The Waterloo Barrier® is a groundwater containment wall formed of sealable steel sheet piling developed in 1989 by researchers at the Waterloo Centre for Groundwater Research, University of Waterloo*. The Barrier incorporates a sealable cavity at the interlocking joint between piles that can be flushed clean, inspected, and then sealed after the piles have been driven into the ground. The system allows for documentable quality assurance and a high degree of quality control. Bulk wall hydraulic conductivities of 10-8 to 10-10 cm/sec have typically been achieved in University-conducted & U.S. Air Force-conducted testing.

The Waterloo Barrier® can be used to prevent off-site migration of contaminated groundwater or gases, or can be installed to isolate a site while remedial actions are in progress. It can also act as a structural wall during excavation or assist with site dewatering on civil engineering projects.

Installation

Rapid installation and sealing

Minimal disturbance to the site during construction
Limited site access is less of a problem compared to alternative cutoff wall technologies
Easily installed in areas with high water tables and surface water
Easily adapted to irregular layouts
QA / QC & Performance

Easy to inspect and monitor for superior QA/QC during construction
Continuality of the wall in place in the ground can be verified and documented
Predictable hydraulic performance
Field Applications

Can function as a groundwater cut-off wall and/or a structural wall for excavations
Long service life for permanent installations
Easily removed where applications are temporary

Since 1989, more than 20 test cells have been installed by UW for field research purposes at Borden and another site in southwestern Ontario. These have ranged in dimensions from 1 by 3 to 9 by 9 m, and have extended to depths ranging from approximately 3 to 15 m. Several of these cells have been constructed with concentric double walls, a configuration which facilitates rigorous hydraulic testing. Figure 1 shows a schematic diagram of such a double-walled cell in which a hydraulic test was undertaken. The cell extends to a depth of 14.7 m through a surficial sand aquifier into an underlying aquitard. The sealable cavities were injected with a benonite slurry. For the test, the water level in the moat bounded by the two walls was maintained at a constant level. At the start of the test, the water level in the internal cell was raised by approximately 1 m relative to the natural water table in the vicinity of the cell. As the test proceeded, the decline in water level in the internal cell was monitored with time. Corrections were made to these levels to account for losses by evaporation.

Field Applications

The Waterloo Barrier® is a versatile containment wall. Applications include:

Environmental

Deep, enclosing barriers around hazardous waste sites or municipal landfills to confine containment plumes and/or landfill gases
Shallow, enclosing barriers to contain petroleum products or other light contaminants which float on the water table
Enclosures to control future groundwater contamination at new industrial or waste disposal sites
Temporary, enclosing barriers to facilitate removal or in-situ remediation of contaminants
Barriers along shorelines to prevent seepage of contaminated groundwater into waterways
Funnelling or directing contaminant plumes to enhance the efficiency of pump-and-treat techniques
Structural wall for excavation of contaminated soils
Pilot scale remediation testing in contaminated aquifers under confined conditions
Non-Environmental

Groundwater control in construction projects involving excavating and tunnelling
Isolation of accidental spills
Cofferdams