U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2007–3074

September 2007

Contamination in Fractured-Rock Aquifers—Research at the 

former Naval Air Warfare Center, West Trenton, New Jersey

The U.S. Geological Survey and cooperators are studying chlorinated solvents in a fractured sedimentary rock aquifer underlying the 

former Naval Air Warfare Center 

(NAWC), West Trenton, New Jersey. 

Fractured-rock aquifers are common 

in many parts of the United States 

and are highly susceptible to contamination, particularly at industrial 

sites. Compared to “unconsolidated” 

aquifers, there can be much more 

uncertainty about the direction and 

rate of contaminant migration and 

about the processes and factors 

that control chemical and microbial 

transformations of contaminants. 

Research at the NAWC is improving understanding of the transport 

and fate of chlorinated solvents in 

fractured-rock aquifers and will 

compare the effectiveness of different strategies for contaminant 

remediation.

contamination in fractured sedimentary rock 

underlying the former Naval Air Warfare 

Center (NAWC) in West Trenton, New 

Jersey.

Why Is There Contamination at the 

NAWC?

The U.S. Navy tested jet engines at the 

NAWC in West Trenton, New Jersey, from 

the mid-1950s until the late 1990s. Fractured 

bedrock at the site was contaminated with 

trichloroethylene (TCE) used during the 

engine testing operations. It is likely that 

heavier-than-water TCE has flowed vertically 

downward and in the down-dip direction of 

the fractured sedimentary rocks. An aqueousphase plume of dissolved TCE has flowed 

along the strike and in the up-dip directions. 

There is evidence of microbial transformation (biodegradation) of TCE to dichloroethylene (DCE) and vinyl chloride (VC). 

Investigations of the ground-water contamination at the site began in the late 1980s, and 

a pump and treat operation that has successfully limited offsite migration was started in 

the mid-1990s.

Multidisciplinary and Cooperative 

Research

One objective of the cooperative research 

at the NAWC is to improve scientific understanding of physical, chemical, and microbial 

processes affecting the transport and fate of 

chlorinated solvents, including the role of 

dense nonaqueous phase liquid (DNAPL) 

TCE as a long-term source. The research 

also will develop methods for cost effective 

subsurface monitoring and will compare 

different strategies for cleaning up TCE in 

fractured-rock aquifers. The NAWC site was 

chosen for this research because the general 

hydrogeologic framework is well defined 

and the site contains extensive contamination 

over a range of geochemical conditions.

In 1993, the USGS began studies at the 

NAWC in cooperation with the U.S. Navy. 

The U.S. Navy tested jet engines at the Naval Air Warfare Center, West Trenton, New Jersey, 

from the mid-1950s until the late 1990s. Fractured bedrock at the site was contaminated with 

trichloroethylene (TCE) used during the testing operations.

Complex Fractured-Rock Aquifers and 

Contamination

Toxic chemicals such as chlorinated 

solvents pose a serious threat to the Nation’s 

ground-water resources. Many industrial 

sites in the Eastern United States are located 

in the Piedmont physiographic region, 

where fractured rock aquifers are common. 

Improper disposal methods, leaking tanks 

and pipes, and chemical spills have contaminated fractured-rock aquifers in and around 

these sites.

The restoration and protection of 

ground-water quality at these sites depend 

on knowledge of the physical, chemical, and 

microbiological processes that affect the 

transport and fate of these toxic chemicals. 

To gain this knowledge, the U.S. Geological 

Survey (USGS) Toxic Substances Hydrology 

Program, in cooperation with other Federal, 

State, and private-sector organizations, is 

conducting multidisciplinary research on 

Rock cores from a borehole at the NAWC, 

showing the dipping mudstone strata that are 

pathways for ground-water flow and chemical 

transport.
Printed on recycled paper

In 2001, The USGS began the multidisciplinary, cooperative research effort that currently also involves scientists from the Navy, 

New Jersey Department of Environmental 

Protection and New Jersey Geological Survey, and universities and other research institutions. A 2005 biostimulation and bioaugmentation study was conducted with private 

sector researchers—Geosyntec Consultants 

and ECOR Solutions—on behalf of the Navy. 

Research support is provided by the USGS, 

the Navy, the U.S. Environmental Protection 

Agency (EPA), and the U.S. Department of 

Defense Strategic Environmental Research 

and Development Program (SERDP), operated in partnership with EPA and the U.S. 

Department of Energy.

Finding Pathways in Fractured Rock

Understanding contaminant fate in fractured rock and designing effective remediation 

strategies first requires identifying the paths 

of fluid and chemical movement. USGS, in 

cooperation with the U.S. Navy, has characterized in detail the hydrogeologic framework at 

the NAWC, revealing the three-dimensional 

distribution of dipping sequences of fissile, 

laminated, and massive mudstones, primarily 

by correlation of core and gamma-ray logs. 

Hydraulically active pathways for ground-water flow and chemical transport are identified 

using cross-hole flow logging, aquifer tests, 

and tracer tests. Current research for understanding the hydrogeologic framework and 

finding flow paths includes surface geophysical surveys, investigations of a fault zone, and 

numerical ground-water flow modeling. 

Monitoring Contaminants, Geochemistry, 

and Remediation

In fractured rock, contaminant concentrations and water geochemistry can vary dramatically over short distances, and remediation strategies need to account for this spatial 

variability. At the NAWC, the spatial and 

temporal distribution of TCE, DCE, and VC 

contamination has been characterized using 

about 100 wells open to short intervals of the 

bedrock and overlying saprolite (thoroughly 

weathered clay-rich rock). Concentrations of 

these contaminants indicate partial biodegradation of TCE to DCE and VC, but rates are 

low and degradation appears to be stalled in 

many locations. Ongoing pumping removes 

contaminated ground water, but the concentration of TCE in many wells remains high, 

suggesting that some contaminant mass lies in 

low-permeability fractures and in the primary 

porosity of unfractured rock. 

Planned monitoring research includes 

characterizing contaminant mass in the rock 

matrix and investigating rates of TCE and 

bacteria migration between hydraulically 

conductive fractures and low-permeability 

zones using tracer tests and low-cost diffusion 

sampling methods.

Investigating Biodegradation

The natural biodegradation of TCE under 

anaerobic conditions often does not progress 

beyond DCE and VC. Bioaugmentation is 

a method of enhancing this process, and 

involves injecting into the subsurface a viable 

biological culture and a sufficient amount 

of electron donor (an energy source for the 

microorganisms) to support the reductive 

dechlorination of TCE and its daughter products. Beginning in July 2005, a pilot scale bioaugmentation system was implemented at the 

NAWC by the U.S. Navy. Substantial reduction of TCE, DCE, and VC has been observed. 

Current research on biodegradation includes 

characterization of bacteria and processes that 

control degradation by using measurements of 

DNA, hydrogen and other gas concentrations, 

and carbon isotopes of TCE, DCE, and VC.

Synthesizing Multidisciplinary Data and 

Predicting Contaminant Fate

Numerical reactive transport models are 

powerful tools for synthesizing multidisciplinary data at contaminant sites and for 

predicting contaminant fate and remediation. 

Planned reactive transport modeling (RTM) 

at the NAWC will include the simulation 

of contaminant transport between the rock 

matrix and fractures, geochemical reactions, and biodegradation. RTM will build 

on ground-water flow modeling currently 

underway to help identify flow and transport 

paths. RTM will be used to synthesize physical and biogeochemical data; better understand the processes controlling transport and 

biodegradation of TCE, DCE, and VC; and 

simulate contaminant mass removal rates by 

pump and treat, monitored natural attenuation, and enhanced biodegradation. Comparison of the mass removal rates of contaminants by these three methods in fractured 

rock underlying the NAWC will provide 

valuable information towards designing costeffective, efficient remediation strategies for 

many other fractured-rock aquifers across 

the Nation.

Daniel J. Goode, Claire R. Tiedeman,

Pierre J. Lacombe, Thomas E. Imbrigiotta, 

Allen M. Shapiro, and Francis H. Chapelle

Conceptual diagram of contaminant transport 

and degradation processes in fractured mudstone. TCE, trichloroethylene; DCE, dichloroethylene; VC, vinyl chloride; DNAPL, dense 

nonaqueous phase liquid.

Edited by James W. Hendley II

Layout by David R. Jones

COOPERATING ORGANIZATIONS

U.S. Navy

U.S. Environmental Protection Agency

U.S. Department of Defense, Strategic Environmental Research and Development Program

New Jersey Department of Environmental Protection

New Jersey Geological Survey 

Michigan State University

Rutgers University

Temple University

University of Kansas

University of South Carolina

Geosyntec Consultants

ECOR Solutions

For more information contact:

 djgoode or tiedeman@usgs.gov

http://toxics.usgs.gov/sites/nawc_page.html

http://nj.usgs.gov/nawc/

This Fact Sheet and any updates

to it are available online at

http://pubs.usgs.gov/fs/2007/3074/

Low-cost diffusion samplers are placed in 

wells at the NAWC to monitor contaminant 

concentrations and geochemistry. 

DOC

Fe(OH)3 FeCO3

Mudstone

TCE

DCE

DNAPL

dissolution

TCE

DCE

Clay 

TCE

Sorption

Bioaugmentation

VC

Fe+2 Ca+2

Organic

Degradation

(TEAPS: O2, Fe(III)

organics 

CO2, CH4, H2

Matrix

diffusion

SO4, CO2 DOC)

Fe(OH)3 FeCO3

Mudstone

TCE

DCE

DNAPL

dissolution

TCE

DCE

Clay 

TCE

Sorption

Bioaugmentation

VC

Fe+2 Ca+2

Organic

Degradation

(TEAPS: O2, Fe(III)

organics 

CO2, CH4, H2

Matrix

diffusion

SO4, CO2)