Figure 4-28: Typical Contaminated Soil Excavation Diagram
Contaminated material is removed and transported
to permitted off-site treatment and/or disposal facilities. Some pretreatment of the
contaminated media usually is required in order to meet land disposal restrictions.
disposal facilities (CDFs) are engineered structure enclosed by dikes and designed to
retain dredged materials. A CDF may have a large cell for material disposal, and adjoining
cells for retention and decantation of turbid, supernatant water. A variety of linings
have been used to prevent seepage through the dike walls. The most effective are clay or
bentonite-cement slurries, but sand, soil, and sediment linings have also been used.
Location and design are two important CDF consideration. Terms to consider in the
location of a CDF are the physical aspects (size, proximity to a navigable waterway), the
design/construction (geology/hydrology), and the environmental (current use of the area,
environmental value, and environmental effects). The primary goal of a CDF design is
minimization of contaminant loss. Caps are the most effective way to minimize contaminant
loss from CDFs, but selection of proper liner material is also an important control on
CDFs. Finally, CDFs require continuous monitoring to ensure structural integrity.
Operation and maintenance duration lasts as long as the life of the facility.
E1 (Waste Removal-Soils)
R1 (Waste Removal-Sludges)
S1 (Waste Removal-Non-soil Solids)
Excavation and off-site disposal is applicable to the complete
range of contaminant groups with no particular target group. Excavation and off-site by
relocating the waste to a different (and presumably safer) site.
Factors that may limit the applicability and effectiveness of
the process include:
- Generation of fugitive emissions may be a problem during operations.
- The distance from the contaminated site to the nearest disposal facility with the
required permit(s) will affect cost.
- Depth and composition of the media requiring excavation must be considered.
- Transportation of the soil through populated areas may affect community acceptability.
- Disposal options for certain waste (e.g., mixed waste or transuranic waste) may be
limited. There is currently only one licensed disposal facility for radioactive and mixed
waste in the United States.
- Contaminants can potentially migrate from CDF from several pathways, including effluent
discharge to surface water, rainfall surface runoff, leachate into ground water,
volatilization to the atmosphere, and dike uptake.
- CDFs can develop odor problems as well as mosquito and insect problems without proper
design and maintenance.
A detailed discussion of these data elements is provided in Subsection 2.2.1 (Data Requirements for Soil, Sediment,
The type of contaminant and its concentration will impact off-site disposal
requirements. Soil characterization as dictated by land disposal restrictions (LDRs) are
required. Most hazardous wastes must be treated to meet either RCRA or non-RCRA treatment
standards prior to land disposal. Radioactive wastes would have to meet disposal facility
waste form requirements based on waste classification.
Excavation and off-site disposal is a well proven and readily
implementable technology. Prior to 1984, excavation and off-site disposal was the most
common method for cleaning up hazardous waste sites. Excavation is the initial component
in all ex situ treatments.
The rate of excavation depends on a number of factors,
including the number of loaders and trucks operating. The excavation of 18,200 metric tons
(20,000 tons) of contaminated soil would typically require about 2 months. Disposal of the
contaminated media is dependent upon the availability of adequate containers to transport
the hazardous waste to a permitted facility.
CERCLA includes a statutory preference for treatment of contaminants, and excavation
and off-site disposal is now less acceptable than in the past. The disposal of hazardous
wastes is governed by RCRA (40 CFR Parts 261-265), and the U.S. Department of
Transportation (DOT) regulates the transport of hazardous materials (49 CFR Parts 172-179,
49 CFR Part 1387, and DOT-E 8876).
DOE has demonstrated a cryogenic retrieval of buried waste system, which uses liquid
nitrogen (LN2) to freeze soil and buried waste to reduce the spread of contamination while
the buried material is retrieved with a series of remotely operated tools. Other
excavation/retrieval systems that DOE is currently developing include a remote excavation
system, a hydraulic impact end effector, and a high pressure waterjet dislodging and
conveyance end effector using confined sluicing.
Cost estimates for excavation and disposal range from $300 to
$510 per metric ton ($270 to $460 per ton) depending on the nature of hazardous materials
and methods of excavation. These estimates include excavation/removal, transportation, and
disposal at a RCRA permitted facility. Additional cost of treatment at disposal facility
may also be required. Excavation and off-site disposal is a relatively simple process,
with proven procedures. It is a labor-intensive practice with little potential for further
automation. Additional costs may include soil characterization and treatment to meet land
Additional cost information can be found in the
Hazardous, Toxic, and Radioactive Wastes (HTRW) Historical Cost Analysis System (HCAS)
developed by Environmental Historical Cost Committee of Interagency Cost Estimation Group.
Technologies: Field Scale Demonstration Project in North America,
of Remediation Case Studies, Volume 4, June, 2000, EPA
Church, H.K., 1981. Excavation Handbook,
McGraw Hill Book Co., New York, NY.
Guide to Documenting and Managing Cost and Performance Information for
Remediation Projects - Revised Version, October, 1998, EPA 542-B-98-007
DOE, 1995. Technology Catalogue, Second
Edition, Office of Environmental Management and Office of Technology
EPA, 1991. Survey of Materials-Handling Technologies Used at Hazardous
Waste Sites, EPA, ORD, Washington, DC, EPA/540/2-91/010.
EPA, 1992. McColl Superfund Site Demonstration of a Trial Excavation,
EPA RREL, series include Technology Evaluation EPA/S40/R-92/015, PB92-226448; Applications
Analysis, EPA/540/AR-92/015; and Technology Demonstration. Summary, EPA/540/SR/-92/015.
EPA, 1997. Best
Management Practices (BMPs) for Soil Treatment Technologies: Suggested Operational
Guidelines to Prevent Cross-media Transfer of Contaminants During Clean-UP Activities,
EPA OSWER, EPA/530/R-97/007.
- EPA Demo: Carter
Industrial, MI; Shaver's Farm, GA; Hopkinsville, KY
- EPA Demo:IN, MI, OH,
SD, VA, WI
- DOE Integrated Demo:
(1,2) Chemical and Mixed Waste Landfills, Albuquerque, NM; (3) Mixed Waste Landfill at
Kirkland AFB, NM
- DOE Integrated Demo:
Fernald Environmental Project Cincinnati, OH
Points of Contact:
General FRTR Agency Contacts
Technology Specific Web Sites:
Government Web Sites
Non Government Web Sites
A list of vendors offering Soil
Excavation, Retrieval, and Off-Site Disposal Treatment is available from
REACH IT which combines information from three established EPA databases,
the Vendor Information System for Innovative Treatment Technologies (VISITT),
the Vendor Field Analytical and Characterization Technologies System (Vendor
FACTS), and the Innovative Treatment Technologies (ITT), to give users access to
comprehensive information about treatment and characterization technologies and
Health and Safety: