bill stein
TRANSCRIPT
AMTA/AWWA© 1
Bill Stein, PG LBG-Guyton Associates
San Antonio
San Antonio Water System BRACKISH GROUNDWATER DESALINATION PROJECT
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Presentation Outline • Brackish Water
– What ? – Why ?
• Feasibility Study / Test Wells
• Program Design • Production Wells • Treatment Plant • Injection Wells • Project Summary
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What is Brackish Water ?
Freshwater TDS* < 1,000 mg/L
Brackish Water TDS = 1,000 - 10,000 mg/L
Saline Water TDS > 10,000 mg/L
Seawater TDS ~ 35,000 mg/L
Brine TDS ~100,000 mg/L
* TDS = Total Dissolved Solids
USDW
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Why use Brackish Water ? Alternative Resource
• Texas 2002 Desalination Initiative
• Resource close to San Antonio to make it cost effective
• Un-tapped resource • Large volumes of
brackish water
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• Feasibility Study March 2006
• Test Wells Aug 2006 - May 2008
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General Geology
Wilcox Formation is deep and gets deeper toward the coast
Upper Wilcox aquitard isolates the freshwater Carrizo Aquifer from the brackish Wilcox
300 to 400 feet of producible Sand in the lower Wilcox
1,000 ft. 1,226 ft.
1,804 ft.
Land
1,784 ft.
Not to Scale
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Water Quality – Wilcox Formation
Sodium Sulfate/Chloride type chemistry
TDS = 1,300 – 1,500 mg/L
Sodium Absorption Ratio > 10
• Not Good for Irrigation
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Program Design
Phase 1 – 10 MGD permeate 12 MGD blended 12 or 13 Production
Wells 45 miles integration
pipeline Reverse Osmosis
Treatment Plant 2 or 3 Injection wells
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Production Wells Brackish Source
First 8 wells Constructed BGD-1 thru BGD-4 (Oct 2012) BGD-5 thru BGD-8 (Apr 2013)
Production Rate = 800 – 1,000 gpm TDS = 1,300 to 1,500 mg/L
BGD-9 thru -13 (designed 2013) Under CMAR (construct 2014)
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SAWS Water Strategy
SAWS Averaged 183 MGD
in 2012
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Planned Phasing Permeate Finished Water
Phase I 10 MGD 12 MGD
Phase II 20 MGD 24 MGD
Phase III 25 MGD 30 MGD
30 MGD Capacity at Buildout – Modular – 2 Parallel Systems (Process Trains)
of 15 MGD Each – Parallel Systems Carried Through
to Post Treatment – Interconnections for Reliability
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Reverse Osmosis
Skid Units
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RO Feed Pump #1
Permeate
Concentrate
Stage 1 Membrane Array
Stage 2 Membrane Array
M
SAWS BGD RO Configuration
Stage 3 Membrane Array
Booster Pump
M
Primary RO Unit #1
Concentrator RO Unit #1
RO Feed Pump #2
M
Stage 1 Membrane Array
Stage 2 Membrane Array
20 Vessels, 7 Elements
20 Vessels, 7 Elements
20 Vessels, 7 Elements
20 Vessels, 7 Elements
20 Vessels, 7 Elements
20 Vessels, 7 Elements
16 Vessels, 7 Elements
Primary RO Unit #2
Pretreatment
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RO Plant Location • Co-location with SAWS Twin Oaks ASR Facility
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Land Surface
Georgetown Edwards &
Upper Glen Rose Limestone
TD = 5,040 ft.
Midway Shale
Anacacho Limestone
Navarro Clay
Not to Scale
TD = 1,600 ft.
Production Well
Injection Well
Confining
Zone
~2,360 ft. Thick
Production Zone
~ 600 ft. Thick
Injection Zone
~ 860 ft. Thick
Wilcox Sand (Brackish Water)
Upper Wilcox Clay
Eagle Ford Shale, Buda Limestone, & Del Rio Clay
Austin Chalk
Carrizo Sand (Fresh Water)
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Classes of Injection Wells
I. hazardous wastes, industrial non-hazardous liquids, or municipal wastewater beneath the lowermost USDW
II. brines and other fluids associated with oil and gas production, and hydrocarbons for storage
III. fluids associated with solution mining of minerals beneath the lowermost USDW
IV. hazardous or radioactive wastes into or above USDWs. These wells are banned unless authorized under a federal or state ground water remediation project
V. inject non-hazardous fluids into or above USDWs and are typically shallow, on-site disposal systems
VI. Sequestration of CO2
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ADVANTAGE previous 13-month review period down to about 60 days
SAWS is first to get TCEQ General Permit for Class 1 injection well to dispose of the RO concentrate a minimum of 1/4-mile area of
review around each injection well
a local and regional hydrogeologic summary
well construction engineering injection volumes and rates mechanical integrity testing
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Class 1 Injection Test Well Concentrate Disposal
Multiple Casing Strings protects USDW
Injection Zone Edwards & upper Glen Rose Limestones
800 feet open hole completion
Total Depth: 5,000 – 5,300 feet
Native Edwards water salinity – 90,000 mg/L TDS
450 gpm Injection Rate
Two Class I Injection Wells for Phase I – about 1.1 MGD of about 15,000 mg/l concentrate
Well Nos. 2 & 3 (design 2013) Construct under CMAR (2014)
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Team and Timeline 2012 2013 2014 2015 2016
CMAR Selection
PM Selection
Pre - Construction Phase
Today
Conceptual Design Phase
Design Phase Program Management and Inspection
Construction Phase Commissioning Phase
Well Pkg . 1 B ( # 5 - 8 ) Construction
Work by Separate
Contractors
Well Pkg . 1 A ( # 1 - 4 ) Construction
Inj . Well # 1 Const .
2017
TEAM Project Manager - Black & Veatch Wells – LBG-Guyton Conveyance – URS Treatment – Tetra Tech Electrical / I&C – Gupta & Assoc.
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SAWS Program Summary
12-13 Production Wells with additional wells later (800–1,000 gpm each)
Raw Water Collection System
10 MGD Reverse Osmosis Treatment Plant
2-3 Class I Injection Wells with up to 5 permitted
1.1 MGD of concentrate at about 15,000 mg/L TDS Much less than Edwards Native
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SAWS Program Summary
SAWS Brackish Groundwater Desalination (BGD) Program located in southern Bexar County on SAWS ASR property –
Uses an un-tapped resource Takes advantage of State funding opportunities
Three Phase Program
– Phase 1 – 10 MGD (2016) – Phase 2 – 10 MGD (2021) – Phase 3 – 5-10 MGD (2026)