In cooperation with the Southern Division Naval Facilities Engineering Command
Use of Borehole Geophysical Logs for Improved Site Characterization at Naval Weapons Industrial Reserve Plant, Dallas, Texas
By Roberto Anaya, Christopher L. Braun, and Eve L. Kuniansky
U.S. Geological Survey
Water-Resources Investigations Report 00–4150
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CONTENTS
Abstract
Introduction
Purpose and Scope
Description of Study Area
Approach
Use of Borehole Geophysical Logs
Gamma-Ray Log Processing and Analysis
Cone-Penetrometer Test Log Processing and Analysis
Electromagnetic-Induction Log Processing and Analysis
Site Characterization
Summary
References
PLATES
1–3. Maps showing:
1. Lines of section and logged well locations, Naval Weapons Industrial Reserve Plant, Dallas, Texas
(pdf 26" X 20.5", 348 KB)2. Lithologic sections A–A', C–C', D–D', and F–F' at Naval Weapons Industrial Reserve Plant, Dallas, Texas
(pdf 24" X 20", 534 KB)3. Lithologic sections G–G', L–L', M–M', P–P', Q–Q', and R–R' at Naval Weapons Industrial Reserve Plant, Dallas, Texas
(pdf 36" X 20", 661 KB)
FIGURES
1. Map showing location of the study area
2. Graph showing comparison of natural, filtered, and classified gamma-ray log data
3. Graph showing comparison of a cone-penetrometer test (CPT) log and a nearby gamma-ray log
4. Boxplots showing range and distribution of conductivity for wells with no detected contaminants
TABLE
1. Statistics for clay-content sediment classes in uncontaminated areas of the shallow alluvial aquifer
VERTICAL DATUM, ABBREVIATIONS, AND ACRONYMS
Sea level: In this report “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929)—a geodetic datum derived from a general adjustment of the first-order level nets of both the United States and Canada, formerly called Sea Level Datum of 1929.
Abbreviations:
cm/s, centimeter per second
cps, counts per second
°F, degree Fahrenheit
ft, foot
ft/s, foot per second
gal/d, gallon per day
gal/min, gallon per minute
in., inch
µg/L, microgram per liter
mi, mile
mS/m, millisiemens per meter
Acronyms:
CPT, cone-penetrometer test
EM, electromagnetic
GOCO, government-owned, contractor-operated
NAS, Naval Air Station
NWIRP, Naval Weapons Industrial Reserve Plant
RCRA, Resource Conservation and Recovery Act
RFI, RCRA Facility Investigation
SOUTHDIV, Southern Division Naval Facilities Engineering Command
TCE, trichloroethene
USGS, U.S. Geological Survey
Abstract
A shallow alluvial aquifer at the Naval Weapons Industrial Reserve Plant near Dallas, Texas, has been contaminated by organic solvents used in the fabrication and assembly of aircraft and aircraft parts. Natural gamma-ray and electromagnetic-induction log data collected during 1997 from 162 wells were integrated with existing lithologic and cone-penetrometer test log data to improve characterization of the subsurface alluvium at the site. The alluvium, consisting of mostly fine-grained, low-permeability sediments, was classified into low, intermediate, and high clay-content sediments on the basis of the gamma-ray logs. Low clay-content sediments were interpreted as being relatively permeable, whereas high clay-content sediments were interpreted as being relatively impermeable. Gamma-ray logs, cone-penetrometer test logs, and electromagnetic-induction logs were used to develop a series of intersecting sections to delineate the spatial distribution of low, intermediate, and high clay-content sediments and to delineate zones of potentially contaminated sediments.
The sections indicate three major sedimentary units in the shallow alluvial aquifer at NWIRP. The lower unit consists of relatively permeable, low clay-content sediments and is absent over the southeastern and northwestern part of the site. Permeable zones in the complex, discontinuous middle unit are present mostly in the western part of the site. In the eastern and southeastern part of the site, the upper unit has been eroded away and replaced by fill material. Zones of potentially contaminated sediments are generally within the uppermost clay layer or fill material. In addition, the zones tend to be local occurrences.
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