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 n 20% fresh <1,000 ppm TDS n 50% brackish water 1,000 - 3,000 TDS n 25% brackish water 3,000 - 10,000 TDS n 5% saline water >10,000 ppm TDS –(source: NM Bureau of Mines & Mineral Resources, 1965, Mineral and Water Resources of New Mexico: Bulletin 87)

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

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

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

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

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

9. LIVINGSTON ASSOCIATES, P.C. Consulting Engineers Example RO Performance Feed n TDS = 2,250 mg/L n Cl = 189 mg/L n SO 4 = 1,220 mg/L n Ca = 353 mg/L n Hard = 1404 mg/L n pH = 7.3 Product n 25 mg/L n 5 mg/L n 3 mg/L n 12 mg/L n 6.0

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

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

12. LIVINGSTON ASSOCIATES, P.C. Consulting Engineers MEMBRANE SCALING n Scale formation on membrane surface n Sparingly soluble salts (CaSO 4, BaSO 4 ) n Will cause “tail-end” membrane scaling n Increased operating pressure and decrease in salt rejection

13. LIVINGSTON ASSOCIATES, P.C. Consulting Engineers BWRO Problem Salts n CaSO 4 n BaSO 4 n SrSO 4 n CaCO 3 n CaF n Fe n Mn n Al n SiO 2

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

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

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17. O&M Cost n Power10% to >50% n Labor80% to <15% n Membranes<15% to 25% n Chemicals 25% n Concentrate disposal n Higher TDS, greater O&M

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

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

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

21. LIVINGSTON ASSOCIATES, P.C. Consulting Engineers Ft. Stockton, Texas n 6 MGD RO Plant (3 MGD blend) n TDS1600800mg/L n Sulfates430215mg/L n Hardness600300mg/L n Recovery80%,brine to WWTP n Cost= $0.30/kGal (blended)

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

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

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

25. LIVINGSTON ASSOCIATES, P.C. Consulting Engineers Gallup (White Cliffs) n 15,000 GPD RO Plant n TDS*3,000150mg/L n Recovery85%,brine to WWTP n Capital Cost= $50,000 n * - varies

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