1. DEEP GROUNDWATER DRILLING
CENTRAL TEXAS BY
WILLIAM FEATHERGAIL WILSON, PG #21
STRATA GEOLOGICAL SERVICES
GSA

2. TEXAS HILL COUNTRY

3. Regional Cross-Section

4. KERR COUNTY

5. RESEARCH WELLS (12) 8 4 9 6 5 7 11 3 2
This slide depicts all of the Headwaters monitor and research wells that have been drilled over the past few years.
Additional drilling is scheduled for 2008. 1

6. RESEARCH WELLS (12) Drilled through the entire Cretaceous System
Depths ranges: 610’-1330’ (~ 11,000’)
Lithologic logs – stereo 10’ intervals
Geophysical logs
Drilled 12 wells – 8 years – HGCD Conservation district

7. RESEARCH WELL RESULTS MAPS CROSS-SECTIONS ANALYTICAL MODELING
ISOPACH
FACIES
ISOTOPE AGES
FLOW DIRECTIONS
RECHARGE CONCEPTS
CROSS-SECTIONS
ANALYTICAL MODELING
AQUIFER AGE DATES – ISOTOPES
PUMP TESTS
DEMAND –SUPPLY PREDICTIONS

8. Cretaceous Stratigraphy
Fm/Group
Members
Trinity
Period
Age 99
Edwards
Albian
Upper
Lower
Upper
Glen Rose
112
Hensel
Bexar
Cow Creek
Hammett
Cretaceous
Middle
Pearsall
Aptian
This is a depiction of the aquifers and aquitards present within the county.
The blue designates the major and minor aquifers.
The great preponderance of groundwater in the county is derived from the Hensel and Cow Creek units.
Often the Hensel and Cow Creek are interconnected into one aquifer.
The two major aquitards are the Upper Glen Rose and the Hammett clays.
121
Sligo
Neocomian
Lower
Hosston
144
Strata Geological Services, Inc

9. Kerr Co Geology

10. HENSEL FACIES TIME SLICE

11. HENSEL FLOW DIRECTIONS

12. CROSS-SECTION -SE-NNE

13. CROSS-SECTION – S-N

14. CROSS-SECTION – W-E

15. CROSS-SECTION 5-12

16. EDWARDS FLOW DIRECTIONS

17. C-14 Aquifer Age Dates (uncorrected)
,000 years
<10,000
>20,000

18. % Modern Carbon
High
Low

19. RECHARGE & ISOPACH MAP
This interesting map depicts a combination of Hensel thickness data across a large area of the Texas Hill Country. It introduces some of the recharge issues that move groundwater into all of the confined units in the county.
Note the stippled yellow areas depicting the Hensel Sand outcrop and the recharge arrows. Rainfall recharges the Hensel outcrop and moves SE beneath the Upper Glen Rose aquitard into Kerr County. Another component of groundwater is derived from the Hensel sands that lie below the Edwards Plateau in the unconfined portion of the Edwards-Trinity aquifer.
One implication is that dewatering of the Hensel sands in Kimble and Gillespie Counties will occur before they reach Kerr County over the next 50-years.

20. GROUNDWATER STORAGE The Hammett clay wedge separates the Hensel South
from the Hensel North via
facies change
11,986 ac ft
recoverable
sans annual
recharge
15,981 ac ft
using 20%
recovery
This computer generated map depicts the thickness of the Hensel Sands both north and south of the Hammett clay limit. The equation depicts and estimate of the water in storage at any one given moment in time. The factors that go into the equation can be changed either increasing or decreasing the water in storage. This equation represents mean value parameters.
Note the thick areas in various shades of brown and the thin areas in shades of green.
Mean aquifer thickness

21. PALEOZOIC SUBCROP

22. Structural Elements

23. SUMMARY
REPRESENTS A SNAPSHOT OF DEEP GROUNDWATER DRILLING IN CENTRAL TEXAS
ADDITIONAL PRIVATE AND PUBLIC DEEP DRILLING HAS BEEN CARRIED OUT ACROSS THE TEXAS HILL COUNTRY UTILIZING THE SAME TECHNIQUES
RESEARCH CONTINUES IN COOPERATION WITH WATER DISTRICTS, DEVELOPERS, AND PUBLIC WATER SYSTEMS

24. SUMMARY
KERR COUNTY DETAILED REPORT (BOOK) BEING PREPARED (~120 PAGES), MAPS, CROSS-SECTIONS, ETC.
RESEARCH WILL BE EXPANDED TO INCORPORATE DEEP GROUNDWATER DRILLING DATA AND INTERPRETATION ACROSS ADJACENT COUNTIES

25. CONTACT INFORMATION
WILLIAM FEATHERGAIL WILSON, PG #21
Strata Geological Services
13505 FM 462
Bandera (Tarpley), Texas 78003
Office –
Thank You!