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Eddie C. Livingston, MSCE, P.E. Livingston Associates, P.C.

Considerations for Brackish Groundwater Use as a Water Supply for Small Water Systems and Municipalities. Eddie C. Livingston, MSCE, P.E. Livingston Associates, P.C. NM Brackish Groundwater Aquifer Assessment Workshop Albuquerque, NM January 15, 2004. Saline GW in NM.

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Eddie C. Livingston, MSCE, P.E. Livingston Associates, P.C.

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  1. Considerations for Brackish Groundwater Use as a Water Supply for Small Water Systems and Municipalities Eddie C. Livingston, MSCE, P.E. Livingston Associates, P.C. NM Brackish Groundwater Aquifer Assessment Workshop Albuquerque, NM January 15, 2004

  2. LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  3. Saline GW in NM • 20% fresh <1,000 ppm TDS • 50% brackish water 1,000 - 3,000 TDS • 25% brackish water 3,000 - 10,000 TDS • 5% saline water >10,000 ppm TDS • (source: NM Bureau of Mines & Mineral Resources, 1965, Mineral and Water Resources of New Mexico: Bulletin 87) LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  4. Establish Water Quality Goals • Meet USEPA/NMED primary and secondary drinking water standards • TDS <500 mg/L • Sulfate <250 mg/L • or will <1,000 mg/L TDS be acceptable? • Match current quality? • End user decision LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  5. Desalting Technologies • Reverse Osmosis (RO) - Pressure driven membrane ion separation process • Electrodialysis Reversal (EDR) - Low voltage electrical ion separation process • Ion Exchange (IX) - Replaces select ions for another (sodium for hardness) • various thermal (distillation) processes • New technologies LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  6. RO Membrane LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  7. Ion Rejection LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  8. RO Terms • Feed water (BW supply) • Permeate (product) treated water • Brine (concentrate) rejected salt stream • Recovery: percent of product water to feed water (ie; if feed = 100 gallons, and product = 75 gallons then recovery is 75%) LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  9. Feed TDS = 2,250 mg/L Cl = 189 mg/L SO4 = 1,220 mg/L Ca = 353 mg/L Hard = 1404 mg/L pH = 7.3 Product 25 mg/L 5 mg/L 5 mg/L 3 mg/L 12 mg/L 6.0 Example RO Performance LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  10. WELL BY-PASS FOR BLENDING PRE-FILTERS TO DISTRIBUTION RO PERMEATE RO ARRAY HIGH PRESSURE PUMP POST-TREATMENT CHEMICAL FEED (ACID, SCALE INHIBITOR) BRINE DISPOSAL WELL LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  11. Horizon City 6 MGD RO LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  12. MEMBRANE SCALING • Scale formation on membrane surface • Sparingly soluble salts (CaSO4, BaSO4) • Will cause “tail-end” membrane scaling • Increased operating pressure and decrease in salt rejection LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  13. CaSO4 BaSO4 SrSO4 CaCO3 CaF Fe Mn Al SiO2 BWRO Problem Salts LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  14. Concentrate Disposal • Concentrate 3X to 5X feed TDS • Concentrate flow 20% to 50% feed • Sewer system to WWTP • Deep well injection • Evaporation ponds, playas • Concentrated for zero-discharge • Beneficial uses, land application LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  15. RO Equipment • Pre-engineered “skid” mounted incl. pumps, pre-filters, chem feed, RO array and controls • For small systems from 15,000 gpd to around 500,000 gpd • Can be containerized or placed in a building • Modular for expansion LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  16. LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  17. O&M Cost • Power 10% to >50% • Labor 80% to <15% • Membranes <15% to 25% • Chemicals <10% to >25% • Concentrate disposal • Higher TDS, greater O&M LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  18. Desalination Cost Considerations • Target BW in lower TDS range (<5,000) • Maximize recovery, utilize scale inhibitor • Maximize blending potential, integrate • Evaporate or land apply concentrate • Use shallow wells near roads and power • Gravity flow delivery system, exist route • Use economies of scale, regional LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  19. BGW Quality Data Needed • TDS • Conductivity • pH • Temp • Major Cations/Anions • Fe/Mn/Al/Si LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  20. Possible Strategies • ID potential users, small and large • Evaluate opportunity for Regional supply where possible • Characterize BW resources within a practical radius, power and routes • Rank based on quality, yield, volume • Perform RO pilot study for costing LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  21. Ft. Stockton, Texas • 6 MGD RO Plant (3 MGD blend) • TDS 1600 800 mg/L • Sulfates 430 215 mg/L • Hardness 600 300 mg/L • Recovery 80%, brine to WWTP • Cost = $0.30/kGal (blended) LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  22. Ft. Stockton 6 MGD RO LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  23. WSMR Stallion Site EDR • 150,000 GPD • Feed TDS 3,600 ppm • Product TDS 500 ppm • Recovery 65% • Costs $2.00 per Kgal • Brine evaporated in pond LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  24. Alamogordo, NM • 6 MGD RO Plant; expand to 13 MGD. • TDS of GW 2,200 mg/L to 800 mg/L • Blend 60% RO to 40% GW • Recovery approx. 84%, brine to evap. • Capital Cost = $8 M (plant/pond) • Delivered Cost = $0.65/kGal LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  25. Gallup (White Cliffs) • 15,000 GPD RO Plant • TDS* 3,000 150 mg/L • Recovery 85%, brine to WWTP • Capital Cost = $50,000 • * - varies LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

  26. Questions? LIVINGSTON ASSOCIATES, P.C.Consulting Engineers

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