DIKEWATER RELATIONSHIPS TO POTENTIAL GEOTHERMAL RESOURCES ON LEEWARD WEST MAUl, STATE OF HAWAII A THESIS SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAII IN PARTIAL FULFILLMENT OF THE REQUIRMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN GEOLOGY AND GEOPHYSICS MAY 1985 By Kevin Kennedy Thesis Committee: Doak C. Cox, Chairman Donald M. Thomas L. Stephen Lau ACKNOWLEDGEMENTS First and foremost I would like to thank Dr. Donald Thomas. His initial support, both financial and spiritual, and his continued support throughout this project are most gratefully acknowledged. I would like to thank Dr. Thomas further for introducing me to the numerous techniques and art of chemical modeling and his continuing guideance and willingness to help. Secondly I would like to thank Dr. Doak Cox for his thourgh reviews and editorial comments. Dr. Coxs observations and comments forced a lazy student into quality and validity conciousness. I would also like to thank Dr. L. Stephen Lau for his guidance in the tritium study and aiding in the financial support, not to mention his contribution to the majority of my education in Groundwater Hydrology. I can not thank the people of Pioneer Mill, Co. in Lahaina enough. All field work was conducted on Pioneer ~1i 11 property and they could not have been more generous and helpful. A specialmahalo to Don Ge-rbig, Field Supervisor. A special thanks to Dave Mills for doing the ion chemistry analyses and his field assistance. iii TABLE OF CONTENTS ACKNOWLEDGEMENTS ••••.•••••••••••••••.••.•.•.••.• iii LIST OF TABLES e •••· •••••••••• e •••••••• e ••••••• e.. vi LISTS OF FIGURES •••.•••.••.•••.•••••••.•••••..•. viii I~ ~ ~ ~ CHAPTER INTRODUCTION e e e e e e e 0 e e e e 0 e e 0 e 0 e e e 1 CHAPTER II. GEOLOGY, CLIMATE, AND HYDROLOGY Geological Setting •.•••..•••.•••••. 3 Climate ••••••••.•.••••••••••..•..•• 16 Hawaiian Groundwater Hydrology..... 17 Geothermal Resource Potential...... 25 CHAPTER III. GEOCHEMISTRY AND TRITIUM CHEMISTRY · 28 Introduction to Geochemical Study . 28 Introduction to Tritium Study..... 42 CHAPTER IV. SAMPLING, METHODS, AND RESULTS Sampling and Sample Description 56 Methods ••••••.•••••••••••••••.•.••• 61 Res u1 t s •.•.•••.••••.••........••.•. 61 CHAPTER V. GEOCHEMICAL, TRITIUM, AND PREVIOUS WORK RESULTS AND DISCUSSION Geochemical Results and Discussion.. 65 Points of Discussion Based on Ion Chemistry Data, Non-Thermal Water ••• 66 Points of Discussion Based on Ion Chemistry Data, Thermal Water e •• e.e. 71 Points of. Discussion from Tritium Data ••.•••.....•.....•.•......••.... 105 Points .. of .Discussion..from ... P.revious Work ••.•••.•••.....•••.••.••••••.•.. 119 CHAPTER VI. SUMMARY ••••.••.••....•.•..•••..••••. 126 Geothermal Resource Potential....... 128 Water Resources ......•...•.•••••••.• 130 CHAPTER VII. CONCLUSIONS 132 iv CHAPTER VIII. RECOMENDATIONS FOR FUTURE WORK •..•• 134 APPENDIX ••••.••.•.••..•••.•.•••••••••••••••••••••• 136 BIBLIOGRAPHY ••.•• eo ••••••••••••••••••••••••••••••• v LIST OF TABLES Table Page 1 Sampling locations and sampling months for dike spring, stream, Maui-well, and rainwater samples, Maui and Oahu •••••• 58 2 West Maui chemistry sampled in January 1983 ~ ~ ~ ~ ~ ••••••••••••••••••••••••••••• 62 3 West Maui chemistry sampled in July 1983 •••••••••••••••••••••••••••••••••• 63 4 West Maui tritium chemisstry 64 5 Temperature and chemistry of Q1Ke­ spring water samples 0-1, 0-2, and 0-6 67 6 Chloride concentration and flow rates for spring samples 0-1, 0-2, 0-3, and 0-6 ••••••••••.•••.•••••••••••••••••••••• 69 7 Water chemistry from two warm-water samples, 0-3 and P-pump ............... 72 8 Calculated background groundwater chemistry ••••••••••••••••••••••••••••• 75 9 P-Pump chemistry and calculated chemistry, January .................... 78 10 P-Pump chemistry and calculated chemistry, July ••••••••••••••••••••••• 79 11 Chemistry of 0-3 and P-Pump ••••••••••• 80 12 Calcium and sulfate concentrations and temperature measurements, 0-3, P-Pump • 83 13 Average calcium and sulfate concentra­ tion and temperature, 0-3 and P-Pump •• 84 14 Average calcium and sulfate concentra­ tion and temperature, 0-1, 0-2, 0-6 ••• 87 15 0-3 hot water components, January ••••• 94 .vi LIST OF TABLES (cont.) Table Page 16 P-Pump hot water components, January •• 9.5 17 0-3 hot water components, July •••••••• 96 18 P-Pump hot water components, July ••••• 97 19 P-Pump hot water components, January minus seawater 9.8 20 P-Pump hot water components, July minus seawater •••••••••••••••••••••••• 99 21 Calcium and sulfate concentrations •••• 101 , (\'.1 Chloride to magnesium ratios ••••••••.• ..LV-J 23 Tritium levels, Maui and Oahu ••••••••• 107 24 Rainwater tritium, Oahu ••••• ~ ••••••••• 109 25 Tritium activities for basal wells and high-head, thermal water •••••••••••••• 111 26 Tritium activities for N- and P-Pump •• 117 27 Tritium from tunnel water 118 vii LIST OF FIGURES Figure Page 1 Map of Hawaiian Archipelago ••••••••••••••• 4 2 Map of the eight major Hawaiian islands ••• 6 3 Map of Maui showing the Lahaina District 9 4 Geologic map and index of the island of Maui •••••••••••••••••••••••••••••••••••••• 10, 11 5 Detatiled geologic map of the Olowalu- Ukumehame area ••••••••••••.••••••••••••••• 12 6 Topography and rift systems of Maui ••••••• 15 7 Mean annual rainfall, Lahaina District, Maui ............ .......................... 18 8 Ghyben-Herzberg relationship •••••••••••••• 20 9 Hydrologic types in Hawaii •••••••••••••••• 23 10 Plot of tritium in Hawaiian rain vs. time. 48 11 Tritium content of precipitatiion at Vienna and Stuttgart •••••.•••••••••••••••••••••• ~ 49 12 Sampling locations •••••••••••••••••••••••• 60 13 Calcium sulfate solubility Ksp VS. temp ••.• 89 14 Depiction of Tritium phase lag 113 15 Salinity and temperature profile of P-Pump. 120 CHAPTER 1 INTRODUCTION The West Maui Volcano has not been active in historic times. Thus, the discovery of thermal waters in the 19308, a product of v6lcanic activity, was not anticipated iR West Maui wells. However, distinctly warm waters were found on the leeward side of West Maui in three ground~.ater 'developments: (1) drilled wells a't D the Pioneer Mill in Lahaina (30 e); (2) a Maui-type well in Ukumehame (35°C); and (3) a high-level horizontal water . 0 d evelopmen t tunn e 1 ··.i n 0 Iowa1 u (24 C) • West Maui volcano differs from most Hawaiian volcanoes by having steeper dips, more large intrussive bodies, thicker dikes with a more radial distrib~tiont and a more nearly circular form. The massive dike complex and radial dike form provide abundant water storage in the West Ma·ui Mountains. The vast am'ount' of water in the dike swarms is due to the high rainfall in the mountains, the exceptionally high permeability of the intervening Wailuku flows t low permeability of -the dikes and t eir .. radial diverg.ence from the area of high recharge t which disperses water in all directions, and enough dike intersections to create semi-isolated dike compartments with high heads and considerable storage. 1 The investigation, where results are reported here, relates to the ~arm groundwaters of the Olowalu-Ukumehame are of West Maui (designated Sub~Area C, Lahaina District, by the U. S. Geological Survey). It was undertaken to determine, so far as possible, the relationship of the occurence .of these warm waters to the geologic structure and groundwater hydrology of the area, the source of theii heat, and the potential for development of energy from them. In this investigation spring and well waters were sampled and analyzed for the major ions and for the tritium isotope. These methods, combined with standard hydrologic met~~ds, provide the data on which this study is based. 2 CHAPTER II GEOLOGY, CLIMATE, AND HYDROLOGY Geologic~l' Setting The West Maui Volcano, one of two volcanoes making up the island of Maui, is part of the Hawaiian-Emperor chain of islands and seamounts that stretches more than 6000 km across the middle of the northern Pacific Ocean. This chain of islands was formed primarily by the eruption of tholeitic basalts. Small amounts of other volcanics along with sediments from erosion and the formation of coral have added to the bulk of the Islands. The volcanic eruptions and resulting island masses were, and still are in the case of Hawaii Island, the result of a "hot spot" or "mantle plume" beneath the middle of the Pacific Plate. A current belief is that the northwestern migration of this plate over the "hot spot" during the past 25 million years has resulted in the northwest­ southeast lineation of these islands and seamounts that increase in age from the historically active volcanoes ot Haleakala (East Maui) and Kilauea, Mauna Loa, and Hualalei (Hawaii Island) at the southeast end of the chain; to the long dormant Midway Island at the northwestern end (see Figure 1). 3 KURE.I. .MIOWAY I. ,04 C 1 PEARL ANO HERMES REEF '"'I C -I C L1SIANSKI I. o e C eLAYSAN I. -4 I\t G::AR=07:'N::ER:'""':'I-. .,-------__1--------1-25­ _FRENCH fRIGATE SHOAL t.: • NECKER I. • NIHOA I. NIIHAU I ()KAUAI KAULA I: 0AI1U~ MOLaKAI LANAIO~MAUI-=­ _ ~---t----_---+_...;.::KA;,:;H.:.:OO:.::L:.:A.::.W.:E-·-JI~o:I-­ ___ ~O HAWAII' ~ I> i.f=.3.0=0::::&i...600 Kilometers Figure 1. Map of Hawaiian Archipelago. Small inset shows the locations of the islands i.n the Pacific Ocean. The eight major Hawaiian islands lie within the southeastern 600,000 m of the chain (Figure 2). Each island consists of one or more shield-type volcanoes. One of these volcanoes (Mauna Kea) reaches as high as 4,556 m above sea level. These are some of the largest mountains on earth, rising more than 9,000 meters above the seafloor in the case of Mauna Kea and Mauna Loa. These volcanic mountains were formed, and are still being formed in the case of Haleakala, Hualalai, Mauna Loa, and Kilauea, by the eruption of tens of thousands of lava flows within central calderas and from rifts concentrated generally in two or three rift zones that radiate trom the calderas. The calderas, more or less circular in plan (Macdonald and Abbott, 1970), range from 3,000 to 5,000 (Kil~uea and Mauna Loa) up to 24,000 m in diameter (Kauai).