A Homeowner’s Guide to in the

Keep Your House on Solid Ground Publication, contents and images copyright, 2015

Environment Division Department of Environment and Natural Resources Government of the Northwest Territories PO Box 1320, 7th Floor, Scotia Center, 5102 Franklin Ave, , NT, X1A 2L9, (867) 873-7854 www.nwtclimatechange.ca

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Yellowknife, NWT A Homeowner’s Guide to Permafrost in the Northwest Territories Acknowledgements The Government of the Northwest Territories Should Department of Environment and Natural Resources would like to acknowledge the contributions of colleagues within other departments of the GNWT, the Geological I Be Survey of Canada and the Government of Environment Department; all of whom contributed time and resources to Concerned the creation of this guide. About Permafrost is common and exists under many houses in the NWT Permafrost?

This Guide is not a legal document nor is The Guide is intended to provide it intended to be a complete manual on homeowners with general information dealing with problems caused by permafrost on permafrost, the damage permafrost to your home. The Government of the thaw can cause to a house and areas Northwest Territories does not assume any where maintenance or risk prevention is responsibility or liability with respect to advisable. It is not meant as a replacement any damage or loss arising from the use or for site-specific geotechnical investigations interpretation of this Guide. It is provided by by engineering and / or geoscience the Department of Environment and Natural professionals. Resources as a courtesy only.

With federal support through Natural Resources Canada’s Regional Adaptation Collaborative Program. 1 3 7 12 21

Permafrost Permafrost and My House Is My House on Ice-Rich Permafrost? Living on Permafrost Foundation Checklist Should I Be Concerned About Permafrost?

5 Permafrost

Permafrost is ground that is frozen for two or more years. That ground can be rock, gravel, sand, clay, silt or a mix of these. Ground that contains a great deal of frozen water, or ice causes the most problems for engineers and homeowners. When ice-rich permafrost thaws, the ice melts to water, creating spaces in the soil that lead to ground settlement and building problems.

This Guide contains information on permafrost as it is used in designing a house. It can also help you determine if your home is built on permafrost, the risks related to thawing and tips on how to properly maintain your house Ice-rich permafrost from a core sample photo by Mike Palmer and foundation to reduce permafrost thaw. There is also information on other northern Northern engineers and architects have long foundation issues such as rotting piles and developed innovative techniques to deal with the shifting of heating oil tanks. challenges of building on permafrost. However, climate change is causing rapid changes to Keeping your house and foundation in good the permafrost that was once thought would repair is one way to avoid the risks caused by be around for generations. Homeowners in the the thawing of permafrost. Every community NWT are starting to realize that their houses and every house faces different permafrost rely on potentially unstable permafrost that may related challenges. Determining what is lie under their home. Cracking walls and doors happening to the ground your house sits on is that won’t close are early indications of bigger the best way to figure out your level of risk and problems that may lie ahead. how to deal with it.

1 Air temperatures and permafrost distribution by latitude (°N) in the NWT Latitude (°N) N Credit: Modified from Wolfe,S 1998

Tuktoyaktuk Yellowknife -10.2°C -8.8°C -5.5°C -4.6°C -2.9°C 70° Treeline 65° 60° 0 Permafrost Great 200 Slave Mackenzie 400 River

Depth (m) Depth 600 800 Continuous Extensive Sporadic permafrost discontinuous discontinuous permafrost permafrost N Latitude (°N) S

Tuktoyaktuk Inuvik Norman Wells Yellowknife Hay River Permafrost-10.2°C is found throughout the-8.8°C Northwest -5.5°CIce-rich permafrost,-4.6°C the type that -2.9°Ccan be most Territories but tends to be more common harmful to houses when it thaws, is generally found further .70° PermafrostTreeline also tends to be in river65° valleys, low-lying peaty ground and soil60° thickerBeaufort and colder in the northern . For pockets in bedrock areas. Ice-rich areas are found example,Sea the0 around Tuktoyaktuk has in isolated patches throughout the Northwest cold, continuous permafrost,Permafrost often hundreds Territories but are most commonGreat in the Northern 200 Slave of metres thick. Hay River has sporadicMackenzie Islands, Beaufort Delta area and along the patches400 of relatively warm and shallow Mackenzie Valley. Mean annualLake air temperatures permafrost. Areas between these communities River are often a good indicator of the presence have discontinuous permafrost which can vary of permafrost. The average air temperatures Depth (m) Depth 600 from patchy to widespread. from 1971-2000 are shown for some NWT 800 communities in the figure above. Continuous Extensive Sporadic permafrost discontinuous discontinuous permafrost permafrost 2 How can Permafrost

 Frost-Heave Many houses in the NWT use the strength of The upward movement of the ground surface permafrost to keep their foundation solid. caused by the formation of ice in the soil. When permafrost thaws, the house may no longer have a solid base to hold it up. This  Thaw Settlement can lead to uneven floors, cracks in walls The downward movement of the ground due to and, eventually, serious structural problems. ice melting in the soil.

Many factors affect permafrost stability.  Piles It is important homeowners understand how Wooden or steel building supports drilled into their actions affect permafrost. The good the permafrost are called piles. They are less news is you can reduce permafrost thaw susceptible to settling, but are subject to and, even re-grow permafrost.  creeping (moving down) or  frost-jacking (moving up) as permafrost warms. Surface Foundation  Permafrost These adjustable foundations that sit on a gravel pad or concrete footings are more Ground that remains frozen for at least affected by thaw settlement and frost-heave two years. than piles. Examples include pad and wedge, space frames or screw jacks (see page 11).  Active Layer The top layer of ground that is subject to  Organic Layer annual thawing and freezing. When the active The top layer of dark soil or peat. A thick layer gets deeper, it can thaw the ice-rich organic layer insulates the permafrost in the permafrost below and cause thaw settlement. summer. Disturbing the organic layer usually results in rapid permafrost thaw.  Ice-Rich Permafrost Permafrost containing excess ice. Ice-rich  Gravel Pad permafrost can form thick layers of ice The gravel pad is designed to insulate the (lenses) in clay or silty soils, which can melt permafrost and allow water to move through and cause thaw settlement. the pad and away from the house.

3 Impact My House

10 9

8 7 3 4 Permafrost In the Summer

It is natural for the top layer of soil to in causing permafrost thaw, as groundwater thaw in the summer. When this active layer transfers heat more easily than dry ground. gets deeper every year, it is considered Wind evaporates moisture under your house, permafrost thaw. which helps keep the ground dry and prevents permafrost thaw. Four main factors affect how much permafrost thaws in the summer under your house: temperature, sun, water and wind. The Tip: Think of the space under your house. warmer it gets under your house, the more Can you reduce the negative factors of permafrost will thaw. The sun also warms water, sun and temperature while helping the ground and thaws permafrost, but your the positive factor of wind? foundation is usually shaded from the sun’s full effects. Water may be the greatest factor

temperature sun water wind

5 Permafrost In the Summer In the Winter

Winter is the season when permafrost keeps the cold from reaching into the ground rebuilds. The cold temperatures and low and prevents permafrost from re-growing. Wind snowfall in NWT winters provide good moves the snow around and deposits it in conditions for refreezing the ground that protected areas while exposing windswept areas. thawed the previous summer.

There are three main factors that affect how Tip: Winter winds should be allowed to much the permafrost will rebuild under your blow under your house to remove snow house in the winter. They are temperature, build-up. This exposes the ground to snow and wind. Cold temperatures must very cold temperatures that re-build the reach deep into the ground to recharge the permafrost every year. permafrost b ut, snow acts like a blanket. It

temperature snow wind

Skirting

6 Is My House on Ice-Rich Permafrost?

Inuvialuit communities typically have This is a good question that may not very cold (-5°C to -8°C) permafrost. While this have an easy answer. The following clues permafrost is in less danger of thawing, it does and information on the next four pages contain a lot of ice, which could cause major may help! problems for homeowners. Gwich’in communities are the most at risk of permafrost thaw with warm (-1°C to Do I live in a community that is sensitive to -3°C) ice-rich permafrost. changes in permafrost thaw? pg 8 temperature or surface conditions can cause Some tree and plant species can be indicators the ice to melt causing thaw settlement. of permafrost. Are these trees and plants communities have warm permafrost around my house? pg 9 (0°C to -2°C) and enough ice-rich permafrost to What type of soil do I have around my cause concern. Conditions can vary within the house? pg 9 .

Does my house have cracks in the drywall, Dehcho communities have discontinuous sloping floors, doors that do not close properly, permafrost, which is very warm (0°C to -0.5°C). or an uneven roofline? pg 9 It is not always ice-rich but isolated ice lenses do pose a risk to some homeowners. Ask around? The local housing corporation, town foreman or a neighbour will likely North Slave communities often sit over have information on permafrost in my bedrock. There are isolated patches of ice-rich neighbourhood. pg 9 permafrost, which are very thaw sensitive (0°C to -1°C). These lenses are often found in Permafrost is often not that deep. Dig a hole to flat areas, which are preferred building sites. find out if permafrost is present. pg 9 communities are least at risk. Is my house built on a gravel pad with a space South Slave There is sporadic permafrost and often sandy frame, screw jacks, pad and wedge, or on soils.The few ice-rich areas are very warm wooden or steel piles? If it is, there is a good (0°C to -0.5°C) and prone to thawing. chance it is built on permafrost (although not necessarily ice-rich). pg 11

7 Community Sensitivity to Permafrost

This map highlights the risks of permafrost thaw, caused by climate change in each NWT community. Communities most at risk are generally located in the Beaufort Delta, where ice- rich permafrost is common. Southern, road accessed communities are typically at less risk. Communities in the extensive discontinuous region (light blue area), generally have a more moderate risk to infrastructure of permafrost thaw.

Community sensitivity to permafrost derived from EBA Engineering Hoeve (2005) Permafrost distribution derived from Heginbottom et al. (1995) Canada Centre for Centre canadien Seasonal Surface Displacement Derived from InSAR, Yellowknife and Surrounding Area, Remote Sensing de télédétection Northwest Territories

114°28'0"W 114°27'0"W 114°26'0"W 114°25'0"W 114°24'0"W 114°23'0"W 114°22'0"W 114°21'0"W 114°20'0"W Seasonal surface displacement was derived for Yellowknife and the surrounding area using satellite Interferometric Synthetic Aperture Radar (InSAR) data from the summer of 2010. RADARSAT-2 Ultra-fine scenes acquired on May 21, July 8, August 1, August 25 and September 18 were interferometrically stacked and the total amount of summer vertical displacement was calculated according to the methodology outlined in Short et al. (2011, Remote Sensing of Environment, doi:10.1016/j.rse.2011.08.012). Each displacement measurement is representative of a ground surface area of approximately 5 m x 4 m. InSAR results in this map have only been qualitatively evaluated and therefore Investigaaret presentede in termsY ofo the relativeu amountr ofH displacemento andu not absolutese and values. Stable ground represents locations where no vertical change was Long calculated or where displacement was within the expected range of error (+/-1 Highway 3 cm). Low and moderate downward displacement represents surface decrease Lake 62°28'30"N on the order of -1 to -3 cm and -3 to -6 cm, respectively. Upward displacement represents a surface increase of up to 6 cm. At some locations, a loss of Sikyea Tili interferometric coherence occurred as a result of significant changes in surface characteristics and no calculations were made.

the Area Around It 62°28'30"N Highway 3 The depicted surface displacement may be a product of natural or Morrison Dr human-induced processes. Downward surface displacement may result from seasonal subsidence caused by thawing of the active layer (seasonally-frozen ground) or permafrost (perennially-frozen ground) or soil compaction. Upward Yello surface displacements may result fromVegetation ground surface heave provides or vegetation a good clue Air growth. At present, no explicit displacement process is inferred from the InSAR data, though probable causes of displacementabout the may existence be derived of from permafrost field in a inspections. Future map versions may include a quantitative assessment of the Jackfish calculations and the net surface displacementlocation. determined Look for over an consecutive undisturbed area near years. Lake

your house that looks similar to your lot. 62°28'0"N

Date Sources and Acknowledgements:Stunted black spruce, willows, tea

Old Airport Rd Road network and existing buildings courtesyand of peaty the City orof Yellowknife; spongy transportation ground often indicate

right-of-way and former building footprint courtesy of the NWT Department of Municipal and 62°28'0"N Community Affairs (MACA); trail networks permafrost.courtesy of the City Firm,of Yellowknife well-drained and MACA); soil and large National Topographic Database water bodiestrees at 1: 50 000such scale asfrom whiteGeoGratis; spruce mapping and and pine often St 48 data support by Colin Avey, GNWT, Environment and Natural Resources Division. Franklin Ave indicate a lack of permafrost. Niven Black spruce and willows can be indicators of permafrost Lake

43 St Disclaimer Soil Type can also be used to determine the Her Majesty the Queen in right of Canada as represented by the Minister of Natural Resources, the Government of the Northwest Territories as represented by Environment and Natural Resources and Municipal and Community Affairs, and the Citylocation of Yellowknife, of do ice-richnot warrant or permafrost.guarantee the Greyish fine- accuracy or completeness of the information (“Data”) on this map and do not assume any 62°27'30"N responsibility or liability with respect to any damagegrained or loss arising clay from or the riveruse or interpretation soil is moreof likely to contain the Data. ice-rich permafrost. Gravel, sand, and coarse Frame The Data on this map are intended to convey regional trends and should be used as a guide only. Lake Ave Draw School The Data should not be used for design or construction at any specific location, nor are the Data to 47 St be used as a replacement for the types of site-specificsoils geotechnical allow investigations.water to drain through62°27'30"N and, therefore, 48 St Magrum Cres are less likely to contain ice-rich permafrost. 49 St 49 Ave 50 Ave 50 St Yellowknife 51 St LEGENDHouse Shifting is common in the NWT Bay 53 St Borden Dr and is not always caused by permafrost. If you Rivett Cres Herriman Rd Trails Franklin Ave Relative surface displacement have cracks in the drywall, doors that don’t 52 Ave Roads 62°27'0"N Moderate downward displacement close,(-3 to -6 cm) sloping floors and an uneven roofline, Ask around for advice Transportation right-of-way Low downward displacement (-1 to -3your cm) house couldExisting buildingsbe built on permafrost.

Stable (+/- 1 cm) Former building footprint 51a Ave 62°27'0"N Range Upward displacement (1 to 6 cm) Ask your Waterneighbours, the community Lake Old Airport Rd Loss of InSAR coherence foreman, an Noequipment data operator or the town Forest Dr son Dr N lay in Senior Administrative Officer (SAO). Many F Franklin Ave

people will know about permafrost in your Con Rd The map is available from:neighborhood. The Geological Survey of Canada Bookstore

(http://gsc.nrcan.gc.ca/bookstore_e.php). 62°26'30"N It can also be downloaded free of charge from Taylor Rd to see if you hit permafrost. Braathen Ave d GeoPub (http://geopub.nrcan.gc.ca/).Dig a hole R e k a Finlayson Dr N L e The best time to perform this test is in late g

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R summer, when the active layer is62°26'30"N deepest. You’ll know you hit permafrost when you can Yellowknife OPEN FILE Open files are products study area dig no deeper. thatDig have not ingone a undisturbed area of DOSSIER PUBLIC through the GSC formal publication process. your property7030 that appears similar to where your Les dossiers publics sont GEOLOGICAL SURVEY OF CANADA des produits qui n’ont houseCOMMISSION sits.GÉOLOGIQUE DU CANADAPaypas attention été soumis au to the soil type as you Rd processus officiel de Deh Cho Blvd dig. 2011 publication de la CGC. 62°26'0"N ©Her Majesty the Queen in Right of Canada 2011 Permafrost is often not very deep Pud Lake

62°26'0"N Kam Kilometres Enterprise Dr Recommended citation: Lake 0 0.5 1 Short, N., Stevens, C.W., and Wolfe, S.A. 2011. Seasonal Universal Transverse Mercator Projection Surface Displacement Derived from InSAR, American Datum 1983 9 and Surrounding Area, Northwest Territories; Geological Map scale 1: 15 000 Survey of Canada, Open File 7030, 1 CD-ROM. doi:10.4095/289578 Kam Lake Rd 114°28'0"W 114°27'0"W 114°26'0"W 114°25'0"W 114°24'0"W 114°23'0"W 114°22'0"W 114°21'0"W Canada Centre for Centre canadien Seasonal Surface Displacement Derived from InSAR, Yellowknife and Surrounding Area, Remote Sensing de télédétection Northwest Territories

114°28'0"W 114°27'0"W 114°26'0"W 114°25'0"W 114°24'0"W 114°23'0"W 114°22'0"W 114°21'0"W 114°20'0"W Seasonal surface displacement was derived for Yellowknife and the surrounding area using satellite Interferometric Synthetic Aperture Radar (InSAR) data from the summer of 2010. RADARSAT-2 Ultra-fine scenes acquired on May 21, July 8, August 1, August 25 and September 18 were interferometrically stacked and the total amount of summer vertical displacement was calculated according to the methodology outlined in Short et al. (2011, Remote Sensing of Environment, doi:10.1016/j.rse.2011.08.012). Each displacement measurement is representative of a ground surface area of approximately 5 m x 4 m. InSAR results in this map have only been qualitatively evaluated and therefore are presented in terms of the relative amount of displacement and not absolute Ingraham Trail values. Stable ground represents locations where no vertical change was Long calculated or where displacement was within the expected range of error (+/-1 Highway 3 cm). Low and moderate downward displacement represents surface decrease Lake 62°28'30"N on the order of -1 to -3 cm and -3 to -6 cm, respectively. Upward displacement represents a surface increase of up to 6 cm. At some locations, a loss of Sikyea Tili interferometric coherence occurred as a result of significant changes in surface characteristics and no calculations were made.

62°28'30"N Highway 3

The depicted surface displacement may be a product of natural or Morrison Dr human-induced processes. Downward surface displacement may result from seasonal subsidence caused by thawing of the active layer (seasonally-frozen Canada Centre for Centre canadien Seasonal Surface Displacementground) or permafrost (perennially-frozenDerived ground) from or soil compaction. InSAR, Upward Yellowknife and SurroundingYellowknife Area, Remote Sensing de télédétection surface displacements may result from ground surface heave or vegetation Airport growth. At present, no explicit displacement process is inferred from the InSAR data, though probable causes of displacement may be derived from field inspections. Future map versionsNorthwest may include a quantitative Territories assessment of the Jackfish calculations and the net surface displacement determined over consecutive years. Lake

114°28'0"W 114°27'0"W 114°26'0"W 114°25'0"W 114°24'0"W 114°23'0"W 114°22'0"W 114°21'0"W 114°20'0"W 62°28'0"N Seasonal surface displacement was derived for Yellowknife and the surrounding area using satellite Interferometric Synthetic Aperture Radar (InSAR) data from Date Sources and Acknowledgements: the summer of 2010. RADARSAT-2 Ultra-fine scenes acquired on May 21, July 8, Old Airport Rd August 1, August 25 and September 18 were interferometrically stacked and the Road network and existing buildings courtesy of the City of Yellowknife; transportation total amount of summer vertical displacement was calculated according to the right-of-way and former building footprint courtesy of the NWT Department of Municipal and 62°28'0"N methodology outlined in Short et al. (2011, Remote Sensing of Environment, Community Affairs (MACA); trail networks courtesy of the City of Yellowknife and MACA); doi:10.1016/j.rse.2011.08.012). Each displacement measurement is National Topographic Database water bodies at 1: 50 000 scale from GeoGratis; mapping and St 48 representative of a ground surface area of approximately 5 m x 4 m. data support by Colin Avey, GNWT, Environment and Natural Resources Division. Niven Franklin Ave InSAR results in this map have only been qualitatively evaluated and therefore are presented in terms of the relative amount of displacement and not absolute Ingraham Trail Lake Long 43 St values. Stable ground represents locations where no vertical change was Disclaimer calculated or where displacement was within the expected range of error (+/-1 Highway 3 Lake 62°28'30"N cm). Low and moderate downward displacement represents surface decrease Her Majesty the Queen in right of Canada as represented by the Minister of Natural Resources, the on the order of -1 to -3 cm and -3 to -6 cm, respectively. Upward displacement Government of the Northwest Territories as represented by Environment and Natural Resources and Municipal and Community Affairs, and the City of Yellowknife, do not warrant or guarantee the Sikyea Tili represents a surface increase of up to 6 cm. At some locations, a loss of 62°27'30"N Seasonalaccuracy or completeness of the information (“Data”) on this map and doGround not assume any Shifting interferometric coherence occurred as a result of significant changes in surface responsibility or liability with respect to any damage or loss arising from the use or interpretation of characteristics and no calculations were made. the Data.

62°28'30"N Highway 3 Frame The depicted surface displacement may be a product of natural or The Data on this map are intended to convey regional trends and should be used as a guide only. Morrison Dr Lake Ave Draw School The Data should not be used for design or construction at any specific location, nor are the Data to 47 St

human-induced processes. Downward surface displacement may result from 62°27'30"N be used as a replacement for the types of site-specific geotechnical investigations. seasonal subsidence caused by thawing of the active layer (seasonally-frozen 48 St Magrum Cres ground) or permafrost (perennially-frozen ground) or soil compaction. Upward 49 St 49 Ave 50 Ave surface displacements may result from ground surface heave or vegetation 50 St Yellowknife growth. At present, no explicit displacement process is inferred from the InSAR 51 St data, though probable causes of displacement may be derived from field inspections. Future map versions may include a quantitative assessment of the LEGEND Jackfish Bay 53 St calculations and the net surface displacement determined over consecutive Borden Dr years. Lake Rivett Cres Herriman Rd

Trails 62°28'0"N Franklin Ave Relative surface displacement 52 Ave Roads Date Sources and Acknowledgements: 62°27'0"N

Moderate downward displacementOld Airport Rd (-3 to -6 cm) Transportation right-of-way Road network and existing buildings courtesy of the City of Yellowknife; transportation Low downward displacement (-1 to -3 cm) right-of-way and former building footprint courtesy of the NWT Department of Municipal and 62°28'0"N Existing buildings Community Affairs (MACA); trail networks courtesy of the City of Yellowknife and MACA);

Stable (+/- 1 cm) Former building footprint St 48 51a Ave National Topographic Database water bodies at 1: 50 000 scale from GeoGratis; mapping and 62°27'0"N Range data support by Colin Avey, GNWT, Environment and Natural Resources Division. Upward displacement (1 to 6 cm) Water Franklin Ave Lake Niven Old Airport Rd Forest Dr Loss of InSAR coherence No data Lake son Dr N lay 43 St in Disclaimer F Franklin Ave This map can be downloaded free of charge at geoscan.ess.nrcan.gc.ca Her Majesty the Queen in right of Canada as represented by the Minister of Natural Resources, the Con Rd Government of the Northwest Territories as represented by Environment and Natural Resources and Municipal and Community Affairs, and the City of Yellowknife, do not warrant or guarantee the The map is available from: accuracy or completeness of the information (“Data”) on this map and do not assume any 62°27'30"N responsibility or liability with respect to any damage or loss arising from the use or interpretation of The Geological Survey of Canada Bookstore

the Data. (http://gsc.nrcan.gc.ca/bookstore_e.php). 62°26'30"N It can also be downloaded free of charge from Frame Taylor Rd

School Draw Ave Draw School Braathen Ave d The Data on this map are intended to convey regional trends and should be used as a guide only. GeoPub (http://geopub.nrcan.gc.ca/). R e Lake k The Data should not be used for design or construction at any specific location, nor are the Data to 47 St a L 62°27'30"N Finlayson Dr N be used as a replacement for the types of site-specific geotechnical investigations. e 48 St g Magrum Cres n a

49 St R 62°26'30"N 49 Ave 50 Ave 50 St Yellowknife 51 St

Yellowknife OPEN FILE Open files are products Bay LEGEND study area that have not gone 53 St Borden Dr DOSSIER PUBLIC through the GSC formal publication process. Rivett Cres Herriman Rd 7030 Franklin Ave Trails Les dossiers publics sont 52 Ave Relative surface displacement GEOLOGICAL SURVEY OF CANADA des produits qui n’ont Roads COMMISSION GÉOLOGIQUE DU CANADA pas été soumis au Kam Lake Rd processus officiel de Deh Cho Blvd 62°27'0"N 2011 publication de la CGC. Moderate downward displacement (-3 to -6 cm) Transportation right-of-way 62°26'0"N Low downward displacement (-1 to -3 cm) Existing buildings ©Her Majesty the Queen in Right of Canada 2011

Stable (+/- 1 cm) Former building footprint Pud 51a Ave 62°27'0"N Range Upward displacement (1 to 6 cm) Water Lake Lake Old Airport Rd 62°26'0"N Forest Dr Kam Kilometres Loss of InSAR coherence No data Enterprise Dr Recommended citation: 0 0.5 1 son Dr N Lake lay in F Short, N., Stevens, C.W., and Wolfe, S.A. 2011. Seasonal Franklin Ave Universal Transverse Mercator Projection Surface Displacement Derived from InSAR, Yellowknife North American Datum 1983 and Surrounding Area, Northwest Territories; Geological Con Rd Map scale 1: 15 000 The map is available from: Survey of Canada, Open File 7030, 1 CD-ROM. doi:10.4095/289578 Kam Lake Rd The Geological Survey of Canada Bookstore 114°28'0"W 114°27'0"W 114°26'0"W 114°25'0"W 114°24'0"W 114°23'0"W 114°22'0"W 114°21'0"W

(http://gsc.nrcan.gc.ca/bookstore_e.php). 62°26'30"N It can also be downloaded free of charge from Taylor Rd Braathen Ave d GeoPub (http://geopub.nrcan.gc.ca/). R e k a L Finlayson Dr N e g

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R 62°26'30"N This InSAR satellite map of Yellowknife shows changes in the elevation of the ground surface over the summer of 2010. Yellowknife OPEN FILE Open files are products study area that have not gone Downward movement (yellow and orange) is most likely a DOSSIER PUBLIC through the GSC formal publication process. 7030 result of thaw settlement and upward movement (purple) is Les dossiers publics sont GEOLOGICAL SURVEY OF CANADA des produits qui n’ont COMMISSION GÉOLOGIQUE DU CANADA pas été soumis au Kam Lake Rd typically caused by frost heave. The GNWT in partnership processus officiel de Deh Cho Blvd 2011 publication de la CGC. with NRCan is working to develop InSAR maps for all NWT ©Her Majesty the Queen in Right of Canada 2011 62°26'0"N communities to helpPud with land-use planning. Lake Short, N., et al. 2011 62°26'0"N Kam Kilometres Enterprise Dr Recommended citation: Lake 0 0.5 1 Short, N., Stevens, C.W., and Wolfe, S.A. 2011. Seasonal Universal Transverse Mercator Projection Surface Displacement Derived from InSAR, Yellowknife North American Datum 1983 and Surrounding Area, Northwest Territories; Geological Map scale 1: 15 000 Survey of Canada, Open File 7030, 1 CD-ROM. doi:10.4095/289578 Kam Lake Rd 114°28'0"W 114°27'0"W 114°26'0"W 114°25'0"W 114°24'0"W 114°23'0"W 114°22'0"W 114°21'0"W Foundation Types

Steel Piles Screw Jacks Drilled six to twelve metres into This system uses adjustable jacks the ground and permafrost. With to keep the house level and are a 50-year life expectancy, they typically built on a gravel pad. should outlast your house. However, Annual maintenance is required. permafrost thaw can cause frost jacking and creep. Space Frames Space frames are a relatively Wooden Piles new technology to deal with Wooden piles are drilled into unstable permafrost. The web of permafrost and have a shorter metal tubes provide strength and lifespan than metal. Permafrost adjustability. thaw may cause shifting. Improperly treated piles are prone to rotting. A combination of moisture and In-Ground Basement Concrete, or wooden basements, air eat away at the top of piles or houses with crawl spaces should and leave a weak shell with little not have been built on ice-rich strength. permafrost. If you have a below- ground foundation, frost-heave is Pad & Wedge your biggest worry. Try to keep Stacks of pressure treated lumber water away from your foundation. hold the foundation of the house off the ground. The blocks should be on a gravel pad and require periodic maintenance to keep the house level.

11 Foundation Types Living on Permafrost

Your house may not be at risk. A number of factors affect how your house will deal with the potential of permafrost thaw. If you have not had any problems with your foundation settling, you may not have to worry about permafrost thaw.

Permafrost does not change rapidly, but it can significantly deteriorate under a house over a number of years due to poor practices and maintenance. Understanding how permafrost is affected by the weather, your house and some of the things you do is the first step in reducing your risk of permafrost thaw.

Many properly-designed, built and maintained houses will outlast their owners and show no A structure with foundation issues due to permafrost wear or tear from permafrost thaw. If your foundation is not very solid, you may want to pay more attention to why it is shifting. The following pages will help you understand how skirting, water, snow, wind and other factors affect the permafrost under your house and what you can do about it.

Permafrost degradation affecting foundations

12 Water

Moisture or water under your house can promote permafrost thaw. Wet soil transfers heat to permafrost more easily than dry soil and can accelerate permafrost melt. Water in the ground can also cause frost heave and thaw settlement as the water freezes in fall and thaws in the summer.

Houses should be designed to move water away from the foundation. Gravel pads allow water Ice and water under your house may lead to permafrost degradation to infiltrate and drain away from the house. If you have water pooling under your house you should take measures to reduce this.

Tip

Moisture, ice or standing water under a house built on permafrost can cause problems. Follow these tips to keep moisture and water away from Gravel pad should be domed to shed water your house:

‹ Extend the drainpipe from your eavestroughs away from the house. Ask yourself these questions: ‹ Encourage natural drainage. ‹ Where does the water come from? ‹ Encourage airflow under your house so ‹ How can I reduce the water getting moisture in the soil can evaporate. under my house? ‹ Add gravel under your house where ‹ How can I promote evaporation of water pools. the water?

13 Water Tank Overflow

If you have a water tank in your home, you should make sure the water tank overflow light is not burned out or missing. Overflow during your tank’s regular fill up can lead to water running down the side of the house. If overflow happens frequently, the spilled water can soon become a small lake or a skating rink under your house.

Ice and water under your house contributes to permafrost thaw and can cause piles and Frozen overflow from a water tank Photo credit: NWT Housing Corporation blocks to rot or rust. Water seeping under skirting can cause even more problems because the water does not get a chance to evaporate in the summer.

Here are a few simple solutions

Overflow from your water tank builds up ‹ Install a water tank overflow light (this can Photo credit: NWT Housing Corporation be costly and may require an electrician). ‹ Replace a burned out bulb if that is all that is required. ‹ Divert spilled water away from your house with a PVC pipe. ‹ Place a five-gallon bucket under the overflow and dump it away from the house. ‹ If you are home when the truck is filling your tank, flash your porch light when the tank is getting full.

Ice and water causes rotting of piles

14 Snow

Think of snow as nature’s blanket. Air spaces in snow act like the air spaces in a down quilt. This means a snow bank will keep the ground Tip much warmer than bare ground. Without a blanket of snow, permafrost will refreeze much Deep snow blocks winter’s frost from deeper and to a colder temperature. When snow penetrating into the ground, thus builds up under or around your house or you warming permafrost and preventing pile snow against the skirting to keep the floor it from reforming. Be aware of snow warm, you are robbing the permafrost of the patterns around your house. cold air it needs to freeze solid in the winter.

‹ Instead of banking snow around your house, try shovelling it away from your foundation. ‹ Let the cold winter air reach deep into the ground. This will help the permafrost under your house to freeze solid and make it harder for warm summer weather to thaw it. ‹ Don’t store anything under your house, Snowbanks hinder the cold from recharging permafrost during the winter this encourages snow build-up.

Storing materials under your house can encourage permafrost thaw

15 Wind

Tip

Good air circulation under your house allows moisture to evaporate in the summer and blows away snow in the winter.

Snowbanks do not allow the cold to recharge permafrost in the winter ‹ Help the wind blow away snow by removing obstacles to the wind. Managing snow is especially important in ‹ Can you build a windbreak or snowfence windy communities above the treeline. Without on the windy side of your house (at trees to block wind and collect snow, the wind least 4 metres away). will deposit snow drifts anywhere there is a low area or obstruction. These snow drifts increase the depth of the active layer and encourage seasonal frost action and permafrost thaw. If your house is in an area where snow builds up in the winter, the snow banks do not allow the cold to penetrate into the ground. Wind

Active Layer Deep snow insulates the ground in the winter, causing a deeper active layer, while areas blown free of snow have colder and thicker permafrost. Credit: Modified from Sladen Permafrost 16 Skirting

Skirting is the plywood covering around the foundation of a house. It is usually added to make the house look neater or to keep the Tip floors warmer in the winter. If you have skirting and are sure you live Houses built over permafrost are generally over ice-rich permafrost, consider the designed to be raised off the ground with open following general rules for the base of sides to promote airflow under the house. This airflow helps refreeze the permafrost in the your house: winter and encourages evaporation of moisture in the summer. Skirting limits evaporation ‹ Remove your skirting altogether and warms the air under the house leading This will help permafrost to re-establish to a slow degradation of permafrost. itself under your house. (Skirting should only be removed if you are concerned about permafrost degradation, as its removal may lead to an increase in heating bills.) ‹ If you can’t remove your skirting, think about adding vents to allow cold air access in the winter. ‹ Wire mesh around building foundations allows air to blow through and prevents kids from playing under houses or materials from being stored there. Skirting promotes permafrost thaw ‹ Do not store snowmobiles and lumber or keep dogs under your house. This practice promotes snow build-up that insulates the ground in the winter. ‹ If cold floors are a problem, add insulation under the floor. ‹ Don’t bank snow around your house in the winter. Wire mesh allows airflow but keeps foundation clear

17 Other Factors

Vegetation: Try not to disturb vegetation near your foundation, as dark exposed soil warms in the sun and causes permafrost to thaw.

Clothes Dryer Vents: Exhaust heat from clothes dryers can melt snow causing localized frost effects. It can also add extra heat to closed foundations and crawlspaces encouraging permafrost thaw. Properly installed clothes drier vents should be well off the ground on an outside wall and should not be vented into crawl spaces.

Removing native vegetation can cause permafrost to thaw

Tip

Shade

‹ The long days of sun in the northern summer, heat the ground and encourage permafrost thaw. Homeowners can provide shade to the southern side of their house, either through planting trees or shrubs, or by installing seasonal skirting on the southern side only.

Dryer vents should not be vented into crawl spaces

18 Heating Oil Tanks

Damages caused by a leak or spill in a home heating oil tank can lead to a very costly clean- up for an unfortunate homeowner. Therefore, it is in a homeowner’s best interest to inspect and maintain their heating oil tank regularly. Permafrost thaw under the tank or the house can cause movement and put enough stress on fuel lines to cause a break. Homeowners Flex hose helps prevent broken fuel lines should inspect their tank regularly to watch for signs of shifting and to ensure that it has a One way to help prevent shifting damage is to solid base, is not wobbly, and is not leaning. install a flexible connection, called a flex connector, between the fuel tank and the house. Flex connectors should be installed in a straight line and should be inspected routinely by the homeowner. If the flex connector becomes bent or is in an S-shape it indicates there has been movement of the tank or house.

More information on the maintenance and upkeep of heating oil tanks is available on the Environment and Natural Resources website at: www.enr.gov.nt.ca/_live/documents/ content/Homeowners_Guide_Oil_Tanks.pdf

A wobbly or leaning tank can cause a break in your fuel line Tip

Check your heating oil tank regularly:

‹ Is it leaning? ‹ Is it wobbly? ‹ Do you have a flex connector? ‹ Is your flex connector bent or straight? 19 Rotting Pilings?

The Town of Inuvik was built during the late 1950’s and early 1960’s. More than 70,000 local spruce logs were used as piles. These Tip piles were drilled 15 to 20 feet into the 300- foot deep permafrost. Do you have wooden pilings?

Building practices have changed since then ‹ Reduce water and snow from getting and today most new houses are built using under your house and encourage airflow more durable steel piles. However, old, often and evaporation in the summer to untreated, wooden piles still hold up many decrease the speed of rotting. houses throughout the NWT.

The lifespan of wooden piles is rated at 20 to 30 years but many have been around for much longer. If your house sits on wooden piles, make sure they are checked for rot. It may not be visible to the eye. Experts use a screwdriver or knife to detect soft spots in the wood. Wooden pilings rot over time in warm, moist conditions Rot is most common below ground level, where moist soil and air meet. Low-lying wet areas and houses with skirting, which can prevent soil from drying out in the summer, are most likely to have rot. Prevent any further deterioration of your piles by decreasing the moisture in the soil around them.

Steel piles have a longer lifespan but rust Rotten pilings put your foundation at risk and corrosion can have a similar impact. Good moisture prevention practices will make them last longer. More information on dealing with rotting or decaying wooden piles is available on the Public Works and Services website at: www.pws.gov.nt.ca/pdf/publications/ Deteriorated-Wood-Pile.pdf 20 Foundation Checklist!

These basic maintenance tips will help you keep your house and its foundation in good repair:

Level your house periodically if you are on a surface foundation. Clear snow from around the foundation so the ground can freeze more solidly. Check wooden pilings for rot. Reduce water and ice build-up under your house. Proper maintenance of your foundation is important for your house Clean your eavestroughs and extend your If you are a private homeowner it downspouts so they drain away from the house. is in your interest to maintain your If snow is drifting or piling up because of permafrost. Now that you understand the the wind, remove the cause of the build-up. basics of permafrost and how it affects your home’s foundation it is important Check the natural drainage during a that you do some basic maintenance to rainstorm. Is water flowing away from keep your house in good shape. your house or towards it?

Remove your skirting or add vents. Be aware, that removing the skirting may cause an increase in your heating bill. Only proceed if you are concerned about permafrost degradation. Try to reduce overflow from your water tank or, at least, divert it from under your house. Check your fuel tank. Do you have a flexible hose. Does the fuel tank show signs of tilting? Check to see if anything is stored under your Level your house annually house? If so can you store it elsewhere? Check that your drier vent is located on an outside wall. 21 In the Northwest Territories, many homes rely on frozen ground or permafrost to keep their foundation solid. Climate change Sources and Resources: along with improper house design and poor 1 Wolfe, Stephen. Living with Frozen Ground maintenance are leading to widespread A Field Guide to Permafrost in Yellowknife, permafrost degradation. NWT. Natural Resources Canada, Geological Survey of Canada M41-8/64E. Learn about permafrost, how it acts as part of 1998. your foundation and what you can do to keep it from thawing. A few minutes and some simple 2 Glossary of Permafrost and Related solutions could save you thousands of dollars Ground-Ice Terms, National Research and help keep your house on solid ground! Council Canada. 1988.

This booklet is only meant as a guide and 3 Hoeve, Ed. Assessment of Foundation if you are facing serious permafrost related Sensitivity to Climate Change in the Northwest Territories. problems with your home you should contact EBA Engineering. 2005. an expert. 4 Heginbottom, J.A. Dubreuil, M.A. and Harker, P.A. 1995. Canada – Permafrost, National Atlas of Canada, 5th Edition. Natural Resources Canada, . MCR 4177. Scale 1: 7,500,000 1995.

5 Short, N., Stevens, C.W. and Wolfe, S.A. 2011. Seasonal Surface Displacement Derived from InSAR, Yellowknife and Surrounding Area, Northwest Territories; Geological Survey of Canada, Open File 7030, 1 CD-ROM. doi:10.4095/289578

6 Sladen, W. E., 2011. Permafrost; Geological Survey of Canada, Open File 6724, 1 Sheet. Doi: 10.4095/288000

Permafrost issues can be complicated; sometimes it’s 7 Homeowner’s Guide to Oil Tanks, necessary to ask an expert Environment and Natural Resources 2010: www.enr.gov.nt.ca/sites/default/files/ brochures/homeowners_guide_oil_tanks.pdf

8 Deteriorated Untreated Wood Piles: Cause Detection and Correction pamphlet, Public Works and Services: www.pws.gov.nt.ca/pdf/publications/ deteriorated-Wood-Pile.pdf For more information on climate change adaptation visit www.nwtclimatechange.ca ISBN 978-0-7708-0198-4