The International Information Center for Geotechnical Engineers

Stabilization/Solidification - 8.1 Case Study #1

8.1 Case Study #1: In-Situ treatment at South 8th Street Landfill Superfund Site, West Memphis, AR 

The South 8th Street Landfill was a 30-acre industrial and municipal waste landfill. Before becoming a landfill, the site was excavated for gravel, resulting in numerous borrow pits. After 1957, the pits were used for disposal of industrial and municipal wastes. Between 1960 and 1970, waste oil sludge from a nearby refinery was deposited on 2.6 acres of the landfill. EPA conducted borings between 1981-1988 and found the oil sludge soil was contaminated with PAHs, PCBs, and lead.

In-situ mixing with auger reagents was utilized to remediate the soil. The following mixing proportions were used:

  • Soil 64.5 percent
  • AG limestone 16.1 percent
  • Portland cement 12.9 percent
  • Fly ash 6.5 percent

 Site remediation was completed over the course of two years between 1998 and 2000. Treatment costs were approximately $106/cyd. Sampling during a five year review of the contaminated site concluded that the site achieved remediation goals and chemical and physical performance standards.

 

Comments  

 
0 #5 Lizzie Grobbel 2013-04-24 18:49
Quoting Sally Simpson:
Lizzie and Zhijie,

congratulations on an excellent review. I would agree with the comment about the in-situ vs. ex-situ. Make sure you address this.

Sally,

Thank you very much for your comments and for pointing out the ex-situ vs. in-situ error. The field setup section has been corrected to reflect this error.

Lizzie and Zhijie
 
 
+1 #4 Lizzie Grobbel 2013-04-24 18:47
Quoting Chris Ryan P.E.:
There are several places where the authors are confusing the terms in situ and ex-situ stabilization and the advantages assocated with them. We would not define the movement of materials to a mixing pit and as in situ. Generally in situ is the use of some device, usually a mixing auger to mix the soils in place. As a result, there are no emissionsof volatiles or other materials, no dust, etc.

Chris,

Thank you very much for the valuable comments and for pointing out the ex-situ vs. in-situ error. We read through the references again and modified the field setup section to reflect this error.

Lizzie and Zhijie
 
 
0 #3 Sally Simpson 2013-04-05 15:36
Lizzie and Zhijie,

congratulations on an excellent review. I would agree with the comment about the in-situ vs. ex-situ. Make sure you address this.
 
 
0 #2 Chris Ryan P.E. 2013-03-21 11:09
This seems to be a pretty thorough review. The current state of practice is that these same technologies are being used with increasingly sophisticated reagents to chemically treat the soils as opposed to physically stabilizing them. The addition of activated carbon, specialized clays and granulated iron are examples of treatment additives.
 
 
0 #1 Chris Ryan P.E. 2013-03-21 10:58
There are several places where the authors are confusing the terms in situ and ex-situ stabilization and the advantages assocated with them. We would not define the movement of materials to a mixing pit and as in situ. Generally in situ is the use of some device, usually a mixing auger to mix the soils in place. As a result, there are no emissionsof volatiles or other materials, no dust, etc.
 

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