1. Web-based Class Project on Geoenvironmental Remediation
Soil Washing
Prepared by:
Jonathan Hubler
Ken Metz
With the Support of:
Report prepared as part of course
CEE 549: Geoenvironmental Engineering
Winter 2013 Semester
Instructor: Professor Dimitrios Zekkos
Department of Civil and Environmental Engineering
University of Michigan

2. Outline Main Concept Theoretical Background Applicability
Advantages/Disadvantages
Field Setup
Examples of Different Systems
Costs
Case Histories

3. Main Concept Ex-Situ Remediation Technique
Contaminants are prone to bind to fine grained soils, which are prone to bind to coarse grained soils
General Process:
Wash soil with liquid (often with chemical)
Scrub Soil
Separate clean soils from contaminated soil and washwater

4. Main Concept Volume reduction process
Washed soil may be reused as backfill
Six Steps:
Pretreatment
Separation
Coarse-grained treatment
Fine-grained treatment
Process water treatment
Residuals management

5. Process
Source: US EPA 1996

6. Theoretical Background
Contaminants adhere to fine grained soils, which adhere to coarse grained soils (adhesion and compaction)
Physiochemical processes involved:
Desorption (contaminants desorbed from soil)
Dissolution/solubilization (pH changes from reactions with washwater)
Oxidation reduction (results in desorption or solubilization of contaminants)

7. Theoretical Background
Equation to determine contaminant concentration:
At equilibrium:
Equation to determine removal efficiency:

8. Applicability Proven to effectively remove:
Petroleum and fuel residues
Radionuclides
Heavy metals
PCBs
PCP
Pesticides
Cyanides
Creosote
Semivolatiles
Volatiles

9. Applicability
Good to excellent at removing VOCs and metals from sandy and gravelly soils
The lower the silt/clay content the more effective soil washing will be
May not be applicable if contaminants adsorbed strongly
Large sites - at least 5000 tons of contaminated soil

10. Advantages Cost effective
Under ideal conditions – volume reduction of 90%
Reuse of cleaned soil
Closed system that can be controlled (pH, temp)
High rate cubic yards per day
Only a few permits

11. Disadvantages Large area for system
Predominantly effective for very coarse soils
Ineffective for soils containing more than 30-50% fines
Washwater may need special treatment ($)
May produce contaminated sludge
Air emissions from equipment ($)
Exposure of public to contaminants

12. Field Setup Varies depending upon site and project Typical plant:
125’ x 250’
Process tons per hour

13. Field Setup
Source: ART Engineering

14. Harbauer Soil Washing System
Source: US EPA 1996

15. Mobile Soil Washing System
Source: US EPA 1996

16. Cost Average: $150 to $250 per ton More cost effective for larger site
Costs:
Initial (bench scale)
Operational
Set-up and break down
Chemical analysis
Disposal

17. Source: FRTR 2006

18. Case Histories Twin Cities Army Ammunition Plant
Remediation of high levels of VOCs and heavy metals
Combination of soil leaching and soil washing used successfully
20,000 tons of soil treated (every 10 tons tested)
8 heavy metals removed, less than 175 ppm (initial level of lead 86,000 ppm)
Soil reused at site

19. System used at Twin Cities Site
Source: Fristad 1995

20. King of Prussia Technical Corp Site
Used for processing industrial liquid waste
19,200 tons of contaminated soil
Soil washing system – 25 tons/hr
First full-scale use of soil washing to a Superfund Site
Clean up levels met (e.g. – Cu (9070 mg/kg before, 860 mg/kg after)
Total cost $7.7 million

21. System used at KOP site
Source: US EPA 1995

22. Summary Ex-situ technique Volume reduction process
Good/Excellent for VOCs and heavy metals
Coarse grained soils more effective
At least 5000 tons to be cost effective
Average cost - $ per ton

23. References
ART Engineering. “Soil Washing at King of Prussia Superfund Site” < (Mar. 16, 2013). 
Contaminated Land: Applications in Real Environments (CL:AIRE). (2007, September). “Understanding Soil Washing.” TB13. < 16, 2013).
Federal Remediation Technologies Roundtable (FRTR). (2006). “Remediation Technologies Screening Matrix and Reference Guide: 4.19 Soil Washing.” < 16, 2013).
Fristad, W. E. (1995). “Case Study: Using soil washing/leaching for the removal of heavy metal at the twin cities army ammunition plant.” Remediation, 5(4),
Griffiths, Richard A. (1995). “Soil-washing technology and practice.” Journal of Hazardous Materials
Sharma, Hari D., and Krishna R. Reddy (2004). "Soil Remediation Technologies." Geoenvironmental Engineering: Site Remediation, Waste Containment, and Emerging Waste Management Technologies. Wiley, Hoboken, NJ,
United States Department of Energy (USDOE). (1998, July). “Cost and Performance Report: Chemical Extraction for Uranium Contaminated Soil, RMI Titanium Company Extrusion Plant Ashtabula Ohio.” USDOE.
United States Environmental Protection Agency (USEPA). (1996, April). “A Citizen's Guide to Soil Washing.” EPA 542-F
USEPA. (1995, March). “Cost and Performance Report: Soil Washing at the King of Prussia Technical Corporation Superfund Site Winslow Township New Jersey”. < 16, 2013)
USEPA. (1991, September). “Guide for Conducting Treatability Studies Under CERCLA: Soil Washing.” Washington D.C., EPA/540/2-91/020A.
USEPA. (1993, November). “Innovative Site Remediation Technology: Soil Washing/Soil Flushing.” EPA 542-B
USEPA (1983, September). “NPL Site Fact Sheet: King of Prussia, New Jersey.” < (Mar. 16, 2013).
USEPA (2010, September). “Superfund Remedy Report.” 13. EPA-542-R

24. More Information
More detailed technical information on this project can be found at: