Waterloo Barrier Publications
Contamination Clean Up - “The Go To Technology For Environmental Containment”
At a historic airbase in Newfoundland and Labrador, a unique environmental containment system called the Waterloo Barrier® is being used to entomb decades of domestic and industrial waste. The Goose Bay Remediation Project is a multi-year, multi-million-dollar environmental program for the Department of National Defence. It is centred around a storied Second World War airbase in Newfoundland and Labrador known as 5 Wing Goose Bay.
A New Type of Steel Sheet Piling With Sealed Joints for Groundwater Pollution Control
A new type of steel piling with joints that can be sealed after driving has been developed. Walls constructed of this sheet piling serve two purposes: to contain zones of contamination so that contaminants will not migrate offsite, and to provide an isolated subsurface environment in which subsurface remediation technologies can be applied with excellent environmental safety. The sheet pile joints incorporate a cavity that can be filled with sealant after driving, and that provides access for quality control operations. Field hydraulic tests indicate that hydraulic conductivity values are low enough for environmental control applications. Sealable joint sheet pile cutoff walls overcome many of the practical limitations associated with other cutoff wall types.
In Situ Remediation of Contaminated Ground Water: The Funnel-and-Gate System
The funnel-and-gate system for in site treatment of containment plumes consists of low hydraulic conductivity cutoff walls with gaps that contain in site reactors, such as reactive porous media, that remove contaminants by abiotic or biological processes. Funnel- and-gate systems can be installed at the front of plumes to prevent further plume growth, or immediately downgradient of contaminant source zones to prevent contaminants from moving into plumes. Cutoff walls (the funnel) modify flow patterns so that ground water flows primarily through high conductivity gaps (the gates). This approach is largely passive in that after installation, in situ reactors are intended to function with little of no maintenance for long periods. This approach contrasts with the energy and maintenance- intensive character of pump-and-treat systems. This paper describes the funnel-and-gate concept, and uses two-dimensional computer simulations to illustrate the effects of cutoff wall and gate configuration on capture zone and shape and on the residence time for reaction of contaminants in gates.
The Waterloo Barrier® steel sheet piling, incorporates a cavity at each interlocking joint that is flushed clean and injected with sealant after the piles have been driven into the ground to form a vertical cutoff wall. The installation and sealing procedures allow for a high degree of quality assurance and control. Bulk wall hydraulic conductivity of a 10-8 to 10-10 cm/sec have been demonstrated at field installations.
Recent case histories are presented in which Waterloo Barrier™ cutoff walls are used to prevent off-site migration of contaminated groundwater or soil gases to adjacent property and waterways. Full enclosures to isolate DNAPL source zones or portions of contaminated aquifers for pilot-scale remediation testing will also be described. Monitoring data will be used to demonstrate the effectiveness of the Waterloo Barrier™ in these applications.
Use of Waterloo Barrier in Progressive Reclamation of Hydrocarbon Plume
Historic leaks of diesel fuel had resulted in hydrocarbon contamination of soil and groundwater on several neighbouring properties in North Vancouver, B.C., requiring remediation by separate parties. A Waterloo Barrier® cut-off wall was installed over a length of 270m and a maximum depth of 12m effectively splitting the contaminant plume into two separate entities. On one side of the barrier, extraction wells and a shallow drain were installed and operated to prevent overtopping and/or movement of contaminated groundwater around the barrier. On the other side, the contaminated soil was excavated and replaced with clean fill. During excavation, a secondary sheet pile wall with cross beams and/or anchors was used to provide structural support for the cut-off wall. The groundwater extraction system on the upgradient (contaminated) side of the cut-off wall was operated over a period of three years to prevent re-contamination of the remediated area. Detailed monitoring of groundwater levels and water quality has been carried out to demonstrate successful operation of this hydraulic barrier system
Funnel and Gate System Directs Plumes to In Situ Treatment
The Waterloo Center for Groundwater Research has developed Funnel-and-Gate systems that isolate contaminant plumes in ground water and funnel the plumes In Situ bioreactors. The Funnel-and-Gate consists of low hydraulic conductivity cut-off walls with gaps that contain In Situ reactors (such as reactive porous media), which remove contaminants by abiotic or biological processes. The cut-off walls (the funnel) modify flow patterns so that the ground water flows primarily through conductivity gaps (the gates). Ground water plumes are thus directed through the In Situ reactors in the gates where physical, chemical, or biological processes remove contaminants from ground water. Remediated ground water exits the downgradient side of the reactor. Funnel-and-Gate systems can be installed at the front of plumes, to prevent further plume growth, or immediately downgradient of contaminant source zones to prevent contaminants from developing into plumes.
Containment / Stabilization of Subsurface Hydrocarbon Contamination at Texaco Refinery
Two major contaminant/ stabilization projects have recently been conducted at the former Texaco refinery in Casper, Wyoming. These include installation of the state-of-the-art subsurface barrier wall, and removal of subsurface piping and hydrocarbon source areas. Other corrective action activities, such as preparation of a CAMU for clean-up wastes, have also been undertaken. These innovative and state-of-the-art project have, in keeping with the recent RCRA reforms accelerated the implementation of corrective action goals at this GPRA facility, including meeting the Environmental Indicator (EI) for ground water. The following is a summary of these significant and highly successful projects. Attachment A contains a detailed description of these projects.
Control of contaminated groundwater - Environmental Science & Engineer (March 1999 Issue)
Low Permeability containment walls are increasingly used in groundwater pollution control and remediation. Containment enclosures minimize or eliminate the need for contaminant plume control by groundwater pumping and water treatment. Contaminants are prevented from moving off site while site control activities, such as source removal and plume remediation, are carried out in the isolated subsurface environment inside the walled enclosure.
New Passive and semi-passive treatment technologies for the interception and In Situ treatment of groundwater contaminants provide alternatives to conventional pump-and-treat approaches. In systems such as these, containment walls can be used to direct plumes into subsurface treatment zones containing reactive media. This article describes the development and recent applications of sealable joint steel sheet piling for groundwater containment wall construction.