&EPA
United States
Environmental Protection
Agency
Solid Waste And
Emergency Response
(OS-240)
EPA/540/8-91/024
September 1991
PB92-963228
National
Priorities
List Sites:
DE LAWARE
Printed on Recycled Paper
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Publication #9200.5-709A
September 1991
NATIONAL PRIORITIES LIST SITES:
Delaware
U.nvr
Region 5, Library (""
77 West Jackson l\j.
Chicago, SL 60bu4-
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Office of Emergency & Remedial Response
Office of Program Management
Washington, DC 20460
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If you wish to purchase copies of any additional State volumes contact:
National Technical Information Service (NTIS)
U.S. Department of Commerce
5285 Port Royal Road
Springfield, VA 22161
(703) 487-4650
The National Overview volume, Superfund: Focusing on the Nation at Large (1991),
may be ordered as PB92-963253.
The complete set of the overview documents, plus the 49 state reports may be ordered
as PB92-963253.
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TABLE OF CONTENTS
Page
Introduction:
A Brief Overview 1
Super fund:
How Does the Program Work to Clean Up Sites? 5
The Volume:
How to Use the State Book 13
NPL Sites:
In the State of Delaware 17
The NPL Report:
Progress to Date 19
The NPL Fact Sheets:
Summary of Site Activities 21
Appendix A: Glossary:
Terms Used in the Fact Sheets 65
Appendix B: Repositories of
Site Information 81
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INTRODUCTION
WHY THE SUPERFUND
PROGRAM?
As the 1970s came to a close, a series of
headline stories gave Americans a
look at the dangers of dumping indus-
trial and urban wastes on the land. First there
was New York's Love Canal. Hazardous
waste buried there over a 25-year period
contaminated streams and soil, and endangered
the health of nearby residents. The result:
evacuation of several hundred people. Then
the leaking barrels at the Valley of the Drums
in Kentucky attracted public attention, as did
the dioxin-tainted land and water in Times
Beach, Missouri.
In all these cases, human health and the envi-
ronment were threatened, lives were disrupted,
and property values were reduced. It became
increasingly clear that there were large num-
bers of serious hazardous waste problems that
were falling through the cracks of existing
environmental laws. The magnitude of these
emerging problems moved Congress to enact
the Comprehensive Environmental Response,
Compensation, and Liability Act in 1980.
CERCLA commonly known as Superfund
was the first Federal law established to deal
with the dangers posed by the Nation's hazard-
ous waste sites.
After Discovery, the Problem
Intensified
Few realized the size of the problem until the
Environmental Protection Agency (EPA)
began the process of site discovery and site
evaluation. Not hundreds, but thousands of
potential hazardous waste sites existed, and
they presented the Nation with some of the
most complex pollution problems it had ever
faced.
Since the Superfund program began, hazard-
Brief
Overview
ous waste has surfaced as a major environ-
mental concern in every part of the United
States. It wasn't just the land that was con-
taminated by past disposal practices. Chemi-
cals in the soil were spreading into the ground-
water (a source of drinking water for many)
and into streams, lakes, bays, and wetlands.
Toxic vapors contaminated the air at some
sites, while improperly disposed or stored
wastes threatened the health of the surrounding
community and the environment at others.
The EPA Identified More than 1,200
Serious Sites
The EPA has identified 1,245 hazardous waste
sites as the most serious in the Nation. These
sites comprise the National Priorities List; sites
targeted for cleanup under Super-fund. But
site discoveries continue, and the EPA esti-
mates that, while some will be deleted after
lengthy cleanups, this list, commonly called
the NPL, will continue to grow by approxi-
mately 50 to 100 sites per year, potentially
reaching 2,100 sites by the year 2000.
THE NATIONAL CLEANUP
EFFORT IS MUCH MORE THAN
THE NPL
From the beginning of the program, Congress
recognized that the Federal government could
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INTRODUCTION
not and should not address all environmental
problems stemming from past disposal prac-
tices. Therefore, the EPA was directed to set
priorities and establish a list of sites to target.
Sites on the NPL (1,245) thus are a relatively
small subset of a larger inventory of potential
hazardous waste sites, but they do comprise
the most complex and compelling cases. The
EPA has logged more than 35,000 sites on its
national inventory of potentially hazardous
waste sites and assesses each site within one
year of being logged.
THE EPA IS MAKING PROGRESS
ON SITE CLEANUP
The goal of the Superfund program is to tackle
immediate dangers first and then move through
the progressive steps necessary to eliminate
any long-term risks to public health and the
environment.
Superfund responds immediately to sites
posing imminent threats to human health and
the environment at both NPL sites and sites not
on the NPL. The purpose is to stabilize,
prevent, or temper the effects of a release of
hazardous substances, or the threat of one, into
the environment. These might include tire
fires or transportation accidents involving the
spill of hazardous chemicals. Because they
reduce the threat a site poses to human health
and the environment, immediate cleanup
actions are an integral part of the Superfund
program.
Immediate response to imminent threats is one
of Superfund's most noted achievements.
Where imminent threats to the public or
environment were evident, the EPA has initi-
ated or completed emergency actions that
attacked the most serious threats of toxic
exposure in more than 2,700 cases.
The ultimate goal for a hazardous waste site on
the NPL is a permanent solution to an environ-
mental problem that presents a serious threat
to the public or the environment. This often
requires a long-term effort. The EPA has
aggressively accelerated its efforts to perform
these long-term cleanups of NPL sites. More
cleanups were started in 1987, when the
Superfund law was amended, than in any
previous year. By 1991, construction had
started at more than four times as many sites as
in 1986! Of the sites currently on the NPL,
more than 500 nearly half have had
construction cleanup activity. In addition,
more than 400 more sites presently are in the
investigation stage to determine the extent of
site contamination and to identify appropriate
cleanup remedies. Many other sites with
cleanup remedies selected are poised for the
start of cleanup construction activity. In
measuring success by "progress through the
cleanup pipeline," the EPA clearly is gaining
momentum.
THE EPA MAKES SURE
CLEANUP WORKS
The EPA has gained enough experience in
cleanup construction to understand that envi-
ronmental protection does not end when the
remedy is in place. Many complex technolo-
gies like those designed to clean up ground-
water must operate for many years in order
to accomplish their objectives.
The EPA's hazardous waste site managers are
committed to proper operation and mainte-
nance of every remedy constructed. No matter
who has been delegated responsibility for
monitoring the cleanup work, the EPA will
assure that the remedy is carefully followed
and that it continues to do its job.
Likewise, the EPA does not abandon a site
even after the cleanup work is done. Every
five years, the Agency reviews each site where
residues from hazardous waste cleanup still
remain to ensure that public and environmental
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INTRODUCTION
health are being safeguarded. The EPA will
correct any deficiencies discovered and will
report to the public annually on all five-year
reviews conducted that year.
CITIZENS HELP SHAPE
DECISIONS
Superfund activities also depend upon local
citizen participation. The EPA's job is to
analyze the hazards and to deploy the experts,
but the Agency needs citizen input as it makes
choices for affected communities.
Because the people in a community where a
Superfund site is located will be those most
directly affected by hazardous waste problems
and cleanup processes, the EPA encourages
citizens to get involved in cleanup decisions.
Public involvement and comment does influ-
ence EPA cleanup plans by providing valuable
information about site conditions, community
concerns, and preferences.
The State and U.S. Territories volumes and the
companion National overview volume provide
general Superfund background information
and descriptions of activities at each NPL site.
These volumes clearly describe what the
problems are, what the EPA and others partici-
pating in site cleanups are doing, and how we,
as a Nation, can move ahead in solving these
serious problems.
USING THE STATE AND
NATIONAL VOLUMES TOGETHER
To understand the big picture on hazardous
waste cleanup, citizens need to hear about both
environmental progress across the country and
the cleanup accomplishments closer to home.
Citizens also should understand the challenges
involved in hazardous waste cleanup and the
decisions we must make, as a Nation, in
finding the best solutions.
The National overview, Superfund: Focusing
on the Nation at Large (1991), contains impor-
tant information to help you understand the
magnitude and challenges facing the
Superfund program, as well as an overview of
the National cleanup effort. The sections
describe the nature of the hazardous waste
problem nationwide, threats and contaminants
at NPL sites and their potential effects on
human health and the environment, vital roles
of the various participants in the cleanup
process, the Superfund program's successes in
cleaning up the Nation's serious hazardous
waste sites, and the current status of the NPL.
If you did not receive this overview volume,
ordering information is provided in the front of
this book.
This volume compiles site summary fact sheets
on each State or Territorial site being cleaned
up under the Superfund program. These sites
represent the most serious hazardous waste
problems in the Nation and require the most
complicated and costly site solutions yet
encountered. Each book gives a "snapshot" of
the conditions and cleanup progress that has
been made at each NPL site. Information
presented for each site is current as of April
1991. Conditions change as our cleanup
efforts continue, so these site summaries will
be updated annually to include information on
new progress being made.
To help you understand the cleanup accom-
plishments made at these sites, this volume
includes a description of the process for site
discovery, threat evaluation, and long-term
cleanup of Superfund sites. This description,
How Does the Program Work to Clean Up
Sites?, will serve as a reference point from
which to review the cleanup status at specific
sites. A glossary defining key terms as they
apply to hazardous waste management and site
cleanup is included as Appendix A in the back
of this book.
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SUPERFUND
The diverse problems posed by hazard-
ous waste sites have provided the EPA
with the challenge to establish a consis-
tent approach for evaluating and cleaning up
the Nation's most serious sites. To do this, the
EPA has had to step beyond its traditional role
as a regulatory agency to develop processes
and guidelines for each step in these techni-
cally complex site cleanups. The EPA has
established procedures to coordinate the
efforts of its Washington, D.C. Headquarters
program offices and its front-line staff in ten
Regional Offices, with the State and local
governments, contractors, and private parties
who are participating in site cleanup. An
important part of the process is that any time
How Does the
Program Work
to Clean Up
Sites?
THREE-STEP SUPERFUND PROCESS
STEP1
Discover site and
determine whether
an emergency
exists *
STEP 2
Evaluate whether a
site is a serious threat
to public health or
environment
STEPS
Perform long-term
cleanup actions on
the most serious
hazardous waste
sites in the Nation
* Emergency actions are performed whenever needed in this three-step process.
during cleanup, work can be led by the EPA
or the State or, under their monitoring, by
private parties who are potentially responsible
for site contamination.
The process for discovery of the site, evalu-
ation of threat, and the long-term cleanup of
Superfund sites is summarized in the follow-
ing pages. The phases of each of these steps
are highlighted within the description. The
flow diagram above provides a summary of the
three-step process.
Although this book provides a current "snap-
shot" of site progress made only by emergency
actions and long-term cleanup actions at
Superfund sites, it is important to understand
the discovery and evaluation process that leads
to identifying and cleaning up these most
serious uncontrolled or abandoned hazardous
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SUPERFUND
waste sites in the Nation. The discovery and
evaluation process is the starting point for this
summary description of Superfund involve-
ment at hazardous waste sites.
STEP 1: SITE DISCOVERY AND
EMERGENCY EVALUATION
How does the EPA learn about
potential hazardous waste sites?
Site discovery occurs in a number of ways.
Information comes from concerned citizens.
People may notice an odd taste or foul odor in
their drinking water or see half-buried leaking
barrels; a hunter may come across a field
where waste was dumped illegally. There may
be an explosion or fire, which alerts the State
or local authorities to a problem. Routine
investigations by State and local governments
and required reporting and inspection of
facilities that generate, treat, store, or dispose
of hazardous waste also help keep the EPA
informed about actual or potential threats of
hazardous substance releases. All reported
sites or spills are recorded in the Superfund
inventory (CERCLIS) for further investigation
to determine whether they will require cleanup.
What happens If there is an imminent
danger?
As soon as a potential hazardous waste site is
reported, the EPA determines whether there is
an emergency requiring an immediate cleanup
action. If there is, they act as quickly as
possible to remove or stabilize the imminent
threat. These short-term emergency actions
range from building a fence around the con-
taminated area to keep people away, or tempo-
rarily relocating residents until the danger is
addressed, to providing bottled water to resi-
dents while their local drinking water supply is
being cleaned up or physically removing
wastes for safe disposal.
However, emergency actions can happen at
any time an imminent threat or emergency
warrants them. For example, if leaking barrels
are found when cleanup crews start digging in
the ground or if samples of contaminated soils
or air show that there may be a threat of fire or
explosion, an immediate action is taken.
STEP 2: SITE THREAT EVALUATION
If there isn't an imminent danger, how
does the EPA determine what, if any,
cleanup actions should be taken?
Even after any imminent dangers are taken
care of, in most cases, contamination may
remain at the site. For example, residents may
have been supplied with bottled water to take
care of their immediate problem of contami-
nated well water, but now it's time to deter-
mine what is contaminating the drinking water
supply and the best way to clean it up. The
EPA may determine that there is no imminent
danger from a site, so any long-term threats
need to be evaluated. In either case, a more
comprehensive investigation is needed to
determine if a site poses a serious, but not
imminent, danger and whether it requires a
long-term cleanup action.
Once a site is discovered and any needed
emergency actions are taken, the EPA or the
State collects all available background infor-
mation not only from their own files, but also
from local records and U.S. Geological Survey
maps. This information is used to identify the
site and to perform a preliminary assessment of
its potential hazards. This is a quick review of
readily available information to answer the
questions:
Are hazardous substances likely to be
present?
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SUPERFUND
How are they contained?
How might contaminants spread?
How close is the nearest well, home, or
natural resource area such as a wetland
or animal sanctuary?
What may be harmed the land,
water, air, people, plants, or animals?
Some sites do not require further action be-
cause the preliminary assessment shows that
they do not threaten public health or the envi-
ronment. But even in these cases, the sites
remain listed in the Superfund inventory for
record-keeping purposes and future reference.
Currently, there are more than 35,000 sites
maintained in this inventory.
If the preliminary assessment
shows a serious threat may exist,
what's the next step?
Inspectors go to the site to collect additional
information to evaluate its hazard potential.
During this site inspection, they look for
evidence of hazardous waste, such as leaking
drums and dead or discolored vegetation.
They may take some samples of soil, well
water, river water, and air. Inspectors analyze
the ways hazardous materials could be pollut-
ing the environment, such as runoff into
nearby streams. They also check to see if
people (especially children) have access to
the site.
How does the EPA use the results of
the site inspection?
Information collected during the site inspection
is used to identify the sites posing the most
serious threats to human health and the envi-
ronment. This way, the EPA can meet the
requirement that Congress gave them to use
Superfund monies only on the worst hazardous
waste sites in the Nation.
To identify the most serious sites, the EPA
developed the Hazard Ranking System (HRS).
The HRS is the scoring system the EPA uses to
assess the relative threat from a release or a
potential release of hazardous substances from
a site to surrounding groundwater, surface
water, air, and soil. A site score is based on
the likelihood that a hazardous substance will
be released from the site, the toxicity and
amount of hazardous substances at the site, and
the people and sensitive environments poten-
tially affected by contamination at the site.
Only sites with high enough health and envi-
ronmental risk scores are proposed to be added
to the NPL. That's why 1,245 sites are on the
NPL, but there are more than 35,000 sites in
the Superfund inventory. Only NPL sites can
have a long-term cleanup paid for from
Superfund, the national hazardous waste trust
fund. Superfund can, and does, pay for emer-
gency actions performed at any site, whether
or not it's on the NPL.
Why are sites proposed to the NPL?
Sites proposed to the NPL have been evaluated
through the scoring process as the most serious
problems among uncontrolled or abandoned
hazardous waste sites in the U.S. In addition, a
site will be proposed to the NPL if the Agency
for Toxic Substances and Disease Registry
issues a health advisory recommending that
people be moved away from the site. The NPL
is updated at least once a year, and it's only
after public comments are considered that
these proposed worst sites officially are added
to the list.
Listing on the NPL does not set the order in
which sites will be cleaned up. The order is
influenced by the relative priority of the site's
health and environmental threats compared to
other sites, and such factors as State priorities,
engineering capabilities, and available tech-
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SUPERFUND
nologies. Many States also have their own list
of sites that require cleanup; these often contain
sites that are not on the NPL and are scheduled
to be cleaned up with State money. And, it
should be noted again that any emergency
action needed at a site can be performed by the
Superfund, whether or not a site is on the NPL.
A detailed description of the current progress in
cleaning up NPL sites is found in the section of
the 1991 National overview volume entitled
Cleanup Successes: Measuring Progress.
How do people find out whether the
EPA considers a site a national
priority for cleanup under the
Superfund Program?
All NPL sites, where Superfund is responsible
for cleanup, are described in the State and
Territorial volumes. The public also can find
out whether other sites, not on the NPL, are
being addressed by the Superfund program by
calling their Regional EPA office or the Super-
fund Hotline at the numbers listed in this book.
STEP 3: LONG-TERM CLEANUP
ACTIONS
After a site is added to the NPL, what
are the steps to cleanup?
The ultimate goal for a hazardous waste site on
the NPL is a permanent, long-term cleanup.
Since every site presents a unique set of chal-
lenges, there is no single all-purpose solution.
A five-phase "remedial response" process is
used to develop consistent and workable
solutions to hazardous waste problems across
the Nation:
1. Remedial Investigation: investigate in
detail the extent of the site contamination
2. Feasibility Study: study the range of
possible cleanup remedies
3. Record of Decision or ROD: decide
which remedy to use
4. Remedial Design: plan the remedy
5. Remedial Action: carry out the remedy
This remedial response process is a long-term
effort to provide a permanent solution to an
environmental problem that presents a serious
threat to the public or environment.
The first two phases of a long-term cleanup are
a combined remedial investigation and feasibil-
ity study (RI/FS) that determine the nature and
extent of contamination at the site and identify
and evaluate cleanup alternatives. These
studies may be conducted by the EPA or the
State or, under their monitoring, by private
parties.
Like the initial site inspection described earlier,
a remedial investigation involves an examina-
tion of site data in order to better define the
problem. However, the remedial investigation
is much more detailed and comprehensive than
the initial site inspection.
A remedial investigation can best be described
as a carefully designed field study. It includes
extensive sampling and laboratory analyses to
generate more precise data on the types and
quantities of wastes present at the site, the type
of soil and water drainage patterns, and specific
human health and environmental risks.
The result of the remedial investigation is
information that allows the EPA to select the
cleanup strategy that is best suited to a particu-
lar site or to determine that no cleanup is
needed.
Placing a site on the NPL does not necessarily
mean that cleanup is needed. It is possible for
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SUPERFUND
a site to receive an HRS score high enough to
be added to the NPL, but not ultimately require
cleanup actions. Keep in mind that the purpose
of the scoring process is to provide a prelimi-
nary and conservative assessment of potential
risk. During subsequent site investigations, the
EPA may find either that there is no real threat
or that the site does not pose significant human
health or environmental risks.
How are cleanup alternatives
identified and evaluated?
The EPA or the State or, under their monitor-
ing, private parties identify and analyze spe-
cific site cleanup needs based on the extensive
information collected during the remedial
investigation. This analysis of cleanup alterna-
tives is called a feasibility study.
Since cleanup actions must be tailored exactly
to the needs of each individual site, more than
one possible cleanup alternative is always
considered. After making sure that all potential
cleanup remedies fully protect human health
and the environment and comply with Federal
and State laws, the advantages and disadvan-
tages of each cleanup alternative are compared
carefully. These comparisons are made to
determine their effectiveness in the short and
long term, their use of permanent treatment
solutions, and their technical feasibility and
cost.
To the maximum extent practicable, the rem-
edy must be a permanent solution and must use
treatment technologies to destroy principal site
contaminants. Remedies such as containing the
waste on site or removing the source of the
problem (like leaking barrels) often are consid-
ered effective. Often, special pilot studies are
conducted to determine the effectiveness and
feasibility of using a particular technology to
clean up a site. Therefore, the combined
remedial investigation and feasibility study can
take between 10 and 30 months to complete,
depending on the size and complexity of the
problem.
Does the public have a say in the
final cleanup decision?
Yes. The Superfund law requires that the
public be given the opportunity to comment on
the proposed cleanup plan. Their concerns are
considered carefully before a final decision is
made.
The results of the remedial investigation and
feasibility study, which also point out the
recommended cleanup choice, are published in
a report for public review and comment. The
EPA or the State encourages the public to
review the information and take an active role
in the final cleanup decision. Fact sheets and
announcements in local papers let the commu-
nity know where they can get copies of the
study and other reference documents concern-
ing the site. Local information repositories,
such as libraries or other public buildings, are
established in cities and towns near each NPL
site to ensure that the public has an opportunity
to review all relevant information and the
proposed cleanup plans. Locations of informa-
tion repositories for each NPL site described in
this volume are given in Appendix B.
The public has a minimum of 30 days to
comment on the proposed cleanup plan after it
is published. These comments can be written
or given verbally at public meetings that the
EPA or the State are required to hold. Neither
the EPA nor the State can select the final
cleanup remedy without evaluating and provid-
ing written answers to specific community
comments and concerns. This "responsiveness
summary" is part of the EPA's write-up of the
final remedy decision, called the Record of
Decision, or ROD.
The ROD is a public document that explains
the cleanup remedy chosen and the reason it
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SUPERFUND
was selected. Since sites frequently are large
and must be cleaned up in stages, a ROD may
be necessary for each contaminated resource or
area of the site. This may be necessary when
contaminants have spread into the soil, water,
and air and affect such sensitive areas as
wetlands, or when the site is large and cleaned
up in stages. This often means that a number
of remedies, using different cleanup technolo-
gies, are needed to clean up a single site.
If every cleanup action needs to be
tailored to a site, does the design
ofthe remedy need to be tailored,
too?
Yes. Before a specific cleanup action is carried
out, it must be designed in detail to meet
specific site needs. This stage of the cleanup is
called the remedial design. The design phase
provides the details on how the selected rem-
edy will be engineered and constructed.
Projects to clean up a hazardous waste site may
appear to be like any other major construction
project but, in fact, the likely presence of
combinations of dangerous chemicals demands
special construction planning and procedures.
Therefore, the design of the remedy can take
anywhere from six months to two years to
complete. This blueprint for site cleanup
includes not only the details on every aspect of
the construction work, but a description of the
types of hazardous wastes expected at the site,
special plans for environmental protection,
worker safety, regulatory compliance, and
equipment decontamination.
Once the design is completed,
how long does it take to actually
clean up the site, and how much
does it cost?
The time and cost for performing the site
cleanup, called the remedial action, are as
varied as the remedies themselves. In a few
cases, the only action needed may be to remove
drums of hazardous waste and to decontami-
nate them, an action that takes limited time and
money. In most cases, however, a remedial
action may involve different and expensive
cleanup measures that can take a long time.
For example, cleaning polluted groundwater or
dredging contaminated river bottoms can take
several years of complex engineering work
before contamination is reduced to safe levels.
Sometimes the selected cleanup remedy de-
scribed in the ROD may need to be modified
because of new contaminant information
discovered or difficulties that were faced
during the early cleanup activities. Taking into
account these differences, each remedial
cleanup action takes an average of 18 months
to complete and ultimately costs an average of
$26 million to complete all necessary cleanup
actions at a site.
Once the cleanup action is
completed, is the site
automatically "deleted" from the
NPL?
No. The deletion of a site from the NPL is
anything but automatic. For example, cleanup
of contaminated groundwater may take up to
20 years or longer. Also, in some cases, long-
term monitoring of the remedy is required to
ensure that it is effective. After construction of
certain remedies, operation and maintenance
(e.g., maintenance of ground cover, groundwa-
ter monitoring, etc.), or continued pumping and
treating of groundwater may be required to
ensure that the remedy continues to prevent
future health hazards or environmental damage
and ultimately meets the cleanup goals speci-
fied in the ROD. Sites in this final monitoring
or operational stage of the cleanup process are
designated as "construction complete."
It's not until a site cleanup meets all the goals
and monitoring requirements of the selected
10
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SUPERFUND
remedy that the EPA can officially propose the
site for deletion from the NPL, and it's not
until public comments are taken into consid-
eration that a site actually can be deleted from
the NPL. All sites deleted from the NPL and
sites with completed construction are included
in the progress report found later in this book.
Can a site be taken off the NPL if
no cleanup has taken place?
Yes. But only if further site investigation
reveals that there are no threats present at the
site and that cleanup activities are not neces-
sary. In these cases, the EPA will select a "no
action" remedy and may move to delete the
site when monitoring confirms that the site
does not pose a threat to human health or the
environment.
In other cases, sites may be "removed" from
the NPL if new information concerning site
cleanup or threats show that the site does not
warrant Superfund activities.
A site may be removed if a revised HRS
scoring, based on updated information, results
in a score below the minimum for NPL sites.
A site also may be removed from the NPL by
transferring it to other appropriate Federal
cleanup authorities, such as RCRA, for further
cleanup actions.
Removing sites for technical reasons or trans-
ferring sites to other cleanup programs pre-
serves Superfund monies for the Nation's most
pressing hazardous waste problems where no
other cleanup authority is applicable.
Can the EPA make parties
responsible for the contamination
pay?
Yes. Based on the belief that "the polluters
should pay," after a site is placed on the NPL,
the EPA makes a thorough effort to identify
and find those responsible for causing con-
tamination problems at a site. Although the
EPA is willing to negotiate with these private
parties and encourages voluntary cleanup, it
has the authority under the Superfund law to
legally force those potentially responsible for
site hazards to take specific cleanup actions.
All work performed by these parties is closely
guided and monitored by the EPA and must
meet the same standards required for actions
financed through the Superfund.
Because these enforcement actions can be
lengthy, the EPA may decide to use Superfund
monies to make sure a site is cleaned up
without unnecessary delay. For example, if a
site presents an imminent threat to public
health and the environment or if conditions at a
site may worsen, it could be necessary to start
the cleanup right away. Those responsible for
causing site contamination are liable under the
law (CERCLA) for repaying the money the
EPA spends in cleaning up the site.
Whenever possible, the EPA and the Depart-
ment of Justice use their legal enforcement
authorities to require responsible parties to pay
for site cleanups, thereby preserving Superfund
resources for emergency actions and for sites
where no responsible parties can be identified.
11
-------
THE VOLUME
The site fact sheets presented in this
book are comprehensive summaries
that cover a broad range of information.
The fact sheets describe hazardous
waste sites on the NPL and their locations, as
well as the conditions leading to their listing
("Site Description"). The summaries list the
types of contaminants that have been discov-
ered and related threats to public and ecologi-
cal health ("Threats and Contaminants").
"Cleanup Approach" presents an overview of
the cleanup activities completed, underway, or
planned. The fact sheets conclude with a brief
synopsis of how much progress has been made
in protecting public health and the environ-
ment. The summaries also pinpoint other
actions, such as legal efforts to involve pollut-
ers responsible for site contamination and
community concerns.
The fact sheets are arranged in alphabetical
order by site name. Because site cleanup is a
dynamic and gradual process, all site informa-
tion is accurate as of the date shown on the
bottom of each page. Progress always is being
made at NPL sites, and the EPA periodically
will update the site fact sheets to reflect recent
actions and will publish updated State vol-
umes. The following two pages show a ge-
neric fact sheet and briefly describe the infor-
mation under each section.
HOW CAN YOU USE THIS STATE
BOOK?
You can use this book to keep informed about
the sites that concern you, particularly ones
close to home. The EPA is committed to
involving the public in the decision making
process associated with hazardous waste
cleanup. The Agency solicits input from area
residents in communities affected by Super-
fund sites. Citizens are likely to be affected
not only by hazardous site conditions, but also
by the remedies that combat them. Site clean-
How to Use
the State
Book
ups take many forms and can affect communi-
ties in different ways. Local traffic may be
rerouted, residents may be relocated, tempo-
rary water supplies may be necessary.
Definitive information on a site can help
citizens sift through alternatives and make
decisions. To make good choices, you must
know what the threats are and how the EPA
intends to clean up the site. You must under-
stand the cleanup alternatives being proposed
for site cleanup and how residents may be
affected by each one. You also need to have
some idea of how your community intends to
use the site in the future, and you need to
know what the community can realistically
expect once the cleanup is complete.
The EPA wants to develop cleanup methods
that meet community needs, but the Agency
only can take local concerns into account if it
understands what they are. Information must
travel both ways in order for cleanups to be
effective and satisfactory. Please take this
opportunity to learn more, become involved,
and assure that hazardous waste cleanup at
"your" site considers your community's
concerns.
13
-------
THE VOLUME
NPL LISTING HISTORY
Dates when the site was
Proposed, made Final, and
Deleted from the NPL.
SITE NAME
STATE
EPA ID* ABCOOOOOOO
*""SUsDescription
EPA REGION XX
CONGRESSIONAL DIST XX
COUNTY NAME
LOCATION
Other Name*:
SITE RESPONSIBILITY
Identifies the Federal, State,
and/or potentially respon-
sible parties that are taking
responsibility for cleanup
actions at the site.
Site Responsibility:
NPL Listing History
Proposed: xttnx
Fink
reats and Contaminants
Cleanup Approach
Response Action Status
Site Facts:,
Environmental Progress
ENVIRONMENTAL PROGRESS
A summary of the actions to reduce the threats to
nearby residents and the surrounding environment;
progress towards cleaning up the site and goals of
the cleanup plan are given here.
14
-------
THE VOLUME
SITE DESCRIPTION
This section describes the location and history of the site. It includes descrip-
tions of the most recent activities and past actions at the site that have con-
tributed to the contamination. Population estimates, land usages, and nearby
resources give readers background on the local setting surrounding the site.
THREATS AND CONTAMINANTS
The major chemical categories of site contamination are noted, as well as
which environmental resources are affected. Icons representing each of the
affected resources (may include air, groundwater, surface water, soil, and
contamination to environmentally sensitive areas) are included in the margins
of this section. Potential threats to residents and the surrounding environ-
ments arising from the site contamination also are described.
CLEANUP APPROACH
This section contains a brief overview of how the site is being cleaned up.
RESPONSE ACTION STATUS
Specific actions that have been accomplished or will be undertaken to clean
up the site are described here. Cleanup activities at NPL sites are divided
into separate phases, depending on the complexity and required actions at the
site. Two major types of cleanup activities often are described: initial,
immediate, or emergency actions to quickly remove or reduce imminent
threats to the community and surrounding areas; and long-term remedial
phases directed at final cleanup at the site. Each stage of the cleanup strategy
is presented in this section of the summary. Icons representing the stage of
the cleanup process (initial actions, site investigations, EPA selection of the
cleanup remedy, engineering design phase, cleanup activities underway, and
completed cleanup) are located in the margin next to each activity descrip-
tion.
SITE FACTS
Additional information on activities and events at the site are included in this
section. Often details on legal or administrative actions taken by the EPA to
achieve site cleanup or other facts pertaining to community involvement with
the site cleanup process are reported here.
15
-------
THE VOLUME
The "icons," or symbols, accompanying the text allow the reader to see at a glance which envi-
ronmental resources are affected and the status of cleanup activities at the site.
Icons in the Threats and
Contaminants Section
Contaminated Groundwater resources
in the Contaminated Groundwater in
the vicinity or underlying the site.
(Groundwater is often used as a
drinking water source.)
Contaminated Surface Water and
Sediments on or near the site. (These
include lakes, ponds, streams, and
rivers.)
Contaminated Air in the vicinity of
the site. (Air pollution usually is
periodic and involves contaminated
dust particles or hazardous gas emis-
sions.)
Contaminated Soil and Sludges on or
near the site. (This contamination
category may include bulk or other
surface hazardous wastes found on the
site.)
Threatened or contaminated Environ-
mentally Sensitive Areas in the vicin-
ity of the site. (Examples include
wetlands and coastal areas or critical
habitats.)
Icons in the Response Action
Status Section
Initial Actions have been taken or are
underway to eliminate immediate
threats at the site.
Site Studies at the site to determine the
nature and extent of contamination are
planned or underway.
Remedy Selected indicates that site
investigations have been concluded,
and the EPA has selected a final
cleanup remedy for the site or part of
the site.
Remedy Design means that engineers
are preparing specifications and
drawings for the selected cleanup
technologies.
Cleanup Ongoing indicates that the
selected cleanup remedies for the
contaminated site, or part of the site,
currently are underway.
Cleanup Complete shows that all
cleanup goals have been achieved for
the contaminated site or part of the
site.
Environmental Progress summa-
rizes the activities taken to date to
protect human health and to clean
up site contamination.
16
-------
NPL SITES
The State of
Delaware
Located in EPA Region 3, Delaware is the second smallest state in the nation, covering 2,045
square miles. The State is located on the Atlantic coastal plain, slopes to a near- sea-level plain
and gradually rises to the Piedmont plateau in the north. According to the 1990 Census,
Delaware's population grew by 12% between 1980 and 1990, and currently has approximately
666,200 residents, ranking 46th in U.S. populations. Principal state industries and goods include
chemistry, agriculture, finance, poultry, shellfish, tourism, auto assembly, and food processing.
A variety of agricultural products, livestock, nylon, apparel, luggage, and railroad and aircraft
equipment are produced in Delaware.
How Many NPL Sites
Are in the State of Delaware?
Proposed
Final
Deleted
0
20
_i
21
Where Are the NPL Sites Located?
Congressional District 1
21 sites
What Type of Sites Are on the NPL
in the State of Dealware?
# of sites
7
4
1
1
1
1
6
type of sites
Municipal & Industrial Landfills
Chemicals & Allied Products
Rubber & Plastics
Lumber & Wood
Electroplating
Federal Facility
Others (Metals & allied products, recycler,
disposal facility, coal gasification plant,
degreaser facility).
17
April 1991
-------
NPL SITES
How Are Sites Contaminated and What Are the Principal* Chemicals?
20--
16-1-
4 --
I
I
GW Soil
SW
Sad Solid &
Liquid
Wastes
Contamination Area
Groundwater: Heavy metals (inor-
ganics) and volatile organic compounds
(VOCs).
Soil, Solid and Liquid Wastes:
Heavy metals (inorganics), volatile
organic compounds (VOCs), creosote
(organics), and polychlorinated biphe-
nyls (PCBs).
Surface Water and Sediment:
Heavy metals (inorganics) volatile
organic compounds (VOCs), creosote
(organics) polychlorinated biphenyls
(PCBs), petrochemicals, and pesticides.
Appear at 15% or more sites
Where Are the Sites in the Super-fund Cleanup Process?1
8
Sites
with I
Studies
Underway
3
Sites
with
Remedy
Selected
3
Sites
with
Remedy
Design
4
Sites
with
Cleanup
Ongoing
Sites
with
Construction
Complete
1
Deleted
Sites
In addition to the activities described above, initial actions have been taken at 12 sites as interim
cleanup measures.
'Cleanup status reflects phases of site activities rather than administrative accomplishments.
April 1991
18
-------
THE NPL REPORT
The following Progress Report lists all
sites currently on, or deleted from, the
NPL and briefly summarizes the status
of activities for each site at the time this
report was prepared. The steps in the Super-
fund cleanup process are arrayed across the
top of the chart, and each site's progress
through these steps is represented by an arrow
indicating the current stage of cleanup.
Progress
To Date
Large and complex sites often are organized
into several cleanup stages. For example,
separate cleanup efforts may be required to
address the source of the contamination,
hazardous substances in the groundwater, and
surface water pollution, or to clean up differ-
ent areas of a large site. In such cases, the
chart portrays cleanup progress at the site's
most advanced stage, reflecting the status of
site activities rather than administrative
accomplishments.
An arrow in the "Initial Response" cate-
gory indicates that an emergency cleanup or
initial action has been completed or currently
is underway. Emergency or initial actions are
taken as an interim measure to provide im-
mediate relief from exposure to hazardous site
conditions or to stabilize a site to prevent
further contamination.
A final arrow in the "Site Studies"
category indicates that an investigation to
determine the nature and extent of the
contamination at the site currently is ongoing.
A final arrow in the "Remedy Selection"
category means that the EPA has selected the
final cleanup strategy for the site. At the few
sites where the EPA has determined that
initial response actions have eliminated site
contamination, or that any remaining
contamination will be naturally dispersed
without further cleanup activities, a "No
Action" remedy is selected. In these cases, the
arrows are discontinued at the "Remedy
Selection" step and resume in the
"Construction Complete" category.
A final arrow at the "Remedial Design"
stage indicates that engineers currently are
designing the technical specifications for the
selected cleanup remedies and technologies.
A final arrow in the "Cleanup Ongoing"
column means that final cleanup actions have
been started at the site and currently are
underway.
A final arrow in the "Construction
Complete" category is used only when all
phases of the site cleanup plan have been
performed, and the EPA has determined that no
additional construction actions are required at
the site. Some sites in this category currently
may be undergoing long-term operation and
maintenance or monitoring to ensure that the
cleanup actions continue to protect human
health and the environment.
A check in the "Deleted" category indicates
that the site cleanup has met all human health
and environmental goals and that the EPA has
deleted the site from the NPL.
Further information on the activities and
progress at each site is given in the site "Fact
Sheets" published in this volume.
19
April 1991
-------
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THE NPL FACT SHEETS
Summary
of Site
Activities
are
EPA REGION 3
21
April 1991
-------
Who Do I Call with Questions?
The following pages describe each NPL site in Delaware, providing specific
information on threats and contaminants, cleanup activities, and environmen-
tal progress. Should you have questions, please call the EPA's Region 3
Office in Philadelphia, Pennsylvania or one of the other offices listed below:
EPA Region 3 Superfund Community Relations Office (215) 597-9905
EPA Region 3 Superfund Office (215) 597-8132
EPA Superfund Hotline (800) 424-9346
EPA Headquarters Public Information Center (202) 260-2080
Delaware Superfund Office (302) 323-4540
April 1991 22
-------
ABMV PRPPIf (I EPAREGION3
Mrtivii onccrv i x CONGRESSIONAL DIST. 01
I AIMrtCII I I X New Castle County
l_A\|MUrlLL \-^\ 2 miles southwest of New Castle
DELAWARE \ M0dl-:N7r5n,
! /^\ Llangollen Landfill
EPA ID# DED980494496 K N Delaware Sand & Gravel
Llangollen Army Creek Landfills
Site Description
The Army Creek Landfill site occupies approximately 47 acres of a 64-acre parcel. It was used
as a landfill for municipal and industrial wastes from 1960 to 1968. During that 8-year period,
about 2 million cubic yards of refuse were landfilled. The site previously was used as a sand and
gravel quarry. Approximately 30% of the waste lies below the seasonal high water table. Army
Creek, which forms the southern and eastern border of the site, flows into the Delaware River
about 1 mile east of the site. Groundwater contamination was discovered in a nearby residential
well in 1972. After studies were conducted by New Castle County, which identified alcohols
and acidic compounds in leachate, wells were installed to prevent the movement of groundwater
toward public water supply wells. The water pumped out of these wells currently is discharged
untreated to Army Creek and Army Pond. About 3,370 people live within 1 mile of the site,
which is in a largely rural and light industrial area. Llangollen Estates, a residential
development, is several hundred feet beyond the southern edge of the site. An estimated 130,000
people living within 3 miles of the site are served by groundwater supplies. Another NPL site,
the Delaware Sand and Gravel Landfill, is located immediately across from Army Creek to the
east of the site.
Site Responsibility: This site is being addressed through
Federal and potentially responsible
parties' actions.
NPL LISTING HISTORY
Proposed Date: 10/01/81
Final Date: 09/08/83
Threats and Contaminants
Volatile organic compounds (VOCs), such as benzene and dichloroethane, and
heavy metals including chromium and mercury are found in monitoring wells,
recovery wells, groundwater, and soils. The surface water of Army Creek
contains contamination from cadmium, chromium, mercury, iron, and zinc.
People working or trespassing on the site could be exposed to contaminants in the
soil by direct contact or accidentally ingesting it, by inhaling contaminants in the
air, or by drinking contaminated groundwater. Methane gas escaping from the
landfill could cause injuries if an explosion occurred.
23 April 1991
-------
Cleanup Approach
This site is being addressed in three stages: emergency actions and two long-term remedial
phases focusing on source control and cleanup of the entire site.
Response Action Status
Emergency Actions: Tires on the site caught fire and threatened to ignite nearby
hazardous wastes. The fire was extinguished by New Castle County, and the EPA
provided emergency technical support and air monitoring during the fire control efforts.
New Castle County installed a groundwater recovery system designed to capture contaminated
groundwater. This series of downgradient pumping wells is designed to prevent the contamination
plume from reaching the source of the drinking water supply. Pumping has separated contamination
from the water supply and has eliminated further migration of the plume into the drinking water
source.
Source Control: Control of the source of contamination of the site will include: (1)
installation of a multi-layer cap over the landfill; (2) continued operation of the
downgradient recovery well network; and (3) evaluation of the cap system and the
groundwater recovery network for five years by monitoring well water levels and by pumping water
and checking the water quality. Five years after the cap is in place, an evaluation will be carried out
to determine if installation of upgradient controls are necessary. At the same time, the monitoring
strategy for well water levels, pumping rates, and water quality will be re-evaluated. The EPA has
completed design of the technical specifications for the selected remedy, and cleanup activities are
scheduled to begin in 1991.
Entire Site: A detailed study of the nature and extent of contamination and treatment
alternatives for the water being pumped from the groundwater recovery wells was
completed in 1990, leading to the final selection of a groundwater treatment remedy for
recovery wells. The treatment remedy consists of the construction and operation of a water
treatment facility, which will treat recovered groundwater before discharge to surface water. In
addition, a plan for long-term monitoring will be developed with respect to groundwater, surface
water, sediments, and associated wetlands.
Site Facts: On September 18, 1990, 18 potentially responsible parties signed a Consent Decree to
implement the cleanup actions at the site and to reimburse the EPA for past response costs.
Environmental Progress
The County's installation of groundwater recovery wells to prevent the spread of contamination into
the drinking water supply and the EPA's emergency response to the on-site fire have made the Army
Creek site safer while it awaits the completion of the selected treatment remedies.
April 1991 24 ARMY CREEK LANDFILL
-------
CHEM-SOLV, INC.
DELAWARE
EPAID#DED980714141
Site Description
EPA REGION 3
CONGRESSIONAL DIST. 01
Kent County
Cheswold
The 1 1/2-acrc Chem-Solv, Inc. site served as a small solvent distillation facility beginning in
1982. The facility recycled waste solvents by placing a drum on an electric coil heater, which
distilled the solvents into a second drum. The contents of the second drum were filtered into a
third drum, and the distilled residues were stored on site. In 1984, an explosion and fire at the
site destroyed the entire distillation facility. Witnesses observed fluids flowing off a concrete
pad into the soil. After the fire, the State conducted studies at the upper Columbia Aquifer,
which is adjacent to the site, where high concentrations of volatile organic chemicals (VOCs)
were found in both the upper and lower zones of the aquifer. An occupied 3-unit apartment
building is located on the site. About 5,500 residents live and are served by private wells within
3 miles of the site.
Site Responsibility:
This site is being addressed through a
combination of Federal, State, and
potentially responsible parties' actions.
NPL LISTING HISTORY
Proposed Date: 06/10/88
Final Date: 08/30/90
Threats and Contaminants
The groundwater and soil are contaminated with VOCs from site waste disposal
practices. The primary threat to human health is drinking the contaminated
groundwater. However, at this time, the levels of contaminants reported in
residential wells are within acceptable drinking water standards. There is little
potential for exposure to any contamination from on-site soil because it was
excavated and air-stripped in 1985.
25
April 1991
-------
Cleanup Approach
This site is being addressed in two stages: immediate actions and a long-term remedial phase
focusing on cleanup of the entire site.
Response Action Status
Immediate Actions: In 1985, the State excavated and treated contaminated soil using a
process that passes air through the soil to remove VOCs. Also, in 1985, the State started
to recover and treat the VOCs in the upper Columbia Aquifer, using an air stripping
system. The air stripping process used by the State reduced contamination to levels that permitted
the soil to be returned to the excavated area.
Entire Site: A group of parties potentially responsible for the site contamination
currently is conducting an investigation into the nature and extent of the contamination at
the site. The investigation will define the contaminants and will recommend alternatives
for the final cleanup. The investigation is planned to be completed in 1993.
Site Facts: In 1984 and 1985, the State of Delaware issued orders to one of the potentially
responsible parties to cease operations immediately, monitor groundwater, and remove all
contaminated soil; however, no actions were taken. In 1988, a Consent Order was signed by the
potentially responsible parties, the EPA, and the State, requiring the parties to conduct an
investigation into the contamination at the site.
Environmental Progress
By removing VOCs from the soil and from the upper Columbia Aquifer, the State has eliminated
immediate threats and has reduced the potential for exposure to hazardous materials. These actions
have made the Chem-Solv, Inc. site safer while the potentially responsible parties complete their
investigation and begin final cleanup activities.
April 1991 26 CHEM-SOLVJNC.
-------
COKER'S < EPA REGION 3
1 CONGRESSIONAL DIST. 01
SANITATION SERVI
LANDFILLS
DELAWARE <**-' i-*»«
EPA ID# DED980704860
Site Description
The two Coker's Sanitation Service Landfills cover 25 acres near Cheswold. Coker's Landfill #1
covers 10 acres, and Coker's Landfill #2 covers the remaining 15 acres. The landfills were used for
disposal of latex rubber waste sludges from what is now the Reichold Chemicals, Inc. plant. Coker's
Landfill #1, operated from 1962 until 1976, consists of an unknown number of unlined trenches.
Coker's Landfill #2 was used under a State solid waste disposal permit from 1976 to 1980 and
consists of 51 lined trenches, a leachate collection and monitoring system, and a groundwater
monitoring system. The landfills overlie two groundwater systems: the Columbia Aquifer, which is
a water table aquifer and the Cheswold Aquifer, which is a deeper artesian aquifer. Approximately
4,000 people live within a 3-mile radius of the site, and two farms are adjacent to the landfills.
Site Responsibility: This site is being addressed through NPL LISTING HISTORY
Federal and potentially responsible
parties' actions.
Proposed Date: 04/01/85
Final Date: 07/01/87
Threats and Contaminants
On-site groundwater, sludge, leachate, and soil contamination consists of heavy metals
including iron, volatile organic compounds (VOCs) such as ethyl benzene and toluene,
and acrolein from the latex rubber wastes. Off-site monitoring wells have shown the
presence of acrolein and ethyl benzene. Potential risks to health are direct contact with
contaminated substances on site or accidental ingestion of groundwater or leachate.
However, considering the remote, rural, partially restricted nature of the site, the potential
for public contact with contaminants on or near the site appears to be slight. There is a
potential for contaminants to move off site to the nearby surface water and to the water
table aquifer and the regional aquifer, both of which supply city water. Area wetlands
also are potentially threatened, since drainage from Coker's Landfill #1 runs through a
wetlands area to the Willis Branch of the Leipsic River, and Coker's Landfill #2 partially
is bordered by wetlands.
27 April 1991
-------
Cleanup Approach
The site is being addressed in two stages: immediate actions and a long-term remedial phase
focusing on cleanup of the entire site.
Response Action Status
Immediate Actions: In 1989, buried drums and a bin were discovered by geomagnetic
surveys during the site investigation conducted by the parties potentially responsible for
the site contamination. These materials were excavated, overpacked, and incinerated, and
the area was fenced for protective purposes.
Entire Site: The soil and groundwater are the primary focal points of site cleanup. The
potentially responsible parties conducted an investigation of the drums and the entire site
to help determine the extent of remaining contamination and to identify alternative
technologies for the cleanup. In 1990, the EPA selected a cleanup remedy, which involves deed
restrictions, fencing and posting warning signs to limit access to the site, covering exposed leachate
seeps, backfilling and seeding eroded areas in Landfill #2, grouting leachate collection wells in
Landfill #2, monitoring groundwater and inspecting the landfills on an ongoing basis, and
monitoring surface water at the Willis Branch. The design activities for the remedy are expected to
begin in 1991.
Site Facts: An Administrative Order on Consent was signed in 1988 by the EPA and Reichold
Chemicals, Inc., Nabisco Brands, Inc., and Rapid American Corp. for an investigation to determine
the extent of contamination and to identify alternative technologies for the cleanup.
Environmental Progress
Fencing the area of Coker's Landfills #1 and #2 and the removal of contaminated drums have made
the site safer while the final cleanup remedy is awaiting design.
April 1991 28 COKER'S SANITATION SERVICE LANDFILLS
-------
DELAWARE CITY m EPA REGION 3
*-**-"« »**- vri I I 1,1 CONGRESSIONAL DIST. 01
Dl AMT ^ New Castle County
I 1_/-%IM I
2 miles west of Delaware City
DELAWARE I \ Other Name,:
EPAID#DED980551667 * A Stauffer Chemica, Co.
Site Description
The 600-acre Delaware City PVC Plant site was built in 1966 and serves as a poly vinyl chloride
(PVC) production facility. From 1967 to 1970, earthen lagoons were used to dump waste PVC.
Until the wastewater treatment plant was built in 1970, a bermed area was used to settle PVC
sludges before the wastewater was discharged. Another area was used to bury sludges from the
treatment plant and then was capped. The Columbia Formation Aquifer, which has been found to
be contaminated, is used locally as a domestic water supply, and is an important source of drinking
water in the area. There are approximately 400 people living within a mile of the site. There also
are four residences and two manufacturing operations on the site. A water service company that has
wells within 3 miles of the site serves an estimated 100,000 people.
Site Responsibility: This site is being addressed through
Federal and potentially responsible
parties' actions.
NPL LISTING HISTORY
Proposed Date: 10/01/81
Final Date: 09/01/83
Threats and Contaminants
The groundwater is contaminated with volatile organic compounds (VOCs) from the
waste disposal pits. The soil is contaminated with VOCs including vinyl chloride.
Contaminated groundwater in the drinking supply poses a health threat, and on-site
workers also may be exposed to contaminants by coming into direct contact with the
soils.
Cleanup Approach
This site is being addressed in three stages: immediate actions and two long-term remedial phases
focusing on the lagoon areas and on groundwater treatment and cleanup of the PVC storage area and
sludge pits.
29 April 1991
-------
Response Action Status
Immediate Actions: Alternate water supplies were provided to users of on-site
residential wells and off-site water supply wells to eliminate the threat from contaminated
groundwater.
Lagoon Areas: The remedies selected for cleanup of the lagoon area include:
excavating sludge and contaminated soils, selling sludge product to the maximum extent
practicable, and disposing of residuals off-site; installing a double synthetic liner in a
pond, aeration basins, and installing a tank in the off-grade batch pits; and monitoring groundwater
contamination by using test wells. The parties potentially responsible for the site contamination
have prepared the technical specifications and design for the selected cleanup. Cleanup at the lagoon
areas has started and is expected to be completed by the end of 1991. Most of the on-site sources of
contamination have been removed.
Groundwater, PVC Storage Area and Sludge Pits: This cleanup phase contains
two components: groundwater treatment and cleanup of the PVC storage area and sludge
pits. The remedies selected for groundwater contamination include: (1) installing
groundwater recovery wells at the northern and southern edges of the contaminated plume; (2)
reusing groundwater collected in plant operations or routing it through the plant's wastewater
treatment unit; (3) installing additional monitoring wells to evaluate the recovery system; and (4)
providing an alternate source of water for residents using any existing contaminated water-supply
wells. The potentially responsible parties have designed the technical specifications for the cleanup
remedy. Initial efforts to reuse groundwater collected in the plant operations or routing it through
the plant's wastewater treatment unit were unsuccessful, which prompted the installation of an air
stripper to remove contaminants. Completion of the cleanup is scheduled for mid-1991. The
remedies selected for cleaning up the PVC storage area and sludge pits include: (1) covering and
capping the areas; (2) covering the existing synthetic membrane with a drainage layer and a second
membrane; and (3) establishing a vegetative cover on topsoil. The potentially responsible parties
currently are well into construction. They have completed several ponds and have begun pumping
and treating the groundwater.
Site Facts: In 1984, the EPA and the State entered into a Consent Order with the potentially
responsible parties to perform studies of cleanup alternatives and all necessary cleanup actions to
eliminate contamination at the site. In 1987, a second agreement was reached by the EPA and the
parties that outlined the details of the cleanup design and implementation.
Environmental Progress
The provision of an alternate water supply to residents and area businesses and the start of cleanup
activities at the areas of concern at the Delaware City PVC Plant site have eliminated the potential
for exposure to contaminated groundwater. Contamination levels at the Delaware City PVC site are
being reduced as cleanup activities continue.
April 1991 30 DELEWARE CITY PVC PLANT
-------
DELAWARE SAND
GRAVEL LANDFILL
DELAWARE
EPA ID# DED000605972
EPA REGION 3
CONGRESSIONAL DIST. 01
New Castle County
2 miles southwest of the City of New Castle
Other Names:
Delaware Sand & Gravel Company Landfill
Delaware Sand & Gravel-Llangollen
Army Creek Landfills
Site Description
The 27-acre Delaware Sand & Gravel Landfill site is an inactive industrial waste landfill located
adjacent to another NPL site, the Army Creek Landfill. The site has four disposal areas, referred
to as the Drum Disposal, Inert Disposal, Ridge, and Grantham South areas. Between 1968 and
1976, the site accepted household and construction wastes and at least 7,000 drums containing
liquids and sludges from perfume, plastics, paint, and petroleum refining processes. The Drum
Disposal area is believed to be the major source of organic contamination of the groundwater. In
1984, approximately 600 drums were removed from the surface of the Drum Disposal area, and it
was then covered with soil and a vegetative cover. The Ridge area consists of contaminated soil,
storage tanks, and debris scattered on the surface. The Inert Disposal area contains various
domestic wastes, cars, trucks, and storage tanks scattered on the surface. The Grantham South
area is believed to contain inert wastes and chemical wastes. Approximately 2,000 people live
within a mile of the site. The site is located in a sparsely populated and lightly industrialized area.
Properties adjoining the site include two residences and a maintenance garage. The nearest
residence is about 30 feet from the edge of the landfill. The Llangollen Estates housing
development is about 1/2 mile southwest of the site. Underlying the landfill is the Potomac
Aquifer, which is accessed about 1 1/4 miles south of the site and is used as a public water source.
Site Responsibility:
This site is being addressed through
Federal, State, and County actions.
NPL LISTING HISTORY
Proposed Date: 10/01/81
Final Date: 09/01/83
Threats and Contaminants
The groundwater is contaminated with volatile organic compounds (VOCs) and semi-
volatile organic compounds from former disposal practices. Heavy metals including
arsenic, cadmium, chromium, lead, and mercury also have been detected in off-site
groundwater. The soil is contaminated with VOCs, polychlorinated biphenyls
(PCBs), and heavy metals. Specific contaminants detected in Army Creek include
cadmium, chromium, mercury, iron, and zinc. The greatest threat to health is
accidental ingestion of groundwater. Workers, trespassers, and nearby residents may
be exposed to contaminants in the soil and air.
31
April 1991
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Cleanup Approach
This site is being addressed in two stages: immediate actions and a long-term remedial phase
focusing on contamination at the entire site.
Response Action Status
^ Immediate Actions: To reduce the threat of groundwater contamination, New Castle
County installed a recovery system downgradient of the site to prevent contaminated water
from reaching the nearby public water supply well field. The groundwater is
decontaminated prior to being discharged to Army Creek and Army Pond. In 1984, the EPA
removed approximately 600 drums from the Drum Disposal area. Drum staging pads, consisting of
a compacted clay base for the pads and a clay dike around them to prevent contaminants from
escaping, were constructed. Drums were removed and placed in the staging cells. Air monitoring
was conducted in the work area and at the site perimeter to determine the affect of site activities on
ambient air. The flammable solids and PCB materials were bulked, drummed, and safely disposed
of. A drum shredder was used to process non-flammable solids for disposal. Shredded material was
placed in box trailers and shipped to disposal facilities. Work areas of the site were regraded,
hydroseeded, and spread with mulch.
Entire Site: The selected actions for remaining cleanup activities include: (1)
excavation and on-site incineration of approximately 36,000 tons of contaminated soil and
wastes from the Drum Disposal and Ridge areas; (2) on- or off-site disposal of residual
ash; (3) reshaping of the excavated area and establishment of a vegetative cover; (4) removal and
off-site disposal of all surface debris from the Inert area; (5) soil capping of buried, inert waste
materials; (6) construction of an approved cap over the Grantham South area; and (7) a groundwater
pump and treatment system with discharge to Army Creek and continued groundwater monitoring.
The remedy will follow a phased approach. The first phase will focus on the Grantham South area.
The second phase will focus on the Drum Disposal and Ridge areas and the Inert area. Design of the
cap for the first phase of the remedy, the Grantham South area, was completed in 1989. The remedy
is expected to be completed in 1991; the approved cap has been installed. The design of the remedy
for the Drum Disposal area and Ridge area is expected to be completed in 1993, with the remedy
being implemented shortly after. The remedy for the Inert area will follow. The groundwater
recovery system is being coordinated with activity at the neighboring Army Creek Landfill
Superfund site. Continued monitoring in the area indicates that the groundwater recovery system
has been effective in controlling the migration of contaminated groundwater.
Site Facts: In 1976, the State issued an enforcement action requiring the potentially responsible
parties to discontinue disposal activities.
Environmental Progress
Numerous cleanup activities have been completed at the Delaware Sand & Gravel Landfill site,
including fencing; removing contaminated materials; capping; air monitoring; and regrading,
hydroseeding, and spreading mulch over the Drum Disposal area. The groundwater recovery system
is controlling the spread of contamination from the site while final cleanup actions are being
completed.
April 1991 32 DELAWARE SAND & GRAVEL LANDFILL
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EPAID#DE8570024010
DOVFR S EPA REGION 3
1'V'VI"ri CONGRESSIONAL DIST. 01
AIR FORCE BASE
DELAWARE
Site Description
The 3,700-acre Dover Air Force Base (AFB) site is the base of operation for the 436th Military
Airlift Wing. The base contains 13 areas on site that were used for disposing of industrial waste. An
estimated 23,000 cubic feet of waste were disposed of from 1951 to 1970. The base's operations
generated numerous wastes, some in drums, including paints, solvents, waste fuels, and oil. These
wastes were disposed of in various on-base locations including the fire training areas. All disposal
sites are earth-covered to a depth of 3 feet, with the exception of the construction debris landfill.
Access to the site is restricted. There are approximately 1,000 people living on base, and 39,000
people living within a 3-mile radius of the site. The distance from the base to the nearest residence
is about a mile, and the site is located in a commercial and residential area that is densely populated.
The base well system serves about 3,000 people and is routinely monitored by the Air Force.
Contaminants have not been found in this system.
Site Responsibility: This site is being addressed through
Federal and State actions.
NPL LISTING HISTORY
Proposed Date: 10/01/84
Final Date: 03/13/89
Threats and Contaminants
Specific contaminants detected in on-site groundwater include cadmium and volatile
organic compounds (VOCs) from former waste disposal practices. A variety of VOCs
have been detected in off-site groundwater including trichloroethylene (TCE) and carbon
tetrachloride. VOCs also have been detected in the sediments. VOCs and heavy metals
including mercury, chromium, and cadmium have been detected in on-site stream waters.
Potential health threats include exposure to contaminated groundwater used for potable
purposes and ingestion of contaminated fish and wildlife. Direct contact with
contaminated surface water or sediments during recreational or site activities by area
residents and workers also is a concern. A nearby freshwater wetlands is threatened by
site contamination.
33 April 1991
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Cleanup Approach
This site is being addressed in four stages: initial actions and three long-term remedial phases
focusing on cleanup of Fire training Area #3, the Industrial Area, and on-site groundwater.
Response Action Status
Initial Actions: The Air Force has cleaned up the industrial waste basins and a drum
site, and has provided an alternate water supply to affected residents. A landfill and some
hazardous waste areas were excavated during the runway extension in 1988 and 1989.
Fire Training Area #3: In 1990, the Air Force selected a remedy that includes
excavating an underground storage tank and adjacent soils, as needed, and capping the
area. Design activities are underway and are expected to be completed in 1991.
Industrial Area: In 1990, the Air Force began an investigation into the nature and extent
of contamination and to identify cleanup alternatives. The area comprises source areas
including treatment units, buildings, hangars, and industrial sewer lines that are close
together. A decision on the remedy is expected in 1992. As an early action, the Air Force will
suggest source controls and interim removal of contamination floating on the water table, as well as
the removal of contaminated soils.
On-Site Groundwater: Groundwater monitoring currently is underway as part of the
ongoing site studies. In 1990, the Air Force began an investigation into the extent and
nature of groundwater contamination. A decision on the remedy in expected to be made in
1993.
Site Facts: The EPA, the Air Force, and the State of Delaware have entered into an Interagency
Agreement (IAG) for comprehensive cleanup and compliance with Federal standards. The Dover
Air Force Base also is participating in the Installation Restoration Program, a specially funded
program established by the Department of Defense (DoD) in 1978 to identify, investigate, and
control the migration of hazardous contaminants at military and other DoD facilities.
Environmental Progress
By cleaning up the industrial waste basins and drum sites and providing an alternate water supply to
residents and workers at the base, the Air Force has reduced the risk of immediate threats at the
Dover Air Force Base site while further investigations leading to cleanup activities are being
conducted.
April 1991 34 DOVER AIR FORCE BASE
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DOVER f / EPA REGION 3
S CONGRESSIONAL DIST. 01
GAS LIGHT CO. ^ Kelcrtv
DELAWARE
EPA ID# DED980693550
Site Description
The 1-acre Dover Gas Light Co. site operated as a coal gasification plant from 1859 to 1948 and
produced gas for street lamps from coal. When the plant was closed in 1948, the structures,
except for a brick garage, were demolished. Much of the plant was removed, but sections of the
tanks and other process equipment containing coal oil, coal tar, coke, and possibly acid were
buried on site. In 1984, remains of this coal gasification plant were found buried on the site.
The site currently is used as a parking lot, with a museum immediately adjacent. Approximately
10,000 people are within 1 mile of the site and an estimated 454,000 people are served by public
and private wells within 3 miles of the site. Seven of Dover's 14 municipal supply wells are
located within 1 mile of the site. The closest supply well, 1,000 feet from the site, draws from
the Cheswold aquifer and is part of Dover's municipal water system. Also nearby are a cemetery
and an historic church.
Site Responsibility: This site is being addressed through NPL LISTING HIST°RY
Federal, State, and potentially
responsible parties' actions.
Proposed Dat£ 01/22/87
Final Date: 10/04/89
Threats and Contaminants
Specific contaminants detected in the groundwater and soil include volatile organic
compounds (VOCs), lead, and polycyclic aromatic hydrocarbons (PAHs) from former
site activities. Possible health threats include ingestion of or direct contact with the
contaminated groundwater or soil. Contaminated groundwater may threaten nearby
water supplies; however, a 1988 sampling of two wells closest to the site did not
show signs of contamination.
35 April 1991
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Cleanup Approach
This site is being addressed in a single long-term remedial phase focusing on contamination at the
entire site.
Response Action Status
Entire Site: The potentially responsible parties are conducting an investigation into the
groundwater contamination at the site. The investigation will define the contaminants and
will recommend alternatives for final groundwater cleanup. The investigation is planned
to be completed in 1992, after which the parties, under EPA monitoring, will begin cleanup of the
site using the selected cleanup technologies. Current efforts include determining whether wetlands
or the river have been contaminated, conducting groundwater studies, and implementing on-site
borings and conducting an archaeological study.
Environmental Progress
After listing the Dover Gas Light Co. site on the NPL, the EPA determined that site conditions
currently did not threaten nearby residents or the environment while the potentially responsible
parties are conducting investigations and cleanup activities at the site.
April 1991 36 DOVER GAS LIGHT CO.
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E I DU PONT DE < EPA REGION 3
l-.l. U\J r will I LSL. ^ CONGRESSIONAL DIST. 01
IMP MO! IRQ fl, Pn IMP X New Castle County
IMHIVIUUnO GL UU., IIMLr. U^\ Along the Christiana River in Newport
(NEWPORT PIGMENT
MI **-» «»ir^r-ii i Newport Pigments
PLANT I AND FILL )
DELAWARE
EPA ID# DED980555122
Site Description
The E.I. Du Pont de Nemours & Co., Inc. (Newport Pigment Plant Landfill) site is a pigment
manufacturing facility consisting of two industrial landfills: the 7-acre North Disposal Area and
the 15-acre South Disposal Area. From 1902 to 1929, the plant manufactured lithopone, a white
inorganic pigment. In 1929, Du Pont purchased the plant and continued to produce lithopone
along with other organic and inorganic pigments. As part of the plant operations, the waste was
disposed of in the landfills. Ciba-Geigy purchased the pigment plant in 1984, while Du Pont
retained a magnetic tape manufacturing facility. Approximately 21,000 people reside within a
3-mile radius of the site. Also within 3 miles of the site are three public water supply wells that
serve approximately 150,000 people. There are a number of private supply wells within 1/2 mile
of the site. Fifteen residential wells and the three public water supply wells are threatened by
groundwater contamination. The site is within a 100-year flood plain, with wetlands and the
Christiana River located nearby. The Christiana River is used for recreational purposes.
Site Responsibility: This site is being addressed through
Federal and potentially responsible
parties' actions.
NPL LISTING HISTORY
Proposed Date: 01/22/87
Final Date: 02/16/90
Threats and Contaminants
7\
Heavy metals and chlorinated solvents from past disposal practices have been detected in
the groundwater. Monitoring well information indicated contamination of the underlying
Columbia and Potomac aquifers. Heavy metals have been detected at the landfills,
underneath the Ciba-Geigy plant, and in wetland sediments and surface water. The
contaminated groundwater may migrate and eventually pose a health risk to owners of
nearby private wells. The groundwater contamination also poses a threat to the
Christiana River and the wetlands.
37 April 1991
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Cleanup Approach
This site is being addressed in a single long-term remedial phase focusing on cleanup of the entire
site.
Response Action Status
Entire Site: The parties potentially responsible for the site contamination started an
investigation in 1988 to determine the extent of the contamination and to identify
alternative cleanup technologies. The investigation is scheduled to be completed in 1992.
After completion of the studies, the parties, under EPA supervision, will begin cleanup of
contaminants at the site.
Site Facts: Du Pont entered into an Administrative Order on Consent with the EPA in 1988, under
which Du Pont agreed to perform a study to determine the nature and extent of the contamination
and to identify alternative cleanup technologies.
Environmental Progress
After adding this site to the NPL, the EPA performed a preliminary evaluation at the E.I. Du Pont de
Nemours & Co., Inc. (Newport Pigment Plant Landfill) site and determined that it currently did not
pose an immediate threat to public health and the environment while further investigations continue
and cleanup alternatives are being identified.
April 1991 38 E.I. DU PONT DE NEMOURS & CO., INC.
(NEWPORT PIGMENT PLANT LANDFILL)
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H ALBY (% EPA REGION 3
< CONGRESSIONAL DIST. 01
CHEMICAL CO.
DELAWARE
EPA ID# DED980830954
Site Description
The 14-acre Halby Chemical Co. site operated as a chemical manufacturing facility from 1948 to
1977. Wastewater from the production of chemicals at the plant was discharged into a 1 1/2-acrc
unlined lagoon and then discharged into a tidal marsh leading to the Lobdell Canal. Currently,
the lagoon receives intertidal flow through an interstate highway drainage ditch. During
preliminary investigations, drums from a storage area also were found to be leaking. Preliminary
sampling results indicated significant contamination of lagoon sediment in the vicinity of the
former process buildings. There also is significant soil contamination underlying the backfilled
portions of the waste lagoon. Approximately 1,800 people live within a mile of the site. Area
residents receive water from the Artesian Water Company, which draws water from several
uncontaminated wells. There is only one known residential well and one public well within 3
miles of the site.
Site Responsibility: This site is being addressed through NPL LISTING HISTORY
Federal actions.
Proposed Date: 09/18/85
Final Date: 06/01/86
Threats and Contaminants
The groundwater is contaminated with volatile organic compounds (VOCs) and
heavy metals including arsenic and zinc. Sampling of the lagoon sediments
revealed high levels of carbon disulfide, zinc, arsenic, and lead. The surface
water is contaminated with arsenic and heavy metals including lead, cadmium,
and mercury. Heavy metals including arsenic and zinc, and polycyclic aromatic
hydrocarbons (PAHs) were detected in the soil. Potential health threats include
accidental ingestion, inhalation, or direct contact with contamination in the
groundwater, surface water, lagoons, or soil.
39 April 1991
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Cleanup Approach
This site is being addressed in two long-term remedial phases focusing on cleanup of the soil;
and cleanup of the air, groundwater, and sediments.
Response Action Status
Soil: Based on the EPA's investigations, a remedy for the soil inside the process plant
area was proposed in 1991. The proposed remedy includes consolidation of all debris;
soil sampling; a treatability study related to soil stabilization; excavation, stabilization,
and backfilling of the top 6 inches of contaminated surface soil; placing an asphalt cap over the
stabilized soil; implementation of deed restrictions; and public education programs. Long-term
monitoring and site maintenance will ensure the effectiveness of the remedy. Final selection of
the remedy is expected in mid-1991. Technical design work is scheduled to begin in 1992.
Air, Groundwater, and Sediments: In 1991, the EPA is scheduled to begin an
investigation of the nature and extent of contamination in the air, groundwater, and
sediments in the outfall area and tidal marsh area. This study is scheduled for
conclusion in 1993.
Environmental Progress
After adding the Halby Chemical Co. site to the NPL, the EPA performed preliminary investigations
and determined that conditions at the site did not pose an immediate threat to public health or to its
surroundings while further investigations are underway.
April1991 40 HALBY CHEMICAL CO.
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HARX/FY Rt KNOTT i \ EPA REGION 3
n/-\nvti oc IVIMV-T i i ^ CONGRESSIONALDIST.01
DRUM, INC.
DELAWARE
EPA ID# DED980713093
New Castle County
About 5 miles from Kirkwood
Site Description
The Harvey & Knott Drum, Inc. site operated as an open dump and burning area between 1963 and
1969 on a portion of a 20-acre site. The facility accepted sanitary, municipal, and industrial wastes
believed to be sludges, paint pigments, and solvents. Wastes were emptied onto the ground surface
into excavated trenches or left in drums, some of which were buried on site. Several hundred drums
remain on site. A security fence, enclosing about 2 1/2 acres, was erected around the most visible
areas of contamination. The enclosed area includes drum stockpiles, waste piles, and a small pond.
Trailer homes and a residential development are located to the north of the property. Water supplies
for some of the nearby residences are obtained from a shallow water-table aquifer. There are
approximately 300 people living within 1 mile of the site. The site facility is set back several
hundred feet from the highway in an open field in a relatively undeveloped area and is surrounded
by woodlands. Wetlands are located to the south of the site.
Site Responsibility: This site is being addressed through
Federal, State, and potentially
responsible parties' actions.
NPL LISTING HISTORY
Proposed Date: 07/01/82
Final Date: 09/01/83
Threats and Contaminants
Specific contaminants detected in the groundwater include volatile organic compounds
(VOCs) such as ethyl benzene and toluene and heavy metals including arsenic, cadmium,
and lead. Heavy metals were detected in on-site sediments and surface water.
Contaminants detected in soils and sediments include VOCs, heavy metals, and
polychlorinated biphenyls (PCBs). Potential health threats exist through accidental
ingestion of, inhalation of, and direct contact with contaminated groundwater.
Trespassers and workers may be exposed to contaminants in on-site soil and waste
through accidental ingestion, direct contact, and inhalation at levels that pose health
concerns. Contaminated surface soils beyond the western property boundary pose similar
concerns for persons entering that area. Wetlands also may be threatened.
41 ApriM991
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Cleanup Approach
The site is being addressed in two stages: immediate actions and a long-term remedial phase
focusing on drum removal and groundwater pumping and treatment.
Response Action Status
Immediate Actions: The State supplied emergency drinking water to affected residents
in 1981. In 1982, the EPA completed immediate measures which included installing a
security fence, overpacking and staging 43 leaking drums, and conducting a sampling
survey. In addition, 17 monitoring wells were installed to identify the nature and extent of
groundwater contamination. In 1983 and 1984,46 drums were removed and disposed of off site, a
soil berm and a surface drainage ditch around a PCB-contaminated waste pile were constructed, 500
empty drums were crushed and staged, and 200 partially filled drums were staged.
Drum Removal and Groundwater Pumping and Treatment: Cleanup
technologies selected to address the first phase, contaminated drums, include: (1) the
removal of surface and subsurface drums; (2) extraction and on-site treatment of surface
water; (3) excavation of sediments, soil, and bulk wastes with off-site disposal at an approved
facility; (4) disposal of sludges, drums, and other debris at an off-site facility; (5) extraction and
treatment of groundwater using effluent to flush contaminants from on-site surface and subsurface
soils; and (6) preparation of the site for a flushing pipe network entailing grading, covering with
clean soil, and revegetation. Cleanup activities are presently underway. The removal of surface and
subsurface drums and the disposal of sludges have been accomplished. Currently under review, to
determine if cleanup is necessary, is the extraction and treatment of surface water, groundwater, and
flushing pipe network. The phase one excavation and removal of soil, sediments, and bulk wastes is
expected to be completed in 1992. The EPA currently is conducting an investigation of the second
phase, groundwater pumping and treatment. The second phase investigation will define the
contaminants of concern and will identify whether there is a need for groundwater cleanup. The
investigation is planned to be completed in 1991.
Site Facts: In 1977, a Consent Decree was entered into between EPA and a party potentially
responsible for the contamination, requiring the party to conduct an investigation into the nature and
extent of contamination at the site. In 1988, a Consent Decree was entered into between EPA and
another potentially responsible party. In 1988, the EPA filed suit against a potentially responsible
party to recover the incurred costs.
Environmental Progress
By providing an emergency drinking water supply to affected residents, installing a security fence
around the site, and removing all the surface and subsurface leaking drums, the EPA has
significantly reduced the potential for exposure to hazardous materials at the Harvey & Knott Drum,
Inc. site. Cleanup of the groundwater and further measures to remove contaminated drums, soils,
sediments, and surface water from the site currently are being addressed.
April 1991 42 HARVEY & KNOTT DRUM, INC.
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KENT COUNTY
LANDFILL
(HOUSTON)
DELAWARE
EPA ID# DED980705727
EPA REGION 3
CONGRESSIONAL DIST. 01
Kent County
About 2 miles north of Houston
Site Description
The 145-acre Kent County Landfill (Houston) site was operated by the County from 1969 to
1980. Among the wastes accepted were residential trash, pesticides, sludges from poultry
processing plants, oil sludges, hospital wastes, waste polymers, and solvents. The landfill holds
an estimated 2 million cubic yards of waste and fill materials. The wastes were deposited in
unlined trenches. In 1980, the County covered the landfill with 3 to 5 feet of sandy soil and
planted grass and other vegetation. In 1984, the EPA found contaminants in a monitoring well in
the water table aquifer underlying the site. The EPA also found contaminated leachate seeping
from the landfill. Approximately 684 people use private wells within 3 miles of the site. About
1,200 acres of cropland within 3 miles of the site are irrigated by well water, and surface water
near the site is used for recreational purposes.
Site Responsibility: This site is being addressed through a
combination of Federal, County, and
potentially responsible parties' actions.
NPL LISTING HISTORY
Proposed Date: 06/16/88
Final Date: 08/30/90
Threats and Contaminants
The groundwater is contaminated with volatile organic compounds (VOCs) including
benzene and vinyl chloride and heavy metals including chromium, arsenic, and
manganese from former disposal practices at the site. The soil in leachate seep
sediments is contaminated with heavy metals including iron, manganese, barium, and
cobalt. People who trespass on the unfenced site and who come into direct contact
with or accidentally ingest contaminated groundwater or leachate may be at risk.
Cleanup Approach
The site is being addressed in a single long-term remedial phase focusing on cleanup of the entire
site.
43
April 1991
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Response Action Status
Entire Site: The parties potentially responsible for the site contamination will
conduct a study to determine the nature and extent of contamination. This study,
which is expected to begin in 1991, will recommend alternatives for the final cleanup.
After completion of the study, the potentially responsible parties, under EPA supervision, will
perform cleanup activities to reduce groundwater and soil contamination to acceptable levels.
Environmental Progress
After adding this site to the NPL, the EPA performed a preliminary investigation and determined
that contamination at the Kent County Landfill (Houston) site currently does not pose an
immediate threat to the public or the environment while waiting for investigation and cleanup
activities to begin.
April 1991
44
KENT COUNTY LANDFILL (HOUSTON)
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I1VIP tor EPA REGION 3
., IIMU. PJ CONGRESSIONAL DIST. 01
(NEWPORT PLANT)
DELAWARE
EPA ID# DED980552244
Site Description
The 317-acre Koppers Co., Inc. (Newport Plant) site operated as a wood preserving plant from 1929
until 1971. During operations, Koppers loaded railroad ties and telephone poles into cylinders and
pressure-injected them with either creosote or a mixture of fuel oil and pentachlorophenol (POP). A
pond filled with water and used for fire protection and a sump where effluent from the treatment
process was collected were in the treatment area. In 1971, Koppers sold the site to Du Pont. As part
of the sales agreement, Koppers removed chemicals in the process tanks. Du Pont removed all
structures from the site; the site currently is vacant. In 1984, the EPA detected creosote compounds
in on-site soil and in nearby creek sediments. The Artesian Water Company draws drinking water
from three wells within 3 miles of the site and blends the water with other water to serve its 150,000
customers. The three wells tap the Lower Potomac Formation, hydraulically connected to the
overlying Columbia Formation, permitting water to move between them. Wetlands are found both
on and around the site.
Site Responsibility: This site is being addressed through
Federal actions.
NPL LISTING HISTORY
Proposed Date: 10/26/89
Final Date: 08/30/90
Threats and Contaminants
Soil and nearby creek and pond sediments are contaminated with polycyclic aromatic
hydrocarbons (PAHs) from the wood preserving treatment processes. Potential health
threats include accidental ingestion of and direct contact with contaminated soil and
sediments. Wetlands may also may be threatened.
45 April 1991
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Cleanup Approach
This site is being addressed in a single long-term remedial phase focusing on cleanup of the entire
site.
Response Action Status
Entire Site: The EPA is planning to conduct an investigation to determine the nature and
extent of contamination at the site. This investigation is scheduled to begin in 1991.
Alternative cleanup technologies will be selected, and cleanup activities will begin soon
thereafter.
Environmental Progress
The EPA assessed conditions at the Koppers Co., Inc. (Newport Plant) site and determined that no
intermediate actions were required to make the site safer while investigations are being planned.
April 1991
46
KOPPERS CO.. INC. (NEWPORT PLANT)
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MPR PORP 1 / EPA REGION 3
uvrnwwnr. |^ CONGRESSIONAL DIST. 01
(MILLSBORO PLA
DELAWARE
Sussex County
1/2 mile southeast of Millsboro
EPA ID# DED043958388 Fir.t Freedom Center
Site Description
NCR Corp. manufactured cash registers from 1967 to 1975 and electronic equipment from 1975
to 1980, at this 58-acre site 1/2 mile southeast of Millsboro. Between 1967 and 1974, the
company ran electroplating processes that produced a chromium-bearing waste. Workers treated
this waste on site. NCR subsequently excavated this material. Two of three concrete-lined
storage lagoons on site contained toxic materials that were later drained and removed. In 1981,
the First National Bank of Maryland bought the property, now known as First Freedom Center.
NCR assumed all environmental responsibilities in the deed of sale. The State required NCR to
monitor groundwater after the site was closed. Monitoring results showed that groundwater
under the property was contaminated with volatile organic compounds (VOCs) and metals. The
contaminated groundwater is entering Iron Branch Creek, which flows into a recreational stream
called Indian River. Riverview is located close to the site and is a community of about 30 small
houses that draw drinking water supplies from groundwater wells. About 4,700 people depend
on public and private wells within 3 miles of the site as a source of drinking water. The nearest
well is 10 feet away from the site, and the nearest people are 150 feet away. An estimated 1,000
people live within 1 mile; approximately 4,200 are within 3 miles of the site.
Site Responsibility: This site is being addressed through a
combination of Federal, State, and
potentially responsible parties' actions.
NPL LISTING HISTORY
Proposed Date: 04/01/85
Final Date: 07/01/87
Threats and Contaminants
The groundwater is contaminated with VOCs including trichloroethylene (TCE)
and with total and hexavalent chromium. A plume of solvent waste has reached
Iron Branch Creek, but no domestic supply wells are affected. People who come
into direct contact with or accidentally ingest contaminated groundwater or
surface water may be at risk.
47 April 1991
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Cleanup Approach
The site is being addressed in two stages: initial actions and a long-term remedial phase directed at
cleanup of the entire site.
Response Action Status
Initial Actions: NCR excavated chromium-bearing sludge from an unlined pit and
drained and removed toxic materials from two concrete-lined storage lagoons. NCR
continued to monitor groundwater after site closure, and installed 28 wells for that
purpose. In 1988, an air stripper and a recovery well were put into operation in an effort to prevent
off-site migration of contaminants.
Entire Site: Under State supervision, NCR is conducting an intensive study of
groundwater contamination at the site. This investigation, which will explore the nature
and extent of pollution and will recommend the best strategies for final cleanup, is
expected to be completed in late 1991.
Site Facts: A Consent Order for NCR to undertake initial response measures and a study to
determine the nature and extent of contamination and to identify alternatives for cleanup was signed
in 1988. The State ordered NCR to undertake an EPA-approved site closure in 1981.
Environmental Progress
The removal of contaminated sludge and the installation of monitoring wells to chart contaminant
levels, as well as the construction of an air stripper and recovery well, have reduced the potential for
exposure to hazardous materials at the NCR Corp. (Millsboro Plant) site while further cleanup
activities are being planned.
April 1991 48 NCR CORP. (MILLSBORO PLANT)
-------
NEW CASTLE SPILL (3 EPA REGION 3
IMt.VV OA-iO I L-l- oriUl.
-------
Cleanup Approach
The site is being addressed in a single long-term remedial phase focusing on cleanup of the entire
site.
Response Action Status
Entire Site: From 1977 to 1978, the NCBW&L, under the DNREC's instruction,
pumped the groundwater from the shallow aquifer into the nearby wetlands to prevent
migration of TRIS into aquifers beneath the site. In 1989, the EPA selected a remedy that
requires quarterly monitoring of the shallow aquifer groundwater for TRIS until the accepted safe
level is reached in an estimated four to five years; annual monitoring of the deeper groundwater
aquifer, surface water, and sediments of the wetland; establishing institutional controls; and
reviewing the effectiveness of the remedy in five years. Design activities are scheduled to begin in
1991 and include the completion of plans for continued monitoring of groundwater, surface water,
and sediments in the wetland. The State has established the institutional controls by restricting the
installation of wells within 1/2 mile of the site.
Site Facts: A Consent Decree was signed in 1990, in which the potentially responsible parties will
conduct the five-year review of the remedy. However, deadlines for the review will not be
established until the Consent Decree is recognized by the courts.
Environmental Progress
By providing an alternative municipal water source and by limiting the future use of the groundwater
until the cleanup levels have been reached, the potential for exposure to hazardous materials at the
New Castle Spill site has been reduced. Groundwater and surface water monitoring is presently
underway at the site to ensure continued environmental progress.
April 1991 50 NEW CASTLE SPILL
-------
NFW
ini-vv
OTCCI P| AMT
O I CCL. r L/nJM I
DELAWARE
EPA ID# DED980705255
EPA REG|ON 3
CONGRESSIONAL DIST. 01
New Castle County
Near the Delaware River in the
Other Names:
Deemer Steel Company
Site Description
For 80 years, Deemer Steel used the 3-acre New Castle Steel Plant landfill to dispose of its process
wastes. Until the plant closed in 1987, workers dumped foundry sands, slag, coke, iron oxide scale,
baghouse dust, and metal scrap into two disposal areas separated by a drainage channel that runs to
the Delaware River. Regulations in 1980 indicated that the baghouse dust was a hazardous waste
because of unacceptable levels of cadmium, chromium, and lead. The site was placed on the NPL in
1982 because of potential groundwater contamination. The EPA subsequently changed the
regulation, and the baghouse dust no longer was considered a hazardous waste. Although metals
associated with the site have entered soils, sediments, surface water, and groundwater, the EPA has
determined that contamination levels at the site are not threatening and do not necessitate cleanup
actions.
Site Responsibility:
This site was addressed through a
combination of Federal, State, and
potentially responsible parties' actions.
NPL LISTING HISTORY
Proposed Date: 12/01/82
Final Date: 09/01/83
Deleted Date: 03/17/89
Threats and Contaminants
The groundwater, sediments, soil, and surface water were contaminated with low levels
of heavy metals including arsenic, chromium, lead, cadmium, and nickel from the wastes
disposed of on site. However, contamination levels were low and did not pose threats to
nearby residents or the environment.
51
April 1991
-------
Cleanup Approach
This site was addressed in a long-term remedial phase focusing on cleanup of the entire site.
Response Action Status
Entire Site: After years of data collection and study, including an intensive investigation
undertaken by the Deemer Steel Company, both the EPA and the State have determined
that this site constitutes no significant threat to human health or the environment. The
selected remedy is "no action," indicating that no further actions are required to clean up the site.
Environmental Progress
Because the site studies have indicated that site contamination has attenuated and no longer poses a
risk to the public or the environment, the EPA, in conjunction with the State, deleted the New Castle
Steel Plant from the NPL in 1989.
April 1991
52
NEW CASTLE STEEL PLANT
-------
CCA I AND W EPA REGION 3
^-^i-**1*^ CONGRESSIONAL DIST. 01
DELAWARE
EPA ID#DED981 035520
New Castle County
Mount Pleasant
Site Description
Operations at the 2-acre Sealand Limited site began in 1971, when Adams Laboratory rented the
property from Conrail, Inc. to operate a rendering plant. In 1979, the owner reportedly cleaned up
the property after its tenant abandoned the plant. The property remained unused until it was rented
by the Sealand Limited and Oil Industry in 1982 to operate a waste oil recycling plant. The
operation accepted coal tar, gas tar, and ink oil wastes, allegedly for recycling, and stored them on
site in tanks and drums. When the tenants abandoned the facility in 1983, the site contained 22
storage tanks, a boiler house, mixing chambers, pressure vessels, several hundred 55-gallon drums
containing assorted creosote-related chemicals, and a 10,000-gallon wooden storage tank. A State
investigation in 1983 revealed that the wooden tank and numerous drums were leaking. Analyses of
the tanks, drums, and soil detected polycyclic aromatic hydrocarbons (PAHs), creosotes, solvents,
and other toxic organic compounds. A combined State and EPA study in 1984 showed contaminants
in an on-site monitoring well. Soils on the site are permeable and groundwater is shallow,
conditions that ease the movement of contaminants into groundwater. The area is primarily
agricultural and residential. Private wells within 3 miles of the site provide drinking water to an
estimated 1,000 people.
Site Responsibility: This site is being addressed through
Federal and potentially responsible
parties' actions.
NPL LISTING HISTORY
Proposed Date: 06/16/88
Final Date: 08/30/90
Threats and Contaminants
The soil is contaminated with PAHs, creosotes, solvents, and other toxic compounds
from the former recycling operation. Possible health threats include accidentally
ingesting or coming in direct contact with the contaminated materials at the site.
53 April 1991
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Cleanup Approach
The site is being addressed in two stages: emergency actions and a long-term remedial phase
focusing on cleanup of the entire site.
Response Action Status
Emergency Actions: In 1983, in response to the imminent threat to human health, the
EPA removed 240,800 gallons of coal tar, 320 drums, and 80 cubic yards of solid waste.
Workers transported the hazardous materials to an EPA-approved facility, cleaned the
storage tanks, and capped the site with a layer of clay and topsoil to keep rainwater and runoff from
spreading pollutants.
Entire Site: The parties potentially responsible for the site contamination are conducting
an intensive study of the nature and extent of site contamination, scheduled for completion
in 1991. Once the study has been completed, the EPA will select the final remedy for the
site.
Environmental Progress
By removing contaminated materials from the Sealand Limited site, the EPA has eliminated
immediate dangers to area residents and the environment while the potentially responsible parties,
under EPA monitoring, complete the site investigations and begin cleanup activities.
April 1991 54 SEALAND LIMITED
-------
STANDARD CHLORINE
OF DELAWARE, INC.
DELAWARE
EPAID#DED041212473
EPA REGION 3
CONGRESSIONAL DIST. 01
New Castle County
Delaware City
Site Description
The 46-acre Standard Chlorine of Delaware, Inc. site manufactures chlorinated benzenes and was
listed on the NPL due to a 1981 benzene spill from a railroad tanker car onto the property. An
additional spill occurred in 1986; 569,000 gallons of various volatile organic compounds (VOCs)
spilled after a 375,000-gallon tank of VOCs split open, collapsed, and damaged three nearby tanks of
VOCs, causing the latter tanks to partially spill. About 152,000 people draw groundwater from
public and private wells within a 3-mile radius of the site. Approximately 30 people reside within a
mile of the site.
Site Responsibility: This site is being addressed through a
combination of Federal, State, and
potentially responsible parties' actions.
NPL LISTING HISTORY
Proposed Date: 09/01/85
Final Date: 07/01/87
Threats and Contaminants
Chlorobenzenes from spilled material have been found in the groundwater, soil, and
surface water. People may be exposed to the chemicals by direct contact with
contaminated soil or accidentally ingesting contaminated soil or water. Wetlands near
the site also may be threatened by contamination emanating from the spill areas.
Cleanup Approach
This site is being addressed in two stages: emergency actions and a long-term remedial phase
focusing on contamination at the entire site.
55
April 1991
-------
Response Action Status
Emergency Actions: The Delaware Department of Natural Resources and
Environmental Control (DNREC) and Standard Chlorine Co. took the following
emergency actions in response to the January 1986 spill: (1) excavated a drainage ditch;
(2) built a filter fence along the mouth of the wetland coves; (3) performed pre-excavation sampling
and constructed an earthen dike to isolate the upper portions of the wetland from contaminants; (4)
excavated contaminated sediments upstream of the dike; and (5) built a basin to trap contaminated
sediments in tidal areas of the cove (between the dike and the filter fence).
Entire Site: Under State order, the parties potentially responsible for the site
contamination are conducting an intensive study of the effect the spill has had on local
groundwater quality, soil, and wetland contamination. The investigation will explore the nature and
extent of the contamination and will identify the best strategies for cleanup. The study is scheduled
for completion in 1993.
Environmental Progress
Emergency actions undertaken by the DNREC and Standard Chlorine Co. have reduced
contamination possibilities at the site. After a study is completed by the potentially responsible
parties, final cleanup actions will begin at the Standard Chlorine of Delaware, Inc. site.
April 1991 56 STANDARD CHLORINE
OF DELAWARE. INC.
-------
SUSSEX COUNTY
LANDFILL NO. 5
DELAWARE
EPA ID# DED980494637
Site Description
EPA REGION 3
CONGRESSIONAL DIST. 01
Sussex County
Laurel
The inactive 37 1/2-acre Sussex County Landfill No. 5 operated from 1970 until 1979. It
accepted municipal wastes and, according to a 1978 Congressional report, an unknown quantity
of various volatile organic compounds (VOCs). Wastes were deposited in the ground below the
water table, threatening groundwater. In 1986, the EPA detected several organic chemicals and
solvents in five on-site monitoring wells. The landfill overlies the Columbia Formation, which is
connected to and recharges the Manokin Aquifer. Together, the two provide drinking water to
people within 3 miles of the site. A private well is located 1,000 feet from the site. Public and
private wells within 3 miles of the site provide drinking water to an estimated 5,700 people and
irrigate 5,100 acres of cropland.
Site Responsibility:
This site is being addressed through a
combination of Federal, State, and
County actions.
NPL LISTING HISTORY
Proposed Date: 06/16/88
Final Date: 10/04/89
Threats and Contaminants
Five groundwater monitoring wells showed contamination from VOCs, including
benzene and vinyl chloride, from former disposal practices. Possible health
threats include drinking or coming in direct contact with the contaminated
groundwater. Bioaccumulation of contaminants in locally raised livestock and
crops is a threat if contaminated groundwater is used for watering or irrigation.
Cleanup Approach
This site is being addressed in a single long-term remedial phase focusing on cleanup of the
entire site.
57
April 1991
-------
Response Action Status
Entire Site: The landfill was closed by the Delaware Department of Natural
Resources and Environmental Control (DNREC) in 1979. The DNREC installed
monitoring wells on the site as a part of the closure plan. In 1984, the DNREC
conducted a preliminary assessment, which indicated that a leachate plume extended 400 to 500
feet downgradient of the site. In 1984, the EPA inspected the site and detected elevated levels of
VOCs in the groundwater. Several more wells have been installed in the vicinity of the landfill
and are monitored on a regular basis by Sussex County as part of the requirements of an
agreement between the County and DNREC. In addition, some domestic wells are monitored;
low levels of VOCs contamination have been found in one well just north of the site. An
intensive investigation of the site began in 1991. The County will investigate the nature and
extent of groundwater contamination and will recommend cleanup strategies for the site. The
study is expected to be completed in 1993.
Site Facts: The County and the DNREC have entered into an agreement to establish a
groundwater management program near the landfill. The County will monitor on-site wells and
adjacent domestic wells regularly. In March 1991, an Administrative Order for a site
investigation was signed by Sussex County and the EPA.
Environmental Progress
The EPA evaluated the Sussex County Landfill No. 5 and determined that the site does not
currently pose an immediate threat to nearby residents. By closing the landfill, the State has
eliminated the possibility of further contamination at the site while investigations and cleanup
activities are pursued.
April 1991 58 SUSSEX COUNTY LANDFILL NO. 5
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TYBOUTS CORNER m CONGRESSIONAL DIST.01
New Castle County
10 miles south of Wilmington
DELAWARE
EPA ID# DED000606079
Site Description
Tybouts Corner Landfill was constructed in a sand and gravel pit located in northern Delaware,
10 miles south of Wilmington and 4 miles west of the Delaware River. The main landfill area is
about 47 acres and is located near the confluence of Pigeon Run Creek and Red Lion Creek. The
fill ranges from 5 to 40 feet thick. Between 1968 and 1971, this privately owned landfill
accepted both municipal and industrial wastes, including volatile organic compounds (VOCs)
and various other organic and inorganic chemicals. Tybout's Corner was built without a clay
liner or other impervious material below the fill, and no clay cap was placed on top of the fill
after it was abandoned. EPA studies have revealed that two shallow aquifers beneath the site are
contaminated. About 42 homes and facilities surround the entire landfill property and most of
these have wells that draw from the aquifers contaminated by the site. Some of the residences
are less than 100 feet from the landfill. In addition, the landfill is located in an area of extensive
groundwater development, both for municipal supplies and large industrial facilities. The
possibility for contaminating the upper hydrologic zone of the Potomac Formation, an important
regional aquifer, exists.
Site Responsibility: This site is being addressed through NPL LISTIIVIG HISTORY
Federal and potentially responsible
parties' actions.
Proposed Date: 10/01/81
Final Date: 09/01/83
Threats and Contaminants
Local drinking water wells and soils are contaminated with VOCs and other
organic compounds from former disposal practices. Surface water is
contaminated with hazardous organic and inorganic substances. Ingesting or
coming into direct contact with contaminated water or soil may threaten the health
of people in the area.
59 April 1991
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Cleanup Approach
This site is being addressed in two stages: immediate actions and a long-term remedial phase
divided into two segments, source control and groundwater cleanup.
Response Action Status
Immediate Actions: The EPA installed a fence in 1982. Between 1984 and 1986,
the EPA extended the public water lines to provide service to all 42 residences and
facilities surrounding the landfill. The EPA repaired and reconstructed the security
fence around the site and posted warning signs in 1987.
Source Control and Groundwater Cleanup: The selected remedies chosen for
this site in 1986 organized the work into two phases. Phase 1: Source Control
includes excavating all municipal and industrial wastes, as well as contaminated
subsoils in the west fill and consolidation with the main fill; capping the consolidated main fill
area with a multi-layered cap to prevent rainwater from washing away contaminants; installing a
subsurface drain or trench system; implementing a health and safety plan; and establishing a
monitoring program. Phase 2: Groundwater Cleanup will consist of pumping and treating, or
otherwise disposing of, the area of contaminated groundwater off site in the upper hydrologic
zone of the Potomac Formation. If disposal is called for, it will occur either on site or off site at
a local sewage treatment plant. Restrictions to prevent use of contaminated groundwater will be
applied. The EPA began designing the remedy in 1988, and the potentially responsible parties
took over responsibility for the design in 1989. Cleanup activities are scheduled to begin in
1992, upon completion of these technical specifications.
Environmental Progress
With the construction of a fence around the site to limit access and the provision of a safe
drinking water source to affected residents and businesses, the EPA has made the Tybouts
Corner Landfill site safer while it awaits further cleanup activities.
April 1991 60 TYBOUTS CORNER LANDFILL
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Smyrna
TYLFR <: EPA REGION 3
1 l-c-ri | CONGRESSIONAL DIST. 01
REFRIGERATION \ v
PIT
DELAWARE
EPA ID# DED980705545
Site Description
From 1952 to 1969, Tyler Refrigeration, located on a 3-acre parcel of land, used solvents to
degrease and clean refrigeration equipment, and dumped the spent solvents, paint room wastes,
and sludges into two unlined disposal pits. In the 1970s, Clark Equipment Company excavated
the pit to a depth of 20 feet, filled it in, capped it with 6 inches of topsoil and clay, and planted
vegetation. The site is now occupied by Metal Masters, an active manufacturer of commercial
kitchen equipment. Public access is unrestricted, but most of the old pit's surface area has been
paved. In 1982, the EPA detected elevated levels of three solvents in the soils. Since 1977,
trichloroethylene (TCE) and trichloroethane have been detected in Smyrna's municipal wells.
The State believes that the Tyler pit is a likely contributor to this pollution, although there may
be other sources, since TCE has not been found in on-site soils or groundwater. About 6,700
people within 3 miles of the site get their drinking water from wells, both municipal and private.
Approximately 4,700 people rely on the public water supplies; 60 homes stand within 1/4 mile of
the site, with the closest being within 300 feet. Several private wells are reported in the vicinity
of the site.
Site Responsibility: This site is being addressed through
Federal and potentially responsible
parties' actions.
NPL LISTING HISTORY
Proposed Date: 06/01/86
Final Date: 02/21/90
Threats and Contaminants
The on-site groundwater is contaminated with volatile organic compounds (VOCs)
including trichloroethane from former process wastes. On-site monitoring wells also
have detected elevated levels of chromium in groundwater samples. The soil contains
elevated levels of VOCs, including toluene, dichloroethane, and trichloroethane.
Accidental ingestion of or direct contact with contaminated soil or groundwater from
the existing private wells may pose a health threat.
61 April!991
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Cleanup Approach
This site is being addressed in two stages: an immediate action and a long-term remedial phase
focusing on groundwater cleanup at the site.
Response Action Status
Immediate Action: To remove VOC contamination in the municipal wells, the town
improved the efficiency of its air-stripping process and added an activated carbon filtration
unit to its water treatment system. The treatment system continues to operate.
Groundwater: The parties potentially responsible for the site contamination began an
intensive study of the groundwater contamination at this site in 1991. This investigation
will reveal the nature and extent of the pollution and pinpoint the best cleanup strategies.
It is scheduled for completion in 1993; once completed, the EPA will select the final remedies for
cleanup of the groundwater and other contaminated areas at the Tyler Refrigeration Pit site.
Site Facts: A Consent Order was signed by Clark Equipment Company and EPA in 1991, under
which the company agreed to perform the investigation of site contamination.
Environmental Progress
By improving the air-stripping process and adding an activated carbon filtration unit to its water
treatment system, the town of Smyrna has eliminated VOC contamination from municipal wells,
making the public water supply safe while investigations are conducted at the Tyler
Refrigeration Pit site.
April 1991 62 TYLER REFRIGERATION PIT
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WILDCAT LANDFILI7 EPA REGION 3
VVIL-L^OAAI L.^UML^I IL-L/ CONGRESSIONAL DIST. 01
DELAWARE X Kent County
t"-t-J^W₯rtltl" \ 2 1/2 miles south of Dover,
EPA ID# DED980704951 V'CN adjacent to the St. Jones River
Site Description
From 1962 until 1973, a landfill operated on 44 acres of the 84-acre Wildcat Landfill site,
situated next to the St. Jones River in Dover, 1/2 mile west of the Dover Air Force Base (AFB)
NPL site. The privately owned landfill accepted municipal and industrial waste until it was
closed under a State order for numerous violations of a State permit. Operators dumped wastes
into wetlands and frequently left them uncovered. Groundwater is contaminated with heavy
metals, organics, and low levels of polychlorinated biphenyls (PCBs). Open and empty metal
drums, tires, solid latex, and municipal trash were scattered over the surface of the site. A 3-acre
pond, which collects surface drainage from the western half of the landfill, lies immediately to
the west of the landfill. Monitoring of drinking water wells in 1987 showed no contamination,
but contaminant levels in groundwater underneath and downgradient of the site are at levels of
public health concern. The St. Jones River, which borders the site, is used for recreational
fishing and boating. Two trailer parks, the Dover AFB housing complex, and 12 residences are
located within 1/2 mile of the site. Local residents rely on groundwater for drinking water
supplies and are served by public or private wells. There are 24 active wells within 1/2 mile and
16 within 1,000 feet of the site.
Site Responsibility: This site is being addressed through NPL LISTING HISTORY
Federal actions.
Threats and Contaminants
Proposed Date: 12/01/82
Final Date: 09/01/83
The groundwater is contaminated with chlordane, methylene chloride, and xylenes.
On-site surface water, leachate, soils, and sediments contain PCBs and chlordane, a
pesticide. Accidentally ingesting contaminated groundwater, surface water, soil,
sediments, or contaminated aquatic organisms or coming into direct contact with
contaminated groundwater, surface water, soil, sediments, and air may threaten the
health of people at or near the site. The State has issued a health advisory on fish
caught from the St. Jones River. The St. Jones marshlands are threatened, and lead
has been detected in snapping turtles on the site.
63 April 1991
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Cleanup Approach
The site is being addressed in two long-term remedial phases focusing on source control and pond
cleanup.
Response Action Status
Source Control: Cleanup activities for this site have been separated into two phases.
The first deals with the landfill itself, and the second addresses the 3-acre pond at the
northwestern corner of the landfill. The remedy selected for landfill cleanup features: (1)
restricting development of the site and preventing installation of drinking water wells on or near the
site; (2) grading, covering, and seeding on-site areas where direct risks of contact with contaminants
have been identified; (3) removing and disposing of drums; (4) replacing two domestic wells
adjacent to the site; and (5) monitoring groundwater. The cleanup work currently is underway, with
completion scheduled for 1993.
Pond Cleanup: The remedy for the 3-acre pond that drains the western half of the
landfill features filling in the existing pond and building a new shallow pond southeast of
the landfill. The technical specifications for pond cleanup were completed in early 1991,
and the cleanup activities are scheduled to begin later in 1991.
Environmental Progress
Removal of site contaminants, restricting the use of groundwater in the area, and the replacement of
contaminated wells are underway and are reducing the threat of exposure to hazardous materials
from the Wildcat Landfill site.
April 1991 64 WILDCAT LANDFILL
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APPENDIX A
Glossary:
Terms Used
in the
Fact Sheets
65
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GLOSSARY
This glossary defines terms used
throughout the NPL Volumes. The
terms and abbreviations contained in
this glossary apply specifically to work
performed under the Superfund program in
the context of hazardous waste management.
These terms may have other meanings when
used in a different context.
Terms Used
in the NPL
Book
Acids: Substances, characterized by low pH
(less than 7.0), that are used in chemical
manufacturing. Acids in high concentration
can be very corrosive and react with many
inorganic and organic substances. These
reactions possibly may create toxic com-
pounds or release heavy metal contaminants
that remain in the environment long after the
acid is neutralized.
Administrative Order On Consent: A legal
and enforceable agreement between the EPA
and the parties potentially responsible for site
contamination. Under the terms of the Order,
the potentially responsible parties (PRPs)
agree to perform or pay for site studies or
cleanups. It also describes the oversight rules,
responsibilities, and enforcement options that
the government may exercise in the event of
non-compliance by potentially responsible
parties. This Order is signed by PRPs and the
government; it does not require approval by a
judge.
Administrative Order [Unilateral]: A
legally binding document issued by the EPA,
directing the parties potentially responsible to
perform site cleanups or studies (generally,
the EPA does not issue Unilateral Orders for
site studies).
Aeration: A process that promotes break-
down of contaminants in soil or water by
exposing them to air.
Agency for Toxic Substances and Disease
Registry (ATSDR): The Federal agency
within the U.S. Public Health Service charged
with carrying out the health-related responsi-
bilities of CERCLA.
Air Stripping: A process whereby volatile
organic chemicals (VOCs) are removed from
contaminated material by forcing a stream of
air through it in a pressurized vessel. The
contaminants are evaporated into the air
stream. The air may be further treated before
it is released into the atmosphere.
Ambient Air: Any unconfined part of the
atmosphere. Refers to the air that may be
inhaled by workers or residents in the vicinity
of contaminated air sources.
Aquifer: An underground layer of rock,
sand, or gravel capable of storing water
within cracks and pore spaces, or between
grains. When water contained within an
aquifer is of sufficient quantity and quality, it
can be tapped and used for drinking or other
purposes. The water contained in the aquifer
is called groundwater. A sole source aquifer
supplies 50% or more of the drinking water of
an area.
Artesian (Well): A well made by drilling
into the earth until water is reached, which,
from internal pressure, flows up like a foun-
tain.
67
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GLOSSARY.
Attenuation: The naturally occurring pro-
cess by which a compound is reduced in
concentration over time through adsorption,
degradation, dilution, and/or transformation.
Background Level: The amount of a sub-
stance typically found in the air, water, or soil
from natural, as opposed to human, sources.
Baghouse Dust: Dust accumulated in remov-
ing particulates from the air by passing it
through cloth bags in an enclosure.
Bases: Substances characterized by high pH
(greater than 7.0), which tend to be corrosive
in chemical reactions. When bases are mixed
with acids, they neutralize each other, form-
ing salts.
Berm: A ledge, wall, or a mound of earth
used to prevent the migration of contami-
nants.
Bioaccumulate: The process by which some
contaminants or toxic chemicals gradually
collect and increase in concentration in living
tissue, such as in plants, fish, or people, as
they breathe contaminated air, drink contami-
nated water, or eat contaminated food.
Biological Treatment: The use of bacteria or
other microbial organisms to break down
toxic organic materials into carbon dioxide
and water.
Bioremediation: A cleanup process using
naturally occurring or specially cultivated
microorganisms to digest contaminants and
break them down into non-hazardous compo-
nents.
Bog: A type of wetland that is covered with
peat moss deposits. Bogs depend primarily
on moisture from the air for their water
source, are usually acidic, and are rich in plant
residue [see Wetland].
Boom: A floating device used to contain oil
floating on a body of water or to restrict the
potential overflow of waste liquids from
containment structures.
Borehole: A hole that is drilled into the
ground and used to sample soil or ground-
water.
Borrow Pit: An excavated area where soil,
sand, or gravel has been dug up for use
elsewhere.
Cap: A layer of material, such as clay or a
synthetic material, used to prevent rainwater
from penetrating and spreading contaminated
materials. The surface of the cap generally is
mounded or sloped so water will drain off.
Carbon Adsorption: A treatment system in
which contaminants are removed from
groundwater and surface water by forcing
water through tanks containing activated
carbon, a specially treated material that
attracts and holds or retains contaminants.
Carbon Disulfide: A degreasing agent
formerly used extensively for parts washing.
This compound has both inorganic and or-
ganic properties, which increase cleaning
efficiency. However, these properties also
cause chemical reactions that increase the
hazard to human health and the environment
Carbon Treatment: [see Carbon Adsorp-
tion].
Cell: In solid waste disposal, one of a series
of holes in a landfill where waste is dumped,
compacted, and covered with layers of dirt.
CERCLA: [see Comprehensive Environ-
mental Response, Compensation, and Liabil-
ity Act].
Characterization: The sampling, monitor-
ing, and analysis of a site to determine the
68
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GLOSSARY
extent and nature of toxic releases. Character-
ization provides the basis for acquiring the
necessary technical information to develop,
screen, analyze, and select appropriate
cleanup techniques.
Chemical Fixation: The use of chemicals to
bind contaminants, thereby reducing the
potential for leaching or other movement.
Chromated Copper Arsenate: An insecti-
cide/herbicide formed from salts of three toxic
metals: copper, chromium, and arsenic. This
salt is used extensively as a wood preservative
in pressure-treating operations. It is highly
toxic and water-soluble, making it a relatively
mobile contaminant in the environment.
Cleanup: Actions taken to eliminate a
release or threat of release of a hazardous
substance. The term "cleanup" sometimes is
used interchangeably with the terms remedial
action, removal action, response action, or
corrective action.
Closure: The process by which a landfill
stops accepting wastes and is shut down,
under Federal guidelines that ensure the
protection of the public and the environment.
Comment Period: A specific interval during
which the public can review and comment on
various documents and EPA actions related to
site cleanup. For example, a comment period
is provided when the EPA proposes to add
sites to the NPL. There is minimum 3-week
comment period for community members to
review and comment on the remedy proposed
to clean up a site.
Community Relations: The EPA effort to
establish and maintain two-way communica-
tion with the public. Goals of community
relations programs include creating an under-
standing of EPA programs and related ac-
tions, assuring public input into decision-
making processes related to affected commu-
nities, and making certain that the Agency is
aware of, and responsive to, public concerns.
Specific community relations activities are
required in relation to Superfund cleanup
actions [see Comment Period].
Comprehensive Environmental Response,
Compensation, and Liability Act
(CERCLA): Congress enacted the
CERCLA, known as Superfund, in 1980 to
respond directly to hazardous waste problems
that may pose a threat to the public health and
the environment. The EPA administers the
Superfund program.
Confluence: The place where two bodies of
water, such as streams or rivers, come to-
gether.
Consent Decree: A legal document, ap-
proved and issued by a judge, formalizing an
agreement between the EPA and the parties
potentially responsible for site contamination.
The decree describes cleanup actions that the
potentially responsible parties are required to
perform and/or the costs incurred by the
government that the parties will reimburse, as
well as the roles, responsibilities, and enforce-
ment options that the government may exer-
cise in the event of non-compliance by poten-
tially responsible parties. If a settlement
between the EPA and a potentially respon-
sible party includes cleanup actions, it must
be in the form of a Consent Decree. A Con-
sent Decree is subject to a public comment
period.
Consent Order: [see Administrative Order
on Consent].
Containment: The process of enclosing or
containing hazardous substances in a struc-
ture, typically in a pond or a lagoon, to pre-
vent the migration of contaminants into the
environment.
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GLOSSARY.
Contaminant: Any physical, chemical,
biological, or radiological material or sub-
stance whose quantity, location, or nature
produces undesirable health or environmental
effects.
Contingency Plan: A document setting out
an organized, planned, and coordinated course
of action to be followed in case of a fire,
explosion, or other accident that releases toxic
chemicals, hazardous wastes, or radioactive
materials into the environment.
Cooperative Agreement: A contract be-
tween the EPA and the States, wherein a State
agrees to manage or monitor certain site
cleanup responsibilities and other activities on
a cost-sharing basis.
Cost Recovery: A legal process by which
potentially responsible parties can be required
to pay back the Superfund program for money
it spends on any cleanup actions [see Poten-
tially Responsible Parties].
Cover: Vegetation or other material placed
over a landfill or other waste material. It can
be designed to reduce movement of water into
the waste and to prevent erosion that could
cause the movement of contaminants.
Creosotes: Chemicals used in wood preserv-
ing operations and produced by distillation of
tar, including polycyclic aromatic hydrocar-
bons and polynuclear aromatic hydrocarbons
[seePAHsandPNAs]. Contaminating
sediments, soils, and surface water, creosotes
may cause skin ulcerations and cancer
through prolonged exposure.
Culvert: A pipe used for drainage under a
road, railroad track, path, or through an
embankment.
Decommission: To revoke a license to
operate and take out of service.
Degradation: The process by which a
chemical is reduced to a less complex form.
Degrease: To remove grease from wastes,
soils, or chemicals, usually using solvents.
De minimis: This legal phrase pertains to
settlements with parties who contributed
small amounts of hazardous waste to a site.
This process allows the EPA to settle with
small, or de minimis contributors, as a single
group rather than as individuals, saving time,
money, and effort.
Dewater: To remove water from wastes,
soils, or chemicals.
Dike: A low wall that can act as a barrier to
prevent a spill from spreading.
Disposal: Final placement or destruction of
toxic, radioactive, or other wastes; surplus or
banned pesticides or other chemicals; polluted
soils; and drums containing hazardous materi-
als. Disposal may be accomplished through
the use of approved secure landfills, surface
impoundments, land farming, deep well
injection, or incineration.
Downgradient: A downward hydrologic
slope that causes groundwater to move toward
lower elevations. Therefore, wells downgra-
dient of a contaminated groundwater source
are prone to receiving pollutants.
Effluent: Wastewater, treated or untreated,
that flows out of a treatment plant, sewer, or
industrial outfall. Generally refers to wastes
discharged into surface waters.
Emission: Pollution discharged into the
atmosphere from smokestacks, other vents,
and surface areas of commercial or industrial
facilities.
Emulsifiers: Substances that help in mixing
materials that do not normally mix; e.g., oil
and water.
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GLOSSARY
Endangerment Assessment: A study con-
ducted to determine the risks posed to public
health or the environment by contamination at
NPL sites. The EPA or the State conducts the
study when a legal action is to be taken to
direct the potentially responsible parties to
clean up a site or pay for the cleanup. An
endangerment assessment supplements an
investigation of the site hazards.
Enforcement: EPA, State, or local legal
actions taken against parties to facilitate
settlements; to compel compliance with laws,
rules, regulations, or agreements; and/or to
obtain penalties or criminal sanctions for
violations. Enforcement procedures may
vary, depending on the specific requirements
of different environmental laws and related
regulatory requirements. Under CERCLA,
for example, the EPA will seek to require
potentially responsible parties to clean up a
Superfund site or pay for the cleanup [see
Cost Recovery].
Erosion: The wearing away of land surface
by wind or water. Erosion occurs naturally
from weather or surface runoff, but can be
intensified by such land-related practices as
farming, residential or industrial develop-
ment, road building, or timber-cutting. Ero-
sion may spread surface contamination to off-
site locations.
Estuary (estuarine): Areas where fresh
water from rivers and salt water from
nearshore ocean waters are mixed. These
areas may include bays, mouths of rivers, salt
marshes, and lagoons. These water ecosys-
tems shelter and feed marine life, birds, and
wildlife.
Evaporation Ponds: Areas where sewage
sludge or other watery wastes are dumped and
allowed to dry out.
Feasibility Study: The analysis of the
potential cleanup alternatives for a site. The
feasibility study usually starts as soon as the
remedial investigation is underway; together,
they are commonly referred to as the RI/FS
[see Remedial Investigation].
Filtration: A treatment process for removing
solid (particulate) matter from water by
passing the water through sand, activated
carbon, or a man-made filter. The process is
often used to remove particles that contain
contaminants.
Flood Plain: An area along a river, formed
from sediment deposited by floods. Flood
plains periodically are innundated by natural
floods, which can spread contamination.
Flue Gas: The air that is emitted from a
chimney after combustion in the burner
occurs. The gas can include nitrogen oxides,
carbon oxides, water vapor, sulfur oxides,
particles, and many chemical pollutants.
Fly Ash: Non-combustible residue that
results from the combustion of flue gases. It
can include nitrogen oxides, carbon oxides,
water vapor, sulfur oxides, as well as many
other chemical pollutants.
French Drain System: A crushed rock drain
system constructed of perforated pipes, which
is used to drain and disperse wastewater.
Gasification (coal): The conversion of soft
coal into gas for use as a fuel.
Generator: A facility that emits pollutants
into the air or releases hazardous wastes into
water or soil.
Good Faith Offer: A voluntary offer, gener-
ally in response to a Special Notice letter,
made by a potentially responsible party,
consisting of a written proposal demonstrating
a potentially responsible party's qualifications
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GLOSSARY.
and willingness to perform a site study or
cleanup.
Groundwater: Underground water that fills
pores in soils or openings in rocks to the point
of saturation. In aquifers, groundwater occurs
in sufficient quantities for use as drinking and
irrigation water and other purposes.
Groundwater Quality Assessment: The
process of analyzing the chemical characteris-
tics of groundwater to determine whether any
hazardous materials exist.
Halogens: Reactive non-metals, such as
chlorine and bromine. Halogens are very
good oxidizing agents and, therefore, have
many industrial uses. They are rarely found
by themselves; however, many chemicals
such as polychlorinated biphenyls (PCBs),
some volatile organic compounds (VOCs),
and dioxin are reactive because of the pres-
ence of halogens.
Hazard Ranking System (HRS): The
principal screening tool used by the EPA to
evaluate relative risks to public health and the
environment associated with abandoned or
uncontrolled hazardous waste sites. The HRS
calculates a score based on the potential of
hazardous substances spreading from the site
through the air, surface water, or groundwater
and on other factors such as nearby popula-
tion. The HRS score is the primary factor in
deciding if the site should be on the NPL.
Hazardous Waste: By-products of society
that can pose a substantial present or potential
hazard to human health and the environment
when improperly managed. It possesses at
least one of four characteristics (ignitability,
corrosivity, reactivity, or toxicity), or appears
on special EPA lists.
Hot Spot: An area or vicinity of a site con-
taining exceptionally high levels of contami-
nation.
Hydrogeology: The geology of groundwater,
with particular emphasis on the chemistry and
movement of water.
Impoundment: A body of water or sludge
confined by a dam, dike, floodgate, or other
barrier.
Incineration: A group of treatment technolo-
gies involving destruction of waste by con-
trolled burning at high temperatures, e.g.,
burning sludge to reduce the remaining
residues to a non-burnable ash that can be
disposed of safely on land, in some waters, or
in underground locations.
Infiltration: The movement of water or other
liquid down through soil from precipitation
(rain or snow) or from application of waste-
water to the land surface.
Influent: Water, wastewater, or other liquid
flowing into a reservoir, basin, or treatment
plant.
Injection Well: A well into which waste
fluids are placed, under pressure, for purposes
of disposal.
Inorganic Chemicals: Chemical substances
of mineral origin, not of basic carbon struc-
ture.
Installation Restoration Program: The
specially funded program established in 1978
under which the Department of Defense has
been identifying and evaluating its hazardous
waste sites and controlling the migration of
hazardous contaminants from those sites.
Intake: The source from where a water
supply is drawn, such as from a river or water
body.
Interagency Agreement: A written agree-
ment between the EPA and a Federal agency
that has the lead for site cleanup activities,
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GLOSSARY
setting forth the roles and responsibilities of
the agencies for performing and overseeing
the activities. States often are parties to
interagency agreements.
Interim (Permit) Status: Conditions under
which hazardous waste treatment, storage,
and disposal facilities, that were operating
when regulations under the RCRA became
final in 1980, are temporarily allowed by the
EPA to continue to operate while awaiting
denial or issuance of a permanent permit. The
facility must comply with certain regulations
to maintain interim status.
Lagoon: A shallow pond or liquid waste
containment structure. Lagoons typically are
used for the storage of wastewaters, sludges,
liquid wastes, or spent nuclear fuel.
Landfarm: To apply waste to land and/or
incorporate waste into the surface soil, such
as fertilizer or soil conditioner. This practice
commonly is used for disposal of composted
wastes and sludges.
Landfill: A disposal facility where waste is
placed in or on land. Sanitary landfills are
disposal sites for non-hazardous solid wastes.
The waste is spread in layers, compacted to
the smallest practical volume, and covered
with soil at the end of each operating day.
Secure chemical landfills are disposal sites for
hazardous waste. They are designed to
minimize the chance of release of hazardous
substances into the environment [see Re-
source Conservation and Recovery Act].
Leachate [n]: The liquid that trickles
through or drains from waste, carrying soluble
components from the waste. Leach, Leach-
ing [v.t.]: The process by which soluble
chemical components are dissolved and
carried through soil by water or some other
percolating liquid.
Leachate Collection System: A system that
gathers liquid that has leaked into a landfill or
other waste disposal area and pumps it to the
surface for treatment.
Liner: A relatively impermeable barrier
designed to prevent leachate (waste residue)
from leaking from a landfill. Liner materials
include plastic and dense clay.
Long-term Remedial Phase: Distinct, often
incremental, steps that are taken to solve site
pollution problems. Depending on the com-
plexity, site cleanup activities can be sepa-
rated into several of these phases.
Marsh: A type of wetland that does not
contain peat moss deposits and is dominated
by vegetation. Marshes may be either fresh or
saltwater and tidal or non-tidal [see Wetland].
Migration: The movement of oil, gas,
contaminants, water, or other liquids through
porous and permeable soils or rock.
Mill Tailings: [See Mine Tailings].
Mine Tailings: A fine, sandy residue left
from mining operations. Tailings often
contain high concentrations of lead, uranium,
and arsenic or other heavy metals.
Mitigation: Actions taken to improve site
conditions by limiting, reducing, or control-
ling toxicity and contamination sources.
Modeling: A technique using a mathematical
or physical representation of a system or
theory that tests the effects that changes on
system components have on the overall
performance of the system.
Monitoring Wells: Special wells drilled at
specific locations within, or surrounding, a
hazardous waste site where groundwater can
be sampled at selected depths and studied to
obtain such information as the direction in
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GLOSSARY.
which groundwater flows and the types and
amounts of contaminants present.
National Priorities List (NPL): The EPA's
list of the most serious uncontrolled or aban-
doned hazardous waste sites identified for
possible long-term cleanup under Superfund.
The EPA is required to update the NPL at
least once a year.
Neutrals: Organic compounds that have a
relatively neutral pH, complex structure and,
due to their organic bases, are easily absorbed
into the environment. Naphthalene, pyrene,
and trichlorobenzene are examples of
neutrals.
Nitroaromatics: Common components of
explosive materials, which will explode if
activated by very high temperatures or pres-
sures; 2,4,6-Trinitrotoluene (TNT) is a
nitroaromatic.
Notice Letter: A General Notice Letter
notifies the parties potentially responsible for
site contamination of their possible liability.
A Special Notice Letter begins a 60-day
formal period of negotiation during which the
EPA is not allowed to start work at a site or
initiate enforcement actions against poten-
tially responsible parties, although the EPA
may undertake certain investigatory and
planning activities. The 60-day period may
be extended if the EPA receives a good faith
offer within that period.
On-Scene Coordinator (OSC): The
predesignated EPA, Coast Guard, or Depart-
ment of Defense official who coordinates and
directs Superfund removal actions or Clean
Water Act oil- Oi hazardous-spill corrective
actions.
Operation and Maintenance: Activities
conducted at a site after a cleanup action is
completed to ensure that the cleanup or
containment system is functioning properly.
Organic Chemicals/Compounds: Chemical
substances containing mainly carbon, hydro-
gen, and oxygen.
Outfall: The place where wastewater is
discharged into receiving waters.
Overpacking: Process used for isolating
large volumes of waste by jacketing or encap-
sulating waste to prevent further spread or
leakage of contaminating materials. Leaking
drums may be contained within oversized
barrels as an interim measure prior to removal
and final disposal.
Pentachlorophenoi (PCP): A synthetic,
modified petrochemical that is used as a wood
preservative because of its toxicity to termites
and fungi. It is a common component of
creosotes and can cause cancer.
Perched (groundwater): Groundwater
separated from another underlying body of
groundwater by a confining layer, often clay
or rock.
Percolation: The downward flow or filtering
of water or other liquids through subsurface
rock or soil layers, usually continuing down-
ward to groundwater.
Petrochemicals: Chemical substances
produced from petroleum in refinery opera-
tions and as fuel oil residues. These include
fluoranthene, chrysene, mineral spirits, and
refined oils. Petrochemicals are the bases
from which volatile organic compounds
(VOCs), plastics, and many pesticides are
made. These chemical substances often are
toxic to humans and the environment.
Phenols: Organic compounds that are used
in plastics manufacturing and are by-products
of petroleum refining, tanning, textile, dye,
and resin manufacturing. Phenols are highly
poisonous.
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GLOSSARY
Physical Chemical Separation: The treat-
ment process of adding a chemical to a sub-
stance to separate the compounds for further
treatment or disposal.
Pilot Testing: A small-scale test of a pro-
posed treatment system in the field to deter-
mine its ability to clean up specific contami-
nants.
Plugging: The process of stopping the flow
of water, oil, or gas into or out of the ground
through a borehole or well penetrating the
ground.
Plume: A body of contaminated groundwater
flowing from a specific source. The move-
ment of the groundwater is influenced by such
factors as local groundwater flow patterns, the
character of the aquifer in which groundwater
is contained, and the density of contaminants
[see Migration].
Pollution: Generally, the presence of matter
or energy whose nature, location, or quantity
produces undesired health or environmental
effects.
Polycyclic Aromatic Hydrocarbons or
Polyaromatic Hydrocarbons (PAHs):
PAHs, such as pyrene, are a group of highly
reactive organic compounds found in motor
oil. They are a common component of creo-
sotes and can cause cancer.
Polychlorinated Biphenyls (PCBs): A
group of toxic chemicals used for a variety of
purposes including electrical applications,
carbonless copy paper, adhesives, hydraulic
fluids, microscope immersion oils, and caulk-
ing compounds. PCBs also are produced in
certain combustion processes. PCBs are
extremely persistent in the environment
because they are very stable, non-reactive,
and highly heat resistant Chronic exposure
to PCBs is believed to cause liver damage. It
also is known to bioaccumulate in fatty
tissues. PCB use and sale was banned in
1979 with the passage of the Toxic Sub-
stances Control Act
Polynuclear Aromatic Hydrocarbons
(PNAs): PNAs, such as naphthalene, and
biphenyls, are a group of highly reactive
organic compounds that are a common com-
ponent of creosotes, which can be carcino-
genic.
Polyvinyl Chloride (PVC): A plastic made
from the gaseous substance vinyl chloride.
PVC is used to make pipes, records, raincoats,
and floor tiles. Health risks from high con-
centrations of vinyl chloride include liver
cancer and lung cancer, as well as cancer of
the lymphatic and nervous systems.
Potable Water: Water that is safe for drink-
ing and cooking.
Potentially Responsible Parties (PRPs):
Parties, including owners, who may have
contributed to the contamination at a Su-
perfund site and may be liable for costs of
response actions. Parties are considered PRPs
until they admit liability or a court makes a
determination of liability. PRPs may sign a
Consent Decree or Administrative Order on
Consent to participate in site cleanup activity
without admitting liability.
Precipitation: The removal of solids from
liquid waste so that the solid and liquid
portions can be disposed of safely; the re-
moval of particles from airborne emissions.
Electrochemical precipitation is the use of an
anode or cathode to remove the hazardous
chemicals. Chemical precipitation involves
the addition of some substance to cause the
solid portion to separate.
Preliminary Assessment: The process of
collecting and reviewing available informa-
tion about a known or suspected waste site or
release to determine if a threat or potential
threat exists.
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GLOSSARY.
Pump and Treat: A groundwater cleanup
technique involving the extracting of contami-
nated groundwater from the subsurface and
the removal of contaminants, using one of
several treatment technologies.
Radionuclides: Elements, including radium
and uranium-235 and -238, which break down
and produce radioactive substances due to
their unstable atomic structure. Some are
man-made, and others are naturally occurring
in the environment. Radon, the gaseous form
of radium, decays to form alpha particle
radiation, which cannot be absorbed through
skin. However, it can be inhaled, which
allows alpha particles to affect unprotected
tissues directly and thus cause cancer. Radia-
tion also occurs naturally through the break-
down of granite stones.
RCRA: [See Resource Conservation and
Recovery Act].
Recharge Area: A land area where rainwater
saturates the ground and soaks through the
earth to reach an aquifer.
Record of Decision (ROD): A public docu-
ment that explains which cleanup
alternative(s) will be used to clean up sites
listed on the NPL. It is based on information
generated during the remedial investigation
and feasibility study and consideration of
public comments and community concerns.
Recovery Wells: Wells used to withdraw
contaminants or contaminated groundwater.
Recycle: The process of minimizing waste
generation by recovering usable products that
might otherwise become waste.
Remedial Action (RA): The actual construc-
tion or implementation phase of a Superfund
site cleanup following the remedial design
[see Cleanup].
Remedial Design: A phase of site cleanup,
where engineers design the technical specifi-
cations for cleanup remedies and technolo-
gies.
Remedial Investigation: An in-depth study
designed to gather the data necessary to
determine the nature and extent of contami-
nation at a Superfund site, establish the
criteria for cleaning up the site, identify the
preliminary alternatives for cleanup actions,
and support the technical and cost analyses of
the alternatives. The remedial investigation
is usually done with the feasibility study.
Together they are customarily referred to as
the RI/FS [see Feasibility Study].
Remedial Project Manager (RPM): The
EPA or State official responsible for oversee-
ing cleanup actions at a site.
Remedy Selection: The selection of the
final cleanup strategy for the site. At the few
sites where the EPA has determined that
initial response actions have eliminated site
contamination, or that any remaining con-
tamination will be naturally dispersed with-
out further cleanup activities, a "No Action"
remedy is selected [see Record of Decision].
Removal Action: Short-term immediate
actions taken to address releases of hazardous
substances [see Cleanup].
Residual: The amount of a pollutant remain-
ing in the environment after a natural or
technological process has taken place, e.g.,
the sludge remaining after initial wastewater
treatment, or particulates remaining in air
after the air passes through a scrubbing, or
other, process.
Resource Conservation and Recovery Act
(RCRA): A Federal law that established a
regulatory system to track hazardous sub-
stances from the time of generation to dis-
posal. The law requires safe and secure
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GLOSSARY
procedures to be used in treating, transport-
ing, storing, and disposing of hazardous
substances. RCRA is designed to prevent
new, uncontrolled hazardous waste sites.
Retention Pond: A small body of liquid
used for disposing of wastes and containing
overflow from production facilities. Some-
times retention ponds are used to expand the
capacity of such structures as lagoons to store
waste.
Riparian Habitat: Areas adjacent to rivers
and streams that have a high density, diver-
sity, and productivity of plant and animal
species relative to nearby uplands.
Runoff: The discharge of water over land
into surface water. It can carry pollutants
from the air and land and spread contamina-
tion from its source.
Scrubber: An air pollution device that uses a
spray of water or reactant or a dry process to
trap pollutants in emissions.
Sediment: The layer of soil, sand, and
minerals at the bottom of surface waters, such
as streams, lakes, and rivers, that absorbs
contaminants.
Seeps: Specific points where releases of
liquid (usually leachate) form from waste
disposal areas, particularly along the lower
edges of landfills.
Seepage Pits: A hole, shaft, or cavity in the
ground used for storage of liquids, usually in
the form of leachate, from waste disposal
areas. The liquid gradually leaves the pit by
moving through the surrounding soil.
Septage: Residue remaining in a septic tank
after the treatment process.
Sinkhole: A hollow depression in the land
surface in which drainage collects; associated
with underground caves and passages that
facilitate the movement of liquids.
Site Characterization: The technical pro-
cess used to evaluate the nature and extent of
environmental contamination, which is
necessary for choosing and designing cleanup
measures and monitoring their effectiveness.
Site Inspection: The collection of informa-
tion from a hazardous waste site to determine
the extent and severity of hazards posed by
the site. It follows, and is more extensive
than, a preliminary assessment. The purpose
is to gather information necessary to score the
site, using the Hazard Ranking System, and to
determine if the site presents an immediate
threat that requires a prompt removal action.
Slag: The fused refuse or dross separated
from a metal in the process of smelting.
Sludge: Semi-solid residues from industrial
or water treatment processes that may be
contaminated with hazardous materials.
Slurry Wall: Barriers used to contain the
flow of contaminated groundwater or subsur-
face liquids. Slurry walls are constructed by
digging a trench around a contaminated area
and filling the trench with an impermeable
material that prevents water from passing
through it. The groundwater or contaminated
liquids trapped within the area surrounded by
the slurry wall can be extracted and treated.
Smelter: A facility that melts or fuses ore,
often with an accompanying chemical change,
to separate the metal. Emissions from smelt-
ers are known to cause pollution.
Soil Gas: Gaseous elements and compounds
that occur in the small spaces between par-
ticles of soil. Such gases can move through
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GLOSSARY.
or leave the soil or rock, depending on
changes in pressure.
Soil Vapor Extraction: A treatment process
that uses vacuum wells to remove hazardous
gases from soil.
Soil Washing: A water-based process for
mechanically scrubbing soils in-place to
remove undesirable materials. There are two
approaches: dissolving or suspending them in
the wash solution for later treatment by
conventional methods, and concentrating
them into a smaller volume of soil through
simple particle size separation techniques [see
Solvent Extraction].
Stabilization: The process of changing an
active substance into inert, harmless material,
or physical activities at a site that act to limit
the further spread of contamination without
actual reduction of toxicity.
Solidification/Stabilization: A chemical or
physical reduction of the mobility of hazard-
ous constituents. Mobility is reduced through
the binding of hazardous constituents into a
solid mass with low permeability and resis-
tance to leaching.
Solvent: A substance capable of dissolving
another substance to form a solution. The
primary uses of industrial solvents are as
cleaners for degreasing, in paints, and in
Pharmaceuticals. Many solvents are flam-
mable and toxic to varying degrees.
Solvent Extraction: A means of separating
hazardous contaminants from soils, sludges,
and sediment, thereby reducing the volume of
the hazardous waste that must be treated. It
generally is used as one in a series of unit
operations. An organic chemical is used to
dissolve contaminants as opposed to water-
based compounds, which usually are used in
soil washing.
Sorption: The action of soaking up or at-
tracting substances. It is used in many pollu-
tion control systems.
Stillbottom: Residues left over from the
process of recovering spent solvents.
Stripping: A process used to remove volatile
contaminants from a substance [see Air
Stripping].
Sumps: A pit or tank that catches liquid
runoff for drainage or disposal.
Superfund: The program operated under the
legislative authority of the CERCLA and
Superfund Amendments and Reauthorization
Act (SARA) to update and improve environ-
mental laws. The program has the authority
to respond directly to releases or threatened
releases of hazardous substances that may
endanger public health, welfare, or the envi-
ronment. The "Superfund" is a trust fund that
finances cleanup actions at hazardous waste
sites.
Surge Tanks: A holding structure used to
absorb irregularities in flow of liquids, includ-
ing liquid waste materials.
Swamp: A type of wetland that is dominated
by woody vegetation and does not accumulate
peat moss deposits. Swamps may be fresh or
saltwater and tidal or non-tidal [see Wet-
lands].
Thermal Treatment: The use of heat to
remove or destroy contaminants from soil.
Treatabiiity Studies: Testing a treatment
method on contaminated groundwater, soil,
etc., to determine whether and how well the
method will work.
Trichloroethylene (TCE): A stable, color-
less liquid with a low boiling point. TCE has
many industrial applications, including use as
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GLOSSARY
a solvent and as a metal degreasing agent.
TCE may be toxic to people when inhaled,
ingested, or through skin contact and can
damage vital organs, especially the liver [see
Volatile Organic Compounds],
Unilateral [Administrative] Order: [see
Administrative Order].
Upgradient: An upward hydrologic slope;
demarks areas that are higher than contami-
nated areas and, therefore, are not prone to
contamination by the movement of polluted
groundwater.
Vacuum Extraction: A technology used to
remove volatile organic compounds (VOCs)
from soils. Vacuum pumps are connected to a
series of wells drilled to just above the water
table. The wells are sealed tightly at the soil
surface, and the vacuum established in the
soil draws VOC-contaminated air from the
soil pores into the well, as fresh air is drawn
down from the surface of the soil.
Vegetated Soil Cap: A cap constructed with
graded soils and seed for vegetative growth,
to prevent erosion [see Cap].
Vitrification: The process of electrically
melting wastes and soils or sludges to bind
the waste in a glassy, solid material more
durable than granite or marble and resistant to
leaching.
Volatile Organic Compounds (VOCs):
VOCs are manufactured as secondary petro-
chemicals. They include light alcohols,
acetone, trichloroethylene, perchloroethylene,
dichloroethylene, benzene, vinyl chloride,
toluene, and methylene chloride. These
potentially toxic chemicals are used as sol-
vents, degreasers, paints, thinners, and fuels.
Because of their volatile nature, they readily
evaporate into the air, increasing the potential
exposure to humans. Due to their low water
solubility, environmental persistence, and
widespread industrial use, they are commonly
found in soil and groundwater.
Waste Treatment Plant: A facility that uses
a series of tanks, screens, filters, and other
treatment processes to remove pollutants from
water.
Wastewater: The spent or used water from
individual homes or industries.
Watershed: The land area that drains into a
stream or other water body.
Water Table: The upper surface of the
groundwater.
Weir: A barrier to divert water or other
liquids.
Wetland: An area that is regularly saturated
by surface or groundwater and, under normal
circumstances, is capable of supporting
vegetation typically adapted for life in satu-
rated soil conditions. Wetlands are critical to
sustaining many species of fish and wildlife.
Wetlands generally include swamps, marshes,
and bogs. Wetlands may be either coastal or
inland. Coastal wetlands have salt or brackish
(a mixture of salt and fresh) water, and most
have tides, while inland wetlands are non-
tidal and freshwater. Coastal wetlands are an
integral component of estuaries.
Wildlife Refuge: An area designated for the
protection of wild animals, within which
hunting and fishing are either prohibited or
strictly controlled.
79
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APPENDIX B
Information
Repositories
for
NPL Sites
in Delaware
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83
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