Ninth International Conference on Permafrost ... - IARC Research

Adaptating and Managing Nunavik’s Transportation InfrastructureGuy DoréLaval UniversityAnick GuimondQuebec Ministry of TransportationGilles GrondinQuebec Ministry of TransportationIntroductionIn Nunavik (Quebec, Canada), an important increase inmean annual temperatures has occurred over the last 15 years.As a result, permafrost is degrading and is threatening theintegrity of roads and airfields in 13 Inuit communities. Thisstudy was initiated by the Quebec Ministry of Transportationin order to adapt transportation embankments to the newclimatic reality. The purpose of this study is to identifythe consequence of global warming on the transportationinfrastructure, to carry out a performance assessment of theNunavik runways and access roads since their construction,and to develop a management strategy in order to effectivelymaintain a safe airport and access road network in Nunavik.Problem StatementDamages observed on Nunavik’s airstrips and accessroads caused by degrading permafrost have led the QuebecMinistry of Transportation to take action. Research hasbeen undertaken to assess current and foreseeable impactson northern infrastructures, recommend adaptation strategyand propose a management plan for these transportationinfrastructure networks.Condition of Nunavik’s Airports and AccessRoadsThe study led to the identification of six unstable runwaysand two unstable access roads. Depressions along airstripedges and roadsides and water ponding in drainage ditchesare the most frequent problems observed in Nunavik. Theseproblems are mainly caused by snow accumulation on theside-slopes and by climate warming. As a result, the groundtemperature under the embankments and more specificallyunder side-slopes tends to increase, causing permafrostdegradation and loss of support if the permafrost is ice-rich.Experimentation of Protection TechniquesThree protection techniques that have the potentialfor large-scale application in Nunavik have been chosento mitigate permafrost degradation under transportationinfrastructures in Nunavik. Air convective embankment,heat drain, and reflective surfaces have been selected fortheir operational and economical feasibility. The intent isto use these techniques in cases of severe degradation onrecently paved access roads and on airstrips. The use ofprotection technique should extend the service life or reducethe maintenance requirements of Nunavik’s transportationinfrastructure. The heat drain was developed at LavalUniversity (Beaulac & Doré 2006). This technique allowsheat extraction from the embankment during winter througha highly permeable geocomposite placed in the embankmentshoulder. The air convection embankment, developed inAlaska (Goering 2003), uses convective flow in largepores of a uniform-size stone material to activate heat lossin embankments during winter. Use of reflective surfacescan reduce the n-factor and has proven to be effective inreduction of the depth of thaw penetration in permafrostregions. Reflective surfaces, based on the use of white paintapplied on pavement surfaces, have been tested in severalexperimental projects in Alaska (Reckard 1985).The solutions based on heat extraction (heat drain andconvection embankment) have been tested in a laboratory onsmall-scale embankments built in a cold room. Laboratorytesting has demonstrated the effectiveness of the heatdrain and of the air convection embankment. The resultsshowed that it is possible to lower ground temperaturesignificantly during winter when these techniques are usedin the embankment. Temperature differences reaching 7°Chave been observed between the two protection techniquesand the reference embankment. The testing program willcontinue to support thermal modeling and development ofdesign parameters for these techniques.The reflective surface has been tested at the LavalUniversity Road Experimental Site (SERUL) and the resultsof the experiment are discussed in (Stuhr-Jorgensen & Doré2007). All these techniques are also being tested in the field onthe Salluit airport access road and on the embankment of theTasiujaq airstrip. The objective of the experimental programis to assess the technical, operational, and economicalfeasibility of these techniques and to identify those havingthe best potential for large-scale application. The Salluit testsite, including six test sections, was constructed in summer2006 to determine the operational and economical feasibilityof the techniques (initial construction cost, maintenancecost, labour and materials cost, heavy equipment locationcost, and shipping cost). The three protection techniquesdescribed above have been used alone (3 sections) and bycombining the reflective surface with both heat extractiontechniques (2 sections). An additional section is used as areference to assess the relative effectiveness of the protectiontechniques.The Tasiujaq airstrip project involves the experimentationof the air convection embankment and the heat drain in theshoulder of the embankment. The project also includes a63