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Assessment and Remediation of Contaminated Sediments (ARCS) Program

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Final Report

Prepared by
US Army Engineer District, Buffalo

For the
Assessment and Remediation of Contaminated Sediments (ARCS) Program
U.S. Environmental Protection Agency
Great Lakes National Program Office - Chicago, Illinois

Source: US Army Engineer District. 1993. Abstract and Table of Contents to "Pilot-Scale Demonstration of Thermal Desorption for the Treatment of Buffalo River Sediments," EPA-905-R93-005. Chicago, Ill.: U.S. Environmental Protection Agency

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Pilot-Scale Demonstration of Thermal Desorption for the Treatment of Buffalo River Sediments


This report presents the results of a pilot scale demonstration to remediate contaminated sediments from the Buffalo River. A thermal desorption unit was evaluated for its effectiveness in remediating Buffalo River sediments contaminated with polycyclic aromatic hydrocarbons (PAHs). Sediments were processed at various water contents, thermal unit residence times, and temperatures to evaluate the effect of these process variables on treatment efficiency and materials handling. A portion of the residual solids from the thermal treatment process was mixed with various proportions of Portland cement to evaluate the ability of one solidification/stabilization process to bind metal contaminants.

With sediments remaining in the thermal desorption unit from 30 to 90 minutes and sediment temperatures reaching 300 to 480deg.F; 43.2 to 97.9 percent of total PAHs were removed while 9.1 to 100 percent of total PCBs (Aroclors 1248 and 1254) were removed. Although this thermal process had little effect on most metals, 16.7 to 100 percent of mercury was removed from sediments during processing. Removal rates for constituents of concern did not correlate well with treatment times or temperatures.

This paper has been reviewed in accordance with the U.S. Environmental Protection Agency's peer and administrative review policies and approved for presentation and publication.

Table of Contents


    • 2.1 Technology Selection
    • 2.2 Planning Document
    • 2.3 Environmental Assessment
    • 2.4 Scope of Work/Contract
    • 2.5 Sample Location and Excavation
    • 2.6 Site Description
      • 2.6.1 Site Preparation
    • 2.7 Material Handling
      • 2.7.1 Transport
      • 2.7.2 Screening
      • 2.7.3 Storage
      • 2.7.4 Addition of Water
      • 2.7.5 Feed Operations
    • 2.8 Thermal Desorption
      • 2.8.1 System Description
        1. Material Handling
        2. Thermal Processor
        3. Media Heater
        4. Off-Gas Control
      • 2.8.2 Pilot Scale Demonstration
        1. Sediment A
        2. Sediment B
        3. Sediment C
        4. Sediment D
    • 2.9 Residuals Management
    • 2.10 Solidification of Solid Residue
    • 2.11 Execution and Costs
    • 2.12 Monitoring
      • 2.12.1 Process Monitoring by Remediation Technologies, Inc. (RETEC)
      • 2.12.2 Air Monitoring
        1. Air Monitoring by Remediation Technologies, Inc. (RETEC)
        2. Air Monitoring by E-Three, Inc.
      • 2.12.3 Corps of Engineers Monitoring
        1. Sampling
        2. Analytical Protocol
    • 3.1 Corps of Engineers Results
      • 3.1.1 Overall Mass Balance
      • 3.1.2 Solids Content
      • 3.1.3 Metals
      • 3.1.4 Polycyclic Aromatic Hydrocarbons (PAHs)
      • 3.1.5 Solvent Extractables (SE)
      • 3.1.6 Total Organic Carbon (TOC)
      • 3.1.7 Polychlorinated Biphenyls (PCB)
      • 3.1.8 Solidification/Stabilization of Treated Residue
    • 3.2 Full Scale Implementation
      • 3.2.1 Thermal Desorption Remediation
        1. Full-Scale Treatment System
        2. Cost Estimate for Sediment Remediation
    • 3.3 Conclusions and Recommendations
      • 3.3.1 Conclusions
      • 3.3.2 Recommendations/Lessons Learned

APPENDIX A: Sample Calculations
APPENDIX B: Unreduced Analytical Data


The 1987 amendments to the Clean Water Act, Section 118(c)(3), authorized the United States Environmental Protection Agency's (USEPA) Great Lakes National Program Office (GLNPO) to conduct a 5-year study and demonstration project on the control and removal of toxic pollutants in the Great Lakes, with emphasis on the removal of toxic pollutants from bottom sediments (U.S. Environmental Protection Agency, 1990). The Great Lakes Water Quality Board of the International Joint Commission (IJC) identified 43 Areas of Concern (AOC) in the Great Lakes Basin where one or more of the objectives of the 1978 Great Lakes Water Quality Agreement and other jurisdictional standards, criteria, or guidelines are exceeded. GLNPO initiated the Assessment and Remediation of Contaminated Sediments (ARCS) Program to assess the nature and extent of bottom sediment contamination at the selected AOCs, evaluate and demonstrate remedial options, and provide guidance on the assessment of contaminated sediment problems and the selection and implementation of necessary remedial actions in the AOCs and other locations in the Great Lakes. The Buffalo River AOC, Buffalo, New York, was one area specified in the Clean Water Act as requiring priority consideration in locating and conducting on-site demonstration projects.

Past industrial and municipal discharges to the Buffalo River have polluted the river and its sediments. As a result, the river exhibits environmental degradation and impairment of beneficial uses of water and biota (New York State DEC, 1989). A pilot-scale demonstration was conducted in Buffalo, New York in the fall of 1991 to evaluate the ability of a thermal desorption process to remediate Buffalo River sediments contaminated with polynuclear aromatic hydrocarbons (PAHs).


The objective of the Buffalo River pilot scale treatment technology demonstration was to evaluate thermal desorption as a treatment technology for sediments from the Buffalo River Area of Concern. Specific objectives of the pilot-scale demonstration included determining: the thermal desorption process' efficiencies in removing organic contaminants from sediments; the operating parameters that affect the removal efficiencies; the equipment necessary to achieve those removal efficiencies; the pretreatment handling and processing requirements of the sediments; and the characteristics of each of the process residual streams and the proper method of disposal for each residual. Another objective of the demonstration was to provide technology-specific information to be used in the development of cost estimates for full scale remediation projects. In addition, a solidification process was evaluated by mixing treated sediments from the thermal desorption process with various proportions of cementitious material. The solidified blocks were sampled, and analyzed to determine the effectiveness of the solidification.


1.2.1 Watershed Description
The watershed of Buffalo River and its tributaries, Cayuga, Buffalo, and Cazenovia creeks is located in the west central portion of New York State (Figure 1). The land area is roughly triangular in shape. Buffalo and Cayuga creeks originate in the Allegheny Plateau and flow northwest toward Lake Erie. Buffalo Creek rises near the town of Java and flows northwesterly to its confluence with Cayuga Creek in the town of West Seneca. The drainage area of Buffalo Creek is 150 square miles (New York State DEC, 1989). Cayuga Creek, with a drainage area of 128 square miles, rises near North Java Station and flows westerly through the northern part of the Buffalo River watershed. The confluence of Cayuga Creek and Buffalo Creek form the head of the Buffalo River.

Cazenovia Creek generally flows north from its head waters near Springville, New York to its confluence with the Buffalo River within the Buffalo, New York city limits. The drainage area of Cazenovia Creek is 138 square miles. From Cazenovia Creek, the Buffalo River flows westerly to its mouth at the eastern end of Lake Erie. Overall, the Buffalo River is 8.1 miles in length and its drainage area is approximately 446 square miles.

The Buffalo River and its sediments have been polluted by over 50 years of industrial and municipal discharge and disposal of waste. Fishing and quality of aquatic life within the Area of Concern (Figure 2) have been impaired by heavy metals and polycyclic aromatic hydrocarbons (PAHs) in sediments. Fish and wildlife habitat have been degraded by alterations to the river including modifications to the shoreline such as bulkheading. Levels of metals and cyanides in the sediment prevent open lake disposal of sediments dredged from the river. Other potential sources of pollution to the Buffalo River include inactive hazardous waste sites, combined sewer overflows, and other point and non-point sources of pollution. While the Buffalo River sediments are contaminated, they are not considered "toxic" or "hazardous" based on strict regulatory definitions, and are therefore not subject to the appropriate regulations of the Toxic Substances Control Act (TSCA) or the Resource Conservation and Recovery Act (RCRA).

1.2.2 Status of Remedial Action Plan
New York State Department of Environmental Conservation (NYSDEC) and other Federal, State, and local agencies have and continue to carry out remediation of environmental problems along the Buffalo River. NYSDEC completed and issued the Buffalo River Remedial Action Plan (RAP) in November 1989. The RAP contained initial agency commitments to implement the remedial action strategy. To track implementation of the RAP, NYSDEC has issued annual reports to illustrate the progress on remediation by listing accomplishments of the past year and describing commitments for the current year.

To assist NYSDEC in the remediation process, a Remedial Advisory Committee (RAC) was formed in 1990. The RAC is representative of concerned groups within the community that have an interest in the Buffalo River. These groups include government officials, public interest groups, economic interests, and private citizens.

The following is a brief summary of RAC activities on the Buffalo River. A flow activated sampling station was established by NYSDEC to assist in stream water quality monitoring (New York State Department of Environmental Conservation, 1992). Event related sampling has been undertaken and will be continued into 1993. Sediment transport modeling is being conducted by the USEPA under the ARCS program. A dredging demonstration was conducted in 1992 by the Corps of Engineers to evaluate the efficiencies of several dredge types. Phase I investigations for all 36 inactive hazardous waste sites have been completed, while all but seven Phase II investigations have been completed. Remedial Investigation/Feasibility Studies (RI/FS) were completed for three sites in 1991-92, while two additional RI/FS's are underway. A combined sewer system model has been developed and verified for the main interceptors of the Buffalo Sewer Authority collection system. Operational simulations have been undertaken and cost estimates of alternatives for overflow reduction/treatment have been developed. A plan to assess fish and wildlife habitat conditions and improvement potential has been developed. Habitat assessment field work has been initiated by NYSDEC and will be completed in 1993.

1.2.3 Sediment Physical/Chemical Character Sources of Sediments--
The major source of sediment in the Buffalo River is in runoff from the surrounding watershed. Depending on factors such as river velocities and discharge, channel topography, bank erosion and wind, much of the sediment originating in runoff is either deposited in the river channel bottom or is carried to areas further downstream. A large portion of this sediment accumulates in the Buffalo River Federal Navigation Channel. Sediment Pollution--
The Buffalo River watershed is comprised of three major streams which converge at or along its mainstem: Cayuga, Buffalo, and Cazenovia creeks. Within the watershed major land usage is industrial and commercial, with some agricultural usage. Flows into the Buffalo River watershed originate in part from a variety of point and non-point source industrial activities in the watershed, including inactive hazardous waste sites and combined sewer outflows/municipal waste discharges (New York State D.E.C., 1989). These sources contribute to the bottom sediment contamination in the river. Polynuclear aromatic hydrocarbons and metals are contaminants of particular concern in Buffalo River sediments. Sediment Characteristics and Quality--
Historic and recent sediment particle size analyses indicate that bottom sediments within the Buffalo River are comprised of silts and clays, with some sands. Particle size and chemical (inorganic and organic) analyses and 96-hour acute toxicity tests (bioassays) were performed on surface grab samples obtained from the Buffalo River Federal Navigation Channel in 1989 (Aqua Tech Environmental Consultants, 1989). Particle size analysis of the sediment samples indicates they consist primarily of silts and clays (approximately 65 to 99 percent), with some sands (approximately 1 to 35 percent). Regarding inorganic sediment contamination, the results of bulk inorganic analysis performed under the 1989 program showed that most of the sediments were contaminated with elevated levels of numerous metals, including arsenic, barium, copper, iron, manganese, nickel, and zinc (Table 1). The 1989 sediment testing program included analyses for volatile organics, PAHs and polychlorinated biphenyls (PCBs). Table 2 summarizes volatile organics data on sediments. Generally, volatile organics were not detected in sediments with the exception of low levels of 1,3-Dichlorobenzene and high levels of toluene on portions of the Buffalo River. PAH levels, shown in Table 3, ranged from non-detectable to about 2.4 micrograms per gram (ug/g) (benzo(b)fluoranthene). Total PAHs ranged from 5.44 to 12.15 ug/g. PCB and pesticide data summarized in Table 4 show non-detectable levels in the sediments.

The USEPA's Large Lakes Research Station of Grosse Ile, Michigan sampled sediments along the Buffalo River and Buffalo Ship Canal in 1989, 1990, and 1991 with a 4-inch diameter vibracore unit. Results from testing performed on samples collected outside the navigation channel in 1989 show concentration levels for 12 metals at 10 sites along the Buffalo River (Figure 3 and Table 5). Concentration levels for chromium (Cr) ranged from less than 13 ug/g to 312 ug/g while concentration levels for mercury (Hg) ranged from 0.0109 to 1.93 ug/g. Lead (Pb) concentrations ranged from 28 to 314 ug/g while zinc (Zn) concentrations ranged from 32 to 900 ug/g. In general, the highest concentration levels of metals were in the terminal end of the Buffalo Ship Canal and in the middle third reach of the Buffalo River.

Test results for 20 organic parameters (PAHs) analyzed at 9 of the 10 sampling sites are given in Table 6. Generally the highest concentration of PAHs were at sample site 0601 in the Buffalo River and 0101 at the terminal end of the Buffalo Ship Canal. Benzo(a)pyrene concentrations ranged from undetectable at 54 nanogram per gram (ng/g) to 2500 (ng/g) at sample site 0601.

In 1990 and 1991 sediment vibracore samples were collected by USEPA in the Buffalo River. Generally, approximately 1 to 3 meter core samples were taken and analyzed. Analytical results indicated that sediment contamination is either (1) relatively low and consistent with respect to depth, or (2) increases with respect to depth to a maximum level at which point a relatively clean, natural lacustrine clay layer is reached (U.S. Army Engineer District, Buffalo, 1992).

Areas sampled during the 1991 program are shown on Figure 4. Results of the 1991 sampling revealed that, in general, lightly to moderately polluted sediments overlay heavily polluted sediments as shown in concentrations of chromium, lead, zinc, and PAHs. Some of the core samples extended through the heavily polluted sediments into underlying moderately and lightly polluted sediments at core depths of roughly 3 to 4 meters. Many of the vibracore samples met refusal at a depth of 3 meters or less and did not appear to penetrate deep enough to extend through the heavily polluted sediments and into the underlying moderately and lightly polluted sediments.


  1. Inorganic Analysis of Surface Sediment Grab Samples
  2.  Volatile Organics Data on Surface Sediment Grab Samples
  3.  PAH Data on Surface Sediment Grab Samples
  4.  Pesticide and PCB Data on Surface Sediment Grab Samples
  5.  Concentrations of Metals in Ten Buffalo River Sediment Samples
  6.  Concentrations of Polycyclic Aromatic Hydrocarbons in Ten Buffalo River Sediment Samples
  7.  Process Parameter Values as Measured by RETEC, Inc. (English Units)
  8.  Process Parameter Values as Measured by RETEC, Inc. (SI Units)
    1.  Solidification/Stabilization Mixes
  9.  Cost of Thermal Desorption Pilot Scale Demonstration
  10.  Results of Vapor Monitoring by RETEC, Inc.
  11.  Summary of Air Sampling and Analytical Procedures: E-Three/Battelle
  12.  Air Emissions of Polychlorinated Biphenyls in Micrograms Per Dry Standard Cubic Meter 44
    1.  Air Emissions of Particulates in Micrograms Per Dry Standard Cubic Meter
    2.  Air Emissions of Polycyclic Aromatic Hydrocarbons in Micrograms Per Dry Standard Cubic Meter
    3.  Air Emissions of Dioxins in Micrograms Per Dry Standard Cubic Meter
    4.  Air Emissions of Furans in Micrograms Per Dry Standard Cubic Meter
  13.  Analytical Parameters for Sediment Samples
  14. Analytical Parameters for Water Samples
  15. Solids/Liquids Mass Balance
  16.  Percent Total Solids in Sediment
    1.  Percent Total Solids in Condensate
  17.  Percent Volatile Solids in Sediment
  18.  Correlation Coefficients for Volatile Solids Removal
  19.  Lead in Sediment
    1.  Lead in Condensate (Filtered)
  20.  Chromium in Sediment
    1.  Chromium in Condensate (Filtered)|
  21.  Copper in Sediment
    1.  Copper in Condensate (Filtered)
  22.  Mercury in Sediment
    1. 22B Mercury in Condensate (Filtered)
  23.  Summary of Calculations: Chromium
    1. Summary of Calculations: Copper
    2.  Summary of Calculations: Lead
    3.  Summary of Calculations: Mercury
  24.  Low Molecular Weight (< 3 Rings) PAHs in Sediment
    1.  Low Molecular Weight (< 3 Rings) PAHs in Condensate
  25.  High Molecular Weight (> 3 Rings) PAHs in Sediment
    1.  High Molecular Weight (> 3 Rings) PAHs in Condensate
  26.  Summary of Calculations: Low Molecular Weight PAHs
    1.  Summary of Calculations: High Molecular Weight PAHs
  27.  Total PAHs in Sediment
    1.  Total PAHs in Condensate|
  28.  Solvent Extractables in Sediment
    1. Solvent Extractables in Condensate
  29. Summary of Calculations: Solvent Extractables
  30.  Total Organic Carbon in Sediment
    1.  Total Organic Carbon in Condensate
  31.  Summary of Calculations: TOC
  32.  Total PCB in Sediment
    1.  Total PCB in Condensate
  33. Summary of Calculations: PCB in Solids
  34.  Solidification/Stabilization Unconfined Compressive Strength (UCS)
  35.  Results of Residue Stabilization
  36.  Sequential Batch Leach Test (SBLT) for Metals
  37.  Cost Estimate for Remediating 10,000 Cubic Yards of Sediment
  38.  Cost Estimate for Remediating 100,000 Cubic Yards of Sediment


  1.  Buffalo River Watershed
  2.  Buffalo River Area of Concern
  3.  Buffalo River Master Station Locations October 1989
  4.  Sediment Quality Survey
  5.  Location of Confined Disposal Area Number Four
  6.  Location of Pilot Scale Demonstration
  7.  Plan for Demonstration Site
  8.  Sediment Screening Device
    1. A Thermal Desorption Unit and Screw Processor
  9.  Flow Diagram for Thermal Desorption Process
  10.  Demonstration Flow Diagram with Corps of Engineers Sampling Points
  11.  Percent Solids Versus Exit Temperature of Solids
  12.  Percent Volatile Solids Versus Exit Temperature of Solids
  13.  Concentration of Low Molecular Weight PAHs in Sediment Versus Exit Temperature of Solids
  14. Concentration of High Molecular Weight PAHs in Sediment Versus Exit Temperature of Solids
  15. Concentration of Solvent Extractables in Sediment Versus Exit Temperature of Solids
  16.  TOC (mg/g Solids) Versus Exit Temperature of Solids
  17.  Results of Residue Stabilization: TOC Analysis of Extracts From Sequential Batch Leach Test (SBLT)

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