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In cooperation with the U.S. Air Force, Aeronautical Systems Center,
Environmental Management Directorate, Wright-Patterson Air Force Base, Ohio

Analyses and Estimates of Hydraulic Conductivity From Slug Tests in Alluvial Aquifer Underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas

U.S. Geological Survey Scientific Investigations Report 2004-5225

By Natalie A. Houston and Christopher L. Braun


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Abstract

This report describes the collection, analyses, and distribution of hydraulic-conductivity data obtained from slug tests completed in the alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas, during October 2002 and August 2003 and summarizes previously available hydraulic-conductivity data. The U.S. Geological Survey, in cooperation with the U.S. Air Force, completed 30 slug tests in October 2002 and August 2003 to obtain estimates of horizontal hydraulic conductivity to use as initial values in a ground-water-flow model for the site. The tests were done by placing a polyvinyl-chloride slug of known volume beneath the water level in selected wells, removing the slug, and measuring the resulting water-level recovery over time. The water levels were measured with a pressure transducer and recorded with a data logger. Hydraulic-conductivity values were estimated from an analytical relation between the instantaneous displacement of water in a well bore and the resulting rate of head change. Although nearly two-thirds of the tested wells recovered 90 percent of their slug-induced head change in less than 2 minutes, 90-percent recovery times ranged from 3 seconds to 35 minutes. The estimates of hydraulic conductivity range from 0.2 to 200 feet per day. Eighty-three percent of the estimates are between 1 and 100 feet per day.

Contents

Abstract

Introduction

Study Area

Previous Studies and Available Data

Slug Tests

Theory

Equipment

Data Collection

Analyses and Estimates of Hydraulic Conductivity

Summary

References

Plate

1.   Map showing locations of study area and wells in which slug tests were completed to estimate hydraulic conductivity in alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas

Figures

1.   Map showing location of study area and distribution of trichloroethene (TCE) plume in alluvial aquifer underlying Air Force Plant 4 (AFP4) and Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB), Fort Worth, Texas, August 2003
2.   Generalized west-to-east hydrogeologic section through study area, Air Force Plant 4 (AFP4) and Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB), Fort Worth, Texas
3–5.   Graphs showing:
  3.   Slug-induced water-level change (normalized) relative to time from slug-test data collected at Air Force Plant 4 (AFP4) and Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB), Fort Worth, Texas, October 2002
  4.   Slug-induced water-level change (normalized) relative to time from slug-test data collected at Air Force Plant 4 (AFP4) and Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB), Fort Worth, Texas, August 2003
  5.   Frequency distribution of hydraulic-conductivity values obtained from analyses of slug-test data collected from wells in alluvial aquifer, Air Force Plant 4 (AFP4) and Naval Air Station-Joint Reserve Base Carswell Field (NAS–JRB), Fort Worth, Texas

Tables

1.   Geologic and hydrologic characteristics of hydrogeologic units underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas
2.   Locations and results of pre-2002 aquifer and slug tests used to estimate hydraulic conductivity in alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas
3.   Diameters of wells and dimensions of slugs used to estimate hydraulic conductivity in alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas
4.   Location and site-characteristic data for wells used to estimate hydraulic conductivity in alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas
5.   Summary of hydraulic-conductivity estimates, slug discrepancies, and 90-percent recovery times for wells in alluvial aquifer underlying Air Force Plant 4 and Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas

 

 

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