James beach

Texas Alliance of Groundwater Districts

Texas Groundwater Summit

Brackish Groundwater Availability

James Beach, PGLBG-Guyton AssociatesAugust 27, 2015

OutlinePractical side of brackish developmentBrackish groundwater volumesManagement issues and brackish groundwater

production zonesThings to watch

~40,000 wellsDeep saline units not included

Texas BrackishGroundwater

West Texas

“ The complex nature of solution trough………..

The base of the formation is often difficult, if not impossible, to determine.”

“It is not uncommon to encounter a significant accumulation of clay in some wells. However, correlation of individual lithologic units over large distances is, at best, tenuous.”

-BRACs Pecos Valley Aquifer report

TWDB BRACs

Boring Location

BRACs Report: Base of Pecos Valley Alluvium

Base of Alluvium

Base of Alluvium

“The technique of using geophysical well log correlation was inherently biased toward a signature that indicated a coarse, unconsolidated geological unit overlying a more uniform siltstone or shale unit. This bias may have precluded us from including basal fine-grained deposits in the Pecos Valley Alluvium that are almost indistinguishable from the underlying Triassic and Permian units.”

-BRACs Pecos Valley Aquifer report

Characterization QuestionsOn a limited budget………….How many wells?How deep?Desired water quality for treatment?

Law of Diminishing Returns

Field InvestigationsTest DrillingWater Quality AssessmentAquifer Pumping Tests

Brackish ConsiderationsAreal extent and productivity of brackish

aquifer

Cost of treatment

Methods of concentrate management

Practical ConsiderationsBrackish groundwater should be

considered as an alternative new supply in some areas

Significant portion of brackish may not be in BGPZ

Feasibility and cost depend on many site-specific factors

Financial, regulatory, hydrogeologic and engineering issues should be considered simultaneously during all phases of the project

Take Home on Practical IssuesIn many places, brackish groundwater still requires

significant characterization

Typical groundwater development concepts still apply

Significant investment is generally required to develop a brackish project

Brackish Volumes

Estimated Brackish Volumes in Texas

2.7 Billion AF !!

2.7 Billion AF

Unconfined

Confined

Brackish Groundwater Availability

Region

Total Estimated Volume of Brackish Groundwater “In Place”

in all Aquifers (acre/feet)

Total Minimum Confined Volume of Brackish Groundwater

(acre/feet)

A- Panhandle 19,072,000 27,600 B- Region B 14,528,000 7,000 C- Region C 84,864,000 84,900 D- Northeast Texas 55,712,000 71,300 E- Far West Texas 125,004,800 377,600 F- Region F 371,548,800 1,299,500 G- Brazos 195,113,600 426,800 H- Region H 192,912,000 470,500 I- East Texas 195,432,000 437,400 J- Plateau 8,515,200 122,600 K- Lower Colorado 201,080,000 872,200 L- South Central Texas 416,576,000 1,191,200 M- Rio Grande 394,848,000 1,220,900 N- Coastal Bend 331,040,000 1,368,800 O- Llano Estacado 91,611,200 151,600 P- Lavaca 7,800,000 25,900 Total 2,705,657,600 8,155,800

Brackish Volumes in Texas

23

Balancing test

Highest Practicable

Level of Groundwater Production

Conservation, Preservation, Protection, Recharging,

and Prevention of Waste of

Groundwater, and Control of

Subsidence

Brackish Groundwater Production Zone Issues

Balancing desire to use brackish with long-term impacts

“significant” impact?extent of BGPZHow to implement production in BGPZWhat if BGPZ does have significant impact on

freshwater suppliesDetails of BGPZ in non-district areas

Pecos Valley MAGs

Looking Forward for BrackishMore Characterization NeededTrue value of water will be better identifiedLocal economies play important roleStrongly held viewpoints and beliefs (and water

still flows toward money)More Proactive Mitigation?Petitions and lawsuitsMore clarity with time….

LBG-GUYTON ASSOCIATESJames Beach, P.G.

[email protected] (512) 327-9640

Austin San Antonio Houston