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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

12

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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)

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Bill Stein LBG-Guyton Associates bstein@lbg-guyton.com

(210) 590-1331