Construction, Geologic, and Hydrologic Data from Five Exploratory Wells on Rota, Commonwealth of the Northern Mariana Islands, 1999 Prepared in cooperation with the COMMONWEALTH UTILITIES CORPORATION, COMMONWEALTH OF THE NORTHERN MARIANA ISLANDS 145˚10' 145˚15' EX-1 DEPTH ELEVATION 0 602 Puntan Fina Atkos 90 500 130 P H I L I PP I N E S E A EX-2 EX-3 EX-4 400 Puntan EX-5 14˚10' Sailigai EX-1 300 Puntan Saguagahga 380 200 Puntan Haiña 100 Sasanhaya Bay Puntan sea level Taipingot 609 Puntan Poña 670 -100 P A C I F I C O C E A N 720 745 -143 14˚05'30” Open-File Report 2005-1042 U.S. Department of the Interior U.S. Geological Survey Construction, Geologic, and Hydrologic Data from Five Exploratory Wells on Rota, Commonwealth of the Northern Mariana Islands, 1999 By Robert L. Carruth Prepared in cooperation with the COMMONWEALTH UTILITIES CORPORATION, COMMONWEALTH OF THE NORTHERN MARIANA ISLANDS Open-File Report 2005-1042 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior Gale A. Norton, Secretary U.S. Geological Survey Charles G. Groat, Director U.S. Geological Survey, Reston, Virginia: 2005 For sale by U.S. Geological Survey, Information Services Box 25286, Denver Federal Center Denver, CO 80225 For more information about the USGS and its products: Telephone: 1-888-ASK-USGS World Wide Web: http://www.usgs.gov/ Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to repro- duce any copyrighted materials contained within this report. Suggested citation: Carruth, R.L., 2005, Construction, geologic, and hydrologic data from five exploratory wells on Rota, Commonwealth of the Northern Mariana Islands, 1999 : U.S. Geological Survey Open-File Report 2005-1042, 40 p. iii Contents Abstract. 1 Introduction . 1 Physical Setting . 4 Location and Name of Wells . 4 Acknowledgments. 6 Drilling Methods and History. 6 Geologic Logs. 18 Aquifer Tests . 18 Water Levels . 26 Water Quality . 32 Summary . 40 References Cited . 40 Appendices Provided in Excel Format Figures 1–3.Maps showing: 1. Loation and shaded relief of Rota, Commonwealth of the Northern Mariana Islands. 2 2. Location of the five exploratory wells drilled in 1999 and pre-existing wells in the northern plateau, Rota . 3 3. Generalized surficial geology of Rota. 5 4–8. Drawings showing: 4. Geologic log and construction details of well EX-1 (CUC well SP-MW1), Rota . 9 5. Geologic log and construction details of well EX-2 (CUC well SP-1), Rota. 11 6. Geologic log and construction details of well EX-3 (CUC well SP-2), Rota. 13 7. Geologic log and construction details of well EX-4 (CUC well SP-3), Rota. 15 8. Geologic log and construction details of well EX-5 (CUC well SP-MW2), Rota . 17 9–20. Graphs showing: 9. Drawdown and recovery with time during and after the 8-day sustained aquifer test (Aug 30 -- September 7, 1999), at well EX-2 (CUC well SP-1) Rota . 20 10. Drawdown with time during the step-drawdown aquifer test (September 8, 1999), at well EX-2 (CUC well SP-1) Rota. 21 11. Drawdown and recovery with time during and after the 8-day sustained aquifer test (October 27 – November 4, 1999), at well EX-3 (CUC well SP-2) Rota . 22 12. Drawdown with time during the step-drawdown aquifer test (November 4, 1999), at well EX-3 (CUC well SP-2) Rota. 23 13. Drawdown and recovery with time during and after the 8-day sustained-rate aquifer test (September 23 -- October 1, 1999), at well EX-4 (CUC well SP-3) Rota . 24 14. Drawdown with time during the step-drawdown aquifer test (October 2, 1999), at well EX-4 (CUC well SP-3) Rota. 25 15. Intermitent ground-water data at well EX-1 (CUC well SP-MW1), 2000-2001, Rota . 27 16. Intermitent ground-water data at well EX-2 (CUC well SP-1), 2000-2001, Rota. 28 17. Intermitent ground-water data at well EX-3 (CUC well SP-2), 2000-2001, Rota. 29 18. Intermitent ground-water data at well EX-4 (CUC well SP-3), 2000-2001, Rota. 30 19. Intermitent ground-water data at well EX-5 (CUC well SP-MW2), 2000-2001, Rota . 31 20. Specific conductance profile at well EX-1 (CUC well SP-MW1) , August 4, 2000, Rota . 33 iv Tables 1. Exploratory well name, CUC well name, location, and elevation of the five exploratory wells on Rota . 6 2. Construction summary of exploratory well EX-1 (SP-MW1), Rota . 8 3. Construction summary of exploratory well EX-2 (SP-1), Rota . 10 4. Construction summary of exploratory well EX-3 (SP-2), Rota . 12 5. Construction summary of exploratory well EX-4 (SP-3), Rota . 14 6. Construction summary of exploratory well EX-5 (SP-MW2), Rota . 16 7. Water-quality data at well EX-2 (CUC well SP-1) on June 6, 2000 and September 25, 2000, Rota . 34 8. Water-quality data at well EX-3 (CUC well SP-2) on June 6, 2000 and September 25, 2000, Rota . 35 9. Water-quality data at well EX-4 (CUC well SP-3) on June 6, 2000 and September 25, 2000, Rota . 36 10. Pesticides, herbicides, and other volatile organic constituents found to be less than detection limits in water samples from EX-2 (CUC well SP-1) on June 6, 2000 and September 25, 2000, Rota . 37 11. Pesticides, herbicides, and other volatile organic constituents found to be less than detection limits in water samples from EX-3 (CUC well SP-2) on June 6, 2000 and September 25, 2000, Rota . 38 12. Pesticides, herbicides, and other volatile organic constituents found to be less than detection limits in water samples from EX-4 (CUC well SP-3) on June 6, 2000 and September 25, 2000, Rota . 39 Appendices Provided in Excel Format 1. Lithologic descriptions of drill cuttings from Rota exploratory wells. 2. Data from 8-day sustained-rate aquifer test conducted on August 30--September 7, 1999, before installation of casing and gravel pack, well EX-2 (CUC well SP-1), Rota. 3. Data from recovery test, September 7, 1999, well EX-2 (CUC well SP-1), Rota. 4. Data from step-drawdown aquifer test, September 8, 1999, well EX-2 (CUC well SP-1), Rota. 5. Data from 8-day sustained-rate aquifer test conducted on October 27--November 4, 1999, before installation of casing and gravel pack, well EX-3 (CUC well SP-2), Rota. 6. Data from recovery test, November 4, 1999, well EX-3 (CUC well SP-2), Rota. 7. Data from step-drawdown aquifer test, November 4, 1999, well EX-3 (CUC well SP-2), Rota. 8. Data from 8-day sustained-rate aquifer test conducted on September 23--October 1, 1999, before installation of casing and gravel pack, well EX-4 (CUC well SP-3), Rota. 9. Data from recovery test, October 1, 1999, well EX-4 (CUC well SP-3), Rota. 10.Data from step-drawdown aquifer test, October 2, 1999, well EX-4 (CUC well SP-3), Rota. v Conversion Factors and Datum Multiply By To obtain Length inch (in.) 2.54 centimeter (cm) foot (ft) 0.3048 meter (m) mile (mi) 1.609 kilometers (km) Flow rate cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s) gallon per minute (gal/min) 0.06309 liter per second (L/s) million gallons per day (Mgal/d) 0.04381 cubic meter per second (m3/s) million gallons per day per square mile cubic meter per day per square kilo- [(Mgal/d)/mi2] 1,461 meter [(m3/d)/km2] Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows: °F = (1.8 x °C) + 32 Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows: °C = (°F - 32) / 1.8 Vertical coordinate information is referenced relative to mean sea level. Altitude, as used in this report, refers to distance above the vertical datum. Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at 25°C). Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) or micrograms per liter (µg/L). Construction, Geologic, and Hydrologic Data from Five Exploratory Wells on Rota, Commonwealth of the Northern Mariana Islands, 1999 By Robert L. Carruth Abstract Introduction Rota is the southernmost of the 14 small islands that make The island of Rota is about 45 mi north-northeast of Guam up the Commonwealth of the Northern Mariana Islands. in the western Pacific and lies between 14°06’ and 14°12’ north Reduced springflow at Matan Hanom and As Onan springs latitude and between 145°07’ and 145°17’ east longitude (fig. occurred during a drought associated with the 1997-98 El Niño. 1). The island is oriented on an east-west axial direction and is Water from the two developed springs constituted the only approximately 11.5 mi long and 3 mi wide. Including two small municipal water source for the island at that time. In April 1998, islets along the west shore, the land area of Rota is about 33 mi2 reduced water supplies forced the Commonwealth Utilities Cor- or about 15 percent of the land area of Guam.