why desalination in el paso? - university of arizona
TRANSCRIPT
Why Desalination in El Paso?
John Balliew, P.E.Vice President
El Paso Water Utilities
Solution = Desalination Plant
??Issues
Technology
Water Resources and Drought
Unique Site Specific Conditions
Comfort Level
Cost of Supply
Technology
• Ongoing improvement in membranes• Substantial improvement in anti-scalants
especially to address silica• EPWU conducts long term pilot testing of
membranes and concentrate disposal technologies
Water Resources and Drought
• From 1967 through 1987 EPWU had excess production capacity and was drought proof
• By drought proof we mean in the event no surface water was available, sufficient groundwater was available to meet demand
• Between 1987 and 1997 EPWU lost 46 MGD of groundwater capacity due to brackish water intrusion
Decline due to brackish water
intrusion
Water Capacity
Brackish Groundwater Intrusion
1997-2002 OperationYellow = In service
Red = Out of Service
Airport Area
Lower Valley
Emergency Drought Supply
• After 10 years of drought in the Rio Grande Basin, projections for 2004 showed an 8MGD deficit in supply
• Due to distribution system constraints, the deficit would be focused in the Lower Valley
• An accelerated program for wellhead desalination was implemented in 2002 and 8MGD placed in service for 20042004
1997-2002 OperationYellow = In service
Red = Out of Service
Lower Valley
Lower Valley Wellhead Desalination
• 11 Wells• Skid-mounted RO unit at each well• Treat high salinity and high arsenic
Typical RO Unit
Need for Long Term Supply
• Fort Bliss forecasts 7.5 MGD of additional demand needed for base expansion– Desalination is the assumed solution
• To be near drought proof, EPWU needs 20 MGD additional water– Desalination is the assumed solution
• These needs were best suited to one treatment plant
Joint Desalination Facility (JDF)
• EPWU and Fort Bliss• Currently in production• Desalination Plant and some wells located on
Fort Bliss• Concentrate disposal by injection well
1997-2002 OperationYellow = In service
Red = Out of Service
Airport Area
Existing Airport wells (15)– 18.5 mgd
Blend wells (16)–New wells on Ft Bliss that blend with permeate–12 mgd
Desalination Concepts
• Existing wells 18.5 mgd• Blend wells 12.0 mgd• Total supply 30.5 mgd
• Concentrate (Disposal) 3.0 mgd• Project yield 27.5 mgd
• Ongoing work by Fort Bliss identified a potential formation suitable for deep well injection
• Following decision to collaborate, extensive testing confirmed injection as the least cost solution for concentrate
Unique Site-specific Conditions
Concentrate DisposalInjection Well
• Fort Bliss contracted for four test holes• EPWU contracted for pilot well• Application was made to TCEQ and approved• Three wells were constructed• Operation very successful thusfar
Injection Well Basics
• Approximately 4000 feet deep• Formation contains water about 8,300 mg/L
TDS at 160 degrees F• Very permeable• Defined and contained
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GW SW Recl LV Desal JDF Import
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Cost of EPWU Water
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GW SW Recl LV Desal JDF Import
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Cost of EPWU Water
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GW SW Recl LV Desal JDF Import
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Cost of EPWU Water
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GW SW Recl LV Desal JDF Import
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Cost of EPWU Water
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GW SW Recl LV Desal JDF Import
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Cost of EPWU Water
164 228433 419 500
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GW SW Recl LV Desal JDF Import
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Cost of EPWU Water
Conclusions
• EPWU has addressed drought and salinity impacts to Lower Valley wells with wellhead RO units
• EPWU has moved from least expensive water supply to sources that are more expensive
Conclusions Continued
JDF represents opportunity:– Intercept brackish groundwater– Better utilization of local resources– Protect fresh groundwater areas for drought– Size of project translates to reduced costs
Questions?
John Balliew, P.E.Vice President
El Paso Water Utilities