ASSESSMENT AND REMEDIATION OF CONTAMINATED SITES IN ARCTIC AND COLD CLIMATES

SESSION 1 - RISK ASSESSMENT AND SITE CHARACTERIZATION

New Challenges Associated with Risk Assessment of Contaminated Sites in Northern Environments

G.L. Robins, T.L. Knafla, and J.H. Sevigny

The use of risk assessment in the evaluation of potential health risks for humans and wildlife can be complicated by variables unique to northern environments. Pertinent variables include the close inter-relationship of first nations peoples with their environment, increased sensitivity to toxicants due to cold stress, hypothermic response to chemical exposure, effect of ice cover on winter surface water concentrations, and contaminant transport in discontinuous permafrost. The importance of these variables was highlighted while developing a risk management framework and conducting a risk assessment for a large oil and gas facility located in the Northwest Territories.

The determination of potential health effects is complicated by the fact that first nations populations are dependent on delicate northern food webs, and thus are sensitive to chemical impacts on their environment. This results in a substantial overlap between human and ecological risk assessments, which are risk concepts that are typically treated separately. The extreme seasonal variation in temperature is another variable of concern. Winter conditions place additional stress on animals and may influence their toxicological response to contaminants. Hypothermia is induced by several types of chemicals and could be fatal in cold winter months. Ice cover on surface water may increase concentrations of volatile hydrocarbons, leading to increased exposures for aquatic organisms. Permafrost conditions can influence subsurface contaminant transport. Prediction of contaminant transport in discontinuous permafrost can be difficult.

This paper identifies variables that present new challenges and areas of study for scientists developing risk management frameworks and conducting risk assessments for contaminated sites in northern environments.

Environmental Risk Evaluation for DEW Line Landfills

Wayne Ingham, Kenneth Reimer, Jennifer Rogers, Tanya Schulz, and Philippe Simon

The Distant Early Warning (DEW) Line located along the Arctic coastline was decommissioned in the early 1990s. The Canadian Department of National Defence (DND) is responsible for the cleanup of 21 DEW sites, which includes over 100 existing landfills. During discussions with the Inuit, a requirement for a consistent method of evaluating the potential environmental risk associated with existing landfills was identified. The evaluation process was to provide consideration for the uniqueness of the Arctic ecosystem. Through the joint effort of representatives of DND and Nunavut Tunngavik Incorporated (NTI), a landfill risk evaluation matrix was developed. In this paper, the development of the matrix, the resulting landfill environmental classifications, and proposed remediation solutions are described. The matrix is compared to similar evaluation systems. The use of this matrix, as a screening tool, has assisted in developing consensus between the various stakeholders on the proposed landfill remediation solutions.

DEW Line Landfill Risk Evaluation - A Case Study

Wayne Ingham, Kenneth Reimer, Jennifer Rogers, Tanya Schulz, Philippe Simon, and Shelia Street

The Distant Early Warning (DEW) Line located along the Arctic coastline was decommissioned in the early 1990s. The Department of National Defence (DND) is responsible for the cleanup of 21 DEW sites. During discussions with Nunavut Tunngavik Incorporated (NTI), a requirement for a consistent method of evaluating the potential environmental risk associated with existing landfills was identified. The evaluation process was to provide consideration for the uniqueness of the Arctic ecosystem. Through the joint effort of representatives of DND and NTI, a landfill risk evaluation matrix was developed. In this presentation, the matrix is applied to the DEW Line landfills located at Cambridge Bay (CAM-M), Nunavut. The scoring of each category, and the resulting landfill environmental classification, will be described. The proposed remediation solution is currently being applied and will be discussed. The use of this matrix, as a screening tool, has assisted in developing consensus between the various stakeholders on the proposed remediation solutions.

An Integrated Approach to Site Investigations in Permafrost Regions: Geophysics, Soils, Groundwater, and Geographical Information Systems

Richard Kellett, Jon Fennell, Ann Glatiotis, Wes MacLeod, and Catherine Watson

The abandonment and restoration of major facilities in northern regions requires a unique approach to site characterization because of the complexity of the terrain and geological environment. Near surface conditions include continuous and discontinuous permafrost, a thin, seasonally active layer, and shallow bedrock. Geophysics, soil sampling, and hydrogeological investigations are used as primary tools for acquiring information about a site. Geographical Information Systems are employed as platforms for assimilating and viewing the data. Geophysical methods have proven useful in mapping the depth and thickness of permafrost and the distribution of inorganic contaminants in soil and groundwater. Buried metal (e.g. in landfills) can also be located accurately with ground and airborne geophysics. Soil sampling boreholes and groundwater monitoring wells are positioned more effectively using geophysical anomalies as targets. Soils and groundwater investigations focus on organic, inorganic, and metals contaminants in the near surface active zone where permafrost has been degraded or is intermittent. Mapping and managing large northern sites, with oil field and military facilities, requires extensive site investigations and efficient data handling which is most easily accomplished using an integrated system.

Preliminary Engineering on the Cleanup of Waste Disposal Sites in Iqaluit, Capital of the Nunavut Territory

Ken Johnson

The Town of Iqaluit has had a continuing problem with solid waste management within the community. This problem began with the use of multiple solid waste disposal sites by various military groups in the 1950s and 1960s. The use of the military dump sites, and additional unorganised sites by the community continued after the military departure. The end result has been a total of six known community solid waste disposal sites, none of which have incorporated proper waste management techniques or proper site reclamation.

UMA Engineering Ltd. was retained by the Town in 1991 to provide preliminary engineering for the cleanup of five solid waste disposal sites within the community. The objectives of the preliminary engineering included physical site assessments and documentation, outlining reconnaissance testing, and outlining a framework within which to prepare and implement cleanup plans.

Flare Pit Waste in Western Canada: A Characterization Mechanism to Enhance Flare Pit Sludge Remediation Efficiency

Jennifer G. Speer

Flare pit sludge is present throughout the oil and gas production areas of Canada. The sites represent varying degrees of liability due to the presence of metals, salts and hydrocarbons. Efforts are underway to remediate flare pit sites, in response to regulatory changes.

To recommend efficient remediation methods for flare pit sludge, thorough sludge characterization must first take place. A database of physical, chemical and historical characteristics of 436 flare pit sites mostly in Alberta was prepared. Chemical parameters in the database were compared to existing remediation criteria. The sites were categorized according to their concentrations of each chemical parameter. The categories were compared to historical site details.

Nine possible site categories were determined, six of which are significant for the database, all of which are based on remediation consideration. Higher degrees of contamination were associated with gas production, sour fluid production, well sites and day soil.

Cleanup of PCB Contaminated Soil at Saglek, Labrador

K.J. Reimer, Z.A. Kuzyk, C.C. Knowlton, J.P. Stow, and J.D. Boissonneault

The Environmental Sciences Group, as scientific advisor to the Department of National Defence, is currently overseeing the environmental cleanup of polychlorinated biphenyl (PCB) contaminated soils at Saglek, Labrador. Saglek has been the site of military operations since the 1950s, initially as a Pole Vault station (dismantled in the late 1980s), and presently as a modern long range radar facility of the North Warning System (NWS).

In 1996, a comprehensive assessment identified three areas of PCB contaminated soil at the site, one in close proximity to the marine environment of Saglek Bay. Cleanup activities were undertaken in 1997 and, to date, have resulted in the excavation of over 20,000 m³ of soil contaminated with over 50 ppm PCBs. A remediation contractor (chosen early in 1999) will be on site in the summer of 2000 to commence treatment of excavated soil.

Concurrent with cleanup of the contaminated soil, investigations have been conducted to determine the impact of this land based contamination on the marine ecosystem of Saglek Bay. Studies have been designed to both delineate the spatial extent of PCB contamination in Saglek Bay and to gain an understanding of the impact of this contamination on the local food web. A priority of the investigation has been to address concerns about the impact of the local source contamination on traditional food resources. To this end, investigations have been jointly designed and carried out with the Labrador Inuit Association.

The results of these investigations, combined in an ecological risk assessment (ERA) framework, will provide a scientific basis for making decisions regarding the management of the contaminated sediment. A geographical information system (GIS) will allow the spatial modelling of the contamination and will assist with the communication of risk information to varied audiences.

The project has received widespread support from regulating agencies at both federal and provincial levels as well as the endorsement of the Labrador Inuit Association. Such support, essential for the success of any project, has come as a result of regular and ongoing communications with all stakeholders and the concerned members of the Labrador community. Details of the risk communication strategy used at Saglek will also be discussed.

SESSION 2 - CONTAMINANT MIGRATION IN PERMAFROST

The Behaviour of Petroleum Spills in Permafrost Soils

K.W. Gibbar and M. Nahir

In the past, it has generally been assumed that spills of hydrocarbons onto permafrost soils will not migrate into the frozen soil, i.e. that the frozen soil provides an impermeable barrier. There is becoming an increasing body of evidence showing that this is not necessarily the case. Laboratory and field investigations of the migration of non-aqueous phase liquids (NAPLs) into frozen soils shows that in the presence of air voids within the frozen soil matrix, gravity driven downward flow in evident. Further, capillary suction laterally into small fissures is another potential mechanism of migration of these petroleum compounds. This paper will review the current body of evidence general.

Although the understanding of the fate and behaviour of contaminants in thawed soils has continued to advance, there has been little research to date examining their behaviour in permafrost and frozen soils. It has generally been assumed that the frozen soil acts as an impermeable barrier but there is now evidence indicating that this is not necessarily so. With increasing development in the North, much of which is driven by the petroleum and mining industry, there has been an increasing level of interest in the behaviour of contaminants in frozen soil. This paper will review the results of research on the migration of petroleum hydrocarbons into permafrost and frozen soils.

There are a number of physical phenomena that may be responsible for migration of these contaminants. It is well known that a portion of the pore water in permafrost may be unfrozen, which may allow it to act as conduit for contaminant migration. Further, fill installed for construction pads is often unsaturated, so a network of continuous air voids may act as a conduit for contaminant migration. Also, frozen soil subject to decreasing temperatures will undergo thermal contraction, which may lead to the development of a network of fissures. This is most evident in the upper regions where temperature changes are the most extreme. Free phase petroleum hydrocarbons may migrate through these fissures due to gravity drainage or capillary suction. It is desirable therefore, to examine each of these mechanisms and their potential impact.

Behaviour Mineral and Organic Contaminants in Permafrost

E.M. Chuvilin, N.S. Naletova, and E.M. Miklyaeva

Polar regions development can cause serious ecological problems related to mineral and organic pollutants spreading in lateral and vertical directions. Preferable direction and intensity of pollution migration is determined by the pollutant type, frozen rock and soil structure and composition, time of interaction and temperature conditions. The difference in behaviour of soluble and insoluble mineral and organic pollutants in permafrost has been studied. In particular, it was established, that ice-bearing soils are permeable for different salts water solutions (including metals and radioactive elements), but, in the same time, they can be impermeable for organic water-insoluble compounds (oil and oil-based products). Data received allow estimation of the properties of permafrost soils when storage for mineral and organic compounds are designed.

Solute Migration From Abandoned Drilling Mud Sumps, Mackenzie Delta Area, NWT

L.D. Dyke

Oil and gas exploration in frontier arctic regions has relied on ice-bonded permafrost as a medium for containing waste fluids from drilling operations. Drilling mud is placed in pits (sumps) excavated in permafrost and covered once the contents are partially or completely frozen. However, the performance of permafrost as a continuing medium for these wastes has not been verified. If drilling fluids or other wastes are to be routinely disposed of in permafrost settings, the true suitability of permafrost as a waste repository needs to be determined. Although the hydraulic conductivity of well ice-bonded permafrost may be low, it can be greatly be increased depending on textural or environmental factors. Permafrost may be dry or it may contain appreciable amounts of unfrozen water. It may contain an ice fabric, which when warmed by disturbance or climate change, greatly increases hydraulic conductivity. Thawing ice fabric in the active layer can produce the same effect. These factors suggest that contaminant movement in frozen and thawing ground should be examined to gain a better indication of the suitability of permafrost sites for waste disposal.

Although existing drilling mud disposal sites in the Mackenzie Delta area pose no immediate environmental threat, they offer a unique opportunity for examining the effectiveness with which contaminants have been contained by ice-bonded sediments. Preliminary assessments of five sumps show that potassium chloride, present in muds as a freezing point depressant, is migrating away from sumps through the active layer to distances of tens of metres on level ground and hundreds of metres on sloping ground. It has also moved into ice-bonded permafrost sediments. Diffusion, solute exclusion ahead of freezing fronts, and advection where sumps are located on slopes, are the presumed causes of solute migration. These results suggest that neither permafrost nor fine-grained thawing sediments can be expected to completely contain contaminants.

Hydraulic Properties of Hydrocarbon Contaminated Permafrost Affected Soils

T.L. White

The thermodynamic conditions within the seasonal frozen active layer overlying permafrost and within perennially frozen ground are such that there is translocation of water and ice and the displacement of soil particles. The existence of unfrozen water along with ice at temperatures below 0°C is the result of both capillary and mineral surface forces, which are responsible for the unique thermal, mechanical and hydraulic properties. The introduction of immiscible hydrocarbon contaminants such as diesel fuel, gasoline, naphtha and aviation fuel into this dynamic porous medium results in micro structural changes that take place as a function of both cryogenic process and contaminant concentration. Micro morphological observations revealed evidence of reorganization of silt and clay micro fabric with changes in aggregation of particles and inter-aggregate porosity in a Regosolic Turbic Cryosol. Marked differences in morphology have developed in this cryosol occurring in the active layer compared to those in permafrost situated beneath the site of a decommissioned refinery in the NWT. Morphological observations of the active layer indicate that a tighter packing of particles into aggregates and greater spacing between aggregates takes place after exposure to hydrocarbon concentration ranging between 50 - 130 ppm. When hydrocarbon concentration exceeds 4,000 ppm, decreases in inter-aggregate porosity for the Regosolic Turbic Cryosol situated in the active layer, occur. The inter-aggregate porosity (between aggregates) of the soil fabric decreased from 35% (uncontaminated) down to porosities ranging between 10-15% in response to consolidation. Changes in porosity resulted in significant decreases (two orders of magnitude) in the hydraulic conductivity 2.0 x 10^-4cm s^-1 (uncontaminated) to 1.38 to 9.4 x 10^-6cm s^-1 (contaminated) was observed to occur in the cryosols exposed to hydrocarbon concentrations exceeding 4,000 ppm.

Scanning electron micrography revealed that the physical structure of the identified clay mineral illite has been altered by the hydrocarbons. Micrographs of this clay mineral lattice reveal how they have begun to slake (disintegrate). The illite present in sediments in the permafrost, however, do not show any evidence of this type of disintegration. It can be hypothesized that in the active layer, the illite is subjected to the additional effects of freeze-thaw cycles and chemical and biological alteration. The interparticle porosity of the Regosolic Cryosols in the permafrost was observed to increase when hydrocarbon concentrations between 4,000 to 18,000 ppm were observed. The absence of seasonal freeze-thaw cycles and weathering agents at depth in the permafrost has apparently precluded the effects of consolidation associated with these cryogenic processes present in the active layer. This, however, would apply only to epigenetic and not to syngenetic permafrost; the latter would have been subjected to many freeze-thaw cycles as it developed. Permafrost affected sediments at depth ranging between 1.2 to 3.65 m below surface were observed to have frozen hydraulic conductivity values of 4.28 x 10^-11cm s^-1 (uncontaminated) and values ranging between 4.86 to 6.95 x 10^-10cm s^-1 (contaminated) for hydrocarbon concentrations exceeding 4,000 ppm.

SESSION 3 - MINING CONTAMINATION AND CLEANUP

Environmental Assessment and Remediation of Abandoned Mines in the Yukon Territory

Tim Sackmann and Michael Nahir

A program to conduct environmental assessments of abandoned mine sites was completed to identify acid generation potential, human health and safety risks, inventory non-hazardous and hazardous wastes, and characterize on-site soil and water contaminants. This paper describes the objectives established and methods used in evaluating abandoned mine sites for further assessment and possible remediation. A priority ranking scheme was established to define high, medium, and low priority sites, as well as those requiring no further work.

Field investigations of forty-nine abandoned mines identified ten high priority sites requiring action to remediate or manage health and safety, environmental, and aesthetic concerns. Thirty-three abandoned mine sites were designated as a medium or low priorities for remedial action. Six sites presented an insignificant risk to humans and the environment and did not require any further assessment or remedial work.

Case Study: Rehabilitation of Mine Tailings at the Venus Mine Mill Site Near Carcross, Yukon Territory

Henry Westermann and Michael Nahir

Venus Mine site is located in the Yukon Territories along the South Klondike Highway, approximately 22 km south of the community of Carcross. In the early 1970s, a mill was constructed approximately 2 kilometres north of the Venus Mine site. Tailings from the mill were placed in a small natural depression on the shore of the Windy Arm of Tagish Lake. To accommodate more tailings the natural depression was augmented by perimeter berms constructed of uncompacted natural granular material. The mine operated for only a few years and the mill has since been dismantled, leaving the tailings impoundment on the shore of Tagish Lake in full view of the highway.

In addition to its proximity to the lake, the tailings are located below the highway in a historical slide area and are subject to seasonal flooding by surface runoff as well as year round discharge from a groundwater collection system installed under the highway.

The tailings were assessed and were found to contain a number of heavy metals of environmental concern including arsenic, cadmium, lead, zinc and to a lesser extent copper and as well as being net acid generating and in the early stages of Acid Rock Drainage (ARD). Both the lake and surrounding vegetation were being negatively impacted by the tailings through wind and water erosion. Tailings were being eroded by water directly into the adjacent lake and were being distributed by wind erosion and impacting both the surrounding vegetation and the lake itself.

This paper will discuss how the tailings were impounded and submerged using a unique design incorporating a sheet pile wall and a multi-layered cap. The sheet pile wall was installed along two sides of the natural depression to contain the tailings and the cap was constructed to control physical erosion of the tailings while allowing the continuous flow of the surfaced groundwater to flood the tailings for ARD control and then drain from the cap with minimal contaminant levels.

The paper also discusses difficulties encountered in the construction phase of the project due to saturated conditions.

AMD Generation at Sub-Zero Temperatures

R.C. Godwaldt, K.W. Biggar, and D.C. Sego

This paper discusses several factors which may affect the long-term integrity of structures constructed from frozen sulfidic material given the exothermic nature of the sulphide oxidation and the predicted ongoing oxidation of sulfides in sub-zero temperatures. The exothermic nature of the sulphide oxidation reactions may lead to the development of microclimates within the structure, leading to the creation of unfrozen water zones. Although the chemistry and kinetics of AMD generation are well understood at moderate temperatures, few studies have explored the process at sub-zero temperatures. Part I of this paper examines microbiological activity and oxygen availability as factors affecting AMD, in addition to unfrozen water content, solute redistribution and freezing point depression which become key elements in sub-zero biologically mediated AMD characterization. This establishes the foundation for Part II, a description of research in progress for a series of humidity and static batch tests aimed at tracking the effects of temperature on acid generation, from +20°C to -20°.

SESSION 4 - BIOREMEDIATION ASSESSMENT

Biodegradation of Petroleum Hydrocarbons at Low Temperatures

Lyle G. Whyte and Charles W. Greer

In sub-Arctic and Arctic regions, petroleum hydrocarbon contamination of soil and water has occurred at former and active military bases, and at other sites where the petroleum industry is actively exploiting extensive northern oil reserves. The use of conventional physiochemical technologies for treating these sites is very costly because of their remoteness and unique character. Bioremediation of contaminated Arctic sites has also been proposed as a cleanup technology because it may be the most logistically and economically favourable solution, although it is technically difficult. The biodegradation of pollutants is inhibited by below freezing temperatures for much of the year while natural rates of biodegradation during the above-freezing summer months are generally too low to rapidly remove hydrocarbon contaminants. Nevertheless, biodegradation of many of the components of petroleum hydrocarbons has been observed at low temperatures in a wide variety of hydrocarbon-contaminated sites. The observed biodegradation is the result of indigenous psychrophilic and psychrotrophic micro organisms which are characterized by low temperature growth ranges of <0°C to 15-20°C and <0°C to 30-35°C, respectively. In the present study, the abilities and characteristics of several hydrocarbon degradative psychrotrophic bacteria examined in our laboratory will be reviewed. Examples will be given of bioaugmentation with specific cold-adapted organisms or indigenous degradative consortia and/or biostimulation with nutrient amendments (commercial fertilizers) for enhancing degradation of specific contaminants in soils from northern Canada, including the Arctic. These examples will also describe the application of molecular techniques such as PCR and gene probing for analyzing and monitoring degradative micro organisms in contaminated soils.

An Evaluation of the Bioremediation Potential of Near Surface Groundwater Contaminated with Petroleum Hydrocarbons in the Yukon

M.E. Billowits, L.G. Whyte, J.A. Ramsay, C. Greer, and M. Nahir

This paper presents the results of two separate studies relating to the assessment of the bioremediation potential for the in situ restoration of petroleum contaminated soil and groundwater at an abandoned oil refinery in Haines Junction, Yukon and at the Whitehorse International Airport in Whitehorse, Yukon. The bioremediation of contaminated soil and groundwater by naturally occurring, cold adapted (psychrotrphic) micro organisms is of particular interest since it demonstrates that microbial degradation of the hydrocarbons can occur at aquifer ambient temperatures in northern climates. The work has involved a detailed site assessment and a chemical/microbiological characterization at each site. Various microbiological and molecular biological techniques were used to illustrate that a viable psychrotrophic hydrocarbon degrading population occurs within each aquifer system. Results have shown that higher levels of pyschrotrophic than mesophilic bacteria occur in the aquifer material, indicating that a cold adapted population occurs. DNA testing was used to illustrate that psychrotrophic bacteria containing genes similar to alkB, which is involved in alkane degradation, was present within the aquifer material. A hydrodynamic soil column system and various soil and groundwater microcosm tests were used to determine if the naturally occurring bacteria were capable of mineralising the organic contaminants at 5°C. The soil column study demonstrated the relative extent of degradation which could be attributable to various in situ treatment scenarios. Although at slow metabolic rates, the microcosm tests demonstrated the mineralization of various organic contaminants similar to those contaminants encountered in the actual impacted groundwater setting. The results of the study demonstrate that an in situ biostimulation with nutrient amendment or an intrinsic bioremediation treatment technique may be feasible for the restoration of each contaminated groundwater system at ambient temperatures.

Initial Assessment of Intrinsic and Assisted Bioremediation Potential for Diesel Fuel Impacted Soils at Eureka, NWT

J. Jeffrey Wilson, Brett Yeske, and Douglas Lee

A laboratory scale treatability study was performed on diesel fuel impacted soil samples from Eureka, NWT. The experimental design used two soil columns prepared to simulate in situ conditions for assessing intrinsic or enhanced in situ bioremediation, and two soil jars that were mixed periodically to simulate the ex situ land treatment bioremediation option. Each test was monitored by soil respiration using dedicated oxygen sensors with a data logger. In the absence of passive soil aeration, only iron was present in sufficient concentration to provide adequate reducing equivalents to support intrinsic bioremediation by the indigenous soil bacteria. The results strongly suggest that bioremediation at the Eureka site will be possible. GC/FID analysis confirmed approximately 31% TEH reduction for both aerobic and anaerobic bioremediation conditions after 125 days at 5°C. The nitrogen amended column test indicated that in situ bioremediation using a periodic addition of water soluble nitrogen fertilizer simulated the bioremediation rate.

Bioremediation of Hydrocarbon Contaminated Arctic Soils

M. Allen, K.J. Reimer, and W.W. Mohn

Fuel spills resulting from activities at military and industrial sites in Canada’s Arctic have been shown to significantly impact fragile Arctic ecosystems. Such fuel spills may arise from the transport and storage of any combination of diesel, jet fuel, gasoline and lube oils.

This paper will discuss the use of engineered above ground biopiles for hydrocarbon bioremediation. This technology proved to be ideal for dealing with the challenges of harsh climates and remote locations, and was optimized to provide a simple, low cost remediation solution. Biopiles allow for the complete degradation of organic compounds, reducing contaminants to carbon dioxide, water and biomass. This research evaluated various requirements for the optimization of the degradation process including fertilizers, aeration and heating systems, and microbial enrichment (using indigenous micro organisms). Results showed that, with the use of biopile systems, bioremediation rates and extent of total petroleum hydrocarbon (TPH) removal were significantly increased and that soil and amendment characteristics were key performance factors. Low nitrogen and phosphate levels in the soil limited TPH biodegradation while fertilizer and inoculum addition significantly increased TPH removal (approx. 75% in less than 50 days). It is hoped that this initial work and ongoing aeration system optimization will lead to the development of a standard operating procedure for the treatment of hydrocarbon contaminated soils at northern sites.

Examples will be given from work conducted at several northern sites since 1996 including the DEW Line site at Komakuk Beach, Yukon, the North Warning System radar sites at Cambridge Bay on Victoria Island and at Hall Beach on the Melville Peninsula, Nunavut as well as CFS Alert, Nunavut.

Intrinsic Bioremediation of BTEX in a Cold Temperature Environment

Christopher Johns, Kevin Biggar, Julia Foght, and Anjum Mullick

This research project involves application of the intrinsic bioremediation methodology to cold temperature sites contaminated with petroleum hydrocarbons. Benzene, toluene, ethyl benzene, and xylene (BTEX) contamination is confined to near surface sand beds or lenses within a thick glacial till deposit. A site investigation was carried out to delineate stratigraphy, hydrogeology, microbiological setting, contaminant levels and geochemical conditions at each site. An assessment of the terminal electron accepting processes (TEAPs) was undertaken. Results provide evidence for aerobic activity at the plume fringe, and iron reduction, sulfate reduction and methanogenesis within each plume. Enumeration of contaminant degrading micro organisms was completed through the Most Probable Number (MPN) technique indicating viable populations of aerobic petroleum degraders, nitrate reducers and iron reducing bacteria. A laboratory experimental program investigated the effects of cold temperatures on the rate and extent of substrate utilization. Preliminary results indicate that both sites are suitable candidates for intrinsic bioremediation and that significant rates of biodegradation are possible at low temperatures.

Intrinsic Bioremediation of Chlorinated Hydrocarbons at Cold Temperatures

Anjum Mullick, Dr. K.W. Biggar, Dr. Julia Foght, and Chris Johns

Several contaminated sites in the United States have been evaluated for intrinsic bioremediation, but its application in colder temperatures has not been well addressed. The viability of intrinsic bioremediation of chlorinated aromatic hydrocarbons at cold temperatures was studied. Intrinsic bioremediation has been proposed for a site approximately 300 km northeast of Edmonton, Alberta. The site is a former landfill that was also used for disposing of various hydrocarbon based products such as oils, solvents and degreasers. Downgradient of the landfill, compounds of environmental concern that have been detected include benzene, toluene, xylenes, ethyl benzene (BTEX), phenols, 1,1,1-trichloroethane, 1,1-dichloroethane and dichlorobenzenes. The research undertaken involves four separate phases: 1) site investigation; 2) analysis of contaminant concentrations and terminal electron accepting processes across the site; 3) laboratory microbial study; and 4) computer fate and transport modelling. The primary focus of the laboratory study is to investigate how cold temperatures affect the rate of reductive dechlorination. Traditionally, bioremediation rate studies are carried out at ambient temperature (20 to 22°C). Rates at other temperatures are then extrapolated based on the Q10 rule applied to ambient temperature tests. The batch tests in this study will be performed at 8 and 22°C to determine if the in situ micro organisms are sufficiently acclimated to the cold temperatures and therefore would exceed the biological activity otherwise predicted by the Q10 rule. Initial results from the geochemical investigation and Most Probable Number (MPN) studies suggest that in the least, reductive dechlorination can and is proceeding at cold temperatures.

Temperature Effect on Bioremediation of Diesel Fuel Contaminated Clay

A.G. Man and D.M. McCartney

A biotreatability study was conducted to determine the effect of temperature on the bioremediation kinetics of a diesel fuel contaminated heavy clay soil under simulated landfarming conditions. Biodegradation was measured in soil microcosms by monitoring headspace oxygen concentration and ¹⁴CO₂ evolution from the mineralization of ¹⁴C-octadecane. Microcosms were run in triplicate at temperatures of 3, 10, 16, and 22°C. The maximum biodegradation rates, calculated from oxygen consumption on a tetradecane (n-C₁₄) equivalent basis, were found to range from 0.13 mg kg^-1day^-1 at 3°C to 9.8 mg  kg^-1day^-1 at 22°C. The Arrhenius temperature coefficient was found to be 1.19.

The diesel range n-alkanes remaining in the soil at the end of the experiment were analyzed by gas chromatography (GC/FID) and compared to fresh unweathered standards to determine the effect of temperature on the final hydrocarbon depletion. Relative chromatographic response of the n-alkanes (G₁₀ to C_18’ inclusive) from biologically active, abiotic and fresh unweathered soil samples indicated that abiotic losses increased at higher temperatures, as expected. This limited the total amount of hydrocarbons available for biodegradation at the higher end of the treatment range examined. The maximum amount of biological depletion was observed at 10°C for the C₁₀ to C₁₈ carbon range. The reduced abiotic losses at the lower temperatures was off-set by increased biodegradation over the time frame of the experiment. This resulted in similar total n-alkane depletion over the 10°C to 22°C temperature range. This suggests that overall n-alkane depletion may be expected to be similar regardless of temperature as long as the landfarming operation takes place in the 10°C to 22°C range.

Microbial Population and Activity Responses to Fertilization of Petroleum Hydrocarbon Contaminated Soils Near Barrow, Alaska

Joan F. Braddock and James L. Walworth

The objectives of this field scale study were to (1) test a simple bioremediation treatment strategy in the Arctic, (2) examine the effect of fertilization on microbial populations and activity, and (3) monitor the effect of fertilization on the persistence of aliphatic versus aromatic hydrocarbons. The site is a coarse sand pad near Barrow, Alaska that once supported fuel storage tanks. Previous to this field scale study we conducted a treatability study for the site (Braddock et.al. 1997). In small macrocosms (each containing about 20 kg of soil) incubated in situ, water soluble fertilizer was added to provide levels of nitrogen:phosphorous of 100:45, 200:90, or 300:135 mg/kg soil. Microbial activity and populations were stimulated relative to controls, but the stimulation was inversely related to the added concentration of fertilizer. The pad material has little water-holding capacity and fertilizer addition at the highest level (300 mg/kg N) led to substantial decreases in soil-water potential and concomitant decreases in microbial activity. For the field study, in addition to examining the overall effectiveness of fertilizer addition on hydrocarbon degradation on a larger scale, we wanted to examine if there were any differential effects of fertilizer addition on losses of aliphatic versus aromatic hydrocarbons. Fertilizer additions have been reported to enhance, inhibit or have no effect on the mineralization of various fractions of hydrocarbons in a number of laboratory studies.

Diesel range organics at the beginning of the study ranged from 250-860 mg/kg soil. The course sand at the site is characterized by low organic carbon (<1%) and soil moisture (1-3%) contents. Replicate field plots were treated with fertilizer to yield final concentrations of 0, 50, 100 or 200 mg N/kg soil. These values were selected because addition of 100 mg N/kg soil was found to enhance microbial populations and activity in the treatability study. Soil samples were collected three times during the thaw season and analyzed for physical and chemical properties, microbial populations and activities, and concentrations of semi-volatile hydrocarbons.

Soil pH and soil-water potentials declined as a result of fertilizer application. Addition of fertilizer significantly increased soil respiration potentials but, in contrast to the treatability study, not the populations of micro organisms measured (total heterotrophs, gasoline degraders and diesel degraders). Hydrocarbon concentrations decreased during the course of the experiment. The sum of concentrations of aromatic hydrocarbons measured declined in all surface soils, including reference plots, from the concentrations at the start of the experiment, but only decreases in the subsurface were significantly greater in the fertilized than the unfertilized soils. This indicates volatilization as a mechanism for loss of aromatic hydrocarbons from the surface soil and nutrient-stimulated biotic degradation processes in the subsurface soil. In contrast, both surface and subsurface aliphatic loss was enhanced by fertilizer addition. Losses of liner alkanes were more strongly affected by fertilization than were losses of branched alkanes, also suggesting that biological processes were important in degradation at this site. Even at this cold, dry arctic site, biological processes were effective in removing both aromatic and aliphatic hydrocarbons from these soils. The results of this study have recently been accepted for publication (Braddock et.al., In Press).

SESSION 5 - BIOREMEDIATION CAST STUDIES

In Situ Bioremediation of a Hydrocarbon-Contaminated Pond at Hall Beach, NWT

Robert Eno, Jennifer Rogers, Jean Heroux, and Dr. Ken Reimer

A shallow pond near the Northwest Territories Power Corporation’s (NTPC) plant in Hall Beach, NT, is contaminated with fuel as a result of several decades of chronic fuel spills from a former tank farm. As the pond is located in the centre of town and the fuel contamination is not migrating off-site, RWED felt that this presented an ideal opportunity to conduct experiments in order to determine the feasibility of employing in situ bioremediation to clean up fuel spills in the Arctic.

Following baseline sampling in 1994, a number of lab and pilot scale bioremediation experiments were conducted. Initial attempts at stimulating anaerobic microbial biodegradation were unsuccessful. Lab experiments conducted during the winter of 1996 indicated that aerobic microbial biodegradation will occur at low temperatures given the right amount of nutrients and oxygen. In September 1997, a commercial floating aerator was installed in the most contaminated section of the pond and operated for three weeks. The aerator was re-installed the following year, 1998, and operated through the summer. Water samples were collected at regular intervals over the 12 week period. The results of the study will provide an indication of the effectiveness of in situ bioremediation as a means of cleaning up fuel spills in the Arctic.

The Economics of Thermally Enhanced Bioventing of Petroleum Hydrocarbons in Cold Regions

Dennis M. Filler and Robert F. Carlson

Bioventing with soil warming was performed at a Fairbanks, Alaska, UST site contaminated with petroleum hydrocarbons. Thermal enhancement techniques were compared for bioremedial and cost effectiveness. Project objectives included (1) developing thermal insulation systems (TIS) that afford year round bioventing of petroleum contaminated soils, (2) modelling the thermal regime of three treatment areas, (3) relating monitoring and analytical data to treatability, and (4) establishing costs for implementation at future sites. Thermally enhanced bioventing was cost effective in remediating the petroleum contaminated vadose zone at a subarctic site within two years. The remedial cost for active treatment of 4,587 m³ (6,000 cubic yards (cy)) of soil with a maximum total petroleum hydrocarbon (TPH) contaminant level of 2,400 mg/kg was US $26.08 per m³ (US $19.91 per cy). This paper summarizes the case study and presents an economic analysis of TIS materials for use with future bioventing and soil vapour extraction treatments.

Bioremediation of Hydrocarbon Contaminated Sites in Northern Regions: A Synthesis of Full-Scale Projects

Yvan Pouliot and Jean-Luc Sansregret

Biogénie, a firm specialized in site remediation, primarily working in eastern Canada and Europe, has developed technology designed to decontaminate soil in northern climates. This technology, based on a proprietary process of contaminant biodegradation, has been applied to more than 20 different sites located in northern regions (James Bay, Ungava Bay, Hudson Strait and Gulf of St. Lawrence) or has been operated under winter conditions. These projects, carried out since 1991, have addressed sites of various sizes (80 to 90,000 tons), have handled different working conditions (no roadways, no electricity, etc.), numerous types of sites (former diesel generator stations, pipeline spills, petroleum depots, lagoon sludge, etc.) and involved a number of different contaminants (fuel, used oil, transformer oil, bunker, etc.). An overview of these projects, as well as the results obtained, is covered in this paper.

SESSION 6 - REMEDIATION TECHNOLOGIES AND TECHNIQUES

In Situ Chemical Oxidation of Trichloroethlene Using Potassium Permanganate

Daniel J. McKay

A full scale demonstration of in situ chemical oxidation using a solution of potassium permanganate is in the final stage of preparation at the US Army Cold Regions Research and Engineering Laboratory (Hanover, New Hampshire). Current efforts are focused on treating immiscible-phase trichloroethylene (TCE) in the unsaturated zone between 4 and 10 m below the ground surface. The water table is approximately 40 m below the surface. The lacustrine formation is predominately silt with discontinuous distributions of clay bedding as well as fine sands. The low permeability clay lenses are nearly saturated with water and also contain the highest measured concentrations of TCE (up to 6% w/w). Air-based remediation methods were thus deemed to be of limited utility because of restrictive capillary effects.

The permanganate solution is to be delivered to the target zones in 1.5 m increments of depth through an array of 5.1 cm diameter well screens placed inside 7.6 cm boreholes. Each well screen is 1.5 m long and isolated above by an inflatable borehole packer that enables delivery of the oxidant under pressure. A 1.5% solution is to be prepared in an automated batch mixing plant with a capacity of 20,000 L of permanganate. The oxidant will then be transferred to two automated distribution buildings, each designed to deliver 10,000 L/day to the contaminated soil through a system of 32 (total) injection points.

Prior to construction, the contaminant at each injection location was characterized through continuous profile sampling using direct push techniques. Post-treatment performance is to be monitored by collection of soil samples near the injection point and by collection of pore water samples at selected locations. Chemical analyses include determinations of TCE, manganese, potassium, chloride, pH, alkalinity, and cation exchange capacity. Physical analyses consist of measurements to establish stratigraphic profiles and quantify changes to soil permeability.

Plant-Based Treatment of Organics Contaminated Soils in Cold Climates

C.M. Reynolds, L.B. Perry, C.S. Zpidgeon, B.A. Koenen, D.K. Pelton, and K.L. Foley

We have demonstrated statistically improved contaminated soil treatment using rhizosphere enhancement. Rhizosphere enhanced biotreatment is applicable to many remote or permafrost sites and is inexpensive to implement and maintain. In a 26 week laboratory study, winter rye (Secale cerealeL.) increased removal of pyrene relative to a control. In a field study in Fairbanks, Alaska, a mixture of annual ryegrass (Lolium multiflorum, Lam.) and red fescue (Festuca rubra, L.) with nutrient amendments was compared to a control treatment. After 34 weeks of treatment, diesel TPH levels decreased from approximately 8,400 mg/kg to 2,500 mg/kg and 700 mg/kg for the control and rhizosphere treatments, respectively, and crude oil TPH levels decreased from approximately 6,100 mg/kg to 4,000 mg/kg and 3,400 mg/kg for the controls and rhizosphere plus nutrients, respectively. These data demonstrate that rhizosphere treatment can be cost effective strategy, particularly suited for treating sites that are remote or in cold regions.

In Situ Remediation of Shallow Groundwater Aquifer Under Sub-Zero Arctic Conditions

David M. McDowell, John Spielman, and Dennis Peterson

An in situ remediation system utilizing air sparge and vapour extraction technologies was installed and operated at a former gasoline retail facility in Fairbanks, Alaska. The objective of the remediation system was to treat up to 49,000 ug/L benzene in groundwater. The unique arctic conditions that needed to be overcome are extended periods of sub-zero air temperatures, deep seasonal frost extending 8 to 10 feet, a shallow groundwater table with a seasonal range of 10 to 15 feet, an average groundwater temperature of about 4 degrees Celsius, and a desire to maintain the existing operation of a retail business at a busy downtown intersection. This remediation program is being funded, in part, under the Alaska Department of Environmental Conservation (ADEC) Financial Assistance Program.

Design criteria specific to the site included a pilot test to evaluate radius of influence, air pressure and blower needs, vapour gas exhaust emissions, and system piping configuration requirements for an air sparge/vapour extraction system. The air sparge/vapour extraction system consists of eight air injection wells and four vapour extraction wells. Design considerations included optimum well placement to minimize any potential for soil vapour migration into the existing building, which was being utilized as a retail shop. The blower system is located in an equipment shed to accommodate sub-zero winter temperatures and includes the vacuum blower, air compressor, recovery drum, and appurtenances.

Remediation effectiveness has been significant in removing soil gas vapours from the vadose zone and reducing dissolved contaminants in the groundwater. Over 15 tons of petroleum hydrocarbons have been removed from subsurface soils. Benzene concentrations in groundwater have been reduced in 3 ½ years from a site wide average concentration of 22,900 ug/L to 192 ug/L.

Solvent Extraction Treatment of PCB Contaminated Soil at Sparrevohn Long Range Radar Station, Alaska

Lanny D. Weimer

This technical paper describes an on-site soil treatment project at the Sparrevohn Long-Range Radar Station (LRRS), Alaska. The project was conducted during the summer of 1996. Sparrevohn LRRS is located approximately 200 miles west of Anchorage, Alaska and is accessible only by aircraft. Polychlorinated biphenyls (PCB) contaminated soil containing between 50 and 350 milligrams/kilogram (mg/kg) was stockpiled on-site. Terra Kleen Response Group, Inc.’s (Terra Kleen’s) solvent extraction process successfully treated the stockpiled PCB contaminated soil (~290 yd³). The PCB concentrations in the treated soil were reduced below the target treatment level of 15 mg/kg. On-site solvent extraction treatment realized considerable savings (>$1,000,000) to the Government over the traditional method of hauling and off-site disposal.

Temperature Effects on Biofiltration of Off-Gases

Addanki V. Krishnayya, John G. Agar, Tai T. Wong, Barry Nevokshonoff, and Randall Warren

Several previous studies have indicated that off-gases resulting from soil and groundwater remedial operations can be treated economically with the use of biofilters to reduce air pollution. The efficiency of a biofilter depends on several factors such as retention time, uniformity of vapour flow, composition of biofilter, type of micro organisms available for biodegradation, moisture content, and temperature. This paper presents a pilot study conducted on biofilters to evaluate their performance under summer and winter temperature conditions of Calgary. The mean monthly summer and winter temperatures in Calgary vary from 17 to 23°C and from -18 to -3° respectively.

Three biofilter reactors were constructed using three steel containers each 1.22 m in diameter and 1.52 m in height. One of the three reactors was insulated on the outside with polyurethane foam insulation. Another reactor was heat traced and was also insulated on the outside. The third reactor was not provided with any thermal insulation. Humidified gasoline vapours were mixed with fresh air to provide off-gas contaminants to the biofilters. The performance of biofilters under various ambient temperatures, contaminant concentrations, and gas flow rates were evaluated. Design and practical aspects relevant to the operation of biofilters in cold temperatures were discussed.

Assessment and Remediation of Mould Bay High Arctic Weather Station: A Case Study

Edward Domijan, Chris Doupe, and Michael Nahir

The Mould Bay High Arctic Weather Station on Prince Patrick Island was initially established in 1948 as part of a joint Canadian and United States proposal to construct a series of weather stations across the Far North. Due to a variety of reasons, including the development of new automatic weather observation devices, the Mould Bay site was closed in mid 1997 for at least a two year period after which it may either be decommissioned or re-opened, if necessary. Prior to the closure, a full environmental investigation on the site was carried out in order to determine if historical uses of the site had resulted in contamination or would require action prior to temporarily mothballing the facility.

This paper will discuss the findings of the environmental investigation which led to the delineation of an area of hydrocarbon contamination adjacent to a large stream, delineation of hazardous liquids leaching from an active landfill and erosion issues affecting a closed landfill. This leads into a review of the remediation project, including consideration of the difficulties of operating in an isolated Arctic location with a minimum of available equipment and supplies. Practical examples of problems in excavating over the permafrost and within the streambed will be explored together with the successes of a project completed ahead of schedule and under projected budgets.

Bench Scale Studies for Remediation of a Hazardous Site in Helsinki, Finland

Harry Whittaker

In July 1997, the City of Helsinki Finland issued a request for proposals for a technology demonstration competition involving the clean up of a site on the Helsinki Finland which had been used for waste disposal for 50 years by a municipal incinerator and for 100 years by a ceramics factory. A consortium involving the Finnish firm IP Engineering, the Emergencies Engineering Division of Environment Canada (now the Environmental Technologies Program of SAIC Canada) and the Latvian firms Ekosaule and Baltec was formed to pursue this opportunity. That consortium was one of three selected to carry out a demonstration remediation of 500 cubic metres of contaminated soil from that site. Soils were contaminated with PCBs, heavy metals, and PAHs.

The initial phases of the consortium’s bid included a bench scale study. That study, which includes soils washing augmented by two SAIC Canada processes as well as microwave assisted solvent extraction and water based organics washing, is now well underway. Several surprises such as the level, type and distribution of organic contaminants, the speciation and leachability of the metals and the unreported high iron content of the soil have been made. This has compounded the difficulty in finalizing the process for the planned 1999 field phase. This paper reports on the methods and results of the bench scale study.