Reductive Dechlorination
of Chlorinated Ethenes Under Oxidation-
Reduction Conditions and Potentiometric Surfaces in Two
Trichloroethene-Contaminated Zones at the Double Eagle and
Fourth Street Superfund Sites in Oklahoma City, Oklahoma
Prepared under interagency agreement
with the
U.S. Environmental Protection Agency
U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2004-5050 version 2 ONLINE ONLY
By Christopher L. Braun
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Contents
Abstract
Introduction
Purpose and Scope
Subsurface Description of the Study Area
Data Collection and Analytical Methods
Reductive Dechlorination of Chlorinated Ethenes Under Oxidation-Reduction Conditions
Volatile Organic Compounds
Dissolved Oxygen
Nitrate and Nitrite
Ferrous Iron and Total Iron
Sulfate and Sulfide
Methane
Potentiometric Surfaces
Summary
References Cited
Figures
1. |
Map showing location of study area, Oklahoma City, Oklahoma | |
2. |
Map showing locations of Double Eagle Refining Superfund site and Fourth Street Abandoned Refinery Superfund site within the study area | |
3a–b. |
Sequence diagrams showing concentrations of trichloroethene (TCE), cis-dichloroethene (cis-DCE), vinyl chloride, ethene, and chloride in the: | |
a. |
Shallow zone of the Garber-Wellington aquifer, February 2002 (except ethene, December 2001) | |
b. |
Deep zone of the Garber-Wellington aquifer, February 2002 | |
4a–b. |
Sequence diagrams showing concentrations of dissolved oxygen, nitrate, ferrous iron, sulfate, and methane in the: | |
a. |
Shallow zone of the Garber-Wellington aquifer, December 2001 | |
b. |
Deep zone of the Garber-Wellington aquifer, February–March 2002 | |
5. |
Map showing potentiometric surface and flow directions in the shallow zone of the Garber-Wellington aquifer, Double Eagle Refining Superfund site and Fourth Street Abandoned Refinery Superfund site, December 2001 | |
6. |
Map showing potentiometric surface and flow directions in the deep zone of the Garber-Wellington aquifer, Double Eagle Refining Superfund site and Fourth Street Abandoned Refinery Superfund site, February 2002 |
Tables
1. |
General information for wells sampled in the Garber-Wellington aquifer at the Double Eagle Refining Superfund site and the Fourth Street Abandoned Refinery Superfund site, Oklahoma City, Oklahoma, by the U.S. Geological Survey and the Oklahoma Department of Environmental Quality, December 2001 and February–March 2002 |
2. |
Selected constituents, methods, and procedures used to evaluate natural attenuation processes in ground water at the Double Eagle Refining Superfund site and the Fourth Street Abandoned Refinery Superfund site, Oklahoma City, Oklahoma |
3. |
Analytical results for volatile organic compounds and chloride from well-water samples at the Double Eagle Refining Superfund site and the Fourth Street Abandoned Refinery Superfund site, Oklahoma City, Oklahoma, collected by the Oklahoma Department of Environmental Quality, February 2002 |
4. |
Historical analytical results for selected volatile organic compounds from well-water samples at the Double Eagle Refining Superfund site and the Fourth Street Abandoned Refinery Superfund site, Oklahoma City, Oklahoma, collected by the Oklahoma Department of Environmental Quality |
5. |
Analytical results for selected properties and inorganic constituents from well-water samples at the Double Eagle Refining Superfund site and the Fourth Street Abandoned Refinery Superfund site, Oklahoma City, Oklahoma, collected by the U.S. Geological Survey, December 2001 and February–March 2002 |
6. |
Analytical results for carbon dioxide, methane, ethane, and ethene from well-water samples at the Double Eagle Refinery Superfund site and the Fourth Street Abandoned Refinery Superfund site, Oklahoma City, Oklahoma, collected by the U.S. Geological Survey, December 2001 and February–March 2002 |
7. |
Measured and computed data from wells used to construct potentiometric surfaces at the Double Eagle Refining Superfund site and the Fourth Street Abandoned Refinery Superfund site, Oklahoma City, Oklahoma, December 2001 and February 2002 |
Vertical Datum
Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29).
Abstract
The Double Eagle Refining Superfund site and the Fourth Street Abandoned Refinery Superfund site are in northeast Oklahoma City, Oklahoma, adjacent to one another. The Double Eagle facility became a Superfund site on the basis of contamination from lead and volatile organic compounds; the Fourth Street facility on the basis of volatile organic compounds, pesticides, and acid-base neutral compounds. The study documented in this report was done to investigate whether reductive dechlorination of chlorinated ethenes under oxidation-reduction conditions is occurring in two zones of the Garber-Wellington aquifer (shallow zone 30–60 to 75 feet below land surface, deep zone 75 to 160 feet below land surface) at the sites; and to construct potentiometric surfaces of the two water-yielding zones to determine the directions of ground-water flow at the sites. The presence in some wells of intermediate products of reductive dechlorination, dichloroethene and vinyl chloride, is an indication that reductive dechlorination of trichloroethene is occurring. Dissolved oxygen concentrations (less than 0.5 milligram per liter) indicate that consumption of dissolved oxygen likely had occurred in the oxygen-reducing microbial process associated with reductive dechlorination. Concentrations of nitrate and nitrite nitrogen (generally less than 2.0 and 0.06 milligrams per liter, respectively) indicate that nitrate reduction probably is not a key process in either aquifer zone. Concentrations of ferrous iron greater than 1.00 milligram per liter in the majority of wells sampled indicate that iron reduction is probable. Concentrations of sulfide less than 0.05 milligram per liter in all wells indicate that sulfate reduction probably is not a key process in either zone. The presence of methane in ground water is an indication of strongly reducing conditions that facilitate reductive dechlorination. Methane was detected in all but one well. In the shallow zone in the eastern part of the study area, ground water flowing from the northwest and south coalesces in a potentiometric trough, then moves westward and ultimately northwestward. In the western part of the study area, ground water in the shallow zone flows northwest. In the deep zone in the eastern part of the study area, ground water generally flows northwestward; and in the western part of the study area, ground water in the deep zone generally flows northward.
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