|
|
|
QUALITY OF SHALLOW GROUND WATER IN RECENTLY DEVELOPED RESIDENTIAL AND COMMERCIAL AREAS, MEMPHIS VICINITY, TENNESSEE, 1997 U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 02-4294 by Gerard J. Gonthier This document is available in pdf format:  WRIR_02_4294 (2.4 Mb)(Requires Adobe Acrobat Reader) ABSTRACT Twenty-four monitor wells screened in the shallow water-table aquifer and eight monitor wells screened in the upper part of the Memphis aquifer in the Memphis vicinity, Tennessee, were sampled as part of the Mississippi Embayment National Water-Quality Assessment Program. These samples were collected during April and May 1997, and were analyzed for turbidity, water temperature, pH, specific conductance, dissolved oxygen concentration, alkalinity, major ions, nutrients, 18 trace elements, 85 pesticides, 87 volatile organic compounds (VOCs), radioisotopes, and stable isotopes. The Memphis study area consists of 76 square miles of residential-commercial areas ranging in age from 5 to 25 years. Atrazine was the only compound in this study detected at a concentration that exceeded a U.S. Environmental Protection Agency primary drinking-water standard. Manganese, iron, and dissolved solids concentrations in water from some wells exceeded secondary standards. At least one pesticide was detected in water from 24 of 32 wells. The most frequently detected pesticides in water from the monitor wells were atrazine, simazine, and metolachlor. At least one VOC was detected in water from 31 of 32 wells. The most frequently detected VOCs in water from the wells were carbon disulfide, chloroform, m- and pxylenes, tetrachloroethene, and toluene. Water from 17 wells was a sodium bicarbonate type water; water from 12 wells was a calciummagnesium bicarbonate type water; water from 2 wells was a sodium chloride type water; water from 1 well was a sodium mixed anion type water. Based on both tritium and chlorofluorocarbon data, the average age of water from the monitor wells in the Memphis study area was estimated to range from 10 to more than 43 years old. Occurrence of VOCs increased with increasing urban land use. TABLE OF CONTENTSAbstract Introduction Purpose and Scope Acknowledgments Environmental Setting Climate Physiography Geology Hydrogeology Land Use Pesticide Application and Toxic Release Inventory Methods of Study Design of Ground-Water Sampling Network Well Drilling and Sediment-Sample Collection Collection of Land-Use Information Ground-Water Sample Collection and Analysis Quality-Assurance Data Collection Statistical Methods of Data Analysis Ground-Water Quality Field Measurements Major Ions Nutrients Trace Elements Pesticides Volatile Organic Compounds Radioisotopes (Radium-226 and Radon-222) Age Dating Constituents (Tritium and Chlorofluorocarbons) Stable Isotopes Land Use Surrounding Monitor Wells and Ground-Water Quality Summary Selected Reference Appendix 1. Sediment-Characteristics Data Appendix 2. Water-Quality Data Appendix 3. Quality-Assurance Data FIGURES 1. Map showing locations of monitoring wells in the recently developed residential and commercial areas, Memphis vicinity, Tennessee, 1997 2. Map showing hydrogeology and physiography in the Memphis vicinity, Tennessee, 1997 3. Map showing land use in the Memphis vicinity, Tennessee, 1992 4. Piper diagram of the chemistry of water from 32 monitor wells, Memphis vicinity, Tennessee, 1997 5. Graph showing relation of bromide concentration with chloride concentrations in water from 32 monitor wells, Memphis vicinity, Tennessee, 1997 6. Graphs showing the relations of detections of different volatile organic compounds per well and m- and p-xylene concentrations with depth to water below land surface at 24 monitor wells screened in the shallow water-table aquifer, Memphis vicinity, Tennessee, 1997 7. Graph showing relation of carbon disulfide concentration with chromium concentrations in water from 32 monitor wells, Memphis vicinity, Tennessee, 1997 8. Graph showing relation of relative hydrogen isotopic ratio with oxygen isotopic ratios in water from 12 monitor wells, Memphis vicinity, Tennessee, 1997, and water from17 public-supply wells screened in the deep Tertiary aquifers in the Mississippi Embayment, 1996 9. Graphs showing relations of chloride and sum of volatile-organic-compound concentrations in water with urban land-use percentages within 500 meters of 24 monitor wells screened in the shallow water-table aquifer, Memphis vicinity, Tennessee, 1997 10. Graph showing relation of bicarbonate concentration in water with forest land-use percentages within 500 meters of 24 monitor wells screened in the shallow water-table aquifer, Memphis vicinity, Tennessee, 1997 TABLES 1. Relation of local geologic units within the Memphis vicinity, Tennessee, East Gulf Coastal Plain, with hydrogeologic units 2. Estimated pesticide application to agricultural land in Shelby County, Tennessee, 1995 3. Summary of toxic release inventory for Memphis and Millington, Tennessee, 1995 4. Selected information for the monitor wells sampled in recently developed residential and commercial areas, Memphis vicinity, Tennessee, 1997 5. Laboratory analysis methods for measured sediment properties and water-quality constituents, Memphis vicinity, Tennessee, 1996-97 6. Summary of field-measurement data for water from 32 monitor wells, Memphis vicinity, Tennessee, 1997 7. Summary of major-ion concentrations in water from 32 monitor wells, Memphis vicinity, Tennessee, 1997 8. Summary of nutrient concentrations in water from 32 monitor wells and primary drinking-water standards, Memphis vicinity, Tennessee, 1997 9. Summary of trace-element concentrations in water from 32 monitor wells and primary drinking-water standards, Memphis vicinity, Tennessee, 1997 10. Summary of pesticide concentrations in water from 32 monitor wells and primary drinking-water standards, Memphis vicinity, Tennessee, 1997 11. Pesticide occurrence in water from 32 monitor wells in Memphis vicinity (ground water) compared to water in Fletcher Creek (surface water), Memphis, Tennessee, 1996-97 12. Summary of volatile-organic-compound concentrations in water from 32 monitor wells and primary drinking-water standards, Memphis vicinity, Tennessee, 1997 13. Names of volatile organic compounds used in this report and International Union of Pure and Applied Chemistry conventional names 14. Summary of volatile-organic-compound concentrations in water from five resampled monitor wells, Memphis vicinity, Tennessee, Spring 1997 and September 1998 15. Volatile-organic-compound occurrence in water from 32 monitor wells, Memphis vicinity (ground water), compared to water in Fletcher Creek (surface water), Memphis, Tennessee, 1996-97 16. Chlorofluorocarbon, tritium concentrations, and interpreted chlorofluorocarbon recharge dates in water from 10 monitor wells, Memphis vicinity, Tennessee, September 1998 17. Land-use percent within a 50-meter radius of each well, Memphis vicinity, Tennessee, January 1997 18. Land-use percent within a 500-meter radius of each well, Memphis vicinity, Tennessee, January 1997 Water Resources of Mississippi |