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Home My WebLink AboutPresentation_Regular_11/13/2025Water Treatment Master Plan November 13, 2025 Village of Tequesta Council Meeting Overview Next Steps•Treatment Alternatives for PFAS•Wellfield Testing by utilities staff•PFAS Regulation Summary•Plant SummaryRaw Water Supply & Water • Raw Water Supply Floridan Aquifer Water Plant Summary Floridan Aquifer, 4 wells Surficial Aquifer, 10 wells Raw Water Source:BlendFiltered 2.73 MGDMembrane3.6 MGDCurrent Treatment6.33 MGD Treatment Process Pump to customers•Transfer to Storage•ammoniaDisinfection w/ chlorine and •Degasification of RO permeate•effective for O&M-Filter plant cost•stabilizationBlend minimizes chemical use for •RO:Surficial60:40 –70:30 •Historical blend flows vary• PFAS Regulation PFAS Strong bond, persistent•Chain of linked carbon and fluorine atoms•Firefighting foam (PFOS)•stick items-non–Consumer products •Manufactured chemicals dating back to the 1930s•“Forever Chemical”– PFAS Thousands of PFAS contaminants identified, not all measurable•29 PFAS contaminants of concern in UCMR5•Six PFAS contaminants of concern for regulatory compliance•Highly sensitive•EPA Method 533 and 537.1•1 drop of water in 20 Olympic sized swimming pools•1 inch in 16 million miles•1 grain of salt in 10 million gallons of water•Equivalent to •Measured in parts per trillion (ppt)• PFAS Regulatory Timeline PFAS Regulations Chemicals)GenxDA (commonly referred to as -HFPOPFBSPFHxSPFNA1.0 (unitless) Hazard Index1.0 (unitless) Hazard IndexPFOSZero4.0 pptPFOAZerong/L)4.0 parts per trillion (also expressed as CompoundProposed MCLGProposed MCL (enforceable levels) PFAS Regulations Chemicals)GenxDA (commonly referred to as -HFPOPFBSPFHxSPFNA1.0 (unitless) Hazard Index1.0 (unitless) Hazard IndexPFOSZero4.0 pptPFOAZerong/L)4.0 parts per trillion (also expressed as CompoundProposed MCLGProposed MCL (enforceable levels) Wellfield Testing SAS Wellfield Raw Water PFAS Sampling Well Site #PFOA (ppt)PFOS (ppt)PFHxS (ppt)PFNA (ppt)Hazard Index (unitless) Well 714366.23.61.22 Well 8132852.20.94 Well 188.8295.32.10.97 Well 1916435.12.81.01 Well 208.81831.90.69 Well 2320445.73.41.14 Well 241.41.40.350.380.15 Well 2525439.155.051.70 Well 2635285.9510.81.91 Well 2719187.821.24 EPA MCL4410101.00 Preliminary Review Approach Reviewing demand projections•Determine potential future compliance challenges•Review blend percentages•weighted concentration-Develop flow•Review SAS PFAS concentrations• PFAS VOT WTP Anticipated Blended Water Quality groundwater is necessary to provide regulatory complianceblend rate must be minimized and/or a treatment of SAS Takeaway: SAS Blend Percentage Compound (ppt or ng/L) ↓ 5.00%9.66%10.00%20.00%30.00%40.00% hexafluoropropylene oxide dimer acid, HFPO-DA 1.311.331.331.361.391.42 (GenX) *perfluorobutanesulfonic acid, 2.212.692.723.764.795.82 (PFBS) (C4) *perfluorohexanesulfonic acid 0.981.201.221.712.202.69 PFHxS (C6) *perfluorononanoic acid 2.012.112.112.332.542.75 PFNA (C9) *perfluorooctanesulfonic acid 2.643.994.096.989.8712.75 PFOS (C8) *perfluorooctanoic acid 1.742.552.614.356.097.82 PFOA (C8) Hazard Index Value0.440.480.480.560.640.72 Surficial Treatment Options for PFAS Nanofiltration Carbon (GAC)Granular Activated Ion Exchange Floridan Aquifer Treatment Option Reverse Osmosis (RO) Current Efforts Surficial Well Operational Matrix•Surficial Well 28•RO Concentrate Permit Renewal•Filter Vessel Rehabilitation Project•RO Membrane Replacement Project•Water Treatment Plant Improvements Project • Next Steps Funding opportunities•Develop implementation schedule and program•term goals for treatment plant-Define interim, short and long•effective approach for PFAS treatment-Determine cost•Evaluate shifting capacity to the RO system•Evaluate PFAS treatment alternatives••Evaluate raw water sources•Water Treatment Master Plan• Thank you for your time Questions? Raw Water Supply Susceptible to contamination•Lower yield•High hardness•High organics•Fresh water•Shallow wells•Surficial Aquifer Wellfield•Surficial Aquifer– Raw Water Supply Alternative Water Supply •contaminationNot susceptible to •Artesian pressure•Higher capacity•Higher in salts•confined aquifer–Deeper wells •Brackish water••Floridan Aquifer– 0.0 MDF/ADFCapacityPlantTotalHistoricalProjection SAS ADF Demand ProjectionPermitted Annual FAS AllocationPermitted Annual SAS Allocation2018 LEC-WSP MDF Projection2018 LEC-WSP ADF ProjectionFilter Plant CapacityRO Plant CapacityTotal Plant CapacityHistorial ADFHistorical MDF Past Total Water Production & Projected Buildout Water Demand for VOT End of YearFLOW (MGD)2040203920382037203620352034 20332032203120302029202820272026202520242023202220217.06.05.04.03.02.01.0 Ion Resin replacement costsHazardous materialResin disposal costsDisadvantages Doesn’t require secondary treatment•Effective in waters with higher TOC•Smaller footprint when compared to GAC•Requires low operating pressures •Specific/ partial removal of contaminantsAdvantages resinsuch as PFAS by binding to the removes negatively charged ions, Selective anion exchange •Summary Exchange Granular Activated Carbon (GAC)Higher EBCTRequires larger footprint than IEX to treat same flow Hazardous substanceHave to dispose of mediaDoesn’t remove short chain compoundsPFAS breakthrough sooner in waters with higher TOCDisadvantages Doesn’t change water chemistryand odor compounds)Can remove secondary contaminants (TOC, color, taste FlexibleSimple processTypically lower capital costLower operating pressures compared to membranesAdvantages carbon mediaAdsorption of organic material onto activated •Summary Nanofiltration stabilizationRequires secondary treatment for Disposal of concentrated waste streamHigher Operating Cost (Energy)Higher Capital CostDisadvantages constituentsRemoves other unfavorable water quality Superior water qualityExcellent PFAS removalAdvantages Pressurized process•permeable membrane-through semiRemoval of dissolved constituents •Summary