EPA/540/4-90/050
                                              September 1990
 NATIONAL PRIORITIES LIST SITES:
                  Wyoming
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
       Office of Emergency & Remedial Response
            Office of Program Management
              Washington, D.C. 20460

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If you wish to purchase copies of any additional State volumes or the National
Overview volume, Superfund: Focusing on the Nation at Large, contact:
            National Technical Information Service (NTIS)
            U.S. Department of Commerce
            5285 Port Royal Road
            Springfield, VA 22161
            (703) 487-4600

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                                              PAGE
INTRODUCTION:
A Brief Overview..*>.	...»	.....	iii

SUPERFUND:
How Does the Program Work to Clean Up Sites	vii

How To:
Using the State Volume	....	............xvii

NPL SITES:
A State Overview	..	..	xxi

THE NPL PROGRESS REPORT	xxiii

NPL: Site Fact Sheets	.....1


GLOSSARY:
Terms Used in the Fact Sheets	G-l

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11

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WHY THE SUPERFUND
PROGRAM?

       s the 1970s came to a
       close, a series of head-
       line 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. Hazard-
ous waste buried there over a
25-year period contaminated
streams and soil, and endan-
gered the health of nearby
residents. The result: evacu-
ation 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 environment
were threatened, lives were
disrupted, property values
depreciated. It became in-
creasingly clear that there
were large numbers of serious
hazardous waste problems
that were falling through the
cracks  of existing environ-
mental laws. The magnitude
of these emerging problems
moved Congress to enact the
Comprehensive Environ-
mental Response, Compensa-
tion, and Liability Act in 1980.
CERCLA — commonly
known as the Superfund —
was the first Federal law
established to deal with the
dangers posed by the
Nation's hazardous waste
sites.
After Discovery, the Problem
Intensified

Few realized the size of the
problem until EPA began the
process of site discovery and
site evaluation.  Not hun-
dreds, but thousands of
potential hazardous waste
sites existed, and they pre-
sented the Nation with some
of the most complex pollution
problems it had ever faced.

In the 10 years since the
Superfund program began,
hazardous waste has surfaced
as a major environmental
concern in every part of the
United States. It wasn't just
the land that was contami-
nated by past disposal prac-
tices. Chemicals in the soil
were spreading into the
groundwater (a source of
drinking water for many) and
into streams, lakes, bays, and
wetlands. Toxic vapors
contaminated the air at some
sites, while at others improp-
erly disposed or stored
wastes threatened the health
of the surrounding commu-
nity and the environment.
EPA Identified More than
1,200 Serious Sites

EPA has identified 1,236
hazardous waste sites as the
most serious in the Nation.
These sites comprise the
"National Priorities List":
sites targeted for cleanup
under the Superfund. But site
discoveries continue, and
EPA estimates that, while
some will be deleted after
lengthy cleanups, this list,
commonly called the NPL,
will continue to grow by ap-
proximately 100 sites per
year, 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 recog-
nized that the Federal govern-
ment could not and should
not address all environmental
problems stemming from past
disposal practices.  Therefore,
the EPA was directed to set
priorities and establish a list
of sites to target. Sites on the
NPL (1,236) are thus a rela-
                                          m

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lively small subset of a larger
inventory of potential hazard-
ous waste sites, but they do
comprise the most complex
and environmentally compel-
ling cases. EPA has logged
more than 32,000 sites on its
National hazardous waste
inventory, and assesses each
site within one year of being
logged. In fact, over 90 per-
cent of the sites on the inven-
tory have been assessed. Of
the assessed sites, 55 percent
have been found to require no
further Federal action because
they did not pose significant
human health or environ-
mental risks. The remaining
sites are undergoing further
assessment to determine if
long-term Federal cleanup
activities are appropriate.
EPA IS MAKING
PROGRESS ON SITE
CLEANUP

The goal of the Superfund
program is to tackle immedi-
ate dangers first, and then
move through the progressive
steps necessary to eliminate
any long-term risks to public
health and the environment.

The Superfund responds
immediately to sites posing
imminent threats to human
health and the environment
at both NPL sites and sites
notontheNPL. The purpose
is to stabilize, prevent, or
temper the effects of a haz-
ardous release, or the threat
of one. 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 immi-
nent threats is one of the
Superfund's most noted
achievements. Where immi-
nent threats to the public or
environment were evident,
EPA has completed or moni-
tored emergency actions that
attacked the most serious
threats to toxic exposure in
more than 1,800 cases.

The ultimate goal for a haz-
ardous waste site on the NPL
is a permanent solution to an
environmental problem that
presents a serious (but not an
imminent) threat to the public
or environment.  This often
requires a long-term effort. In
the last four years, EPA has i
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. And in
1989 more sites than ever
reached the construction
stage of the Superfund
cleanup process.  Indeed
construction starts increased
by over 200 percent between
late 1986 and 1989!  Of the
sites currently on the NPL,
more than 500 — nearly half
— have had construction
cleanup activity. In addition,
over 500 more sites are pres-
ently in the investigation
stage to determine the extent
of site contamination, and to
identify appropriate cleanup
remedies.  Many other sites
with cleanup remedies se-
lected are poised for the start
of cleanup construction activ-
ity. Measuring success by
"progress through the
cleanup pipeline/' EPA is
clearly gaining momentum.
EPA MAKES SURE
CLEANUP WORKS

EPA has gained enough
experience in cleanup con-
struction to understand that
environmental protection
does not end when the rem-
edy is in place. Many com-
plex technologies — like
those designed to clean up
groundwater •— must operate
for many years in order to
accomplish their objectives.

EPA's hazardous waste site
managers are committed  to
proper operation and mainte-
nance of every remedy con-
structed. 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, EPA does not
abandon a site even after the
cleanup work is done.  Every
                                          IV

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 five years the Agency reviews
 each site where residues from
 hazardous waste cleanup still
 remain to ensure that public
 and environmental health are
 still being safeguarded, EPA
 will correct any deficiencies
 discovered and 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. EPA's job is to
analyze the hazards and
deploy the experts, but the
Agency needs citizen input as
it makes choices for affected
communities.

Because the people in a
community with a Superfund
site will be those most di-
rectly affected by hazardous
waste problems and cleanup
processes, EPA encourages
citizens to get involved in
cleanup decisions. Public in-
volvement and comment does
influence EPA cleanup plans
by providing valuable infor-
mation about site conditions,
community concerns and
preferences.

This State volume and the
companion National Over-
view volume provide general
Superfund background
information and descriptions
of activities at each State NPL
site. These volumes are
 intended to clearly describe
 what the problems are, what
 EPA and others participating
 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
 IN TANDEM

 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. The public
 should understand the chal-
 lenges involved in hazardous
 waste cleanup and the deci-
 sions we must make — as a
 Nation —- in finding the best
 solutions.

 The National Overview
 volume — Superfund: Focus-
 ing on the Nation at Large —
 accompanies this State vol-
 ume.  The National Overview
 contains important informa-
 tion to help you understand
 the magnitude and challenges
 facing the  Superfund pro-
 gram 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, the Super-
fund program's successes in
cleaning up the Nation's
 serious hazardous waste sites,
 and the vital roles of the
 various participants in the
 cleanup process.

 This State volume compiles
 site summary fact sheets on
 each State site being cleaned
 up under the Superfund
 program. These sites repre-
 sent the most serious hazard-
 ous waste problems in the
 Nation, and require the most
 complicated and costly site
 solutions yet encountered.
 Each State book gives a
 "snapshot" of the conditions
 and cleanup progress that has
 been made at each NPL site in
 the State through the first half
 of 1990. Conditions change as
 our cleanup efforts continue,
 so these site summaries will
 be updated periodically to
 include new information on
 progress being made.

 To help you understand the
 cleanup accomplishments
 made at these sites, this State
 volume includes a description
 of the process for site discov-
 ery, threat evaluation and
 long-term cleanup of Super-
 fund sites. This description
 —• How Does the Program
 Work to Clean Up Sites? —
 will serve as a good reference
 point from which to review
 the cleanup status at specific
sites.  A glossary also is
included at the back of the
book that defines key terms
used in the site fact sheets as
they apply to hazardous
waste management.

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TA

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      The diverse problems posed by the Nation's hazardous
      waste sites have provided EPA with the challenge to
      establish a consistent approach for evaluating and
cleaning up the Nation's most serious sites.  To do this, EPA
had to step beyond its traditional role as a regulatory agency
to develop processes and guidelines for each step in these
technically complex site cleanups. EPA has established proce-
dures to coordinate the efforts of its Washington, D.C. Head-
quarters program offices and its front-line staff in 10 Regional
Offices with the State governments, contractors, and private
parties who are participating in site cleanup. An important
part of the process is that any time during cleanup, work can
be led by EPA or the State or, under their monitoring, by
private parties who are potentially responsible for site con-
tamination.

The process for discovery of the site, evaluation of threat, and
long-term cleanup of Superfund  sites is summarized in the
following pages. The phases of each of these steps are high-
lighted within the description. The flow diagram below pro-
vides a summary of this three step 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
    STEP 3

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
                                         FIGURE 1
 Although this State book provides a current "snapshot" of site progress made only by emer-
 gency actions and long-term cleanup actions at Superfund sites, it is important to understand
 the discovery and evaluation process that leads up to identifying and cleaning up these most
 serious uncontrolled or abandoned hazardous waste sites in the Nation. This discovery and
 evaluation process is the starting point for this summary description.
                                           VII

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 How does EPA learn,
 about potential
 hazardous waste
 'sites?
STEP 1:  SITE DISCOVERY AND EMERGENCY
           EVALUATION

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. Or there may be an explosion or fire
which alerts the State or local authorities to a problem. Rou-
tine investigations by State and local governments, and re-
quired reporting and inspection of facilities that generate,
treat, store, or dispose of hazardous waste also help keep EPA
informed about either actual or potential threats of hazardous
substance releases. All reported sites or spills are recorded in
the Supeffund inventory (CERCLIS) for further investigation
to determine whether they will require cleanup.
I What happens if
sphere Is an imnodnenl
I danger?
As soon as a potential hazardous waste site is reported, EPA
determines whether there is an emergency requiring an imme-
diate 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
contaminated area to keep people away or temporarily relo-
cating residents until the danger is addressed, to providing
bottled water to residents 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.
rif there isn't an
fe                     A
i imminent danger,
| how does EPA ^ ^ ^
I determine what, if
*Hny, cleanup actions
 should be taken?
STEP 2:  SITE THREAT EVALUATION

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 contaminated well water.
But now it's time to figure out what is contaminating the
drinking water supply and the best way to clean it up.  Or
                                      vm

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EPA may determine that there is no imminent danger from a
site, so now 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 requires a long-term cleanup action.

Once a site is discovered and any needed emergency actions
are taken, EPA or the State collects all available background
information 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 assess-
ment of its potential hazards. This is a quick review of readily
available information to answer the questions:
*   Are hazardous  substances likely to be present?
«   How are they contained?

•   How might contaminants spread?

•   How close is the nearest well, home, or natural resource
    area like a wetland or animal sanctuary?

•   What may be harmed —• the land, water, air, people,
    plants, or animals?

Some sites do not require further action because the prelimi-
nary assessment shows that they don't threaten public health
or the environment. 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 32,000
sites maintained in this inventory.
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 polluting the
environment — such as runoff into nearby streams. They also
check to see if people (especially children) have access to the
site.
assessment shows
that a seriottsthreat
may exist^"what's i&e
next
Information collected during the site inspection is used to
identify the sites posing the most serious threats to human
health and the environment. This way EPA can meet the
                 jse--
                                          IX

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       do people find
     whether BPA^
^considers a site a^v'
| national priorit^ for
I cleanup using n
-Superfund money? ^
                    •• x «.-.t "•
f
f
requirement that Congress gave them to use Superfund mo-
nies only on the worst hazardous waste sites in the Nation.

To identify the most serious sites, EPA developed the Hazard
Ranking System (HRS). The HRS is the scoring system 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 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 potentially
affected by contamination at the site.

Only sites with high enough health and environmental risk
scores are proposed to be added to EPA's National Priorities
List (NPL). That's why there are 1,236 sites are on the NPL,
but there are more than 32,000 sites in the Superfund inven-
tory.  Only NPL sites can have a long-term cleanup paid for
from the national hazardous waste trust fund — the Super-
fund. But the Superfund can and does pay for emergency
actions performed at any site, whether or not it's on the NPL.
The public can find out whether a site that concerns them is
on the NPL by calling their Regional EPA office at the number
listed in this book.

The proposed NPL identifies sites that 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 added 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. Updated at least once a year, it's only after
public comments are considered that these proposed worst
sites are officially added to the NPL.

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 capabili-
ties, and available technologies. Many States also have their
own list of sites that require cleanup; these often contain sites
not on the NPL that are scheduled to be cleaned up with State
money. And it should be said again that any emergency action
needed at a site can be performed by the Superfund whether
 or not a site is on the NPL.

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STEP 3: LONG-TERM CLEANUP ACTIONS

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 challenges, there is no single all-purpose solu-
tion. So a five-phase "remedial response" process is used to
develop consistent and workable solutions to hazardous waste
problems across the Nation:
1.  Investigate in detail the extent of the site contamination:
   remedial investigation,

2.  Study the range of possible cleanup remedies: feasibility
   study,

3.  Decide which remedy to use: Record of Decision or ROD,

4.  Plan the remedy: remedial design, and
5.  Carry out the remedy: remedial action.

This remedial response process is a long-term effort to provide
a permanent solution to an environmental problem that
presents a serious, but not an imminent threat to the public or
environment.

The first two phases of a long-term cleanup are a combined
remedial investigation and feasibility 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 EPA or the State or, under their monitor-
ing, by private parties.

Like the initial site inspection described earlier, a remedial
investigation involves an examination of site data in order to
better define the  problem. But 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 is information that allows
EPA to select the cleanup strategy that is best suited to a
particular site or to determine that no cleanup is needed.
- After a site Is added  ,,,
 to the NPL/ what ate
     steps to
       <''».' $'..
                                          XI

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                              Placing a site on the NPL does not necessarily mean that
                              cleanup is needed, It is possible for 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 preliminary and conservative ]
                              assessment of potential risk. During subsequent site investiga-
                              tions, the EPA may find either that there is no real threat or
                              that the site does not pose significant human health or envi-
                              ronmental risks.
; How are cleanup
-- alternatives

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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, 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 community know
where they can get copies of the study and other reference
documents concerning the site.

The public has a minimum of 30 days to comment on the
proposed cleanup plan after it is published. These comments
can either be written or given verbally at public meetings that
EPA or the State are required to hold. Neither EPA nor the
State can select the final cleanup remedy without evaluating
and providing written answers to specific community com-
ments and concerns.  This "responsiveness summary" is part
of 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 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 technologies are needed to clean up a single
site.
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 remedy 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 6 months to 2
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
 If evwy cleamtp
; action needs to be
 rfbred to a site, does
 t&e design of the
         tteed to b&
          too?
                                         XUl

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 SUPERFUND
I Once the design is
  complete, how long
  does it
 s,
 * actually clean up the
 «site and
 5 does it cost?
 Once the cleanup     - \
 Action is complete, is   1
 J&e site automatically   -
 "deleted" from the    >% *
 NPL?                *  ^
i
i
Ir

 r




I
                   f  5<
               if    (. < ' <


             }^"    % " "\*
             :     ">*   1  x\x
                             site, special plans for environmental protection, worker safety,
                             regulatory compliance, and equipment decontamination.
                             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 decontaminate them — an
                             action that takes limited time and money. In most cases,
                             however, a remedial action may involve different and expen-
                             sive 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 described in
                             the ROD may need to be modified because of new contami-
                             nant information discovered or difficulties that were faced
                             during the early cleanup activities. Taking into account these
                             differences, a remedial cleanup action takes an average of 18
                             months to complete and costs an average of $26 million per
                             site.
                             No. The deletion of a site from the NPL is anything but auto-
                             matic. For example, cleanup of contaminated groundwater
                             may take up to 20 years or longer. Also, in some cases the
                             long-term monitoring of the remedy is required to ensure that
                             it is effective. After construction of certain remedies, opera-
                             tion and maintenance (e.g., maintenance of ground cover,
                             groundwater monitoring, etc.) or continued pumping and
                             treating of groundwater, may be required to ensure that the
                             remedy continues to prevent future health hazards or environ-
                             mental  damage, and ultimately meets the cleanup goals    ;
                             specified in the ROD. Sites in this final monitoring or opera-
                             tional stage of the cleanup process are designated as "con-
                             struction completed".

                             If s not  until a site cleanup meets all the goals and monitoring
                             requirements of the selected remedy that EPA can officially
                             propose the site for "deletion" from the NPL. And it's not
                             until public comments are taken into consideration that a site
                             can actually be deleted from the NPL.  Deletions that have
                             occurred are included in the "Construction Complete" cate-
                             gory in the progress report found later in this book.
                                       XIV

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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 contamination
problems at a site, Although 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 EPA, and must meet the same standards
required for actions financed through the Superfund.

Because these enforcement actions can be lengthy, 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 for repaying the money
EPA spends in cleaning up the site.

Whenever possible, EPA and the Department of Justice use
their legal enforcement authorities to require responsible
parties to pay for site cleanups, thereby preserving the Super-
fund for emergency actions and sites where no responsible
parties can be identified.
Can EPA make patties
             for tti-e,-.,
                                          XV

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TAX

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       The Site Fact Sheets
     ,„, presented in this book
       are comprehensive
summaries that cover a broad
range of information. The
fact sheets describe hazard-
ous waste sites on the Na-
tional Priorities List (NPL)
and their locations, as well as
the conditions leading to their
listing ("Site Description").
They list the types of con-
taminants that have been dis-
covered and related threats to
public and ecological health
("Threats and Contami-
nants"). "Cleanup Ap-
proach" presents an overview
of the cleanup activities
completed, underway, or
planned.  The fact sheets
conclude with a brief synop-
sis of how much progress has
been made on protecting
public health and the envi-
ronment. The summaries also
pinpoint other actions, such
as legal efforts to involve pol-
luters responsible for site
contamination and commu-
nity concerns.

The following two pages
show a generic fact sheet and
briefly describes the informa-
tion under each section. The
square "icons" or symbols ac-
companying the text allow
the reader to see at a glance
which environmental re-
sources are affected and the
status of cleanup activities.
Icons in the Threats
and Contaminants
Section

       Contaminated
       Groundwater re-
       sources in the vicinity
or underlying the site.
(Groundwater is often used
as a drinking water source.)
       Contaminated Sur-
       face Water and
       Sediments on or near
the site. (These include lakes,
ponds, streams, and rivers.)
       Contaminated Air in
       the vicinity of the
       site. (Pollution is
usually periodic and involves
contaminated dust particles
or hazardous gas emissions.)
       Contaminated Soil
       and Sludges on or
       near the site.
       Threatened or
       contaminated Envi-
       ronmentally Sensi-
tive Areas in the vicinity of
the site. (Examples include
wetlands and coastal areas,
critical habitats.)
Icons in the Response
Action Status Section
               Actions
         have been taken or
        are underway to
eliminate immediate threats
                                       Site Studies at the
                                       site are planned or
                                       underway.
          Remedy Selected
          indicates that site
          investigations have
          been concluded
          and EPA has se-
lected a final cleanup remedy
for the site or part of the site.
           Remedy Design
           means that engi-
           neers are prepar-
           ing 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 — are currently
underway.
          Cleanup Complete
          shows that all
          cleanup goals have
          been achieved for
the contaminated site or part
of the site.
                                         xvii

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      Site Responsibility

 Identifies the Federal, State,
 and/or potentially responsible
 parties that are taking
 responsibility for cleanup
 actions at the site.
                                      EPA REGION

                                   CONGRESSIONAL DIST
                                       County Name
                       SITE NAME
                       STATE
                       EPA ID# ABCOOOOOOOO
                     Site Description
           Threats and Contaminants
                      Cleanup Approach
   NPL Listing
   History

Dates when the site
was Proposed,
made Final, and
Deleted from the
NPL
                        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.
   Ill
%Cc
                                   XVU1

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             WHAT THE FACT SHEETS CONTAIN
                           Site Description

This section describes the location and history of the site.  It includes
descriptions of the most recent activities and past actions at the site that have
contributed to the contamination. Population estimates, land usages, and nearby
resources give readers background on the local setting surrounding the site.
Throughout the site description and other sections of the site summary, technical
or unfamiliar terms that are italicized are presented in the glossary at the end of
the book. Please refer to the glossary for more detailed explanation or definition
of the terms.
                        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, grpundwater, surface water, soil and
     contamination to environmentally sensitive areas) are included in the margins
     of this section.  Potential threats to residents and the surrounding
     environments arising from the site contamination are also described.  Specific
     contaminants and contaminant groupings are italicized and explained in more
     detail in the glossary.
                                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 are often 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 description.
                          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 EPA to achieve
 site cleanup or other facts pertaining to community involvement with the site
 cleanup process are reported here.
                                        xix

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The feet sheets are arranged
in alphabetical order by site
name. Because site cleanup is
a dynamic and gradual
process, all site information is
accurate as of the date shown
on the bottom of each page.
Progress is always being
made at NPL sites, and EPA
will periodically update the
Site Fact Sheets to reflect
recent actions and publish
updated State volumes.
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. EPA is
committed to involving the
public in the decisionmaking
process associated with
hazardous waste cleanup.
The Agency solicits input
from area residents in com-
munities 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 cleanups
take many forms and can
affect communities in differ-
ent ways.  Local traffic may
be rerouted, residents may be
relocated, temporary 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
EPA intends to clean up the
site. You must understand
the cleanup alternatives being
proposed for site cleanup and
how residents may be af-
fected by each one. You also
need to have some idea of
how your community intends
to use the site in the future
and to know what the com-
munity can realistically
expect once the cleanup is
complete.

EPA wants to develop
cleanup methods that meet
community needs, but the
Agency can only 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 in-
volved, and assure that
hazardous waste cleanup at
"your" site considers your
community's concerns.
                                         xx

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      NPL  Sites i
      State of Wyor
Wyoming is a mountainous state lying in the high western plateaus of the Great Plains
and is bordered by Montana to the north, Colorado and Utah to the south, South Dakota
and Nebraska to the east, and Idaho, Montana, and Utah to the west.  The State covers
97,809 square miles consisting of the Great Plains, the foothills of the Rocky Moun-
tains, and the Continental Divide.  Wyoming experienced a 2.1 percent increase in
population through the 1980s and currently has approximately 479,000 residents, rank-
ing 50th in U.S. populations.  Principal state industries include mineral extraction; tour-
ism and recreation; agriculture.  Wyoming manufacturing produces refined petroleum
products, foods, wood products, and stone, clay, and glass products.
How Many Wyoming Sites
Are on the NPL?
Proposed Sites
Final Sites
Deleted Sites
1
2
Q
3
             Where Are the NPL Sites Located?
Cong. District 01
3 sites
      How are Sites Contaminated and What are the Principal* Chemicals ?
   4 --
   3--
   2 --
 *
   1 --
       GW  Soil  SW   Sed

        Contamination Area
                        Groundwater: Groundwater
                        Volatile organic compounds
                        (VOCs), creosotes (organics), and
                        petrochemicals.
                        Soil: Volatile organic compounds
                        (VOCs), heavy metals
                        (inorganics), dioxins, creosotes
                        (organics), and petrochemicals.
                        Surface Water and Sediments:
                        Volatile organic compounds
                        (VOCs), dioxins, and creosotes
                        (organics).
                        *Appear at 33% or more sites
State Overview
                                                                       continued

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             Where are the Sites in the Superfund Cleanup Process*?
       Site
     Studies
Remedy ^^^ Remedy
Selected ^^^" Design
Cleanup
Ongoing
Construction
  Complete
    Initial actions have been taken at 2 sites as interim cleanup measures.
                          Who Do I Call with Questions?
The following pages describe each NPL site in Wyoming, providing specific information
on threats and contaminants, cleanup activities, and environmental progress. Should
you have questions, please call one of the offices listed below:
       Wyoming Superfund Office
       EPA Region VI11  Superfund Office              '.
       EPA Region VIII  Superfund Community Relations
       EPA Headquarters Public Information Center
       EPA Superfund Hotline
                                      (307) 777-7752
                                      (303)293-1720
                                      (303)294-1144
                                      (202) 475-7751
                                      (800) 424-9346
'Cleanup status reflects phase of site activities rather than administrative accomplishments.
State Overview
                                       XXII

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The NPL Progress Report	

The following Progress Report lists the State 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 Superfund cleanup process are arrayed across the top of the
chart, and each site's progress through these steps is represented by an arrow (*-) which
indicates the current stage of cleanup at the site.

Large and complex sites are often 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
different 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.

•K  An arrow in the "Initial Response" category indicates that an emergency cleanup or
    initial action has been completed or is currently underway. Emergency or initial  actions
    are taken as an interim measure to provide immediete relief from exposure to
    hazardous site conditions or to stabilize a site to prevent further contamination.
*-  An arrow in the "Site Studies" category indicates that an investigation to determine the
    nature and extent of the contamination at the site is currently ongoing or planned to
    begin in 1991.
•>-  An 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 in .the Progress Report are
    discontinued at the "Remedy Selection" step and resume in the final "Construction
    Complete" category.

*-  An arrow at the "Remedial Design" stage indicates that engineers are currently
    designing the technical specifications for the selected cleanup remedies and
    technologies.

*-  An arrow marking the "Cleanup Ongoing" category means that final cleanup actions
    have been started at the site and are currently underway.
+-  A arrow in the "Construction Complete" category is used on/ywhen 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 may currently
    be undergoing long-term pumping and treating of groundwater, operation and
    maintenance or monitoring to ensure that the completed cleanup actions continue to
    protect human health and the environment.

The sites are listed in alphabetical order. Further information on the activities and progress
at each site is given in the site "Fact Sheets" published in this volume.
                                     XXlll

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Progress Toward Cleanup at NPL Sites in the State of Wyoming
Page
Site Name
County
               Initial     Site     Remedy Remedy  Cleanup  Construction
NPL   Date      Response  Studies  Selected Design   Ongoing  Complete
1    BAXTER/UNION PACIFIC TIE TREATING   ALBANY

3    F.E. WARREN AIR FORCE BASE         LARAMIE

5    MYSTERY BRIDGE ROAD/HWY 20       NATRONA
                                         Final   09/08/83

                                         Final   02/21/90

                                         Prop   06/24/88
                                                       XXIV

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   PACIFIC

   TIE  TREATING
   WYOMING
   EPA ID# WYD0611124 70
                                      REGION 8
                              CONGRESSIONAL DIST. 01
                                      Albany County
                                1 3/4 miles southwest of Laramie
Site Description
   The Union Pacific Railroad, or its contractor, treated railroad ties at the Baxter/Union
   Pacific Tie Treating site between 1886 and 1983 using various chemicals including zinc
   chloride, a mixture of creosote oil and an asphalt-based oil, and pentachlorophenol
   (PCP). During the operation's first 70 years, workers disposed of process wastes in the
   Laramie waste collection ponds. Contamination outside these ponds was discovered in
   1981 during groundwater monitoring required by the EPA. Approximately 140 acres of
   the property's 700 acres are currently polluted with oils and wood treating chemicals.
   The railroad voluntarily ceased operations at the site in 1983.  The City of Laramie has a
   population of 24,000. The public water supply for Laramie is not connected to the site;
   the city uses a reservoir fed by the Laramie River several miles upriver. Contaminated
   water beneath the site is not used for drinking, and domestic private wells near the site
   were sampled and found clean.
  site Responsibility:  jhis site is being addressed through
                     Federal and potentially responsible
                     parties'actions.
                                  NPL LISTING HISTORY

                                 Proposed Date: 12/30/82
                                   Final Date: 09/08/83
                 Threats and Contaminants
               Groundwater, soil, and sediments contained numerous polycydic
               aromatic hydrocarbons (PAHs) including PCP.  PCP levels were shown to
               be higher downgradient, indicating movement of contaminants from the
               site. The public drinking supply is protected, as it is drawn from above the
               contamination area; however, direct contact with site contaminants is a
               possible health threat.
  March 1990
NPL HAZARDOUS WASTE SITES
                1
                                                                        continued

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                                                BAXTER/UNION PACIFIC TIE TREATING
Cleanup Approach
  This site is being addressed in two long-term remedial phases focusing on source
  control and cleanup of the contaminated groundwater.
  Response Action Status
              Source Control: The EPA selected an interim remedy to control the
              source of contamination and to address groundwater cleanup in 1986,  The
              remedy features an isolation system designed to keep contaminated
  groundwater and soil from moving off site while more permanent remedies are
  planned. This remedy includes: (1) realigning the Laramie River Channel 150 feet
  farther west from the site to reduce the chance of contamination; (2) constructing a
  slurry wall through the soil and bedrock around contaminated areas; (3) draining and
  pumping groundwater against its natural flow to keep it from seeping off site and
  through the slurry wall; (4) treating withdrawn groundwater with activated carbon to
  decontaminate it; (5) discharging this cleaned water into the Laramie River, under State
  and Federal permits; and (6) monitoring the groundwater to track the effectiveness of
  the system. Union Pacific Railroad designed the interim remedy and carried out its
  cleanup steps from 1986 to 1987.

              Groundwater:  In 1990 Union Pacific completed a study which included
              the results of several groundwater treatment pilot studies. The final
              design of the remedy is scheduled for 1991, and construction is scheduled
              to begin in 1992.
   Environmental Progress
  The cleanup actions to contain and clean up contaminated groundwater have greatly
  reduced the potential for exposure to contaminated materials at the Baxter/Union
  Pacific Tie Treating site while further cleanup activities are completed,

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   RE.  WAKKE;
   FORCE
   WYOMIN
   EPA ID# WY5
                                    REGION 8
                             CONGRESSIONAL DIST. 01
                                    Laramle County
                                       Cheyenne
Site Description
   The 5,866-acre RE, Warren Air Force Base site initially began as a U.S. Army cavalry
   outpost in 1867 and has since served a number of military functions.  In 1947, control
   of the facility was transferred to the U.S. Air Force, and it became a Strategic Air
   Command base in 1958.  Waste generation at the facility has consisted primarily of
   spent solvents from equipment cleaning and various maintenance operations. The Air
   Force also maintained an acid well used for spent battery acid disposal. While five
   landfills are located at the facility and hold various wastes, only one landfill is presently
   in operation.  Two fire protection areas involved extensive use of various fuels and
   combustible materials for fire training exercises. Initially, 25 areas were identified
   where hazardous materials might have been used, stored, treated, or disposed.
   Agricultural lands and industrial developments surround the base. Approximately 2,400
   people draw drinking water from private deep aquifer wells.  These wells lie within 3
   miles upgradientof hazardous substances on the base.
   site Responsibility:  This site is being addressed through
                     Federal actions.
                                 NPL LISTING HISTORY

                                 Proposed Date: 07/14/89
                                  Final Date: 02/21/90
                 Threats and Contaminants
               Contamination from trichtoroethylene (TCE), gasoline, oils, hydraulic fluid,
               ethylene glycol, and battery acid was found in shallow groundwater zones
               and soils. TCE was found in surface water samples at various locations.
               Contaminated groundwater, discharging to surface waters (Crow and
               Diamond Creeks), is believed to be the TCE contamination source. Direct
               contact with contaminated groundwater, surface water, and soil may
               adversely affect human health.
   March 1990
NPL HAZARDOUS WASTE SITES
               3
                                                                       continued

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                                                       F.E. WARREN AIR FORCE BASE
Cleanup Approach
  This site is being addressed in two stages: initial actions and a long-term remedial
  phase focusing on cleanup of the entire site.
  Response Action Status
            *  Initial Actions:  In 1986, the Air Force removed an acid disposal well
              system and an unknown amount of contaminated soil. In 1989, the Air
              Force removed a building drain sump, 3,000 gallons of contaminated liquid,
   300 gallons of contaminated sludge, and 300,000 pounds of contaminated soil from an
   area known as Spill Site 7.
              Entire Site: A Federal Facility Agreement is currently being negotiated
              that will define EPA and State involvement in future site investigations and
              cleanup actions. The Agreement will divide the site into seven cleanup
   stages. These consist of shallow and deep groundwater zones (two separate stages),
   the acid dry well area, the landfills, the fire training areas, the base firing range, and a
   munitions detonation area. The Agreement will also require further investigations at
   the site and provide a  time frame for submittal  of needed site documents. A draft
   report from a site investigation was completed  and reviewed by the EPA and the State.
   Further investigations  are needed to determine contamination in deeper groundwater
   zones. Also, the extent of potential or suspected surface sources needs to be further
   identified.  The Air Force is currently preparing  plans to conduct further site
   investigations at surface sources and to determine deeper groundwater contamination.

   Site Facts: F.E. Warren Air Force Base is participating in the Installation Restoration
   Program (IRP), a specially funded program developed in  1987 by the Department of
   Defense to identify, control, and investigate hazardous wastes on military or other DOD
   installations.
   Environmental Progress
   The initial actions to remove contaminated soil, sludge, and liquids have greatly reduced
   the potential for exposure to hazardous substances at the F.E. Warren Air Force Base
   site while further studies are taking place and cleanup activities are being planned.

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 MYSTERY
WYOMING
EPA ID# WYD98
Site Description
                                                              REGION 8
                                                       CONGRESSIONAL DIST. 01
                                                              Natrona County
                                                            1 mile east of Evansville

                                                                  Alias:
                                                                Brookhurst
   The 450-acre Mystery Bridge Road/Highway 20 site is located adjacent to an oil refinery
   and other industries in the Brookhurst and Mystery Bridge Subdivisions.  One area of
   the site, the KN Energy location, served as a natural gas processing operation. There
   was an unlined waste pond on this area that was used from 1965 until 1984. Another
   area of the site operated as an oil field service and includes a former toluene storage
   area, a truck wash drain system, and an abandoned sump. Studies started in 1986 in
   response to citizen complaints, identified the presence of volatile organic compounds
   (VOCs) in area wells and drinking water. The Brookhurst Subdivision was developed
   during the mid-1970s and consists of about 100 homes, 90 of which are affected by
   chlorinated  hydrocarbon contamination of drinking water wells. Domestic wells in the
   area tap into shallow groundwater.  In 1988, a contaminated groundwater plume was
   identified moving from the Little America Refining Co. (LARGO), an area  adjacent to the
   Brookhurst  property.
Site Responsibility: This site is being addressed through
                  Federal and potentially responsible
                  parties' actions.
                                                           NPL LISTING HISTORY

                                                           Proposed Date: 06/24/88
                  Threats and Contaminants
               Groundwater and soil are contaminated primarily with VOCs, petroleum
               products, and other hazardous substances. Drinking and making direct
               contact with contaminated groundwater is the greatest health threat to
               Brookhurst residents.
   March 1990
                       NPL HAZARDOUS WASTE SITES
continued

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                                                 MYSTERY BRIDGE ROAD/HIGHWAY 2Q
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 1987, the EPA provided bottled water to 45
              residences as an interim measure until the water distribution system was
              installed later in the year.  Hookups to the drinking water system between
  Evansville and Brookhurst were completed in 1988. A sedimentation pond and intake
  structure modifications were constructed at the Evansville water treatment plant.  In
  1988, KN Energy removed 35 drums of liquid and s/uc/gefrom the flare pit area and
  sent the drums off site to a disposal facility. KN Energy also installed a pump and treat
  system and soil vapor extraction system to eliminate the  release of contaminants into
  the groundwater.  In 1988, Dow Chemical Company and  Powell-Schlumberger
  removed 420 cubic yards of contaminated soil from the facility and installed a soil vapor
  extraction system to remove remaining contaminants in the soil.

             Entire Site: Dow, Dowell-Schlumberger, and KN Energy are conducting an
             investigation into the nature and extent of contamination at the site. Work
             performed during the investigation, including the installation of  13
  monitoring wells, soil vapor analysis, surface and sediment sampling, and collection of
  water samples from monitoring wells, was completed  in  1989.  The investigation is
  scheduled for completion in 1990.

  Site Facts: In 1988, the EPA issued three Consent Orders to three potentially
  responsible parties, KN Energy, Inc., Dow Chemical Co., and Dowell Schlumberger,
  Inc., ordering them to clean up two separate suspected sources of groundwater
  contamination and site contamination.  In 1988, the EPA  issued  an Administrative Order
  to LARCO, another potentially responsible party, requiring the company to investigate
  the contamination plume migrating toward the Brookhurst subdivision and to perform
  cleanup actions on its property and off site.
  Environmental Progress
  The immediate actions to provide bottled water until safe municipal water supplies
  could be provided, and to remove accessible surface contaminants have greatly
  reduced the potential for exposure to hazardous substances at the Mystery Bridge
  Road/Highway 20 site while studies and cleanup activities are being completed.

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       " his glossary defines the italicized terms used in the site
    J  ; fact sheets for the State of Wyoming. The terms and
      "  abbreviations contained in this glossary are often
defined in the context of hazardous waste management as de^
scribed in the site fact sheets, and apply specifically to work per-
formed under the Superfund program. Therefore, these terms
may have other meanings when used in a different context.

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
may possibly create toxic compounds 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 EPA
and the parties potentially responsible for site contamination. Under the terms of the
Order, the potentially responsible parties 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 respon-
sible 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 EPA direct-
ing the parties potentially responsible to perform site cleanups or studies (generally,
EPA does not issue unilateral orders for site studies).

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 pur-
poses. The water contained in the aquifer is called groundwater.

Consent Order:  [see Administrative Order on Consent].

Creosotes: Chemicals used in wood preserving operations and produced by distillation
of tar, including polycydic aromatic hydrocarbons and polynuclear aromatic hydrocar-
bons [see PAHs and PNAs]. Contaminating sediments, soils, and surface water, creo-
sotes may cause skin ulcerations and cancer with prolonged exposure.
                                       G-l

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   GLOSSARY;
Downgradienfc A downward hydrologic slope that causes groundwater to move
toward lower elevations. Therefore, wells downgradient of a contaminated groundwater
source are prone to receiving pollutants.

Installation Restoration Program: The specially funded program established in 1978
under which the Department of Defense has been identifying and evaluating its hazard-
ous waste sites and controlling the migration of hazardous contaminants from those
sites.

Intake: The source where a water supply is drawn from, such as from a river or water-
bed.

Landfill: A disposal facility where waste is placed in or on land.

Long-term Remedial Phase: Distinct, often incremental, steps that are taken to solve
site pollution problems. Depending on the complexity, site cleanup activities can be
separated into a number of these phases.

Migration: The movement of oil, gas, contaminants, water, or other liquids through
porous and permeable rock.

Pentachlorophenol (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.

Plume: A body of contaminated groundwater flowing from a specific source. The
movement 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 den-
sity of contaminants.

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 creosotes and can cause cancer.

Polynudear Aromatic Hydrocarbons (PNAs): PNAs, such as naphthalene, and biphen-
yls, are a group of highly reactive organic compounds that are a common component of
creosotes, which can be carcinogenic.

Potentially Responsible Parties (PRPs): Parties, including owners, who may have
contributed to the contamination at a Superfund site and may be liable for costs of
response actions. Parlies are considered PRPs until they admit liability or a court makes
a determination of liability. This means that PRPs may sign a consent decree or admin-
istrative order on consent [see Administrative Order on Consent] to participate in site
cleanup activity without admitting liability.
                                     G-2

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Sediment The layer of soil, sand and minerals at the bottom of surface waters, such as
streams, lakes, and rivers that absorb contaminants.

Seeps: Specific points where releases of liquid (usually leachate) form from waste
disposal areas, particularly along the lower edges of landfills.

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.

Sumps: A pit or tank that catches liquid runoff for drainage or disposal.

Trichloroethylene (TCE):  A stable, colorless liquid with a low boiling point. TCE has
many industrial applications, including use as 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 also Volatile Organic Compounds].

Upgradient: An upward slope; demarks areas that are higher than contaminated areas
and, therefore, are not prone to contamination by the movement of polluted groundwa-
ter.

Volatile Organic Compounds (VOCs): VOCs are made as secondary petrochemicals.
They include light alcohols, acetone, trichloroethylene, perchloroethylene, dichloroeth-
ylene, benzene, vinyl chloride, toluene, and methylene chloride. These potentially toxic
chemicals are used as solvents, 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.
                                      G-3

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xvEPA
 United States
 Environmental Protection
 Agency       ...-.-
 (OS-240)
 Washington, DC 20460

 Official Business
 Penally for Private Use
 $300

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