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FINDINGS AND RECOMMENDATIONS
EXTENT OF CONTAMINATION
Findings
Many marine s ites are known to contain sediments with high levels
of anthropogenic chemicals or to have altered biological
characteristics. However, there are no generally accepted definitions
of contamination that trigger consideration of remedial action. The
working definition of contaminated sediments used in this report is
those which contain chemical substances at concentrations that pose a
known or suspected environmental or human health threat. The sites
that require the most urgent attention are those reservoirs of
contamination that affect regions or that have the most severe impacts
on health and the environment. Pending revisions of the Superfund
Hazard Ranking System will facilitate the assessment and prioritization
of human health and ecological risks associated with contaminated
sediments.
Many contaminated marine sediments are located along all coasts of
the contiguous United States, both in local "hot spots" and distributed
over large areas. Some of these sites, but not many, have been well
characterized. Existing data on individual sites and their
contamination vary widely in content and organization. Assessments
using available data have been conducted on the national extent of
contamination and have identified a partial picture of the total
contaminated sediment problem. These studies have shown that a wide
variety of contaminants are found in sediments, including heavy metals,
polychlorinated biphenols (PCBs), DOT, and polynuclear aromatic
hydrocarbons (PAHs). However, no federal agency has assumed the full
responsibility of establishing a national inventory of sites with
contaminated sediments or a comprehensive assessment of the extent of
contamination on a national basis.
A number of state and federal agencies collect data for different
purposes and use different approaches. However, sediment contamination
data collected for one purpose may be of little relevance or
applicability for another because of parameters measured, methods used,
or temporal and spatial scales designated. For example, sediment data
assembled for setting regulatory criteria or for following national or
regional trends may be of little value in detecting site-specific
problems or in defining site-specific remediation requirements.
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5
This can be illustrated by N()AA's National Status and Trends
Program. As part of this program, NO M has acquired sediment data from
approximately 200 sites around the coasts of the United States (see
Robertson and O'Connor, pages 47-62~. This information is used to
determine broad national- and regional-scale status and trends in
sediment contamination levels. However, the network of stations is not
sufficiently dense to allow the data to be used to set clean-up
priorities or to make site-specific judgments. Indeed, the NOAA
program intentionally excluded from its database, sampling stations
deemed to be reflective of localized hot spots rather than of broad
regional contamination trends. In short, care should be exercised to
ensure that data generated by monitoring programs are not
inappropriately used beyond the limits or intent of the original
monitoring program.
At present, there are no generally accepted and validated sampling
techniques, testing protocols, or classification methodologies for
determining sediment contamination. A certain uniformity in parameters
measured and data reported is desirable to facilitate
intercomparisons. This must be accomplished by setting some national
standards, criteria, or guidelines.
In general, efforts by states to address potential marine sediment
contamination are diffuse and not well focused. For example, most
state water quality agencies focus on discharges and impacts to the
water column. Thus, little effort is being expended by state agencies
on identifying and remediating contaminated marine sites. State
hazardous waste agencies are, in most cases, directing their efforts to
upland areas so their involvement in marine sediments problems is
limited.
Recommendations
Search for Contaminated Sites
The location and extent of contaminated marine sediments have not
been comprehensively assessed on a national basis to identify
site-specific remediation targets. The federal government should
initiate such a program to delineate areas with contaminated sediment.
The objective should be neither detailed mapping nor duplication of
NOAA's regional National Status and Trends Program. In regions of
concern, or in areas of known hot spots, special attention should be
directed to identifying and characterizing specific contaminated
sites. The search for new sites or the reclassification of known sites
should proceed concurrently with remedial action.
Utilization of Federal, Regional, and Local Expertise
Due to the variability in environmental conditions among sites,
well-info``ued local specialists provide a critical complement to our
national expertise. Neither federal , regional, nor local managers can
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6
operate effectively in a vacuum. Managers at all levels of government
should interact and cooperate and remain receptive to the expertise and
concerns of other specialists in assessing or remediating contamination
at a particular site.
Coordination of Efforts
An interagency technical committee, including nongovernmental as
well as state and federal experts, should be established to evaluate
existing and emerging data on sediment contamination. This committee
would assemble data, prepare reports, and make recommendations as to
the need for and direction of sediment research and monitoring
activities, including sediment and sampling assessment methodologies.
The objective of the committee would be to focus the limited resources
on the most needed research and monitoring, reduce redundancy, and help
eliminate improper uses of data.
CLASSIFICATION METHODOLOGIES
Findings
A variety of biological and chemical sediment classification
methods are available. Individually or in combination, they attempt to
systematically characterize marine sediments with elevated levels of
contaminants, and correlate such concentration increases with adverse
biological effects. With one possible exception (the acute amphipod
bioassay), none of these techniques are routinely used and each has its
limitations. Indeed the cost and complexity of a number of these tests
virtually ensures that they will be used routinely only at large sites.
Several contaminated sediment classification techniques were
examined by the committee: sediment bioassays, sediment quality triad
approach, apparent effects threshold technique, and equilibrium
partitioning. Each technique is discussed in detail in a presented
symposium paper (in this volume) and some of the advantages and
disadvanges of each (for remedial action screening and sediment quality
criteria development) are set forth in Table 1.
From a remedial clean-up standpoint, the most useful sediment
testing and classification procedures would be those that are simple
and inexpensive, with rapidly available test results. If sediment
quality criteria methodologies are adopted by EPA, a routine basis for
establishing the presence of unacceptably high levels of sediment
contaminants may be available. The design and implementation of
remedial action for contaminated sediments are likely to be delayed and
frustrated unless one can readily determine "how clean is clean."
Development of an interim working methodology to establish such a
criterion would alleviate the delay.
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TABLE 1 Assessment of Sediment Classification Methodologies
Classification
method
Advantages
Disadvantages
Bioassay
Sediment Quality
Triad
· follows toxicologi-
cal methods developed
for water quality
criteria
· a direct measure of
sediment toxicity
· does not require
identification of
individual
contaminants
· does not assume a
specific route of
uptake
· acute results
available quickly
· established test
procedures in use for
dredged material
characterization
· based on a combina-
tion of laboratory and
field data indicating
effects of actual
contaminated sediments
· based on observed
biological effects
· does not assume a
specific route of
chemical uptake
· applicable to
complex mixtures
requires development of
standard chronic bioassay
methodologies
· may be more costly than
some chemical analyses
· difficult to translate
laboratory results to
natural conditions
· difficult to determine
chemical effects
· does not address human
health impacts
· results of chronic tests
may not be timely
· may not identify
causative contaminants
· limited by the
availability of existing
data or by the ability to
collect large amounts of
new data
· available data may be of
highly variable quality
· difficult to translate
laboratory results to
natural conditions
· does not address human
health impacts
· may not identify
causative contaminants
r
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8
TABLE 1 ( Continued)
Classif ication
methods
Advantages
Disadvantages
Sediment Quality
Triad (cons . ~
Apparent Effects
Threshold
· indicators are not
independent; c ovary with
grain size and organic
carbon content
· potentially not
comparable between
geographic locations
· does not consider
chemical bioavailability
from site to site
· uses existing data
(from field and
laboratory; e.g.,
Sediment Quality
Triad)
· applicable to all
chemicals and all
biological effects
· most useful for
prioritizing
contaminated areas
within a large site
· based on observed
biological effects
· does not assume a
specific route of
chemical uptake
· applicable to
complex mixtures
r
· limited by the
availability and quality of
existing data
· varies with choice of
biological effects
indicator
· relies on correlations/
may not identify causative
contaminants
· potentially not
comparable between
geographic locations
· may be both over- and
under-protective
difficult to translate
laboratory results to
natural conditions
· does not address human
health impacts
· multicompound
interactions not accounted
for
· Indicators are not
independent; c ovary with
grain size and organic
content
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9
TABLE 1 ~ Continued)
Classification
method
Advantages
Disadvantages
Equilibrium
Partitioning
· provides a chemical
specific criterion
· utilizes large
toxicological data
base incorporated in
water quality criteria
and other toxico-
logical endpoints
· relies on well-
developed partitioning
theory
· accounts for the
bioavailability of the
chemical interest
· provides a standard
basis for comparison
within and among sites
· where data are
available allows quick
and inexpensive
characterization
· incorporates a
built-in "how clean is
clean" standard
· is a direct measure-
ment of sediment
characteristics
· can be readily
incorporated into
existing regulatory
frameworks
~ does not consider complex
mixtures and chemical
interactions
~ currently limited to
hydrophobic neutral organic
compounds
· does not address human
health impacts
· limited to contaminants
for which both water
quality criteria (or other
suitable toxicological
endpoints) and sediment-
water partitioning
coefficients are available
0 relies on KoCa
measurements which are
often variable
· does not account for
contaminant uptake by
ingestion of particles or
direct absorption/
adsorption from sediments
· sediment and water may
not be at equilibrium with
respect to contaminant
concentration
· does not use toxico-
logical data derived from
the sediment of interest
· assumption of constant-
bioaccumulation factor for
various contaminants and
organisms is questionable
aKOc--carbon normalized sediment-water partition coefficient.
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10
Although a variety of methods for assessing contamination are
available, there is no single method that is widely accepted and~some
may be more suited to a particular situation than others. Approaches
that develop single numeric criteria often do not provide sufficient
data for assessing the overall significance of contamination at a
site. A number of approaches may be needed to evaluate the
significance and extent of contamination at any given site.
Recommendations
Improved Methodologies
In order to ensure that decision making is informed and
scientifically based, continued research and use of assessment
methodologies should provide information to determine
· a range of concentrations of chemicals in sediments that will
result in biological effects, and
· whether in-place sediments are causing biological impacts.
Additionally, increased efforts should be made to refine methods for
sediment classification to be used by regulatory agencies.
Tiered Testing
A tiered approach to the assessment of contaminated sediments
should be used. The approach would progress from relatively easy and
less expensive (but perhaps less definitive) tests to more sensitive
methods as needed.
RISKS TO HUMAN HEALTH AND THE ECOSYSTEM
Findings
The most significant human health risk associated with marine
sediment contamination may be ingestion of contaminated fish and
shellfish. Many compounds, such as some polyaromatic hydrocarbons
(PAHs), may be readily metabolized by enzymatic systems in higher
aquatic organisms such as fish, although there is uncertainty about
whether they are detoxified. Some invertebrates, such as bivalve
mollusks, have only a limited ability to metabolize PAHs and tend to
accumulate them to higher concentrations and retain them more.
Therefore, consumption of these animals may be a source of human
exposure. Trace metals are not degraded and may be bioaccumulated by
aquatic organisms and then transferred to humans via consumption of
seafood. Reports of "fin rot" and tumors in finfish, particularly
bottom-feeding fish in Puget Sound and the New York Bight in recent
years, provide further evidence that there may be substantial risk to
the ecosystem and potentially to human health due to the contamination
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in marine sediments. Although there is general consensus that seafoods
present a route of transfer of contaminants to humans from contaminated
sediments, the extent of risk that is posed is unknown.
In addition to the carcinogenic nature of many of these
contaminants, reproductive impairments and other sublethal effects in
humans are concerns that require increased attention. Risk assessments
of these latter endpoints have not been conducted. Furthermore,
inadequate attention has been given to mammalian studies of the
long-term chronic effects of ingesting contaminated fish and
shellfish. Epidemiological studies of human populations living near
contaminated sediment sites also have been under-emphasized.
Assessment of the ecological effects resulting from sediment
contamination is an area that needs additional study. This is
especially true for soft-bottom communities in trying to correlate
ecological impacts with chemical- specific factors . Accumulation of
contaminants in marine sediments can cause death, reproductive failure,
growth impairment, or other detrimental changes in the organisms
exposed to these contaminants. Such changes can impact not only
individuals but also entire benthic populations and communities.
Both localized and widespread contamination has in the past
resulted in significant population and community changes. Typically
this involves the elimination of less tolerant species and an increase
in more tolerant species. Such changes can have far reaching,
long-term effects on a given ecosystem. Generally, those species that
are eliminated have not received the attention they deserve in the
assessment of ecological effects. Furthermore, the technical
capability has not evolved for interpreting population and community
responses in relation to specific chemicals.
Sublethal and chronic effects of contaminants on the marine
ecosystem are a significant environmental concern. However, at the
present time there are no widely accepted sublethal and/or chronic
effects tests available. Much research is being conducted on tests for
growth, reproduction, or biological abnormalities . Interpretation of
such tests is often difficult and there are few established criteria
available to j udge the sublethal and chronic effects of contaminants on
the marine ecosystem.
Recommendations
Assessment of Risk Due to Contamination
Although the assessment of human health risk is important, a more
balanced approach requires greater emphasis on ecosystem impacts. This
will require regulatory agencies to utilize new assays being developed
to detect and gauge the effect of contamination on physiology (assays
such as immune suppress ion, enzyme induction, and DNA adduct
formation), life stage impacts (using parameters such as reproductive
success, growth, and recruitment), pathological effects, and changes in
community structure.
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12
In terms of risks to human health, consideration should be given to
conducting available retrospective human epidemiology studies of
exposed populations in the development of an overall assessment and
remedial plan.
MOBILIZATION AND RESUSPENSION OF CONTAMINANTS
Findings
The decision to manage contaminated marine sediments in place or to
remove and relocate them on land involves consideration of the
potential for contaminant mobilization and release to the environment.
There is a tendency for heavy metals in marine sediments placed in
on-land disposal sites to desorb under changing geochemical conditions
(such as decreased pH due to acid formation) and potentially allow
chemicals to leach into groundwater. Organic chemicals found in marine
sediments tend to maintain relatively constant solubility and mobility
potential when disposed of on land. When contaminated sediments are
excavated and placed in contact with the air, relatively low
concentrations of volatile organics can contaminate the air. The most
obvious difference in risks associated with on-land and aquatic
disposal of contaminated marine sediments is the greater significance
of food chain contamination as an exposure pathway in aquatic disposal.
Estimates of both deposition rates and erosion rates are needed in
order to decide whether to remove contaminated sediments. If natural
sedimentation causes the rapid burial of contaminated sediments in
place, then other remediation may not be needed. However, if the
contaminated sediment is subject to resuspension and dispersion,
in-place capping or removal may be necessary, even if the contamination
is distributed over large areas or long distances.
Where the environmental impact potential is severe (e.g.,
downstream shellfish beds or drinking water intakes) a significant
erosion or resuspension potential may suggest the need for quick
remedial or removal action while sediment contaminants are still
relatively localized and concentrated.
Our understanding of the transport of coarse-grained, noncohesive
sediments is relatively well developed. Unfortunately, contaminants
are most often associated with fine-grained cohesive sediments and the
ability to forecast their behavior with confidence is very poor.
Significant research is under way by the Army Corps of Engineers and
the Environmental Protection Agency to try to define the sediment-water
boundary layer conditions that limit the use of predictive models.
With information concerning the strength of the currents, some general
statements can be made concerning whether a site is likely to be one of
scour or of deposition. However, the rates of either erosion or
deposition cannot now be estimated from measured parameters. General
statements are usually not an adequate basis for management decisions.
A more complete understanding of the sediment transport processes for
fine-grained cohesive sediments is needed.
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Present practice, based on state-of-the-art knowledge, is to employ
empirical models. For example, several major studies have been
conducted by the Corps of Engineers for Mississippi Sound in the Gulf
of Mexico, Los Angeles and Long Beach harbors, and Chesapeake Bay.
These investigations have attempted to modify and adapt
three-dimensional models to site- specific conditions. Resuspension
rate, settling velocity, deposition rate, critical erosion velocity,
rate of consolidation, rate of biological mixing, and other variables
must be empirically determined for each site. The relevant processes
are described by direct measurements in the field to determine a set of
empirical parameters that are then applied to the site. Measured
site- specific data then provide the quantitative examples that are
assumed to be typical of that site at all times. Although the models
rely on highly empirical approaches, they are the best tools presently
available for making predictions of sediment resuspension and
transport.
Empirical models for predicting the resuspension and mixing of
contaminated sediments have serious limitations which include the
following:
1. Relying on measurements made at a specific time and place under
a particular set of conditions. There is no guarantee that the
measured rates will be accurate if any of the conditions
change. Small changes in the environment can lead to very large
discrepancies between the empirical forecast and the actual
phenomenon. As a result, the empirical models are accompanied
by potentially large, and usually, unspecified uncertainties.
In many cases, the magnitude of the uncertainties may be
acceptable in the management decision if it is known with
confidence.
2. Development of empirical models can be extremely costly. There
are many types of data needed and the measurements have to be
made at many locations over long time periods to improve
confidence in the results . Additionally, measurements have to
be made for every s ite of interest. This would not be a serious
disadvantage if there were only a few contaminated sites.
Unfortunately, there are many sites that need attention.
Recommendations
Contaminant Transport and Partitioning
Continued and expanded support should be given to understanding the
partitioning of contaminants among sediments, soils, water, organisms,
and the atmosphere, as well as the transport of substances in the
various phases.
In
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Research in Sediment Transport
To keep costs of modeling fine-grained sediment transport
reasonable, models built on basic processes need to be developed.
While empirical models continue to be used to reach management
decisions, effort should be simultaneously directed to understanding
the basic processes to be modeled and the validation of models in the
field. Specifically, support should be expanded for research to
determine the fundamental processes responsible for sediment cohesion
and the factors controlling their resuspension. There is also a need
to improve the reliability of estimates of both deposition and
resuspension. Research programs in this area should be expanded and
diversified.
Tiered Response Strategy
A tiered strategy is needed to address contaminated sediment
problems in situations in which high erosion rates or resuspension
potential may rapidly alter the distribution of contaminants and there
is no time to carry out more detailed assessments. Problems in
high-energy environments should be assessed promptly.
CONTAMINATED SEDIMENT MANAGEMENT STRATEGIES
Findings
Although the dredged material management strategy developed by the
Corps of Engineers may be relevant to severely contaminated sediments,
it is important from a management standpoint to differentiate them from
less contaminanted sediments. In particular, most highly sophisticated
remedial technologies (i.e., those involving treatment or destruction
of associated contaminants) are likely to be cost-effective only in
small areas and for sediments with relatively high contamination
levels. Sediment contamination problems often involve large volumes of
sediment with relatively low contamination levels. As a result, some
highly sophisticated technologies may be inapplicable or inefficient
for remediating contaminated sediments.
"No action" may be the preferred alternative in cases in which the
remedy may be worse than the disease--e."., where dredging or
stabilizing contaminated sediments results in more biological damage
than leaving the material in place. Contaminants generally accumulate
in depositional zones, and, if the source is controlled, new sediments
will deposit and cap the contaminated material over time. In effect,
no action alternatives in such cases may result in natural capping.
Extensive preremediation studies, as practiced at very large sites
(e.g., Commencement Bay, New Bedford Harbor, upper Hudson River) may
not be practical at much smaller sites. Routine screening procedures
and validated sediment assessment methods may be especially valuable in
such cases. Large-scale remedial technologies are often not applicable
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to small sites for a variety of reasons. In such cases, regional sites
or facilities may provide a means for handling sediments from several
smaller s ites .
There are existing management alternatives that have been
effectively used for dealing with contaminated sites.
1. No action may be an acceptable option if the contamination
degrades or is buried by natural deposition of clean sediment in
a short period of time.
2. In-place capping may be a useful option if the sediments are not
in a navigation channel or if groundwater is not flowing through
the site.
3. Removal and subaqueous burial off-site may be a viable option,
although the experience with this technique is limited to
relatively shallow water (< 100 ft).
Incineration seems to be viable only for sites with relatively
small amounts of sediments containing high concentrations of
combustible contaminants.
. Other techniques to assist in remediation of contaminated
sediment may be appropriate in special cases. Examples include
a variety of sediment stabilization or solidification
techniques, and biological and/or chemical treatment.
Recommendations
Dredged Material Management Strategy
Additional evaluation should be conducted to determine the
applicability of the Corps of Engineers' dredged material management
strategy to more severely contaminated sediments.
No Action
No action should always be considered as an alternative strategy
for minimizing biological damage. In using the no-action strategy as a
form of natural capping of contaminated material, consideration should
be given to the length of time it takes for contaminants to be isolated
from the food chain.
REMEDIAL TECHNOLOGIES
Findings
From a remediation standpoint, the most important factors are
likely to be defining of the clean-up targets technical and cost
feasibility, natural recovery estimates, and ability to distinguish
and/or control continuing sources of contaminants.
Dredging technology exists that is capable of greatly reducing
turbidity and resuspension in connection with dredging of bottom
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sediments in most applications. However, because of legal (i.e., Jones
Act) and practical restrictions that limit access to foreign-built
vessels domestically, it may be difficult to secure access to this
technology in the United States--except as equipment fitted onto
U.S.-built vessels or supplied through U.S. subsidiaries of foreign
dredging companies. U.S. government policies have not provided
adequate encouragement to domestic firms to construct innovative
dredges.
Although silt curtains can prevent movement of sediment in the top
two or three feet of water column, they allow movement of sediment
under the silt curtain. Silt curtains cannot operate with currents
faster than one knot and are ineffective in waves. Thus, the use of
the silt curtains is confined to low-energy areas.
Capping of contaminated sediments--whether in place, as mounds, or
in subaqueous pits--in many cases offers a promising means of
effectively isolating and containing associated contaminants. A
potentially significant legal and policy issue is whether capping with
clean sediments is to be deemed a preferred treatment approach under
SARA, Section 121(b). On the one hand, capping can be done on site
(which is favored over offsite transport) and it can "significantly
reduce the . . . mobility of the hazardous substances, pollutants, and
contaminants" present. On the other hand, it is not treatment in the
usual chemical, biological, or physical sense, but rather containment
or permanent storage. If capping materials are modified with the
addition of carbon or other materials they may sorb contaminants and
thus could more reasonably be defined as a treatment alternative.
While widely applicable, there are practical limits to the
feasibility of capping. Among the factors that may preclude or
constrain the use of capping are water depth; low sediment density;
high sediment water content; active erosional area; active navigational
channel requiring periodic maintenance dredging; and the use of trawls,
draglines, or oyster dredges, which would destroy the integrity of the
cap. Although the sediment properties needed for an effective cap are
not well-defined, both clay and sand have been used successfully.
Attention must also be paid to any subsequent disturbance of the cap
either by natural processes (e.g., storm erosion or bioturbation) or
human activity (e.g., fishing).
There are several examples of capping of dredged sediment mounds on
subaqueous disposal sites. These provide very useful experience for
guiding future decisions. There are, however, few general standard
criteria for evaluating the likely success of a planned capping
operation. Where capping is clearly feasible, prudence (and/or SARA)
may dictate well-directed monitoring. Such monitoring can constitute a
significant proportion of the total remedial action cost.
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Recommendations
Source Control
Source control measures must be cons idered in all cases, including
no action. Federal and state regulatory agencies requiring remedial
action should implement source control measures as a component of
remedial action when applicable and appropriate. Use of financial
incentives through strict liability for assessment costs, remedial
actions, and damages also may play an important role in source control,
provided that trustees make aggressive efforts to hold responsible
parties liable for releases into the environment.
Technology and Information Transfer
Aggressive technology and information transfer mechanisms are
needed to ensure that knowledge gained and lessons learned from all
remedial actions are available and accessible to managers confronting
new remediation problems at federal, regional, and local levels.
Knowledge gained should be systematically compiled in guidance
documents. Lessons learned regarding the feasibility of sophisticated
remedial technologies under varying conditions of contamination
severity and extent should be documented and made widely available to
facilitate future decision making. Lastly, experience gained through
the use of screening procedures at large sites should be distilled and
generalized into routine methodologies for economically assessing
smaller sites.
Remediation and Navigational Dredging
When possible, remediation projects should be designed to take
advantage of existing navigational dredging activities that may already
be authorized in conjunction with the Clean Water Act, Section 115 or
Section 10/404.
Remedial Technologies
Research and development should be encouraged by the federal
government to develop technology and equipment for efficiently removing
contaminated sediments and to make it available in the United States.
Foreign technologies should continue to be examined relative to their
appropriateness in this country. Efforts to conduct and fund research
and development as a partnership between government and industry should
be encouraged.
Use of Capping
Although capping might not, in the strictest terms, be considered a
remedial technology, it should not be ignored because it can play a
valuable role in remediating contaminated sites.
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Well-focused Monitoring
Monitoring programs should be well-focused on testing forecasts
made during design of the remediation plan. To the extent possible,
monitoring should be extended to remove uncertainties in the basic
understanding of contaminated sediment behavior. For example,
monitoring of capped areas might focus on changes of cap thickness,
erosion around boundaries, and leakage of contaminants through the cap.
REMEDIATION AND SOURCE CONTROL: ECONOMIC CONSIDERATIONS
Findings
Remedial actions are costly and become more expensive as additional
levels of clean-up or treatment are pursued. The role of tradeoffs
between possible technologies at and among sites must be considered,
given the scarcity of funds to clean up contaminated sites and the
potentially great number of sites.
The use of benefit-cost analysis as part of the remedial action
decision process would provide perspective on the issues involved. It
would place investments in this area on the same footing as other
public investments. However, difficulty in quantifying benefits from
remedial actions in monetary terms makes reliance on benefit-cost
analysis infeasible in a number of cases. Nonetheless, in light of the
high cost of remedial actions, it is important that implicit (if not
explicit) consideration be given to potential benefits before remedial
actions are undertaken.
Cost-effectiveness analysis is also a valuable technique for
helping to guide clean-up efforts at and among sites when a decision to
remediate has been made. However, to be applied correctly, both short-
and long-term costs must be included, and costs must be estimated
consistently for alternative actions at and among sites.
The process of assessing the need for remediation and evaluating
alternative remedial actions for a site appears to be excessively long
and costly. In many cases, millions of dollars and several years are
expended before a decision is made. If remedial action is excessively
delayed, benefits may diminish over time.
Removal of contaminated sediments can be very expensive, varying
widely from several hundred thousand dollars to tens of millions of
dollars. Data on 15 clean-up sites indicate that total clean-up costs
can reach $500,000 to $1,000,000 per acre. This compares with
iFor purposes of comparison, assume that a one-acre cleanup involved
removing overburden to a depth of one yard, or a total of 43,560 yds3
of contaminated material. In that event, total cleanup costs would range
from $11.50 to $23.00 per yd3.
2U.S. Congress Office of Technology Assessment . 1988 . Are we cleaning
up? 10 Superfund case studies. Special Report OTA-ITE-362. Washington,
D.C.: U.S. Government Printing Office.
OCR for page 19
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an average unit cost of navigation dredging of $1 to $2 per cubic yard
of sediment dredged. The average unit cost of all dredging, both
government and private, is estimated at $1.67 per cubic yard of
material dredged. 3 Onsite incineration, one of the remedial measures
proposed at various sites, is also very expensive. The estimates
quoted are from $186 to $750 per cubic yard. 4
Recommendations
Use of Benefit-Cost Comparisons
In view of the high cost of remedial actions in most cases, greater
use should be made of benefit-cost comparisons over ecologically
relevant time periods in order to place investments in this area on the
same economic footing as investments in other public proj ects .
Cost-Effectiveness Analysis
Cost-effectiveness analysis of alternative remedial actions should
consider both short- and long-term costs. Comparisons at and among
sites should be based on costs estimated using a consistent approach.
Degree of Remediation
In evaluating the degree of remediation to be conducted at a site,
it should be recognized that incremental costs typically will increase
rapidly as additional levels of clean-up are sought.
Economic and Environmental Cons iterations
The decision as to whether or not remedial actions are undertaken
should be based on a balanced comparison of the anticipated
environmental and public health benefits of actions with their costs,
including possible environmental and health risks.
Infeasible Remedial Options
Clearly infeasible options should be eliminated at the outset,
before alternative remedial actions are considered in depth.
3Pequegnat, W.E. 1987. Relationship between dredged material and
toxicity. TERRA et AQUA 34.
40p. cit., no. 1.
Representative terms from entire chapter:
remedial actions
