I I OF-WTWI-1985-34 I I CHARACTERIZATION S UDY OF THE OGALLALA AQ .IFER, I NORTHWEST TEXA I by Ronit Nativ and D. 'Anderso Smith I I I Prepared for the U.S. Department of Ene' gy I Office of Nuclear Waste Is lation under Contract No. DE-AC97- 3WM46651 I, I I Bureau of Economic Geo ogy W. L. Fisher, Directo The university, of Texas at rustin" I University Station, Bo X Austin, Texas 78713 I I 1985 I DRAFT! I ~ ---,,:! I I I CONTENTS I INTRODUCTION 1 DESCRIPTION OF STUDY AREA 1 I Location • 1 Physiography. 3 I Climate • 3 Soils • 5 I i GENERAL HYDROGEOLOGY OF THE OGALLALA AQ IFER • 5 I CRITICAL ISSUES • 7 DATA ACQUISITION . 8 GEOLOGY RELATED TO HYDROLOGY 10 Quaternary strata 10 The Tertiary Ogallala Formation • 12 Cretaceous strata 15 Triassic strata 16 Permian strata • 20 HYDROLOGY • 24 Distribution of porosity and hydraulic conductivit • 24 I Recharge. 29 Discharge. 34 Potentiometric surface and saturated thickness of the Ogallala aquifer • 36 48 GEOCHEMISTRY • . ' Chemical and isotopic composition of Ogallala w ter • 48 Lithologic and structural effects on Ogallala wat r chemistry. 61 Effects of water-level altitudes on Ogallala wat r chemistry • 61 iii LORAFTl -----------._- : • Effects of natural recharge from precipitation on Ogallala water chemistry 65 • Effects of underlying aquifers on Ogallala water emistry 68 The Cretaceous aquifer. 69 - The Triassic aquifer. 72 The Permian aquifer. 76 • Effects of oil field brine contamination on 0 water chemistry. 80 FLOW MODEL OF THE OGALLALA AQUIFER. 83 PRELIMINARY OBSERVATIONS RELATED TO A ,",uuu..J'uE NUCLEAR WASTE REPOSITORY AND THE OGALLALA AQUIFER 85 ACKNOWLEDGMENTS 89 REFERENCES • 91 APPENDICES 1. Mean values for chemical parameters of water • 99 2. Analytical data for water samples. 100 3. Tritium in ground water. 102 4. Mean values for chemical parameters of brines 103 Figures 1. Study area and location of wells 2 2. Mean annual precipitation • 4 3. Generalized soil map 6 4. Geologic units underlying the Ogallala Formation .. 11 5. Isopach map of the Ogallala Formation 13 6. Percentage sand and gravel map of the Ogallala 14 7. Hydraulic characterization of the Cretaceous-Ogall 17 8a. Hydraulic characterization of the Permian-Triassic 18 8b. Hydraulic characterization of the Triassic-Permian' act 19 iv I 9a. Hydraulic characterization of the Triassic-Creta eous contact 21 - 9b. Hydraulic characterization of the Cretaceous-Tri ssic contact 22 I - 10. Hydraulic characterization of the Triassic-Ogallaa contact 23 I 11. Hydraulic characterization of the Permian-Ogall ila contact • 25 12. Specifi,c yield map of the Ogallala aquifer 26 I 13. Permeability of the Ogallala aquifer • 28 14. Isotopic composition of water in the High Plains 32 I 15. Present-day flowing springs in the Panhandle 35 I 16. Annual pumpage and recharge in the Ogallala aqu fer . 37 17. Approximate altitude of water level in the Ogall , a aquifer 38 18. Potentiometric surface in the Ogallala aquifer ve sus topography. 40 I I 19. Changes of potentiometric surface in the Ogallal· aquifer. 41 I 20. Water levels in the Cretaceous and Permian aqui !ers 42 21. Water-level head difference map between the 0 llala I and Cretaceous aquifers, and the Permian aquife 43 22. Water-level head difference map between the 0 llala and Triassic aquifers 44 23. Approximate saturated thickness of the Ogallala 46 24. Percent of Ogallala area versus saturated thickn 'ss 47 25. Dissolved-solids content in Ogallala water 49 26. Chloride content in Ogallala water 50 27. Chemical facies and isotopic composition of Oga lala water 52 28. Distribution map of IS 180 values in Ogallala wat r . 53 29. Distribution map of 3H values in Ogallala water: 54 30. Distribution map of 613 C values in Ogallala wat r . 55 31. Distribution map of 634S values in Ogallala wat r . 56 32. Piper diagrams of Ogallala water . 57 33 • Salinity curves of mean ions in Ogallala water 59 v DRAFT . ----.-._- • ----, . •! • 34. Bivariate plots of Ogallala water . 60 35. Water facies versus saturated thickness of the Ogal ala aquifer 62 • 36. Arsenic concentrations in the High Plains . 64 37. 0180 versus o2H in precipitation in the High Plains 66 • 38. Piper diagram of Cretaceous water 70 • 39. Bivariate plots of Cretaceous water 71 -. 40. Salinity diagrams of Ogallala and Cretaceous water. 73 41. Bivariate plots of the Triassic Dockum aquifer . 75 42. Salinity diagrams of Ogallala and Triassic water. 77 • 43. Bivariate plots of the Permian aquifer 79 • 44. Piper diagram of oil field brines 81 45. Bivariate plots of brines 82 • 46. Salinity diagrams of contaminated Ogallala water a d oil field brines 84 I 47. Salinity diagrams of contaminated Ogallala water a d saline lake water. 86 • 48. Salinity cross section of the Ogallala and underlyin aquifers • 87 I • ,----_._---------- --_ .. _... _--- vi I INTRODUCTION I The Ogallala aquifer, which is the main water s pply in the High Plains of Texas, is I being severely depleted by extensive pumpage for rrigation. The aquifer overlies the Permian evaporites that are being considered as a po ential repository for the disposal of I high-level nuclear wastes. Potential contamination .of the aquifer by these wastes and I further depletion of the limited water resources are major concerns of the people in the area. I The purpose of this work is to develop a gener I hydrogeologic characterization of I the aquifer that will serve as a firm basis for accu' ate evaluation of aquifer recharge I mechanisms relevant to problems stemming from acc·~ental spills of radionuclides at land surface and possible interactions of the radionuclides . ith deeper hydrologic units. Aquifer • hydraulics r~levent to problems that may be encounter d in shaft construction were studied as well. i The existing geologic, hydrologic, geochemical, . nd isotopic data are integrated into • ! • a regional hydrogeologic model for water and olutes. The model enables (1) an understanding of recharge/discharge relationships,: ages of water, and rock-water • interactions, and (2) the tracing of cross-formational I flow between the Ogallala and the underlying aquifers. • This report presents preliminary conclusions of r search conducted from August 1984 • through August 1985. : • DESCRIPTION OF STUDyl AREA • Location • The Ogallala aquifer is situated in the High PIa ns of northwest Texas (fig. 1). The High Plains of Texas are part of the southern exte sion of the Great Plains of North • America. The aquifer extends westward through ew Mexico and northward through • 1 • H·~rtloy ~oore Hutchinson R'oberts Hemphill ~ 066 ~b ,-:-:.,,- .. (5.. .. -- \I, ~ ~~ V2Ng.J EX PLANAT ION OLoham <'JALi'~r' p~tter (""I Carson Gray I/heeler f.-..j' J -~ ~,.~.!; . 063 ~ 62 :.'~ 46 . ~~9 @ ~oJ~ A well that was sampled ?-t~1'"@5, 'J~ . , for this study (app. 3) '1'4~, 60 . ~. O JUf Smith ijanda J1 57 Armstrong Collingsworth 081 ~~:v '/ olSi} Ralls A well that was sampled ~ by R. Basset (1980, ). i~~~ . 0 53 58 ~ unpublished data) Or.;; '54 ~@ ~ I Parmer Cas tro Swisher 82lsco~ Hall Childress , 5 . 5~1 ./ 0 Ogallala ·079 . " ~. ..\/. @ Cretaceous 8anoY71 • lamb Hal e Motley . Cottle 01-8 FIO~~ Permian 0 0 7 7 .r -South Plains Plain.le am 0., ~ Triassic 72 O~~,.. @ 0 ~ ~)5 P.t, rsburn @78·. -v 7' 9-11,12 4·~>o.;"l· Oga 11 ala + Cretaceous Cochran Crosby . (g Dick.ens . Ki ng ® Hockley ~6LUbbOCk '. 043 O· 0 McAdoo ® Ogallala + Triassic 25-29 ~~V-v.- I ® 15 45~ o 0 '" .~ ., i ~ Ogallala on Cretaceous Contact . Yoakum Terry lynn 69 0 Kent Stonewall (] ® ·Oga 11 al a on Permi an Contact ' 42 J 40 e 9 :i 0 ~ , @Ogalla1a on Tri'assic Gaines. Dawson ~Borden' Scurry FI sher Contact 37 O~ . i:; ~ i'1 : ., Andrews 6\g4 Mart In "~ ~ Mitchell Nolan ~ ... ,. 31 35 0 ~n n~ ,;f 811 .. c..--J ~Ector -Hldl.o1nd Glasscock Sterll n9 Coke (.r"'_<~. ,-..v,,~ .... ~"CI - \ _,.I",t"" ~-' ""r"e ,A ,..v ""'2", Figure 1. Study area and location of wells samplE d in the High Plains. 2 - Oklahoma, Colorado, Kansas, Wyoming, Nebraska, and outh Dakota. However, this study - is limited to the area of Texas south of the Canadian iver. The southern boundary of the ~ aquifer is the southern extension of the Ogallala . ormation in Ector, Midland, and Glasscock Counties and the eastern boundary is the R ~ling Plains. The western boundary - of the section of the aquifer discussed in this study is a bitrarily placed at the Texas - New II Mexico border, and therefore functions as an open hyd' ologic boundary. In future reports the western boundary will be extended to the wester· escarpment of the High Plains in New Mexico. The amount of hydrologic an~ chemical ata from New Mexico is relatively - small compared to that from Texas, so no major chan es in the conclusions presented in II this study are anticipated. II Physiography II The High Plains of Texas form a well-defined, t pographlcally isolated plateau that dips toward the southeast into the Rolling Plains. L rge parts of the High Plains have II scattered depressions called playa lakes. These de pres ions range from a few feet to 50 ft I II (1 to 15 m) or more in depth, and from a few hundred eet to a mile or more in diameter. Runoff following large rains accumulates in these d pressions and forms ponds. As a i II result, large areas of the High Plains have poorly dev loped drainage systems and all the II streams that head on the Rolling Plains are intermitten or have very small perennial flow. Climate II The High Plains of Texas have a semiarid climate Annual mean precipitation, based on 30 years of records (Bomar, 1983), ranges from 14 i ches across the southern Panhandle • to 20 inches in the northern Panhandle (360 and 510 m ,respectively).