Stephen G. Custeau, P.Eng., MBA, Quantum Murray LP

This presentation will present various case studies related to the design and construction of barrier and cut-off walls to either contain dissolved contamination on-site or actively treat dissolved contaminated through a funnel and gate approach (i.e., a combination of a barrier wall and treatment corridor).

Often barrier walls must be installed at the property line or leading edge of a dissolved contaminant plume, either to mitigate re-contamination of a remediated site or to mitigate further off-site migration of dissolved impacts. Barrier walls have also become key components of risk-based remediation programs at brownfield sites, where a control and cap strategy is employed. Numerous factors are involved in the selection of the appropriate barrier wall technology and include many of the following: hydraulic conductivity of the native formation; stratigraphy / soil type of the native formation; desired hydraulic conductivity of barrier wall; length and depth of the barrier wall; lifespan of the barrier wall; constructability issues; site development issues; QA/QC issues; and, cost.

Quantum Murray LP has installed numerous types of impermeable groundwater cut-off/barrier walls at sites across Canada, including: clay walls; bentomat walls; Waterloo Barriers; soil-bentonite admixtures; bentonite slurry walls; caisson walls; and, slurry slot excavations backfilled with concrete. All of these barrier walls were installed to prevent the migration of dissolved contamination. This presentation will address the above-noted factors for each type of barrier wall.

S.K. Roy1, , McGregor, R.2, Sauriol, J.1
1 Jacques Whitford Ltd.
2 Vertex Environmental Solutions Inc.

In December 2006, more than 800 litres of stove oil was released from exterior above ground storage tanks supplying stove oil fuel to two adjacent residences located in a mobile home park (the Site) west of Ottawa, Ontario. The stove oil releases occurred concurrently and petroleum product rapidly entered the subsurface, saturating the shallow permeable overburden soil in the vicinity of the residences. Initial clean up response included the removal of approximately 190 tonnes of impacted soil and fractured rock for off-site disposal.

Subsequent detailed site characterization included the installation of 47 boreholes / monitoring wells, hydraulic conductivity testing, hydraulic groundwater elevation monitoring and laboratory analyses for the contaminants of concern (BTEX and petroleum hydrocarbon fractions F1-F4). Results from the hydrogeological investigation indicated a shallow overburden consisting primarily of shallow sandy silt with some clay (on average 0.5 metres or less in thickness), overlying a fractured limestone bedrock of the March Formation. Site characterization confirmed a dissolved contaminant plume of approximately 1,300 square metres, which had developed down gradient of the spill area over a five month period, with an estimated plume front migration rate of approximately 0.2 metres per day. Considerable seasonal fluctuation of the local water table (2 - 3 m) also resulted in significant smearing of the contaminant layer within the subsurface.

Remedial challenges at the Site included the requirement for a rapid site clean-up with minimal disturbance to the residents. The Site is densely covered by mobile home units, and the entire park is supplied with potable water from two communal bedrock wells, located approximately 150 metres down gradient of the source area. Various remediation approaches were evaluated, including hoe-ram excavation, pump and treat, monitored natural attenuation, and in-situ remediation. Hoe-ram excavation was rejected as a result of the high cost and disturbance which would be required to reach remedial goals. Pump and treat was rejected as a result of the relatively long estimated operation period due to expected contaminant rebounding effects. Redox potential was documented to show that some natural biodegradation was occurring, however the rate of degradation was perceived as low compared to the advection of the plume front, posing potential risk to the downgradient water supply wells. Chemical oxidation was selected as the preferred remedial option as it offered the best potential to remediate the site under a controlled time table at acceptable costs.

The chemical oxidation remedial work plan consisted of the implementation of a preliminary pilot scale test, two full scale injections of a chemical oxidant (RegenOX), and one final injection of an oxygen release compound (ORC) to polish the groundwater and facilitate natural long term aerobic degradation in the subsurface. The oxidant was mixed on-site with potable water to comprise a solution of between 2.5 and 5 percent RegenOx. After initializing the mobile MOE Certificate of Approval, the pilot scale test was completed in July 2007 to assess the hydraulic and geochemical response of the site subsurface materials to the proposed injection program. The pilot test results confirmed that the radial area of influence of each injection site was on the order of 5 metres. In August of 2007, the first full scale injection was initiated, where approximately 13,100 litres of the RegenOx solution was injected in 23 injection wells. Good distribution of the oxidant was confirmed by the observed hydraulic and geochemical response in adjacent monitoring wells. The project is currently ongoing and a second injection is planned for late October, followed by the last polishing injection of ORC in mid-December 2007. Final concentrations of the contaminants of concern will be assessed and an evaluation of the effectiveness of the remedial program in meeting the remediation goals will be undertaken.

Josef Tomas, Ph.D., Ministry of the Environment,
Czech Republic

During the last 60 years, since the end of World War II, uranium mining and milling in the Czech Republic has caused an enormous devastation of the environment by means of waste dump accumulation, waste dumps left after uranium prospections, tailings impoundments and other workings. All these negative impacts influenced the quality of the environment and affected mainly surface and ground waters, soils and, simultaneously, polluted great areas of land and endangered the catchments of drinking water. The situation of this region is more critical due to the fact that the area belongs to the nature reservoir of water protection in North Bohemian Cretaceous Platform.

Jean Paré, P. Eng., Chemco Inc.

In-situ and ex-situ chemical oxidation technologies used in soil and groundwater remediation have evolved greatly over the past three years. These new techniques allow better removal rates and are applicable to a broader spectrum of contaminants. This comprehensive technology review covers all major oxidation techniques: hydrogen peroxide with regular fenton and modified fenton chemistry, sodium and potassium permanganate, sodium persulphate, sodium percarbonate and ozone. This presentation discusses the advantages and limitations in the application of each oxidant and covers the geological, hydrogeological and geochemical aspect of in-situ injection. A detailed case study is also presented at the end of the technology section. This will allow participants to better understand where and how these remediation technologies can be applied with success. The presentation also touches on the impact of chemical oxidation from a sustainable development point of view for remediation work.

Eric Bergeron, Eng., M.Sc.1, Mathieu Barbeau, Eng., M.Sc. 2, Adriana Peisajovich, Eng,.Ph.D3, Ginette Lajoie4
1 Golder Associates Ltd.
2 Golder Associates Innovative Applications Inc.
3 Transport Canada
4 Cree Regional Authority

The remediation technique selected consists of a soil chemical oxidation treatment with potassium permanganate combining in-situ and ex-situ treatment. The process developed is innovative because permanganate is not usually used for hydrocarbon treatment.

The ex-situ step of the soil mixing in the reactors allows a 50% reduction of hydrocarbons. This first phase of treatment required the design of efficient mixers, a perfect oxidant dosage and, more importantly, the optimization of the reactive agents’ addition sequence. The in-situ process allows for an increase in the percentage of hydrocarbon reduction from about 10 to 30%. The oxidant used has a kinetics that allows the retention of a residual concentration of permanganate in soils that oxidizes the most refractory hydrocarbons in the long run.

Sustainable development was a priority throughout the entire project, in order to minimize the economic, social and environmental repercussions. The site remediation, minimal use of fuel, recycling of dismantled metal, fixing of various installations on site, maximal implication of Cree labour (direct source of revenue and development of their competence), and finally, the possibility of an economic activity in the region constitutes, a heritage for future generations. The Canadian government has invested over $5 million for the realization of this project.

Robert Focht1, Dario Velicogna2, Monique Punt1,
and Carl E Brown2
1 Science Applications International Corporation (SAIC Canada)
2 Environment Canada, Emergencies, Engineering Technology Office

In-situ chemical oxidation (ISCO) is a rapidly emerging soil remediation technology. Although this technology is applied commercially, research is still ongoing, most notably on the use of new oxidants. Through ISCO, organic hazardous chemicals are oxidized, often to carbon dioxide and water, rendering them non-hazardous. The four most common oxidants used, on there own or in combination, for ISCO are peroxide, ozone, permanganate, and persulphate. As these oxidants are non-selective, the amount of oxidant required is initially assessed using bench-scale testing with site soil and groundwater. The American Society for Testing and Materials (ASTM) has developed a draft method for determining oxidant demand using potassium permanganate. However, no similar standard method exists for other oxidants. In this study, bench-scale oxidant demand test evaluation and oxidant demand testing of site soils have shown that the ASTM method is not suitable for other oxidants. In particular, oxidant demand testing using activated persulphate depends on several factors including persulphate concentration and contact time. Unlike the ASTM method that only measures aqueous permanganate concentration, soil analysis is recommended when performing oxidant demand testing with other oxidants to confirm contaminant oxidation has occurred at the given oxidant concentration(s) and within the test timeframe.

Andrew J. Daugulis1, Lars Rehmann1, George Prpich1,
and Ken Reimer2
1Department of Chemical Engineering, Queen’s University
2Environmental Sciences Group, Royal Military College of Canada

This presentation will outline the feasibility of a novel process concept for the remediation of soil contaminated with recalcitrant, hydrophobic compounds such as PAHs and PCBs. The proposed process consists of extraction of the target molecules from soil using carefully selected solid polymer beads, followed by biodegradation of the extracted contaminants in a solid-liquid two-phase partitioning bioreactor (TPPB). TPPBs are comprised of an aqueous phase containing an appropriate microbial catalyst, and a water-immiscible phase (the loaded polymer beads) that partitions the toxic/poorly water-soluble substrates, in response to maintaining thermodynamic equilibrium, into the aqueous phase at a rate determined by the microbial demand. Soil contaminated with approximately 3,000 mg/kg each of phenanthrene, fluoranthene and pyrene was contacted with the plastic Desmopan® (10% ratio), and resulted in >50% removal of each PAH in 48 h. The beads were subsequently added to a TPPB containing a PAH-degrading consortium, with extensive biodestruction of the PAHs. In an analogous study, Hytrel™ beads were used to extract Aroclor® 1242 from contaminated soil. Initial PCB levels of 100 mg kg–1 and 1,000 mg kg–1 could be reduced by > 50% after 48 h mixing at polymer-to-soil ratios of 1% (w/w) and 10% (w/w). It was further shown that Aroclor® 1242 could be delivered to the PCB degrading organism Burkholderia xenovorans LB400 in a 1 L solid liquid TPPB via Hytrel™ beads with a total of 70 mg PCB being degraded within 80 h of operation.

Barbara A. Zeeb1, Melissa Whitfield Åslund1, Ken Reimer1, Allison Rutter2
1 1Deptartment of Chemistry and Chemical Eng., Royal Military College of Canada
2 School of Environmental Studies, Queen’s University

PCBs, DDT, and other organochlorines (OCs) have long been considered unlikely candidates for any phytoremediation process. Due to their hydrophobic nature, these contaminants are expected to be strongly sorbed to soil particles, hence not taken up by roots or translocated within plants to any significant extent. However, recent work has identified plants in the species Cucurbita pepo ssp. pepo that are capable of accumulating levels of OCs from soils that greatly exceed modeled expectations. This indicates a potential to develop a type of phytoremediation, referred to as phytoextraction, as a remediation technique for OC-contaminated soils.

The objective of phytoextraction is for plants to accumulate significant amounts of a target contaminant from soil and store it in the plant shoot, which can then be harvested and treated as contaminated waste. This process still relies on traditional treatment methods such as incineration to deal with the harvested plant biomass, but it leaves the soil on site intact, and reduces the volume of contaminated solids for transport and treatment.

Studying the potential of this technology has been executed both in the greenhouse and at two contaminated field sites. The results confirm the ability of C. pepo species to take up higher than expected levels of OCs, even under realistic field conditions, and provide valuable information about the mechanisms of OC uptake and transfer in C. pepo. This research has also looked into the uptake potential of other plant species, including native colonizers. The results of these studies will be discussed, highlighting both contaminant- and site-specific results.

M. Kalin and W. N. Wheeler
Boojum Research Ltd

H.T. Odum coined the term “ecological engineering” in 1962, postulating that ecosystems contain a body of knowledge that, if decoded, could be applied constructively to waste management. Many abandoned mine wastes sites are extreme environments and contaminate surface and ground water, in spite of remediation efforts.

The hallmark of Boojum’s projects has been the decoding of these extreme environments and applying ecological engineering principles to mining waste ecosystems. Native biota can be encouraged to remove metals, acidity, alkalinity, and hardness, thereby stimulating biogeochemical precipitation processes. Periphyton and phytoplankton adsorb metals, and, as particulate matter settles to the sediment, provides the needed carbon to support bio-mineralization. Such supportive measures gradually lead to the reduction of contaminants in these extreme environments. On-going research on bio-mineralizing ecosystems is outlined.

Field demonstrations, applying the principles of ecological engineering to 30 projects implemented over 20 years in Canada and abroad, are presented and documented with 620 entries in the Mining Environment Research Literature Information Network (MERLIN) and are accessible through the Boojum web site (http://biblio. laurentian.ca/boojum) at the J.N. Desmarais Library at Laurentian University, Sudbury, Ontario. This database contains over 24,000 citations on the reclamation of mined lands.

Alexandre Boutin1, P.Eng., M.Sc.,
Sylvain Hains1, P.Eng., M.Sc.,
Christian Gosselin1, P.Eng., M.Ing.,
Denis Millette1, P.Eng., Ph.D.,
Mathieu Barbeau2, P.Eng., M.Sc.A.,
Bernard Michaud3, P.Eng.,
Stéphanie S. Leblond4
1 Golder Associates Ltd.
2 Golder Associates Innovative Applications Inc.
3 Ministry of National Defence
4 Defence Construction Canada

Golder Associates Ltd. and Golder Associates Innovative Applications Inc. (GAIA) were retained to implement at a National Defence site a nanoscale zero-valent iron (NZVI) reactive zone at pilot scale to control a TCE plume extending 4 km downgradient of three identified source zones. The dissolved plume consists mainly of dissolved concentrations of trichloroethene (TCE) with low concentrations of dichloroethene (DCE) and vinyl chloride (VC). The hydrostratigraphic setting consists of deltaic sand lying on proglacial sand. In 2006, successive injections of a total 4,000 kg of NZVI coated with a metallic catalyst were achieved. Right after the first mixture injection, the redox potential dropped under –400 mV. Three months after the injections, TCE concentrations had decreased over 80% from initial, but cis-DCE concentrations began to increase. A significant biological component was identified to contribute to the reduction in TCE concentrations. A complementary investigation program was undertaken in 2007 including: laboratory tests and DGGE analysis to assess the VOCs biological reduction potential; CPT profiling and optimization of treatment using dissolved hydrogen injection and groundwater re-circulation. Results will be presented including: 1) design of the injection; 2) transition of aerobic site conditions to anaerobic conditions; 3) evaluation of the rate of TCE reduction; 4) influence of biological reduction; and, 5) effectiveness of optimizing the treatment.

Charles W. Greer1, Elisabeth Lefrançois1, 2,
Ali Quoreshi3,
Damase Khasa4, Martin Fung5, Lyle G. Whyte2,
Sébastien Roy6
1National Research Council of Canada
2Department of Natural Resource Sciences, McGill University
3Symbiotech Research Inc.
4Centre de Recherche en Biologie Forestière, Université Laval
5Syncrude Canada Ltd.
6Département de Biologie, Université de Sherbrooke

that are distinguished from other treatment processes by the use of plants that are adapted to grow in saturated environments. While having the appearance of a wetland habitat, and employing many of the same biological processes found in natural wetland ecosystems, engineered wetlands are man-made systems that have been designed to emphasize specific characteristics of wetland ecosystems for improved treatment capacity. By leveraging proven engineering principles, the biological complexity of natural systems can be exploited to cope with diverse industrial waste streams.

Environmental compliance managers have a variety of remediation technologies to choose from; ranging from entirely passive, land-intensive wetland systems to very compact, energy-intensive mechanical treatment systems. In between these two ends of the spectrum, engineered wetlands are often employed. Engineered wetland reactors can be designed to allow for process control and to improve the overall treatment efficiency. Using treatment wetlands for groundwater remediation can be advantageous in a number of situations, including:

• Sites where mechanical treatment systems are at the end of their operational lifetime, or are operating at low removal efficiencies.

• Sites with DNAPL contaminants or extensive smear zones that will continue to generate contaminated groundwater for decades or even hundreds of years.

• Sites where the ability to trade land (larger footprint,
more passive system) vs. mechanical complexity is an
option.

The economics of wetland treatment systems can be summarized by the phrase “plants and bacteria work for free; people and machines don’t”. The economics of wetland treatment is most favorable for site managers who can trade space for mechanical complexity, and who must operate a treatment system over long periods of time. Depending on the type of contaminant, capital costs for wetland systems are typically less than their mechanical counterparts, with the real savings occurring due to less operating and maintenance costs.

This presentation will focus on various applications of treatment
wetlands, using the British Petroleum facility in Casper, Wyoming as a case study.

Scott Wallace1, Jim Higgins2
1Jacques Whitford NAWE
2Jacques Whitford Ltd.

that are distinguished from other treatment processes by the use of plants that are adapted to grow in saturated environments. While having the appearance of a wetland habitat, and employing many of the same biological processes found in natural wetland ecosystems, engineered wetlands are man-made systems that have been designed to emphasize specific characteristics of wetland ecosystems for improved treatment capacity. By leveraging proven engineering principles, the biological complexity of natural systems can be exploited to cope with diverse industrial waste streams.

Environmental compliance managers have a variety of remediation technologies to choose from; ranging from entirely passive, land-intensive wetland systems to very compact, energy-intensive mechanical treatment systems. In between these two ends of the spectrum, engineered wetlands are often employed. Engineered wetland reactors can be designed to allow for process control and to improve the overall treatment efficiency. Using treatment wetlands for groundwater remediation can be advantageous in a number of situations, including:

• Sites where mechanical treatment systems are at the end of their operational lifetime, or are operating at low removal efficiencies.

• Sites with DNAPL contaminants or extensive smear zones that will continue to generate contaminated groundwater for decades or even hundreds of years.

• Sites where the ability to trade land (larger footprint,
more passive system) vs. mechanical complexity is an
option.

The economics of wetland treatment systems can be summarized by the phrase “plants and bacteria work for free; people and machines don’t”. The economics of wetland treatment is most favorable for site managers who can trade space for mechanical complexity, and who must operate a treatment system over long periods of time. Depending on the type of contaminant, capital costs for wetland systems are typically less than their mechanical counterparts, with the real savings occurring due to less operating and maintenance costs.

This presentation will focus on various applications of treatment
wetlands, using the British Petroleum facility in Casper, Wyoming as a case study.