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In permafrost valleys, artesian wells often penetrate highly pressurized aquifers beneath confining subpermafrost. These wells must be quickly brought under control at installation, and heated through their operational life to prevent them from freezing in winter. However, water breakthrough of the permafrost barrier around the casing results in loss of control of the well. Seepage icing impacts to property and infrastructure can be catastrophic, and the costs to regain well control and mitigate damages high. Methods to regain control of artesian wells in permafrost are few and risky. A new method, cryogenic freezeback, was successfully used to mitigate an uncontrolled artesian well in a permafrost valley north of Fairbanks, Alaska. This paper documents the freezeback method, seepage and thermal analyses, and well abandonment and retrofit. Thermal monitoring results are presented to demonstrate the long-term effectiveness of the method.

Creative remediation schemes have been implemented with success at petroleum-contaminated sites in Alaska and Canada during the past decade. Contaminated media have been landfarmed, amended with fertilizers, augmented with microbial products, and manipulated with engineered systems. Phytoremediation developments and use of biodegradable synthetic and polymeric resins for potential use with petroleum and xenobiotic contaminants are on the horizon. Treatment of supra-permafrost water and melt-water runoff with permeable reactive barriers and partitioning bioreactors is now possible. Cost and time limitations will likely continue to drive remediation decisions in the Arctic. Environmental policy, environmental constraints, and cost will dictate what technologies are appropriate for Antarctic clean-up, although the pressure of time is less acute because land transfer and liability are not drivers. This paper discusses some recent advances in remediation engineering for use in polar regions. Conceptual models are presented, and case study treatment costs and durations are highlighted to aid environmental decision-making.

Past documented laboratory measurements have shown movement of petroleum hydrocarbons to the freezing front in contaminated freezing soils. The mechanisms that are, in part, responsible for the increased contaminant concentration at the freezing front are illustrated in this study with a mass-balance model. Results from this quantitative analysis show that this concentration increase is due to exclusion of petroleum hydrocarbon from the crystalline ice structure and from physical displacement of liquid petroleum hydrocarbon from the pore space as water freezes and expands into ice. Consequences of this process in relation to contaminant migration in freezing soils through time are discussed.

The ways by which contaminants in freezing ground disperse and interact with associated ecosystems is a new and challenging field of applied research that is crucial to effective assessment, monitoring, and remediation in cold regions. Three key issues have been identified as needing urgent research and development. The first concerns the development and application of meaningful environmental guidelines for cold regions. This usually means that contaminants in freezing ground per se need to be considered in their broadest context by also addressing associated ecosystems, such as the receiving marine environment. The second issue concerns developing best practice for bioremediation of seasonally frozen soils. Of particular concern are the risks, benefits, and costs of using so-called bioproducts, which may not offer substantial improvements over biostimulation of indigenous cold-adapted organisms. The third issue concerns the need for assessment and monitoring protocols and cost-effective analytical tools. In this respect the potential use of field portable instruments deserves careful consideration and on-site testing. Taken together, development of these issues during the coming years will be crucial if the science behind managing contaminants in freezing ground is to catch up with the knowledge that underpins the remediation industry elsewhere.

In North American cold regions, terrestrial spill-response tactics have evolved through clean-up experience with crude oil and refined petroleum products. Alaska has developed response tactics as guidelines for clean-up of petroleum-based spills. Generic application of any response tactic without regard for season, site-specific conditions, and equipment limitations can further damage an ecosystem. For example, the practice of igniting and burning petroleum product spilled onto frozen tundra without consideration of the anthropogenic effect on the surface energy balance may actually increase the vertical migration of the spilled product. Prior to application of any mitigation strategy to a release of petroleum product, the movement of the product through freezing soil needs to be better understood. Case studies are presented, and lessons learned from them are discussed.

Timely bioremediation of petroleum-contaminated soils in the Arctic is possible with innovative engineering and environmental manipulation to enhance microbial activity beyond the natural effective season. Key parameters in extending the period of beneficial microbial activity in Arctic biopiles are temperature and substrate availability. A multidisciplinary team of engineers, microbiologists and electricians has designed and installed a thermally enhanced biopile at a diesel-contaminated gravel pad in Prudhoe Bay, AK. The combination of bioventing with active warming, fertilization and power cycling is working toward timely remediation at this site. Primary components for success are the (1) thermal insulation system (TIS) design, (2) microbiological monitoring plan, and (3) power optimization. (Alternate power sources are considered for use at this and future remote bioremediation sites.) This paper discusses the TIS design and extension of the effective treatment season, fertilization and the results of a treatability study that compared simple fertilization with application of commercially available bioproducts under simulated site conditions, and adjusting power utilization to prevent permafrost thaw. Through an integrated approach to bioremediation, we are treating diesel-contaminated soils at an Arctic site.

Bioremediation of petroleum-contaminated soils in cold regions is hampered by low temperatures, frozen soils, and short summers. Extreme environmental conditions limit remedial efforts to a few technologies. Bioventing and combined air-sparging and soil vapor extraction have shown promise in subarctic regions. Expensive thermal desorption or encapsulation of organically contaminated soil is practiced in arctic Alaska and Canada, in lieu of successful bioremediation. Thermal insulation systems have recently been developed for innovative bioremediation efforts in cold regions. Commercially available insulation, electrical heating elements, and construction materials have been uniquely packaged to enhance bioremediation at two petroleum-contaminated sites in Alaska. Thermally enhanced bioventing successfully remediated hydrocarbon contamination in the vadose zone at a subarctic site within two years. Preliminary results from an oxygenated and fertilized biopile, actively warmed and covered with a thermal insulation system, show promise at an arctic site. A guide for thermal insulation system design for bioremediation application in cold regions is developed.

Dust produced from unpaved roads in rural Alaska is impacting the quality of life in many Alaskan and other villages in cold regions. Not only does dust emanating from unpaved roads cause respiratory ailments, but also impacts subsistence food storage and sources as well as safety since dust impacts visibility on village streets. Loss of fine particles also greatly impacts the quality of road surfaces creating increased maintenance costs. Replacing the fines content in unpaved road surfaces is costly owing to the lack of suitable material and equipment in many villages. The expectation for many communities is that paving their roads will solve their problems. In some cases this may be possible. In many rural environments, however, lack of suitable material or cost prohibitive sources, unsuitable foundation materials or inability to maintain the improved roads preclude pavement as an option. A suitable option for many rural villages may be dust control palliatives and institutional controls. However, there is little consensus on how to identify and measure the effectiveness, economics, and environmental impacts of dust control approaches that are compatible with the subsistence lifestyle common in remote rural communities in Alaska and other cold regions. Our objective in this ongoing study is to evaluate different dust control methods used in rural Alaska. These dust control methods include various synthetic polymer type palliatives, calcium chloride, and institutional controls. This paper presents current efforts to quantify and qualify the effectiveness of dust control measures. Of the different dust control methods, the Alaska Department of Transportation and Public Facilities (AKDOT&PF) has the most experience with calcium chloride (CaCl2). Salts such as CaCl2 (magnesium chloride is another common dust control salt used by others) control dust by adsorbing and retaining moisture in the aggregate surfacing material. These compounds are most effective at suppressing dust when the relative humidity is greater than around 30 to 40 percent (Rushing and Tingle, 2006). During morning hours when relative humidity is typically high and temperatures are low, moisture is retained in the salt treated road surface. As the temperatures rise and relative humidity drops in the afternoon, moisture losses by evaporation from the treated road surface are reduced in comparison to untreated road surfaces. Synthetic polymers comprise several different compounds that promote soil particle binding. Several different products are provided by vendors under the names EK-35, EnviroKleen, Durasoil among others. The compositions of these compounds are typically proprietary. The fraction of loftable fine particles is reduced by the aggregating action of the palliative. Anyone who has driven on unpaved roads has experienced the effect vehicle speed has on the quantity of fine particles lofted by the vehicle. Control of speeds on rural roadways when possible is one of the least expensive means to control dust.

Petroleum pollution is a significant problem in cold regions. We define cold regions as Arctic and sub-Arctic, Antarctic and sub-Antarctic, and alpine regions that exhibit permafrost or seasonally frozen ground (Filler et al. 2008b). Encountered in gravel pads, roads, and abandoned waste dumps, at remote air strips, research stations, and legacy military and mine sites, with fuel storage and dispensing facilities, and as leaked or spilled product along transport corridors (i.e., pipeline and roads), petroleum is persistent in and difficult to remove from frozen ground. Economic limitations on cleanup are associated with remoteness, access (where regulated), scant local resources, and complex logistics. Physical changes to ground brought on by sub-freezing air temperatures reduce microbial activity and alter physicochemical properties of petroleum (e.g., partial pressures — aqueous/vapor phase partitioning — and volatility). We are beginning to understand freeze–thaw effects and cryoturbation in cold contaminated soils (Biggar and Neufeld 1996; Chuvilin et al. 2001; Barnes et al. 2004; Bigger et al. 2006; Barnes and Wolfe 2008; Barnes and Biggar 2008). Cleanup decision making is usually dictated by financial circumstances, regulatory pressure, perceived risks, and liability associated with lease responsibility or transfer of land ownership (Snape et al. 2008a). Ideally, a practical remediation strategy is chosen based on a feasibility study of alternatives, with consideration for sitespecific conditions, and acceptable trade-off between cost and treatment duration. From the responsible party perspective, the cost–time relationship (Fig. 19.1) is often the single most important aspect of decision making in environmental cleanup. The regulatory perspective also considers human and ecosystem health to be of paramount importance. Irrespective of stakeholder perspective, the development of cost-effective and timely remediation strategies benefits all. Figure 19.1 illustrates cost–time relationships for developed soil treatments that have been used in cold regions.

Introduction Bioremediation in cold climates is frequently regarded with skepticism. Owners of polluted sites and regulatory agencies may doubt the effectiveness of biological degradation at near freezing temperatures. While it is true that biodegradation rates decrease with decreasing temperatures, this does not mean that bioremediation is inappropriate for cold regions. Microbial degradation of hydrocarbons occurs even around 0 °C (Chapter 4). In remote alpine, Arctic, and Antarctic locations, excavation and shipping of contaminated soil may be prohibitively expensive. Bioremediation may be the most cost-effective alternative. This chapter discusses microbial adaptation to cold temperatures as well as results of laboratory and field studies of bioremediation at low temperatures. Microorganisms can grow at temperatures ranging from subzero to more than 100 °C. Microbes are divided into four groups based on the range of temperature at which they can grow. The psychrophiles grows at temperatures below 20 °C, the mesophiles between 20 °C and 44 °C, the thermophiles between 45 °C and 70 °C, and the hyperthermophiles require growth temperatures above 70 °C to over 110 °C. The term “cold-adapted microorganisms” (CAMs) is frequently used for describing bacteria growing at or close to zero degrees Celsius. Depending on the cardinal temperatures (the minimal, the optimal, and the maximum growth temperature), CAMs can be classified as psychrophiles or psychrotrophs . Morita's (1975) definition, which holds that psychrophiles have a maximum growth temperature of less than 20 °C and an optimal growth temperature of less than 15 °C, while psychrotrophs have a maximum temperature of 40 °C and an optimal growth temperature higher than 15 °C, is widely accepted.

Introduction It is well established that microbial activity is slower at low temperatures, and that there is a corresponding decrease in biodegradation rates (Paul and Clark 1996; Walworth et al . 1999; Scow 1982; Ferguson et al . 2003b; discussed in Chapter 4). As temperatures fall to near the freezing point of water, biomineralization of hydrocarbons practically ceases. Evaporation rates are also slower at low temperature, although diesel products and more volatile fuels continue to volatilize below 0 °C. For most cold regions, soil is typically unfrozen for only 6–8 weeks, affording a short in situ or passive ex situ treatment season. Even when the ground is thawed, temperatures are generally lower than optimal for hydrocarbon-degrading bacteria (Braddock et al . 2001; Rike et al . 2003). At their simplest, thermally enhanced bioremediation schemes aim to increase microbial activity by increasing soil temperatures and extending the period when the ground is unfrozen. Modern integrated designs go much further – they typically incorporate some form of venting to promote volatilization, and deliver nutrients, oxygen, and water to hydrocarbon-degrading bacteria in attempts to optimize bioactivity. They are also designed to prevent off-site migration of contaminants and nutrient-enriched waters. Relative to other remediation options, thermally enhanced bioremediation is a low-cost treatment option (see Chapter 1, Figure 1.1). It is typically much cheaper than bulk extraction and disposal or on-site combustion/desorption treatments, perhaps by a factor of five or more, but approximately two to four times more expensive than landfarming (Chapter 9).

Introduction Oil and fuel spills are among the most extensive and environmentally damaging pollution problems in cold regions and are recognized as potential threats to human and ecosystem health. It is generally thought that spills are more damaging in cold regions, and that ecosystem recovery is slower than in warmer climates (AMAP 1998; Det Norske Veritas 2003). Slow natural attenuation rates mean that petroleum concentrations remain high for many years, and site managers are therefore often forced to select among a range of more active remediation options, each of which involves a trade-off between cost and treatment time (Figure 11). The acceptable treatment timeline is usually dictated by financial circumstance, perceived risks, regulatory pressure, or transfer of land ownership. In situations where remediation and site closure are not urgent, natural attenuation is often considered an option. However, for many cold region sites, contaminants rapidly migrate off-site (Gore et al . 1999; Snape et al . 2006a). In seasonally frozen ground, especially in wetlands, a pulse of contamination is often released with each summer thaw (AMAP 1998; Snape et al . 2002). In these circumstances natural attenuation is likely not a satisfactory option. Simply excavating contaminants and removing them for off-site treatment may not be viable either, because the costs are often prohibitive and the environmental consequences of bulk extraction can equal or exceed the damage caused by the initial spill (Filler et al . 2006; Riser-Roberts 1998).

Soil Vapor Extraction has proven to be a viable method for reducing the mass of volatile compounds from soils that have been impacted by contamination. The theory, design and use of SVE systems hav ...