatment AlternativesCoagulation, 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
Solids Contact Upflow Clarifier
Original Manufacturer’s Recommendation
HS and HSR Clarifier Technology
Current Status of EvaluationEvaluating Solids Contact Upflow Clarifier vs. HSR Clarifiers HSR Treatment Performance Operational Ease Capital and O&M Cost
Preliminary Results of EvaluationCapital and O&M Costs are comparableWWE is currently more comfortable with the treatment performance of the Solids Contact Upflow Clarifier and recommends moving forward
RecommendationsAdd 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
Funding Status UpdateCategorized as either “D” or “E”, both of which will be funded in this year’s cycleTechnical Engineering Report and complete application due March 31st
Notice of Application Acceptance (NOAA) in August 2010Submit Final Plans and Specifications in Fall 2010SRF Funding Agreement in late 2010Construction of the upgrade and expansion in summer 2011
Other Items Outside of WWE Scope
Geotechnical EngineeringStructural EngineeringSite SurveyingCalifornia Environmental Quality Act Should be done by Fall 2010