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Final Report: Evaluation of Placement and Effectiveness of Sediment Caps
EPA Grant Number: R825513C009Subproject: this is subproject number 009 , established and managed by the Center Director under grant R825513
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: HSRC (1989) - South and Southwest HSRC
Center Director: D. Reible, Danny
Title: Evaluation of Placement and Effectiveness of Sediment Caps
Investigators: D. Reible, Danny , Thibodeaux, Louis J. , Valsaraj, Kalliat T.
Institution: Louisiana State University - Baton Rouge
EPA Project Officer: Manty, Dale
Project Period: January 1, 1995 through January 1, 1997
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (1989)
Research Category: Hazardous Substance Research Centers
Description:
Objective:The project had the overall objective of evaluating and overcoming certain potential limitations of capping in the areas of cap placement technologies and long-term cap containment effectiveness. The specific objectives are outlined below.
Cap Placement Technology
The objectives of this portion of the
effort was improved guidance on the selection of cap placement technologies and
model tools for the evaluation of contaminant losses that occur during cap
placement and during subsequent cap consolidation. Cap placement techniques
evaluated include point dumping from the water surface, application with a
diffuser near the sediment-water interface, and sediment broadcasting. The need
for and the effectiveness of geotextile placement prior to cap placement was
also assessed. Post-placement consolidation and the resulting contaminant losses
were also evaluated and compared to laboratory consolidation measurements and
the predictions of mathematical models.
Long-Term Containment by a Cap
The objective of this portion of the
effort was to evaluate loss of containment caused by advection and random
penetrations or localized cap failures. Potentially important advective
processes include porewater expression during consolidation, groundwater
seepage, and gas migration.
The laboratory experiments were used to evaluate the mobility of several contaminants in physical models of capping systems. The research for this project employs primarily Baton Rouge area freshwater sediments inoculated with pyrene, phenanthrene, and dibenzofuran. Inoculated sediments are necessary to control contaminant fluxes within detectable ranges and generally provide a conservative estimate of cap containment in that contaminant mobility is likely enhanced by the required sediment processing. The inoculated compounds exhibited a range of hydrophobicities and mobilities (log octanol-water partition coefficients were 5, 4.5 and 4, respectively). Recognizing that differences in contaminant mobility are often noted between aged and freshly contaminated sediments, experiments were conducted with field contaminated sediments. Rouge River, Michigan sediments were acquired to evaluate these effects. The sediment contained significant levels of various PAHs including pyrene, and phenanthrene at levels similar to our inoculated sediments. The sediment also had oil and grease content of about 4% which could significantly effect the mobility of the contaminants.
Due to the slow time scale of migration through a cap, model development and
validation was limited to experiments with sediments inoculated with toluene.
This much less hydrophobic compound allowed migration rates that were
sufficiently fast to allow experiments over a period of weeks to month to get
measurable movement of the contaminant.
Cap Placement
Technology
A bench scale laboratory facility with sediment surface area
of 1.7 m2 was constructed to evaluate cap placement techniques and the
mechanisms and rates of contaminant loss from the underlying sediments during
placement. Cap placement was via near bottom placement, near-surface release and
mechanically.
Long-Term Containment by a Cap
Containment losses by advective
processes and localized cap failures were evaluated in bench scale laboratory
experiments using the facility mentioned above. Laboratory experiments were used
to develop criteria which identify significant losses from possible penetrations
of the cap and to test and extend models of this process.
Cap Placement
The limitations of laboratory testing of cap
placement are readily apparent. Only a limited range of cap and sediment
materials and cap placement technologies could be evaluated. In addition, the
limited size of the system meant that far-field cap or sediment resuspension
losses could not be assessed.
Experiments indicated, however, that it was possible to place relatively dense (sand) caps by simple release from the near-surface and allowing to settle by gravity alone. Sharp separation was noted between the cap and the underlying sediment, even in relatively soft sediments (specific gravity about 0.75).
Long-Term Containment by a Cap
Processes that may lead to excessive
contaminant migration through a cap include advection, especially during the
initial period of cap consolidation, and diffusion. Both processes are retarded
by sorption in the cap. Oil and grease was also found to influence partitioning
of contaminants in the cap by providing a strong sink for hydrophobic compounds.
Migration of the oil and grease phase could greatly enhance migration of the
contaminants. Entrapment of the oil and grease phase by a capillary barrier,
however, could dramatically decrease contaminant migration. In some cases,
sealing of a sediment surface layer with oil and grease held at the interface by
capillary forces seemed to decrease contaminant flux over that expected by
partitioning into that oil and grease phase.
Consolidation of the sediment underlying a cap was found to be adequately modeled by the Corps of Engineers model PCDDF. This model has been proposed for subaqueous consolidation processes although its primary application has been to consolidation of exposed dredged material. The chemical migration during the consolidation process was adequately described by the porewater extrusion divided by the effective retardation factor of the contaminant due to sorption.
The contaminant migration after the completion of consolidation was adequately described by the model presented by Reible in the EPA/ARCs guidance document for in-situ sediment capping (Palermo, M.R., S. Maynord, J. Miller and D.D. Reible, "Guidance for In-Situ Subaqueous Capping of Contaminated Sediments", Assessment and Remediation of Contaminated Sediments (ARCS) Program, Great Lakes National Program Office, US EPA 905-B96-004 ). The model assumes that consolidation is effectively instantaneous and that subsequent migration occurs via advection and diffusion. The model was also described in Myers, T.E., M.R. Palermo, T.J. Olin, D.E. Averett, D.D. Reible, J.L. Martin, S.C. McCutcheon, "Estimating Contaminant Losses from Components fo Remediation Alternatives for Contaminated Sediments," Final Report prepared for the US Environmental Protection Agency, Great Lakes National Program Office, Chicago, IL, 1996.
Summary of Results:
Journal Articles on this Report: 5 Displayed | Download in RIS Format
| Other subproject views: | All 19 publications | 7 publications in selected types | All 5 journal articles |
| Other center views: | All 427 publications | 162 publications in selected types | All 114 journal articles |
| Type | Citation | ||
|---|---|---|---|
|
|
Reible DD, Thibodeaux LJ, Valsaraj KT. Capping contaminated sediments in situ. Centerpoint 1995;2(2):12-13. |
R825513C009 (Final) |
not available |
|
|
Reible DD, Thibodeaux LJ, Valsaraj KT. Capping helps nature clean contaminated sediments. Centerpoint 1996;3(1):1-3. |
R825513C009 (Final) |
not available |
|
|
Thoma GJ, Reible DD, Valsaraj KT, Thibodeaux LJ. Efficiency of capping contaminated sediments in situ. 2. Mathematics of diffusion-adsorption in the capping layer. Environmental Science & Technology 1993:27(12):2412-2419. |
R825513C009 (Final) |
not available |
|
|
Valsaraj KT, Verma S, Sojitra I, Reible DD, Thibodeaux LJ. Diffusive transport of organic colloids from sediment beds. Journal of Environmental Engineering 1993;122(8):722-729. |
R825513C008 (Final) R825513C009 (Final) |
not available |
|
|
Valsaraj KT, Thoma GJ, Porter CL, Reible DD, Thibodeaux LJ. Transport of dissolved organic carbon-derived natural colloids from bed sediments to overlying water: Laboratory simulations. Water Science and Technology 1993;28(8-9):139-147. |
R825513C008 (Final) R825513C009 (Final) |
not available |
transport processes, contaminant modeling, and contaminant flux. , Ecosystem Protection/Environmental Exposure & Risk, Water, Geographic Area, Scientific Discipline, Waste, RFA, Chemical Engineering, Analytical Chemistry, Hazardous Waste, Environmental Engineering, EPA Region, Fate & Transport, Environmental Chemistry, Contaminated Sediments, Hazardous, Ecology and Ecosystems, heavy metals, remediation, risk assessment, contaminant transport models, sediment caps, biodegradation, biotransformation, fate and transport, extraction of metals, soil and groundwater remediation, control technologies, furans, technical outreach, chemical kinetics, contaminated sediment, environmental technology, CERCLA, hazardous waste management, marine sediments, region 4, contaminated soil, bioremediation, contaminated marine sediment, hazardous waste treatment, PAH, sediment treatment, technology transfer, leaching
Progress and Final Reports:
Original Abstract
Main Center Abstract and Reports:
R825513 HSRC (1989) - South and Southwest HSRC
Subprojects under this Center:
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R825513C001 Sediment Resuspension and Contaminant Transport in an Estuary.
R825513C002 Contaminant Transport Across Cohesive Sediment Interfaces.
R825513C003 Mobilization and Fate of Inorganic Contaminant due to Resuspension of Cohesive Sediment.
R825513C004 Source Identification, Transformation, and Transport Processes of N-, O- and S- Containing Organic Chemicals in Wetland and Upland Sediments.
R825513C005 Mobility and Transport of Radium from Sediment and Waste Pits.
R825513C006 Anaerobic Biodegradation of 2,4,6-Trinitrotoluene and Other Nitroaromatic Compounds by Clostridium Acetobutylicum.
R825513C007 Investigation on the Fate and Biotransformation of Hexachlorobutadiene and Chlorobenzenes in a Sediment-Water Estuarine System
R825513C008 An Investigation of Chemical Transport from Contaminated Sediments through Porous Containment Structures
R825513C009 Evaluation of Placement and Effectiveness of Sediment Caps
R825513C010 Coupled Biological and Physicochemical Bed-Sediment Processes
R825513C011 Pollutant Fluxes to Aquatic Systems via Coupled Biological and Physicochemical Bed-Sediment Processes
R825513C012 Controls on Metals Partitioning in Contaminated Sediments
R825513C013 Phytoremediation of TNT Contaminated Soil and Groundwaters
R825513C014 Sediment-Based Remediation of Hazardous Substances at a Contaminated Military Base
R825513C015 Effect of Natural Dynamic Changes on Pollutant-Sediment Interaction
R825513C016 Desorption of Nonpolar Organic Pollutants from Historically Contaminated Sediments and Dredged Materials
R825513C017 Modeling Air Emissions of Organic Compounds from Contaminated Sediments and Dredged Materials title change in last year to "Long-term Release of Pollutants from Contaminated Sediment Dredged Material"
R825513C018 Development of an Integrated Optic Interferometer for In-Situ Monitoring of Volatile Hydrocarbons
R825513C019 Bioremediation of Contaminated Sediments and Dredged Material
R825513C020 Bioremediation of Sediments Contaminated with Polyaromatic Hydrocarbons
R825513C021 Role of Particles in Mobilizing Hazardous Chemicals in Urban Runoff
R825513C022 Particle Transport and Deposit Morphology at the Sediment/Water Interface
R825513C023 Uptake of Metal Ions from Aqueous Solutions by Sediments
R825513C024 Bioavailability of Desorption Resistant Hydrocarbons in Sediment-Water Systems.
R825513C025 Interactive Roles of Microbial and Spartina Populations in Mercury Methylation Processes in Bioremediation of Contaminated Sediments in Salt-Marsh Systems
R825513C026 Evaluation of Physical-Chemical Methods for Rapid Assessment of the Bioavailability of Moderately Polar Compounds in Sediments
R825513C027 Freshwater Bioturbators in Riverine Sediments as Enhancers of Contaminant Release
R825513C028 Characterization of Laguna Madre Contaminated Sediments.
R825513C029 The Role of Competitive Adsorption of Suspended Sediments in Determining Partitioning and Colloidal Stability.
R825513C030 Remediation of TNT-Contaminated Soil by Cyanobacterial Mat.
R825513C031 Experimental and Detailed Mathematical Modeling of Diffusion of Contaminants in Fluids
R825513C033 Application of Biotechnology in Bioremediation of Contaminated Sediments
R825513C034 Characterization of PAH's Degrading Bacteria in Coastal Sediments
R825513C035 Dynamic Aspects of Metal Speciation in the Miami River Sediments in Relation to Particle Size Distribution of Chemical Heterogeneity