Barrier Technologies for Environmental Management Summary of a Workshop (1997) / Chapter Skim
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New Technologies for Subsurface Barrier Wall Construction
New Technologies for Subsurface Barrier Wall Construction
Pages 41-53
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From page 41... ...
Table 1 presents a partial listing of available barrier wall technologies. TABLE 1 Subsurface Barrier Wall Technologies Compacted Clay Soil-Bentonite Slurry Trench Self-Harden~ng Slurries Plastic Concrete Slurry Trench Deep Soil Mixing let Grouting Vibrating Beam Ground Freezing Waterloo Barrier(~)
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From page 42... ...
Deep Soil Mixing Barrier Walls Development of deep soil mixing (DSM) barrier walls can be traced back to the early 1960s when the Intrusion Prep akt Co.
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From page 43... ...
Waterloo Sealable Sheet Piles The University of Waterloo has developed a sealable sheet pile wall that reportedly is capable of achieving bulk hydraulic conductivities of less than 10-8 centimeters per second. This product, which has patents or patents pending in several countries, is termed the Waterloo garner_.
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From page 44... ...
When slag cement with a slag to Portland cement ratio of 3:1 to 4:1 is combined with bentonite slurry, the permeability of the -7 ~ mixture is generally in the range of 10 to 10 centimeters per second (lefferis, 1985; Chipp, 19901. The use of slag cement also enhances chemical resistance and ultimate strength.
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From page 45... ...
lo-6 10-5 to 10-6 10-3 to 10-5 -l to 10-3 lo-l Approximate Relationship Between Soil Permeability and Groutability (Karol, Groutability (Ability of Soil to Receive Grout) Ungroutable Groutable with difficulty by grouts with viscosity <5 cP and ungroutable with grouts having a viscosity >5 cP Groutable with low-viscosity grouts but difficult with grouts with a viscosity greater than 10 cP , ~ Groutable with all commonly used chemical grouts Requires suspension grouts or chemical grouts containing a filler material The Department of Energy, through its Sandia National Laboratories, has been conducting a study of two grouting materials, a montan wax emulsion and a glyoxal-modified sodium silicate material.
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From page 46... ...
The initial soil permeability was the same as that cited above for the montan wax permeation study. It also should be noted that they were unable to grout soil with a permeability less than 5 x 10-4 centimeters per second with either the montan wax emulsion or the modified glyoxal sodium silicate material.
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From page 47... ...
Alternatively, the panels can be lowered into a previously excavated slurry trench. Gundle uses a jointing system that consists of an interlocking joint similar to steel sheet piling.
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From page 48... ...
The joint interlock is fusion welded to vertical panels of varying width prior to a placement. The panels are then lowered into a slurry trench or specialized steel trench boxes (for shallower trenches)
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From page 49... ...
Barrier walls that fail to penetrate deeply enough to key into an aquitard at all are usually only marginally effective in reducing groundwater flow (Mutch et al., 19811. The growing importance of barrier walls, together with the fact that in many geologic environments, suitable aquitards may be at depths of 150 feet or more, has spawned considerable interest and advancement in the technologies to construct deep barrier walls (defined herein as walls greater than ~ 50 feet in depth)
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Plastic concrete walls constructed in short panel sections of one to three clamshell bites have become the preferred type of barriers for deep walls. Alternately, a hydromill can be used.
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From page 51... ...
However, rather than being withdrawn prior to excavation of the adjacent panel, it is left in place to serve as a guide to a specifically designed excavating tool that slides down the beam. The beam is pulled laterally away from the concreted primary panel once the secondary panel is fully excavated.
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1993. In Situ Permeability Reduction and Chemical Fixation Using Colloidal Silica.
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From page 53... ...
His work has included the investigation and remedial design of hundreds of municipal and hazardous waste disposal sites, including dozens of Superfund sites. He has designed and, in most cases, supervised construction of 14 miles and 1,500,000 square feet of subsurface cutoff wall, 2 i/2 square miles of low permeability landfill caps, 15 miles of retrofitted leachate collection systems, and numerous groundwater extraction systems ranging in size from 50,000 gallons per day to 2,000,000 gallons per day.
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