Climate Change Impacts on Water and Wastewater Systems in the Arctic Kenneth Johnson, M.A.Sc., RPP, FCAE, P.Eng. Planner, Engineer, and Historian Cold Regions Specialist Funding for this report provided by NRC and INFC through the Climate Resilient Buildings and Core Public Infrastructure Project, as part of the Pan Canadian Framework on Clean Growth and Climate Change 1.0
Introduction
1.1
Background
2017-03-30
Many factors influence engineering practices associated with water and sewer infrastructure in Canada's Arctic. These factors include the extreme cold conditions that infrastructure must withstand, ground related conditions, the short construction season, challenges of transporting construction material, delays in procuring specialized equipment, and an undersupply of labour. Water and sewer infrastructure systems in Canada's Arctic are uniquely vulnerable compared to southern infrastructure systems. Permafrost and other ice related issues are fundamental considerations for the infrastructure design, construction, operation and maintenance. Construction and operating costs are high due to distance and isolation plus the extreme cold and infrastructure deteriorates rapidly in extreme environments. Experience in Canada's Arctic shows that, even after a brief interruption in operation, reopening infrastructure tends to be costly. The existing infrastructure deficit, the lack of options and ""backups"' in infrastructure services, and capacity constraints in the form of finances and human resources are all relevant issues associated with northern infrastructure. The impact of the climate change on the Arctic region of Canada is affecting community infrastructure, and in particular water and wastewater systems. There are limitations in current approaches to design, construction, both new construction and rehabilitation construction of Core Public Infrastructure (CPI) that are based on past climatic loads and not on expected future climatic loads. Future climatic loads may lead to early failure of CPI, long service disruption, high rehabilitation and replacement costs, and considerable negative socio-economic impact. The consequences of failure of existing and new CPI are quite significant, particularly in the far north because infrastructure has additional stresses associated with cost, geography, extreme climate, and operation maintenance limitations. The National Research Council of Canada (NRC) and Infrastructure Canada (INFC) are leading a group to develop decision support tools, including codes, guides and models for the design of resilient new Canadian core public infrastructure (CPI) and rehabilitation of existing CPI. The objective is to make sure there is an inherent capacity against existing and future climate change and extreme weather events through various engineering, and facility management tools, and opportunities. 1.2
Scope of Work
The report addresses the potential impact of climate change related to water and waste water systems in the Arctic. This report, along with those produced by NRC staff, will be compiled into a summary document that identifies the key knowledge gaps that need to be addressed to make sure Canada’s Arctic water and waste water systems are resilient to the effects of climate change. The results of the gap identification may be used to provide guidance for future research activities.
1
The scope of work of this report includes: •
A brief description of the broad view about the potential impact of climate change upon northern water and sewer system components.
•
A description of the current state of practice as it relates to climate phenomena impact on northern water and sewer system component.
•
A detailed description of potential specific impacts of climate change on northern water and sewer system components.
•
Identification of knowledge gaps that need to be addressed through research to better understand potential CC impacts on northern water and sewer system components, and potential practices, measures, tools, materials and/or products that would be useful in increasing CC-resiliency.
•
Presentation of case studies related to Climate Change Impacts on Water and Wastewater Systems in the Arctic presented in Appendix (Articles from Journal of the Northern Territories Water and Waste Association).
2.0
Broad View of Potential Impacts
2.1
Frozen Ground
Much of the infrastructure in Canada's Arctic relies on permafrost, snow, and ice for its stability and utility. For example, containment structures, often rely on the integrity of permafrost to prevent leakage, and movement because frozen earth material has a low permeability and a stronger load-bearing capacity relative to non-frozen ground. However, about half of Canada’s permafrost zones are moderately or highly sensitive to thawing in warmer climate conditions, permafrost terrain with high water content being particularly susceptible to rapid deterioration if disturbed by water. In Canada's Arctic, accounting for the physical state of permafrost and other frozen systems in the design, construction, and maintenance of infrastructure is an engineering challenge, and experience has led to a variety of practices and technologies adapted to the Arctic. In the design, construction, operation and maintenance of water and sewer infrastructure , engineering relies on environmental data, such as weather and climate data, and in some cases customized climatic design values supplied by the Government of Canada. Often, practitioners make adjustments to account for observed trends, assumptions about expected environmental changes, and related site-specific implications for permafrost and ice systems. Engineering strategies to date favour maintaining frozen conditions and limiting thaw in order to maintain a low permeable state constrain infrastructure movement to within tolerable Levels. The choice of foundation and overall design is therefore a function of both infrastructure loads and thermal conditions of the ground. 2.2
Construction and Maintenance
The relatively sparse population, remote geography, weather-dependent construction season, and high costs of labour and materials make northern infrastructure construction, operation and maintenance potentially very expensive. Constraints in capacity that prevent timely maintenance and replacement of infrastructure can also contribute to long-term costs. For example, a lack of local capacity to maintain or repair technical equipment in some communities means that maintenance may occur less regularly than should be the case. Failures can result in prolonged interruptions in service partly due to the limited supply of technical expertise. In many cases, construction material comes from outside the Arctic, as does specialized equipment. Due to either climate-related phenomena, regulatory changes, or increased rates of use, enhanced maintenance efforts add to the cost of services delivered by infrastructure. In some cases, service continuity is a business driver and changes in operating environments, including 2
changes in weather patterns, can provide an incentive to make incremental adjustments in infrastructure management. 2.3
Attributes of Infrastructure Not Suited to Change
The water and sewer infrastructure in the Canadian Arctic north has three significant attributes relevant to climate change. The attributes are: design life; a non-portable configuration; and a complexity of design, and operation and maintenance. The design life attribute means that the infrastructure is designed to last a generation, or 20 to 30 years, which means that a community is burdened with whatever infrastructure is built for a 20 to 30 year period, with limited or no opportunity for changing the infrastructure. The nonportable attribute means that the infrastructure has a fixed location with no possibility for moving. The final attribute is associated with complexity of design, and operation and maintenance means that the infrastructure means that the issues associated with the 20 to 30 year operating life will generally not be simple or inexpensive. All of these attributes are directly connected with the natural environment in the north which is harsh, isolated, and dynamic. These three attributes do not align well with climate change because by its very nature of creating an increasingly dynamic natural environment, the water and sewer infrastructure must respond in its day to day function. This is difficult enough with “normal” the day to day function of infrastructure in the Arctic, and quite likely difficult to impossible with the changes to come. A changing climate presents additional challenges to the design, development, and management of infrastructure in the Arctic. Physical infrastructure is "'climate sensitive" because it is designed, built, and operated to provide useful service over decades within a prescribed range of site specific climate and environmental conditions. The current stock of physical infrastructure and that built in the next few decades will be subject to climate conditions outside of historical experience, with changes likely intensifying over time. All infrastructure systems carry some risk of failure. However, unanticipated, and rapid changes in their operating environment can increase this risk and overwhelm systems' coping capacity, with related financial losses, health and safety risks, and impacts on ecosystems. 2.4
Climate Impacts, and Potential Reponses for Water and Sewer Infrastructure
Water and sewer infrastructure in the Arctic each have a number of components and within each of these components are a number of elements. For example, the water source may utilize a river, a lake or ground (See Tables 1 and 2). For each of these components and elements there may be climate related impacts. For example, the water source may be impacted by water quality and water quantity issues. In response to climate impacts on the various elements of water and sewer infrastructure resiliency may be more appropriate that redundancy. Historically, the application of redundancy has meant having “more of the same” to be in a position to response to critical facility issues, whereas “resiliency” refers to the ability of such infrastructure systems (including the interconnected systems and the social systems) to absorb disturbance and still retain their basic function and structural capacity.
3
Table 1. Water Infrastructure – Components, Impacts, and Responses Components Source
Elements - River - Lake - Ground
Climate Impacts Water quality Water quantity
Potential Responses - resilient water treatment systems for changes in water quality - resilient water supply sources for reductions in water quantity
Raw Water Intake
- Pipe - Gravity - Pumping
Water quantity Water - River freeze up and breakup
- resilient water intake systems for reductions in water quantity or damage to water intake systems
Raw Water Storage
-
Ground - Facility foundation
- resilient foundation systems for changes in ground conditions
Water - quality Ground – Facility foundation
- resilient water treatment systems for changes in water quality - resilient foundation systems for changes in ground conditions
Treatment
Earth Reservoir Rock Reservoir Steel Tank Concrete Tank Filtration Disinfection
Treated Water Storage
- Concrete Reservoir - Steel Reservoir
Ground - Facility foundation
- resilient foundation systems for changes in ground conditions
Distribution
- Trucked - Buried Piped - Utilidor Piped
Ground - Buried pipe Ground - Utilidor pipe Ground - Access roads
- resilient designed systems for buried water and sewer systems - adequate drainage systems for roadways
Table 2. Wastewater Infrastructure – Components, Impacts, and Responses Components Collection
Preliminary Treatment
-
Elements Trucked Piped Bagged None (latrine) Lagoon Mechanical
Primary Treatment
- Lagoon - Mechanical
Secondary Treatment
- Lagoon - Mechanical
Supplementary Treatment
- Lagoon - Mechanical - Wetland
Discharge System
-
Discharge Location
Outfall Surface River Lake Ocean
Climate Impacts Ground - Access Roads Ground – Buried Pipe Ground - Utilidor pipe Ground - lagoon Ground- building foundation Ground - lagoon Ground- building foundation Ground – lagoon Ground – building foundation Ground - lagoon Ground – building foundation Weather – wetland operation River freeze up and break up River quantity Lake quality
Potential Responses - adequate drainage systems for roadways - resilient designed systems for buried water and sewer systems - resilient earth systems for lagoons - resilient earth systems for lagoons - resilient foundation systems for changes in ground conditions - resilient earth systems for lagoons - resilient foundation systems for changes in ground conditions - resilient earth systems for lagoon systems - robust foundation systems for changes in ground conditions - resilient discharge systems for damage to sewage discharges - alternate discharge or increase treatment to accommodate decreased capacity in receiving water
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3.0
Past and Present Status of Practice
3.1
Historical Response of Water and Sewer Infrastructure to Change
The historical response of water and sanitation to change has been the application of redundancies in facilities. For example, back up generating systems were a luxury for water and sanitation infrastructure 30 years ago, and are now a necessity. The lack of system "redundancies" or backups and isolation of many communities are key features that differentiate infrastructure systems in the Arctic from those of more densely populated parts of the south. In the event of infrastructure failure, some northern communities may not have access to backups or alternatives that many southern communities take for granted, such as an alternate roads for facility access, piped and looped water systems, and grid connectivity to other power stations. This lack of options can lead to emergency situations that require the mobilization of considerable resources at great expense to address the issue. 3.2
Current Response to Climate Change and Water and Infrastructure
Good Engineering Practice (GEP) for Northern Water and Sewer Systems were originally published in 2004 by the Department of Public Works and Services, GNWT. Revisions for Second Edition are in progress with input solicited from a broad range of government and consulting practitioners. The new edition of the GEP has the following introduction: “Northern conditions often require a different approach to design than what is commonly used in Southern Canada. This section introduces some Northern-specific challenges and conditions. It is intended to highlight some of the differences between Northern and Southern areas, but is not comprehensive and is not a substitute for experience, research, and site-specific investigations. There are a number of textbooks available on frozen ground engineering and permafrost. Designers should ensure that they are familiar with the issues pertinent to their discipline or area of expertise.� The new edition of GEP currently has no explicit mention of climate change influences or considerations associated with the planning, design, construction, and operation and maintenance of water and sewer infrastructure. There are planning reports addressing climate adaptation that have been developed for many Arctic communities, but water and sewer infrastructure is only highlighted in the context that change will likely occur and adaptation will be needed. Therefore, any explicit consideration of climate change in the planning, design, construction, and operation and maintenance is left to the individual designer , builder and the community. 4.0
Specific Impacts of Climate Change on Water and Sewer Infrastructure
A detailed compilation of specific occurrences of potential climate change issues on northern water and sewer system components are presented in Table 3, with the issue and the response. More details are provided on four of the occurrences are presented in articles in the appendix. Water supply and treatment amount to 11 of the 18 occurrences, and 7 of the occurrences are associated with water quality. Water and sewage conveyance amounts to 4 of the 18 occurrences. Sewage treatment amounts to 3 of the 18 occurrences, and all of the occurrences are associated with lagoons leaking. The detailed descriptions are presented for water supply and treatment occurrences in Kugaaruk , Grise Fiord, Yellowknife, and Arviat, Kugaaruk. The detailed descriptions are articles in the Northern Territories Water and Waste Journal (edited by Ken Johnson) and the Western Canada Water magazine (editorial committee includes Ken Johnson). 5
5.0
Knowledge Gaps
A compilation of issues and knowledge for water and sewer infrastructure in the Arctic with its components and elements are presents in Tables 4 and 5. Issues and knowledge gaps have been presented for water and sewer infrastructure for the purpose of developing research opportunities to better understand potential CC impacts on water and sewer system components in the Arctic. For water infrastructure there are knowledge gaps for each issues concerning the components and elements. A common factor in the knowledge gaps is the potential need for “Standards and Criteria�, which is being advanced to some degree with the updating of the document on Good Engineering Practices. For sewer infrastructure there are knowledge gaps for each issue concerning the components and elements. A common factor in the knowledge gaps in the absence of information. Although consideration information has been gained in the past five years, the information to address various issues is still lacing. 6.0
Conclusions and Recommendation
Climate change is apparently emerging as an issue for water and sewage infrastructure in the Canadian Arctic. In general, it is anticipated that the warming Arctic climate in Arctic will influence the quantity and quality of water that is already in short supply for community use. The abundant water in short supply in the Arctic is looking to a future with technical innovations that will provide systems that are robust and resilient to the extreme water issues in the North.
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Table 3. Occurrences, issues, and responses potentially related to climate change, and water and sewer Occurrence Issue Water Supply / Treatment Cambridge Bay water Apparent change in raw water quality supply from original design criteria Sanikiluaq water supply Change in water quality (coliforms and salt water intrusion in water supply lake) Kugaaruk water supply Change in water quality ( salt water intrusion up water supply river) Kugluktuk water supply Change in water quality (salt water intrusion up and sediment in Coppermine river Grise Fiord water Change in water quantity (glacier melt supply resupply diminishing) Yellowknife water Change in water quality (Yellowknife supply River turbidity events, and low water flows) Arviat water supply Change in water quantity (reservoir leak and storage reduced) Tuktoyaktuk water Change water quantity (water level supply reduction in seasonal water supply lake) Whale Cover water Change in water quality (coliforms in supply water supply) Igloolik water supply Change in water quality (coliforms in water supply) Fort Providence water Change in quantity (water intake supply blockage from ice) Sewage Treatment Kugaaruk sewage Lagoon leaking treatment Kugluktuk sewage Lagoon leaking treatment Cape Dorset sewage Lagoon leaking treatment Water and Sewage Conveyance Dawson City sewer Historical problem with sewers sagging system
Response Process changes may be needed to accommodate change in raw water New water treatment facility planned Alternate water supply identified and utilized as required (See Ref Article in Appendix) New water treatment facility and intake completed Hydrology studies undertaken (See Ref Article in Appendix) New water treatment facility and intake completed (See two Ref Articles in Appendix) Emergency water treatment system mobilized (See Ref Article in Appendix) Ongoing observations Boil water orders in place as required; water treatment planning Boil water orders in place as required; water treatment planning Planning for new intake Site investigation and remedial plans developed Site investigation, remedial plan developed and executed Site investigation and remedial plans developed
Iqaluit sewer system
Historical problem with sewers sagging
Fort Simpson water system Inuvik utilidor system
Water line breaks
Comprehensive sewer study completed and 20 capital plan developed (See Ref Article in Appendix) Design standard developed and implemented as required Repair as needed
Stability of utilidor deteriorating due to warming of permafrost
Need for deeper piles or some other foundation system
General Notes: 1. Communities along Yukon and Mackenzie Rivers may experience a change in water quality attributed to changes in freshwater chemistry that are being attributed to thawing permafrost, for example, minerals that had been locked in permafrost, such as calcium, magnesium, and sodium, as well as sulfate are making their way into the river water.
7
Table 4. Water Infrastructure – Issues and Knowledge Gaps Components Source
Elements - River - Lake - Ground
Raw Water Intake
-
Raw Water Storage
Piped System Gravity Conveyance Pumping Conveyance River Source Lake Source Ground Source Earth Reservoir Rock Reservoir Steel Tank Concrete Tank
Treatment
- Filtration - Disinfection
Treated Water Storage
- Concrete Reservoir - Steel Reservoir
Distribution
- Trucked - Buried Piped - Utilidor
Issues Alternative water sources for communities - note – GN completed a study of alternative water sources for all NU communities but the result was “unsatisfactory” Systems damaged by ice related factors in lakes and rivers – note - intakes have evolved the over the past 30 years on a case by case basis
Knowledge Gaps Local studies of alternative water surface or ground water supplies and surface water hydrology Studies of alternative water supplies in permafrost environment Alternative intake systems for river and lakes for ice related conditions Potential need for Standards and Criteria, for example, GNWT Good Engineering Practices
Raw water storage systems have evolved over the past 30 years on a case by case basis – earth reservoirs are the most commonly used for communities with seasonal water supplies All communities in Yukon and NWT have multi barrier water treatment systems – 14 of 25 Nunavut communities have multi barrier water treatment systems and the remainder have just chlorination
Alternate configurations and materials for raw water storage Potential need for Standards and Criteria for example, GNWT Good Engineering Practices
Water storage in communities on trucked water supply generally are deficient with regard to fire fighting capability concerning quantity and delivery Piped water systems are used in a limited number of communities – systems are expensive (capital cost) but generally have no performance issues Trucked water systems have issues associated with disinfection of in house storage tanks, and delivery interruptions associated with equipment breakdown and road access
Performance of simpler filtration technology (cartridge filtration) in north Performance of complex filtration technology (membrane filtration) in north relating to costs (capital and o+m) and human resource needs Fire science and building alternatives for northern communities - note - most recent study completed in 1993 – “NWT Fire Protection Study 1993” Standards and Criteria for piped delivery systems expressed in GNWT Good Engineering Practices, reflecting general practices for systems – note – update of GEP in progress with input from consulting community No significant innovations in past 35 years
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Table 5. Wastewater Infrastructure – Issues and Knowledge Gaps Components Collection
-
Elements Trucked Piped Bagged None (latrine)
Preliminary Treatment
- Lagoon - Mechanical
Primary Treatment
- Lagoon - Mechanical
Secondary Treatment
- Lagoon - Mechanical
Supplementary Treatment
- Lagoon - Mechanical - Wetland
Discharge System
- Piped - Pumped - Submerged outfall - Surface outfall -
Issues - Piped sewage systems are used in a limited number of communities – systems are expensive (capital cost) and have performance issues with sagging - Trucked sewage systems have issues associated with delivery interruptions associated with equipment breakdown and road access - Preliminary treatment is generally not associated with lagoon systems - Preliminary treatment with a mechanical system has no operating systems in the north - Primary treatment only probably unacceptable to regulators - Lagoon systems performance issues associated with weather (effluent quality), and retention (lagoons leaking) - Mechanical systems cost issues and performance issues associated with operating resources (cost and human resources) - Primary treatment only probably unacceptable to regulators - Lagoon systems performance issues associated with weather (effluent quality), and retention (lagoons leaking) - Mechanical systems cost issues and performance issues associated with operating resources (cost and human resources) - Lagoon and wetland systems performance issues associated with weather (effluent quality), and retention (lagoons leaking) - Mechanical systems cost issues and performance issues associated with operating resources (cost and human resources)
- Piped discharge systems have issues with freezing - Pumped discharge systems are the preferred discharge configuration in permafrost regions - Submerged versus surface outfall to address discharge mixing
Knowledge Gaps - No innovations or increments in sewer design for resilience in the past 20 years – note – innovation in Dawson City (1993 - application of CMP jacket to strengthen pipe against ground subsidence) – innovation in Iqaluit (1997 - application of Insulating barriers around pipe to maintain permafrost and eliminate seasonal freeze back pressures) - Preliminary treatment is generally not associated with lagoon systems - Preliminary treatment with a mechanical system has no operating systems in the north - Limited information on performance of primary lagoons in arctic conditions - Limited information on performance of geomembrane systems for earth lagoons in an arctic environment - Limited information on performance and costs of mechanical systems - Limited information on performance of secondary lagoons in arctic conditions - Limited information on performance of geomembrane systems for earth lagoons in an arctic environment - Limited information on performance and costs of mechanical systems - Limited information on performance of supplementary systems in Arctic conditions
- Use of pumped discharge systems evolved from observed performance of piped discharge systems – no design standard - based upon client/consultant preference -
9
Components
Discharge Location
Elements
- River - Lake - Ocean -
Issues
- Regulatory issues associated with discharge location - Community issues associated with discharge location
Knowledge Gaps - Very limited information on
impact of sewage effluent on arctic environment
The priority for climate change research should be water supply and treatment because of the majority of the occurrences presented in this report. Sewage and conveyance have the same, but a lower priority. As challenging as "normal" water supply is in Arctic, there are several examples of extreme water use issues. In Grise Fiord, the stream that fills the water reservoirs on an annual basis dried up during one filling season, and the community ran out of drinking water before the reservoir could be refilled in the spring. The community resorted to harvesting icebergs, and chopping and placing the ice into the reservoir to maintain the water supply. Most northern communities have limited capacity for dealing with water and sewage, whether it be financial, administrative or human resources. Contrary to this limited capacity are increasing demands for finance, administration and human resources being driven by increasing regulatory demands and increasing sophistication in the technology associated with water for treatment of drinking water and waste water. These types of infrastructure are, in some cases, lifelines for northern communities, providing the basic services of mobility, shelter, connectivity, power, and protection from pollution. Combined, these services also enable effective responses to emergencies.
10
APPENDIX REFERENCE ARTICLES Kugaaruk, Nunavut Water Supply and Alternative Water Supply Study Water Supply Challenges in Grise Fiord, Nunavut Major Water Treatment Improvements for Yellowknife, NWT Drought in the Far North Emergency Water Supply System for Arviat, Nunavut Dawson City’s Sanitary Sewers - Assessment and Remediation Planning
11
H Kugaaruk NUNAVUT
Kugaaruk, Nunavut Water Supply, and Alternative Water Supply Study FIGURE 1. The mechanism for salt water intrusion into a freshwater supply.
SUSTAINING communities for over
30 Years.
Every day in the Northwest Territories and Nunavut, NAPEG Members play an important role in developing innovative and sustainable water supply and treatment solutions. To learn more, visit www.napeg.nt.ca
NAPEG Northwest Territories and Nunavut Association of Professional Engineers and Geoscientists 201, 4817 - 49 Street, Yellowknife, NWT X1A 3S7
(867) 920-4055
30
The Journal of the Northern Territories Water & Waste Association 2013
Salt water intrusion into community drinking water supplies is not a new phenomenon, and in fact, it was been regularly occurring in Kugluktuk, Nunavut for decades. Salt water intrusion is the result of tidal action which pushes seawater in a wedge up a freshwater river (See Figure 1). If the freshwater supply intake is reasonably close to the ocean, the wedge may migrate to the intake, making the water supply unusable. In Kugluktuk, despite various past efforts to solve the intake of seawater and sediment from the Coppermine River, murky brine flowing from the community’s taps has been the norm during the river’s fall freeze-up and spring break-up periods. A solution to the Kugluktuk water supply problem has been underway for several years (see article NTWWA Journal 2011). Salt water intrusion is also a problem for the community of Kugaaruk in Nunavut. The name Kugaaruk means “a river flowing through a community used for fishing and to supply water.” Formerly known as Pelly Bay, Kugaaruk is located on the Simpson Peninsula, south of the Gulf of Boothia, and is home to some 830 people. In November 2011, the Hamlet of Kugaaruk was advised of contamination of their fresh water supply. Salt water intrusion wedged its way more than 2.5 kilometres up to the water intake on the
By Ken Johnson, Senior Planner and Engineer, Stantec Consulting Ltd., Edmonton
Kugaaruk River adjacent to the community. The water delivery continued for some time after the intrusion occurred and many of the water storage tanks and water trucks were filled with salty water. Tests indicated that the drinking water had a salt content four to five times over accepted guidelines. The initial response to the crisis was the hiring of several people by the hamlet to haul water from a lake about 11 kilometres outside of town. Water was hauled using snowmobiles with kamotiks and large water containers (See Figure 2). The water was kept in large containers in the fire hall, where people could pick it up. The fresh water is also delivered to elders and others who could not pick up water on their own. A concurrent response to the crisis was the hiring of contractors by the Government of Nunavut (GN) Department of Community and Government Services to build an ice road to a point two kilometres further up the Kugaaruk River, where it was anticipated that the wedge had not migrated. The community built a temporary pump house (See Figure 3), and the water supply was restored. However, since this temporary system was built on ice, this supply would only last until the river broke up in June. After break up, it was anticipated to deliver salty water from the permanent intake to homes for use in things like washing or flushing the toilet. After the river intake was taken out of service with break up, the drinking started coming from a body of water that local people call “Swimming Lake”. Ultimately, it was anticipated that once the flow in the river increased after breakup, the water intake would be flushed of salt and the community could go back to the permanent pump house
Kugaaruk NUNAVUT
and water supply. However, this emer-
managed to flush out the salt water from
gency brought to light that the people in
the drinking water intake on the river.
Kugaaruk, Nunavut could face uncertain-
ty with their drinking water, even months
supply issues in Kugluktuk, Arviat, Grise
after the tidal surge occurred. With
Fiord, Cape Dorset, and Cambridge Bay,
spring runoff that year, the river, in fact,
identified the need for a GN initiative to
This event, along with other water
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This event identified the need for a GN initiative to identify alternate water sources for communities.
Kugaaruk NUNAVUT
FIGURE 2. Hauling water by komatik in Kugaaruk, and storage in the community fire hall.
identify alternative water sources for communities in the event that main water sources or related infrastructure goes out of service: • Kugluktuk and Kugaaruk have issues with salt water intrusion into the water supply; SUPPORTING MAJOR PROJECTS IN AB, MB, NW ON, NWT & NUNAVUT
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FIGURE 3. Temporary truckfill station built in Kugaaruk.
• Arviat has an issue with the stability of the water supply reservoir; • Grise Fiord has an issue with water supply quantity for the annual reservoir filling; and • Cape Dorset and Cambridge Bay have issues with freeze up of the water supply main. This study was initiated in 2012 and is scheduled for completion in in 2014. The first phase of the project was a desktop study which involved identifying, reviewing and compiling any and all background data on potential community water supplies, along with community interviews. This phase is anticipated to deliver a substantial amount of background information, since most communities in Nunavut have had water supply planning studies completed, which generally provide a significant number of alternate water supplies. Phase 2 of the study will encompass site visits to verify and update the compiled information recognizing that a lot of the compiled information will be decades old. The majority of the site visits will be completed in the spring and summer 2013. The final phase of the study will be the report preparation that will incorporate the current site information into the compiled background information. The water supply emergency in Kugaaruk was successfully tackled through multi-faceted cooperation of various levels of government and through the efforts of the community applying technologies old and new. This problem will occur again, and the knowledge and experience gained from the first emergency will pay off.
References:
• Williams Engineering. Presentation at NTWWA Annual Conference. November 2012. • CBC News. “Kugaaruk working to restore fresh water supply.” January 9, 2012. • CBC News. “Hamlet officials hopeful that spring run-off will clear out salty water.” April 2012. S
The Journal of the Northern Territories Water & Waste Association 2013
GRISE FIORD
WATER SUPPLY CHALLENGES IN GRISE FIORD, NUNAVUT Grise Fiord is Canada’s most northern community at 76° 25’ 08” North latitude, a mere 1500 kilometres from the North Pole. Grise Fiord must be differentiated from the weather stations and stations further north such as Eureka and Alert because it is the permanent home to 140 Canadians. Community infrastructure is tough to maintain at this latitude, and it was made
“tougher” in spring of 2008, when residents of the community were forced to use icebergs as their potable water supply as they dealt with a severe water shortage. Grise Fiord must replenish its water supply during a brief 3 week window in the summer when glacier melt flows sufficiently to fill several large tanks with capacity enough to supply the communi-
Location of water tanks and season water supply in Grise Fiord. ty for 12 months. The tanks must then be heated at considerable expense for almost 12 months. Coupled with a population base that is too small to absorb the same base infrastructure costs borne in other communities, Grise Fiord has some of the highest water costs in the country with a rate of approximately 4.5 cents per litre. The cost of water in Ottawa is approximately 0.1 cents per litre – water in Grise Fiord is about 45 times more expensive than Ottawa.
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Journal of the Northern Territories Water & Waste Association 2008
GRISE FIORD
Harvesting ice blocks from iceberg using a loader.
This water shortage has happened to
the Hamlet’s 5.9 million-litre reservoir was
the community before in 1997, and 2000.
being depleted faster than usual. The sec-
In 1997 the Hamlet placed residents on
ond tank stood empty because the river
half-rations of water in a bid to stretch
froze at the end of the summer in 1996,
dwindling supplies into midsummer.
before it could be filled.
Conservation efforts began in April after
Up to the late 1970’s iceberg ice was the
community’s sole water supply from late September through June. At a community meeting in 1975 the community council was asked what water supply improvements they would like to see. The council replied, through an interpreter, that they would like some more of a certain tool that they had found in the school that they found to be ideal for harvesting chunks of ice off icebergs. Unfortunately the tool had been lost and they had no name for the device. After much discussion is was determined that the tool was a fire axe - the engineering consultant at the time, who was doing a water supply study, sent them two fire axes. Thirty years later, the community was once again reverting to this “old technology” for an interim potable water supply. The community would normally have the two huge water tanks filled with glacial
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Hauling ice blocks to community 6 kilometres away.
GRISE FIORD
Loaders were used to break blocks from the iceberg and haul them into the community, where four people chipped them into smaller pieces and put them into the tanks. It was estimated that the essential endeavour would cost about $60,000.
runoff to last them for 12 months from the
Grise Fiord officials issued an advisory
tank filling in June of each year. Un-
urging residents to conserve water, while
fortunately maintenance work and a lack
a six-kilometre ice road was built to the
of rain in the summer of 2007 left the
Hamlet's new water source — a massive
tanks under-filled.
iceberg. Loaders were used to break
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Journal of the Northern Territories Water & Waste Association 2008
GRISE FIORD should the problem recur. Climate change may become a factor in their situation, which they never foresaw a few years ago when we built these tanks. As well, the community may have to look for another source of water from other than the glacial runoff. It is interesting to note that for some of the residents, iceberg water is the preferred source of potable water, particularly for making tea because of the absence of chemicals. Each autumn as the ocean freezes, icebergs become trapped in pack-ice three or four kilometres from the Breaking up ice blocks by hand to place in the water tank.
Hamlet. Blocks of fresh-water ice may be hacked away with an axe or chisel, and
blocks from the iceberg and haul them into the community, where four people chipped them into smaller pieces and put them into the tanks. It was estimated that
the essential endeavour would cost about $60,000. The lack of water has also prompted residents to wonder what would happen
Journal of the Northern Territories Water & Waste Association 2008
carried back to the settlement in qamutiks (sleds), towed behind snowmobiles. One qamutik-load equals about 410 litres of water.
39
YELLOWKNIFE NORTHWEST TERRITORIES
H
Major Water Treatment Improvements for Yellowknife, NWT The City of Yellowknife is nearing the anticipated commencement of construction of a new, potable Water Treatment Plant (WTP), a process that started over ten years ago in 2002. Originally the city drew its water from Yellowknife Bay. At that time there were concerns with arsenic in the water column due to the ore processing techniques at both Giant and Con mines, and concerns with the discharge of sewage from Niven Lake into Back Bay. To address these concerns, the City, in conjunction with the federal government, constructed the current Yellowknife River water intake and pumphouse, and underwater pipeline
in 1969. Since this time, the city has drawn raw water from the Yellowknife River and provides simple chlorination as the only form of treatment on the source. The City has had growing concerns over seasonal turbidity spiking in the river and is therefore in the process of considering the alternatives available to them either for enhanced treatment of the river source, or switching back to the bay source, or both. The main water quality concerns posed by either source are predominantly due to the aesthetics of increased turbidity during spring runoff (See Figure 1), and the interference this imposes upon the
achievement of effective disinfection. A lesser concern at this time, although one which the city considers a potential risk, is the level of arsenic in the lake source water. Since the 1960s, the Con mine switched to an Autoclave gold extraction process and recently shut down entirely, and the Giant mine shut down eliminating the original sources of arsenic contamination. Presently, raw water arsenic levels are well below present and anticipated future regulatory targets, and given maintenance of the status quo are not expected to increase. The City retained AECOM in 2002 to conduct an analysis of raw water quality and proceed with a pilot treatment plant process to determine which technology would best meet the needs of the city. Two main candidate process trains were considered viable: • “Conventionalâ€? treatment, based upon granular media filtration. For a source of low turbidity year round (even during spiking events, raw water turbidity rarely exceeds 10 NTU), it was considered that so-called direct filtration was a suitable treatment alternative, i.e. coagulationflocculation-granular media filtration, with no clarification pre-treatment. FIGURE 1. Sediment in the flow of the Yellowknife River periodically occurs and the new water treatment plant has the capability of removing it.
10
The Journal of the Northern Territories Water & Waste Association 2013
By Chris Greencorn, Director of Public Works and Engineering, City of Yellowknife
• Membrane filtration – use of low pressure micro- or ultra-filtration membranes for filtration of the water. Such membranes, composed of engineered polymeric fibres with tightly defined pore sizes, act as a physical barrier to the passage of particulate matter and pathogens, and can achieve a high degree of treatment in a single stage, often without any pre-treatment (under good raw water quality conditions). A preliminary design report was completed to evaluate feasible options for water supply, including water treatment processes and raw water source, to provide a basis for future design. Using the population growth trend and historical water consumption of the city, it has been determined that the new WTP will require a capacity of 20 ML/d to meet the projected maximum daily demand for the next 20 years (to 2029). This capacity was made on the basis of using the existing service water reservoirs to address the predicted peak hourly flows of 30 ML/d. Recommended water quality objectives for the city’s new WTP were created based on present Guidelines for Canadian Drinking Water Quality (GCDWQ), that were accepted as legislation by the Government of the Northwest Territories in 2009, as well as several drinking water regulations promulgated by the U.S. Environmental Protection Agency (USEPA). The report concluded, based upon the future population growth, tightening of water supply regulations and the overall operational and economic benefit of each option, that the application of a membrane filtration system is the best fit with regards to water treatment for the City of Yellowknife. With the application of Yellowknife Bay as the raw water source, the option to provide arsenic treatment is advisable and must be included in the subsequent design steps. However, after public consultation, the decision was made to retain the Yellowknife River as the city’s water source. With
YELLOWKNIFE NORTHWEST TERRITORIES
all these decisions in place, the detailed de-
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YELLOWKNIFE NORTHWEST TERRITORIES
FIGURE 2. The site of the new water treatment plant is along the shore of Yellowknife Bay between an existing pumphouse (on the left) and an existing reservoir (on the right).
project will have shop drawings and details already complete for the membrane plant, they will simply need to notify PALL when to start production of the membrane plant. This also allowed a custom design of the water treatment plant build around the details of the PALL treatment system. It is anticipated that this process will greatly reduce construction change orders due to an unknown element such as the membrane treatment process. The detailed design process was completed in May 2013, with the new wa-
ter treatment being located adjacent to the existing water reservoirs at the Pumphouse #1 site along Great Slake Lake. Parts of Pumphouse #1 and the reservoir will be incorporated into the new plant. The construction tenders closed on July 10, 2013, and three tenders were received on the project, with the lowest tender from Ontario-based NAC Contractors Ltd. for a total amount of $30,280,950. Two Northern companies bid for the contract, including Det’on Cho Nahanni Construction Ltd. and Clarke Builders, which put in
bids of $30,978,876 and $31,153,755 respectively. The City of Yellowknife has officially awarded the contract to NAC contractors, and the project is scheduled to be completed in 2015.
It will be the first, large scale, water
treatment plant in the Northwest Territories, equipped with a training room where the City of Yellowknife hopes to be a community partner in training new treatment plant operators from communities across the north. S
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The Journal of the Northern Territories Water & Waste Association 2013
A Climate of
CHANGE
Drought in the far north Ken Johnson, Stantec
Drought is a term that does not seem to be appropriate for the far north of Canada because of its seemly endless winters with snow, ice and perpetual cold. In fact, however, the north has the characteristics of a desert, with the average precipitation in Yellowknife being 250 mm per year, which officially puts it on the cusp of being a desert. What is unique about the Canadian north is that the climate makes the region a frozen desert. A singular fact that has highlighted the extent of the northern drought is that the water level in Great Slave Lake is 20 cm (centimetres) below the normal average. This is a drop of 10 cm from the low water levels recorded in 2014. A full appreciation of the water loss from the lake is gained from knowing that Great Slave Lake is the 10 th largest lake in the world with an area of 27,200 km2 (square kilometres). A 10 cm loss of water depth represents 2.7 billion cubic metres of water, which is about 130 days of average flow in the North Saskatchewan River. The drought however, in not entirely northern in its origin because water levels in Great Slave Lake and, subsequently, the Mackenzie River, are influenced mainly by snowfall and rain in the Peace River basin in northern B.C. and Alberta. The 2015 snowpack was about 50 per cent below normal, and it will likely take several years of above average precipitation for water levels to return to average. In the economic picture, the northern drought is impacting transportation and energy, with the low water levels affecting the barge traffic along the Mackenzie River. Barges provide a lifeline for many communities, facilitating cheap transportation of construction materials and fuel. Last year, the Northern Transportation Company had to cancel some of its barges to northern communities because of low water levels. A shipment of equipment set for Fort Good Hope had to be brought in five months later on the winter road. The energy impact is associated with power generation in the southern NWT. Ninety five percent of electricity in the southern NWT is normally generated by hydro, and 5 percent generated by diesel. Over the past year this ratio has changed to 70 percent hydro and 30 percent diesel, with a cost implication of about $20 million, which would be passed on to the consumers. Fortunately, the Government of the Northwest Territories jumped in with a one-time subsidy to ease the financial burden. From an environmental perspective, the 2014 wildfire season in the Northwest Territories was reputed to be the worst in at least three decades. By early July, there had been over 120 fires reported in the territory, and by mid July the total had reached 160 fires. The smoke generated by the fires combined with a rain storm created some apocalyptic looking conditions in Yellowknife at the end of July, with darkness and coloured lightning. Days later an air quality advisory was issued because of the smoke, as the Air Quality Health Index reached 10 out of 10, 74 | WESTERN CANADA WATER | Fall 2015
Hydro power facility on the Snare River system in the NWT
Smoke in Yellowknife on June 30, 2015
Scenic Yellowknife waterfront without smoke
The smoke was also blown south into the provinces. Environment Canada declared air quality advisories in southern Saskatchewan and Manitoba. Reportedly the smoke reached Bismarck, North Dakota, some 2000 km away. Financially, the wildfires cost a total of $55 million, which was eight times the firefighting budget for the year. Lower water levels in the Yellowknife River, which supplies the City of Yellowknife, contributed in part to the City’s record 32 day boil water advisory that ended in June. The City’s new water treatment facility was fortuitously commissioned in June, bringing the boil water advisory to an end (see article on “Water Treatment on the Rocks” in the Spring Issue of WCW Magazine). While the NWT drought conditions are not on the same scale as California (see article this issue), the impacts are considerable on a number of fronts, and these impacts are being repeated in 2015. CLICK HERE TO RETURN TO TABLE OF CONTENTS
Arviat Nunavut
H
Emergency Water Supply System for Arviat, Nunavut Introduction
Arviat (population 2,318) is located on the western shore of
Hudson Bay in the Kivalliq Region of Nunavut. Arviat is the southernmost community on the Nunavut mainland and is close to the geographical centre of Canada.
Wolf Creek is the seasonal community drinking water sup-
ply for Arviat, and raw water is pumped from the creek into two clay-lined open reservoirs, which provide over winter storage. In the winter of 2010, a leak in the larger of the two reservoirs was detected; however, the cause of the leakage could not be determined because of the ice cover on the reservoir and, therefore, water continued to leak from the reservoir. Given the rate at which water was leaking, and the anticipated water use, it was estimated that there was only sufficient water to last until the middle of May 2011. This would be too early in the season to refill the reservoirs; therefore, an alternate drinking water source was required for the community.
Initially the use of three nearby fresh water sources was evaluated; however, none of these offered a reliable solution. A fourth option was ultimately chosen, which was to use reverse osmosis (RO) to treat sea water from the Hudson’s Bay. The decision to implement a RO system was made in March 2011, which allowed only two months for the system to be designed, procured and constructed before the reservoirs were forecast to be empty. Typically a system of this complexity would take over a year to design, procure and construct.
Design and Procurement of RO System
The design criteria for the treatment system included an operating capacity of 5 L/s, which provided enough water for the hamlet with a 14-hour daily operation of the system. Raw water would be continuously pumped from the Hudson’s Bay and recirculated back to provide freeze protection for the supply line. Raw water was to be filtered prior to the RO system to prevent any particles from damaging the RO membranes, and filtered water
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The Journal of the Northern Territories Water & Waste Association 2013
®
www.densona.com Toronto • Edmonton Denso North America Inc. 90 Ironside Cres., Unit 12, Toronto, ON M1X 1M3 Tel: 416.291.3435 Fax: 416.291.0898
By Nisa Jayathilake, Stantec Consulting Ltd., Edmonton
Arviat Nunavut
was to be stored in a tank upstream of the RO system to ensure consistent flow. Sodium carbonate was to be added for pH adjustment post-RO and to help stabilize the alkalinity of the water, and secondary disinfection was to be achieved through the addition of calcium hypochlorite. Treated water was to be stored in tanks to provide contact time for disinfection and to allow lag time between delivery truck arrivals. RO reject was to be discharged back into the Hudson’s Bay to allow for dilution in the bay. The RO system would be modularized so that it could be could be used in the future for other emergency water supply applications in Nunavut. In discussions with potential suppliers, it was determined that the timeline to design, manufacture and ship a RO unit would take up to 16 weeks, well beyond the time available to the community with the existing water supply. Therefore, a search was completed by contacting suppliers to source available RO units. Two proposals for the supply of an RO system were received and evaluated. It appeared that both proposals were for the same RO system located in storage in Reno, Nevada. Both suppliers proposed to purchase the RO system from a third party and refurbish the system if needed. The available RO system consisted of two skid-mounted trains of RO seawater membranes, and it also included a RO feed pump, PLC control panels, a cartridge pre-filtration system, treated flush system, instrumentation, anti-scalant system and a clean in place system (See Figure 1). The production capacity of
FIGURE 1. Skid mounted reverse osmosis membrane for Arviat.
the available RO system was substantially higher than what was specified (360 L/min versus 262 L/min); therefore, the associated pumping system had to be redesigned to accommodate a higher flow rate.
The supplier intended to first visually inspect the RO system
in Reno in order to identify possible equipment that may need to be refurbished. This would allow time to procure parts while the RO system was shipped from Reno to Canada. After testing, the need for new membranes could be determined.
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15
Arviat Nunavut The unit was prepared for mobilization to another location that would enable future deployment as an emergency water treatment system.
FIGURE 2. Sprung structure for sheltering RO system in Arviat.
Knowing the expected flow rates and rejection rates, associated pumps and chemical feed systems were sized. The increased effluent flow rate altered the required volume for the effluent storage tanks, designed to provide 12 mg/L/min of contact time. Coordination was crucial to the procurement of a temporary structure to house the treatment system, and the building footprint remained in a state of continuing revision as more information on the RO units and process tanks was received; a sprung structure was finally sized and mobilized to Arviat (See Figure 2).
Environmental Considerations
The raw water intake line and screened intake structure were designed to be the maximum practical size in order to decrease the raw water intake velocity, which would reduce the hydrodynamic effects of the intake. The screened intake was located at an elevation high enough above the sea floor to prevent hydrodynamic scouring of the marine sediments by supporting the pumping system with a floating structure. A stainless steel screen was
used on the intake line to prevent entrainment of small-bodied fish or other similar-sized marine biota. The RO reject discharge of the system was designed to minimize the negative impacts of introducing this waste stream into the environment, and a multipart diffuser was used to minimize localized discharge velocities. The diffuser helped to reduce the hydrodynamic impact of the discharge, as well as help to disperse the salt load in the Hudson’s Bay. The salt concentration was not considered to be a significant environmental issue as the percent recovery of the RO system was only 45%; therefore, the salt concentration of the reject was about twice as high as the original seawater.
Delivery and Commissioning
Transportation in and out of Arviat is limited to yearround air transport and seasonal marine transport. With project delivery timeline, a marine delivery of the system was not possible; therefore an airlift would be required. All of the system
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The Journal of the Northern Territories Water & Waste Association 2013
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Arviat Nunavut FIGURE 3. Floating intake for RO system in Arviat.
components were reviewed to ensure conformity to the size and weight limitation of airlift mobilization. A total of seven charters, using a Hercules C130 aircraft, were required to deliver all the material required for the RO system.
Due to reduced consumption rates by the residents
of Arviat and the early seasonal availability of Wolf Creek, the RO system was not required within the original May timeframe. The system was ultimately commissioned onsite in August 2011. The floating raw water pump operated well with changing tides and wave direction (See Figure 3). After commissioning of the system, the unit was prepared for mobilization to another location that would enable future deployment as an emergency water treatment system to other Nunavut communities. S
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The Journal of the Northern Territories Water & Waste Association 2013
17
IPE NSPECTION,
ONDITION
SSESSMENT &
EAK
ETECTION
DAWSON CITY’S SANITARY SEWERS –
assessment and remediation planning Chris Jones, Stantec Dawson City has 1,500 permanent residents and is located in the central Yukon. Once the focal point of the Klondike Gold Rush, the town is steeped in history. This history includes a water and wastewater past that is evident in the wood stave water and sewer pipes still buried beneath some of the streets. The wood stave sanitary sewers were built as early as 1904 and replaced by insulated high-density polyethylene (HDPE) pipes in the late ‘70s (1978). Ground conditions in Dawson City have discontinuous permafrost, and generally consist of organic and silty soils for a major portion of the community. With the discontinuous permafrost, some soils remain frozen year-round, and have ice accumulation in excess of 50% of the soil volume. These variable ground conditions along with the extreme freeze-thaw cycles between the extremely cold winters and warm summers create a harsh environment for buried pipe systems. These conditions cause pipes to
sag, collapse or ovalize, and are exacerbated when ground disturbance occurs during sewer construction, which causes permafrost to melt and the ground to subside. As a result, a considerable number of the sewers constructed in the late ‘70s to replace the wood stave pipe, required replacement in the early ‘90s (1993). After studying the failure mechanisms, the replacement pipe configuration was insulated HDPE with a corrugated metal pipe (CMP) jacket to stiffen the pipe, referred to as Dawson’s own ‘superpipe.’ The scope of the current project was to assess the condition of Dawson City’s sanitary sewers, and develop a long-term remediation capital plan. At the same time, the capacity of the sewer system was assessed, and the condition of other wastewater infrastructure, including the town’s five lift stations, was assessed. The ultimate objective of the assessments was to provide a technical and financial basis for future funding applications.
Closed circuit television (CCTV) videos were used to assess the condition of the sanitary pipes. The CCTV video was an accumulation of almost 20 years of inspections that produced a variety of video quality. Pipe sags were the most prominent issue in the system, with approximately 80% of pipe segments experiencing some degree of sagging. Not surprisingly, pipe sagging was worse in the pipes replaced in 1978, as compared to the ‘superpipe’ replacement work in 1993. Almost 90% of the earlier pipe replacement segments have sags, with 40% considered ‘severe’ with the pipes mostly or completely full of water at all times. The ‘superpipes’ are still prone to sagging with 70% of these pipe segments experiencing sags (but only 14% of these are considered ‘severe’). It is difficult to say whether the lower occurrence of severe sags in the ‘superpipe’ is a result of additional pipe stiffness provided by the CMP, or a result of the pipes being 15 years newer than the 1978 HDPE pipes. However,
“The ultimate objective of the assessments was to provide a technical and financial basis for future funding applications.”
46 | WESTERN CANADA WATER | Winter 2015
CLICK HERE TO RETURN TO TABLE OF CONTENTS
the stiffness of the ‘superpipe’ would certainly be a factor in maintaining the pipe’s integrity with the ground settling that would occur during and after the installation, as the permafrost melted in and around the pipe zone. Other problems noted in the pipe assessments were pipe constrictions caused by pipe collapses, pipe ovality, debris accumulation and service protrusions. Although pipe sags can reduce capacity, the widespread nature of sags creates what may be considered a ‘normal’ operating condition for the Dawson City sewers. On the other hand, pipe constrictions likely pose a larger risk of reduced capacity, and the potential for pipes to become plugged, and are therefore considered a priority for repairs. Complete pipe replacement and local spot repairs were recommended to remediate pipe sags and other problems, as well as to address a few pipes that were found to lack capacity for winter flows. Winter flows are higher than summer flows because of the continuous ‘bleeder’ flows added to the sewer system to prevent pipe freezing during the cold months from November to May. For sagging pipes, there are few options other than to replace the entire pipe segment from manhole to manhole. Local pipe constrictions, such as collapsed pipe or protruding services, may be remediated by local spot repairs. It was recommended that the design work associated with replacing sagged pipe should include additional measures beyond the ‘superpipe’ to reduce the likelihood and severity of the sags. However, pipe sagging may be inevitable here due to the discontinuous permafrost and the soil materials. The cost for sewer pipe replacement work in Dawson City is estimated to be about $11.5 million, based upon a replacement cost of $2350 per metre. The most urgent upgrades are local spot repairs to fix moderate and severe pipe constrictions, replace severely sagged pipes, and upsizing several pipes because of capacity issues. The engineering challenge will be to design these replacements in such a way as to maximize their service life in the challenging ground conditions of Dawson City. CLICK HERE TO RETURN TO TABLE OF CONTENTS
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