Introduction

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 physico-chemical 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 site-specific 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.

Dennis M. Filler

Department of Civil & Environmental Engineering, P.O. Box 755900, University of Alaska Fairbanks, Fairbanks, Alaska 99775-5900, USA e-mail: [email protected]

R. Margesin (ed.) Permafrost Soils, Soil Biology 16,

DOI: 10.1007/978-3-540-69371-0, © Springer-Verlag Berlin Heidelberg 2009

Time

Fig. 19.1 Cost-time relationships for soil treatment methods used in cold regions. Note that cost and time for a treatment are greater in polar regions (after Snape et al. 2008a). The methods are classified as physical (P), chemical (C), and biological (B)

Time

Fig. 19.1 Cost-time relationships for soil treatment methods used in cold regions. Note that cost and time for a treatment are greater in polar regions (after Snape et al. 2008a). The methods are classified as physical (P), chemical (C), and biological (B)

The methods identified in Fig. 19.1 are generally classified as physical (P), chemical (C), and biological (B). In cold regions, remediation of an equal volume of petroleum-contaminated soil is more expensive with physical than chemical treatments, and biological treatments are least expensive but require more time to meet cleanup standards. The exception is bioaugmentation, which can be as expensive as physical treatment because of the high costs of bioproducts and their repeated applications in order to achieve cleanup levels.

Groundwater treatment methods are less developed for cold region applications. Conventional pump and treat methods, air sparging, usually in conjunction with soil vapor extraction or bioventing, and use of oxygen release compounds have been used for sub-Arctic groundwater remediation. In the Arctic, in situ soil remediation has resulted in the degradation of petroleum in water. Emerging technologies that offer potential use in polar regions include permeable reactive barriers, two-phase partitioning bioreactors, and controlled release nutrients (i.e., bioremediation). Natural attenuation as a water treatment method is little understood, and is rarely considered for polar applications. Consequently, there is insufficient comparative information to infer cost-time trends for cold-climate groundwater treatment methods. A general distinction between the regions is that a subsurface water table is often encountered in sub-polar regions, that is more amenable to conventional treatment than is runoff or suprapermafrost water encountered above permafrost of contaminated sites in polar regions. For this reason, some methods identified in Tables 19.1 and 19.2 that are suitable for treating contaminated groundwater in the

Table 19.1 Ex situ soil remediation techniques with limitations to consider for application in cold regions

Technique

Description

Limitations

Ex situ soil treatment

Physical processes Dig & haul

Incineration

Thermal desorption

Excavation and transportation of contaminated soil to off-sight location for treatment

High-temperature thermal destruction of organic contaminants in soil

Low-temperature (600-900°C) thermal destruction of oxidizable hydrocarbons with low boiling points

Incorporation & encapsulation

Excavation and use of contaminated soil at off-sight road or airport location. Contaminated soil is incorporated or encapsulated in roadbed, runway, or tarmac

Chemical processes

Soil washing Reactor-based soil treatment whereby organic contaminants are desorbed from soil and treated via multi-stage processing.3 Mobile washers use hot water, flotation and/or flocculation, and surfactants to remove contaminants

Chemical treatments Contaminated soil is excavated and constructed as a lined heap or parceled into a liquid/solid contactor, for infusion with an oxidizer (e.g., peroxide, hydrogen peroxide, or ozone) or submersion in an alkaline/ surfactant solution to liberate organic contaminants

Warm season application; practical where roads and infrastructure exist; requires additional treatment; used in the Arctic and Antarctica; expensive

— high transportation cost Practical Apr-Oct in the Arctic; few fixed-based incinerators available; treated soil is sterile; expensive

— high energy and O&M costs; cost-prohibitive for Antarctic use

Practical May-Sept. in the Arctic; mobile and fixed-base units available; treated soil is sterile; expensive — high energy and O&M costs; cost-prohibitive for Antarctic use

Selective use during Arctic warm season where roads and airports exist; requires special permitting and work plans, long-term monitoring, and may incur long-term liability; can be expensive — high transportation cost; not yet considered for use in Antarctica

Practical in on-site mobile units

May-Sept in the Arctic; separated contaminant residual requires additional treatment as potential hazardous waste; requires on-site power; cost-prohibitive and environmental risks high for Antarctic use

Practical in on-site mobile units

May-Sept in the Arctic; separated contaminant residual requires additional treatment and may be considered a hazardous waste; some contactors require on-site power; may have potential for Antarctic use

(continued)

Technique

Description

Limitations

Biological processes

Bioaugmentation

Composting

Landfarming

Thermally enhanced bioremediation

Use of allochthonous microorganisms (naturally occurring, designer, or genetically engineered) to achieve bioremediation

Prepared-bed treatment using a bulking agent, aeration, and heat generated from biological decomposition of organic contaminants under controlled (moisture, nutrients, and pH) conditions Prepared-bed treatment using periodic tilling to degrade organic contaminants in soil.b Nutrient-enhanced landfarming induced volatilization and biodegradation to reduce hydrocarbon concentrations in soilc Biopiles engineered with mechanical systems (e.g., bioventing, nutrient infusion, and soil heating) and optimized to achieve bioremediation

Practical for enclosed soil treatment under controlled and optimized conditions; unregulated or semi-regulated for Arctic warm season use; comparable but much more expensive than commercially available fertilizers; science of consequence not yet established; prohibited in Antarctica

Practical yet not well-developed for on-site treatment from May to Sept in the Arctic, and Dec to Feb in coastal Antarctica; beds must be enclosed and insulated for practical use in polar regions

Practical for on-site treatment from May to Sept in the Arctic, and Dec to Feb in coastal Antarctica; used in Arctic and sub-Arctic regions; highly dependent on environmental conditions

Practical for on-site treatment of constructed biopiles from April to Nov in the sub-Arctic and Arctic; requires energy for mechanical systems; remote applications require alternative energy (e.g., solar, diesel-electric, fuel cell, hybrid) source; treatment regime can be manipulated independent of climatic conditions; not yet trialed in Antarctica

O&M operation and maintenance aLyman et al. (1990) bVidali (2001) cWalworth et al. (200S)

sub-Arctic with vertical wells are not amenable to treatment of near-surface waters in the Arctic and Antarctica.

In this chapter, we discuss the feasibility and limitations of practical remediation of petroleum hydrocarbons in cold regions. We rely on lessons learned from cold-climate experiences in both hemispheres, and latest developments in contaminant

Table 19.2 In situ soil remediation techniques with limitations to consider for application in cold regions (see Table 19.1)

Technique

Description

Limitations

In situ soil treatment

Chemical processes

Soil washing See Table 19.1 description

Biological processes

Bioaugmentation See Table 19.1 description

Phytoremediation

Soil vapor extraction with air sparging (SVE/AS)

The destruction, removal, or immobilization of soil contaminants brought about by plants and associated organisms

Combination of vacuum enhanced recovery of volatilized hydrocarbons from the vadose zone, and use of air-injection wells to aerate and liberate hydrocarbons from groundwater

The process of supplying (warmed) air to soil to stimulate aerobic biodegradation of contaminantsa

Thermally enhanced

Bioremediation See Table 19.1 description

Bioventing

Not recommended for in situ use in cold regions without controlled containment and perimeter monitoring. Perceived to have negative impacts on soil ecology and permafrost. Cost-prohibitive for Antarctic use

Not recommended until science of consequence is established. Unregulated or semi-regulated for summer Arctic use. Comparable to but much more expensive than commercially available fertilizers. Highly susceptible to climatic conditions and temperature. Prohibited in Antarctica

Potentially useful but not yet developed for use in cold regions. Highly susceptible to climatic conditions and temperature. Not practical for use in Antarctica

Amenable to granular soils (not fine silts and clays); used extensively from May to Oct in the sub-Arctic; not practical for use in the Arctic or coastal Antarctica with shallow contaminant zones; requires on-site energy; offers low O&M and monitoring costs; treatment durations highly variable and difficult to predict. Could be used with biopiles as ex situ engineered bioremediation in polar regions

Amenable to granular soils (not fine silts and clays); used from May to Oct in the subArctic; used with thermally enhanced biore-mediation in the Arctic; not practical for use in the Arctic or coastal Antarctica with shallow contaminant zones; requires on-site energy; offers low O&M and monitoring costs; treatment durations somewhat variable but more predictable than SVE/AS

Biopiles can be constructed as in situ/ex situ structures; annual treatment from April to Nov in the sub-Arctic and Arctic; same energy requirements/limitations as with ex situ treatment; treatment regime can be manipulated independent of climatic conditions; maintaining permafrost integrity essential; not yet trialed in Antarctica

O&M, operation and maintenance aNorris et al. (1994)

transport in freezing and frozen ground (see Chap. 18). Groundwater treatment is discussed as a consequence of soil treatment, with consideration for the relatively few documented field trials, and for emerging technologies.

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