United States
Environmental Protection
Agency
United States
Corps of Engineers
Environment
Canada
Environmental Research
Laboratory
Corvallis OR 97330
EPA-600/8-79-027
September 1 979
Research and Development
Cold Climate
Utilities Delivery
Design Manual
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ACKNOWLEDGEMENTS
The creation of this Cold Climate Utilities Delivery Design
Manual took place through the efforts of an eight-member Steering
Committee. The individual members of this Committee represent eight
different groups involved in either design, research or academic efforts
in the North. These groups are based in both Canada and the United
States. The time, material and support of these groups is greatly
acknowledged.
James J. Cameron
Northern Technology Unit
Environmental Protection Service
Environment Canada
Rm. 804, 9942-108th Street
Edmonton, Alberta T5K 2J5
Gary W. Heinke
Department of Civil Engineering
University of Toronto
Toronto, Ontario M5S 1A4
Fred James
Department of Public Works
Government of the Northwest Territories
Yellowknife, Northwest Territories XOE 1HO
Sherwood C. Reed, Co-chairman
U.S. Army Cold Regions Research and
Engineering Laboratory
Box 282
Hanover, New Hampshire 03755
Barry Reid
U.S. Environmental Protection Agency
Corvallis Environmental Research Laboratory
200 S.W. 35th Street
Corvallis, Oregon 97330
William L. Ryan
U.S. Public Health Service
Navajo Area, Indian health Service
P.O. Box G
Window Rock, Arizona 96515
Jonathan W. Seribner
Alaska Department of Environmental Conservation
Pouch 0
Juneau, Alaska 99811
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Daniel W. Smith, Chairman
University of Alberta
Department of Civil Engineering
Edmonton, Alberta T6G 2G7
Dr. Haldor Aamot of USA CREEL was responsible for preparation
of the section on Energy Management. In addition, the U.S. Army Corps
of Engineers District in Anchorage, Ak, contributed to Sections 10 and
14. The assistance provided by R&M Consultants, Inc. is acknowledged
and appreciated.
The technical review and suggestions contributed by R. S.
Sletten and P. Given ^^ ,*,. are acknowledged. The editorial review
provided by Ms. V. Jones, Head, Publications Section (Water),
Environmental Protection Service, Environment Canada, is gratefully
acknowledged by the Steering Committee.
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COLD CLIMATE UTILITIES
DELIVERY DESIGN MANUAL
prepared by
a committee of
Daniel W. Smith, Chairman
University of Alberta
Sherwood Reed, Co-chairman
U.S. Army Cold Regions Research
and Engineering Laboratory
James J. Cameron
Environment Canada
Gary W. Heinke
University of Toronto
Fred James
Government of the
Northwest Territories
Barry Reid
U.S. Environmental
Agency
Protection
William L. Ryan
U.S. Public Health Service
Jon Scribner
Alaska Department of
Environment Conservation
Report No. EPS 3-WP-79-2
March 1979
V
-------
DISCLAIMER
This report has been reviewed by the Corvallis Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for
publication. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
® Minister of Supply and Services Canada 1979
Cat. No. En43-3/79-2
ISBN 0-662-10349-1
N« de Central En43-3/79-2
ISBN 0-662-10349-1
Reproduced by permission of the
Minister of Supply and Services Canada
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FOREWORD
The concept for this manual emerged at the symposium on
'Utilities Delivery in Arctic Regions' organized by Environment Canada in
Edmonton, March 16-18, 1976. The several U.S. and Canadian agencies
responsible for environmental improvement in the north were requested to
assemble a team of experts which would pool its knowledge to create a
'state-of-the-art' design manual on planning and servicing northern
communities. In the ensuing months efforts in both countries resulted in
the creation of a steering committee, and the commitment of staff and
funding to allow this undertaking. Meetings of the committee took place
in Anchorage, Seattle, Yellowknife, and Edmonton. Each member of the
committee was assigned lead responsibility for one or more sections.
The purpose of the manual is to provide guidance and criteria
for the design of utility systems in cold regions to an engineer
experienced in southern municipal engineering practice. He or she may be
working for government, consulting engineers or industry, and would be
involved in the planning, design, construction or operation of utility
services in a northern community or industrial establishment. It is
hoped that this manual will help to improve the level of services provided
and to avoid many of the mistakes made in the past by transferring
'southern engineering' to the North without proper modifications. Often,
a new approach utilizing basic environmental engineering principles
suitable to the north is required.
It is recognized that errors and omissions may have occurred
during the preparation of this manual. The authors would apppreciate
comments and supplemental information which could be incorporated into
revisions of the manual. It is the belief of the authors that this
manual must be updated periodically. Comments and recommendations should
be sent to the:
Northern Technology Unit
Environmental Protection Service
Environment Canada
8th Floor
9942-108 St.
Edmonton, Alberta T5K 2J5
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ii
AVANT-PROPOS
Ce manuel a ete concu a la suite du colloque sur la
"Distribution et 1'Evacuation des eaux dans les regions arctiques",
organise a Edmonton par Environnement Canada les 16, 17 et 18 mars 1976.
On avait invite, lors de cette reunion, les organismes canadiens et
americains responsables de 1'amelioration de 1'environnement dans le
Nord, a former une equipe de specialistes. Ceux-ci devaient mettre leurs
connaissances en commun en vue de creer un manuel de conception a jour,
destine a planifier 1'installation des localites nordiques et les services
essentiels dont elles ont besoin. Par la suite, les deux pays se sont
concertes pour creer un comite directeur et ont affecte les fonds et le
personnel necessaires au bon fonctionnement de 1'entreprise. Le comite
s'est reuni a Anchorage, Seattle, Yellowknife et Edmonton. Chaque membre
s'est vu confier la responsabilite d'une ou de plusieurs sections.
Le manuel se propose de fournir, aux ingenieurs formes aux
techniques courantes dans les municipalites du Sud, des conseils et des
criteres applicables a la conception de reseaux de services pour les
regions du Nord. Ces ingenieurs peuvent etre au service du gouvernement,
d'une firme d'ingenieurs conseil ou d'une Industrie et participer a la
planification, a la conception, a la construction ou a 1'exploitation du
reseau de services d'une localite ou d'une Industrie situees dans le
Nord. II est a esperer que ce manuel aidera ameliorer la qualite des
services et a eviter les erreurs commises dans le passe ou les pratiques
de technogenie applicables aux communautes du Sud etaient raises en
oeuvre, sans modifications prealables, dans les localites du Nord. La
nouvelle facon d'aborder ces questions repose sur les principes
fondamentaux de technogenie environnementale adaptes aux regions
nordiques.
Certaines erreurs ont pu se glisser dans ce manuel lors de sa
preparation. Les auteurs vous sauraient gre de leur faire parvenir vos
commentaires ou des renseignements qui pourraient s'ajouter au texte lors
des revisions periodiques. L'adresse est la suivante:
Sous-section de la technologie nordique
Service de la protection de 1'environnement
Environment Canada
8e etage
9942-1086 rue
Edmonton (Alberta) T5K 2J5
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iii
TABLE OF CONTENTS
Page
FOREWORD i
TABLE OF CONTENTS iii
1 INTRODUCTION 1-1
1.1 Water Supply 1-2
1.2 Water Distribution and Sewage Collection 1-3
1.3 Waste Disposal 1-4
1.4 Solid Waste Management 1-5
1.5 Fire Protection 1-5
1.6 Energy Management 1-6
1.7 Summary and Future Needs 1-6
2 PLANNING AND PRELIMINARY CONSIDERATIONS 2-1
2.1 Objectives 2-1
2.2 Regulations and Legislation 2-6
2.3 Type of Installation or Site 2-9
2.4 Site Considerations 2-9
2.5 Project Management 2-33
2.6 Water Delivery and Waste Collection Systems 2-47
2.7 Operation and Maintenance 2-53
2.8 References 2-57
2.9 Bibliography 2-59
3 WATER SOURCE DEVELOPMENT 3-1
3.1 General 3-1
3.2 Water Sources 3-3
3.3 Water Requirements 3-10
3.4 Structures 3-18
3.5 References 3-31
3.6 Bibliography 3-32
4 WATER TREATMENT 4-1
4.1 General 4-1
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iv
TABLE OF CONTENTS (CONT')
Page
4.2 Process Design 4-1
4.3 Plant Design 4-14
4.4 References 4-17
4.5 Bibliography 4-17
5 WATER STORAGE 5-1
5.1 Purposes and Capacity Requirements 5-1
5.2 Tanks 5-2
5.3 Earth Reservoirs 5-12
5.4 References 5-18
5.5 Bibliography 5-19
6 WATER DISTRIBUTION 6-1
6.1 Introduction 6-1
6.2 General Assumptions and Design Considerations 6-1
6.3 Self-haul Systems 6-3
6.4 Community-wide Haul System 6-5
6.5 Piped Systems 6-17
6.6 Service Lines 6-28
6.7 Materials of Construction 6-35
6.8 Appurtenances 6-40
6.9 Back-up Freeze Protection Mechanisms 6-47
6.10 References 6-49
6,11 Bibliography 6-50
7 WASTEWATER COLLECTION 7-1
7.1 Sources of Wastewater 7-1
7.2 Individual Bucket Systems 7-4
7.3 Vehicle-haul With House Storage Tanks 7-7
7.4 Piped Collection Systems 7-13
7.5 Lift Stations 7-31
7.6 Building Plumbing 7-34
7.7 Typical Construction Costs 7-37
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TABLE OF CONTENTS (cont'd)
Page
7.8 References 7-41
7.9 Bibliography 7-44
8 UTILIDORS 8-1
8.1 Definition and Overview 8-1
8.2 Design 8-4
8.3 Components and Materials 8-11
8.4 Appurtenances 8-15
8.5 Thermal Considerations 8-18
8.6 Maintenance 8-19
8.7 Costs 8-20
8.8 References 8-21
9 WASTEWATER TREATMENT 9-1
9.1 General Considerations 9-1
9.2 Wastewater Characteristics 9-2
9.3 Unit Operations 9-8
9.4 Unit Processes 9-11
9.5 On-site Treatment 9-32
9.6 Operation and Maintenance 9-34
9.7 Costs 9-36
9.8 References 9-39
9.9 Bibliography
10 WASTEWATER DISPOSAL 10-1
10.1 Discharge Standards 10-1
10.2 Subsurface Land Disposal 10-4
10.3 Outfalls '0-9
10.4 Intermittent Discharge '0-12
10.5 Land Disposal 10-15
10.6 Swamp Discharge 10-16
10.7 Sludge Disposal 10-18
10.8 References 10-20
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vi
TABLE OF CONTENTS (cont'd)
Page
11 CENTRAL FACILITIES AND REMOTE CAMPS 11-1
11.1 Introduction 11-1
11.2 Central Facilities 11-2
11.3 Remote Camps 11-30
11.4 References 11-34
12 FIRE PROTECTION 12-1
12.1 General 12-1
12.2 Administration of Fire Prevention Standards 12-1
12.3 Codes and Guidelines 12-2
12.4 Fire Prevention Criteria 12-2
12.5 Equipment 12-3
12.6 Community Fire Alarm Systems 12-8
13 SOLID WASTE MANAGEMENT 13-1
13.1 General 13-1
13.2 Municipal Solid Wastes 13-2
13.3 Industrial and Special Wastes 13-20
13.4 Human Wastes From Households and Establishments 13-21
13.5 References 13-32
14 ENERGY MANAGEMENT 14-1
14.1 Basic Considerations 14-1
14.2 Energy Supply 14-5
14.3 Energy Distribution 14-21
14.4 References 14-43
15 THERMAL CONSIDERATIONS 15-1
15.1 Introduction 15-1
15.2 Freezing of Pipes 15-2
15.3 Heat Loss From Pipes 15-7
15.4 Heat Loss Replacement 15-15
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vii
TABLE OF CONTENTS (cont'd)
Page
15.5 Utility Systems 15-21
15.6 Foundations for Pipelines 15-23
15.7 Materials 15-28
15.8 Buildings and Structures 15-36
15.9 Thermal Calculations 15-38
15.10 Example Problems 15-58
15.11 References 15-72
ACKNOWLEDGEMENTS
SYMBOLS AND ABBREVIATIONS
GLOSSARY
APPENDIX A - PIPE MATERIALS
APPENDIX B - WATER CONSERVATION ALTERNATIVES
APPENDIX C - THERMAL PROPERTIES
APPENDIX D - TRUCKED SYSTEMS
APPENDIX E - VEHICLE SPECIFICATIONS
APPENDIX F - THAWING FROZEN PIPELINES
APPENDIX G - FIRE PROTECTION STANDARDS
APPENDIX H - ENERGY MANAGEMENT DATA
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SECTION 1
INTRODUCTION
Index
Paee
1 INTRODUCTION 1-1
1.1 Water Supply 1-2
1.2 Water Distribution and Sewage Collection 1-3
1.3 Waste Disposal 1-4
1.4 Solid Waste Management 1-5
1.5 Fire Protection 1-5
1.6 Energy Management 1-6
1.7 Summary and Future Needs 1-6
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1-1
1 INTRODUCTION
"Cold climate" in this manual means the climate experienced in
the arctic and subarctic regions of the United States and Canada.* They
include Alaska, the Yukon and Northwest Territories, northern parts of
some of the Canadian provinces and some high altitude areas of the
northern contiguous United States. The special problems of providing
utility services in these regions are addressed in this manual, which may
also be helpful for other cold climate regions, such as the Antarctic,
Greenland, Scandinavia and the U.S.S.R.
A vast, frozen land inhabited by but a few people; that is the
impression most "southerners' have of Alaska, the Yukon and the Northwest
Territories. Much of the evidence supports this impression. About
500,000 people live in Alaska, about 30,000 in the Yukon Territory and
about 45,000 in the Northwest Territories. Disregarding national
boundaries, this vast land stretches over 5,000 kilometres, from Davis
Strait in the east to the Bering Sea in the west. It extends 2,500
kilometres from the northern parts of the Canadian provinces to
uninhabited lands near the North Pole. The recent interest in the energy
and material reserves of the North have made people more aware of these
regions and of the modern communities of sizeable population, such as
Anchorage (200,000), Fairbanks (45,000) and Barrow (3,000) in Alaska, and
Whitehorse (16,000) in the Yukon Territory, and Yellowknife (12,000) and
Frobisher Bay (2,500) in the N.W.T., to name some of the larger ones. In
total there are about 250 communities with populations between 10(J and
1,000 people. Most settlements were established long before the
provision of municipal services was considered important. Their location
and haphazard layout were based on survival and personal preferences.
This has now resulted in high cost for services, which in turn delays the
extension of modern community services to these settlements.
Several factors cause special problems to the development of
services in northern communities. Among them are: permafrost, climate,
remoteness, lack of planning for services, inadequate housing, and often
lack of an economic base. The degree of influence of these factors
* Terms throughout this manual are defined in the glossary.
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1-2
varies considerably over this huge land. Permafrost occurs where the
mean annual ground temperatures are below 0°C for several years. Its
thickness varies with location and can be up to 600 metres. Climatic
variations are great. Minimum and maximum temperatures may average as
low as -50°C and as high as 30°C. Mean annual total precipitation
(rain and snow) varies from about 15 to 45 cm, quite low compared to
southern areas.
The remoteness of most communities results in high transporta-
tion costs. Most of the materials used for services must be imported.
The spread-out, low density layout of existing settlements results in
further high costs. Replanning of a settlement, including relocation of
roads and houses, is, or should be, a prerequisite to construction of
piped water and sewer systems. In some cases, complete relocation of a
settlement may be the most economical solution for servicing the community.
Upgrading existing housing and construction of low and high density
housing for permanent and transient populations are required. Central
commercial, educational and recreational facilities must be incorporated
in the community plan. Any useful and practical plan, be it for housing,
schooling or servicing, must be both technically and economically sound,
and most important, socially acceptable to all groups of the community,
both natives and newcomers.
1.1 Water Supply
All traditional sources of water are present in most parts of
the cold regions but conditions peculiar to these regions require special
consideration of these sources prior to selection of a community water
supply. For example, although there are many lakes, they are generally
quite shallow and many freeze to the bottom, or their effective storage
capacity is severely reduced by thick ice that forms each winter. This
also tends to concentrate minerals in the unfrozen water, which may
render it unsuitable for consumption. Surface water is often highly
coloured from the organic material washed into lakes by runoff. Because
of low precipitation, water contained in lakes may be the result of many
years' accumulation. Attempts to utilize large amounts of this water may
drain the lake and cause loss of supply. During the winter, clean water
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1-3
can be obtained from beneath the ice of rivers, but during breakup,
floating ice and other debris carried by the flood waters are a hazard to
any permanent installation, such as a water intake. Following breakup,
the silt content of the river is extremely high, possibly rendering the
water unusable for several weeks. Small rivers and creeks often freeze
to the bottom, and so their use as a water source may be limited to cer-
tain times of the year. They may also be polluted from waste discharges.
Reservoirs are difficult to construct where the underlying soil has a
high ice content; any attempt to pond water will cause melting of the
underlying permafrost and possible settlement of the dykes.
Groundwater is an excellent source of supply in remote northern
locations. However, in continuous and discontinuous permafrost regions a
reliable groundwater source normally must be obtained from beneath the
frozen zone. This often means expensive wells due to thermal protection
requirements. In addition, the well water may be highly mineralized. In
some locations, ice and snow are melted for water, but the high cost of
fuel or electricity makes this source of water uneconomical if adequate
quantities are to be provided. Water consumption rates show large
variation depending on the method of distribution and the plumbing
facilities. A water supply objective of 50 litres per person per day is
generally considered minimum for adequate drinking, cooking, bathing and
laundering purposes. Only piped systems or a well-equipped trucked
water system can meet this objective. In many communities, houses without
plumbing that are currently served by a trucked water system, only 10 litres
per person per day is supplied and used.
1.2 Water Distribution and Sewage Collection
The dominant characteristic of cold regions utility systems is
the need to prevent both the water and sewage lines from freezing. Heat
may be added to the water or to the mains, and continuous circulation
maintained to prevent freezing. The degree of freeze protection required
depends on whether the pipes are buried or built above ground. Buried
water and sewer lines are preferred for community planning, aesthetic and
engineering reasons. In areas with subarctic climate (arbitrarily
defined as one in which one to three calendar months have mean monthly
temperatures above 10°C), such as Anchorage, Fairbanks, Whitehorse and
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1-4
Yellowknife, underground systems are used. They differ from southern
systems in that various methods of freeze protection are provided, such
as insulation, heating, recirculation and water wasting. Insulation
around pipes also prevents thawing of ice-rich permafrost and consequent
settling of pipes. In the past, underground services were considered to
be not feasible, technically and economically, in ice-rich permafrost
areas. Therefore, above-ground utility systems were constructed in such
areas. They are generally more expensive, cause difficulties with roads
and drainage, are subject to vandalism, and are not desirable from
community planning and aesthetic points of view. Recent engineering
developments may allow underground construction in areas where this was
thought not possible in the past. This will reduce future use of above-
ground utilidors. However, above-ground utility systems will still be
necessary in thermally-sensitive, ice-rich, permafrost areas, or where
excavation equipment is not available for installation and maintenance
or for temporary facilities.
Trucked delivery of water and pickup of sewage is an alternate
means of providing services. Water storage tanks used for homes vary from
an open reused oil drum (180 L) to proper tanks of 1200-litre or more
capacity. In some settlements, water is delivered only to some homes.
Others must pick up water in pails from a number of water points within
the settlement. When the house is equipped with complete indoor plumb-
ing, all wastes are generally discharged to a holding tank, which must
be pumped out several times per week. When indoor plumbing is not avail-
able, toilet facilities may consist of pit privies or chemical toilets
of various designs; however, they usually consist of "honey bags", plas-
tic bags in a container under the toilet. "Honey bags" are picked up
daily or several times per week on a community-wide basis. Wash water
wastes, kitchen sink wastes, and laundry water are usually disposed of
to the ground surface in the immediate vicinity of the home, often contri-
buting to localized drainage and health problems.
1.3 Waste Disposal
Very few communities have sewage treatment plants, although
there are now many package-type plants at industrial facilities in Alaska
which were built as a consequence of the oil discovery and pipeline
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1-5
construction. Sewage lagoons are the most common method for the treat-
ment of wastewater. Few of these meet recommended design and operating
criteria. In the past, they were often constructed by utilizing existing
lakes or low areas with suitable addition of dykes. For most of the year
they provide long-term storage of wastewater, with some anaerobic decom-
position taking place. It is during the summer that extensive biological
activity occurs, with resulting reduction in organic matter. The rela-
tively lower effectiveness of lagoons for wastewater treatment is offset
by their lack of need for skilled and costly operation and maintenance.
In certain subarctic locations, septic tanks and tile fields are used. In
communities near the ocean, disposal of wastewater is often to the sea.
This practice may not be permitted without a special study of local
conditions or some degree of treatment in the future.
1.4 Solid Waste Management
Human feces in "honey bags" are often disposed of without any
treatment in a dump, together with solid waste. In some cases, pits have
been constructed. In other cases, the contents are emptied into a lagoon
which also receives wastewater. Solid waste disposal has, until recent
years, been the most neglected area of sanitation. Where a community
collection system exists, disposal is generally at a dump. Because of
lack of proper cover material, sanitary landfill cannot be practised in
most places. Few dumps are fenced, contributing to widespread and
uncontrolled dumping. In some cases, ill-chosen dump sites contribute to
water pollution. Other forms of refuse disposal, such as incineration,
shredding, baling, etc., have found limited application due to high
maintenance and operational costs.
1.5 Fire Protection
One of the most serious hazards to life and property in remote
northern locations is fire. The seriousness of fire is aggravated by the
problems of providing adequate quantities of water to fight fires during
the extremely cold periods of the year, the extreme dryness of wood and
organic materials, and the dependence on heating systems for survival.
Fire protection techniques must be approached at all levels: the use of
fire retardant materials, development and use of early warning devices,
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1-6
the provision of fire control equipment and personnel, and educational
efforts towards fire prevention.
1.6 Energy Management
Conservation of energy becomes especially important in cold
climate areas. The costs of heating buildings, lighting, hot water, and
operation of appliances are generally much higher than in southern areas.
Heating expenses can be reduced by heavy insulation of buildings and
increased use of waste heat from generating stations. Oil, gas, coal,
wood and hydro-generated electricity are now most commonly used as energy
sources. These may be supplemented by geothermal, solar, and wind energy
where and when feasible.
1.7 Summary and Future Needs
An evaluation of the present level of sanitation in most of the
smaller northern communities shows that the overall situation is more
primitive than in comparably-sized southern communities, but that the
situation is steadily improving. Goals have been set out broadly, for
instance, in the "Proposed Water and Sanitation Policy for Communities in
the N.W.T., 1973". Implementation of these goals will, to a large
extent, depend on available funds.
Development of the northern areas of Canada and of Alaska will
undoubtedly increase in the next few decades, but the scale and pace of
development is still somewhat uncertain. Resource development, including
oil, natural gas, mining, hydro-electric works and transportation
facilities, such as pipelines, roads, railroads, bridges, harbours and
airports, will be built. Several different types of communities will
have to be developed, such as construction and permanent camps, the
expansion and improvement of existing communities, and the building of
new towns. The engineering community must be ready to plan, design,
construct and operate facilities appropriate for the conditions
encountered.
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SECTION 2
PLANNING AND PRELIMINARY CONSIDERATIONS
Index
Page
2 PLANNING AND PRELIMINARY CONSIDERATIONS 2-1
2.1 Objectives 2-1
2.1.1 Health 2-1
2.1.2 Social/economic 2-4
2.2 Regulations and legislation 2-6
2.2.1 Water rights 2-6
2.2.2 Waste discharge permits 2-6
2.2.3 Archaeological clearances 2-7
2.2.4 Environmental assessments or impact statements 2-7
2.2.5 Rights-of-way and easements 2-7
2.2.6 Land use permits 2-8
2.2.7 Safety standards during construction 2-8
2.2.8 Structures in navigable waters 2-8
2.2.9 Safe drinking water regulations 2-8
2.2.10 Clearing houses 2-9
2.3 Type of Installation or Site 2-9
2.4 Site Considerations 2-9
2.4.1 Permafrost 2-9
2.4.2 Location 2-12
2.4.3 Layout 2-20
2.4.4 Energy 2-25
2.4.5 Utilities 2-25
2.4.6 Building design 2-28
2.4.7 Revegetation 2-32
2.5 Project Management 2-33
2.5.1 Construction season 2-33
2.5.2 Transportation 2-36
2.5.3 Equipment 2-42
2.5.4 Labour and inspection 2-43
2.5.5 Type of construction 2-44
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Index (Cont'd)
Page
2.6 Water Delivery and Waste Collection Systems 2-47
2.6.1 Types of systems including construction, operation and
maintenance costs 2-47
2.6.2 Design life 2-52
2.7 Operation and Maintenance 2-53
2.7.1 Community and operator training 2-53
2.7.2 Operation and maintenance manuals 2-55
2.7.3 Reliability 2-56
2.7.4 Management backup 2-56
2.8 References 2-57
2.9 Bibliography 2-59
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List of Figures
Page
Unalakleet, Alaska 2-2
2-2 Ice Stacked to be Melted for Drinking Water
Kotzebue, Alaska 2-2
2-3 "Beaded" Stream 2-10
2-4 Frost Polygon on Alaska's North Slope 2-11
2-5 Ice Wedge 2-11
2-6 Areal Distribution of Permafrost in the Northern
Hemisphere 2-13
2-7 Permafrost in Alaska 2-14
2-8 Distribution of Permafrost and Ground Temperature
Observation Sites in Canada 2-15
2-9 Ice Deposited by Ocean Waves, Unalakleet, Alaska
and Ice Deposited by River, Napaskiak, Alaska 2-18
2-10 Building Damaged Because Ice Around the Piling was
Lifted by Flood Waters, Unalakleet, Alaska 2-19
2-11 Erosion at Bethel, Alaska, Caused by Flooding of River 2-19
2-12 Deteriorated Roads in Bethel, Alaska, Caused by Poor
Drainage 2-21
2-13 Medium Density Apartment Buildings in Godthaab, Greenland 2-23
2-14 Example of Proper Planning 2-26
2-15 Self-refrigerating Thermo-piles in Galena, Alaska 2-27
2-16 Sports Complex in Godthaab, Greenland 2-27
2-17 Open Area Building Construction in the USSR 2-29
2-18 Aerodynamic Building Design to Reduce Snow Drifting
Problems, Prudhoe Bay, Alaska 2-30
2-19 Example of Ice-falling Problems on Building in
Wainwright, Alaska 2-31
2-20 Problems of Summer Construction on Muskeg, St. Mary's,
Alaska 2-34
2-21 Temperature Effects on Worker Productivity 2-34
2-22 Typical Winter Construction Problem, Kotzebue, Alaska
Cat Fell Through Lake Ice 2-35
2-23 Temporary Runway Constructed on Lake Ice, Nondalton, Ak 2-38
2-24 Unloading C-82 Aircraft after Landing on Temporary Ice
Runway 2-38
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List of Figures (con1t)
Figure
2-25 Cost of Living Comparison for Northern Canada 2-40
List of Tables
Table
2-1 Example of Savings with Proper Planning 2-26
2-2 Construction Cost Factors for Alaska 2-41
2-3 Costs of Water Distribution and Sewage Collection
Facilities in Cold Regions (1977) 2-49
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2-1
2 PLANNING AND PRELIMINARY CONSIDERATIONS
It is advisable to apply the principals of good planning to
new developments and to extensions of existing communities. Moving to a
new location or rearranging the present layout according to good planning
practices must be considered because the addition of utilities will
"anchor" a community to a specific location.
Utilities are required and are being installed in many existing
communities whose locations and layouts originated from a subsistence
economy. They were located close to hunting grounds, and near the ocean
or rivers for transportation and fishing. Many of these locations were
also influenced by the RCMP, missionaries, Hudson Bay Company outposts,
and government. Requirements beyond the immediate needs were not consi-
dered; population growth, utilities, housing, and other modern "essentials'
were usually neglected in the community location and layout. Many of the
present villages slowly evolved from a temporary fishing or hunting camp.
For example, nearly all the Eskimo communities along the west coast of
Alaska are located on sand spits projecting into the ocean (see Figure
2-1). These eites suffer from erosion, flooding, lack of room for
expansion, and long distances to a freshwater source. The "old timers"
say that they located there to be near the seal hunting and salmon
fishing, as well as to be where they could see and prepare for the
raiding Indians from the interior of Alaska.
2.1 Objectives
The objectives of planning are to reduce the cost of construc-
tion, and operation and maintenance (O&M) of utility systems, while at
the same time, providing a healthy, functional, convenient, usable,
attractive community or site.
2.1.1 Health
The primary purpose of providing safe drinking water and
sanitary waste disposal is to improve public health (see Figure 2-2).
Protection against water-carried diseases such as intestinal disorders,
hepatitis, typhoid, polio and cysts, to name a few is provided. Also,
the provision sufficient water for personal hygiene, laundry, and
cleaning of the home reduces the occurrence of impetigo and other skin
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2-2
FIGURE 2-1. UNALAKEET, ALASKA.
The bottom of the picture is Norton sound and the
water body in the centre is a salt water tidal slough.
FIGURE 2-2. ICE STACKED TO BE MELTED FOR DRINKING WATER
- KOTZEBUE, ALASKA
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2-3
diseases. A third health consideration is drainage in and near communi-
ties. Swampy or low areas become contaminated, stagnant ponds, which
support mosquitos and other insects which can carry diseases and be a
general nuisance.
Different degrees of overall health improvement are accomplished
with various types of sanitation facilities [1,2,3], The provision of a
safe source of water within a community, but outside the home, will
facilitate health improvement. The improvement is limited, however,
because:
1) It is impractical to have the source near all homes and many
people will continue using the original unsafe source,
particularly if it is closer.
2) Since all water must be hauled, it is used sparingly and
seldom used for personal hygiene, house cleaning, laundry
or other uses than cooking and drinking.
3) Even though safe water is supplied at a watering point, it
often becomes contaminated during transport or storage in
the home.
A considerably greater health improvement can be accomplished
by safely distributing the water to the individual users. Individual
wells are not common in permafrost areas; therefore, the two most common
ways of distributing water are through pipelines and water-hauling
vehicles. Greater quantities of water are made available and the risk of
contamination during delivery is reduced, although the possibility is
greater for hauled delivery than for piped delivery.
In many cold regions, conditions such as deep frost, permafrost,
poor soils and rock may preclude the use of individual outhouses or
septic tank systems. Therefore "organized" community systems are
necessary. In communities where "organized" sewage collection is not
provided, toilet wastes and grey water tend to be disposed of in an
unsanitary and unhealthy manner. Several recent hepatitis outbreaks have
been traced to this problem. A sanitation facility feasibility study
conducted for the towns of Wabasca and Desmarais near Lesser Slave Lake
in northern Alberta, Canada, showed that a completely subsidized hauled
water system would provide the government a return on their investment
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2-4
of at least 62% in one year from health cost savings alone [3,4], The
discomfort and work time missed because of intestinal disorders, etc.,
that would not be reported to the government-operated hospitals and
clinics were not considered.
Cold region communities are usually isolated; therefore, health
problems are usually caused by self-contamination rather than inter-
community contamination. The health risks from discharges of domestic
wastes to the ocean or large rivers can be greatly reduced if outfalls
are designed and constructed to protect shellfish beds and the water
source for the individual site or community. Discharge standards or guide-
lines established for heavily populated areas should not be applied
without considering local conditions. This will avoid the installation
of costly treatment schemes which are designed to provide greater protec-
tion of water uses than necessary, and which are usually far beyond the
ability of small communities to operate and maintain. Pathogens have
longer survival times in cold waters and can be preserved for thousands
of years in the frozen state. Therefore, the potential public health risk
is greater in cold regions. However, the low population density renders
this somewhat irrelevant for some locations, especially coastal areas.
2.1.2 Social/economic
The World Health Organization (WHO) has stressed the importance
of adequate water, sewer, and garbage services to the economic and social
development of a community. There will be poor health in a community
without basic sanitation and there is little prospect of socio-economic
development without good health. Sick or incapacitated people cannot
contribute or participate in the labour market. Moreover, a healthy
person can relocate to a place of employment more readily than a sick or
unhealthy person.
Watering points and central facilities provide a safe community
water supply. However, commercial or industrial buildings, such as
hotels, schools or fish processing plants must be directly connected to
the water source by a pipeline. A sufficient quantity of water cannot be
practically or economically distributed by truck to large industrial or
commercial users. Water and sewer services act as a catalyst to indus-
trial development. The location of government centres, canneries or
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2-5
cold storage plants is often determined by the availability of the
municipal services.
The provision of sanitary conditions is probably the largest
single factor in improving the "standard of living" of a rural area. The
indigenous societies in rural northern Alaska and Canada are changing
from subsistance to cash-oriented economies. The stresses of this
transition are major cause of the high suicide and alcoholism rates in
northern areas. Safe water, adequate sanitary facilities and a healthy
environment will improve productivity and assist in this transition.
The introduction of sanitary facilities in a rural community
often provides the initial contact with such matters as bookkeeping, bill
collection, tax withholding, workmen's compensation and, usually,
unemployment insurance. These along with management and technical
experience, provide a basis for social growth. Proper planning requires
local meetings and decisions, which promote community involvement.
Participation in the development and implementation phases of
the facilities encourages a feeling of community ownership and responsi-
bility. The participation promotes responsible operation and maintenance,
thus increasing the life of the facility. If outside assistance,
especially funding, is needed in a community to provide for the O&M of
the facilities, care should be taken to preserve the community's sense of
self-reliance and avoid further dependance on government assistance. It
is important that outside technical assistance be made available to the
local operators. There are several different philosophies as to what
degree, if any, of the O&M costs of facilities should be subsidized by
the government:
a) A facility should not be constructed unless it is competely
within the community's financial ability to operate, main-
tain, and manage.
b) The entire O&M and management costs should be subsidized by,
or the facilities operated by, the government.
c) The facility O&M costs should be subsidized to the extent of
the savings in health services which are realized by instal-
lation of the facility. In almost all instances involving
indigenous people, 100% of the health services are presently
government-subsidized.
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2-6
There have been instances where well-intended assistance
programs actually contributed to community disorganization. Thorough
examination of the social and economic implications of a project are
necessary to select the type and sophistication of facility that is best
suited for a given community. Legislative, administration, and local
constraints can increase the chance of project failures because they may
limit the types of projects which can be considered.
2.2 Regulations and Legislation
There are many permits or clearances which must be obtained
before construction can proceed. This can be time-consuming, and thus
expensive, and must be budgeted into a project in the beginning. The
major regulations to be followed and clearances to be obtained are listed
below. Requirements differ in individual Canadian provinces and
territories, and the U.S. in several instances. Regulations and
procedures change frequently, and it must be emphasized that one should
check with the applicable agencies before proceeding with a project.
2.2.1 Water rights
In Alaska, the Alaska Department of Natural Resources*
determines water rights and issues water use permits. They also issue
and administer permits for rights-of-way or easements, use of tidelands,
and special land use on State lands. In the Yukon and Northwest
Territories, the Territorial Water Boards conduct public hearings related
to applications for water licenses to ensure that a license applicant
submits sufficient information and studies for the Board to evaluate the
quantitative and qualitative effects of a proposed water use, and sets
water quality standards. Provincial authorities must be consulted for
their regulations and procedures.
2.2.2 Water discharge permits
Waste discharge permits are required for any discharge (solid or
liquid) to surface or groundwaters. Permits are issued by the Alaska
Department of Environmental Conservation**. Further information is
* Division of Land and Water Management, 323 East 4th Avenue, Anchorage,
Alaska 99501.
**Pouch 0, Juneau, Alaska 99811.
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2-7
available from the U. S. Environmental Protection Agency*, which also
administers oil spill prevention and control plans.
Any stream supporting anadromous fish in Alaska must receive
clearance from the Alaska Department of Fish and Game**. Waste dis-
charges in the Territories are regulated by the respective Territorial
Water Boards. Within the provinces, each authority must be consulted.
2.2.3 Archaeological clearances
Archaeological clearances must be obtained if excavation or
construction will take place at any possible archaeological sites. The
Alaska Department of Natural Resources*** administers these clearances
and permits if federal funds are involved. In the Canadian Territories,
archaeological clearances are dealt with under land use permits.
2.2.4 Environmental assessments or impact statements
An environmental assessment or impact statement is necessary in
the U. S. for any federally funded or "major" state or private project
changing the environment, for the better or worse. Which one of the two
is required is usually governed by the degree of the change.
In the U.S., requirements can be obtained from the U.S. Environ-
mental Protection Agency. There were requirements for environmental
assessments or impact statements in the Yukon or N.W.T. at the writing of
this manual.
2.2.5 Rights-of-way and easements
Rights-of-way for construction and O&M must be obtained where
lines will cross private property or other parcels of land not owned by
the constructing agency. They must include a legal description of the
crossing and be obtained from the property owner. They must state
exactly what is allowed, and be legally recorded. In Alaska the U. S.
Department of Interior****, issues rights-of-way across Bureau of Land
Management (BLM) managed lands. In Canada, these are covered under land
use permits.
* Alaska Operations Office, 701 C Street, Anchorage, Ak 99513
** Habitat Protection Section, Subport Bldg., Juneau, Ak 99810
*** Division of Parks, 619 Warehouse Avenue, No. 210, Anchorage Ak 99501
**** Bureau of Land Management,555 Cordova, Anchorage, Ak 99501
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2-8
2.2.6 Land use permits
Land use permits are issued by the Department of Indian and
Northern Affairs. The regulations are not applicable within the
individual communities.
2.2.7 Safety standards during construction
There are many different safety standards. In the United
States, Occupational Health and Safety Authority (O.S.H.A.) standards
usually must be followed. However, there are some government agencies,
such as the U.S. Army Corps of Engineers, which have their own safety
standards and enforce them. Within the State of Alaska, the Department
of Labor* administers safety standards. In Canada these are covered in
the land use permit.
2.2.8 Structures in navigable waters
Permits must be obtained before structures can be placed near or
in navigable waters. In the U.S., two different agencies issue permits
depending on the conditions. They are the U.S. Army Corps of Engineers
and the U.S. Coast Guard. The Corps of Engineers** issues permits for
any activity in navigable waters and wetlands. This is mainly for dredge
and fill operations and for the placement of any structures in navigable
waters. The U.S. Coast Guard*** issues permits for any bridge construc-
tion over navigable waters.
2.2.9 Safe drinking water regulations
In the U.S. the Safe Drinking Water Act stipulates the allowable
concentrations of impurities in drinking water. The act is administered
by the individual state or the U.S. Environmental Protection Agency. It
is discussed in more detail in Section 4 of this manual. In Alaska, the
Alaska Department of Environmental Conservation should be contacted. The
Canadian Drinking Water Standards and Objectives, 1968, are similar to
U.S. regulations. Further information can be obtained from the Federal
Department of National Health and Welfare, Ottawa, and from the
Territorial Governments in Yellowknife and Whitehorse.
* Division of Occupational Safety and Health, P.O. Box 1149, Juneau,
Alaska 99811.
** P.O. Box 7002, Anchorage, Alaska 99501.
*** P.O. Box 3-5000, Juneau, Alaska 99802.
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2-9
2.2.10 Clearing houses
The Alaska State Clearing House* clears projects for compliance
with federal regulations, while the Department of Environmental Conserva-
tion clears projects for compliance with state regulations. The Alaska
Department of Environmental Conservation must review and approve plans
and specifications of all privately and state-funded water supply and
sewerage projects. It also reviews and comments on all federally-funded
projects.
2.3 Type of Installation or Site
Temporary constructions or military camps, resource development
camps, semi-permanent military installations, and new and existing cities
or communities are the types of installations present in cold regions.
The economic base, stability, growth potential and physical permanence of
an installation or community will have very strong influence on the type
of utility system which would best serve that community or site.
Examples of delivery and collection systems are discussed later.
2.4 Site Considerations
2.4.1 Permafrost
Permafrost is not a material; it is the state of any material
which stays below 0°C for two or more years. Solid rock in this
state would not usually create an unusual construction problem. "Beaded"
streams (Figure 2-3) and "frost polygons" (Figure 2-4) are two indicators
of ice-rich permafrost. The frost polygon "lines" are actually ice
wedges, as shown in Figure 2-5. Marginal or "warm" permafrost is much
harder to work with than cold (less than -4°c) permafrost because
small physical disturbances at the surface have a greater thermal effect
on the depth of the active layer. The construction method used in
permafrost will depend on the structure or facility being designed and
the ground stability upon thawing. The ground's stability is determined
by its moisture (ice) content and soil gradation.
Active or passive construction methods have been defined for
application in permafrost areas. Active construction is essentially the
Office of the Governor, Pouch 0, Juneau, Alaska 99811.
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2-10
'
M,
FIGURE 2-3. "BEADED" STREAM
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2-11
,,» ",l*i'"•
'
"«'•&
FIGURE 2-4. FROST POLYGON ON ALASKA'S NORTH SLOPE
FIGURE 2-5. ICE WEDGE
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2-12
prethawing and/or removal of the permafrost or frost-susceptible materials
and their replacement with gravel or some non frost-susceptible material.
Passive construction usually maintains the frozen state of the permafrost
by construction above the ground on piles, use of refrigeration (such as
thermopiles), or insulating the ground surface.
The distribution of permafrost in the Northern Hemisphere is
shown in Figures 2-6, 2-7 and 2-8. Definitions of the extent of the
permafrost at a given location (discontinuous or continuous) are covered
in the glossary.
2.4.2 Location
2.4.2.1 Access. Access is of prime importance when selecting a
location for a new community, camp, or installation. The method, and
thus the cost, of access to a site or community can vary greatly with
remoteness and the factors discussed below.
Because of the importance of air transportation, the site should
provide a suitable location for a runway, considering prevailing winds,
natural obstacles (mountains, etc.) and the availability of construction
materials. Ships or barges are also a major transportation system in the
North, especially for heavy and bulky items. Consideration should be
given to whether a deep, protected harbor is available. If not, could
one be dredged and, if so, would continuous dredging be necessary?
Natural beaches suitable for beaching materials must be available.
Highway and railroad systems are also access considerations in some parts
of the North. Access roads to main highways and main rail lines and
availability of construction materials for them are items which should be
considered if a road system is present or planned.
In most rural or remote locations, snowmachine and dogsled
trails should be considered since they are still important means of
transportation.
New developments such as low pressure tire, off-road vehicles
and air-cushioned vehicles are being tested and may be access considera-
tions in the future. In northern Canada and Asia "cat trains" are used
to deliver materials in the winter. These often travel on frozen river
and lake surfaces. They may be especially useful in delivering
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120
150
180
150
30
120 90 60
FIGURE 2-6. AREAL DISTRIBUTION OF PERMAFROST IN THE NORTHERN HEMISPHERE
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2-14
0 kilometres
b
BARROW
PRUDHOE BAY
Southern limit of
continuous permafrost
Southern limit of
discontinuous permafrost
Mean annual air isotherm (°C)
FIGURE 2-7. PERMAFROST IN ALASKA
-------
Southern kmrt of
continuom parmglrMI
I
I—'
<_n
FIGURE 2-8. DISTRIBUTION OF PERMAFROST AND GROUND TEMPERATURE OBSERVATION SITES IN CANADA
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2-16
materials or equipment for initial construction before permanent access
routes can be developed. Information concerning construction and main-
tenance of ice roads is available from the State of Alaska, Department of
Highways, and the U.S. Army, Cold Regions Research and Engineering
Laboratory (CRREL) [7,8,9],
2.4.2.2 Soil conditions. Another very important consideration in
locating and assessing a site, camp, or community is the local soil
conditions. A complete soils analysis of the site is important and must
include:
1) percent of soil passing and retained on various sieves;
2) accurate in-place moisture or ice contents;
3) penetration rates;
4) shear valves ("vane" shear tests on organic soils, etc.);
5) chloride content and freezing point at different depths;
and,
6) organic content.
Surface vegetation can be helpful in predicting subsurface conditions
[6]. Also, soil conditions can vary considerably over a short distance.
Temperature profiles are extremely important; however, few sites
have instrumentation and temperature records. These should be obtained
as soon as possible. Thermo-couple or thermister strings are usually
used [10], Information has been published on their installation and
monitoring. Temperature information will indicate presence or absence of
permafrost, ground temperatures, and the depth and temperature variation
of the active layer. The changes expected in active layer and ground
temperatures due to disturbances of the surface vegetation cover must be
taken into consideration.
It is usually best to avoid permafrost where possible, by
selecting south slopes in discontinuous permafrost areas, or by selecting
locations near large rivers or lakes which have thawed the permafrost
over time. To lessen the resulting settlement and instability when
permafrost thaws, sites having soils with low or no ice content should be
selected. These are usually well-drained, coarse-grained soils, rather
than fine-grained marshy soils.
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Frost heaving and jacking must be considered in both permafrost
and non-permafrost areas. A frost-susceptible soil has been defined as a
soil having more than 3 percent passing a no. 200 sieve. However,
moisture content also has much to do with frost heaving. Piling must be
imbedded in the ground to a depth sufficient to resist the upward pull
created by the freezing of the active layer. Considerations for frost
jacking and heaving will not be covered in detail in this manual [11,12].
The prevention of seasonal freezing under a structure in a
non-permafrost area would be one method of solving frost heave problems.
The subsurface soil analysis and depth to bedrock, if present, will help
determine the types of foundations possible for a given structure. In
permafrost areas, the possibilities are essentially piling or gravel pads
with the final choice depending on the availability of materials (gravel
and/or piling) and the permafrost temperature. Several studies [13] have
demonstrated reductions in gravel depth are possible with the addition of
layers of plastic foam insulation.
2.4.2.3 Topography. Topography should also be considered when
selecting the best site for an installation, building, camp or community.
The site should be sloping so it will drain (about 1 percent). Natural
obstacles which would promote snow drifting should be avoided. Most
communities in the North are located along rivers, lakes, or the ocean
and flooding is often a problem. Serious consideration must be given to
its frequency and extent, its cause (ice jam, precipitation, etc.) or
whether or not there is current and ice chunks which would cause damage
to surface structures. (See Figures 2-9 and 2-10.) Erosion by rivers or
wave action and/or thermal erosion are sometimes significant (Figure
2-11) and should be considered when selecting a site. South facing
slopes receive more incident sunlight and solar energy, in addition to
providing better protection from colder north winds.
2.4.2.4 Resources. An important item in selecting a location is the
availability of potable water. This will be discussed in detail in
Section 3 (Water Sources). The quality and quantity of water source must
be evaluated, realizing that both will change with the seasons of the
year. Late winter or early spring is the critical time for any surface
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2-18
FIGURE 2-9a. ICE CHUNKS DEPOSITED BY OCEAN
WAVES, UNALAKLEET, ALASK£
FIGURE 2-9b. ICE DEPOSITED
BY RIVER, NAPASKIAK, ALASKA
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2-19
FIGURE 2-10.
BUILDING DAMAGED BECAUSE ICE AROUND THE PILING
WAS LIFTED BY FLOOD WATERS, UNALAKLEET, ALASKA
FIGURE 2-11.
EROSION AT BETHEL, ALASKA, CAUSED BY
FLOODING OF RIVER
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2-20
or shallow groundwater source. Recharge from precipitation through the
surface is essentially non-existent. When ice thickness on lakes and
rivers is at a maximum, most of the impurities that were in the water are
concentrated in the remaining water under the ice. In many cases, it
becomes unfit for domestic use. Water absorbs tannins or lignins from
the mosses and lichens as it seeps through the tundra surface in the
summer [14], Thus, the best quality water is usually obtained in spring
when the melting snow flows over the still frozen ground surface.
Energy sources available locally, such as hydropower, wood,
coal, oil and natural gas, should be considered in selecting a site, as
well as the logistics and cost of importing fuel.
A very important consideration in site selection is the
availability of local construction materials. Probably the most
important materials are sand and gravel.
Almost any structure or facility will need gravel and sand for
foundation pads, backfilling around pipes, making concrete and building
paths, and airstrips. In many communities along Alaska's west and north
coast, gravel is non-existent. In Bethel, for example, barges must go
over a hundred miles upriver to obtain coarse sand, and farther for
gravel. It is sometimes less expensive to barge gravel from Seattle at a
cost of about $26/cubic metre. If bedrock or hardrock outcroppings are
present, they can be blasted for "shot rock" and crushed for fill. Trees
suitable for building logs, lumber and piling can be an important construc-
tion material, and reduce dependence on importing.
2.4.3 Layout
The topography must be considered when laying out facilities.
The slope of the site should be utilized to prevent ponding of water.
Stagnant water becomes polluted and provides mosquito breeding grounds, both
of which can create health problems. Ponding also causes thermal degrada-
tion of permafrost. Snow drifting problems should be avoided in the
location and design of structures. Airports should be located to allow
for future expansion. Most will start with a single strip and develop a
cross-runway as needed. The runway should be oriented with the prevail-
ing winds and above the surrounding terrain to reduce snow drifting.
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2-21
Tank farms should be located away from the community, and water
sources protected from possible oil contamination by diking or some other
means.
Like runways, if the roads are built above the surrounding
terrain they will usually blow free of snow, thus reducing snow removal
efforts and costs. Therefore, cuts should be avoided where possible.
Roads should be constructed up and down the slope where possible. Roads
constructed across the slope inhibit drainage and act as dams. The
backed up water will cause ponding, and saturate and destroy the roadway
subbase and even building foundations uphill from the roads (see Figure
2-12). Culverts placed through roads to prevent ponding will usually
fill with ice at breakup time when they are needed the most. They can be
steam thawed just before breakup but this is expensive and time consuming.
The most satisfactory solution is to eliminate the problem by orienting
the roads up and down the slopes.
\
FIGURE 2-12. DETERIORATED ROADS IN BETHEL, ALASKA,
CAUSED BY POOR DRAINAGE
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2-22
It is not advisable to design layouts with dead end roads.
Because of the need to circulate water mains in cold regions, dead ends
are difficult and expensive to service. Snow removal is also more
difficult. Roads should be designed so there is ample area to place snow
plowed from the road. Docks provided for loading and unloading barges or
ships should be designed to withstand tides, ice movement, spring floods,
and erosion.
The importance of thorough soils analysis was discussed earlier,
but additional borings should be taken throughout the site. The size and
complexity of the utilities or structures to be built and the variations
in the ground conditions will determine the number of soil borings
necessary and the years of record desirable to determine ground•tempera-
tures. More structures have failed because of inappropriate foundation
design, probably due to inadequate soils testing, than for any other
reason. Additional borings should be taken to better define the soils
underlying each building at the site.
Several factors should be considered in locating buildings.
Consideration should be given to moving existing structures to provide
more functional and useful layout. Taller buildings should be located so
they do not "shade" smaller ones from either sun or wind. Where snow
drifting is a potential problem, placement of small structures on the
windward or leeward sides of larger ones must be avoided. One storm
could completely bury a conventional size house located leeward of a
large building or storage tank. The size of snow drifts can also be
reduced by orienting buildings so the long axis is with the wind.
The community layout should be as compact as practicable to
reduce utility construction and O&M costs (see Figure 2-13). Utilidors
with central heating lines can cost $2000 per metre, and buried water and
sewer lines $1000 per metre. Placing unserviced areas and large open
spaces such as parks, school playgrounds, and industrial yards on the
outskirts of a camp or community is recommended.
A typical cost breakdown for a northern utility project
(utilidor extensions in Inuvik, N.W.T.) is 50 percent for construction,
33 percent for materials (on site), and 17 percent for engineering (7
percent for design and 10 percent for inspection).
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2-23
FIGURE 2-13. MEDIUM DENSITY APARTMENT BUILDINGS IN
GODTHAAB, GREENLAND
An evaluation of existing communities in the Northwest
Territories provided the following approximate figures for the length of
water and sewer lines required:
Community Population
Length of water line plus sewer
line per capita* (metres)
Less than 300
300 to 600
600 to 1000
1000 to 2500
Greater than 2500
8
7
6
4.5
3.5
* These figures are based on five persons per residence and do not
include service lines. They are also based on utilidor systems or
systems with the water and sewer lines in the same trench.
Alaskan experience differs somewhat. The systems installed
are usually buried pipes with water and sewer lines in separate trenches.
The figures above should be increased 1.5 times for Alaskan communities.
Seventy-five percent of the above pipe lengths was water and
sewer together, 15 percent was sewer line only and 10 percent was water
line only. These figures should be used for rough estimates only. Actual
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2-24
conditions will make adjustments necessary, for instance, for a community
that is spread out along a river. A community of 200 persons could be
estimated to have 1600 m of water and sewer lines. One thousand
two-hundred metres would be water and sewer together (600 m of water and
600 m of sewer), 160 m would be water line only and 240 m would be sewer
line only.
For a well laid out site, the following lengths of pipe per
capita are provided as a guide:
Single family subdivision 3 to 4 m/capita
Multi-family area 0.2 to 2 m/capita
Apartment area 0.02 to 1 m/capita
A compact layout may make a central heating plant practical,
and this can reduce heating costs by reducing energy consumption. The
risk of fire, which is a major cause of accidental deaths in cold
regions, is also reduced. Most home fires are caused, directly or
indirectly, by heating stoves and a central plant will eliminate the need
for these. The main disadvantage of central heating is the difficulty
of expanding the core system when the community or camp unexpectedly
expands. Heat is also lost during transmission. Heat loss is much
higher with above-ground distribution.
Service lines are the source of most water distribution and
sewage collection line freezing problems. Buildings should be located
as close to the utility lines as possible to minimize service line
lengths. If the water and sewer lines are to be placed in the street or
alley rights-of-way, the buildings should be placed on the lot within
18 m of the lines, if possible.
There are advantages to placing the main lines along rear lot
lines in a right-of-way. The snow is usually not removed, as it would be
in the street, providing warmer ground temperatures. In non-permafrost
areas the frost penetration is usually significantly greater under snow
cleared or packed areas. They are also not as likely to be damaged by
vehicles. Service lines to both rows of houses are shorter because the
rights-of-way for alleys or utilities do not need to be as wide as the
streets in front of the lots, and houses can be placed close to service
lines since "back yards" are not used very much in northern communities,
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2-25
especially in the winter. Manholes, lift stations and valve-boxes can be
terminated above-grade, making maintenance easier. Also, with above-
ground utilities the service connection will not require a road crossing.
Figure 2-14 and Table 2-1 show an example of the savings
possible when the layout of a community is properly planned.
2.4.4 Energy
Energy is expensive and requirements are high; therefore,
facilities must be designed to conserve energy. One example is to install
heat exchangers on the cooling water jacket and exhaust stack of power
plants, which can more than double the total energy extracted from fuel
oil. Usually only 30% of the fuel energy is used. The cold temperatures
can also be used as a resource. Examples of this are self-refrigerating
thermo-piles (Figure 2-15), desalinization using the freezing processes,
and ice roads.
2.4.5 Utilities
Utility systems must serve the "total" community. For example,
it is not economical to have several small generators serving separate
buildings or complexes when one larger unit could serve the entire
community.
In planning communities or camps, it is important to provide
recreation facilities which can be used during the long, dark, cold winters
(Figure 2-16). These facilities reduce the social and psychological
problems ("cabin fever") prevalent in isolated, cold regions. Communities
or camps should have large buildings such as gymnasiums and arenas that
can be used for basketball, volleyball, curling, hockey, and other popu-
lar indoor games. Swimming pools can also be a very worthwhile addition.
Very few of the indigenous people have learned to swim, even though they
continuously use the ocean and rivers for transportation, because of the
low water temperatures, even during the summer. Swimming pools could
remedy this in addition to providing exercise and recreation during the
winter. A useful side benefit to having a swimming pool in a school or
recreation complex is that it can double as a fire protection reservoir,
which is usually an important but expensive addition to buildings in cold
regions.
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2-26
Water
Highway
Road crossing
over utilidor
Utilidor
-. r Water
Original development proposal
Improved development proposal
FIGURE 2-14. EXAMPLE OF PROPER PLANNING
TABLE 2-1. EXAMPLE OF SAVINGS WITH PROPER PLANNING
ITEM ORIGINAL IMPROVED DIFFERENCE
MGn8oh ^ , N 1936 1887 49
New Roads (m)
Utilidor 191? 1646 2?1
Length (m;
Road 10 6 4
Crossings
Water System A ? ?
Loops
Approximate uo 152 ^
Lots
Junctions ~ 1 1 1
& Bends
TOTAL
NET SAVINGS
(1973 DOLLARS)
3,000
109,000
40,000
2,000
84,000
2,000
$240,000
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2-27
FIGURE 2-15. SELF-REFRIGERATING THERMO-PILES IN
GALENA, ALASKA
FIGURE 2-16. SPORTS COMPLEX IN GODTHAAB, GREENLAND
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2-28
Most communities and camps in cold regions are remote with only
intermittent service, even by air, from larger population centres.
Therefore, it is very important to provide complete standby for all
essential components of any utility. Alarms and safeguards, such as low
water temperature alarms, low flow alarms, and low or high voltage
alarms must be provided to warn operators of any pending problems. The
importance of a reliable, knowledgeable operator will be discussed later.
Longer lead times must be allowed when requesting utility
services. Requests for electrical service to a project site must be made
to the local electric utility. In most remote Alaskan communities this
is the Alaska Village Electric Corporation. In the Northwest and Yukon
Territories, it is usually the Northern Canada Power Commission.
When constructing a building or facility requiring water and
sewer service, notice should be given well ahead of when the service is
needed. It may be necessary to expand the source or storage, which could
mean bringing materials in on the one and only barge per year.
2.4.6 Building design
Buildings should be designed for multiple use wherever possible.
It is expensive to heat and maintain a building continuously when it is
only used a few days each week (such as a church) or part of the day
(such as a school). Medium height cubical buildings should be used
rather than low and spread out types. They are more efficient from a
heat loss standpoint and provide a more compact arrangement for utility
service. There is somewhat more danger in case of fire, but fire
protection must be designed into any building. Open areas with plants
are important from an exercise and psychological point of view, and have
been provided in large buildings in the USSR (Figure 2-17) and Prudhoe
Bay, Alaska.
Windows are necessary but they are a high heat loss and main-
tenance item and should be designed to provide the most benefit with the
smallest area. Window orientation toward the south, multiple glazing,
and wood casings maximize insulation and energy savings. Windows extend-
ing above or below eye level should be avoided but it is important to be
able to see out sitting or standing. Windows are of no value during
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2-29
FIGURE 2-17. OPEN AREA BUILDING CONSTRUCTION IN THE USSR
darkness, therefore, insulated shutters should be provided to reduce heat
loss.
Buildings should be well-insulated to minimize the total annual
cost of heat and amortization of the insulation costs. (See Section 14).
Vapor barriers are also a very important part of any building in cold
regions. Information is available concerning vapor barriers and types of
insulation suitable for different applications [15,18], Insulation must
be kept dry. Absorption of 8 percent moisture (by volume) will reduce
the insulating value by one-half. An impermeable or low water absorption
insulation should be used in damp or wet locations. The reduction of air
exchange is as important as insulation in reducing building heat losses.
Some air exchange in a room or building is necessary. Quantities vary
with use and are usually stipulated in building codes, but anything over
these minimums should be avoided.
In areas where snow drifting is a problem, aerodynamic design of
the building exterior can reduce drift size, and also move the drifts
which do build up further from the building [16] (Figure 2-18).
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2-30
Permafrost table
Top of tundra
Steel roof truss
Stud bearing walls
Plywood & joist floor
Concrete slabs
/I Steel beam
Steel skid
Concrete pile caps
• Steel piles .'• •
' . 30' below grade
Transverse Section through Composite Building
r
f\. Rectangular-section building
B. Rectangular-section building with
leading edge rounded to a half cylinder
C. Final building form
FIGURE 2-18. AERODYNAMIC BUILDING DESIGN TO REDUCE SNOW DRIFTING
PROBLEMS, PRUDHOE BAY, ALASKA.
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2-31
Building entrances should not be placed in the windward or
leeward sides of buildings. If possible, all doors should be double
doors with a space between them large enough so one is closed before the
second one is opened. This will greatly reduce the air exchange when
going in or out of the building. All doors and entrances must be
protected from snow and ice falling from the roof (see Figure 2-19).
Serious accidents have been caused by ice falling on someone leaving a
building when a door is slammed.
Roofs probably cause more problems than all other building
components combined in cold regions. Hip roofs should be used if
possible, with flat roofs being the last choice. It is very important
that all roofs be well insulated and provided with a very tight vapor
barrier [17].
Building heating systems must be as fool-proof as possible with
standby pumps and boilers provided for emergencies. Hot water circulat-
ing systems in remote, cold region areas should be charged with a glycol
FIGURE 2-19.
EXAMPLE OF ICE-FALLING PROBLEMS ON
BUILDING IN WAINWRIGHT, ALASKA
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2-32
solution, but this must be taken into account in the sizing of boilers,
pumps, expansion tanks and other system components [18].
Humidity is an important consideration in cold regions, especially
inland. Humidity drops extremely low with cold winter weather. For
comfort, as well as to prevent damage to furniture, the humidity should
be kept at about 30 percent by using humidifiers. High humidity (above
50 percent, depending on temperature) can cause equally as numerous and
serious problems due to condensation on windows, walls and in insulation.
During warm spells or in the spring this frozen condensate can ruin
paint, insulation, and even destroy the building by inducing wood rot.
In very humid areas, such as pumphouses or sewage lift stations, moisture
control or dehumidifiers are necessary.
Building foundations will not be covered in this manual but
information is available elsewhere to help the designer with this most
crucial component of building design in cold regions [19,20,21],
2.4.7 Revegetation
Revegetation will usually be required where the natural
vegetation has been damaged or removed by construction. It is necessary
to prevent erosion and make the site more aesthetically pleasing. The
purpose of seeded plants is primarily to provide some growth to protect
the soil until the natural vegetation returns. The U.S. Soil Conserva-
tion Service and the Alaska State Division of Aviation have developed the
following recommendations for seeding tundra areas [22]. The best time
for seeding is before mid-summer and after break-up. However, scattered
seeding has been successful even when the seeds were broadcast on the
snow in the spring. The grasses will probably die out in four to five
years but the natural vegetation should be well on its way to recovery by
then.
Recommended seed rates are:
1) Meadow Foxtail (common) = 22.4 kg/ha
2) Hard Fescue (Durar) =22.4 kg/ha
3) Red Fescue (Arctared) = 33.6 kg/ha
4) Annual Ryegrass (Loliun Multiflorum) = 33.6 kg/ha
TOTAL = 112 kg/ha
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The mixture should be seeded, and fertilized immediately and at
the beginning of the second year with the following fertilizers and
rates:
1) 10-20-10 - 448 kg/ha,
2) 33-0-0 - 112 kg/ha.
2.5 Project Management
Project management is an extremely important part of planning
for remote, cold regions installations.
2.5.1 Construction season
The length of the construction season varies with factors such
as soil conditions, length of daylight, and climate. However, construc-
tion cannot start in any location until the materials and equipment are
on-site. Barges normally arrive in Barrow, Alaska and the Eastern Arctic
around the first of September, which is near the end of the construction
season. This means that materials must be shipped one year in advance
for construction to start the following summer. The length of the normal
construction season varies from two to three months along the Arctic
coast, to six or eight months in more southern areas.
Some soils, such as low moisture contents sandy-gravelly soils,
can usually be excavated more easily when frozen. When they are thawed,
shoring is necessary to prevent the trenches from caving in. Some muskeg
or highly organic soils are also easier to excavate in the frozen
condition (see Figure 2-20). When thawed, such soils often will not
support equipment or even people. On the other hand, saturated gravelly
silts are nearly impossible to dig when frozen and must usually be either
thawed or blasted.
The weather (temperature, wind, snow, rain, etc.) greatly
affects the amount of work accomplished during a constrution period.
Studies have indicated that temperature affects workers and equipment as
shown in Figure 2-21 when other environmental factors are considered
ideal. Darkness, wind and rain will reduce productivity further. The
effects of cold temperatures on oils, diesels, antifreeze solutions,
steels, woods, and plastics are shown in Appendix A. It is important
that these be understood before cold temperature construction is attempted,
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2-34
FIGURE 2-20.
PROBLEMS OF SUMMER CONSTRUCTION ON
MUSKEG, ST. MARY'S, ALASKA.
100
o
0)
'o
c
0>
a
Q)
0.
-40
FIGURE 2-21. TEMPERATURE EFFECTS ON WORKER PRODUCTIVITY
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2-35
The lack of light can be partially corrected by using artificial
light. A chart showing the hours of daylight at various latitudes is
included in Appendix H. Daylight values will be shortened, of course, in
a location having mountains or other local terrain variations.
More and more contractors in cold regions are attempting winter
construction of buildings to stretch out the construction season and take
advantage of lower transportation and equipment costs with cheaper and
more available labour. Concrete work must be kept warm and aggregates
must be kept from freezing or thawed before use. Excavation should
usually be done before the ground freezes. (See Figure 2-22).
FIGURE 2-22. TYPICAL WINTER CONSTRUCTION PROBLEM,
KOTZEBUE, ALASKA
Winter construction can create severe moisture problems in
buildings. Portable heaters used to keep the interior warm produce
considerable amounts of water in the combustion process and, unless they
are vented to the outside, this water accumulates in the building
interior where it can cause problems for years to come.
The decision must be made as to whether to work longer hours and
pay overtime, or extend construction into the winter and/or another
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2-36
construction season. This is an economic consideration which may depend
on weather, overhead costs, and other local conditions. Also, studies
have shown that working overtime for an extended period of time is not
cost effective.
2.5.2 Transportation
2.5.2.1 Methods of shipping. Construction materials and equipment are
delivered to many construction sites by barge or ship. It is very
important to investigate the following items to avoid delays in project
construction.
1) The number of sailings per year and the chances of
nondelivery due to shore ice not moving out, rivers being
too low, or other natural factors should be known.
2) Delivery schedules should be determined so that materials
and equipment can be at dockside at the point of disembark-
ment. There is usually a specific and limited period of
time during which materials will be accepted.
3) The rates charged and the criterion that they are based on
(volume or weight) should be checked. There often are
demurrage charges on shipping company containers. Rates for
barge transportation have steadily increased over the past
few years. There is also a daily charge for non-scheduled
stops (communities not normally on the route).
4) On many scheduled barges space must be reserved in
advance. It is important to check the capacity of barges
serving the area and the capacity of off-loading docks and
equipment before ordering materials and equipment.
5) Chartering barges should also be considered. The
economics of chartering will depend on the amount of
materials to be shipped and whether the location is a
scheduled stop on an established route.
6) The facilities available for off-loading at the site
should be determined. If there are no docks, are there
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2-37
suitable beaches for beaching the barge? What equipment
(such as cranes, trucks, cats, etc.) is available? Can the
barge or ship be brought into shore or must landing barges
be used to shuttle materials between the ship and shore?
Ship or barge landings or docking must usually be
coordinated with the tide.
Air transportation is becoming more and more competitive in
cold regions and is the only transportation method to some sites in the
Arctic and Antarctic. The following should be investigated:
1) The landing strip capabilities should be determined. Is
the strip useful year-round or just in the winter? Even
year-round strips usually have seasonal limitations, such as
soft spots in the spring and cross-wind limitations, depend-
ing on the aircraft. Temporary strips can be constructed on
lakes or river ice or on compacted snow during the winter
[9] (Figures 2-23 and 2-24). Lake ice is usually smoother
than river ice and is thus suited for a wider range of
aircraft and heavier loads. Equipment must be available
locally or brought in to construct ice or snow landing
strips. Some other items which must be considered are:
runway length, approaches, type of surface, navigational
aids, runway lights, and elevation.
2) A check should be made into the available aircraft and
their capabilities. Size limitations, which are usually
defined by the size of the loading door and cargo space, and
weight limitations must be determined for the different
sizes and kinds of planes. The costs (both flying time and
standby time) are needed, along with the performance
limitations for each plane. Some planes require special
fittings for use on gravel strips. What type of facilities
for loading and unloading are available at the site? The
available facilities should be compared with the
requirements of the aircraft.
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2-38
FIGURE 2-23. TEMPORARY RUNWAY CONSTRUCTED ON LAKE ICE,
NONDALTON, ALASKA
FIGURE 2-23. UNLOADING C-119 AIRCRAFT AFTER
LANDING ON TEMPORARY ICE RUNWAY
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2-39
Similar considerations are necessary in areas served by roads
and/or railroads. Are the roads useful year-round or are they seasonal,
and do they carry load restrictions during the spring? Rates by the
weight or volume and the size and weight restrictions must be considered.
A check on demurrage charges on railcars or containers should be made.
2.5.2.2 Transportation costs. When comparing the benefits and costs
of the different methods of transportation available, consider:
1) the gain in construction time achieved by using air
transportation;
2) the number of times the materials and equipment must be
handled (the amount of shipping damage is directly related
to the number of loadings or off-loadings needed);
3) the true shipping costs (i.e., including demurrage cost,
lighterage costs and long-shoring);
4) the difference in costs for chartering vs. using scheduled
carriers for any alternative.
Cost adjustment indexes have been developed for the cold
regions of North America. Figure 2-25 shows a Canadian cost of living
index with an index of 1.0 based on construction in the Great Lakes area
[23]. Table 2-2 indicates construction cost factors for Alaska for the
construction of repetitive type facilities, such as buildings, with an
index of 1.0 assigned to Washington, D.C.
The Alaskan and Canadian cost indexes cannot be directly
compared because the Alaskan index is for straight construction costs
while the Canadian index is only a "cost of living" comparison between
different points in northern Canada.
2.5.2.3 Shipping considerations. Because of harsh environment, the
shipper's or carrier's liability for loss and damage of the shipment must
be investigated. Loss or damage of one important component could delay
completion of the project for one year or more. Materials and equipment
must be packed to prevent damage during shipment. Crating and protection
needed during transit must be specified. Items usually must be handled
several times. Also, they may be vulnerable to salt water while on barges.
-------
Level of
suggested Xtowince
NJ
FIGURE 2-25. COST OF LIVING COMPARISON FOR NORTHERN CANADA
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2-41
TABLE 2-2. CONSTRUCTION COST FACTORS FOR ALASKA
NOTE: The following location factors are applicable to the construction
of repetitive type facilities, such as dormitories, dining halls, BOQ's,
administrative buildings, fire stations, warehouses etc., which make
maximum use of local skills, materials, methods and equipment. They are
not applicable to more complex facilities.
The location factors are multiples of the basic value of 1.0
assigned to Washington, D.C.
Taken from U.S. Air Force Publication 83-008-1, Dated 3/1/62
LOCATION
FACTOR
Aleutian Islands
Adak
Attu
Cold Bay
Dutch Harbor
Shemya
Anchorage
Barter Is., North Coastal Area
Bethel
Clear
Coastal Area, North of Aleutians
Eielson AFB
Elmendorf AFB
Fairbanks
Fort Greely (Big Delta)
Fort Yukon
Inland Area, North of Aleutians
Juneau
Kanakanak
Kenai Peninsula
Kodiak
Kotzebue
Naknek
Nome
Northway, Highway Area
Point Barrow
Tanana
Whittier
Seattle
Galena*
3.0
3.0
3.0
3.0
2.5
3.1
1.7
5.2
3.8
1.7
3.5
1.9
1.7
1.9
2.2
2.6
4.0
1.8
2.1
2.1
2.5
3.0
2.1
2.3
2.3
4.6
3.2
1.9
1.0
3.0
* Building cost (heated)
50 000 ft2.
$150/ft2 with 3 stories and
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2-42
Items such as foam insulation components, paints, polyelectrolytes,
adhesives and other materials must not be allowed to freeze.
2.5.3 Equipment
The type of equipment purchased and the careful preparation of
equipment for cold weather work are very important time and money savers.
Equipment must be in top shape before it is sent to a remote
location. Equipment and tools for repair are usually limited in remote
areas, and importing mechanics and parts is expensive in addition to the
cost of "down time". A large inventory of critical spare parts is
recommended and standardization of equipment to reduce the parts
inventory will prove economical. Standby units should be provided for
critical equipment so the job is not stopped completely.
Equipment should be planned carefully before the initial ship-
ments to the job site, especially large pieces that cannot be flown in at
a later date. For mobility, select equipment that can be flown from one
location to another in the available aircraft. Equipment selection for
the conditions that will be encountered, such as heavy-duty rock buckets
for digging frozen ground, and grousers on backhoes, is important.
However, equipment selected should not be too highly specialized in order
to reduce the number of pieces needed. Preventative maintenance is
extremely important. Schedules should be established and adhered to.
Good maintenance records are important as they will:
1) provide back-up data when the time comes to decide which
brand of equipment to select for future projects,
2) help pinpoint weaknesses and reduce the spare parts
inventory,
3) provide checks to ensure that preventative maintenance is
being performed on schedule.
The initial cost of a piece of equipment is usually not as
important as its reliability. Equipment should be selected for which
there are reliable dealers with adequate parts inventories, service
facilities and staff nearby.
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2.5.4 Labour and inspection
Labour costs are presently escalating at a higher rate than
material costs and now attribute to 50% of a project's total expenses.
Studies and experience indicate that it is better to use local labour
whenever practical.
There are several reasons for this:
1) Local people are more familiar with, and adapted to,
local conditions, including weather.
2) If they live near the project site, camp facilities will not
be required.
3) If they live in the community receiving the facilities they
have more at stake because they have to live with the final
facilities. Knowledge gained during the installation will
also facilitate repairs.
4) Local hiring provides an economic boost to the area in
addition to the benefits provided by the project.
5) Local people can be trained as equipment operators,
carpenters, and plumbers, which will help them obtain jobs
in the future. Productivity of these trainees is usually
lower than experienced labour.
There are some special problems which must be kept in mind:
1) In some locations there are not enough skilled and
reliable workers.
2) Local customs and politics must be recognized and honoured.
3) Supervisors and specialists will probably still have to be
imported. They must be selected carefully, and they must be
able to work and communicate with the local people. They
must also be willing to tolerate the remote conditions.
This hardship is usually offset by high wages.
4) Union contracts may preclude using non-union local labour.
Safety precautions are very important in cold, remote locations
because of the distance to hospital facilities and the harshness of the
weather conditions. In cold weather, workers should use the "buddy
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2-44
system" whether working or traveling. This way there is always someone
to help in case of an accident. Inspection methods and frequency are
extremely important. A small mistake, or a case of poor workmanship can
cause an entire facility to fail. Once equipment is removed it is very
expensive to return it to repair mistakes. Thorough inspection is even
more critical when the contractor is from the south and not familiar with
the problems of cold regions. Inspectors should keep in mind the
following items:
1) All irregularities or possible problem areas in the field
should be documented immediately. Polaroid (or equal)
photographs will enable the inspector to mark discrepancies
immediately on the photograph, and he can see that he has a
good picture at the time he takes it. Also, thorough daily
written reports and verbal communications with the
supervisor and/or contract officer are extremely important.
2) Changes from the original design must be recorded accurately,
and as-built drawings of the project prepared.
3) The contract documents must be thoroughly understood, and
who has authority to make changes. It is important that the
inspector does not permit changes in the field that he is
not authorized to make.
4) Regular contact with the project engineer and contracting
officer must be maintained. They should be well-informed as
to problems and progress of the project.
5) Accurate measurements of actual quantities of material used
must usually be made for payment purposes. Most of the
above duties must also be performed by the on-site supervisor
of force account jobs who, in addition, must keep equipment
maintenance records and coordinate all labour on the
project.
2.5.5 Type of construction
The two most frequent methods of construction are contract and
force account. There can also be a combination of the two on the same
project.
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2-45
2.5.5.1 Force account. Force account construction is where the funding
source hires its own crews, purchases its own materials and equipment,
and accomplishes the construction.
The following are some of the advantages of force account
construction:
1) It tends to utilize local labour or contractors to a
greater extent.
2) It is usually lower in cost.
3) Training of the operators and users can take place during
construction.
4) Equipment used during construction can more easily be left
at the site for operation and maintenance of the completed
facility.
5) It is easier (and less expensive) to phase a project or make
major changes during construction should unforeseen
difficulties arise.
6) Shorter lead times are usually possible for materials and
equipment ordering. (Contracts have to be advertised,
awarded, etc., and the successful bidder still must purchase
his materials.)
7) There is more flexibility to fit into the local environment
and social conditions.
2.5.5.2 Contract construction. Contract construction is where the
funding agency supplies plans and specifications and contracts with a
private firm to accomplish the construction. Advantages of this
contracting method are as follows:
1) There is usually more control on the job, and inspection
is usually more thorough.
2) Completion times are sometimes shorter because they are
specified in the contract.
3) The owner or funding agency does not take as high a risk and
also does not need as large a work force on-site (inspectors
only).
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2-46
Some jobs will combined force account and contract. For
instance, there are usually parts of a job for which the owner does not
have qualified crews to perform and he must contract those portions.
Large welded (on-site) steel storage tanks, erection of prefab metal
buildings, construction of sewage treatment plants, electrical work,
control and alarm systems and installation of piling are examples of
these specialities.
2.5.5.3 Construction techniques. There are three main construction
techniques: "stick built", "prefab", and "modular". In stick built
construction the materials are shipped to the site, and all cutting and
fabricating is done on-site. Prefab construction is where parts of a
structure, etc., are prefabricated at the point of manufacture and
assembled at the site. Modular construction means large components are
constructed at the point of manufacture and shipped to the site already
constructed.
Each technique can be useful under different circumstances.
Modular construction has a definite advantage when there is a short
construction season, a labour shortage, or labour is expensive at the
site. Shipping limitations may dictate stick built or possibly prefab
rather than modular construction. Modular construction may allow the
facility to be placed in operation with most of the defects worked out at
the point of manufacture, but field changes to fit varying site
conditions are more difficult and expensive to make.
2.5.5.4 Above or below-ground. The decision whether to place utilities
above or below-ground must be made. The major engineering consideration
is the soil conditions at the site. Poor soil conditions (see Section
2.4.1) and lack of non-frost susceptible backfill will usually force
construction above-ground. Otherwise below-ground installation is
preferable. Important considerations are:
1) Above-ground lines are subject to vandalism and traffic
damage.
2) The allowable heat losses and the cost of energy (heat)
required for above-ground lines must be assessed.
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2-47
3) The necessity of holding grades with above-ground gravity
flow pipelines will greatly increase the cost.
4) Below-ground systems are less expensive to install because
they eliminate the need for piles and road and sidewalk
crossings.
5) Below-ground systems allow for more normal town planning and
do not artificially dissect the community.
6) More expensive equipment is necessary to maintain
below-ground lines.
Heat loss is directly proportional to the difference between
the inside and outside temperatures. An above-ground utilidor or
pipeline will have about three times the heat loss of a similiar line
buried just below the surface.
If lines are buried, the depth of bury should be carefully
determined. This will be covered in detail in Section 14. Heat losses
from buried lines are considerably less but excavating frozen ground to
find and repair a leak, etc., can be difficult. Also, a pipeline leak
can travel under the frozen surface layer and surface through a ground
tension crack several feet away.
2.6 Water Delivery and Waste Collection Systems
2.6.1 Types of systems including construction, operation, and
maintenance costs
The major types of water delivery and waste collection systems
used in cold regions are discussed in the following paragraphs. There are
many variations and alterations which can be made to the basic types
presented here. Detailed descriptions and design information will be
presented in later sections of this manual.
Consideration should be given to phasing facilities. The first
phase could be a central watering point, with a piped or hauled system
following a few years later. This would lessen the economic and cultural
shock to the community of the immediate installation of a complete
system.
Initial construction or installation costs are presented for the
different types of systems. They are based on 1977 construction costs
-------
2-48
and should be considered rough estimates only. Actual costs can vary
considerably, depending on the sophistication of the facility, the degree
of water and sewage treatment necessary, foundation problems and other
factors.
Operation and maintenance (O&M) costs are also presented for the
different types of sanitation facilities. For most facilities, labour
costs are by far the most significant part of the O&M budget. A military
site could be an exception because labour is covered under "general
overhead".
Two other large O&M costs are oil and electricity. Both of
these items are largely dependent on the delivered cost of oil. If no
surface transportation is available it is necessary to fly in oil. A
complicated water or sewer treatment process will make the cost of
chemicals and their transportation a major O&M item. The approximate O&M
costs presented for each type of facility do not include amortization of
the initial construction costs. They do include funds to replace
short-lived components such as boilers, pumps, and vehicles (items with
less than 10 years design life). Construction and O&M estimates are
summarized in Table 2-3.
2.6.1.1 Central watering point with individual haul of water, sewage,
and refuse. This involves the development of a safe water source from
which individuals will haul their own water. More than one source may be
needed in a larger community. In some instances it may be feasible to
develop a source at each dwelling. A self-haul system seldom results in
enough water at the homes for adequate personal and household sanitation.
In some instances it is feasible to provide septic tanks, waste
bunkers, or privies at each dwelling. In other cases users must be
responsible for delivering wastes to a central treatment and disposal
facility. Treatment and disposal of the wastewater could consist of a
lagoon or treatment plant. Refuse would usually be hauled (by indivi-
duals to a landfill or fenced disposal site.
Central watering points with individual hauling are lower in
initial cost but provide the least health improvement and convenience
compared to other types of facilities. Costs run from $250 000 to
-------
TABLE 2-3. COST OF WATER DISTRIBUTION AND SEWAGE COLLECTION FACILITIES IN COLD REGIONS (1977).
OPERATION AND
TYPE OF SERVICE CONSTRUCTION COST MAINTENANCE COSTS1 REMARKS
Individual-Haul
Vehicle-haul
$300 000
$500 000
$600/month
$70/month/house
Per facility
3
30 homes
Pipe Facilities 3
(with minimimal fire $35 000/house $50/month/house 30 to 40 homes
protection)
2 3
Central Facility with $900 000 $140/month/house 60 homes
Individual-Haul
2 3
Central Facility with $1 300 000 $180/month/house 60 homes
Vehicle-Haul
i
Amortization of initial construction costs is not included. However, cost for replacing
critical components • such as pumps, boilers, vehicles, etc., is included. i
2
Approximately $30/ family/month can be recovered by using coin-operated showers, saunas, washers,
and dryers. Additional costs can be recovered if nearby facilities such as schools can be
serviced directly.
3
Five to six people/house.
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2-50
$350 000 per facility. The number of watering points needed in a given
community will depend on how scattered the houses are, ground conditions
throughout the community, possible water sources, and other factors.
Individual-haul facilities also have the lowest O&M costs but
provide the least service. Costs of $500 to $950 per month per facility
are known. The variance is primarily due to the sophistication of the
water and sewage treatment facilities needed.
2.6.1.2 Central watering point with vehicle delivery of water and
collection of sewage and refuse. This involves the development of a safe
water source from which a community or contractor will deliver water to
storage containers in the users' buildings. Sewage is collected from
holding tanks or in "honeybuckets", and delivered to a treatment/disposal
facility. Refuse is also collected by vehicle and transported to a
disposal point. The sophistication of the plumbing within the individual
buildings can vary considerably, from individual pressure systems with a
full complement of plumbing fixtures to an open container.
Vehicle-haul facility costs will vary with the facilities
installed in the individual buildings, distance to the source/disposal
point, storage, and the truck fill point facility. Initial installation
costs vary from $450 000 to $550 000.
Operation and maintenance costs for vehicle-haul systems will
depend on the above items plus the sizing of the building and vehicle
storage and holding tanks. The O&M costs run between $60 and $80 per
house per month. In northern Canadian communities, total costs for
vehicle delivery and collection run between 1 and 2fc per litre, but the
cost to the consumer is subsidized by the government. Wheeled vehicles
seem to have a useful life of about four years in remote cold regions and
tracked vehicles even less. Vehicle-delivery systems are extremely
labour intensive (50 percent of total delivery cost), although this
usually provides several jobs in the community.
A typical cost breakdown for a vehicle-delivery system in the
Northwest Territories is: vehicle capital = 15 percent (four-year life),
vehicle O&M = 21 percent, garage capital = 9 percent (10-year life), garage
O&M = 5 percent, and labour = 50 percent (@ $13 per hour for two persons).
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2-51
2.6.1.3 Central facility watering point with laundry and shower
facilities. A central facility would provide water, laundering, bathing,
and toilet facilities. The fixtures and facilities are usually coin-
operated. "Honeybucket" wastes can also be deposited at the facility and
handled with the wastewater from the facility. More sophisticated
central facilities include incinerators for refuse disposal and treatment
of grey water for reuse.
The initial costs for a central facility with laundry, showers,
and water provided will depend primarily on the degree of water treatment
necessary and the type of sewage treatment and refuse disposal selected.
Either individual or vehicle-haul can be used in conjunction with a
central facility. A facility with individual-haul will cost from
$700 000 to $1 100 000 and serve about 60 dwellings. One providing
vehicle-haul would cost between $1 000 000 and $1 600 000 depending,
again, on the degree of fixture sophistication within the houses (type of
tanks, flush toilets, etc.). Central facilities which provide bathing
and laundry facilities would have to be financed and maintained by the
homeowners who would have the other fixtures in their homes.
The O&M costs of a central facility would be $65 to $80 per
family per month with individual-haul and $90 to $120 per family per
month with vehicle-haul. A part (approximately $30/family/month) of the
O&M costs for central facilities can be recovered by using coin-operated
saunas, showers, washers, and dryers. The remainder would have to be
collected by billing the users and/or coin dispensing of water. Some
costs can be offset by providing water and sewer service to nearby
facilities such as schools and health clinics.
2.6.1.4 Complete piped water delivery and sewage collection. Safe
water is distributed from the source to each building and sewage is
collected and transported to a treatment facility using above or below-
ground piped systems. Refuse is still collected by vehicle. Piped water
systems may provide fire protection or domestic consumption only. The
sewage collection system could be gravity, vacuum, or pressure operated.
Initial construction costs for complete piped facilities vary
greatly with the community layout and building density, soil conditions,
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2-52
whether an above or below-ground system is used and other factors.
Initial costs are higher than with the other alternatives but the
greatest health improvement and convenience is offered.
Costs usually run between $30 000 and $40 000 per house, includ-
ing the cost of service lines but not house plumbing. It would cost
another $2000 to add a sink, toilet and lavatory with the proper plumbing
accessories to an existing house. Piped facilities have lower O&M costs
than vehicle-distribution and collection systems. O&M costs range from
$40 to $65/family/month depending on the type of system used (i.e., above
or below-ground, pipe or utilidor, gravity, or pressure or vacuum),
labour costs, compactness of area to be served, and degree of treatment
needed. These costs do not include heating water or the electricity used
in the individual buildings for laundry and bathing.
2.6.2 Design life
For the most part, the design life for facilities and equipment
in cold regions is shorter than for the same units operated in more
temperate climates. This is especially true of equipment which must
operate outside in the winter. The following list presents some commonly
used design lives for cold regions:
Component; Design Life (years)
Wells 30
Pumps and controls 5
Boilers 5
Storage tanks 40
Water distribution lines 40
Meters 10
Valves 10
Septic tanks 5 to 10
Drainfields 5
Sewage collection lines 30
Lift stations (not pumps) 30
Trucks 4
Tracked Vehicles 2 to 3
Buildings 30
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2-53
Paint (outdoor) 10
Service connections 10 to 15
Backhoes (occasional use) 6 to 10
Compressors 5
2.7 Operation and Maintenance
2.7.1 Community and operator training
Where the community operates its own system, successful opera-
tion is very dependent upon the training and dedication of people in the
community, especially the operator. The operator's dedication and
acceptance of responsibility is a direct indication of how successful and
how long the facility will operate well. It is usually easier to ensure
proper operation for government-operated systems. Training must be
geared to the operator's education level. In remote areas, experience
has shown that training carried out with the individual operator at his
own plant is more successful (also, more expensive) than bringing several
operators to a central location or educational institution for training.
Probably a combination of individual and group training is desirable. At
least two operators should be trained for each facility to allow for
back-up when the main operator is not available. Operator training
should be provided in progressive levels, such as:
Level 1 would provide basic emergency measures to minimize
facility damage (e.g. to drain the system or start standby pumps
or boilers in case of a failure of an important part). It would
be desirable to have several people in the community trained to
this level.
Level 2 would provide training for minor repairs to boilers,
pumps, chlorinators, etc., to get them back on line, in addition
to the Level 1 responsibilities. This level would not include
much preventative maintenance, but would provide primarily day
to day operation. Both the main and standby operator should
have this level of training.
Level 3 would include Level 1 and 2 training, and preventative
maintenance, such as keeping the boilers in adjustment, ete. The
main operator should be trained to this level at least.
-------
2-54
Level 4 would provide capable and interested Level 3 operators
with training to a level where they would be able to qualify for
formal certification as water and sewage treatment plant
operators.
First priority would be Level 1 training and then on up to
Level 4. Most operators in remote native villages would not need Level 4
training. However, local laws or requirements may now, or in the future,
specify Level 4 training of all operators. At construction camps or
government installations it is probably desirable to train operators to
standards higher than those above because facilities are usually more
sophisticated.
Ideally, the operator and alternate operator should be selected
at the beginning of construction so they can receive on-the-job training
throughout construction. The selection should be made by the community,
with technical help from the constructing or training agency, because the
community must accept and support the operators after they assume O&M
responsibilities for the facilities. The operator should be selected for
dedication and abilities, not because of political connections within the
community. Operator training is not a one-time responsibility; it is
on-going. Operators move on to better jobs, community administration
changes and new operators are appointed, etc., making it necessary to
carry on a continuous training program. The operators must be paid
enough to keep them on the job and to provide a comfortable living.
Community education is also an important part of the training
process. The community must realize the importance of the operators and
support them morally as well as financially. A community appreciation of
the health and convenience benefits the facilities bring will promote
this support.
In a small community the operator may be responsible for
collection of the user fees. In large communities an administrative
staff handles collections, and this should be considered for any
community. It will be more difficult for an operator to hold the
community's support if he is also shutting off their water for
non-payment of bills.
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2-55
The community administration or the operator must be trained in
bookkeeping, billing, employment forms (tax withholding, workmen's
compensation, etc.), and the other functions needed to operate a utility.
The community must also pass and administer ordinances to regulate the
utilities. Homeowners must often be trained in the correct use and care
of the new facilities installed in their homes.
Whether or not O&M subsidies are provided, technical and
management help must always be available to the operator and community.
Occasional trips should be made to the community to meet with
the operator and discuss any problems he may be having with his facili-
ties. In cold regions it is important that one of these visits be made
in the fall so any problems or repairs that need to be made can be
done before winter, especially those that would jeopardize the integrity
of the system. On these visits, all critical components should be
inspected to make sure they (and their standby units) are operating
properly. Another visit should be during the summer when all lines can
be flushed and fire hydrants operated and cleaned.
2.7.2 Operation and maintenance manuals
Operation and maintenance manuals are extremely important if the
operator is to correctly care for his facilities [25], They should be
written during construction so that they are available for system start-
up. They should include many pictures of all components discussed.
Arrows can indicate exactly what part is being discussed. They must also
be written for the individual operator's education level and include:
1) accurate and complete as-built drawings (layout of system,
piping, diagrams, etc.);
2) complete parts list and suppliers' names and addresses for
all equipment, chemicals, etc., that must be maintained;
3) step-by-step troubleshooting lists of all possible problems;
4) step-by-step repair and maintenance lists for all equipment
and parts;
5) a good index so the operator can quickly find the items he
needs;
-------
2-56
6) the names and phone numbers of people the operator can call
day or night in case of an emergency that he is unable to
handle without help;
7) a definition of each part of the facility, what its function
is, and why it is important.
2.7.3 Reliability
The reliability of utility systems depends mainly on the quality
and quantity of the preventative maintenance performed by the operator.
Reliability is important because of the expense involved in replacement
or repair in remote areas in cold regions, and because of the consequences
of catastrophic failure of the entire facility because of the failure of
an inexpensive control. Reliability must be a major consideration in
selecting components and equipment. This includes the availability of
repair parts and service.
Because of the unreliability of power in cold regions, standby
generation capability must be provided for all critical components of a
facility.
A facility that is less automated and, therefore, needs more
operator attention will be very reliable if the operator is competent.
However, if he is not, a facility which is automated to a high degree
will prove more useful, in spite of the tendency for sophisticated
equipment to malfunction.
2.7.4 Management backup
In addition to training operators and making occasional visits,
a responsive backup system to help operators solve problems is essential.
This support involves helping the operator get parts he needs, helping
the bookkeeper work out problems, being readily available to help the
operators with technical advice and working out complex problems on-site,
responding with qualified people and materials during emergencies, and
making regularly scheduled visits several times a year to help the
operators maintain a sound preventive maintenance program.
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2-57
2.8 References
1. Ryan, William L., "Design and Construction of Practical Sanitation
Facilities for Small Alaskan Communities". Permafrost: The North
American Contribution to the Second International Conference,
National Academy of Sciences, Washington, D.C., 1973.
2. U.S. Public Health Service Monograph No. 54-1958. PHS Publication
No. 591, U.S. Government Printing Office, Washington, D.C., 1958.
3. Associated Engineering Services, Ltd., "Wabasca - Desmarais, Water
and Sanitation Feasibility Study", prepared for the Northern
Development Group, Alberta Executive Council, Government of the
Province of Alberta, 1974.
4. Gamble, D.J., "Unlocking the Utilidor", Proceedings of the Symposium
on Utilities Delivery in Arctic Regions, Environmental Protection
Service, Environment Canada, January, 1977 (Report No. EPS 3-WP-77-1).
5. Puchtler, Bert, "Water-Related Utilities for Small Communities in
Rural Alaska", Report to Congress authorized by Section 113 Public
Law 92-500, U.S. Environmental Protection Agency, Washington, D.C.,
1976.
6. Muller, Siemon William, Permafrost or Permanently Frozen Ground, and
Related Engineering Problems, J.W. Edwards, Inc., Ann Arbor,
Michigan, 1947.
7. Buvert, V.V. et al, "Snow and Ice as Materials for Road Construction",
translation # 54, U.S. Army Corps of Engineers, (CRREL), 1957.
8. Tomayko, D.J., "Elevated Snow Roads in Antarctica", The Military
Engineer, No. 429, January - February, 1974.
9. Clark, E., et al, "Expedient Snow Airstrip Construction Technique",
U.S. Army Corps of Engineers, Cold Regions Research and Engineering
Laboratory Special Report # 198, 1973.
10. Hansen, B.L., "Instruments for Temperature Measurements in Perma-
frost", Proceedings of the First International Permafrost Conference,
Purdue, 1963.
11. Crory, F.E., "Pile Foundations in Permafrost" Proceedings of the
First International Permafrost Conference, Purdue, 1963.
12. Penner, E., "Frost Heaving in Soils", Proceedings of the First
International Permafrost Conference. Purdue, 1963.
13. Berg, R., "The Use of Thermal Insulating Materials in Highway
Construction in U.S.", U.S. Army Corps of Engineers, Cold Regions
Research and Engineering Laboratory, Report # MP 539, 1974.
-------
2-58
14. Smith, D.W. and Justice, S.R., "Clearing Alaskan Water Supply
Impoundments. Management Laboratory Study and Literature Review",
Institute of Water Resources, Report No. IWR-67, University of
Alaska, Fairbanks, 1976.
15. Carlson, A.R., "Heat loss and Condensation in Northern Residential
Construction", and "Design of Floors for Arctic Shelters",
Proceedings of Symposium on Cold Regions Engineering, University of
Alaska, College, Alaska, 1971.
16. Floyd, P., "The North Slope Center: How Was It Built?", The
Northern Engineer, Vol. 6, No. 3., 1974.
17. Tobiassion, W., "Deterioration of Structures in Cold Regions",
Proceedings of the Symposium on Cold Regions Engineering, University
of Alaska, College, Alaska, 1971.
18. ASHRAE Handbook of Fundamentals (latest edition), American Society
of Heating, Refrigerating, and Air Conditioning Engineers, Inc.
19. Pritchard, G.B., "Foundations in Permafrost Areas", Proceedings of
the First International Permafrost Conference, Purdue, 1963.
20. Tobiasson, W., "Performance of the Thule Hanger Soil Cooling
System", Proceedings of the Second International Permafrost
Conference, Yakutsk, USSR, 1973.
21. Miller, J.M., "Pile Foundations in Thermally Fragile Frozen Soils",
Proceedings of the Symposium on Cold Regions Engineering, University
of Alaska, College, Alaska, 1971.
22. Seeding Recommendations for Revegetation of Arctic and Subarctic
Soils, personal discussions with U.S. Dept. of Agriculture, Soil
Conservation Service, Anchorage, Alaska; Institue of Agriculture,
University of Alaska, Palmer, Alaska; and Alaska State Division of
Aviation, Anchorage, Alaska, 1974.
23. Hamelin, L.E., "A Zonal System of Allowances for Northern Workers",
MUSK-OX, Publication 10, 1972.
24. Gordan, R., "Batch Disinfection of Treated Wastewater with Chlorine
at Less than 1°C.", U.S. EPA # 660/2-73-005, September 1973.
25. Squires, A.D., "Preparation of an Operations and Maintenance
Manual", In Symposium on Utilities Delivery in Arctic Regions,
Proceedings published as Environmental Protection Service Report No.
EPS 3-WP-77-1, Environment Canada, January, 1977.
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2-59
2.9 Bibliography
Alaska Department of Commerce and Economic Development, Directory of
Permits, Juneau, Alaska, 1978.
Christensen, Vern, and Reid, John, "N.W.T. Water and Sanitation
Policy and Program Review", Department of Planning and program
Evaluation, N.W.T., Canada, December, 1976.
Cooper, I.A., and Rezels, J.W., "Vacuum Sewer Technology", prepared
for the U.S. EPA Technology Transfer Seminar Program on Small
Wastewater Treatment Systems, 1977.
Grainge, J.E., and Shaw, J.W., "Community Planning for Satisfactory
Sewage Disposal in Permafrost Regions", paper presented at Second
International Symposium on Circumpolar Health, 1972.
Grainge, J.W., "Study of Environmental Engineering in Greenland and
Iceland", Canadian Division of Public Health Engineering, Department
of Health and Welfare, Report No. NR-69-5, 1969.
Heinke, G.W., "Report on Environmental Engineering in Greenland and
Northern Scandinavia", Dept. of Civil Engineering, University of
Toronto, October, 1973.
Kreissl, J.F., "Status of Pressure Sewer Technology", prepared for
the U.S. EPA Technology Transfer Design Seminar for Small Flows,
1977.
Simonen, E., and Heinke G., "An Evaluation of Municipal Services in
the Mackenzie River Delta Communities", Publication No. 70-60 Dept.
of Civil Engineering, University of Toronto, 1970.
Tsytovich, N.A., The Mechanics of Frozen Ground, McGraw-Hill and
Scripta Book Company, New York, 1975.
-------
SECTION 3
WATER SOURCE DEVELOPMENT
Index
Page
3 WATER SOURCE DEVELOPMENT 3-1
3.1 General 3-1
3.2 Water Sources 3-3
3.2.1 Surface water 3-3
3.2.2 Groundwater 3-6
3.2.3 Other water sources 3-9
3.3 Water Requirements 3-10
3.3.1 Water usage 3-10
3.3.2 Demand factors 3-14
3.3.3 Fire flows 3-15
3.3.4 Water quality 3-15
3.4 Structures 3-18
3.4.1 River intakes 3-18
3.4.2 Infiltration galleries 3-22
3.4.3 Wells 3-26
3.4.4 Pumping stations 3-28
3.4.5 Transmission lines 3-31
3.5 References 3-31
3.6 Bibliography 3-32
-------
List of Figures
Figure Page
3-1 Hydrograph of Mean Daily Discharge, Kuparuk River 3-4
3-2 Computer Simulation of the Effect of a River on
Permafrost 3-8
3-3 Hourly Peak Water Demand in Small Cold Climate
Communities 3-15
3-4 Water Quality in Upper Isatkoak Lagoon, Barrow,
Alaska, 1975-1978 3-19
3-5 Water Truck Filling at Water Lake at Cambridge Bay, NWT 3-20
3-6 Water Intake at Fort MePherson 3-20
3-7 Intake House in Peel Channel at Aklavik 3-20
3-8 Piping Schematic for Water Intake 3-21
3-9 Water Intake Schematic 3-23
3-10 Supply Utilidor at Coppermine, NWT 3-24
3-11 Infiltration Galleries 3-25
3-12 Well Seal 3-29
3-13 Pumphouse at Williamson Lake in Rankin Inlet, NWT 3-30
3-14 Pump Station 3-30
List of Tables
Table Page
3-1 Recommended Water Usage 3-12
3-2 Examples of Actual Water Use 3-13
3-3 Fire Flow, Fire Reserve and Hydrant Spacing Recommended
by the National Board of Fire Underwriters 3-16
-------
3-1
3 WATER SOURCE DEVELOPMENT
3.1 General
Cold climate conditions require special attention when selecting
and developing water sources. Hydrologic conditions in northern latitudes
differ from those in sourthem regions in several important respects.
This is true of both groundwater and surface water in areas of continuous
permafrost. Throughout much of the cold region of North America, precipi-
tation is light, terrain in populated regions is relatively flat, and
yearly runoff is concentrated in the short period during ice breakup.
There are many small, shallow lakes and ponds and numerous rivers and
creeks. Ice cover varies according to local conditions, but generally
lasts from six to 10 months. Hydrologic data on northern lakes, streams
and groundwater are scarce and typically cover periods of short duration.
This makes it difficult to predict reliable yields for water supply
purposes.
Permafrost is impermeable for all practical purposes. Runoff
from melting and precipitation tends to occur in a shorter period and is
more complete than in areas without permafrost. This phenomenon also
greatly reduces the recharge of aquifers. Any construction in permafrost
regions requires special consideration and unique engineering, particularly
in regard to cost and the technical problems of maintaining water flow.
Often, permafrost conditions prevent the application of standard techni-
ques and preclude the development of available groundwater sources. The
costs of developing, maintaining, and operating a water source in cold
climates are greater in all respects than in temperate regions. Costs
will vary with each location; however, they generally increase with
decreasing mean annual temperature and remoteness of the site.
Regardless of the apparent merits of a source under consideration,
there is no substitute for detailed preliminary engineering studies and
direct observation of local conditions prior to final selection. Some
type of water source may be developed in virtually any part of the cold
region of North America, but the physical difficulty of operation and
maintenance or the associated costs may be highly unattractive.
-------
3-2
The governments of both the United States and Canada support the
collection and publication of basic data of value in planning water
supply systems.
The Canadian Department of Environment publishes an annual
report entitled "Surface Water Data - Yukon and Northwest Territories",
which lists stream flows at selected stations in the Northwest
Territories. This publication is prepared by:
Inland Waters Directorate
Water Survey of Canada
Environment Canada
Ottawa, Ontario K1A OE7
The annual U.S. Government publication, "Water Resources Data for
Alaska", includes information on stream flows and water quality for
selected streams. This publication is available from:
U.S. Geological Survey
District Chief, Water Resources Division
218 "E" Street
Anchorage, Alaska 99501
In addition to these publications, special reports may be
available from the U.S. Geological Survey agency on particular locations
dealing with short-term data, groundwater, or special water quality
studies. Both nations maintain agencies concerned with weather and other
climatological factors which regularly publish their data. One example
is "Ice Thickness Data for Canadian Selected Stations". Precipitation is
also recorded and published. For this information the following offices
should be contacted:
Atmospheric Environment Service
Environment Canada
Ottawa, Ontario K1A OH3
National Weather Service Forecast Office
632 6th Avenue
Anchorage, Alaska 99501
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3-3
3.2 Water Sources
Water in cold regions comes from the same basic sources as in
temperate areas, but there are some peculiarities to arctic and subarctic
surface and groundwater hydrology which merit comment.
3.2.1 Surface water
Surface water results from precipitation and snowmelt and is
replenished through the hydrologic cycle. In northern latitudes surface
waters in shallow lakes and small streams may be effectively eliminated
in the winter because of complete freezing. Larger streams and deep
lakes may remain liquid beneath an ice cover but flows and volumes are
reduced since there is no contribution from precipitation until warm
weather returns. In some cases, pressure between the stream bed and
downward-growing ice cover forces flows to the surface through cracks and
along the shores where it then freezes. Frozen water of this type is
called "aufeis" and is essentially not available until breakup and thaw
occur. This has a smoothing effect on the runoff hydrograph by reducing
the peak and increasing the flow during the melt. Large snow drifts also
contribute to runoff in this manner. Thus, it becomes apparent that
because of the cold climate and quantity of ice, not all surface sources
are available for continuous water supply. Sources which are suitable
for continuous supply are large rivers and large lakes. Figure 3-1 shows
a hydrograph for a typical medium-sized arctic river.
3.2.1.1 Rivers. Rivers are an excellent water source in winter
because sediment transport is minimal and overland flows, which tend to
lower water quality, do not occur. The disadvantages of rivers as a
supply source include low water temperatures and flowing ice during
freeze-up and break-up periods, which may damage or destroy water intake
structures. Also, in alluvial streams it is difficult to locate a
permanent channel beneath the winter ice.
Summer river flows, which tend to be much higher, frequently
contain sediments or glacial flour from overland runoff or melting
glaciers which cause difficult treatment problems.
3.2.1.2 Lakes. Lakes may be a good continuous source of water,
depending upon the size (area and depth) and the severity of the climate.
-------
100,000
CO
co"
o>
O)
CO
_c
,o
CO
"CO
"D
c=
CO
CD
10,000
1000
100
1970
1971
10.0
1.0
_CD
1
X
CO
O
c
13
U)
I
0.1
June
July
August
September
FIGURE 3-1. HYDROGRAPH OF MEAN DAILY DISCHARGE, KUPARUK RIVER
(Data Source: U.S. Geological Survey).
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3-5
Shallow lakes may freeze to the bottom in arctic regions or may
freeze-concentrate impurities below the ice to the extent that the water
is no longer of acceptable quality. Ice formation is proportional to the
air temperature. A general expression of this phenomenon is called
Steffan's equation:
/2k~l7 (3-D
A - ;
V L
in which: X = ice thickness,
If = freezing index,
L = volumetric heat of fusion of water,
k = thermal conductivity of ice (see Section 15).
Impurities, such as most salts, are rejected from the freezing
water, making the ice relatively pure. The more slowly ice is formed,
the more efficient this process becomes. The net effect of this pheno-
menon is that impurities become concentrated in the water beneath the
ice. It may be generalized that if the liquid content of a lake or pond
is reduced 50 percent by ice formation, dissolved salt concentrations
will double. Careful thermal and chemical analyses are required to
identify a lake or pond which may freeze deep enough to create this
condition. (For details see Section 15.)
3.2.1.3 Watershed yield and quality improvement. The amount of water
yielded by a given watershed is related to the precipitation received by
the watershed. Other factors which influence yield are evaporation to
the atmosphere and transpiration by vegetation.
To estimate runoff or yield, records of the precipitation,
evaporation and temperature are needed. The agencies listed in Section
3.1 maintain current data for many locations. Some agencies, such as the
U.S. Geological Survey, calculate and publish watershed yields for
specific stream locations. When no other information is available these
data should be used as a guide. For large projects where accurate
information is critical, data should be collected for several years prior
to final design to assure that the required yield will, in fact, be
available.
-------
3-6
In cold regions, particularly in the Arctic, most precipitation
is in the form of snow. However, due to winds it does not necessarily
remain where it fell initially. This fact has been used to increase the
annual water yield of small watersheds by inducing the occurrence and
growth of snow drifts. Near Barrow, Alaska the U.S. Army augmented the
fresh water supply by using snow fences. This work provided valuable
information for evaluating the technique. Accumulation of at least 10.1
o
mj of water for every metre of 1.5-metre high snow fence is possible.
The cost of this water (in 1975) indicated that over a 10-year amortiza-
tion period for snow fences, 0.2 m^ of water could be produced annually
for about one penny [1].
In some areas it may be more economical to develop only an
intermittant source and depend upon artificial storage for periods when
the natural supply is low, e.g., when all surface water freezes during
the winter, or during periods of highly turbid river water.
3.2.2 Groundwater
Groundwater may be considered the most desirable source of water
in cold regions for several reasons. Normally, groundwater temperature
in the winter is warmer than surface water and is nearly constant
year-round. Mineral quality of groundwater is more constant than surface
water. Also, subpermafrost groundwater is almost always a year-round
source of supply, so that alternate or dual source systems need not be
developed.
The cost of exploring, drilling, developing and maintaining
wells in cold remote areas can be high.
3.2.2.1 Groundwater in permafrost. Groundwater in areas of continuous
permafrost may be found in three general locations: 1) above permafrost,
within the active layer (suprapermafrost); 2) within permafrost in thawed
areas (intrapermafrost); and 3) beneath permafrost (subpermafrost).
Waters found in the active layer above the permafrost are
generally unsuited for potable water supplies without extensive treat-
ment. Such water is usually found within three to eight metres of the
surface and frequently has a high mineral content. Because they are
shallow, such aquifers are also subject to contamination from privies and
-------
3-7
septic tanks. The quantity of this water source is often low and
unreliable. A system for use of suprapermafrost water was developed for
Port Hope, Alaska [2].
Intrapermafrost water is quite rare and usually very highly
mineralized. Such water must contain high concentrations of impurities
which depress the freezing point below that of the surrounding perma-
frost. There is no reliable method to locate pockets of intrapermafrost
water with present state-of-the-art techniques. For these reasons it is
not normally a suitable water source.
Subpermafrost groundwater is the most reliable and satisfactory
groundwater source in permafrost regions. Recharge of subpermafrost
aquifers occurs beneath large rivers and lakes where there is no
permafrost. In general, when fine-grained soils are frozen the movement
of groundwater is effectively prevented. Satisfactory wells have been
located near rivers or large lakes since the ground in these areas may
not freeze.
Subpermafrost groundwater is generally deficient in dissolved
oxygen. As a result, high concentrations of some salts, such as those of
iron and manganese which may readily dissolve under these conditions, are
present. Hardness is also common in subpermafrost groundwater.
Occasionally groundwater will contain dissolved organic materials in
addition to hardness, iron and other minerals.
Costs for drilling and well maintenance are higher in permafrost
areas. The water must be protected from the cold permafrost and the
permafrost needs to be shielded from the heat of the water. This often
requires special well castings, grouting methods and heat-tracing water
lines, all contributing to increased cost.
A computer simulation of the effect of a meandering river on
permafrost has been developed [3]. Figure 3-2 shows a typical example of
this type of calculation. The application of this information is greater
for groundwater development than for surface water. A well might
conceivably be located where it would penetrate an aquifer being
continuously recharged by a river.
3.2.2.2 Estimation of groundwater yield. The predictable yield of
groundwater from a watershed may be estimated in a manner similar to that
-------
Depth (metres)
Depth(metres)
Depth(metres)
CD
00
o
O)
o
CD
CD
Ol
IV)
o
o
CD
o
o
u>
CO
05
o
o
CD
01
o
CD
O)
to
o
en
o
CD
(D
(Q
o
-------
3-9
for estimating surface runoff. The concept involves balancing all inputs
with the withdrawals. In practice, however, measuring the inputs and
withdrawals may be quite complex.
The safe groundwater yield (Y ) is equal to the watershed
o
precipitation (P), less surface flow out of the watershed (Q ), less
s
evapotranspiration (E) plus the net groundwater inflow (Q ), less the
o
net change in surface storage (AS), less the net change in groundwater
storage (AG).
Thus,
Y =P-Qs-E+Q -AS-AG (3-2)
Only two terms in the above equation can be measured with reasonable
accuracy, P and Q ; the others must be estimated. Recharge of
s
aquifiers in permafrost regions is much more limited than in other areas
because permafrost may be an impermeable barrier. Hydrologists experienced
in cold region work should be consulted when estimates must be accurate.
3.2.3 Other water sources
Snow, ice, and direct catchment of rainfall are potential water
sources which may be considered for small or temporary establishments.
3.2.3.1 Snow and ice. In general, the natural quality of these
sources is high but contamination of the ice or snow stockpile is a real
hazard. Also, the cost of melting is significant and there are added
costs for harvesting and storing equipment and melters. If significant
quantities of waste heat are available (e.g. from a nearby power plant),
this method may be more attractive.
Induced snow drifting may improve the feasibility of using snow
as a source of water. However, unless the need is temporary and the
population to be served is small, direct melting will not be practical.
Large volumes of snow are required to obtain even small quantities of
water and the cost of snow melting is high. It has been estimated that
approximately one litre of "Arctic" diesel is required to produce 70
litres of water from snow [4]. In addition to fuel cost, labour for
operating snow melters and snow harvest equipment must be considered.
Slaughter et al. [1] concluded that parallel snow fences spaced
50 to 100 meters apart would trap a maximum amount of snow. Fences
should be erected so that they concentrate drifts near stream channels to
-------
3-10
assure a better runoff and easier collection. Fences between 1.5 and
3.6 metres high have been used in various configurations. Each installa-
tion should be designed to fit the local situation.
3.2.3.2 Seawater and brackish water. Desalinated seawater has been
used for domestic supply but the associated problems are considerable.
Intakes in the ocean or on the beach are subject to ice forces of pheno-
menal magnitude. Ice scour of beaches at all times during the year must
be considered because of combinations of wind and sea ice. During the
winter months, shore-fast ice and frozen beaches pose special problems.
The largest drawback is that there are no economical (from an operating
and management standpoint) methods to desalinate seawater on the scale
necessary for a small community or camp.
Brackish water with total dissolved solids (IDS) of < 10 000
mg/L is occasionally the only source available. Such waters may be
treated by reverse osmosis or distillation but significant problems must
be anticipated at small installations.
3.2.3.3 Water reuse. In the absence of ample supplies of fresh water,
water reuse may be considered. In Alaska, bath and laundry water are
reclaimed and reused at several locations for toilet flushing and other
non-potable purposes (see Section 11 for more details). Regeneration of
potable waters is not yet state-of-the-art technology but it is logical
to work toward that end in areas of extreme water shortage. Seawater
contains approximately 35 times more dissolved solids than domestic
sewage. The effluent from existing secondary or tertiary sewage treat-
ment plants is basically free from suspended materials and should be more
economical to treat than seawater [5],
3.3 Water Requirements
3.3.1 Water usage
The amount of water used by inhabitants of northern communities
depends on several factors. Cultural background is particularly impor-
tant since many cold climate communities are populated by Indians and
Eskimos. Traditionally, native people have not had access to large quan-
tities of water and as a result they tend to use water conservatively.
However, as water becomes available, it is used more freely. In construe-
-------
3-11
tion camps, workers may use large quantities of water but this, too,
depends on the nature of the camp. Residents of temporary camps use less
water than in base camp situations. Availability (or installation) of
plumbing fixtures is another factor which influences use, perhaps more
than any other factor.
The minimum amount of water considered adequate for drinking,
cooking, bathing and laundry is 60 L per person per day. Even this may
be difficult to achieve where piped delivery is not practical or possible.
Current experience indicates that in communities without residential
pressure systems which have "honeybag" waste systems water consumption is
approximately 4 to 12 L/person/d.
Analysis of three years of data collected at Wainwright, Alaska,
indicated that water use in homes rose from about 2 L/person/d in January
1974, to about 5.5 L/person/d in December of 1976 and the upward trend
appears to be continuing. Wainwright, however, has a central facility
which provides for bathing and laundry away from the home which was not
included in these figures. In spite of these apparently low quantities
for household use, significant health benefits have been observed in the
village from improved water quality and sanitation facilities.
Table 3-1 presents water use factors for various types of
communities in cold regions.
Water conservation. Even though these recommended quantities
are recognized as adequate, many communities in Alaska and Canada consume
large quantities of water which are essentially wasted. Table 3-2 gives
examples of water use showing excessive quantities in many cases.
System designers must be alert to the possibilities for conserv-
ing water and potential reasons why systems sometimes encourage waste.
Water and its treatment costs money, as do sewers and sewage treatment
which must handle the hydraulic loads. Appendix B summarizes the various
household water conservation fixtures, including toilet systems.
Bleeding. Users must be discouraged from allowing water to run
to prevent freeze-up of service lines. This type of wastage is most
common in the spring when frost penetration is greatest. To compound the
problem, water sources are lowest in early spring. Subarctic cities seem
to be more prone to this situation, probably because service lines in the
-------
3-12
TABLE 3-1, RECOMMENDED WATER USAGE
Litres/person/day
Households Average Normal Range
1. Self-haul from watering point <10 5-25
2. Truck System
a) non-pressure water tank, bucket toilet and 10 5-25
central facilities
b) non-pressure water tank, bucket toilets, and 25 10 - 50
no central facilities
c) non-pressure water tank, waste holding tank 40 20 - 70
d) pressure water system, waste holding tank and 90 40 - 250
normal flush toilet*
3. Piped System** (gravity sewers) 225 100 - 400
4. Piped System (vacuum or pressure sewers) 145 60 - 250
5. Well and Septic Tank and Tilefield 160 80 - 250
Institutions (piped system)
School: day student 10 2-18
boarder 200 100 - 400
Nursing Station or Hospital: per bed 100
Hotels: per bed 100
Restaurants, Bars: per customer 5
Offices: 10
Central Facilities:
Showers (2 per person/week) 10
Laundry (2 loads/family/week) 7
Work Camps
Base Camp 200
Drilling pad 130
Temporary, short duration camps 100
* Conventional flush toilets not to be permitted with truck system in future.
** xhe figures for piped systems do not make allowances for the practice of
letting fixtures remain open in cold weather to provide continuous flow
in watermains to prevent freezing. Water use under that practice used
only in older systems may be as high as several thousand litres per
person per day.
-------
3-13
TABLE 3-2. EXAMPLES OF ACTUAL WATER USE
City
Minto, Ak.
Anchorage, Ak.
Unalakleet, Ak.
Dot Lake, Ak.
Homer , Ak .
Seward, Ak.
Bethel, Ak.
Dillinghara, Ak.
Seldovia, Ak.
Kenai, Ak.
Palmer , Ak .
Fairbanks , Ak .
Clinton Creek, Y.T.
Dawson City, Y.T.
Mayo, Y.T.
Whitehorse, Y.T.
Faro, Y.T.
Inuvik, NWT (1976)
Inuvik, NWT (1970)
Resolute Bay, NWT
Resolute Bay, NWT (1970)
Yellowknife, NWT
Yellowknife, NWT
Aklavik, NWT
Fort McPherson, NWT
Edmonton, Alberta
Litres/
person/
day
190
890*
300
190
1630*
4500**
2300**
270
2300*
680*
380
760*
650*
1140*
6400**
1700*
1680*
1140*
485-550
20
163
23
485
90
63
250
236
Approx.
number of
people
180
120 000
400
50
1 200
25 000
381
745
462
11 217
—
3 500
1 300
160
10 000
600
850
500 000
Type of System
Circulating water - gravity
sewers
Conventional water and
gravity sewers
same as Minto
Central heat - conventional
water, individual sewer
Conventional water and
gravity sewers
Conventional water and
gravity sewers (winter)
(summer)
Circulating water and gravity
pressure sewer
Conventional water and gravity
sewer
same as Dillingham, Ak.
same as Dillingham, Ak.
same as Dillingham, Ak.
Circulating water and gravity
sewer
Circulating water and gravity
sewer
Circulating water and gravity
sewer
Circulating water and gravity
sewer
Circulating water and gravity
sewer
Circulating water and gravity
sewer
Circulating water and gravity
sewer
Trucked water, honeybags
Circulating water
Trucked water, honeybags
Piped water, gravity sewer
Trucked water, sewage pumpout
Summer piped system
Piped portion of community
Conventional, residential
only
* some water wasting
** indicates leakage in old water pipes
-------
3-14
Arctic are better designed for low temperatures and are usually heated or
recirculated. Four remedies for this problem are to:
1) educate water users,
2) meter all customers (services),
3) provide inexpensive and quick methods of thawing
frozen service lines,
4) construct service lines that are less apt to freeze.
Item 4) is the most important; keys to its accomplishment are:
a) bury lines below frost line until within the thaw bulb of
the house,
b) insulate lines if there is a possibility of the surrounding
ground freezing,
c) recirculate the water in service lines,
d) provide heat tapes on lines in frost zone,
e) add heat to water in distribution system.
Leakage. A lot of water is wasted because of leakage from old
or broken service lines and mains and because of poorly maintained plumb-
ing within buildings. Possible methods of minimizing losses of this kind
are to:
1) maintain pressure in mains at the lowest pressure
necessary (about 25 psi, 172.5 k Pa),
2) promptly repair all leaks in mains and service lines,
3) check system for leaks frequently by isolating sections and
pressure testing,
4) educate users on the causes of each and train them to repair
leaking fixtures such as faucets and toilets.
3.3.2 Demand factors
Factors used for computation of peak demand in small systems in
cold regions will be somewhat higher than in temperate regions and for
larger communities.
Maximum daily demand should be computed at 230% of the average
daily demand. Maximum hourly demand should be computed at 450% of the
annual average daily demand.
-------
3-15
Figure 3-3 is presented for estimating hourly peak water demand
in small cold climate communities.
o
CD
in
~O
tz
ro
E
CD
T3
^
CO
CD
Q_
Above 50 dwelling units
Demand = [7 9 + 0076(N-50)]
Where N = No of dwelling units
Demand = Peak flow in litres/sec
40 60 80
Number of dwelling units
100
120
FIGURE 3-3. HOURLY PEAK WATER DEMAND IN SMALL COLD CLIMATE COMMUNITIES
3.3.3
Fire flows
In larger towns and cities water available for the fire flows
should meet requirements of the National Board of Fire Underwriters (see
Table 3-3). In smaller northern communities this is not feasible because
of the distribution system such flows require. Because of the overall
demand where only marginal sources of potable water exist, separate systems
may be considered which would use untreated water such as seawater or river
water in a normally dry fire system. This subject is covered in Section 12.
3.3.4 Water quality
Water quality is equal in importance to any aspect of public
utility concern. Where the water source is concerned, however, quality
need not be given highest priority since raw water can be treated to make
it potable.
-------
3-16
TABLE 3-3. FIRE FLOW, FIRE RESERVE AND HYDRANT SPACING RECOMMENDED
BY THE NATIONAL BOARD OF FIRE UNDERWRITERS
Population
1 000
9 nnn
Z UUU
4 000
(. nnn
D UUU
10 000
1 1 nnn
_L j UUU
17 000
o o nnn
27 000
/. n nnn
t-U UUU
c c nnn
J J UUU
7 s nnn
Q R nnn
7 J UUU
i 9n nnn
_LZU uuu
i ^n nnn
J.JU UUU
9nn nnn
zuu uuu
Fire
gpm*
1 000
i >;nn
1 JUU
2 000
2c;nn
JUU
3 000
3cnn
JUU
4 000
A ^nn
** JUU
5 000
6 nnn
UUU
7 nnn
/ uuu
8 nnn
uuu
9 nnn
uuu
i n nnn
_LU UUU
Unnn
uuu
i 9 nnn
_i_z uuu
Flow
mgd*
1.4
9 9
Z. Z
2.9
0 £
J.O
4.3
5n
.U
5.8
A ^
o. j
7.2
8£
. o
in i
1U. 1
Uc
. J
iin
1J . U
1 L L
it . t
1 ^ H
-L J . O
17 ^
i/ . J
Fire
Reserve
MG*
0.2
Oc
. J
1.0
1 C
1 . J
1.8
9 1
Z.I
2.4
9 7
Z. /
3.0
i ^
J.o
/i 9
4 . Z
A Q
t- . o
^ A
J.H
A n
A ft
7 ?
1 • {-
Area
Engine
Streams
120 000
110 000
100 000
90 000
85 000
sn nnn
ou uuu
7n nnn
/ u uuu
An nnn
c c nnn
J J UUU
/, Q nnn
/. o nnn
/, n nnn
per Hydrant,
sq ft*
Hydrant
Streams
100 000
on nnn
yu uuu
85 000
70 nnn
/ o UUU
70 000
55 000
40 000***
o
* Conversion factors: gpm x 5.450 = m /d
mgd x 4.381 x 10~2 = m3/s
MG x 3785 = m3
sq ft x 0.0929 = m2
** For populations over 200,000 and local concentration of streams, see
outline of National Board requirements.
*** For fire flows of 5000 gpm and over.
The concern for quality of a water source is based primarily
on the ease with which the water may eventually be treated and the cost
for the treatment required. Reliability in quality is of equal
importance to reliability in quantity.
Groundwater quality. Water taken from above permafrost (supraper-
mafrost water) must be considered of questionable quality since contamina-
tion by pit privies and septic systems can easily occur. Subpermafrost
waters are generally unpolluted but may contain high concentrations of
iron (as high as 175 mg/L), magnesium and calcium as well as organics.
-------
3-17
Iron and hardness below 7 mg/L and 100 mg/L, respectively, are reasonably
easy to remove during treatment and do not detract from the value of the
source. In the highly mineralized areas of Alaska, some groundwaters
have been found to contain unacceptably high quantities of arsenic.
Extremely high concentrations of nitrates have been observed in other
groundwaters near Fairbanks, Alaska, and Nunivak Island.
Surface water quality Surface waters are more readily polluted
by man; thus emphasis should be placed on bacteriological and biological
quality of the water and watershed. It has been demonstrated that
bacteria live for long periods in cold waters and pose a potential health
problem for significant distances downstream from their entry point.
Water sources should be selected and the watershed protected in
a manner acceptable in any climate. The U.S. Public Health Service [6]
divides water sources into three categories: Group I water may be used
as public water supplies without treatment; Group II water may be used
after disinfection only; and Group III waters require complete conven-
tional treatment including coagulation, sedimentation, filtration and
disinfection. Because of the high probability of contamination of
surface waters by wild and domestic animals harboring various tapeworms
which cause hydatid disease in man, it is recommended that all surface
waters be filtered prior to use in the public water supply.
Surface water sampled for quality during warm weather may
indicate misleading values. Freeze-rejection of minerals and other
impurities during ice formation causes the remaining liquid to be of
significantly poorer quality.
Lake water quality improvement. It may be possible to improve
the quality of water in a small saline pond or lake by pumping out the
concentrated brines which remain under the ice near the end of the winter
and allowing fresh spring runoff to replace it. Repeated one or more
times, this method may permit the use of an initially unacceptable water
body as a source of supply. The U.S. Public Health Service, in develop-
ing an improved water source for Barrow, Alaska, used this method with
good results. Total dissolved solids concentration in the lagoon was
about 7000 mg/L when ice cover was fully developed. The range of total
-------
3-18
dissolved solids in the lake is shown in Figure 3-4. In April 1976, 326
million litres of brine was pumped from beneath the ice, resulting in
water of much higher quality.
3.4 Structures
Structures relating to water supplies range from a simple
temporary intake on river ice to a complex dam on permafrost with a year-
round intake and pumping station. Wells and their appurtenances are
also considered as supply structures.
It is not the intent of this discussion to provide a guide for
structural design of any facility but rather to point out features which
may require special attention in cold climates. Designs should be
prepared by engineers qualified to work in cold regions.
3.4.1 River intakes
Intake structures may be either temporary or permanent.
Permanent structures are more desirable because they permit a certain
freedom from attention at critical times such as during freeze-up and
breakup. On the other hand, temporary structures may be less expensive
and permit a degree of latitude of operation not afforded by permanent
structures. Also, because temporary facilities may require attention
during critical times of the year, they force the operator to become
aware of existing or potential problems.
Depending upon the overall system design and source capabili-
ties, intakes may only be required for a short period each year. If
demands are such that they cannot be met by providing storage, then more
elaborate intake works will be required.
Under some conditions a protected pump on the river shore or on
the ice may suffice. This requires little design attention or continuing
operator attention (see Figures 3-5, 3-6 and 3-7). The reverse is true
of permanent intakes.
Numerous arrangements and configurations of river intakes have
been designed with varying degrees of success. Figure 3-8 shows the
piping schematic for a matched pair of intakes in the Great Bear River at
Ft. Norman in the Northwest Territories. Such designs are continually
evolving to make use of more sophisticated concepts and materials.
-------
o
o
o
o
Total dissolved solids (mg/L)
O
O
O
W
O
O
O
O
o
o
Ol
o
o
o
CO
-j
en
W
o
•8
2
c
I
Ul
I
00
CD
-vj
en
o
D
CD
CO
O
CD
~-J
CD
Brine pumped from beneath the ice
during this period
Spring break-up
Spring break-up
O
CD
2, >
CD 2)'
-^1 CO
O CD
S W
CD ^
Q- ^
(U CD
oi
CO 2-
CD" »
< T
CD
o =
3
CO
Spring break-up
-------
3-20
FIGURE 3-5. WATER TRUCK FILLING AT WATER
LAKE IN CAMBRIDGE BAY, NWT
FIGURE 3-6. WATER INTAKE AT FORT McPHERSON
NWT '
FIGURE 3-7
INTAKE HOUSE IN PEEL CHANNEL
AT AKLAVIK, NWT
-------
-------
3-22
Open water intakes in cold regions are jeopardized by flowing
ice during freeze-up and breakup and must be given special attention.
Figures 3-9 and 3-10 show a water intake at Cambridge Bay in the
Northwest Territories of Canada. Note that the intake line is installed
to allow water to flow to the wet well by gravity so that even if the
intake itself were damaged, water would remain available at the pump.
Note also the construction details, such as insulation, wet well heater,
heat trace for intake line and recirculation line from townsite.
Use of multiple intakes is a recommended approach which may
enhance system reliability. An intake normally submerged in the summer
may be high-and-dry late in the fall when streamflow has been reduced by
freezeup. Further reason for multiple intakes is the option that
provides for continuously circulating water to minimize ice cover and
prevent freezing of the intake system.
Frazil ice is a phenomenon which occurs during freeze-up and
creates problems for operation of river intakes in open water. Frazil
ice occurs as ice forms in flowing water which is slightly colder than
0°C (supercooled) and from which heat is continually being lost.
Frazil ice adheres to and builds up on any submerged object it contacts,
including itself. Thus intake screens, trash racks and the like may
become choked by frazil ice in a matter of hours. Frazil formation can
be prevented by locating the intake in a reach of river where surface ice
forms before the water is supercooled, such as in a long, calm reach.
Surface ice cover prevents rapid heat loss from the water and thus
precludes frazil formation. Heating the intake works bar screens and the
like to 0.1°C will remove supercooling properties and prevent frazil
ice accumulation.
3.4.2 Infiltration galleries
Infiltration galleries offer some advantages over conventional
river or lake intakes. The most obvious is to remove the structure from
the river and the hazards imposed by ice during freeze-up and breakup.
Infiltration galleries may be placed in the thaw bulb of streams in
permafrost areas and collect water even when the streams appear solidly
frozen. Usually some flow of water will occur within the streambed
itself, particularly when the bed material is relatively coarse.
-------
-packed PO-r^ne *****
Normal water level
Estimated low water level
Chain hoist
Electric space heater
HWL-4J1
—
Vertical turbine
supply PumPs
Estimated bottom of
ice level intake
Electrical panel
polystyrene insulation
trace cable
HWL TV:"'
LWL ^rr
i- Intake valve
^ vVetwell ••/•.
^ £ heating coil
N3
ii^'intake screen
(Not to scale)
-------
3-24
FIGURE 3-10. WATER SUPPLY UTILIDOR AT
COPPERMINE, NWT
A second benefit offered by the infiltration gallery is the
filtration of the water by the materials surrounding the collectors.
This may be a very significant advantage in streams which carry a load of
suspended material such as silt or glacial rock flour.
Infiltration galleries may be constructed parallel to the water
course, across the water course, vertically, or radially. Schematics of
such systems are shown in Figure 3-11.
Galleries must be protected against freezing, especially in perma-
frost areas. Some sort of heating system is usually installed during con-
struction. Both electric and steam heating systems have been
successfully used. Usually steam lines are placed on the upper surface
of the lateral and a second steam line is installed 0.4 to 0.6 metres
above the lateral.
Insulation with snow is another way to reduce frost penetration
However, to be effective, the area should receive no traffic in order to
preserve the uncompacted snow cover [7],
Periodic gallery cleaning may be necessary to remove silt and
other sediments which enter the laterals and sumps. The use of modern
filter fabrics may reduce this requirement and improve overall system
performance.
-------
Pumphouse ]
Horizontal gallery
Horizontal gallery
Water stratum
Radial gallery
Water stratum
Gravel packed ditch
Vertical gallery
to
Ln
French drain
FIGURE 3-11. INFILTRATION GALLERIES
-------
3-26
Springs can be developed by installing horizontal infiltration
galleries in the aquifer. This is a generally approved method since it
reduces the possibility of water contamination at the point of collec-
tion.
3.4.3 Wells
A producing well is most successfully located through detailed
examination of geologic conditons: kinds and permeabilities of soils and
rocks; position of layers; character of cracks, fissures and other large
openings; and a study of performance records of other wells in the area
[8]. Especially in arctic regions, professional hydrogeologists familiar
with permafrost should be consulted during the preliminary stages when
considering groundwater as water supply source.
In all cases, wells must be located a safe distance from
potential sources of pollution. Local health departments usually have
specific requirements but in the absence of other guides, wells should be
at least 60 m from the nearest source of pollution.
3.4.3.1 Well drilling. There are several opinions on the best method
for drilling water wells. Locations, accessibility, size of well required
and other such factors will influence the methods used. The U.S. Public
Health Service, Indian Health Service, Office of Environmental Health
believes that because of equipment transportability, cable tool drilling
is superior in remote areas. "Jetting" of smaller wells has the advantage
of relatively low cost and the machinery is easier to move into remote
areas. Cable tool systems require less water for the drilling operation
than the jetting method, although most water used in drilling can be
reused.
Jetting combines hydraulic action and thawing, relying upon the
volume of water rather than high pressure to "drill" the well. A stream
of water is directed down into the ground, gradually thawing the soil
which is washed away in the water. Water may be reused repeatedly by
recirculating through a settling basin to remove cuttings. Jetting is
best suited to frozen soils which are primarily sand, silt, clay, or a
combination of these. The system is not effective in regions where there
are large rocks or layers of rock to be penetrated.
-------
3-27
Cable tool drilling uses the weight of a "string" of drilling
tools to penetrate through all varieties of soil and rock. Progress may
be from 1.5 m to more than 30 m per day, depending upon geologic condi-
tions. Tools are lifted, dropped and turned regularly; this pulverizes
the soil or rock and allows it to be suspended and carried away by a
minimal amount of water and a bailer. In hard formations, no casing is
required until the well is completed. However, in sand, silt or clay (or
organic) soils the string of tools is operated inside the well casing.
The casing is usually driven into the ground and then the well drilled
inside. This procedure is repeated in a leap-frog manner until a water-
bearing stratum is penetrated.
Rotary drilling machinery may also be used in all types of
geological formations, but involves considerable expense for equipment,
and reasonable degree of operational experience and skill. Whereas
jetting and cable tool drilling equipment may be "broken down" for
transport in light aircraft, rotary drills are not as small nor as easily
moved to remote locations. Rotary drills are, in general, much faster
than other means of drilling. As with cable tool drilling, a small
amount of water is used with the rotary drill. A special Bentonite
"drilling mud" pumped down through the drill stem and out through ports
in the drill bit and subsequently to the surface carries away the
cuttings. The drilling mud coats the sides of the hole and protects it
from scouring action of the water. Drilling mud is used over and over
during the drilling operation after the cuttings have been removed.
In some instances it may be necessary to heat the drilling fluid
during the operation, such as when drilling through frozen soil under
winter conditions. The heated fluid prevents the mud from freezing in
the permafrost and aids in thawing as the drill penetrates.
Air rotary drilling is a variation of rotary drilling which
employs pneumatic rather than hydraulic action to carry cuttings away
from the drill.
3.4.3.2 Well seals. Sanitary well seals on top of well casings will
prevent contamination by surface sources and still permit easy removal of
the pump when necessary. If pumps and pipes to the building can be
-------
3-28
installed below the seasonal frost line, a single pipe from the well will
suffice. However, if the well is installed in permafrost or pipes cannot
be installed below seasonal frost, some method will be required to prevent
freezing of the well. One such system is illustrated in Figure 3-12.
The use of Bentonite grout instead of cement provides an adequate seal
and reduces the possibility of frost heave damage to the well casing.
3.4.4 Pumping stations
Pumphouses can provide shelter for pumping equipment controls,
boilers, treatment equipment and maintenance personnel who must operate
and service the facility. Structural design will depend on the require-
ments of each location and must be considered individually. Equipment
housed within the shelter will also depend on the individual system and
may vary from a simple pump to a complex system with boilers for heat
addition, standby power, alarm systems to alert operators of malfunction
and the like. Any system must provide the degree of redundancy and
safeguards required by the nature of the operation and location. Figure
3-13 shows the pumphouse at Rankin Inlet, Northwest Territories.
More elaborate pumphouses will include redundant pumps, standby
power sources and alarm systems to alert the operator in the event of
failure. Voltage control devices are recommended to protect electrical
equipment where power is of questionable consistency or dependability
(see Figure 3-14).
All pumphouses should be designed with moisture-proof floors since
water will be on the floors frequently. Pumphouses in cold regions must be
large enough to accommodate additional equipment such as heaters and their
controls. Oversizing the original pumphouse at an installation should be
considered carefully in relation to design life and the accuracy of
demand predictions.
Heat addition at the source is usually desirable since the water
will be very cold, often approaching 0°C. Protection from freezing,
then, is the overriding reason for heating water at the source, although
there are also difficulties associated with treatment of very cold waters.
Enough heat must be added to at least compensate for heat lost in trans-
mission. It is generally accepted that water in transmission lines should
-------
3-29
Jet pump pitless adapter (altered)
Machined out area
between the two
passage ways in adapter
25 Plug
Air inlet to allow water
to drain out of drop pipe
to submersible pump
FROST PENETRATION
0.5°C Water from submersible pump
Sanitary well seal
25 Pump lift pipe
100 Casing
• Frost heave protection where necessary
Electric wire for submersible pump
25 Hot water from pumphouse (4.5°C)
40 Mixed hot and cold water from well (3.5°C) —
40 Check valve to prevent hot
water from going into well when
submersible pump is not operating
40 W.I. Pipe
Allow for movement around
the connection (insulation, etc.)
FIGURE 3-12. WELL SEAL
-------
3-30
FIGURE 3-13. PUMPHOUSE AT WILLIAMSON LAKE
AT RANKIN INLET, NWT
Vent
Chlorine tank
Vertical turbine deep well pumps
360° Swing beam crane
Fixed beam
Future pump installation
\
Chlormator
Indicating, recording
and control
FIGURE 3-14. PUMP STATION
-------
3-31
be at least 4°C to provide an adequate margin for heat loss in the event
of a pump failure.
3.4.5 Transmission lines
Pipelines carrying water from the intake and pumphouse to the
storage reservoir may be either buried or laid above-ground, depending
upon local conditions. In general, buried lines are preferred to reduce
maintenance and heat loss. Surface or elevated lines must have additional
insulation and should be protected from climatic and physical abuse which
is likely to occur. All pipelines should be provided with some form of
heat tracing or thawing method. More detailed design information is
covered in Sections 6 and 15.
Pumps and transmission lines should be provided with drains,
preferably automatic, to evacuate the water in case of power loss or
other long-term failure, and thus prevent rupture due to freezing. These
essential provisions may be as simple as the elimination of check valves
and providing positive gradient.
3.5 References
1. Slaughter, C.W., Mellor, M., Sellmann, P.V., Brown, J., and Brown, L.
"Accumulating Snow to Augment the Fresh Water Supply at Barrow,
Alaska". U.S. Army, Cold Regions Research and Engineering
Laboratory. Special Report 217, Hanover, New Hampshire, January,
1975.
2. McFadden T., and C. Collins, "Case Study of a Water Supply for Coastal
Villages Surrounded by Salt Water", Cold Regions Specialty Conference,
17-19 May, 1978, Anchorage, Alaska, American Society of Civil
Engineers, New York, N.Y., 1978.
3. Smith, M.W. and C.T. Hwang, "Thermal Disturbance due to Channel Shifting,
Mackenzie Delta, N.W.T, Canada" In: North American Contribution to
Permafrost Second International Conference, 13-28 July, 1973,
Yakutsk, U.S.S.R., National Academy of Science, Washington, D.C.,
pp. 51-60, 1973.
4. Alter, A.J. "Water Supply in Cold Regions". Cold Regions Science and
Engineering Monograph III-CS2. U.S. Army, Cold Regions Research
and Engineering Laboratory. Hanover, New Hampshire, January, 1969.
-------
3-32
5. Reed, S.C. "Water Supply in Arctic Regions". New England Waterworks
Association. Vol. 84 (4), December, 1970.
6. U.S. DREW. Public Health Service. "Manual for Evaluating Public
Water Supplies", PHS Pub. No. 1820, Washington, D.C., January, 1969.
7. Feulner, A. J. "Galleries and Their Use for Development of Shallow
Ground Water Supplies with Special Reference to Alaska". U.S.
Geological Survey Water Supply Paper 1809-E, Washington, D.C., January,
1964.
8. Longwell, C.R. and Flint R.F. Physical Geology. John Wiley & Sons,
New York, 1955.
3.6 Bibliography
Alter, A.J. "Arctic Environmental Health Problems". CRC Critical
Reviews in Environmental Control, Vol. 2, pp. 459-515. January, 1972.
Babbitt, H.E., Doland, J. James and Cleasby, John L. Water Supply
Engineering. McGraw-Hill, 1962.
Campbell, Michael D. Water Well Technology. McGraw-Hill, New York, 1973.
Dickens, H.B. "Water Supply and Sewage Disposal in Permafrost Areas
of Northern Canada". Polar Record. Vol. 9, p. 421, 1959.
Eaton, E.R. "Thawing of Wells in Frozen Ground by Electrical Means".
Water and Sewage Works, Vol. Ill (8), August, 1964.
Foulds, D.M. and Wigle T.E., "Frazile-the Invisible Strangler".
Journal AWWA. Vol. 69, No. 4, p. 196, April, 1977.
Gordon, R.C. "Winter Survival of Fecal Indicator Bacteria in a
Subarctic Alaskan River". U.S. Environmental Protection Agency
Report EPA-R2-72-013, Washington, D.C., 1972.
Heinke, G.W. "Sanitation for Small Northern Communities: Some
Problems and Goals". Canadian Journal of Public Health, Vol. 62,
1971.
Hostrup, Lyons and Assoc. "Study of the Mechanical Engineering
Features of Polar Water Supply". U.S. Naval Civil Engineering
Research Lab. Contract No. y 27491. August, 1953.
Karr, W.V. "Groundwater, Methods of Extraction and Construction".
International Underground Water Institute. 1969.
McKee, Jack Edward and Wolf, Harold W., "Water Quality Criteria".
The Resources Agency of California. Publication #3-A, Sacramento, 1963.
-------
3-33
Page W.B., Hubbs G.L., Eaton E.R., "Report on Procedure for Jetting
Wells". Arctic Health Research Centre, Fairbanks, Alaska, May, 1958.
Rice, E.F. and Alter A.J., "Water Supply in the North". The Northern
Engineer. Vol. 6 (2), 1974.
U.S. Arctic Health Research Centre, "Technical Information on Water
Supply Management for North Slope Activities". Report No. 106,
Fairbanks, Alaska, 1970.
U.S. Department of the Navy, Naval Facilities Engineering Command.
"Cold Regions Engineering Design Manual", NAVFAC DM-9. Alexandria, Va.,
March, 1975.
-------
SECTION 4
WATER TREATMENT
Index
Page
4 WATER TREATMENT 4-1
4.1 General 4-1
4.2 Process Design 4-1
4.2.1 Heat addition 4-2
4.2.2 Coagulation and flocculation 4-4
4.2.3 Sedimentation 4-6
4.2.4 Filtration 4-6
4.2.5 Adsorption 4-8
4.2.6 Disinfection 4-8
4.2.7 Fluoridation 4-9
4.2.8 Water softening 4-10
4.2.9 Iron removal 4-10
4.2.10 Colour removal 4-11
4.2.11 Organics removal 4-11
4.2.12 Desalination 4-12
4.2.13 Ozonation 4-13
4.3 Plant Design 4-14
4.3.1 Buildings 4-14
4.3.2 Ventilation 4-15
4.3.3 Lighting 4-15
4.3.4 Controls 4-16
4.3.5 Standby equipment 4-16
4.3.6 Miscellaneous considerations 4-16
4.4 Reference 4-17
4.5 Bibliography 4-17
-------
List of Figures
Figure Page
4-1 Dissolved Oxygen Saturation Variation with Temperature 4-2
4-2 Viscosity of Water at Atmospheric Pressure 4-5
4-3 Viscosity Effects versus Temperature 4-5
4-4 Settling Detention Time versus Temperature 4-7
4-5 Building Partially Insulated with Earth Banks 4-15
List of Tables
Table Page
4-1 Upflow Clarifier Loading Rates 4-7
4-2 Fluoridation Requirements 4-9
-------
4-1
4 WATER TREATMENT
4.1 General
The objectives of water treatment in cold regions are identical
to those in other areas - to provide high quality potable water to
improve and sustain health and eliminate the spread of waterborne
disease.
Under most conditions the treatment methods used in cold regions
are the same as those in temperate climates. However, temperature has a
significant effect on many processes in water and wastewater treatment,
sometimes requiring adjustment In design and operation.
Water is susceptible to a change of state at temperatures of
0°C or less unless properly protected. When means of replenishing
lost heat fail, freezing may occur even when pipes and tanks have been
insulated. For this reason and because treatment is simplified when
water is relatively warm (> 5°C), it is common practice in cold
regions to add heat to water prior to or as a part of the treatment
process.
Cold climate conditions require that special attention be given
to certain aspects of treatment plants and processes. Although these
considerations sometimes seem trivial, failure to attend to them may
cause serious difficulty in achieving desired objectives.
Quality standards have been established for drinking water in
the United States and Canada. These standards are presented only as a
guide since provincial or state standards may be more restrictive.
4.2 Process Design
Standard water treatment processes may need to be modified when
they are applied to cold waters. An alternative to process modification
is the option of adding heat as a pretreatment operation; sometimes both
methods are used together.
Water treatment involves chemical, physical and biological pro-
cesses which are, to a greater or lesser extent, temperature sensitive.
"Cold water" is the term used to describe water in the temperature range
of 0°C to about 5<>c. Exact definition of the range is not intended
nor is it required since changes are continuous with temperature.
-------
4-2
4.2.1
Heat addition
Heat addition is often practiced to protect the distribution
system. When heat is added prior to treatment, other benefits accrue.
Also, as an alternative to modifying unit process designs to compensate
for low temperature, the designer may choose to add heat to the water as
a preliminary treatment step. The annual temperature variation for
surface waters in cold regions varies from 0°C to about 20°C. By
adding heat during the period when the water is cold, other treatment
processes may be used essentially unmodified. Higher sedimentation and
filtration rates and reduced mixing times result, and overall plant
requirements for space and energy are reduced. Moreover, pumping
requirements for warm water are lower than for cold water.
4.2.1.1 Corrosion control. Cold water can absorb more oxygen than
warm water. Figure 4-1 shows the variation of oxygen saturation with
temperature. As water is warmed, oxygen is released. This oxygen causes
iron and steel pipes, pumps and tanks to rust. By controlling the region
in which oxygen is released, corrosion within the treatment plant and the
distribution system may be reduced.
16
O)
c
g
2
i5
-i—1
CO
co
CD
O)
X
O
CD 4
8
0
0
4 8 12
Temperature (°C)
16
20
FIGURE 4-1. DISSOLVED OXYGEN SATURATION VARIATION WITH TEMPERATURE.
-------
4-3
4.2.1.2 Standardization. Virtually all "package" type treatment systems
are designed for use with water warmer than about 5°C. If incoming
water is expected to be colder, heat must be added for the system to
perform properly at design rates. This allows the use of standard design
in areas of varying water temperature.
4.2.1.3 Method of heating. Several methods of heating water may be
used for equally satisfactory results. It should be remembered that
purity of drinking water is extremely important and any possibility of
contamination must be avoided.
Direct fired boiler. This system uses a direct-fired oil, gas
or coal furnace operated so that the water is maintained below boiling,
usually at about 90°C. Three basic types of boilers are 1) water
tube, 2) fire tube, and 3) cast iron water jacket. The boiler must be
operated in a manner which prevents cooling exhaust gases below the dew
point. Cold water may reduce exhaust gas temperature significantly and
if condensation occurs corrosion will reduce boiler and chimney life.
Thermal efficiency is optimized when the boiler is operated at the lowest
temperature possible without causing condensation of exhaust gases.
Liquid-liquid heat exchangers. This system employs a closed
vessel containing a series of tubes. An inlet and an outlet manifold are
provided for both the jacket and the tube bundle. Usually the hot liquid
is circulated through the jacket and the liquid to be heated is
circulated through the tubes.
The source of heat for this system may be a building or city
central heating system or the cooling water from an engine, or any other
suitable source. Antifreeze may be used in the hot fluid but caution
must be exercised because of the possibility of tube leak and cross-
connection.
Blending. Occasionally a source of hot water is available which
can be blended with cold water to achieve the desired temperature. Such
a source may be condenser water from a steam system. Fairbanks, Alaska,
successfully employed this system of warming cold well water. In
Whitehorse, Yukon Territory, geothermal water is added to raw water and
provides a very substantial saving.
-------
4-4
4.2.2 Coagulation and flocculation
Coagulation is a chemical process involving the destablization
of colloids. It is slightly temperature-sensitive in the range from
0°C to 30°C. Flocculation is the aggregation of destabilized
colloidal particles to a size adequate for subsequent settling by gentle
mixing of the fluid in which the colloids are contained. The inter-
particle contacts necessary for flocculation are influenced by fluid
viscosity. Figure 4-2 shows viscosity is inversely related to
temperature.
4.2.2.1 Mixing. Mixing is an important function in water treatment
since it is required for flocculation and the dissolving of solids in
liquids. Mixing is strongly dependent on temperature because of changes
in the viscosity of the liquid. Figure 4-3 can be used to make the
necessary adjustments in design criteria for temperature-induced viscosity
changes. It is plotted with 20°C as the base level. The power input
for mechanical flocculation is directly dependent on fluid viscosity, as
defined by:
P = G2Vp (4-1)
where: P = power input (kW),
i-\
G = velocity gradient (m/s/m),
V = tank volume (m ),
U = absolute fluid viscosity (Pa/s).
To maintain the same velocity gradient in the tank as the
liquid temperature decreases, it is necessary to adjust the 20°C
power requirement by the multiplier from Figure 4-3. This relationship
will be valid for any type of mechanical mixing.
Detention time required for mixing is determined separately. It
is influenced by the time required for desired reactions to occur and is
often arbitrarily based on successful performance of similar units.
Recommended detention times for flocculation of water range from 15 to 30
minutes. Increasing this detention time will compensate for lower water
temperatures. The multipliers from Figure 4-3 can also be used for this
purpose. Multiple basins in series are the most effective way to increase
detention time, provided some basins can be bypassed during warm weather.
-------
4-5
1.0 1.1 1.2 1.3 1.4 1.5
Absolute viscosity (centipoises)
1.6
0
1.7 1.8
O
o
CD
:5
03
o>
Q.
E
CD
FIGURE 4-2. VISCOSITY OF WATER AT ATMOSPHERIC PRESSURE
Q_
"5
1.75
1.50
1.25
Multiplier = 1.82 e°03T
1.00L
o.oof
10 15
Temperature (°C)
J L
3
20
FIGURE 4-3. VISCOSITY EFFECTS VERSUS TEMPERATURE
-------
4-6
One alternative to extended mixing time is the use of higher
chemical dosage. Another is to adjust pH to the optimum for the
temperature of the water being treated. Optimum pH varies inversely with
water temperature. It is advisable to evaluate each alternative since
one may be more economical.
4.2.3 Sedimentation
Settling of particulate materials is retarded by increased
viscosity in cold waters. The settling velocity of particles is
proportional to the temperature as shown in Figure 4-4. Increased
clarifier size is recommended where cold water is to be treated.
Upflow clarifiers. Upflow and sludge blanket clarifiers are not
as sensitive to low temperature as conventional clarifiers. However,
temperature variations may cause thermal currents which can easily break
through the sludge blanket and ruin efficiency. Sludge blanket and
upflow clarifiers should be operated at nearly constant temperatures.
Table 4-1 presents some recommended loading rates for upflow clarifiers
which employ tube modules.
4.2.4 Filtration
Filtration is affected by low water temperature to the extent
that head losses through the filter are proportional to viscosity. The
relative head loss changes about 3.5% per degree Celsius temperature
o •}
change. Normal sand filter loading rates are about 5 mj/m «h
O r\
and mixed media filter loadings are about 12 m /m »h. Therefore,
multi-media filter beds would provide more efficient use of space in cold
climate facilities. The multiplier values from Figure 4-3 should be used
to reduce filtration efficiency. For example, if the initial design head
loss is 1 m at 20°C it will be about 1.5 m at 5°C.
Backwashing of filters is also affected. Power for pumping will
vary as shown on Figure 4-2. Adjustments for filtration and backwashing
are based on viscosity changes. However, the minimum upflow velocities
or wash rates to fluidize and clean filter media will be reduced because
of increased fluid density. For example, if it takes a velocity of 0.09
cm/s to fluidize a sand bed at 20°C it will only require 0.06 cm/s at
5°C.
-------
4-7
2.00
1.75
jj 1.50
Q.
1.25
0.75
0
0
35
40
Temperature (°F)
45 50 55
60
65
10
15
20
FIGURE 4-4,
Temperature (°C)
SETTLING DETENTION TIME VERSUS TEMPERATURE
TABLE 4-1. UPFLOW CLARIFIER LOADING RATES
Overflow rate based on total
clarifier area and temp, less
than 4°C.
Overflow rate based on area of
clarifier covered with tubes.
Temperature less than 4°C.
3, 2 , 2
m /m h gpm/ft
6.1
8.6
2.5
2.5
Overflow rate based on total
clarifier area and temp.
greater than 10°C.
3, 2 ,
m /m h
3.7
4.9
2
gpm/ft
1.5
2.0
3,2,
m /m h
4.9
6.1
2
gpm/ft
2.0
2.5
Overflow rate based on area of
clarifier covered with tubes.
Temperature greater than 10°C.
3.2 ,2
m /m h gpm/ft
4.9
7.3
2.0
3.0
-------
4-8
4.2.5 Adsorption
Adsorption is an exothermic process and in the range of 0°C
to 20°C is essentially unaffected by temperature change [1,2].
4.2.6 Disinfection
Disinfection is the process of destroying or inactivating
disease-causing organisms in the water. Traditionally, disinfection has
been directed toward reduction of bacteria and is probably not as
effective in destroying either viruses or cysts.
4.2.6.1 Chlorine. Chlorine has been almost universally used as a
disinfectant for potable waters throughout this century. The greatest
advantages are the ability to maintain and measure residuals, low cost
and economy of use. Also, the availability of chlorine as G-2 gas,
calcium hypochlorite Ca(OCl)2 and sodium hypochlorite (NaOCl) make it
possible to safely handle the disinfectant under a variety of conditions.
Logistics and operator qualifications should guide the designer in
selecting the chlorine source.
Solubility of chlorine is theoretically a factor in cold water.
However, chlorine is virtually never dosed at rates which are insoluble
in water in the normal range of temperatures.
In recent years there has been significant concern over the
byproducts created by using chlorine as a disinfectant in waters contain-
ing organic compounds. It has been discovered that some organic
compounds form carcinogenic substances when exposed to chlorine in water.
As a result there is a growing trend away from pre-chlorination in the
production of potable water.
Chlorine disinfection is hindered by cold water. Exposure time
must be increased as water temperature decreases. Contact time of at
least one hour is recommended and residuals must be maintained throughout
the contact period to achieve the desired bacteriacidal effects.
4.2.6.2 Halogens. Aside from chlorine, two other members of the
halogen group have been used as potable water disinfectants. These
elements are iodine and bromine. Both substances have been tentatively
approved but their use has been primarily supplemental to chlorine in
swimming pools with only occasional use as potable water disinfectants.
-------
4-9
Costs for iodine and bromine cannot compete with gaseous chlorine (about
25 to 1); however, iodine may be competitive with some forms of hypochlo-
rite.
Iodine has the advantage over chlorine of producing minimal
tastes and odours in the presence of phenols. Also, iodine can be stored
in non-metallic containers for extended periods without appreciable loss
or deterioration.
4.2.6.3 Ozone. Next to elemental fluorine, ozone is the strongest
oxidizer known and as such it is an excellent disinfectant. Ozone also
has other possible uses which are discussed in Section 4.2.13.
Ozone is only slightly temperature sensitive so no appreciable
modification of standard technique is required. However, ozonation
equipment is expensive to install and operate. Where cost is less
important than logistic consideration, ozone has the advantage of being
generated from air using electricity and is unaffected by resupply
problems in remote areas.
4.2.7 Fluoridation
Fluoridation of potable water in cold climates requires a higher
dosage because per capita consumption of drinking water tends to be
somewhat less than in temperate regions. Normally, fluoride concentra-
tion should be about 1.4 mg/L in cold regions. Table 4-2 lists the
recommended ranges of fluoride in drinking water at various annual
average air temperatures.
TABLE 4-2. FLUORIDATION REQUIREMENTS
Annual average of maximum
Recommended control limits
Fluoride concentrations in mg/L
daily air temperature*
°C
12 and below
12.1 to 14.6
14.7 to 17.6
17.7 to 21.4
21.5 to 26.6
26.7 to 32.5
Lower
0.9
0.8
0.8
0.7
0.7
0.6
Optimum
1.4
1.1
1.0
0.9
0.8
0.7
Upper
2.4
2.2
2.0
1.8
1.6
1.4
Based on temperature data for at least five years.
-------
4-10
4.2.8 Water softening
Water softening is often required in cold climates where
groundwater frequently contains high concentrations of calcium and/or
magnesium hardness. Two methods of softening are well developed: ion
exchange and chemical precipitation.
4.2.8.1 Ion exchange. Ion exchange water softening is affected by low
water temperature to the extent that it is essentially a filter-type
system and flow is viscosity dependent.
Waters derived from subpermafrost aquifers tend to be slightly
deficient in oxygen and as a result may contain relatively large amounts
of soluble forms of iron. Iron can foul zeolite and greensand ion exchange
resins and must be removed prior to softening. (See Section 4.2.9).
4.2.8.2 Chemical precipitation. Lime-soda softening is frequently
used where water to be treated is turbid and requires clarification.
This process is affected by low water temperature since it involves
mixing, f]occulation, sedimentation, filtration and sludge handling.
4.2.9 Iron removal
Iron is of considerable concern in waters in cold climate areas.
Iron is one of the most abundant elements in nature and its presence in
varying amounts is to be expected. It may exist in any of nine valence
states but Fe+^ and Fe -* are most important in water. In addition
to elemental iron, organic iron complexes present problems.
Limiting iron in water supplies is more for aesthetic purposes
than for health reasons. Canadian Drinking Water Standards and
Objectives and the U.S. National Secondary Standards for drinking water
limit iron to 0.3 mg/L.
High iron concentrations in cold climate waters may be explained
as follows. Groundwaters and waters beneath the ice in ponds and shallow
lakes are deficient in dissolved oxygen. As the water dissolves iron it
is oxidized to FeOH+, which is a highly soluble form. In surface
waters where there is sufficient dissolved oxygen, much less soluble
Fe(OH)3 and Fe2C>3 are formed.
Treatment of waters containing iron requires oxidation, which may
be accomplished by aeration or by chemical oxidation with chlorine or ozone,
Simple aeration is not effective for removing iron/organic complexes.
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4-11
Low temperatures restrict the aeration process. Although oxygen
is more soluble at low temperatures, overall gas transfer is lower. This
is explained on the basis of viscosity, gas/liquid contact etc.
Furthermore, the type of aeration system influences gas transfer rates.
Compressed air systems are more efficient than mechanical surface-type
aerators. Oxygen transfer coefficients have been evaluated over the
temperature range from 3°C to 35°C with the following results:
/•p — rj> N
- for compressed air system = 1.024 0 2
ff •*— T ")
- for mechanical aerators = 1.016 0 2
Coarse bubble diffusers tend to be more maintenance-free than
other types of aerators. Aeration can be accomplished by cascade or
"waterfall" systems, but these tend to be associated with humidity
problems in the treatment plant.
Aeration tanks should have a width to depth ratio of 2 to 1 or
greater to promote good mixing. Detention time will be on the order of
10 to 30 minutes and the air volume range required will be 0.05 to 1.25
m3 per m3 water treated.
4.2.10 Colour removal
Objectionable colour concentrations are frequently found in
water originating in tundra regions where organics are leached from
decaying vegetable matter. Colour may be reduced or removed by chemical
oxidation with chlorine or ozone and with carbon adsorption.
4.2.11 Organics removal
Organic materials in water, much like colour, are removed to a
limited extent by coagulation and sedimentation. More complete removal
requires carbon adsorption or ozone treatment.
Activated carbon Ls effective for removal of organics but when
granular carbon is used, there is a strong potential for enhancing
bacterial growth in the carbon bed. Organics removed from the water
become food for micororganisms which may eventually be washed through the
carbon bed and into the product water. Post disinfection is required in
this situation.
Joint use of ozone and carbon adsorption has been found extremely
effective in organics removal and for treating iron-organic complexes.
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4-12
Ozone destroys microorganisms and breaks down many organics. The remain-
ing organics are absorbed on the carbon beds.
4.2.12 Desalination
In coastal areas of the Arctic and in some areas where ground-
water sources are highly mineralized, desalination may be required.
Several desalination methods are available including distillation,
reverse osmosis (RO) and freeze treatment.
4.2.12.1 Distillation. Distillation is the best known, most highly
developed means of removing dissolved materials concentrations from
water. Cold water increases the operational costs of distillation
slightly. The relatively high skill requirement for operators makes this
o
an undesirable process in remote areas. Small stills (about 20 m /h)
require about 1 kg of diesel fuel for 175 kg product.
4.2.12.2 Reverse osmosis. Reverse osmosis (RO) uses mechanical energy
to drive water through a semipermeable membrane. By proper membrane
selection water may be produced which is quite acceptable for potable
purposes. RO is temperature sensitive with the best results obtained
when water temperatures are in the range of 20°C to 30°C.
The cost of RO is relatively high due to equipment operation and
maintenance requirements. Small RO units are available in sizes from 3.5
m-Vday to 3500 m^/day. These units require about 2.4 kWh of power
for each cubic metre of water treated. The cost/benefit ratio for RO
desalination is improved by the following factors:
1) higher water temperatures,
2) industrial/commercial water users,
3) sewers for brine disposal.
Reduction of the cost/benefit ratio is caused by the following:
/
1) high land costs,
2) high electrical power costs,
3) high population density per dwelling unit,
4) high interest costs.
-------
4-13
Actual costs for RO in the United States ranged from 11 cents
per cubic metre of water for a town of 63,000 people to 55 cents per
cubic metre for a town of 1250 people.
RO treatment systems must be protected from freezing at all
times. Membranes which have been frozen are unreliable even if freezing
has occurred during shipping prior to installation.
4.2.12.3 Freezing. Treatment by freezing is a system which may be
practical in cold regions where the cold may be used as a resource. This
method is based upon the fact that as water freezes, impurities are
slowly "refined" or "salted out" and the ice contains only pure water.
Three types of freezing processes have been used successfully in pilot
projects.
The reservoir process involves freezing a large volume of water.
When ice containing the desired volume of water has been formed, the
brine below the ice is withdrawn. When the ice is melted, purified water
is the product.
Layer freezing involves a more complex system of freezing
brackish water in successive sheets. The first water melted off in warm
weather is wasted because it contains most of the impurities.
Spray freezing involves spraying brackish water through a modified
lawn sprinkler to form a cone of ice. Pure water is frozen most quickly
and brine drains away continuously throughout the winter. In a pilot
scale test in Saskatchewan, chloride content was reduced from 2000 mg/L
to 500 mg/L for 75% of the brackish water sprayed [3], Estimated total
costs for the process were about 22 cents per cubic metre of product.
4.2.13 Ozonation
Ozone as a disinfectant was briefly covered in Section 4.2.6.3.
However, European experience with ozone in water treatment for many years
has shown numerous benefits in addition to disinfection.
Iron and manganese are effectively removed by oxidation with
ozone followed by separation. Applied early in the treatment chain,
ozone rapidly oxidizes iron and manganese and aids in flocculation.
* 1977 U.S. dollars.
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4-14
Organics oxidation by ozone is accomplished by ozone addition in
the middle of the overall process. Followed by granular activated
carbon, this is very effective in removing organics and has none of the
side effects of taste and odour associated with chlorination.
Ozone systems are expensive to build. Costs for a system produc-
ing less than 450 kg/d (0^) are approximately $2200 per kg of daily
ozone production. Operational cost, including amortization over 20
years, ranges from 1/2 cent per cubic metre to 1 cent per cubic metre of
water treated.
4.3 Plant Design
There are several aspects of water treatment plant design in
cold regions which are important. Nearly all functions of water treat-
ment must be housed for process protection as well as for ease of
maintenance and operation of equipment. Certain unit processes require
heated shelter, while others require shelter only. Generally, processes
which include equipment such as pumps and exposed piping must be housed
and heated to prevent damage from freezing. Water temperature, not air
temperature, determines process efficiency.
4.3.1 Buildings
Combining different functions under one roof rather than in a
group of smaller buildings reduces surface area and heating requirements.
Piping and electrical runs may be shorter and less expensive initially
and possibly easier to maintain. Possible expansion in the future should
be considered in selecting the single building concept. The floor plan
of cold region systems can be critical to building efficiency. Designers
should place areas which require stable heat in the building interior,
and store rooms and other less vital functions against outer walls. In
this manner, heat lost from the interior is used to heat other space
before escaping outdoors. Building shape can be optimized to reduce
surface area and oriented to take advantage of sunshine.
Placement of some functions below ground and banking buildings
with earth on outside walls will reduce energy requirements (See Figure
4-5).
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4-15
Fan forced ventilation
•Controls
Process area
FIGURE 4-5. BUILDING PARTIALLY INSULATED WITH EARTH BANKS
Vapour barriers are very important in cold climates and more
so in buildings where moist air is prevalent such as in treatment plants.
Poor vapour barriers will permit moisture to penetrate into wall and roof
insulation and reduce its effectiveness.
4.3.2
Ventilation
Ventilation is important both for human health and comfort and
building economy. Moist indoor air in process areas must be expelled to
prevent condensation and related problems. Air may be reused from one
type of space to another to economize on the amount of warm-up required.
For example, air may be moved from office space to lab space before
exhaust, or from office to process areas. If dehumidification equipment
is installed, process space air might be reused in either office or lab
space.
An alternative to this direct reuse of air is to extract heat
from warm, moist exhaust air to preheat incoming fresh air. Several
fairly efficient devices are available to perform this function.
Continuous ventilation may not be necessary in all spaces. When
offices and labs are not occupied it is unnecessary to force ventilate
them and waste heat.
4.3.3 Lighting
Adequate lighting is important both inside and outside treatment
plants; in cold northern climates it is particularly essential because of
reduced wintertime daylight. Controls for lighting circuits should be
designed so that minimum light is provided in unoccupied areas with
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4-16
supplementary lights available as needed. Unless relatively small light-
ing circuits are provided, appreciable power may be lost to a function
not actually needed.
4.3.4 Controls
Process controls are sensitive devices which may be adversely
affected by low temperature or high humidity. Plant design should
provide controls on interior walls or in special cabinets away from the
influence of moisture and temperature. Ventilation should be provided to
reduce the possibility of damage by atmospheric changes.
4.3.5 Standby equipment
In cold regions equipment is subjected to rigorous conditions.
As a result, equipment failure may be more frequent. Providing redundant
equipment may increase system reliability.
It is recommended that the designer not place total reliance on
^
one item if that reliance could as easily be placed on two smaller items.
For example, rather than one large pump, two or three smaller ones will
generally be more desirable. This also permits periodic maintenance
without suspending operation entirely.
4.3.6 Miscellaneous considerations
4.3.6.1 Drainage. Whenever possible, plants should be designed and
built so that they can be drained by gravity if necessary. This is
particularly true in remote areas and at smaller installations.
4.3.6.2 Auxiliary power. Auxiliary power supply should be provided to
support minimum operation of the treatment plant and distribution system.
4.3.6.3 Space/process trade-offs. Under some circumstances the designer
may wish to evaluate the overall benefits of energy-intensive processes
which are space-efficient. For example, pressure filters or pre-coat
filters which require pumping may have overall advantages compared to
standard or mixed media gravity filters. Or in another case a centrifuge
may be preferable to a standard clarifier.
In cold climates these trade-offs must be evaluated carefully
because heating requirements are significant. Where plant expansion is
contemplated, these considerations may be particularly valuable by
allowing addition of capacity within existing space.
-------
4-17
4.3.6.4 Replacement parts. Plant management should maintain a stock of
replacement parts for equipment subject to failure or wear. This is
particularly important in remote areas where much time may be lost in
shipment of parts from sources of supply.
4.4 References
1. Magsood, R. and Benedek, A., "The Feasibility of the Physical-Chemical
Treatment of Sewage at Low Temperatures", IN Symp. on Wastewater
Treatment in Cold Climates, Saskatoon, Sask., Aug. 22-24, 1973,
E. Davis, ed., Environmental Protection Service, Environment
Canada, Report No. EPS 3-WP-74-3, pp. 523-548, Ottawa, 1974.
2. Magsood, R. and Benedek, A., "Low-temperature Organic Removal and
Denitrification in Activated carbon Columns", Jour. Water Poll.
Control Fed., 49(10):2107.
3. Spyker, J.W. and Husband W.H.W, "Desalination of Brackish Water by
Spray Freezing", Saskatchewan Research Council. EDC-73-CIV^,
1973.
4.5 Bibliography
Alter, Amos, J. "Water Supply in Cold Regions". U.S. Army Cold
Regions Research and Engineering Laboratory, Monograph III-C52,
January 1969.
Twort, A.C., Hoather R.C., Law P.M., Water Supply, second ed.,
American Elsevier Publishing Co., Inc., 1974.
Wallis, Craig, Staff, Charles H. and Melniok, Joseph L., "The Hazards
of Incorporating Charcoal Filters into Domestic Water Systems".
Water Research, Vol 8, pp. 111-113, 1974.
Weber, Walter J. Jr. Physiochemioal Processes for Water Quality
Control. John Wiley & Sons, Inc., 1972.
-------
SECTION 5
WATER STORAGE
Index
Page
5 WATER STORAGE 5-1
5.1 Purposes and Capacity Requirements 5-1
5.2 Tanks 5-2
5.2.1 General 5-2
5.2.2 Insulation 5-3
5.2.3 Design 5-8
5.2.4 Thermal considerations 5-9
5.2.5 Foundation 5-11
5.2.6 Costs 5-12
5.3 Earth Reservoirs 5-12
5.3.1 General 5-12
5.3.2 Water quality 5-12
5.3.3 Dams 5-14
5.3.4 Diked impoundments 5-14
5.3.5 Impervious liners 5-14
5.3.6 Foundations and thermal considerations in permafrost
areas 5-15
5.4 References 5-18
5.5 Bibliography 5-19
-------
List of Figures
Figure Page
5-1 Wood Tank with Insulation and Liner on Inside 5-4
5-2 Steel Tank with Board Insulation and Metal Cladding 5-4
5-3 Insulated Buried Concrete Tank 5-6
5-4 Above-Ground Concrete Tank, Greenland 5-6
5-5 Steel Tank with 75-mm Sprayed on Polyurethane
Insulation, Barrow, Alaska 5-7
5-6 Installation of an Impervious Liner in a Water Reservoir,
Eskimo Point, NWT 5-16
5-7 Liner Installation and Anchorage Embankments 5-16
List of Tables
Table Page
5-1 Water Storage Tank Costs 5-13
-------
5-1
5. WATER STORAGE
5.1 Purposes and Capacity Requirements
The total water storage requirement is the sum of flow equali-
zation, emergency and fire requirements. The reliability of the water
source and the community size, i.e., equipment and expertise available, will
influence the storage requirements. Typically, these will be two days total
water demand plus the fire requirements and any seasonal requirements.
Most piped and trucked water delivery systems will require some
storage capacity to meet daily and hourly water demand fluctuations.
This storage is called "buffer" or "equalization" capacity. Piped
systems in small communities typically have a peak hourly consumption of
4.5 times the average daily consumption (see Section 4). The storage
requirement for buffer capacity is generally one day's consumption.
Also, emergency storage of at least one day's water requirement should be
provided. Several days' supply may be necessary when the community is
served by a long pipeline. For trucked systems, storage of two days'
consumption within the community is desirable to breach any supply
interruptions, and to act as buffer capacity where a piped supply line
from the source is used.
Storage capacity is also required to act as a buffer and
to breach temporary supply failures where limited-yield wells or
constant-flow treatment plants are used.
Fire protection requirements for both piped and trucked systems
are outlined in Section 12. These requirements should be used to
calculate the storage capacity needed.
Water supply systems in some remote northern communities are
operational only on a seasonal basis. Where a continuous water supply
cannot be obtained, is too expensive, or is impractical to maintain,
enough water must be stored to supply the demand during periods of supply
failure. For example, where a temporary water intake system is utilized,
short-term storage is required to supply the demand when the intake is
inoperative during river or lake freeze-up and break-up. Complete winter
storage has been utilized at locations where all water sources cease,
freezeup, or are inaccessible during the winter. A water supply pipeline
from an inaccessible or distant water source may be used in the summer to
-------
5-2
fill a winter storage reservoir or tank. In these instances, the
duration of the expected source interruption and the design rate of
consumption will determine the storage capacity required. Local records
must be consulted.
5.2 Tanks
5.2.1 General
Special cold regions design considerations and problem areas
include: icing conditions; insulation; heat requirements; foundation design
(particularly in frost-susceptible soil); the difficulty and high cost of
carrying out maintenance in remote areas; and other eold climate construc-
tion and operation and maintenance (O&M) considerations such as transporta-
tion, labour, logistics, and weather (see Section 2). Tanks in cold regions
must be insulated and heat added to prevent ice formation in the tank.
Common storage tank construction materials are wood, steel and
concrete. Small individual tanks of aluminum, plastic and fibreglass
have also been used.
Wood tanks are particularly useful because they do not have to
be insulated. They are relatively light and the small pieces can be
easily shipped into remote areas. They can be erected by local people
without expensive, special equipment. Wood tanks can leak by sweating.
With very careful erection and regular maintenance, such as tightening of
bands, leakage can be reduced; however, this is not always easily
accomplished in northern utility systems. Any leakage during the winter
will result in icing on the outer surface. This ice buildup is a
nuisance and can result in damage to the tank and foundation. Unlined
tanks should be operated with as little water level fluctuation as
practical since the wood shrinks when it drys out, producing cracks.
Unlined wood tanks must be allowed to sweat; therefore, they must not be
painted or coated. Leakage problems can be overcome by installing a
flexible waterproof liner inside the tank. The liner material must be
rugged enough to withstand shipping and installation handling, and may
require low temperature specifications (see section 5.3.5). Wherever
possible, the liner should be prefabricated, with the necessary openings
reinforced, and in one piece, to reduce the amount of field work and
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5-3
allow complete replacement. It is imperative to prevent ice formation
within the tank because this will damage the liner and punctures are
difficult to locate. This is often impractical and is a major
disadvantag of membrane liners. Where greater thermal resistance than
the wood itself is required, near-hydrophobic insulation may be placed
on the inside wall of the tank and covered with a liner (Figure 5-1).
Steel tanks can be either bolted or welded. Small tanks of
less than 200 m3 could be barged complete but larger ones must be
constructed on-site. Bolted tanks ar quickly erected; however, any
damage to the plates during shipping will make alignment difficult and
leaks may occur. Leakage at the joints may occuur due to misalignment,
poor erection or foundation movement. The insulation and coating must
consider such movements and leakage. Welding is the preferred method of
construction, particularly for large tanks (i.e., greater than 2000 m3).
However, qualified welders and vacuum and radiographic equipment to check
the welds are necessary.
Special low-temperature, high-impact steels, such as ASTM A-516
or CSA G40.8, are advisable where the tank may remain empty during the
winter and reach the lowest ambient temperature. The designer must
assess the risk of this situation. Because of the high cost of special
steels, conventional steel has been generally used for insulated water
storage tanks. Welded steel tanks have been insulated with polystyrene
or polyurethane boards and with sprayed-on polyurethane. Figure 5-2
illustrates a welded steel tank with board insulation and metal
cladding.
Steel tanks must have an anti-corrosion lining such as an epoxy
paint system. The minimum temperature conditions required during the
installation and curing are significant to construction scheduling.
Failure to achieve this and follow manufacturer's instructions are major
causes of premature lining failures. The cost of sandblasting and liner
installation is very high in remote locations; therefore, the liner system
should be selected for the best ovaerall economics, not just the initial
cost. Alternatives such as membrane liners or electrical corrosion pro-
tection systems such as anodes or impressed current may be considered.
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5-4
Access hatch
Tank diameter = 9 6 m
Ladder
100 0 Overflow
65 0 Recirculatmg return line
Pipe and ladder support
Tank base
300 x 300 mm Tank beams
Wood pile at 1 4 m spacing
Wrap in 30 mil PVC liner material
Bolt
Tank shell
Polystyrene
LINER SUPPORT DETAIL
Liner
Tank shell
Two-25 mm layers of polystyrene board insulation
Metal jacket
50 mm Polyurethane insulation
300 0 Supply line and carrier pipe
Pipe support
Drift pin
Ground level
FIGURE 5-1. WOOD TANK WITH INSULATION AND LINER ON INSIDE
(on pile foundation)
Access hatch
Metal cladding
M.
Metal flashing
Tank roof
50 mm Polystyrene board insulation
- Insulation anchors at 600 mm spacing
• Welded steel tank wall
25 mm Polystyrene board insulation
-40 mm Polystyrene board insulation
• 20 x 0 5 mm Stainless steel bands 450 mm spacing
900 x 0 625 mm Metal (aluminum) cladding sheets
approximately 12 m long
200 mm Gravel
-Tank floor
-Polystyrene board insulation
FIGURE 5-2. STEEL TANK WITH BOARD INSULATION AND METAL CLADDING
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5-5
Concrete tanks have been used where adequate aggregate is
available and the foundation is rock or where soils permit slab
construction. They should be covered with earth where practical to
reduce heat loss and insulated if necessary (Figure 5-3).
5.2.2 Insulation
Insulation may be earth cover, wood, fibreglass batt,
polyurethane or extruded polystyrene boards. The typical 75-mm walls of
wood tanks provide some insulation value, but the thermal resistance of
concrete and steel is negligible. The thermal inertia of soil dampens
out the extreme air and ground surface termperatures, while fibreglass,
polyurethane and polystyrene provide thermal resistance to reduce heat
loss. Only moisture resistant insulation should be installed in contact
with storage tanks which are inaccessible or below ground, since moisture
from leaks, condensation, rain or groundwater can drastically reduce the
insulating value.
Tanks of any material can be enclosed within a building shell.
Such an exterior frame and shell may be constructed against the tank or a
walkway may be provided between the tank and the exterior wall (Figure
5-4). The wind protection and air gap will reduce heat losses and
this can be further reduced by insulating the enclosure. Where access to
the insulation is provided, such as by a walkway, fibreglass batt
insulation can be used (Figure 5-4).
Near-hydrophobic plastic foam insulations are readily available
and commonly used. Polyurethane may be foamed on-site, reducing the
shipping costs; however, field costs may be higher. Polyurethane boards
may be made up, but the foam is more commonly sprayed directly onto the
storage tank surface (Figure 5-5). To ensure a good bond to a metal
surface loose scale and paint flakes should be removed, the surface should
be solvent-cleaned if it is oily and a compatible primer applied. Foamed-
in-place insulations are particularly useful for insulating curved sur-
faces or places that are difficult to reach. Spraying must not be carried
out in the presence of water, rain, fog, condensation, wind velocities
greater than 5 km/h, when the tank surface temperature is below 10°C, or
when the air temperature is below 2°C without special techniques and heating
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5-6
Backfill mound
Original ground level
Sloped
Rolled roofing and granular sufaced
50 x 300 mm Tongue and groove wood decking
^^- mm Polystyrene board insulation
Galvinized steel joists
1 00 mm Polystyrene board insulation
250 mm Reinforced concrete walls and floor
0.1 mm Polyethylene film
FIGURE 5-3. INSULATED BURIED CONCRETE TANK
Ventllatlon L=— ^—Asphalt paper
100 mm Rockwool batt insulation •
Inner tank
Radius = 5 7 m
Outer tank
Radius = 8 2 m -
-Centre column
- Reinforced water-tight concrete
250mm 250mm-
I
300 mm
r
T
Metal cladding
Rock
FIGURE 5-4. ABOVE-GROUND CONCRETE TANK, GREENLAND
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5-7
FIGURE 5-5. STEEL TANK WITH 75-mm SPRAYED
ON POLYURETHANE INSULATION,
BARROW, ALASKA
equipment. Quality must be controlled during and after foaming. A high
degree of skill is required in application to ensure a smooth surface.
Polyurethane foam must be protected from vandalism, weather and from
ultraviolet light (sunlight). This can be done with low-temperature
elastomers or other coatings compatible with polyurethane which are
sprayed onto the insulation, usually in two or three coats, with the
first coat applied within one day of foam application. The walls can be
further protected by sheet metal cladding.
Extruded expanded polystyrene or polyurethane boards can be
glued and strapped (typically with 40 mm x 0.5 mm stainless steel
banding 450 mm on centre) to the outside of tank. Large tanks will
require clips. The boards should generally be less than 75 mm thick to
allow installation on the curved tank surfaces. Two layers are
preferable so that by staggering these, the joints can be covered. The
insulation must be protected from weather, and vandalism. This is
commonly done with metal cladding. Embossed, corrugated or ribbed
(i.e., not smooth) surfaces will not show bends or deformities incurred
during construction or operation.
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5-8
Near-hydrophobic insulation boards can also be used to insulate
the walls of below ground level concrete tanks. High density foams with
compressive strengths up to 700 kPa can be placed under a tank, if
desired (Figure 5-3). These higher density foams also absorb less
moisture.
Ice is a relatively poor insulator, l/60th that of polystyrene;
therefore, an ice growth on an insulated tank wall does not appreciably
reduce heat losses. However, ice is 20 times a better insulator than
steel and an ice layer will reduce heat loss better than an exposed
surface.
5.2.3 Design
Ice in water storage tanks can cause serious damage. A
floating ice sheet may destroy ladders, structural supports, pipes and
similar interior appurtenances as it rides up and down in the tank due
to fluctuations in water level. If these are attached to the tank wall,
failure can result. Ice formed on the tank walls can suddenly collapse,
e.g., when the walls warm up during warm weather, and cause failure or
puncture holes in the bottom of the tank. Therefore, water storage
tanks must be designed to prevent the growth of ice in the tank under
all foreseeable circumstances, including unusual operating conditions,
and they should be completely drainable. Because of their vulnerability
to ice damage, interior appurtenances should be installed with caution.
While it is usually easy to keep the stored water warm, parti-
cular attention must be paid to the air space above the free water
surface. The air in one Alaskan tank was 2.5°C below the water
temperature, but this will vary with the geometry, insulation and
outside temperatures [1],
Since water is most dense at 4°C, surface icing can be
prevented by operating the tank at a temperature greater than 4°C.
Continuous or intermittent circulation within the tank will also help to
prevent density stratification and surface or wall icing. The return
line of a recireulating water distribution system is often discharged
into the storage tank. This provides circulation and temperature
control within the tank, and a large heat reservoir for the system.
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5-9
Where practical, breather vents should be located on the
interior of the tank, venting into an attached pumphouse or building
rather than to the outside where ambient temperatures are low. This
will prevent the vent from icing up due to condensation and will reduce
heat loss. The vacuum created by a blocked vent when the water level is
lowered can cause the tank to collapse.
Overflow piping should be designed so that a trickle flow does
not iee up and eventually block the pipe. It should be insulated and
heat traced if located outside the tank or perhaps run inside the tank
(Figure 5-1).
Instrumentation should include a non-contact water level
elevation (head) indicator, sueh as a pressure transducer, since ice
would damage floats. Temperature monitoring at various levels for
control and alarms should be installed.
Seasonal storage, e.g., where complete winter storage is
required, can cause water quality changes, such as reduced oxygen.
Chlorine residuals will also decrease with time, though less with colder
waters [2], Because of the effects of long-term storage on water
quality, treatment should occur after storage.
Elevated tanks can provide the necessary pressures in the
distribution system; however, they can be a maintenance problem in cold
weather. The large surface area and high winds increase heat loss, and
the standpipes must be freeze-protected. The foundation must be
carefully designed. In small communities a pneumatic system or constant
pressure pumps fed from a surface storage tank are generally more
practical.
Freezing of a storage tank will not usually occur all at once.
Layers of ice are formed over several hours or days. Periodic drawdowns
cause such layers or plugs to become hung up and separated by air gaps.
If this occurs, precautions must be taken to prevent the piston action
of a falling ice layer. Thawing of an ice layer should be carried out
from the top. The method and sequence of thawing a particular tank must
be designed into it and specified in operational procedure manuals.
Extra equipment required must be supplied at the time of construction.
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5-10
5.2.4 Thermal considerations
The thermal characteristics of alternative designs should be
considered, although in many oases the size, shape and location are
specified by other constraints. Elevated tanks expose the greatest
surface area and must contend with low air temperatures and high winds.
Tanks at the ground surface will lose less heat and the common vertical
cylinder shape is very near optimum, since heat loss to the ground is
less than to the air. Whenever practical, tanks should be buried or
covered with soil to reduce the effect of low air temperatures.
All exposed surfaces should be insulated. This is particularly
important for steel tanks since the heat loss through exposed steel,
where the only resistance is air film, will be at least 50 times that of
a tank surface insulated with 50 mm of polystyrene. Thermal breaks or
penetrations such as a ladder attached to the tank exterior must be
avoided or reduced. The risers for elevated tanks must also be
insulated.
Exposure of inflow, outflow and circulation piping should be
minimized, perhaps by using a common carrier (e.g., pipe in a pipe). A
common carrier also reduces the number of connections into the tank,
which is of importance for lined tanks.
The exterior surface could be painted a dark colour to absorb
as much incident radiant heat as possible during the long dark winters.
The economic thickness of insulation can be determined by
comparing the initial capital cost for increased insulation thickness
to the accompanying reduced heat loss, and lower annual energy cost and
heating capacity requirements (see Section 15). Other considerations
such as a required maximum rate of heat loss or temperature drop over a
specified period may require greater than this minimum thickness.
Thermal calculations are also necessary to size heating systems to heat
water and to replace heat losses. For storage tanks, piping and other
utility system components, the required capacity is based on supplying
the maximum rate of heat loss, whereas the total energy consumption is
based on the annual heat loss. The heating of water in storage tanks by
the practical application of alternative energy sources, such as wind
-------
5-11
and low temperature waste heat from electrical generation, should be
considered (see Section 14).
Heat loss can be reduced only slightly by operating the tank
near freezing since it is the temperature difference that determines
heat loss. For example, if the ambient temperature is -20°C then there
will be a 12% reduction in heat loss for a tank operated at 2°C compared
to at 5°C. The lower the ambient temperature, the less are the savings
by reducing the tank temperature. There are, however, energy benefits
to operating near freezing where the mean air temperatures are not much
below freezing, and where this eliminates or reduces the need to preheat
raw water supplies.
Operation at over 4°C will prevent density stratification
and surface freezing, but operating at over 10°C is usually unneces-
sary and can result in vent icing problems. The large mass of water
reduces the potential for freezing and damage from failures, such as
prolonged stopages of heat input. In any case, the tank should be
completely drainable.
Small storage tanks may be located within a building. Some
innovative examples of this are the Kemi, Finland, multi-story city hall
which incorporates an elevated storage tank, and the British Petroleum
camp near Prudhoe Bay and several new schools in Alaska where the
swimming pool doubles as water storage for fire protection.
5.2.5 Foundation
Foundation considerations are similar to those for other
northern buildings, with the added concern of the high weight of
water-filled storage tanks. In non-permafrost areas, normal foundation
precautions should be considered, including those for frost heaving. In
permafrost areas, active or passive design measures can be used. Active
measures include pre-thawing, excavation and replacement, and designing
for settlement. Passive measures include those that separate the tank
from the ground and those that maintain the permafrost. An example of
the former is the use of piles. The heavy loads require close spacing
of piles and a design analysis which considers the creep of frozen
ground, particularly in "warm" permafrost areas. Examples of the latter
-------
5-12
are artificial refrigeration, thermal piles, and air ducts (with or
without fans).
5.2.6 Costs
Table 5-1 shows typical costs for water storage tanks in cold
regions.
5.3 Earth Reservoirs
5.3.1 General
Water impoundments for domestic [3] and industrial water supply
[4] and dams for hydro power generation [5] have been successfully
constructed in the North. Special design considerations are required in
permafrost areas, particularly in high ice content soils [6],
Construction problems may include lack of specific soils required for
embankment construction, excavation and placement of frozen soils, and
other northern construction problems such as logistics and weather (see
Section 2).
The effective reservoir volume can be reduced substantially by
ice cover which can at times be 2 m thick. The most critical years will
be those with low snowfall. Ice thickness can be reduced to a limited
extent by using snow fences to create snow drifts, thereby insulating
the surface. Deep reservoirs can be used to minimize surface area and
thus reduce the volume of frozen water.
5.3.2 Water quality
The quality of the water is influenced by the soils and vegeta-
tion that it comes into contact with. Leaching from bog soils and
oxygen depletion during long periods of ice cover will necessitate water
treatment for colour, pH, taste and odour prior to use. These effects
should be considered in preparing the bottom of the reservoir before
flooding [7]. Water quality is also affected by ice growth. Thermal
stratification may influence the location of intakes. It is normally
desirable to dyke the edges to prevent unwanted runoff from entering the
reservoir. Signs, in appropriate languages, and fences are necessary to
deter access to reservoirs by animals and unauthorized personnel.
-------
TABLE 5-1. WATER STORAGE TANK COSTS
LOCATION
Ft. McPherson, NWT
Resolute Bay, NWT
Inuvik, NWT
Savoonga, Ak.
Shismaref, Ak.
Unalakleet, Ak.
Twin Hill, Ak.
Stebbins, Ak.
Grayling, Ak.
SIZE
3
450 m
3
450 m
3
2250 m
3
380 m
3
1140 m
3
3780 m
3
230 m
3
1900 m
3
230 m
Tank
Wood
Bolted Steel
Welded Steel
Welded Steel
Welded Steel
Welded Steel
Welded Steel
Welded Steel
Welded Steel
DESCRIPTION
Foundation
Piles
Insulated Pad
Piles
Pad
Pad
Pad
Pad
Pad
Pad
5
5
6.2
7.5
7.5
7.5
7.5
7.5
7.5
Insulation
cm polystyrene
cm polystyrene
cm polystyrene
cm polyurethane
cm polyurethane
cm polyurethane
cm polyurethane
cm polyurethane
cm polyurethane
COST (YEAR)
$166 000 (1975)
$190 000 (1976)
$750 000 (1976)
(estimated)
$106 000" (1977
$176 000- (1977
$308 000- (1977
$ 78 000* (1977
$212 000* (1977
$ 80 000* (1977
Does not include foundation. Foundation costs in Alaska were $65 000 for a gravel pad or $170 000 for
piling with a floor system.
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5-14
5.3.3 Dams
Dams may be constructed to raise the Level of an existing lake
or create a reservoir on a stream or river. Overtopping is not
permissible; therefore, overflow structures must be provided. Runoff at
spring breakup from northern watersheds tends to be very short and
violent, thereby increasing the size and complexity of the spillway.
Floating ice and wave action must be considered in large reservoirs. The
force of ice bonded to dam structures can be significant when it is
raised or lowered with the fluctuating water level.
5.3.4 Diked impoundments
Dugout type, generally cut and fill, earth reservoirs may be
periodically filled by pumping or by siphoning water from a nearby
source. This eliminates expensive overflow structures and simplifies
inflow and intake requirements. The low head reduces seepage and
embankment stability design problems; however, the effective reservoir
volume is reduced by ice growth. Groundwater seepage into a reservoir
can be a problem, and must be considered in the geotechnical investiga-
tion, even in permafrost areas, since sub-permafrost or intra-permafrost
groundwater may be encountered. Impervious membranes have been used
successfully in the central and eastern Arctic where the native soils
are generally permeable sands and gravels with some silt [3],
To reduce or eliminate excavation of frozen soils, a reservoir
may be constructed by impounding embankments. The higher head will
increase the importance of seepage control and embankment stability.
The design of a dugout and diked impoundment for a wastewater
lagoon is similar to a water supply reservoir.
5.3.5 Impervious liners
Many techniques and types of natural and synthetic linings have
been used to reduce or prevent seepage from water reservoirs and
wastewater ponds [8], In cold regions where impervious soils are not
readily available, the thin film synthetic liners have been popular,
although spray-on liners, including polyurethane, have been used to seal
petroleum product storage tank areas [9],
-------
5-15
Impervious liners may be used within the embankment only, or to
seal the entire reservoir (Figure 5-6). Folds may be left in the liner
to allow for settlement; however, large differential settlements such as
in high ice-content soils should be avoided or designed with caution.
Groundwater or the thawing of permafrost under the reservoir may create
hydrostatic uplift pressures or icing conditions. These can be relieved
by underdrains, well points or pressure relief valves. The liner must
be adequately protected from ice action to prevent punctures during
installation and operation (Figure 5-7).
The liner material must be approved for the application, for
example, potable water, must be suitable for low temperatures and
freeze-thaw conditions, and durable enough for shipping and installation
[3,10], The ease of field seaming and repairing punctures is also
important in selecting a liner system. There are numerous liner
materials available but few are suitable for the rigorous installation
and operating conditions associated with cold regions. Thin plastic
films (4, 8 and 10 mil polyethylene and PVC) have failed at heat-sealed
joints. Exposed portions were punctured by the gravel base and ripped
by falling ice as the water level lowered. If adequately bedded and
covered, weak films as thin as 10 mil can perform satisfactorily but
even the most suitable material must be installed properly and with
care. Membranes of high puncture strength and elasticity will require
less intensive bedding preparation and installation restrictions than
more fragile ones. Successfully used liner materials include hypalon
synthetic rubber, chlorinated polyethylene (CPE), and Dupont 3110
elasticized polyolefin.
Manufacturers and suppliers must be made aware of the
anticipated installation and operating conditions. New materials or
requirements should be laboratory tested under extreme conditions such
as those outlined by Foster et al [3],
5.3.6 Foundations and thermal considerations in permafrost areas
Impounded bodies of water disturb the natural ground thermal
regime. In permafrost areas, a permanent thaw bulb is created beneath
water bodies that do not freeze to the bottom. In ice-rich soils this
thawing may cause structural and seepage problems for the reservoir and
-------
-------
5-17
the containing embankments or dam. The structural problems are essen-
tially two-fold. Firstly, the thaw-consolidation of underlying ice-rich
soils creates differential settlement, and secondly, excess pore-water
pressure generated in fine-grained soils as the thaw front advances can
cause failure.
Foundations and thermal consideration provide the main design
problems. The main construction problems are availability of soils and
excavation and placement of frozen soils.
The thermal regime and, in particular, the thaw boundaries can
be estimated by two and three-dimensional analysis and the settlement
calculated from the soil and temperature conditions [6], The most
sensitive area with regard to stability is under or adjacent to the toe
of the upstream slope. Some differential movement may be tolerated in
low head dams as long as the overall stability and seepage control are
adequate.
Seepage reduction or elimination is important in the thermal
design as well as the functional design. In the former case, sensible
heat transport by seepage will result in embankment temperatures only
slightly lower than that of the reservoir water [5], This will promote
deep thawing under the embankment with its associated problems. Icing
will occur at the toe of seeping embankments.
Passive foundation designs are based on preventing the embank-
ment from thawing. Thawing under the reservoir is inevitable and would
be impractical to arrest. In very cold regions with a shallow active
layer, the permafrost may rise in the embankment resulting in a natural
impervious frozen core [11]. In warmer regions, hydrophobic insulation
and/or cooling may be necessary to maintain a frozen core and
foundation. Vertical air ducts with natural draft or blowers to induce
winter air circulation and refrigeration have been used in dam
construction. These measures have high capital and operating costs, but
may be necessary for high embankments on thawing ice-rich soils.
Active designs allow thawing but any resulting settlement or
instability is considered. Such "thawed" designs are necessary in the
discontinuous permafrost zone. Measures to decrease the total thaw or
rate of thawing may be required. Settlement can be reduced by natural
-------
5-18
or artificial pre-thawing or excavation of the high ice content
near-surface organic and soil layers. These expensive measures may be
limited to the embankment foundation and selected areas. Where
differential settlement is expected, self-healing semi-impervious
embankment material, such as sand, should be used, although this allows
seepage which will promote thawing. Maintenance approaching rebuilding
may be required in the first few years [12],
5.4 References
1. Cohen, J.B. and Benson, B.E. "Arctic Water Storage", Journal
American Water Works Association, j>0_(3) :291-297, 1968.
2. Nehlsen, W.R. and Traffalis, J.J. "Persistanoe of Chlorine Residuals
in Stored Ice and Water", U.S. Naval Civil Engineering Research
and Engineering Laboratory, Port Hueneme, California, Technical
Note N-206, 1954.
3. Foster, R.R., Parent, T.J. and Sorokowski, R.A. "The Eskimo Point
Water Supply Program", In: Utilities Delivery in Arctic Regions,
Environment Canada, Environmental Protection Service, Report No.
EPS 3-WP-77-1, Ottawa, Ontario, 1977.
4. Rice E.F. and Simoni O.W. "The Hess Creek Dam", In: Proceedings,
Permafrost International Conference, Lafayette, Indiana, 1963,
National Academy of Science, Washington, D.C. pp. 436-439, 1966.
5. Brown, W.G. and Johnston, G.H. "Dykes in Permafrost: Predicting
Thaw and Settlement", Canadian Geotechnical Journal, _7(4): 365-371,
1970.
6. National Research Council of Canada, "Permafrost Engineering
Manual - 1 Design and Construction", National Research Council of
Canada, Ottawa, in preparation.
7. Smith, D.W. and Justice, S.R. "Effects of Reservoir Clearing on Water
Quality in the Arctic and Subarctic", Institute of Water
Resources, University of Alaska, Fairbanks, Alaska, IWR-58, 1975.
8. Middlebrooks, E., Perman, C.D. and Dunn, I.S. "Wastewater
Stabilization Pond Liners", U.S. Army, Cold Regions Research and
Engineering Laboratory, Hanover, New Hampshire, In preparation.
9. EBA Engineering Consultants Ltd. "A Study of Spray-on Liners for
Petroleum Product Storage Areas in the North", Environmental
Impact Control Directorate, Environmental Protection Service,
Environment Canada, Report No. EPS 4-EC-77-2, Ottawa, Ontario
1977.
-------
5-19
10. Thornton, D.E. and Blackall, P. "Field Evaluation of Plastic Film
Liners for Petroleum Storage Areas in the Mackenzie Delta".
Environmental Conservation Directorate, Environmental Protection
Service, Environment Canada, Report No. EPS 3-EC-76-13, Ottawa,
1976.
11. Fulwider, C.W. "Thermal Regime of an Arctic Earthfill Dam", In:
North American Contribution PERMAFROST Second International
Conference, 13-28 July, 1973, Yakutsk, U.S.S.R., National Academy
of Science, Washington, D.C. p. 662-628, 1973.
12. Cameron, J.J. "Waste Impounding Embankments in Permafrost REgions:
The Sewage Lagon Embankment, Inuvik, N.W.T.", In: Some Problems
of Solid and Liquid Waste Disposal in the Northern Environment,
Slupsky J.W. (ed), Environmental Protection Service, Environment
Canada, Edmonton, Alberta, EPS-4-NW-76-2, pp. 141-230, 1976.
5.5 Bibliography
Alter, A.J. and Cohen, J.B. "Cold Region Water Storage Practice",
Public Works Magazine, October, 1969.
Branch, J.R. "Evaluated Water Tank Freeze-up: A Freeze-up
Experience", Journal American Water Works Association, 60(3);291-297,
1967.
Shoblon, G. and Oliver, R.H. "An Evaluation of Foamed Polyurethane
for Containment Dike Liners". A report prepared for the Technical
Committee on Petroleum Dyking in the North, G. Shoblom and R.H.
Oliver, Cominco Ltd., Trail, British Columbia, 1976.
Eaton, E.R. "Floating Plastic Reservoir Covers in the Arctic", Solar
Energy. _8(4):116, 1964.
Foster, R.R. "Arctic Water Supply", Water and Pollution Control,
_3(3):24-28, 33, March, 1975.
Larson, L.A. "Cold-weather Operation of Elevated Tanks", Journal of
American Water Works Association, 68(1):17-18, 1976.
Toman, G.J. "Elevated Water Storage Tank Freeze-ups: Correction of
Freeze-ups", Journal American Water Works Association, 59(2);166-168,
February, 1967.
Wormald, L.W. "Water Storage Tank Failure Due to Freezing and
Pressurization", American Water Works Association Journal,
64(3):173-175, March, 1972.
-------
SECTION 6
WATER DISTRIBUTION
Index
Page
6 WATER DISTRIBUTION 6-1
6.1 Introduction 6-1
6.2 General Assumptions and Design Considerations 6-1
6.3 Self-Haul Systems 6-3
6.3.1 Watering point design 6-3
6.3.2 Types of systems 6-4
6.4 Community-Wide Haul Systems 6-5
6.4.1 Water loading point design 6-6
6.4.2 Vehicle sizing and design 6-11
6.4.3 Ice haul 6-16
6.5 Piped Systems 6-17
6.5.1 Above or below-ground 6-18
6.5.2 Types of systems 6-18
6.5.3 Other methods 6-26
6.6 Service Lines 6-28
6.6.1 Method of circulation 6-28
6.6.2 Materials 6-30
6.6.3 Dual servicing 6-30
6.7 Materials of Construction 6-33
6.7.1 Category 1 materials 6-34
6.7.2 Category 2 materials 6-35
6.7.3 Other types of pipe used 6-37
6.7.4 Miscellaneous fittings 6-37
6.7.5 Insulation 6-38
6.8 Appurtenances 6-38
6.8.1 Hydrants 6-38
6.8.2 Valves 6-40
6.8.3 Metering 6-40
6.8.4 Manholes 6-42
6.8.5 Alarms and safeguards 6-45
-------
Index (Cont'd)
Page
6.9 Backup Freeze Protection Mechanisms 6-45
6.9.1 Heat trace systems 6-45
6.9.2 Thaw wire electric resistance systems 6-46
6.9.3 Steam or hot water thawing 6-46
6.9.4 Freeze damage prevention 6-47
6.10 References 6-47
6.11 Bibliography 6-48
-------
List of Figures
Figure Page
6-1 Self-Haul Watering Point (Greenland) 6-3
6-2 Overhead Truck Fill Point 6-7
6-3 Water Truck Fill Point (Greenland) 6-7
6-4 Water Truck Fill Point with Hose Nozzle Fill 6-8
6-5 Bottom Fill Point 6-9
6-6 Truck with Flotation Tires for Traction in Snow 6-13
6-7 2225-Litre Water Trailer 6-13
6-8 Water Delivery Truck Tank Body Piping and Equipment
Diagram 6-15
6-9 Tracked Vehicle Used for Ice haul 6-17
6-10 Layout and Location of Mains for Single-Pipe
Recirculation 6-20
6-11 Single-Pipe System without Recirculation 6-22
6-12 Typical Utilidor and Packaged Preinsulated Pipe 6-23
6-13 Dual Pipe System 6-24
6-14 Dual Main Sub-System 6-25
6-15 Small Diameter Water Mains 6-27
6-16 Flushing Hydrant System 6-29
6-17 Water Service Line 6-31
6-18 Above-ground Service Line 6-31
6-19 Above-ground Service Line Take-offs 6-32
6-20 Underground Valve and Box 6-32
6-21 Dual Servicing 6-33
6-22 Supported Pipe Take-offs 6-35
6-23 Above-ground Hydrant i 6-39
6-24 Below-ground Hydrant 6-41
6-25 Mini Service-centre Manhole 6-43
-------
6-1
6 WATER DISTRIBUTION
6.1 Introduction
Throughout this section the various methods of distributing
water from source to user will be discussed in the following categories:
General: a general discussion on why or when the particular system
is applicable and suitable to a given northern situation.
Objectives: the objectives that should be achieved when designing the
particular system for northern conditions.
Existing Systems: descriptions of systems that have or have not worked.
Water distribution is carried out in three main ways. These
are self-haul, community-wide haul (trucked water or ice) and piped
systems. The system which should be used in any given situation depends
on a number of factors:
- governmental policy,
- population,
- geographic and physical site location conditions,
- economic base of community,
- health standards,
- available technical skills,
- ability and willingness of community to operate and maintain
the facilities.
Given the factors involved for a particular northern community,
a detailed economic analysis must be carried out to determine which is
the most appropriate system for that community.
In the Northwest Territories, general terms of refrence [1]
have been prepared for use in carrying out the economic analysis.
6.2 General Assumptions and Design Considerations
Average residential consumption of water in areas serviced by a
trucked water delivery and sewage collection systems is generally 95 I/
person/day for a four person household with conventional plumbing.
Water conservation fixtures (e.g., low water use toilets) can reduce
consumption and should be a necessary part of future building design for
most northern communities.
-------
6-2
Present consumption in houses without plumbing is less than
20 L/person/day. However, concurrent with the gradual improvement of
housing in the North will be a gradual increase in per person consumption
of water. Residential areas serviced by a piped water delivery system and
trucked sewage collection system will have an average water demand of 140
L/person/day immediately. Communities totally serviced by a piped water
distribution and sewage collection system will have an average water demand
of 450 L/person/day, including industrial uses. The average residential
water demand will be 270 L/person/day.
For communities with a poor road system it is not practical to
design water and sewage trucks to carry greater than 4550 litres per load.
Building water and sewage tanks should be sized for a minimum of
five and seven days capacity, respectively.
Community population projections are available from the
appropriate government departments: in the Northwest Territories and the
Yukon, the Department of Local Government; and in Alaska, the Department
of Community and Regional Affairs. These projections should be utilized
in planning community systems.
Fire protection requirements for system designs incorporating
full fire protection capability or otherwise are noted in Section 12.
6.3 Self-Haul Systems
The self-haul system has limited application and a number of
drawbacks which often make it undesirable for water distribution.
In northern Canada this mode is practiced mainly in small unin-
corporated settlements of 50 people or less where no mechanization yet
exists, e.g., the people obtain their water from a nearby lake or river
and haul it to their house.
As the community grows, the increased population density often
results in sewage contamination of the drinking water source and the need
to provide central water points where people can pick up safe chlorinated
water. These watering points are usually only installed when the community
doesn't have the necessary infrastructure, i.e., roads, holding tanks for
water in houses with exterior fill points, sewage pump-out tanks, etc.,
to accept a trucked water and sewage system.
-------
6-3
The trucked water system is preferred where possible over a
central pick-up watering point. The reasons for this are:
- more positive means of supplying housing units on regular
basis with clean safe water,
- allows increased water usage and thus better hygiene,
- housing units with pressure systems can eventually be hooked
onto piped systems with minimum problems,
- unsupervised watering points tend to be vandalized and become
both unsanitary and quickly nonoperational.
6.3.1 Watering point design
Watering points (see Figure 6-1) are usually operated in
conjunction with some other form of water distribution or supply
system. They are often located in older parts of a community where the
houses are not equipped for a trucked or piped system. In Alaska they
are constructed as an interim solution to provide safe drinking water
until distribution of some sort is feasible.
FIGURE 6-1. SELF-HAUL WATERING POINT (Greenland)
-------
6-4
The failure rate of the self-haul watering point is very great.
Almost six out of 10 are nonoperational after one year. This is mainly
due to vandalism, freeze-ups, poor design, and lack of supervision and
management. Because of these problems the water points are usually
abandoned and not repaired.
Objectives of the ideal self-haul watering point are:
- maximum cleanliness and sanitation in getting water to the
container,
- minimum maintenance,
- material design to minimize vandalism.
6.3.2 Types of systems
6.3.3.1 Exterior unsupervised. This is a small heated building con-
taining a water tank, water piping and valves. The user either pulls a
chain from outside the building or pushes an electrical button activating
a solenoid valve which releases water through a spout into his container.
When he releases the button the valve closes and the remaining water in
the line drains out the spout. A similar mechanical spring-loaded lever
can also be used. A suitable splash base of gravel and rocks or slotted
boards is required below the spout. A hanger for the water container is
also normally provided. The exterior of the building must be made as
vandal-proof as possible. Native logs or heavy duty siding is preferable
to normal "metal type" siding. Concrete block would also be ideal if
feasible for the location. The entrance door is kept locked and only the
maintenance man should have access.
The tank could be filled by truck from the outside, and again
access to the inside would be prohibited. A light outside would indicate
that the tank is full. Failure to stop filling when the light oomes on
would result in the tank overflowing outside through a vent pipe.
Usually two lights are used in case one burns out, which is also an
indication for the maintenance man to replace it. Similar on-line
systems in conjunction with water distribution mains are also used.
6.3.3.2 Interior watering points must be supervised. Otherwise, the
door to building will be left open, and the system will either freeze up
or be vandalized.
-------
6-5
6.3.3.3 Central facilities are discussed in detail in Section 11.
6.3.4.4 Containers. The type of container recommeded is a 20 L
enclosed plastic "camper" type water container to minimize contamination.
What is used in practise is anything that will hold water, usually an
open water pail.
6.4 Community-Wide Haul Systems
Community-wide haul systems are those systems which transport
water from a water or ice source or watering point to a fill point at the
individual houses. This is usually accomplished using a tracked, towed
or wheeled vehicle.
The "truck" or vehicle-delivery system is used in all or
portions of most communities in northern Canada where the population
ranges from 50 to 1500. Generally, it becomes more economic to pipe
water when the population reaches a range between 600 and 1,000 people,
depending on the location and conditions. At this point a dual system of
both trucked and piped water continues until the existing areas are put
on piped service. In Alaska the truck-haul system has been found
expensive to operate and maintain. Piped delivery systems and/or central
pick-up is preferred in most cases. However; circumstances in each
community must be considered on an individual basis. No subsidy is
offered for operation of water delivery systems in Alaska.
In a nonpiped community, the water loading point for the veh-
icles is usually a prefabricated building on the shore of a lake or river,
or beside a well. Vehicle system costs can be reduced at some communities
by construction of a water supply pipeline from a distant water source.
6.4.1 Water loading point design
Objectives for the design of the water loading point are:
- maximum cleanliness and sanitation,
- minimum spillage and subsequent freezing and ice buildup
around the water point,
- efficient truck entry and exit routes taking into considera-
tion prevailing winds and snow drifting,
- minimum maintenance requirements.
-------
6-6
There are four types of systems used:
- overhead pipe loading,
- hose nozzle fill,
- bottom loading,
- interior building fill point.
6.4.1.1 Overhead pipe filling system. Figures 6-2 and 6-3 show
typical overhead systems. Included in such a system would be an exterior
key start switch for the water pump. Often the water delivery is done by
a private contractor, and only the contractor is given the key. All
water pumped out is registered on a meter inside the building. Access to
the inside of the building is limited to maintenance personnel.
The loading arm drains in two directions after each filling.
From the high point it drains back to the heated building and from the
spout into the truck. Thus freezing is prevented when the fill point is
not in use.
A swivel type elbow allows the loading arm to swing away if hit
by a vehicle. This often happens in the winter when the snow and ice
builds up so that the top of the truck is close to touching the fill pipe
A major problem with this type of fill design is that,
invariably, the key gets turned off when the truck tank is overflowing.
This leads to ice buildup on the ground which makes it hard for the truck
to park and often is the cause of the building siding being damaged by
the vehicle. Guard rails should be used to protect the building, and the
water fill pipe should be located such that the downspout is far enough
away from the building and high enough off the ground to compensate for
seasonal snow and ice buildup. To prevent splashing during filling and
to compensate for the seasonal variation in height, flexible low
temperature rubber hose should be connected to the bottom of the
downspout, as shown in Figure 6-3.
6.4.1.2 Hose nozzle filling system (Figure 6-4). In an effort to
prevent spillage and ice buildup, a fill point using a gas tank fill
hose nozzle has been used. The truck drives by a wooden platform, a
small door in the loading point building is opened, and a hose nozzle is
-------
• 75 Swivel elbow
6-7
kamlock' quick coupler -
Low temperature
rubber hose
w^/^Mm^/j^/^0^mfl
FIGURE 6-2. OVERHEAD TRUCK FILL POINT
FIGURE 6-3. WATER TRUCK FILL POINT (Greenland)
-------
6-8
Water distribution pumphouse
00 \.\\\ //// 00
FIGURE 6-4. WATER TRUCK FILL POINT WITH HOSE NOZZLE FILL
pulled out through roller guides. A platform is provided such that the
driver can take out the hose nozzle, put it in the top of the truck, and
then turn on the key start. The nozzle is designed to turn off under
back pressure. However, more often than not it is thrown in the open top
hatch of the truck locked in the open position. When the driver sees the
tank is full he turns the key off and puts the hose back in the cabinet.
The hose is such that it is long enough to reach the truck but not long
enough that it could touch the ground.
While this design does not totally eliminate water spillage
because of misuse, it has greatly reduced the amount of spillage compared
to the overhead fill pipe. There is some spillage when the driver pulls
the hose out of the tank and puts it back in the building.
6.4.1.3 Bottom filling system (Figure 6-5). The third type of system
utilizes an aircraft refueling technique. A bottom liquid loading device
as shown in Figure 6-5 is provided and the truck is filled through the
water source suction inlet at the back of the tank.
-------
Water meter
Flow control valve
75 0 Bottom liquid loading devi<
mounted on tee flange with 75 6
Kamvalok dry disconnect coupli
Water
supply
3000
Elevation B-B
300
;>v/.^:^~Yv~i'.:V; vVrrf 15 M at 250 E.W.
_ 900 mm sq.
concrete block
Three way valve •
120 L Solution tank with
chlorinator
Unit heater
Flow control valve
Storage for calcium hypochlorite drums
Unit
heater
B
100 mm Thick insulate
floor, wall, and roof
panels and doors
Truck
loading zone
\ \
\ \
\>
Water meter
FIGURE 6-5. BOTTOM FILL POINT
-------
6-10
Again, the filling point is separately housed with access for
maintenance.
To prevent overfilling the truck a batch meter is provided that
can be set by the truck driver for the tank capacity of the truck. The
bottom loader is swung out, connected to the back of the truck via a
quick connect coupling, the volume desired punched in on the batch meter,
and the pump turned on using key start. The meter shuts off the pump
when the preset amount is reached, the loader arm is disconnected and
swung back into the compartment, and the door is shut. The quick connect
coupling between the loading arm and the truck is spring loaded so that
it closes on disconnection and only a small amount of water is
spilled.
6.4.1.4 Interior fill points. These consist of watering points
similar to the overhead type except that the fill point is inside the
water truck garage. This is usually only used when the community size is
small, 200 - 300 population, and the loading frequency is only once or
twice per day.
All new truck filling points in northern Canada are designed to
provide a minimum loading rate of 450 L per minute with a desireable rate
of 700 L per minute. The basis for the minimum filling rate is two-fold.
Firstly and most important fire trucks in an emergency must be refilled
as quickly as possible. The Fire Marshal has set a minimum rate of 450 L
per minute or 10 minutes to fill a 4500 L tank. The second reason is
economic, i.e., the quicker the fill rate, the less chance the operator
will sit in the cab and forget about the truck filling, and the shorter
the turn around time.
The truck filling points should be well-lighted because in many
areas there is total darkness in the winter and the truck's parking
position is critical no matter what the filling system.
The truck should be able to drive past the loading point where
at all possible. Backing up requires more time and often results in
minor accidents which damage a building or support structure. Snow
removal is also easier. The road should be built up higher than the
surrounding tundra and in line with the prevailing winds, to keep snow
from building up in front of the loading point.
-------
6-11
Where piped systems are available in a community the water truck
usually obtains water from the firehall or other suitable building that
has piped water service and appropriate connections for filling the
truck. Often the water truck and the fire truck are stored in the same
building and the filling point is inside the garage.
6.4.2 Vehicle sizing and design
Water and sewage pump-out trucks are designed so that the holding
tanks and filling or suction mechanism can be housed on a standard truck
chassis. This is also true of sewage pump-out vehicles.
The costs for wheeled and tracked water delivery vehicles in
1976 dollars are:
4450 L insulated tank unit $16 000
Cab and chassis, wheeled vehicle 10 OOP
Total Capital Cost $26 000
Tracked vehicle $26 000
2225 L tank unit 16 OOP
Total Capital Cost $42 000
Use of tracked vehicles is discouraged as much as possible
because of their:
- high initial cost,
- high annual maintenance costs and difficulty in obtaining
parts,
- short life expectancy,
- lower payload,
- slower speed and longer travel time from water
source to houses and back to water source.
Tracked vehicles are only recommended for those communities where there
are no roads or where it is impossible to get to the water source in
anything other than a tracked vehicle. An example of this would be a source
of water close to the community with road access only in the summer. In
this situation a pipeline from the source becomes very attractive because of
the high cost of operating the slow tracked vehicles.
-------
6-12
There are very few communities in northern Canada that still
use a tracked water vehicle. It has been found that in normal snow and
winter conditions a wheeled vehicle can adequately do the job. In areas
where very heavy snow and snow drifting conditions are experienced,
wheeled vehicles with four-wheel drive and large floatation tires are
being utilized with success (see Figure 6-6).
6.4.2.1 Truck and tank sizes. Larger tanks reduce the number of trips
to the water source. However, they are heavier and require larger
vehicles. Often, the condition of the roads in the community and to the
water source, access to buildings and other local conditions will dictate
the practical maximum size of tanks and vehicles. In very small
communities, truck tank units of 2225 L capacity are usually adequate.
However, 4550 L units are now being ordered even for these communities
since the cost difference between the two is small. Where roads and
community infrastructure are still rudimentary (no mechanics, etc.), 2225
L water trailer units are being purchased rather than wheeled or tracked
vehicles with the tank assembly mounted on the chassis. These units are
in all aspects the same as those mounted on truck chassis, except that
they are towed by a farm tractor or other suitable vehicle (see Figure
6-7).
The number of vehicles required depends primarily upon the total
community consumption, distance to the water source, the vehicle
characteristics and the efficiency of operation. Equations to estimate
the requirements and costs are presented in Appendix D. For typical
operations with little or no distance to the source and a water
consumption rate of 90 L/person/day, one 4550-L water truck can service a
population of approximately 250. If consumption was only 10 L/person/day,
it could service 1000 persons. If the source was 3.25 km away, the
number of persons served would be 160 and 850, respectively.
In the Northwest Territories, the truck tank capacities to date
have largely been sized and directly influenced by the low water
consumption due to a lack of plumbing. Public housing provided only
rudimentary domestic plumbing systems: a small water holding tank
(approximately 450 L), a sink and direct drain pipe to the outside, and a
honey bucket. With this arrangement water consumption is usually about
-------
6-13
>»*• £
FIGURE 6-6. TRUCK WITH FLOTATION TIRES FOR TRACTION IN SNOW
FIGURE 6-7. 2225-LITRE WATER TRAILER
-------
6-14
10 - 20 L/person/day. The public housing in the NWT now provides full
plumbing, pressurized systems with 1140 L water holding tanks, and 1140 L
sewage pump-out tanks. In these houses it is expected that water
consumption will reach 95 L/person/day, as is experienced in four-person
homes with full conventional plumbing on trucked systems in Yellowknife,
NWT. Water conservation measures can reduce this demand.
Since truck system costs are directly proportional to the
consumption, they will become more expensive to operate as the residential
and non-residential water demand increases with higher populations and/or
higher standards of housing and plumbing. At some point, it will become
more economical to install a piped supply line and/or distribution system
since these costs are less sensitive to the capacity requirements. A
complete evaluation of any given system can be made using the rationale and
equations given in Appendix F.
6.4.2.2 Vehicle design. Over the years water delivery vehicles and
sewage pump-out vehicles have continually been modified and improved to
meet the needs of northern conditions.
Truck tanks for northern use must be insulated and all working
systems protected from freezing (see Figure 6-8).
Vehicle specifications which reflect the state of trucked delivery
design at this time can be obtained form the Department of Public Works,
Government of the N.W.T., Yellowknife, N.W.T., Canada, and the U.S. Indian
Helath Service, OEH, Box 7-741, Anchorage, Alaska 99510.
The sewage pump-out vehicle uses a pressure vessel and vacuum
pump system to evacuate holding tanks. The inherent maintenance problems
associated with fluid passing through a pump are thus eliminated.
A prototype using this concept is being developed and tested by
private industry for water delivery. For water vehicles using the pressure
vacuum system the action is the reverse of a sewage vehicle, i.e., the tank
is pressurized to force the liquid out. Such a system has a high flow rate
and may have sufficient water flow and pressure to meet the unerwriter's
requirements for fire trucks as well as water delivery vehicles. Advantages
of this system include elimination of the problems of pump maintenance and
freezing. In addition, such a water delivery vehicle can be easily
converted to a sewage pump-out truck.
-------
A
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V V3 close V4
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FIGURE 6-8. WATER DELIVERY TRUCK TANK BODY PIPING AND EQUIPMENT DIAGRAM
-------
6-16
6.4.3 Ice haul
Ice as a water source and community ice haul as a means of water
distribution is carried out only where no other normal water source is
available. For example, in arctic Canada only one community, Grise
Fiord, still uses ice as a winter water source via icebergs locked in the
sea. In Alaska there are still a few communities, such as Barrow, that
use ice to supplement the normal water supply.
In numerous other communities ice is used as a winter water
source because of individual choice and preference. That is, some local
people in certain communities prefer the taste of water obtained from ice
to that of the delivered chlorinated water which is obtained from usually
small lakes. The taste of water from such lakes is affected by lack of
oxygen after prolonged ice and snow cover in the winter and presence of
organics. Ice obtained in this case is usually on an individual basis
and not supported or organized by the community.
The inherent high degree of labour and handling involved in
harvesting ice increases the possibility of contamination. Any system of
ice harvesting should minimize labour involvement as well as possible
sources of contamination in all phases of the operation, including
harvesting, storage and distribution.
When ice is harvested from icebergs, as is the case in Grise
Fiord, Canada, the distance from the shore to the bergs could be as much
as 8 km. Tracked vehicles are required to traverse the sea ice and
pressure ridges (see Figure 6-9).
Tracked vehicles with flat bed open boxes are used to harvest
and distribute ice in winter. In the summer the box is removed and a
water tank with a pumping attachment is fitted to the tracked vehicle.
The ice is cut with chain saws or axes. Electric chain saws
powered from the tracked vehicles are recommended to avoid contamination.
This operation is usually done by two men.
The ice is brought back and, if not distributed immediately, is
stored in an unheated parking garage to prevent contamination. The ice
delivered to each household is placed in the water holding tank to melt.
-------
6-17
FIGURE 6-9. TRACKED VEHICLE USED FOR ICE HAUL
(Grise Fiord, N.W.T)
Grise Fiord has a population of 94 and the annual operating
cost of harvesting ice is $36 000. Because of the high cost and severe
water restrictions in winter, plus the possible health hazard due to
contamination, such systems are replaced as soon as economic alternatives
are developed.
6.5 Piped Systems
As discussed earlier, piping systems are used because they are
the most efficient, safe and economical means of distributing potable
water given a population of usually greater than 1000 people. Alaska,
however, has piped systems in communities considerably smaller than 1000
population. The point at which piping systems become more economical
than trucked systems must be determined for each individual community
with its unique characteristics (see Reference [1]).
The systems outlined below describe the basic operation and
antifreeze mechanisms. Backup mechanisms will be discussed under a
separate heading.
Northern piping systems should be designed to:
- minimize energy input for operation,
- be simple to operate and maintain,
-------
6-18
- be protected against mechanical damage, vandalism and severe
climatic conditions,
- have a prime antifreeze mechanism with at least one backup
mechanism, if not two,
- be drainable,
- have a minimum 40-year design life,
- provide easy isolation of sections and service lines at any
time of the year,
- minimize on-site labour and,
- allow maximum use of the short construction season.
6.5.1 Above or below-ground
Whether the piping system is placed above or below-ground will
depend on the particular site conditions of a given location. Generally,
below-ground systems are preferred where at all possible. The criteria
for selection of above or below-ground systems are presented in Section 2.
Piping systems are described later in this section do not differ
in operation whether the system is above or below-ground. Only appur-
tenances of the system vary.
Above-ground systems have been used where ground conditions and
thaw do not permit the use of a buried system with any degree of success.
However, with the advent of more efficient insulating material, these
conditions are becoming less significant factors in choosing between
above and below-ground systems. Above-ground systems are becoming
economical only where ground conditions are very rocky.
In areas where there is no permafrost, pipes can be buried below
seasonal frost penetration. However, this may be impractical or very
expensive due to deep frost or excavation through rock. An analysis
should be carried out to determine whether a shallow buried, insulated
pipe would be more economical and less of a maintenance problem than a
deep buried pipe.
6.5.2 Types of systems
6.5.2.1 Single-pipe recirculation. The single-pipe recirculation
system, whether above or below ground, is recommended as the best piping
-------
6-19
system for arctic conditions. This system consists of one or more
uninterrupted loops originating at a recirculating facility and returning
to that facility without any branch loops.
A well-planned recirculating system minimizes the length of
piping required which, in turn, minimizes energy losses. Recirculation
eliminates dead ends and any possibility of stagnant water or freezing.
The system also allows positive simple control of water distribu-
tion. Flow and temperature indicators on the return lines at the central
facility are all that is required. Under constant pumping the pretemper-
ing requirement is controlled by the supply and return temperatures.
Normally water is pumped out at between 4-7°C and returns at between
1-4°C, depending on local preference. In Greenland, temperatures are
held at 1°C, and down to 0.1°C return with electric heat tracing
and better sensing devices. However, this leaves a very low margin of
safety for repairs and is not recommended.
The obvious disadvantage is that, as the length of the loop
increases, the loss of service increases in case of a shutdown due to a
problem anywhere along the line. In practice this usually is not a
problem as the loop is extened annually to meet the normal growth rate
of the community, and at the completion of each phase, temporary short
loop links are installed to complete the loop that given year. The
following year these links are abandoned, valved off and the pipe left
empty. In the case of an emergency these abandoned links can be opened
up to reroute the flow of water and possible isolate the break. This
problem is also easily overcome on a short-term basis by bleeding at
appropriate points, especially when combined "mini service-centre
manholes" are used.
The single-pipe recirculation system is usually designed to
supply water in the normal "return" line as well as the supply line under
fire conditions. For this reason the return line does not decrease
drastically in size. A typical pipe size would be 250 mm out and 200 mm
return for a design community population of 2000population.
-------
6-20
The recirculating facility could be located at the point of
treatment or in a separate pretempering pumping facility, or a combinatio
of the two. Figure 6-10 illustrates an ideal town layout for this system.
The pretempering/recirculating and/or treatment facility is preferably
centrally located and the community is divided into a number of single-
looped sections. By planning community growth in a dense circular pattern
maximum efficiency can be made of this method of servicing. The worst
situation would be a long strung-out community with the facility at one end.
This usually ends up increasing pumping requirements and duplication of lines,
As noted in Figure 6-10, back-of-lot mains are preferred if
possible. In arctic communities under 3000 in population there are very
few, if any, paved roads. Snow accumulation and drifting is often severe
Loop links
1111^-7
From source
t
ruini
/
Recirculating
pumphouse
Water mains
t
D D
D O
FIGURE 6-10. LAYOUT AND LOCATION OF MAINS FOR SINGLE-PIPE RECIRCULATION
-------
6-21
and roads are cleared with a dozer. If the mains are placed in the
street (unpaved gravel roads), the manholes are subject to physical
damage. If the lines are shallow buried they are also subject to colder
ambient temperatures because snow clearing reduces insulation.
Placing the mains at the rear lot line not only avoids these
problems but reduces service line connections and permits service lines
of equal length on both sides of the main. With mains in the road
allowance, usually to one side, plus the normal 8 m requirement between
the front of the house and the road right-of-way, average service line
length would be 15 m on one side and 23 m on the other. The cost per
hook-up would be between $5000 to $7500 for the lot owner. With the
mains at the rear lot line, where houses can be placed as close as 3 m
from the lot line, an average service line length would be 6 m in either
direction at a eost per hook-up of approximately $2000. There is a
significant saving to the lot owner in this method of servicing which
encourages development of piped services.
"Back yards" are not used to a great extent in northern
communities. If houses are placed in a planned fashion similar to
southern temperate communities, the large area between the rear of the
houses could become wasted space. Depending on community attitudes,
this may be one more reason for placing mains at the rear lot line and
the houses as close to it as possible according to fire regulations.
(For more information see Section 2.)
A further advantage of mains located along the rear lot line is
that the manholes containing water line valves and hydrants, freeze
protection controls, etc., can be elevated in cylindrical shape
approximately 3 feet above grade. This results in easier access during
the winter as the immediate area around the elevated manhole is blown
clear of snow by local winds.
6.5.2.2 Water wasting - conventional systems. In this type of system
the water line network is layed out conventionally. To ensure flow at
dead ends, loops, and service lines water is bled off to sewers at a
number of areas.
-------
6-22
Disadvantages of this system are the inevitably high water
consumption and possibly high energy input. Consumption could go as high
as 4500 L/person/day (see Section 3).
This system should not be used where there is a limited water
source, where water requires expensive treatment, or where pretempering
of water is necessary as well as wasting. Possible use would be where a
relatively warm inexhaustible water source exists, allowing low initial
capital system cost through minimum pipe line lengths and pipe
insulation.
A further drawback of the system is that sewage with highly
diluted characteristics and large volumes becomes expensive to treat.
The City of Whitehorse, Yukon Territory, has such a water wasting system
with its incumbent sewage treatment problem. Whitehorse has the
advantage of being able to tap relatively warm groundwater, which reduces
operational costs.
6.5.2.3 Single pipe - no recirculation. This system is employed to a
great extent in Greenland and requires for its success complete coordina-
tion with town planning. High volume users, such as large apartment
blocks or fish processing plants are strategically located at the ends of
main lines to ensure a continual flow in the line without requiring a
return loop (see Figure 6-11).
High density users
Low density users
1
1 ,1 r_
1 c
t lij
1 11 «w —
L »LJ r"-
1 L_
mm
,1
1 1
P^IJ PI p FI
yl'W.'.'.1.'.'.*.1! f^v-j
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housinn
I
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/
jf
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r Ul I \\j\ lUUbt?
Apartment blocks
FIGURE 6-11. SINGLE-PIPE SYSTEM WITHOUT RECIRCULATION
-------
6-23
In Greenland, apartment blocks accommodating up to 1500 people
in one building are used for this purpose. In Canada, small community
sizes and the standard of housing make it impossible to implement this
type of system.
6.5.2.4 Dual pipe system. In this type of system a large supply line
and a small return line are placed side by side either in a utilidor or
in a packaged preinsulated pipe sysem (see Figure 6-12).
Utilidor
Foam insulation
Heat line supply
Heat line return
Main water supply-
Return water line-
Sewer-
Corrugated metal pipe
Packaged pre-insulated pipe
Return line
Main water supply line
Foam insulation
Outer covering
FIGURE 6-12. TYPICAL UTILIDOR AND PACKAGED PREINSULATED PIPE
-------
6-24
This system permits lines to be laid out in the normal manner.
rhe main is connected to the return line at the end of the line to ensure
circulation.
Service lines are taken off the main and return via the return
line to ensure circulation through the service connection by the pressure
differential between the two mains.
Heating of the mains can be provided either by pretempering the
main supply water or by utilizing separate heating lines.
Control mechanisms for this type of system tend to be elaborate
because varying consumption in different locations results in stationary
water in certain areas at certain times. Thermostatically controlled
solenoid valves are required on "short circuit" branches between two
lines at regular intervals to overcome this problem (see Figure 6-13).
To building
1
Return line
Watermain
Thermostatically operated valve opens
on demand to add heat to return line
FIGURE 6-13. DUAL PIPE SYSTEM
Even with these or similar control devices it is difficult to
ensure 100% movement of water at all times.
Other disadvantages of this system include:
- The greater number of lines used increases initial capital
cost and energy consumption is high due to the greater surface
area.
- The greater number of lines also increases the risk of line
breaks. However, ultimate flexibility is allowed in isolating
line breaks and keeping everything serviced.
-------
6-25
While this system is not recommended as a main system it does
have application as a sub-system to the single-pipe recirculation system
or in long pipelines where there are no take off branches, such as supply
lines from source to community, etc. The dual pipe system is often used
as a sub-system of a single-pipe recirculation system to service existing
houses in small areas that are difficult to service from the main loop or
where it is impractical to extend the main loop (see Figure 6-14).
From recirculating pumphouse
Pumphouse
Circulating pump
Electric heat traced
service line alternative
CL
O
o
c
'03
E
en
c
CO
Circulating pump
v
Dual main Sub-system
Small diameter
water pipe
To recirculating pumphouse
FIGURE 6-14. DUAL MAIN SUB-SYSTEM
The sub— system in effect becomes an elongated service line
servicing a number of houses. The unit at the end of the line will have
a circulation pump between the two lines to ensure that pretempering
water from the main loop is circulated through the line.
-------
6-26
6.5.3 Other methods
Other methods either still in the development stages or less
frequently used are as follows:
6.5.3.1 Small-diameter water distribution lines can be a more cost-
effective method of delivery for both small and large communities.
Small-diameter lines mean pipes of diameters from 50 mm to 152 mm.
If full fire flow and hydrants were used the lines would range from 152 mm
to 305 mm in diameter. The mode of circulation or main freeze protection
mechanism would be any one of the types previously described.
Small-diameter mains require more emphasis to be placed on fire
protection through building structure, building materials, etc. and the
use of sprinklers and hose cabinets in lieu of exterior hydrants.
One advantage of such a system is in the net energy savings.
Less surface area means less heat loss. There is also greater movement
of water in the pipes, making the system more reliable. The pipes can be
placed near or directly under houses due to lower capital cost,
practically eliminating service line problems.
Small-diameter piping systems are used extensively in Greenland
(see Figure 6-15), including the capital Godthab with a population of
12 000, and in Alaska, where 50 mm to 102 mm have been used by the U.S.
Public Health Service. In Greenland, in lieu of factory insulated pipe,
small diameter water mains and sewer lines are insulated and wrapped
on-site.
6.5.3.2 Intermittent or batch water supply has been proposed for small
communities as the most cost-effective method of distributing water
[2,3], Under this system, small diameter lines would go into and out of
each house in a series of continuous loops. Water would be distributed
at only certain times or on certain specified days. The lines would be
preheated, water distributed say for eight hours every Monday, Wednesday
and Friday, and then the lines would be blown out with air. The latter,
however, is not a very reliable method of dewatering lines.
In houses with existing 1136-L holding tanks, it would be the
homeowner's responsibility to open and close a valve on the water line to
fill his holding tank. Utilizing the existing storage capability in the
house in this manner is very attractive, especially for those communities
-------
6-27
FIGURE 6-15. SMALL-DIAMETER WATER MAINS
where water use is restricted by the lack of a continuous source, where
expensive storage reservoirs had to be built. In such communities it is
expensive to truck water; yet if fully-piped systems were used, increased
water consumption would either deplete the community's water source or
very large reservoirs would have to be constructed.
6.5.3.3 Summer line systems are useful in many communities where
permanent lines are not economically feasible. Local topography and
conditions, plus economics and convenience, may make uninsulated summer
lines desireable.
Such lines often take advantage of sources of water that allow
flow by gravity to the community. In other oases they are used in
conjunction with pumping systems. Eliminating the need for trucked water
for up to four months and using inexpensive above-ground lines reduces
overall costs. The summer lines can also be used to fill reservoirs for
winter use.
There are many different forms of summer lines but since they
are not unique to cold regions no further detail on this topic will be
given in this manual.
6.5.3.4 Lines with "flushing hydrants" are used to prevent sewer lines
from freezing up where relatively few hook-ups are on the end of a long
-------
6-28
line. A small amount of water (5 to 10 L/min) is bled into an end-of-
line sewer manhole. The bled water is syphoned into the sewer line in
predetermined batches, as shown in Figure 6-16, at regular intervals
determined by the flow of water and volume held in the manhole before the
syphon action takes place.
6.6 Service Lines
Service lines are usually incorporated as part of a service
bundle or utilidette. The common service bundle package used in arctic
Canada is as shown in Figure 6-12.
Double recirculation lines are recommended in all cases.
However, single-line systems with electric heat trace to prevent freezing
have been and are still being used by lot owners. The single-line system
uses a great deal of electric energy which, in isolated communities,
costs as much as $0.25/kWh. For this reason its use should be carefully
evaluated. Service lines entering the house must be isolated and/or
protected against movement.
Main elements of the service line are described below.
6.6.1 Method of circulation
The two most common methods are a pump inside the housing unit
and pitorifice circulation. Pitorifices must have a 0.61 m/s velocity in
the mains to operate properly. However, they cannot be used for service
line circulation if the lines are longer than 25 metres. Beyond this
length, a small circulation pump must be added in the house. Observed
head losses across pitorifices are given below. These measurements were
made in 1975 in the Kotzebue system to determine the head loss in the
main line loops due to the presence of the pitorifice fittings.
Loop
KEA
loop
uptown
loop
centre
loop
Length
(m)
12 300
11 055
8 250
Number of
Services
110
80
93
Head Loss/ Service
(pair of pitorifices)
0.31 kPa/pair (3.3 cm/pair)
0.32 kPa/pair (3.3 cm/pair)
0.34 kPa/pair (3.6 cm/pair)
-------
11000 Manhole
From water main
Valve and vacuum breaker
End of sewer manhole
(see detail)
Overflow and flush well
150 x 200 Tee wye
To sewer
200 to 150 Reducer
125 Siphon
I
NJ
VO
FIGURE 6-16. FLUSHING MANHOLE SYSTEM
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6-30
The measurement of head loss is valid for a 101.6 mm main line
flow of 6.75-7.5 L/s and 5 cm-1.9 cm pitorifices. A conservative design
loss of 6 cm per pair could be used.
The head losses in the pumphouse plumbing on each system must
also be calculated. These losses are substantial on most systems.
The main back-up freeze protection is an electric heat trace ther-
mostatically controlled from the housing unit, with high and low temperature
limits. If copper pipe is used as a carrier a metal band across the two
pipes at the mains can provide electric resistance thawing from within
the house as a second back-up system (see Figure 6-17 for details).
Another method is to insert a small-diameter probe into the
frozen pipe from the house and force hot water through it. (See Appendix F).
6.6.2 Materials
The standard service bundle includes a preinsulated 101.6 mm
diameter sewer line (65 mm water lines and a 18 mm conduit for pulling
in heat trace cable). The overall diameter is approximately 300 mm with
a 41 mil yellow jacket placed on the outside. If the service bundle is
exposed or used as an above-ground service, a metal outer jacket is also
recommended.
Details of above and below-ground service box take-offs are
shown in Figures 6-18, 6-19 and 6-20. Note details concerning service
valves and operating stems. These are a must in order to isolate a
service without digging it up and damaging the insulated hook-up box.
Other special precautions are taken, such as packing the valve box
assembly with low-temperature nonhardening grease to prevent water from
freezing around the mechanism and making it inoperable in winter. The
top of the valve box assembly is terminated about 10 cm below grade to
prevent damage by playing children, snowmobiles, etc.
6.6.3 Dual servicing
When adjacent housing units have a common owner, suoh as in
public housing, common services are often used as shown in Figure 6-21.
The water lines are so arranged that the supply goes into one house
through the circulating pump, out the return line to the main. In other
words, a small water loop connects two houses using the same service bundle.
-------
6-31
li
Dielectric couphngs-
Flortrir, heal tape
Service line from mam to building-
4/o Copper wire connected to both
18 0 copper service pipes to form
an electrical connection
A*l
i ~~
f~- . — • ^-^~^S-«.
\ I
Foamed in place
polyurethane
insulation
Pitonfice
Section A-A
FIGURE 6-17. WATER SERVICE LINE
300
Polvurethane insulation
Mam stop and access sleeve
Insulation cut and filled
with polyurethane foam
Metal jacket
180 Polyethylene supply
and return lines with
coupling and removable plug
100 0 Sewer service
and pipe
with grooved end
Polyethylene
nsulation wrap
150 0 Steel sewer 150 0 Steel watermam
FIGURE 6-18. ABOVE-GROUND SERVICE LINE
Filled with polyurethane
Section I
-------
6-32
Pipehanger
150 0 Sewer line with
75 mm insulation
and metal outer jacket
Service box
right access
150 or 200 0 Watermain
FIGURE 6-19. ABOVE-GROUND SERVICE LINE TAKE OFFS
100 x 101) mm Gt.fi,ir pOSt
Thaw cable
1500 Onto valve
Grade
Granular fill all around
^_ Cast iron extension bo* with
cover and foamed in place polyurelhane
50 mm Polystyrene plug
100If Polyethylene sleeve
Extension stem to underside of cover
Preformed or foamed in place
polyurethane insulation
Permagum seal between all joints
FIGURE 6-20. UNDERGROUND VALVE AND BOX
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6-33
To building
Circulating pump
SEE DETAIL
Common service bundle
Sewer line
Watermain
Foam insulated service bundle
Sewer cleanout
Water supply from mam
Return line to mam
FIGURE 6-21. DUAL SERVICING
This cuts the capital installation cost of the service line to
each house by approximately 1/3, and increases the reliability due to
greater consumption and dual circulation pumps on the one loop.
6.7
Materials of Construction
Described below are the most common materials used for piped
water distribution in northern regions. The materials are broken into
two categories. Category 1 materials are considered the best materials
for northern use. Category 2 materials should be used only if design
conditions allow their use in a safe dependable manner.
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6-34
6.7.1 Category 1 materials
6.7.1.1 Copper is mainly used in service lines because it can be
thawed using electric resistance. Type K only is recommended.
6.7.1.2 Ductile iron pipe can take shock loadings and has some
flexibility. Corrosion resistance is low and lining should be used as
with cast iron. It is very durable and fairly heavy. Its use is
recommended through rocky areas and/or where sand or gravel bedding
materials are not available. It is the best of the steel or east iron
pipes but relatively expensive (about $11.50/m for 10 cm). (C = 125).
Ductile iron with tyton or victaulic joints is also used where
bridge strength is required. This occurs when spanning piles above-
ground or where there is a possibility of isolated settlement below-
ground. Ductile iron also can be thawed using electrical resistance.
6.7.1.3 Steel pipe. The description for ductile iron also applies to
steel, except it is less corrosion resistant, somewhat lighter and more
flexible. The flexibility is hard on linings. Flexible epoxy linings
are being developed which should be more durable. Continuously welded
steel pipe is also used (especially in above-ground systems) to obtain
maximum spans between piles. It can be thawed using electrical
resistance. Expansion and contraction, including necessary thrust anchors,
must be taken into consideration.
Steel pipe can be connected using a method called "zap lock".
In this method two pipes of the same size with the ends bevelled to fit
into one another are hydraulically rammed one inside the other in the
field. A layer of epoxy cement is applied prior to the ramming process.
The resulting overlap of approximately 35 cm gives a joint that is stronger
than the pipe. This method is a good alternative to continuously-welded
steel pipe and can be carried out quickly in the field at cold temperatures.
6.7.1.4 Plastic pipe is just coming into its own. It is light (5.0 m
section of 10 cm diameter weighs about 12.8 kg), flexible, and has a
smooth interior (C = 150). Bedding is not as critical but still must be
done properly. It is easy to install but a little more expensive than
metal pipes. It has a higher coefficient of contraction and expansion
-------
6-35
than the other materials and this must be taken into account at joints.
The recommended type for northern regions is high molecular weight
polyethelene.
High density polyethelene (PE) is very flexible and impact
resistant. It cannot be threaded. PE is used widely for service lines
and main lines. Butt-fused PE pipe is used extensively in Canada for
water distribution and sewage collection lines. The pipe is insulated
with urethane and the outer pipe is also PE (the outer pipe joints are
heat shrink couplings). It is claimed that it can freeze solid and be
thawed using a heat trace line without rupturing or breaking [4].
Other materials are used where bridge strength is required.
Precautions must be taken if laid above-ground to account for large
expansion and contraction.
Pipe take-offs from fixed joints such as pumping stations must
be supported in case of ground settlement, which would cause unacceptable
stress on the pipe joint (see Figure 6-22).
density polyethylene pipe
Pipe support
FIGURE 6-22. SUPPORTED PIPE TAKE-OFF
6.7.2 Category 2 materials
6.7.2.1 Cast iron is probably the oldest (in use in Germany since 1455
It is relatively corrosion resistant if cement-lined and tar-coated, and )
providing the lining is not damaged before or during installation (damage
occurs easily). Unlined pipe should not be used. It is heavy and hard
to handle, but durable (6.1 m section of 10 cm diameter weighs 225 kg).
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6-36
6.7.2.2 Asbestos-cement pipe is being used extensively in temperate
climates. It must be carefully bedded or uneven loading will break it.
It is extremely corrosion resistant. It is relatively light (a 4 m
section of 10 cm diameter weighs about 30 kg), easy to install and is
nonmetallic. It is not costly (about $6.00/m for 10 cm diameter). It
has a smooth interior (C = 140) and retains it longer than the metal
pipes.
Asbestos-cement pipe should never be used for northern work in
buried conditions in soil subject to settlement or frost heave.
6.7.2.3 Plastic pipe. Polyvinyl chloride (PVC) pipe is the most
common type used in water mains. Type I is stronger; Type II is more
impact resistant but not rated for as high pressures. In cold climates a
Type I/Type II is used to gain part of the benefits of both. It can be
threaded and has the same cross-section dimensions as steel.
PVC pipe is manufactured in two basic types. First are the SDR
classes which have constant pressure ratings for all sizes throughout
each class. SDR is an abbreviation for sidewall diameter ratio. SDR 26
pipe, which is rated for 1103 kPa, is widely used for water mains.
Second are Schedules 40, 80 and 120, which roughly correspond to iron
pipe sizes and have more uniform wall thicknesses for different sizes
within each schedule. This sizing procedure results in small-diameter
pipes having much higher pressure ratings than larger pipes in the same
class.
Both of these general types are designed for pressure applications
and are used mainly for water systems. PVC pipe, designed specifically
for sewer use, has, in the past, been thin-walled and breakable. For
this reason, considerable quantities of the SDR 26 pressure-rated pipe
have been used for sewer lines in recent years. Non-pressure rated pipe
with thicker walls is now being manufactured under the ASTM designation
shown below for PVC sewer pipe and has proven very satisfactory. PVC
pipe is covered by the latest revisions of the following ASTM standard
specifications:
PVC pipe and fittings (SDR classes) - D-2241
PVC pipe and fittings (Schedules 40, 80 and 120) - D-1785
PVC sewer pipe and fittings - D-3034
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6-37
The design and installation practices recommended by the PVC
pipe manufacturer should be complied with. Many manufacturers have
compiled very good booklets covering PVC pipe and are quite willing to
provide these to actual or potential customers.
PVC pipe is not recommended for single-pipe buried installations
in permafrost.
Acrylonite-butadiene-stryrene (ABS) has high impact strength and
flexibility but has low mechanical strength (half that of PVC). It does
not become brittle at cold temperatures. ABS is being used primarily for
non-pressure drainage, waste and vent (DWV) work.
ABS has also been used by the U.S. Indian Health Service for
sewer mains, service lines and drain field installations. This pipe is
not as readily available as PVC in some sizes. In general, ABS pipe has
a higher impact strength than PVC in the more common types but it
requires a thicker wall to be equivalent to PVC in pressure rating.
Ratings and nomenclature for different types of ABS pipe are basically
the same as those for PVC. ASTM standard specifications covering ABS
pipe are as follows:
ABS pipe and fittings (SDR classes) - D-2282
ABS pipe and fittings (Schedules 40, 80 and 120) - D-1527
ABS sewer pipe and fittings - D - 2751
Design information is available from manufacturers and should
be followed closely. Again, ABS is not recommended for single-pipe
buried installations in permafrost.
6.7.3 Other types of pipe used
Regular or prestressed, reinforced concrete pipe is used,
usually for larger transmission lines.
Wood stave piping is good in cold regions because of its
insulation value. It is expensive and corrosion-free (except for the
wire). C = 140 and does not change with age. It is also able to
withstand freeze-thaw cycles without breaking.
6.7.4 Miscellaneous fittings
Joints - bell and spigot (rubber o-ring), mechanical joint,
dresser couplings, solvent welding, threaded, etc.
-------
6-38
Service lines are nearly all copper now but polyethelene is
being used more and more. The copper has the advantage of being
electrically thawable, but PE is considerably cheaper, easier to install,
and can withstand freeze-thaw.
Dresser or other type repair clamps should always be kept on
hand for all pipe sizes in the distribution system to repair leaks.
Valves should be AWWA approved types, rated for the pressure
under which they will have to work [5],
There are four basic groups of valves: globe, rotary (butterfly,
plug, etc.), slide (gate) and swing (check valves). Plug and ball type
valves are older; gate valves are most widely used now. All valves that
need frequent adjustment or operation should be furnished with a valve
box to the surface.
6.7.5 Insulation
Pipes of the materials noted above, when used in individual
piping systems, are normally insulated with high-density urethane foam
under factory conditions and covered with a 40-mil high-density polyethe-
lene jacket or steel, depending on the exposure of the material when
used. The factory-insulated pipes are shipped to the job site complete
with preformed half shells of urethane for the joints. Heat shrink
sleeves, or polyken tape is used to complete the joint in the field where
high-density polyethelene is used as an outer jacket. For pipes
insulated and covered with a steel jacket, a special metal jointing
section is used.
Except for appurtenances using urethane, insulation is not
normally done in situ because of the high cost and high labour
requirement. There is also a lack of end-product quality.
6.8 Appurtenances
6.8.1 Hydrants
6.8.1.1 Above-ground. Above-ground hydrant housings must be tailor
made to fit the particular design. They are generally of the Siamese
building wall hydrant type.
Figure 6-23 shows a typical above-ground hydrant with its
individually-designed insulated housing. The distance from the main is
-------
Removable preformed
polyurethane sections
Foamed in place polyurethane
Angle valve
Handwheel
Metal cap
Drip lip
C Siamese
hydrant
Galvanized pin
and chain
Insulation
Watermain
OJ
FIGURE 6-23. ABOVE-GROUND HYDRANT
-------
6-40
kept as short as possible so that heat conduction from the water flowing
through the main keeps the water in the hydrant from freezing. The
hydrant housing is painted fluorescent yellow.
6.8.1.2 Below-ground. A typical below-ground hydrant installation is
shown in Figure 6-24. The hydrant is normally on-line to minimize
possibility of freezing, with a frost-isolating gasket between the bottom
of the hydrant barrel and the tee into the main. The hydrant barrel is
insulated with 7.62 cm preformed polyurethane and placed inside a 50 can
diameter polyethelene series 45 pipe sleeve. The cavity between the
sleeve and the insulated barrel is filled with an oil and wax mixture to
prevent damage to the hydrant due to frost heave.
Isolating valves are normally put on either side of tee into the
main to allow for hydrant replacement or repair.
An appropriate mixture of propylene glycol and water of a grade
acceptable for potable water systems is pumped into the empty hydrant to
prevent the hydrant from freezing. After use, the hydrant must be pumped
out and recharged, since permafrost conditions may prevent self-draining.
6.8.2 Valves
Above and below-ground valves are basically the same, with the
exception of the valve box and operating stem details. Typical details
for such installations are shown in Figures 6-19 and 6-20.
Again, foamed-in-place polyurethane insulation is used with a
series 45 polyethelene sleeve over the operating stem filler, similar to
hydrants. Valves generally used for buried installations or where the
valve is completely insulated are nonrising stem-gate valves. In other
situations, sueh as in manholes, any appropriate valve can be used.
6.8.3 Metering
Standard meters are used to monitor flow in the distribution
system, including magnetic flow meters, in-line gear meters, and orifice
pressure differential recording graph meters.
Both the supply and return lines must be metered in circulating
systems with one or more loops. The difference gives the daily consump-
tion. Under fire conditions, a reverse flow meter or bypass is required
on the return line.
-------
6-41
Fire hydrant
Permagum seal
Isolating gasket
Metal cap
Grade
500 0 Polyethylene series 45 pipe sleeve
Oil and wax mixture filled to metal cap
75mm Preformed polyurethane
Shrink sleeve
50 mm Polystyrene bottom plug
Insulation
Watermain
Field applied polyken tape
Field applied sealant on insulation surfaces
FIGURE 6-24. BELOW-GROUND HYDRANT
-------
6-42
Most northern communities are relatively small. This means the
fire flows are as much as 10 to 15 times greater than the average flow.
In this case an orifice plate meter which is satisfactory for fire flows
will give unsatisfactory results under normal conditions. If it gives a
satisfactory graph under normal conditions then the orifice plate is such
that it restricts flows during a fire situation. Both magnetic flow
meters and gear-driven meters are very expensive for large diameter pipes.
In most instances, the large diameter supply pipe flow is diverted
through a small pipe through one of the latter two meters, and then back
to the larger supply size pipe. During fires the meters are completely
bypassed and flow is directed through the large supply lines.
6.8.4 Manholes
Manholes for both water and sewer requirements have been
constructed of a number of materials. Common types are:
- concrete,
- corrugated metal, and
- welded steel.
All of these have varying means of insulation.
The main problems in the past with manholes were that they were
too small, leaked excessively, or were subject to damage. One
alternative which evolved in the Northwest Territories is the manhole
shown in Figure 6-25, known as the "mini service-centre manhole".
The manhole shown in Figure 6-25 is a comprehensive one showing
both water and sewer lines as well as a hydrant, but the same basic
design is used for any situation. The interior layout and size are
designed to fit the requirements.
The basic concept is that all necessary day-to-day maintenance
of the distribution mains can be carried out in a climate controlled
environment. This includes maintenance of water line valves, hydrants,
heat trace power point, and sewer cleanouts.
Some of the features of such a manhole for northern work are:
Hydrants - Standard hydrants can be used and operated in
the normal manner.
-------
6-43
Concrete
manhole
Foam insulatior
FIGURE 6-25. MINI SERVICE-CENTRE MANHOLE
-------
6-44
- One isolating valve plus valve boxes and operating
stem extension are eliminated, reducing
installation cost.
- Replacement is easier; no digging is required.
- Relatively fool proof compared to glycol filled
hydrants.
Main valves - These are placed in manholes giving easy access
for operation or replacement and eliminating
valve boxes.
Manhole
Structure - The manholes are well insulated for energy
conservation
- They are large: minimum size 1.2 ttr depending
on interior fittings.
- All exposed surfaces are metal or concrete:
relatively vandal-proof and maintenance-free.
Power Point/
heat trace - Heat trace lines and control points are terminated
in the manholes. Replacement heat trace lines can
be pulled in from one manhole to the next.
- A thermostatically controlled electric heater
keeps the temperature above freezing.
- There is an electric plug for lights and small
power tools.
Sump pump - The sump pump is located in a prefabricated steel
sump pit set in the concrete base. The pump comes
on automatically if water from a used hydrant or
groundwater enters the hydrant and pumps through
a back flow preventer into the closed sewer line.
Sewer
cleanout - Closed sewer cleanouts are provided in the manhole;
covers have rubber gaskets so excess pressure can
be detected.
-------
6-45
6.8.5 Alarms and safeguards
Alarms and safeguards are a very important part of any system.
Flow alarms are a necessity in any circulation line to warn of stopped
circulation.
Low heat alarms are needed to warn of impending freeze-ups.
Flow meters are especially important to adjust flow in the return
circulation loop.
The alarms should be wired to the operator's house and be loud
enough at the pumphouse to wake someone and get them there to check out
the trouble. Alarms must be tested at least weekly to be sure they are
operational. A central control panel should be provided either in the
operator's house or the pumphouse.
6.9 Backup Freeze Protection Mechanisms
The main backup freeze protection mechanisms are:
- heat trace systems,
- thaw wire electrical resistance systems,
- steam or hot water thawing.
6.9.1 Heat trace systems
This is the standard back-up system used in most piped water
distribution systems. While it is effective, both the initial capital
cost and operating cost for this type of insurance are substantial. The
cost of installing heat trace systems is approximately $30/m of line,
including material and labour for the overall system.
Constant monitoring must be carried out on such electrical
systems if they are to perform as intended. If the controlling thermo-
stats are not working properly or the sensing bulbs are in the wrong
location, either too much electric energy will be expended at great cost
or it will fail to do the job when required.
Easy replacement of heat trace lines should be a standard
feature of any system. The heat trace normally used is the constant watt
per foot type placed in a conduit or channel next to the pipe with or
without heat contact cement. Common wattages used are 2.5 watts per foot
for service lines and 4 watts per foot for main lines. This method of
-------
6-46
placement of heat trace lines is relatively less efficient on plastic
pipes. In Greenland and Northern Scandanavia the heat trace is placed
inside plastic pipes.
Care must be taken to ensure the conduits are sealed. Otherwise
they will allow groundwater to enter the electrical system and manholes.
6.9.2 Thaw wire electric resistance systems
This system can only be incorporated on piping materials that
will pass an electric current, such as copper and steel. A current is
induced into sections of the pipe through strategically-placed thaw wires
by a portable electric generating unit. The resistance and resulting
heat thaws out the pipe.
The initial capital cost for this backup thaw system is low. It
is only used if the pipe is already frozen, as opposed to heat trace
systems which add heat before freezing takes place.
6.9.3 Steam or hot water thawing
This system uses a source of steam, such as a portable steam
jenny, or hot water introduced under pressure into the frozen pipe via a
suitable hose or tube to thaw out the pipe. This system can be used on
many types of materials. It is not recommended for use on plastic pipes
which could melt or be damaged if the procedure used is improper.
An example of the difference in the cost of heat tracing systems
versus steam thawing was noted in Norman Wells, N.W.T., where a portable
steam jenny was purchased in lieu of an electric heat trace system for
the welded steel pipe system. The difference in initial capital cost for
approximately 1800 m of mains was $95 000. This difference will increase
as more mains are installed because the steam jenney can be used for
other purposes.
The great difference in cost encourages careful consideration of
the alternatives to a heat trace system.
While heat trace systems appear to be the trend in back-up
thawing for single-loop reoirculation systems, better prefabricated
insulated pipe packages, and simple control and alarm systems warrant
re-evaluation of the justifications for a heat trace system.
-------
6-47
For thawing small service lines a power pump, a hot water
reservoir and small probe tube as described in Appendix F has proved most
successful and superior to other methods. Helpful tips, tables and
guidelines for thawing frozen water lines are also given in Appendix F.
6.9.4 Freeze damage prevention
The reduction of damage to water distribution pipes when
freezing occurs has been discussed by McFadden [6]. The use of a
diaphram at the last point to freeze in each section of pipe was
recommended as a good technique to reduce damage. The location of the
proper point can be selected and somewhat controlled by careful analysis
of the system and careful placement of additional insulation.
6.10 References
1. Government of the Northwest Territories, Department of Local
Government, "General Terms of References for an Engineering
Pre-design Report on Community Water and Sanitation Systems",
Yellowknife, August 1977.
2. James, William and Ralph Suk, "Least Cost Design for Water
Distribution for Arctic Communities", McMaster University
Hamilton, Ontario, May 1977.
3. James, William and Ralph Suk, "Design Examples: Least Cost Water
Distribution Systems for Pangnirtung and Broughton Island, N.W.T.",
McMaster University, Hamilton, Otario, May 1977.
4. O'Brien, E. and A. Whyman, "Insulated and Heat Traced Polyethylene
Piping Systems - A Unique Approach for Remote Cold Regions", In:
Utilities Delivery in Arctic Regions, Environmental Protection
Service, Environment Canada, Report No. EPS 3-WP-77-1, Ottawa,
1977.
5. Edwards, J. "Valves, Pipes and Fittings", Pollution November 1971.
6. McFadden, T., "Freeze Damage Prevention in Utility Distribution Lines
In: Utilities Delivery in Arctic Regions, Environmental Protection",
Service, Environment Canada, Report No. EPS 3-WP-77-1, Ottawa 1977.
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6-48
6.11 Bibliography
Alter, A.J., "Water Supply in Cold Regions", Cold Regions Research and
Engineering Laboratory, Monograph III-C5a, Hanover, New Hampshire, 1969.
Bohlander, T.W., "Electrical Method for Thawing Frozen Pipes", AWWA
Journal, May 1963.
Buck, C., "Variable Speed Pumping has Many Advantages", Johnson
Drillers Journal, May-June 1976.
Canada Department of Indian Affairs, "Handbook of Water Utilities,
Sewers and Heating Networks Designed for Settlements in Permafrost
Regions", Translated from Russian by V. Poppe, 1970.
Carlson R. and J. Butler, "Alaska Water Resources Research Needs for
the 70fs", Institute of Water Resources, Univ. of Alaska, Report
#IWR-39, Fairbanks, 1973.
Cheremisinoff, N. and R. Niles, "A Survey of Fluid Flow Measurement
Techniques and Fundamentals", Water and Sewage Works, December 1975.
Crum, J.A., "Environmental Aspects of Native Village Habitat Improve-
ment in Alaska", Standford Eng. Econ. Planning Report, EEP-46, 1971.
Dawson, R.N. and J.W. Slupsky, "Pipeline Research - Water and Sewer
Lines in Permafrost Regions", Canadian Division of Public Health
Engr., Manuscript Report No. NR-68-8, 1968.
Easton, E.R., "Reservoir Liners for Use in Arctic Water Supplies",
Arctic Health Research Centre, Fairbanks, Alaska, 1961.
Gamble, D. and C. Janssen, "Evaluating Alternative Levels of Water
and Sanitation Service for Communities in the N.W. Territories",
Canadian Journal of Civil Engineering. Vol. 1, No. 1, 1974.
Gardeen, J., "How to Fathom Liquid Level Sensing", Water and Wastes,
May 1976.
Gaymon, G.L., "Regional Sediment Yield Analysis of Alaska Streams",
Journal of the Hydraulics Div., ASCE, January, 1974.
Gordon, R., "Batch Disinfection of Treated Wastewater With Chlorine
at Less than 1°C", U.S. Environmental Protection Agency, Report
# 660/2-73-0, Fairbanks, Alaska, September, 1973.
Government of the Northwest Territories, Department of Public Works,
Equipment Specification No. 601, Municipal Water Delivery Truck
Hydraulic Drive, Yellowknife, NWT.
Grainge, J.W., "Arctic Heated Pipe Water and Waste Water Systems",
Water Research, Vol. 3, Pergamon Press, 1969.
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6-49
James, William, and A.R. Vieirn-Ribeiro, "Arotie Hydrology Project,
Baffin Island Field Program 1971 and 1972", McMaster University,
May 1977.
James, F., "Buried Pipe Systems in Canada's Arctic", The Northern
Engineer. Fall, 197§.
Kill, D., "Cost Comparisons and Practical Applications of Air Lift
Pumping", Johnson Drillers Journal, September-October, 1974.
Page, W.B., "Report on Tests Conducted to Design Pitorifiees and to
Measure Heat Losses from House Service Pipes at Washington State
College", Pullman, Washington, April, 1953.
Poss, R. J., "Distribution System Problems", AWWA Journal, Vol. 52,
No. 2, February, 1960.
Reiff, F., "Hydropneumatic Pressure Systems", U.S. Indian Health
Service, Anchorage, Alaska, 1967.
Ryan, W.L., "Design and Construction of Practical Sanitation
Facilities for Small Alaskan Communities", Paper included in 2nd
International Permafrost Conference Proceedings, National Academy
of Science, Washington, D.C., 1973.
Ryan, W.L., "Methods of Pipeline Construction in Arctic Areas",
U.S. Indian Health Service, Anchorage, Alaska, September 30, 1971.
Ryan, W. and J. Grainge, "Sanitary Engineering in Russia", AWWA
Journal, June, 1975.
Sanger, F.J., "Water Supply, Sewage Disposal and Drainage in Cold
Regions", U.S. Army Cold Regions Engineering and Research
Laboratory, Hanover, New Hampshire, 1964.
Simonen, E., "An Evaluation of Municipal Services in the Mackenzie
River Delta Communities", Univ. of Toronto, Masters Thesis with G.
Heinke, Toronto, Ontario, October, 1970.
Smith, D.W., ed., Proceedings Symposium on Utilities Delivery in
Arctic Regions, March 1976, Environmental Protection Service,
Environment Canada, Report No. EPS 3-WP-77—1, January 1977.
U.S. Department of Health, Education and Welfare, Division of Indian
Health, "Design Criteria for Indian Health Sanitation Facilities",
Anchorage, Alaska, 1972.
U.S. Environmental Protection Agency, "Manual of Individual Water
Supply Systems", Publication #24, Washington, D.C., 1962.
Watson, et al., "Performance of a Warm-oil Pipeline Buried in
Permafrost", Proceedings of 2nd Int. Permafrost Conference, Yakutsk,
USSR, 1973.
-------
SECTION 7
WASTEWATER COLLECTION
Index
Page
7. WASTEWATER COLLECTION 7-1
7.1 Sources of Wastewater 7-1
7.1.1 Domestic waste 7-1
7.1.2 Industrial waste 7-3
7.1.3 Public uses 7-3
7.1.4 Water treatment plant wastes 7-3
7.2 Individual Bucket Systems 7-4
7.2.1 Hauling containers 7-4
7.2.2 Disposal point 7-5
7.3 Vehicle-Haul with House Storage Tanks 7-7
7.3.1 Facilities at pick-up point 7-7
7.3.2 Hauling vehicles 7-9
7.3.3 Disposal site 7-12
7.4 Piped Collection Systems 7-13
7.4.1 Design considerations 7-13
7.4.2 Conventional gravity collection lines 7-15
7.4.3 Pressure sewage collection systems 7-21
7.4.4 Vaouum sewage collection systems 7-26
7.4.5 Other collection systems 7-30
7.4.6 Piped collection system materials 7-30
7.4.7 Pressure and alignment testing of sewer lines 7-30
7.5 Lift Stations 7-31
7.5.1 Types 7-31
7.5.2 Cold regions adaptations 7-31
7.5.3 Foree mains - 7-33
7.6 Building plumbing 7-33
7.7 Typical oonstruetion costs 7-34
7.8 References 7-34
7.9 Bibliography 7-37
-------
List of Figures
Figure Page
7-1 Waste Disposal Pit 7-6
7-2 Truck for Collecting Honeybucket Wastes - Barrow, Alaska 7-8
7-3 Tracked Sewage Pick-up Vehicle - Arctic Village,
Alaska 7-8
7-4 Individual House Holding Tank 7-10
7-5 Low Water Use, Foot Pedal Operated Toilet 7-10
7-6 Filling and Emptying Procedure for Holding Tank Pumpout
Trucks 7-12
7-7 Sewage Collection Lines on Piling - Bethel, Alaska 7-14
7-8 Small Utilidor Laid Directly on the Tundra Surface
Carrying Water, Sewer and Glyeol Lines - Noorvik, Alaska 7-14
7-9 Typical Sewer and Water Bedding Details 7-17
7-10 Sewer System Manhole 7-17
7-11 Sewer Cleanout Detail 7-19
7-12 Single Line Siphon 7-19
7-13 House Sewer Wall Connection 7-20
7-14 House Sewer Floor Connection 7-21
7-15 Typical Pressure Sewer Installation 7-22
7-16 Typical Pump-grinder Installation 7-22
7-17 Pump-grinder Characteristics 7-24
7-18 One-pipe Vacuum System Schematic 7-27
7-19 Vacuum Toilet 7-27
7-20 Grey Water Valve 7-29
List of Tables
Table Page
7-1 Characteristics of Wastewater Collection Systems 7-2
7-2 Types of Lift Stations 7-32
7-3 Unit Construction Costs (1977) 7-35
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7-1
7. WASTEWATER COLLECTION
Wastewater collection systems collect wastewater from users
and transport it to the sewage treatment facility or disposal point. The
sources of wastewater and types of collection systems and design para-
meters are presented in this section. As presented in Section 2, the
main types of collection systems are individual bucket haul, vehicle-haul
with house storage, and piped. Table 7-1 summarizes the characteristics
of wastewater collection systems.
7.1 Sources of Wastewater
The main sources of wastewater are domestic and industrial. In
the case of domestic waste, 100 percent of the water in northern areas
ends up as wastewater because there is very little lawn and garden
watering or car washing. This also applies for industrial or commercial
wastes unless local experience or actual measurements indicate otherwise.
An exception would be the case of a cold storage-fish processing opera-
tion or a cannery where a significant portion of the water may be used
for cleaning floors and equipment and is discharged directly to the ocean.
A contrary example would be the case where salt water was used for clean-
ing and discharged to the collection system. Infiltration and inflow
allowances must be made for buried lines in high groundwater situations
or where water wasting is practiced. These problems should be corrected
before sewers and sewage treatment plants are designed. Inflow and
infiltration studies should be performed so the decision can be made to
either correct the problems or design a plant to treat the dilute waste.
7.1.1 Domestic waste
Water use rates typical to cold regions were presented in
Section 3 and sewage design flows with peaking factors are presented in
Section 9. The values presented show that sewage flows can vary
considerably. They are lower in volume, and higher in strength, for
camps and facilities with low water use plumbing fixtures. Where water
is wasted during the winter to keep service lines from freezing, waste-
water volume can be extremely high and of very low strength. There is no
substitute for actually monitoring sewage flows, or at least water use
rates, before sewer or sewage treatment design is undertaken.
-------
TABLE 7-1. CHARACTERISTICS OF WASTEWATER COLLECTION SYSTEMS
TYPE
Gravity
SOIL
CONDITIONS
Non frost
TOPOGRAPHY
Gently sloping
ECONOMICS
Initial construc-
OTHER
Low Maintenance.
susceptible or
Slightly frost
susceptible with
gravel backfill-
ing material.
to prevent deep
cuts and lift
station.
tion costs high
but operational
costs low unless
mus t go above
ground or use
lift stations.
High health and convenience
improvements.
Must hold grades.
Flushing of low use lines may be
necessary.
Large diameter pipes necessary.
Vacuum
Most useful for
frost susceptible
or bedrock condi-
tions, but can be
used with any soil
conditions.
Level or gently
sloping.
Initial construc-
tion cost
moderately high
Operational costs
moderate
"Traps" every 100 metres.
Low water use.
High health and convenience
improvements.
Must have central holding tank for
each 30 to 50 services with additional
pumps to pump waste to treatment
facilities.
Can separate gray and black water.
Uses small pipes.
No exfiltration.
Pressure
Most useful for
frost susceptible
or bedrock condi-
tions, but can be
used with any soil
conditions
Level, gently
sloping or
hilly
Initial construc-
tion costs
moderate.
Operational costs
moderately high.
Low water use if low water use fixtures
are installed. High health and con-
venience improvements.
No central facility necessary — units
are in individual buildings.
Number of services not limited.
No infiltration.
Uses small pipes.
Vehicle-Haul
Year-round roads
must be available,
Level, gently
sloping or
hilly.
Initial construc-
tion costs low.
Operational
costs very high.
Low water use and moderate health and
convenience improvements.
Operational costs must be subsidized.
Individual-Haul
Used with any
soil conditions
but boardwalks
are necessary in
extremely swampy
conditions.
Level, gently
sloping or
hilly.
Initial construc-
tion cost and
operational costs
very low.
Low usage by inhabitants and thus low
health and convenience improvements.
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7-3
7.1.2 Industrial waste
Industrial waste output is usually seasonal in cold regions.
Canneries and cold storage wastes occur during the summer fishing season
only. Reindeer slaughtering and packing plant wastes have a high
strength and flow, but usually only last for a couple months during the
fall. The amount and strength of industrial wastes produced must be
estimated using information from temperate areas for similar facilities,
unless the facility can provide the information for their operation. The
kind and size of the solids present in an industrial waste may be a
factor in waste collection system design. Screening or comminuting may
be necessary before discharge to the sewer system.
7.1.3 Public uses
Nearly all communities will have schools and hospitals or health
clinics. Estimates of wastewater flows must be obtained for schools,
considering the number of students, the number of teachers living in
quarters, the type of facilities provided (i.e., swimming pool, flush
valve toilets or regular gravity flush toilets, urinals, shower facili-
ties), boarding student dorms, etc. With hospitals or clinics, the
number of beds and, again, the type of facilities provided should be
determined. It may also be necessary to consider incineration or other
special treatment of wastes that are dangerous to health. Another public
use waste would be that from laundromats. These wastes are not much
different from those from similar facilities in more temperate climates.
See Section 3 for estimating water use to be expected at public
facilities. The strength of the wastewater is a function of the type of
water distribution system.
7.1.4 Water treatment plant wastes
Wastes from water treatment plants must be estimated if they
cannot be measured. The highest flows, which would be from filter
backwashing, are usually known. They can be very sporadic (not usually
continuous) and may require a holding tank for flow equalization before
discharge to the collection system. Filter backwashing flows are low in
BOD but create a high chemical and hydraulic loading. Consider the
effect of the chemicals on the collection line materials. They can be of
-------
7-4
high pH and/or very corrosive. Consider electrolysis problems when
wastes are from a salt water distillation unit. This can usually be
reduced by correct grounding and non-conduction fittings in piping
systems. When plastic pipe is used corrosion and electrolysis are
usually not problems.
7.2 Individual Bucket Systems
With a collection system relying on the individual users to
bring their wastes to a disposal point, the important considerations are
the types of containers in which the waste is transported and the
facilities at the point of discharge.
7.2.1 Hauling containers
Containers used by individuals for transporting wastes will vary
from conventional oil drums to honeybucket pails. They should be
cleanable so they can be washed or steam-cleaned and disinfected for
reuse (see Section 13). The containers should be covered so the contents
don't splash out in the owner's house or throughout the community as they
are transported. The containers should be sized for the way they will be
transported. In many communities with no roads the children or women
will empty the honeybuckets. Larger containers can usually be used in
the winter because they can be carried on sleds. The summer is the
critical time because the swampy conditions around many coastal
communities will mean hauling by hand. In this case, the pail or bucket
should probably not be larger than 10 litres, which would weigh about 10
kg when full. If roads are present and individual vehicles can be used
year-round, larger containers may be desirable. In many smaller
villages, 20-litre containers are readily available because gasoline and
white gas are purchased in them. They are used for everything from
hauling water to patching holes in the roof. In larger communities,
individuals use pickups or trucks to transport oil drums filled with
honeybucket wastes to a disposal site. Individual honeybuckets in the
house are emptied into the oil drum which sits outside the house.
Sometimes the oil drum is emptied and returned to be refilled but
usually, unless cleaning facilities are available at the disposal site,
the drum is discarded with the waste.
-------
7-5
7.2.2 Disposal point
The disposal point must be designed to accommodate a wide
variety of container sizes and be convenient for people; otherwise the
wastes may not be deposited according to facility design. The disposal
point Gould be a landfill site, a facultative lagoon or pond, a waste
disposal "bunker", or a discharge point on the side of a building such as
a watering point or central facility (see Section 13) where the waste is
then transported to a treatment facility by pipes.
Where honeybucket wastes are dumped at a landfill site they
should be covered daily to prevent children, dogs, and birds from getting
into them.
If the wastes are deposited in a lagoon or pond the dumping
point should be designed to prevent erosion of the lagoon dykes and yet
allow for easy access so the waste doesn't end up all over the dykes
instead of in the lagoon. A platform with a hole out over the water is
satisfactory. A major problem with lagoon disposal is the plastic bags
which are often used as liners in honeybuckets. They are not bio-
degradable and should not be deposited in the lagoon. It will be
necessary to empty their contents into the lagoon and then deposit the
bags at a landfill or burn them.
Waste disposal pits are constructed by cribbing a hole in the
ground, similar to a cesspool and covering it with a platform containing
a disposal hole covered with a fly-tight, hinged lid (Figure 7-1). When
the old pit is full the platform is removed and the bunker is covered
with the material excavated from the new pit. Most of the liquid portion
of the honeybucket wastes will seep out when the surrounding ground is
thawed. As with privies, waste pits are not a desirable form of waste
disposal if the soil is frozen fine grained silts or when there is a high
groundwater table. More modern methods such as sewage treatment plants
or lagoons are desirable, but the pits at least reduce the serious health
problem of having the honeybucket wastes dumped over a river bank or
around the houses.
The most satisfactory disposal for honeybueket wastes would be
at a central facility or watering point where the wastes are a small part
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7-6
-
FIGURE 7-1. WASTE DISPOSAL PIT
of the total waste load to the facility. The treatment would be
accomplished by one of the methods discussed in Section 9. A fly-tight
closeable box, which is convenient to use, should be provided on the
outside of the building. It must be vandal proof and capable of being
thoroughly washed down and cleaned daily. Above all, it must be
aesthetically acceptable and easy to use; otherwise, it will not be used.
Disposal points must be centrally located to all dwellings or
their chances of being used regularly are small. The distance that
individuals will haul wastes varies with many factors. Two of the more
important considerations are training and education of the users, and the
ground conditions over which the wastes must be hauled. Experience
indicates that the number of individuals that utilize a disposal point
starts dropping off considerably when the distance exceeds 200 metres.
Also, the people tend to haul longer distances in the winter because in
most communities, it is easier to get around and snowmobiles can be used.
An extensive education program is invaluable in promoting the use of a
disposal point with individuals hauling their own waste.
The type of waste dumped at a disposal point eould be an impor-
tant consideration in treatment plant design even though the quantity (by
-------
7-7
comparison to the facility wastes) may be small. The waste quite often
contains a high concentration of deodorizers such as formaldehyde and
phenols, which could affect biological treatment processes. It also may
contain plastic bags and other solid wastes and will be very high in BOD
(up to 1000 mg/L) and low in hydraulic loading.
7.3 Vehicle-Haul with House Storage Tanks
Community-haul sewage collection deals with the collection of
wastewater from each dwelling and its transportation by a community or
contractor-operated tracked or wheeled vehicle to a treatment and/or
disposal facility.
7.3.1 Facilities at pick-up point
The facilities at the individual user's dwelling or building can
vary from simply emptying a honeybucket (as discussed under individual-
haul above) into a tank on a truck (Figure 7-2), to a holding tank within
the building from which the wastes are pumped into the collection truck.
If the facilities in the building consist only of honeybuckets,
the same considerations listed under individual-haul would apply.
However, most modern vehicle-haul systems consist of a sewage holding
tank located on or beneath the floor of the house into which the
household wastes from sinks, lavatories, and toilets drain by gravity.
The tanks are then emptied into the collection vehicle (Figure 7-3) by
pumping.
The efficiency and operational costs of this type of collection
system are dependent partly on the sizing of the holding tanks. For most
circumstances, tanks should be around 1000 litres, but at least 400
litres larger than the water storage tank provided [1,4]. In Canada,
household tanks as large as 4500 litres have been used and it is common
practice to make the sewage holding tank up to twice as large as the
water storage tank. The size of the collection vehicle and reliability
of the service should be considered in sizing wastewater storage tanks.
It is also important to provide the structural support in the house
required to carry this additional load. The tank must be constructed
with a large manhole with removable cover so it can be cleaned and
flushed out at least yearly. It must be well insulated, kept within the
-------
7-?
FIGURE 7-2. TRUCK FOR COLLECTING HONEYBUCKET WASTES
- BARROW, ALASKA
FIGURE 7-3. TRACKED SEWAGE PICK-UP VEHICLE
- ARCTIC VILLAGE, ALASKA
-------
7-9
heated portion of the building and/or heat must be added using heating
coils or circulating hot water to prevent any ice formation. In some
instances, the holding tanks have been buried in the ground beside or
beneath the houses (Figure 7-4). In permafrost areas this is not
satisfactory and it is even necessary to add heat in areas where the tank
is buried in the active layer. The tanks must be placed so they are
emptied from the outside of the house.
The hose connections should be of the quick-disconnect type and
be a different size than that of the water delivery hose, to eliminate
the possibility of a cross-connection. The pumpout connection at the
building must be sloped to drain back into the tank after pumping so
sewage does not drain outside the house or stand in the line and freeze.
The tanks must be vented into the attic or outside to allow for air
escape or supply as the tank is filled and emptied. The same considera-
tions should apply to this vent as are discussed at the end of this
section under building plumbing.
With any haul system, low water use plumbing fixtures (Figure
7-5) are necessary to reduce water usage.
7.3.2 Hauling vehicles
The type of vehicle used depends upon the conditions at the
site. Tracked vehicles should be avoided if at all possible because of
the much higher capital, operating and maintenance costs, and slower
speed compared to rubber-tired vehicles. Typical costs of the vehicles
themselves are presented in Section 6 and Appendix D. Instead of tracked
vehicles, four-wheel drive trucks with floatation tires can be used where
snow drifting and poor roads are prevalent. Where there are no roads tracked
vehicles may be necessary.
Vehicle-haul systems have higher O&M and replacement costs than
piped systems, and the vehicles have a short useful life (see Section
2.6.2).
The vehicle must be equipped with a tank, pump and hoses to
contain and extract the wastewater (sample specifications are shown
in the Appendix E). For collecting honeybucket wastes, the most prac-
tical tank is a half-round or round shape with a large manhole with a
hinged lid on the back in the flat cover (see Figure 7-2). The flat top
-------
-------
7-11
allows for a lower emptying point. Steps are provided on the side so the
honeybuckets can be carried up and emptied into the tank. The trucks should
be kept as small and maneuverable as practical to get around to the houses.
Presently, tanks of 1000 to 5000 litres are used in small communities. The
tank should be capable of being dumped at the disposal site unless the
contents are to be pumped into a sewage treatment plant. At the rear, a large
valved outlet pipe of at least 200 cm (8 inches) in diameter is provided which
can be opened to empty the tank. A small heater may be needed to keep the
short pipe and valve from freezing. The truck exhaust can also be routed to
keep this valve warm and eliminate the need for a heater. A full opening,
non-rising stem gate valve has proven best for this application as it must be
capable of passing solids such as plastic bags.
The tanks on vehicles to
be insulated or enclosed in heated
be used with a pumpout system may have to
units on the backs of the vehicles (see
Figure 7-3). These units will include the tank, pump, piping, and connection
hose. The size of tank needed will depend primarily on the distance to the
disposal site and the sizes of the tanks in the houses [1]. Larger tanks will
reduce operating costs, particularly when the disposal site is distant. Size
and weight of the vehicle, and thus the tank will be limited to the layout of
the community and the condition of the roads. The truck must maneuver close
enough to the houses to pump out the tanks in a reasonably short time.
The number of trucks needed in a given community will depend mainly
on the number of buildings to be serviced and volume of wastewater to be
collected [1,4]. Two methods of emptying the house tanks are being used. With
one, a pressure tank is used on the vehicle. The tank is held under a vacuum
using a small compressor and a three-way valve. The contents of the house
tank are withdrawn into the truck tank under vacuum. At the disposal point
the valve is turned to pressurize the tank, forcing the wastewater out (see
schematic in Figure 7-6). The advantages to this method are that a compressor
is used instead of a pump, and there are no pipes containing sewage, which
could freeze. The other method is similar except that sewage pumps are
-------
7-12
-Clutch handle
Negative pressure port
Vent to
| atmosphere
Valve handle
Positive pressure
relief valve
Fill and
discharge hose
Positive
pressure port
Pressure gauge
negative and positive
• Butterfly valve open
while filling holding tank
LJLJjl
Wastewater holding tank
on pumpout vehicle
Butterfly valve open
while emptying holding tank
Filling holding tank by air suction
FIGURE 7-6. FILLING AND EMPTYING PROCEDURE FOR HOLDING TANK PUMPOUT TRUCKS
Emptying holding tank by positive
air pressure
used instead of a compressor and the vehicle tank does not have to be
pressure rated. The suction hose must be long enough to extend from the
house to the most convenient parking place for the truck. It should be
at least 7.5 cm in diameter and kept on a reel so it can be rolled up
inside the heated compartment on the truck. It must also be rugged
enough that it can be dragged behind the truck between houses, and be
flexible at low temperatures.
7.3.3 Disposal site
The disposal point should be in a heated building with a "drive
through" design to make the unloading time as short as possible. The
building should also provide heated storage for the vehicles while not in
use or when they're down for repairs. Where the disposal point is at a
landfill or lagoon, a ramp or splash pad or something similar should be
provided to prevent erosion and still allow the vehicle to deposit the
wastes well within the lagoon or landfill. The same problems with
plastic bags will be present as were discussed under individual-haul.
The building in which the vehicles are stored and/or emptied
should also be equipped with water for flushing and cleaning the tanks.
Extreme care should be taken to prevent any cross-connections.
-------
7-13
7.4 Piped Collection Systems
There are several variations of piped sewage collection systems.
Normally, a conventional gravity system has the lowest life-cycle cost
and should be used whenever feasible. However, the layout of the site
and/or the soil conditions may make a vacuum or pressure sewage collec-
tion system necessary. An additional advantage of a gravity system is
that a freezeup seldom causes pipes to break. The freezeup is gradual
and in layers, in contrast to pressure lines which are full when freezing
takes place.
7.4.1 Design considerations
When soil conditions do not allow burying collection lines (as
discussed in Sections 2 and 8), they must be placed on or above the
surface of the ground. In most locations, the topography and building
layout would dictate above-ground lines on pilings (or gravel berms) to
hold the grades necessary for gravity sewage flow. Above-ground lines
are undesirable because of transportation hinderance (see Figure 7-7),
high heat losses, blocked drainage, vandalism, and the cluttered look
they create within the community (see Section 8). It may be preferable
to use a pressure or vacuum system so that the lines can be placed on the
ground surface (see Figure 7-8), to minimize the above problems.
Sewage collection lines may be placed in utilidors (see Section
8) with other utilities, depending on the local circumstances. Utilidors
cost between $600 and $1700 per metre to construct, depending on the
utilities included and the roads to be crossed (see Section 8). Buried
pipelines cost (per pipe) between $100 and $300 per metre to install,
depending on the excavation conditions. Above-ground pipeline costs
depend on the foundation required. If they can be layed directly on the
ground surface they cost $50 to $100 per metre, but if they have to be
placed on pilings the costs could run as high as $250 per metre.
Assuming the same design, heat losses, and thus O&M costs, of above-
ground facilities are nearly three times as high as for the same line
placed below-ground because of the greater temperature differential
between the inside and outside of the line. Section 2 includes a more
in-depth discussion of the advantages and disadvantages of above or below
ground facilities.
-------
7-14
!•*•
m
i^r^l
Jfi i_ .» "tyfc,. <-» .'*"
A ^ **z^^ .^^si^V-> -
>^v..
• A
"•», 2*-•»"-.
•a. *** „ o
FIGURE 7-7. SEWAGE COLLECTION LINES ON PILING
- BETHEL, ALASKA
FIGURE 7-8. SMALL (0.4 m x 0.5 m) UTILIDOR LAID DIRECTLY
ON THE TUNDRA SURFACE CARRYING WATER, SEWER
AND GLYCOL LINES - NOORVIK, ALASKA
-------
7-15
Sewage temperatures are also an important design consideration.
In camps or communities where the individual buildings have hot water
heaters, sewage temperatures usually range between 10 and 15°C.
Where hot water heaters are not used and any hot water must be obtained
by heating water on a cook stove, sewage temperatures range from 4 to
10°C. A greater percentage of this heat will be lost between the
users and the point of treatment with a gravity system than with a
pressure or vacuum system. The sewage is longer in transit and there is
air circulation above the sewage in the pipes because they are not
flowing full. It is often necessary to dump warm water at the ends of
little-used laterals in a gravity system to eliminate freezing problems
caused by the lines slowly icing up. Also, a greater percentage of the
heat will be lost if the lines are above ground. Sewage heat losses will
not vary considerably from summer to winter with buried lines, but there
can be a considerable variance in above-ground lines. (This is discussed
in detail in Section 8.) Thus, the worst condition is to have gravity
sewage collection lines placed above-ground.
7.4.2 Conventional gravity collection lines
If lines can be buried and the layout of the site is sloping a
gravity sewage collection system will have lower O&M costs than other
types of systems. Initial construction costs will usually be lower
unless there is considerable rock to excavate. Costs for rock excavation
range between $50 and $75/m3 in the N.W.T. (1977).
The most important design consideration with gravity sewers is
the minimum grades necessary to ensure adequate velocities in the pipe-
lines. The following minimums should be used with stable ground condi-
tions (not frost-susceptible):
a) Main collection lines
Nominal
Pipe Size
(inches)
6
8
10
12
Minimum Slope
(percent)
0.6
0.5
0.4
0.3
-------
7-16
14 0.22
15 0.17
b) Building service lines
4 or 6 1.0
If soil stability is unsure (i.e., a small amount of settling or
heaving is likely), use a minimum slope of one percent for all collection
lines and backfill with non-frost susceptible sand or gravel at least 30
cm at the bottom and sides of the pipe (Figure 7-9). The 4-inch service
lines should be placed the same way with a two percent minimum slope.
Higher slopes than those above should be used if possible because the
longer the sewage is in the collection system, the more heat it will
lose. In small communities minimum sewage collection line sizes could be
6 inches instead of the normal 8 inches.
Lines should be placed deep enough to prevent damage from
surface loadings and the possibility of future expansion should be
considered. A minimum of 0.7 metres of bury is usually recommended but
less could be allowed in communities with no roads or vehicles. Other
depth of bury considerations are given in Section 15.
Storm water should not be included in sewers in cold regions.
It can be cold, lowering wastewater temperature, it overloads treatment
facilities hydraulically, and it usually contains sand and grit which
deposits in collection lines. Insulated pipe should always be used
unless lines can be buried well below the active layer and not in
permafrost.
In addition to the steeper slopes listed above, provisions
should be made to readjust the slope of a line if it traverses an area
where movement is likely. With lines on piling this has been done by
placing blocks between the piling and the pipeline, acting as shims.
They can be removed or added to readjust the slope. If the lines are in
a utilidor they can be suspended from the utilidor roof with adjustable
turnbuckles or placed on adjustable yokes or supports.
Manholes require protection from frost heaving or jacking forces
by use of plastic film to break the soils bond to the manhole (see Figure
7-10). They should also be insulated with a minimum of three inches of
styrofoam or urethane around the outside. The insulation reduces heat
-------
7-17
Hand tamped backfill
Bedding gravel or sand
to top of pipe
Pipe
Variable
Compacted
backfill
I: 100
FIGURE 7-9. TYPICAL SEWER AND WATER BEDDING DETAILS
150 Minimum
3 Wraps of 6 mil polyethelene film
1100 Corrugated aluminum pipe
Field foamed urethane
Concrete
Corrugated metal pipe
Variable
25
Grout seal
Field cut bore to fit pipe size
_
'oarnecl urethane
50 x 100 Support bolted to culvert with 50 x 50 angle clip
j^^cfrrrVTrV^^'^'^^ncreteT^^'l 50 Mln /;;^Kjp-,,.,,,,-,-,,,:,,,. ,,,,..-
FIGURE 7-10. SEWER SYSTEM MANHOLE
-------
7-18
losses and provides an additional safety factor against soil bonding and
frost jacking. An insulated frost cover to further reduce heat losses
should be provided inside. Manholes must have a firm foundation to
prevent settlement. This could mean pilings under the manhole or, at
least, over excavation and backfill with gravel. The invert should be
poured over insulation to reduce heat loss downward which could thaw
unstable permafrost and cause settlement.
Conventional pre-cast concrete manholes are very expensive to
ship and install in remote northern areas. Bolted corrugated aluminum
manholes can be used in nontraffic situations. They can be nested during
shipment and air freighted in small planes. Manholes should be placed
every 90 m or at any changes in grade or alignment. To reduce heat
losses, 107-om diameter manholes are used as a minimum in aretic areas.
Also, solid manhole covers without holes should be used so that surface
water does not enter the manhole. The lids should be looked down to
prevent the deposit of rocks and garbage in the manholes. Gravity sewer
lines should be thoroughly flushed out each summer, ideally when the fire
hydrants are being cleaned and flushed.
Cleanouts, as they are known in temperate climates, should be
used with caution. They are susceptible to frost jacking and hard to
protect (see an example in Figure 7-11). In place of a cleanout on a
sewage collection line it is better to use a conventional manhole.
A special manhole has been developed in the N.W.T. that contains
hydrants and valves for the water line and an air tight cleanout on the
inlet and outlet sewer lines for rodding and flushing. (See Section 6).
One must be sure not to create a cross-connection with a manhole
containing water line appurtenances.
As mentioned earlier self-flushing siphons may be required at
the end of long, little used laterals. They can be set to dump a given
quantity of warm water at different intervals. The slug of warm water
traveling down the sewer lines will eliminate any glaciering which may
have built up because of slow trickles of water from normal use. The
flushing also scours solids which may have been deposited because of low
flows. They should not be used unless absolutely necessary as they waste
water and create an additional O&M cost. It is better to lay out the
-------
7-19
'::?f:-\:::r:?-^^
.\- . ••'.'. • 150 to 300 if under travelled roadway
''
Cast iron frame
and bolt-down cover
with lift hole
Gravel backfill;;/?
Urethane insulation
Corrugated metal pipe
Wrap with 3 layers of
6 mil polyethelyne film
FIGURE 7-11. SEWER CLEANOUT DETAILS
Sewer pipe
11000 Manhole
From water main
Valve and vacuum breaker
..i-BW^ff&j^/j^&V^jjI^^/y
Overflow and flush well
150 x 200 Tee wye
To sewer
200 to 150 Reducer
125 Siphon
FIGURE 7-12. SINGLE LINE SIPHON
-------
7-20
sewer system so there is at least one large user near the end of each
lateral to eliminate the need for flushing. They can be constructed in a
building or in a manhole as shown in Figure 7-12. Again, oare must be
taken not to create a cross-connection between the water and sewer systems.
Figures 7-13 and 7-14 show typical service line connections to a
building for a cold region gravity sewage eollection system. They should
slope at least one to two percent to the oolleetion main, depending on
soil stability. Of the two examples shown, the method of going through
wall is preferable to going through the floor. The former will allow for
more movement of the house without damage to the sewer service line and
also permits all house plumbing to be kept above the house floor (this
will be discussed later).
The preferred method for thawing sewage eollection lines is to
push a small diameter plastie line through the frozen line while
circulating warm water. A complete discussion of thawing lines is
contained in Appendix F.
Sewage lift stations will be discussed later in this section.
They can be an important part of a gravity system.
Wood box with removable
lid screwed on with
wood screws
Filled with polystyrene
or fiberglass insulation
To building sewer
150
Minimum
Hose clamp
90 0x 500 Flexible hose
75PVC
100 x 75 Reducing bell coupling
Band
Filled with polystyrene
or fiberglass insulation
Flexible rubber dram housing
Band
Approximate ground line
__^^-.
' o'-;~
Corrugated metal pipe
filled-in or smooth to
reduce frost jacking
FIGURE 7-13. HOUSE SEWER WALL CONNECTION
Box-
-------
7-21
To building sewer
Detail
Plug
Calking
Building floor
Flexible rubber drain housing
Filled with polystyrene
or fiberglass insulation
Approximate ground line
.. .-. •. *
•o. :-o- • :
All temperature grease
900 Flexible rubber hose
75 PVC
100x75 Reducing bell coupling
Band
r- v; ••-..-
Corrugated metal pipe
(Filled-in or smcfe'dt^l
to reduce frost • „
jacking) To Sewer mam
FIGURE 7-14. HOUSE SEWER FLOOR CONNECTION
1 00 PVC
7.4.3 Pressure sewage collection systems
If soil conditions and community layout make a gravity
collection system not practical a pressure or vacuum system may be
considered. Pressure sewage collection systems usually have sections
that operate under gravity, and vice-versa. A small pump-grinder unit in
or near each building provides the motive force for the pressure system
(see Figures 7-15 and 7-16). The largest advantage is that it is not
necessary to maintain grades. Pipelines or utilidors do not have to be
on piling or up off the ground. They can be at the surface or buried and
small movements due to frost heave or thawing will not affect operation.
There can be no problems with infiltration of groundwater because the
lines are under pressure; however, a leak in the sewer line, if not
repaired, could contaminate other lines within a utilidor. Construction
costs would probably be lower than either a gravity or vacuum system, but
O&M costs would be greater than for a gravity system because of the pump-
grinder units in each building. Smaller collection lines can also be
used with a pressure system and normal elevation differences throughout a
community will not affect operation. Pressure collection lines can be
-------
7-22
Building gravity sewage piping
Storage tank —^fr
Pump-grinder —^<
On-off level sensor
Overflow level sensor
Drainage field
Existing septic tank
I 1
FIGURE 7-15. TYPICAL PRESSURE SEWER INSTALLATION
.
-^v'V:-.:l3
. -o •.•.•••.•?:vp.v.:-;.'
k ixl
;; Bathroom
i
J
gC=3
R
-*-H
To pressure :/>v'..;«..;:•; -.o.-.;. -. : ?. •. .
3' • * • ••' •• • '• P-' ••'•?• *
'•.'-''l?y::'/•'•'<>•:
— Pump-grinder unit
FIGURE 7-16. TYPICAL PUMP-GRINDER INSTALLATION
-------
7-23
sized to handle any number of connections. Another advantage, in a remote
community, is that, with the pump-grinder unit in each building, the O&M
costs for the majority of the sewage collection system will be paid by
the building owners as they pay for the electricity and maintenance of
their pump. This essentially eliminates billing and collection of
operational costs from users and if a unit fails because of lack of O&M,
only one user suffers.
The collection lines must be sized to maintain a minimum of one
metre per second scour velocity. The minimum size collection line is
1-1/4 inch, which would be the size for one unit. If more houses are
added than were originally planned for, velocities will increase down the
line. The effect of this velocity increase is an increase in head loss
which, within reason, is not a problem because the individual pump-
grinder units have a very flat pumping rate vs head curve. Pressures
should be held below 275 kPa (40 psi) in the layout, and the lines should
be slightly undersized (higher velocity) rather than oversized if the
correct size (for one metre per second) is not available. In the design
of a pressure system, an assumption that 33 percent of the pumps will be
operating at once is recommended for sizing pipes. The collection lines
should be constructed to drain to low points if the system has to be shut
down during the winter. In low flow conditions where heat losses may be
extreme (such as at night in the winter in an above-ground situation) or
where the minimum scouring velocity (one metre/second) cannot be met, the
pressure collection lines should be looped back to a water source so warm
water can occasionally be pumped through the lines. Air relief valves
should be installed at major high points in the line.
The pump-grinder units can be situated in each building or
several buildings could drain into one unit by gravity (like the system
in Bethel, Alaska [2]). The units should be designed to pump against the
design head in the main plus a 40 percent overload (with 33 percent of
them operating at once). Each unit should have complete duplication of
controls, sump pumps, and pumps or compressor, for standby. The extra
unit would take over if the primary unit is inoperable and, at the same
time, set off a warning device (audible and visual) to alert the operator
-------
7-24
that repairs are required. Standby power should be available in case of
a power outage for units serving several buildings. The pumping units
should be well insulated and installed on a stable foundation if they are
placed outside or in the ground. As with manholes they must be protected
from frost jacking forces. Double check valves should be provided on
inlet and outlet to prevent backflow. This is especially important for
pneumatic type pump stations, discussed later. Also, weighted check
valves have proven more satisfactory than spring loaded valves.
The pump-grinder units designed to serve individual buildings
are equipped with positive displacement pumps which have a nearly
constant pumping rate over a wide range of heads (Figure 7-17). The
grinder unit reduces all foreign objects to 6.5 mm size before they go
into the pump. The unit must be able to handle items flushed down the
toilets such as rook, wash rags, utensils, etc. Positive displacement
pumps also require a lower power input to purge the system of air pockets
which could form. The units must be small and light enough that they ean
be easily removed from the sump and repaired while the standby unit
continues to operate.
Grinder pump
typical performance characteristics
400
1000 Inlet
Cover
§
CD 5
3 S
2 g.
15 °
II
0
J I
0 40 80 120 160 200
Number of
grinder pumps connected
Motor breather check valve
32 0 Discharge pipe
Check valve and
• anti siphon valve
"0 2 4 6 8 10 12
Discharge (L/ s), Input power (W < 10
and Input current (amps at 240 VAC)
FIGURE 7-17.
PUMP-GRINDER CHARACTERISTICS (adapted from
Environment/One Corp. Ltd.)
-------
7-25
With a 750-watt (1 hp) pump-grinder unit and a water use rate of
190 L per person/day (50 gpcd), the pump would operate only about three
times per person per day with each operating period lasting about one
minute. Thus, a five-person family would use about 0.5 kWh a day. At
25fc/kWh, this would only amount to about $3.75 per month per family for
electricity.
The sump or tank from which the pump draws must be designed so
that it is cleaned by scouring as the pump operates. The outlet check
valves should be located in a horizontal run to prevent solids from
settling out in them when the pump isn't running. Pressure sensors
should be used to control pumps and alarms because rags and grease tend
to foul float switches. The sump should be sized (450 to 570 litres) to
provide several houses with storage in case of a temporary power outage
or other problem. It is recommended that they be constructed of
fiberglass or plastic for protection from corrosion.
Low water use fixtures should be used with pressure systems
whenever possible (see Figure 7-5).
The pump-grinder units and any compressors, pumps, etc. in
larger lift stations should be supplied with low voltage protection and a
relay that will stop the motors in case of a major voltage fluctuation.
This device would also protect the motor under a locked rotor condition.
The pressure system can also be modified by using conventional
submersible sewage pumps in holding tanks at each building. The tanks
are similar to septic tanks where the solids settle, biodegrade
anaerobically, and are pumped out by truck occasionally. The submersible
pump pumps the relatively clear effluent into the pressure sewer lines to
a treatment facility. Some of the advantages of this type of operation
are:
a) Problems with the grinder on the pump plugging up are
eliminated.
b) There are no solids to settle in the collection lines.
c) The treatment facility Is not as complicated as for
conventional sewage.
-------
7-26
7.4.4 Vacuum sewage collection systems
As with pressure systems, a vacuum sewage collection system is
sensible only if soil conditions and community layout make a gravity
collection system not feasible. The vacuum sewer system is detailed in
Figure 7-18. Toilet wastes, with a small amount of water, are trans-
ported in the pipes by the differential pressure between the atmosphere
(air admitted to the system with the flushing action) and a partial
vacuum in the pipe created by a central vacuum pump. The flow conditions
are slug-type, but the friction in the pipe breaks down the water slug.
To reform the slug flow, transport pockets are required at intervals of
about 70 to 100 m [3,5]. Vacuum systems are not limited to holding grades,
but are limited to 4.5 to 6 metres in elevation differences because they
are operated at 56 to 70 kPa (8 to 10 psi) vacuum. The vacuum toilets
(Figure 7-19) only require 1.2 litres of water to flush and the collection
lines are small (2"). The requirement for transport pockets (traps) is a
disadvantage of the vacuum system. The traps will have liquid standing
in them for extended periods of time so they must be inside a heated
utilidor or be well insulated. They should also be provided with drains.
Vacuum systems are limited to 30 to 50 services on a given collection line.
Leakage out of the sewage collection lines is essentially
eliminated, and there is little possibility of sewage contaminating a
water line in a utilidor. The need for house vents and P-traps, with the
freezing problems that accompany them, is also eliminated.
Vacuum systems can also be used to collect sewage in large
apartment buildings.
The vacuum system was developed in Sweden. Manufacturers and/or
distributors [6,7] in the U.S. and Canada should be contacted to obtain
the latest design standards as improvements are being incorporated
continuously.
The collection line sizes will depend on the number of fixtures
on a line and the estimated number which will be operating simultaneously.
Usually 2 to 2-1/2 inch lines are used with the traps dipping at least
one and one-half pipe diameters. Tests have shown that head losses
increase about 3.37 kPa (one inch of mercury) for each 300 m of collec-
tion line velocities of 4.5 m/s or less. Because the lines carry a
-------
7-27
Vacuum pump
v. Air —
Vent
Bath
Grey water valve
Service liquid tank
Transport pocket
\\
t; One-pipe vacuum main
Vacuum collection tank
. ) Pressure pump
Vent
Sink
Vacuum toilet
Vacuum toilet
To treatment and disposal
\_
Grey water valve
FIGURE 7-18. ONE-PIPE VACUUM SYSTEM SCHEMATIC
Vacuum toilet
Flushing mechanism
Vacuum main
Discharge valve
FIGURE 7-19. VACUUM TOILET
-------
7-28
combination of air and water, head losses are nearly impossible to
compute. However, when going uphill, the increase in head loss is only
about 20 percent of the actual elevation increase. Most fixtures will
not flush if there is less than 41 to 48 kPa (6 to 7 psi) vacuum in the
collection lines. Thus, if several are flushing simultaneously and the
vacuum drops to 41 to 48 kPa, additional fixtures will not flush until
the vacuum builds back up. Grey water (sink, shower and tub wastes) can
be separated from black water (toilet wastes) for treatment purposes or
water reuse, by having the toilets on a different collection line than
the grey water fixtures. In low use lines where it is not desirable to
have sewage stand in the traps for extended periods, an automatic or
timed valve can be installed to bleed air into the end of the line and
keep the wastewater moving. Full opening ball valves should be installed
approximately every 60 m so that sections of the lines can be isolated to
check for leaks or plugs.
A collection tank is located at the end of the collection lines.
The tank is held under a vacuum at all times by liquid-ring vacuum pumps
which must be sized to evacuate the air and liquid admitted to the system
by the users with a safety factor of two. In Noorvik, Alaska, the design
figures used were six flushes per person per day for the toilets and 115
litres per person per day for sinks and showers [3], For 50 houses,
pumps were selected which were capable of evacuating 1.8 m / minute
at a vacuum of 53 kPa (16" of mercury). The collected wastes are then
pumped out of the tank to the treatment facility using conventional
centrifugal pumps. They must be designed to pump with a negative suction
head equal to the maximum vacuum under which the tank must operate. The
collection tank is sized similar to the pressure tank in a hydro-pneumati
system. One-half of the tank capacity is used for liquid storage and thee
other half is space (vacuum) serving as a buffer for the vacuum pumps.
Several alarms should be included in the tank to give warning of high
levels of sewage in the holding tanks, low incoming sewage temperature,
and low vacuum in the system.
The plumbing fixtures in the building are the third important
part of a vacuum system. Grey water valves (Figure 7-20) collect water
from the showers, tubs, sinks, and lavatories. These individual fixtures
-------
7-29
Atmospheric air
Vacuum
Pneumatic connection
Sensor-timer
Atmospheric air
3-Way valve
Rubber sleeve
Vacuum chamber
Check valve
Outlet (vacuum)
FIGURE 7-20. GREY WATER VALVE
are conventional but the addition of water use restricting devices is
recommended. The grey water valve is activated by pressure from water
upstream in the fixture drain line through a small pressure-operated
diaphragm. This diaphragm is mounted in a tee just upstream from the
valve. As grey water drains from the fixture, it hits the closed valve
and backs up against the diaphragm, activating it and allowing the vacuum
in the collection main line to open the valve. The length of time the
valve is open is controlled by a timer. The cycle will continue until no
more grey water flows into the line and the fixture is empty. The grey
water valves allow equal parts of air and liquid to enter the system
(e.g., 115 litres of waste and 115 litres of air per person per day in
Noorvik).
Vacuum toilets resemble conventional flush valve toilets (see
Figure 7-19). They are activated by push buttons which expose the waste
in the bowl to the vacuum in the main. The button activates the
discharge valve and a water valve at the same time. The water valve
allows about 1.2 litres of water from the water system to enter the
toilet bowl for cleaning purposes. The discharge valve closes shortly
before the water valve, allowing a small quantity of water to remain in
-------
7-30
the toilet. The toilet discharge valve allows 100 parts of air per one
part of liquid into the system or 120 litres of air per flush. The
fixtures have been relatively trouble free at Noorvik, Alaska, for the
three years that system has been in operation [3].
7.4.5 Other collection systems
Other collection systems have been investigated, such as the
possibility of using oil or antifreeze solutions to transport the sewage.
However, none of them have proven feasible for a community or camp
collection system.
7.4.6 Piped collection system materials
(See Appendix A).
7.4.7 Pressure and alignment testing of sewer lines
Pressure sewer lines should be tested as any pressure water line
would be. If using water or liquid, use 1-1/2 times the working
pressures with an allowable loss of 10 litres in 24 hours. If using air,
use 1-1/2 times the working pressure with an allowable loss of 103 kPa
in 24 hours. Great care must be exercised when using compressed air
because of the possibility of explosion. Air testing must be used at
below freezing temperatures.
Standard tests are satisfactory for air testing gravity sewer
lines. An exfiltration test for water-tightness should be used where
gravity sewer lines are above the watertable. The test should be made
between manholes by blocking the lower manhole to a depth one metre over
the top of the valve. The leakage should be measured by checking the
drop over a period of two hours minimum. The maximum allowable
infiltration or exfiltration, including manholes, should not exceed 190
litres per 24 hours per 300 metres of sewer per 25 mm of pipe diameter
for each isolated section tested.
The alignment and grade of the completed sewer main or one under
construction can best be checked by lamping the line. This operation is
performed by simply shining a light through the line from a manhole and
observing the alignment. Horizontal and vertical curves in sewer mains
are not recommended but are permitted under most codes.
-------
7-31
7.5 Lift Stations
Sewage lift stations are used mainly with gravity collection
systems but could be used with pressure sewage collection systems, and
even vacuum systems (to pump the waste from the collection tank to the
treatment facility).
7.5.1 Types
Table 7-2 presents the advantages and disadvantages of each type
of lift station.
7.5.2 Cold regions adaptations
The following modifications should be made to conventional lift
stations in cold regions.
The outside of the station should be insulated with at least 8
cm of urethane or styrofoam with an outer protective covering to protect
the insulation from moisture. Insulation should be placed underneath the
station to prevent settling due to the thaw of frozen ground. Visqueen
(plastic) or some other bond breaker should always be used to reduce
frost jacking in the active layer. If thawing and settling under the
station is anticipated, pile foundations extending well into the perma-
frost are recommended. All stations must be attached to concrete slabs
to provide sufficient weight to overcome the buoyancy of the station
itself if it were completely submerged in water. Pressure coupling
(flexible) type connections are recommended at the inlet and outlet of
the stations to prevent differential movement from breaking the lines.
A lift station should never be installed in the ground without
immediately placing the heater and dehumidifier into operation.
Condensation from cold surrounding ground could corrode the controls and
electrical connections.
Alarms are an absolute necessity in any lift station. All
critical components, such as pumps and compressors, should be duplicated
in each station. The controls should allow the operator to specify
operation of a pump or compressor, with the identical standby unit taking
over if one or the other does not start. An alarm (both visual from the
surface and audible) would then warn the operator that one unit is
malfunctioning. The alarms can also be set for the temperature and water
level in the station (to warn of a sump pump malfunction). These alarms
-------
7-32
TYPE
TABLE 7-2. TYPES OF LIFT STATIONS
ADVANTAGES
DISADVANTAGES
1. Submersible
2. Dry Well
3. Wet Well
4. Suction Lift
5. Pneumatic
Ejector
Low initial cost; low
maintenance requirements;
does not require installa-
tion of appurtenances
such as heaters, dehumidi-
fiers, sump pump, etc.;
station can easily be
expanded and increased in
capacity; available for
wide range of capacities.
Little of the structure
is above ground so
heat losses are greatly
reduced.
Pumping equipment located
away from wet well; low
cost per gallon capacity;
good reliability; high
efficiency; desirable
for large installations;
easily maintained.
Low initial cost; high
efficiency; wide range
of capacity available
Good reliability; avail-
able for wide range of
capacity.
For low capacity (40 gpm
or 150 L/minute) low
head, for short distances;
generally nonclogging,
380 L/minute (100 gpm)
maximum usually.
Difficult to make field
repair of pump, requires
specialized lifting
equipment to remove
pump.
High initial costs;
requires larger
construction site.
Requires explosion proof
electrical motors and
connections; difficult
to maintain pump.
Suction lift limited to
4.5 metres; decrease in
priming efficiency as
pump ages.
Somewhat more complex
than other types of
stations; high mainten-
ances; low efficiency.
-------
7-33
should be tied back into a central alarm panel in the puraphouse or
operator's house, and can be connected to the operator's and/or the fire
or police department's phone. Standby electrical power should be
provided for each major lift station.
Inlet screens must be provided to remove items that would clog
pumps or check valves. Each lift station should be checked by the
operator and the inlet screen cleaned daily. Submersible types or those
without a heated dry well in which to work should be housed in a heated
surface structure with the electrical controls and alarms. All entrance
manholes must extend above the ground surface sufficiently to be above
any flooding or snow drifts. Also, manhole entrances or building
entrances must be kept locked. All pumps or motors should be supplied
with running time meters for measuring flow rates; conventional water
meters do not work properly with sewage. Corrosion protection should be
provided for the metal shell in each station. Sacrificial and corrosion
protection systems do not work well when the ground surrounding the anode
or lift station is frozen.
7.5.3 Force mains
Force mains are pressure lines into which the pumps in the lift
station discharge. They should be designed to have scour velocities
during pumping (2—1/2 to 3 ft/sec or 7.5 to 9 m/s) and to drain between
pumping cycles. If this is not possible the line must be placed in a
heated utilidor or heat traced in some way. Another option would be to
time the pumping cycle so the sewage stays in the line for a calculated
period, and to size the holding tank at the lift station to hold at least
the volume of the force main. The mains should be pressure tested and
they should meet all the criteria of pressure water transmission
pipelines (see Section 3). If they empty into a manhole, the entrance
should be at least 0.7 m above the exit line.
7.6 Building plumbing
Service lines and their connections to the buildings were
discussed earlier. The special plumbing needed with vacuum sewers was
covered in the section dealing with vacuum collection systems.
-------
7-34
The use of floor-mounted, rear-flushing toilets keeps all waste
plumbing lines in the walls of the building and out of the floors (10 cm
above the floors). These toilets are readily available. Wall-mounted,
rear-flushing units are not recommended unless the wall is reinforced
because the wall supports the entire weight of the toilet and the user.
The floor-mounted, rear-flushing units must be carefully installed; over
-torquing the flange bolts will crack the base. Examples of floor-
mounted, rear-flushing toilets are the "Yorkville" by American Standard
or the "Orlando" by Eljer. Tubs should be placed upon blocks so the
entire trap and drain is 10 cm above the floor. This allows the tub to
drain into the toilet discharge line in the wall. All fixtures should be
placed on inside walls which are warm on both sides. If possible, the
sink should be placed on the opposite side of the bathroom plumbing wall
to reduce the length of drain lines. All fixtures and lines should be
installed so that they can be drained or otherwise protected from
freezing. Drainable p-traps should be used and the user should be aware
that antifreeze solution should be added to his toilet if there is a
danger of freezing. Stop and waste valves should be provided at all low
points in house water supply lines. Home owners must be trained to
maintain the facilities after they are installed. They need to know how
to order parts, how to repair leaky faucets and toilets, and what not to
flush down toilets.
House vents frequently frost over in cold weather. They should
be constructed of low conductivity material and should increase in size
as they go into the unheated attic. One and one-half inch vents should
be increased to 3" and 3" to 4" and insulated in extreme circumstances.
7.7 Typical Construction Costs
Table 7-3 gives estimates of 1977 unit construction costs.
7.8 References
1. Gamble, D.J. and Janssen, C.T.L., "Evaluating Alternative Levels of
Water and Sanitation Service for Communities in the Northwest
Territories", Canadian Journal of Civil Engineering, Vol. 1, No. 1,
1974.
-------
7-35
Item
TABLE 7-3. UNIT CONSTRUCTION COSTS (1977)
Cost in Place* Remarks
Buried Utilidors
On-surface
Above-surface
Buried
Pipeline
Rock excavation
Permafrost
excavation
Normal Excavation
On-surface
Pipeline
Above-surface
Pipeline
Sewage grinder
pump and sump
Manholes
Lift stations
Tracked hauling
vehicle (2250 1)
Truck hauling
vehicle (4500 1)
Vacuum toilet
fixtures
(plumbing)
$400 to $l,200/m
$200 to $300/m
$600 to $l,700/m
$90 to $300/m
3
$50 to $75/m
3
$40 to $80/m
3
$20 to $30/m
$60 to $100/m
$120 to $300/m
$3,200
$1,500 to $2,000
$18,000
$45,000
$25,000
$2,600
Does not include excavation.
Depends on how many lines
are included.
Depends on backfill material.
Depends on lines included
Costs depend on foundation
(piling, etc.).
Depend on lines included.
Does not include excavation
Depends on Backfill material.
Depends on water content and
time of year excavated.
Depends on foundation
(piling, etc.).
Two pumps in sump.
Does not include excavation
Depends on size, does not
include excavation
With tank, etc.
With tank, etc.
In existing house.
-------
7-36
Table 7-3. (CONT'D)
Item
Cost in Place
Remarks
Refuse packer
unit on 1-1/2
ton truck
Low water use
toilet
Plumbing a
house
Waste disposal
bunker (cribs)
House holding
tanks
$30 000
$2200
$2100
$800
$3500
In existing house.
Toilet, sink and lavatory.
Includes fixtures.
Includes excavation.
5' deep x 6' x 6'
Water and waste
* All costs vary with transportation (see Section 2). Those costs given
are representative for mid-arctic conditions.
-------
7-37
2. Ryan, W.L. and Rogness, D.R., "Pressure Sewage Collection Systems in
the Arctic", Proceedings of Symposium on Utilities Delivery in
Arctic Regions, Report no. EPS 3-WP-77-1, Environmental Protection
Service, Environment Canada, Ottawa, 1977.
3. Rogness, D.R. and Ryan, W.L., "Vacuum Sewage Collection in the
Arctic: Norvik, Alaska - A Case Study", Proceedings of Symposium on
Utilities Delivery in Arctic Regions, Report no. EPS 3-WP-77-1
Environmental Protection Service, Environment Canada, Ottawa, 1977.
4. Cadorio, P.M. and Heinke, G.W., "Draft Manual for Trucking
Operations for Municipal Services in Communities of the N.W.T.",
Publication of Dept. of Civil Eng., Univ. of Toronto, Oct. 1972.
5. Averill, D.W. and Heinke, G.W., "Vacuum Sewer System", Indian and
Northern Affairs Pub. No. QS-1546-000-EE-A, Information Canada,
Sept. 1974. Also available from Dept. of Civil Engineering,
University of Toronto.
6. Colt Industries, Beloit, Wisconsin 53511, U.S.A.
7. Vacusan Systems Ltd., #12, 6115-4th St., S.E., Calgary, Alberta, T2H
2H9.
7.9 Bibliography
Alter, A.J., "Sewerage and Sewage Disposal in Cold Regions", U.S.
Army Cold Regions Research and Engineering Laboratory M3-C56,
October 1969. 106 p., AD-698452.
Environment Canada. Environmental Protection Service, Proceedings
of Symposium on Utilities Delivery in Arctic Regions, Report No.
EPS 3-WP-77-1, Environmental Protection Serivce, Environment Canada,
1977.
Gamble, D.J. and Janssen, C.T.L., "Estimating the Cost of Garbage
Collection for Settlements in Northern Regions", Northern Engineer,
Winter 1974-75.
Gamble, D.J., "Wabasca-Desmarais Water and Sanitation Feasibility
Study", prepared for the Northern Development Group, Alberta
Executive Council, 1974.
-------
SECTION 8
UTILIDORS
Index
8 UTILIDORS 8-1
8.1 Introduction 8-1
8.2 Design Considerations 8-4
8.2.1 Utilidors with central heating lines 8-5
8.2.2 Utilidors with pipe heat tracing 8-7
8.2.3 Above-ground Utilidors 8-7
8.2.4 Below-ground Utilidors 8-9
8.3 Components and Materials 8-11
8.3.1 Foundation 8-11
8.3.2 Frame 8-12
8.3.3 Exterior casing 8-13
8.3.4 Insulation 8-13
8.3.5 Piping 8-14
8.3.6 Cross-section design 8-14
8.3.7 Prefabricated Utilidors 8-15
8.4 Appurtenances 8-15
8.4.1 Above-ground hydrants 8-15
8.4.2 Sewer Access 8-16
8.4.3 Vaults 8-17
8.4.4 Utilidor crossings 8-17
8.5 Thermal Considerations 8-18
8.6 Maintenance 8-20
8.7 Costs 8-20
8.8 References 8-21
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List of Figures
Figure Page
8-1 Various Utilidors Installed in Cold Regions 8-2
8-2 Temperature Variation in a Utilidor with Central Hot
Water Distribution, Fairbanks, Alaska 8-7
8-3 Road Crossings for a Utilidor with Central Heating
Lines, Inuvik, NWT 8-8
8-4 Buried Utilidor under Construction, Nome, Alaska 8-10
8-5 Above-ground Utilidor Hydrant 8-16
8-6 Sewer Cleanouts 8-17
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8-1
8 UTILIDORS
8.1 Introduction
Utilidors are conduits that enclose utility piping which,
in addition to water and sewer pipes, may include central heating, fuel
oil, natural gas, electrical and telephone conduits. Utilidors may be
located above, below, or at ground level and have been used in stable
and unstable seasonal frost and permafrost soils as well as in snow [1].
They may be large enough to provide access for maintenance purposes or
for use as a walkway, or they may be compact with no air spaces. Single
pipes or separate pipes on a common pile are not Utilidors. The size,
shape, and materials used depend upon the number and types of pipes,
local conditions and requirements, and economics.
Utilidors have been constructed in many northern locations [1].
Perhaps the best-known examples of above-ground Utilidors are in Inuvik,
NWT [2,11,12]. Utilidors have also been extensively used below-ground
in high density areas and in permafrost areas in Russia [8,13].
Examples of various Utilidors that have been constructed in cold regions
are illustrated in Figure 8-1.
Utilidors are not water distribution or sewage collection
systems in themselves. They are commonly used in cold regions to
consolidate piping, and perhaps other utilities, particularly where
central heating pipes are used and for above-ground systems. Also of
significance are physical protection of pipes and insulation, and
thermal considerations. As with other cold regions piping, they must
be insulated to reduce heat loss but often the insulation is located on
the utilidor exterior casing rather than on the individual pipes. Other
freeze-protection measures, such as recirculation to maintain a flow in
water pipes, may also be necessary. Most utilidors have some mutually
beneficial heat transfer between the enclosed pipes. If central heating
pipes are included, heat loss from these can be sufficient to replace
utilidor heat losses and prevent freezing, but with this arrangement
temperature control within the utilidor is difficult. This can lead to
inefficiency and undesirably high temperatures in water pipes. Freeze-
protection alone is not sufficient justification for the use of
-------
3-2
^.
oof panel
75 mm Fiberglass insulation
Insulated high temperature water
supply and return, 200 0 to 32 0
Removable panel 0 759 mm
(22 Gauge) aluminum sheeting
- - Steel support frame
1500 or 2000
Asbestos cement watermain
200 0 Asbestos cement sewermain
U Bolt
Drift pin
Timber pile cap
2500 Timber pile
45m into permafrost
Flexible sealant at overlap points
150 0 Asbestos cement watermain
19 mm Galvanized banding at pipe saddles
•Fiberglass or polyurethane insulation
1 897 mm (14 Gauge)
Corrugated metal pipe
Flexible sealant
2000 or 150 0
Asbestos cement sewermain
Wood pipe saddle
2000 Timber pile
(c) CMP Utilidor, Inuvik, N WT [2]
(a) Utilidor with central heating lines, Inuvik, N WT [2]
610
;Wood frame
150 0 Asbestos cement sewermain
Wood tie down clamp
38 mm Polystyrene insulation
" boards sides and top (glued)
2000 or 1500
Asbestos cement watermain
Loose polystyrene insulation
-4 jl—20 mm Plywood
25 0 Drain hole with screen
Wood pipe support
150 x 150 mm Fir pile cap
75x200 mm Fir beam
Drift pin
200 0 Timber pile at 4 6 m spacing
-1 519 mm (16 Gauge) Steel
,— 2 657 mm (12 Gauge) Steel top
T \J ] \,— 100 mm Polyurethane
300 mm
65 0 PVS Vacuum sewer
25 0 Copper heat trace pipe
-"750'PVC Water
- Wood beam and supports as required
(d) Utilidor with vacuum sewer, Noorvik, Alaska [3]
(b) Plywood box utilidor, Inuvik, N.W.T. [2]
T
430
•430-
100 mm Polyurethane
100 0 Sewer force main
13 mm Plywood
25 0 Copper heat trace
(e) Single pipe with heat tracing, Noorvik, Alaska
FIGURE 8-1. VARIOUS UTILIDORS INSTALLED IN COLD REGIONS
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8-3
Polyurethane insulation
1500 Carrier pipe
38 0 Potable water
38 0 Gray water
38 0 Pipe heat trace-supply
38 0 Pipe heat trace-return
38 0 Treated effluent
300 0 Corrugated metal pipe casing
(f) Utilidor with many small pipes,
Wamwnght, Alaska [4]
Sand pad
Clay trough
Non-heaving soil
(i) Buried accessible utilidor, Mirryl, U.S.S.R [8]
300 mm Corrugated metal pipe
Polyurethane insulation
Electric heating cable
18 mm Copper service lines
40 mm Plastic isolation pipe
100 mm Carrier pipe
Active layer
1 2 to 1 5 m
Ice-rich
permafrost
300mm
Granular base
(minimum)
Granular backfill
Filter fabric
[• Vanes'(6 6 to 1 2 m)
';_L
50 mm Extruded polystyrene board insulation (1 2 m x 1 8 m)
Adjustable chain pipe hanger
200 0 Wood stave sewer pipe
1 7 m Corrugated aluminum plate, 2 54 mm wall
1000, 150 0 or 200 0 Steel, cement lined circulated watermain
when depth of cover less than 09m
Extruded polystyrene board insulation (1 2m X 1.8m)
(g) Service connection [5]
(j) Buried accessible utilidor, Nome, Alaska [9]
445
178
Fiberglass-reinforced
plastic filament wound pipes
Insulation surface treated
~ with mastic or paint
- Electric heating cable (optional)
500 to 2500
" Polyurethane foam insulation
Fiberglass-reinforced
"plastic exterior casing
- Water recirculation pipe (optional)
- Galvanized bolt
Aluminum or galvanized
steel channel
(h) Prefabricated utilidor [6,7]
34m
1 5m
(k) Walkway utilidor, Cape Lisburne, Alaska [1]
FIGURE 8-1. (CONTINUED)
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8-4
utilidors since individually insulated pipes could be used. Utilidors,
or utility tunnels designed for public passage are very expensive, and
are generally not justified for piping alone. However, where they are
required for passage or transportation, there can be overall economic
benefits by locating utility conduits within them.
In North America, utilidors are most commonly constructed
above-ground in permafrost areas. Although below-ground utilities are
preferred, above-ground construction may be necessary where there is
ice-rich permafrost, expensive excavation, or a lack of equipment for the
installation and maintenance of underground utilities. Temporary pipes
or piping that requires access may also be located above-ground.
Utilidors have disadvantages. Their applicability for a
particular location should be carefully assessed before implementation.
Individually insulated pipes, in a common trench or supported by a
common pile (see Figure 6-18) may be a more appropriate and economical
alternative [10].
8.2 Design Considerations
Inclusion of conduits such as electrical power, natural gas,
and telephone cables, along with water and sewer lines in utilidors can
be cost-effective and aesthetic. This practice is generally recommended
wherever practical. The addition of central heating lines may require
significant changes in utilidor design and operation. The use of central
heat generation and distribution is a more complex economic decision.
Walkways are sometimes constructed between buildings in construction
camps or military facilities or in high traffic and severe snow drifting
conditions. In these situations placing utility lines within them should
be considered. In some cases surface utilidors have been designed for
use as sidewalks.
These common functions of utilidors are often the primary
benefit and reason for their use. Some of the problems encountered when
other utilities besides water and sewer pipes are included in the
utilidor are:
a) jurisdiction problems in installation and maintenance;
-------
8-5
b) coordination between various utility agencies during
planning and construction;
c) differences in routing or other conflicting design criteria
for various utilities or utilidor uses;
d) difficulty or restrictions in expansion or changes to
utilities;
e) piping and utilidor design problems, particularly at
intersections and bends;
f) compatibility of materials; and
g) larger size, and perhaps special materials, which increase
the costs of utilidor construction and above-ground road
crossings.
In some situations, such as at industrial camps, military bases or in
planned communities, these problems may be overcome with overall cost
savings and aesthetic benefits.
8.2.1 Utilidors with central heating lines
The decision to use utilidors to carry central heating lines is
secondary to the benefits of central heating. These benefits include
the elimination of less efficient individual building furnaces and a
significant cause of fires, central fuel storage, and the possible use
of waste heat (see Section 14). These pipes often require access,
particularly for steam and condensate return lines. If they are buried,
utilidors are necessary for access. Separate pipes can be used for
above-ground systems and may be more economical, but consolidating piping
within a utilidor may be more aesthetic.
When only central heating lines are considered, utilidors or
individually insulated pipes can be used (see Figures 14-8, 14-9 and
14-11). When central heating and water and sewer lines are installed in
a utilidor, the former can give off enough heat to prevent freezing
temperatures within the utilidor. This may eliminate or reduce the need
to loop and recirculate the water mains, although circulation is always
desirable in cold regions. Because the utilidor exterior is insulated,
conventional, uninsulated water and sewer piping and appurtenances are
usually used. For economical operation the central heating lines are
-------
8-6
usually insulated. In some cases it may be necessary to remove some
insulation from around the heating pipes to provide enough heat during
the coldest ambient temperatures. The utilidor in Figure 8-1(a)
commonly has 0.25 m of insulation removed every 10 m.
Problems occur because the heat source is constant and must
operate for all or most of the year. Therefore, when the ambient
temperature is warmer, the interior temperature of the utilidor will
increase and undesirably high water temperatures can occur when there is
little or no flow in the water pipes (see example 15-5). Users have
found it necessary to bleed considerable volumes of water to obtain cool
water [11]. For this reason it is desirable to insulate the water pipes
[10].
The heating of a large air space in the utilidor is less
efficient than the direct heating of water and its recirculation to
prevent freezing. This inefficiency is more significant for
above-ground and large utilidors. In some situations it will be more
efficient to design and operate the heating and the water and sewer
systems independently. If a utilidor is used the benefits will be
aesthetic for above-ground utilities, accessibility for below-ground
utilities, and structural support for the pipes.
Thermal stratification can cause freezing of lower pipes in
large open utilidors when the average temperature is adequate. Vertical
air flow barriers may be necessary to prevent air currents along
inclined utilidors [11]. Thermal shielding of pipes and poor
temperature distribution within a utilidor are shown in Figure 8-2 [14].
Utilidors for central heat distribution pipes and other
utilities are expensive. Their large size increases the material and
construction costs, particularly for above-ground systems and
road-crossings. Central heating is only economical in relatively high
density developments, not single-family housing areas. With adequate
planning these utilidors can form the backbone of large community
systems, with non-heated utilidors servicing adjacent lower density areas,
Central heating systems must provide continuity of service and
they should be looped so that areas can be isolated for maintenance or
-------
8-7
610-
50 mm Rigid insulation
0.813 mm Aluminum cover
20 mm Plywood
350
50 x 250 mm Wood beam
20 mm Hot water return
20 mm Hot water supply
Approximate isotherm
20 mm Cold water
Thermocouples
Ambient air temperature: -29°C
Hot water input temperature: 69°C
150 mm Steel channel
100 mm Pipe pile
FIGURE 8-2. TEMPERATURE VARIATION IN A UTILIDOR WITH CENTRAL
HOT WATER DISTRIBUTION, FAIRBANKS, ALASKA [14]
repairs, long-range planning is necessary to incorporate future
expansion and to allow efficient staging without the need for temporary
or unused lines to complete loops.
8.2.2 Utilidors with pipe heat tracing
Utilidors with the pipe heat tracing are designed specifically
to supply the amount of heat necessary to prevent freezing of the pipes
in the utilidor. Low temperature, 80°C to 98°C, glycol solutions or
other non-freezing fluids, and small-diameter bare pipes are commonly used
(see Section 15.4.3). They can be used to heat Utilidors or thaw out
frozen pipes. Many of the inefficiencies and problems with central
heating lines do not apply.
8.2.3 Above-ground utilidors
Below-ground utilities are usually preferred, but local
conditions, operating requirements and economics can make above-ground
utilities and utilidors attractive. Factors to be considered when
choosing between above or below-ground utilities are detailed in
-------
8-8
Section 2. It should be noted that above-ground utilities were often
necessary in the past because the types of insulations in common use
required dry conditions and accessibility. For the same reason, buried
accessible utilidors were used. The development and availability of
near-hydrophobic rigid plastic foam insulations, such as polyurethane and
extruded polystyrene, has made buried systems feasible and more
attractive in many situations.
Above-ground utilidors should be as compact and as close to the
ground as practical to reduce the obstruction to traffic. Low utilidors
also reduce the elevation of buildings necessary for gravity sewer
drainage. Utilidors with central heating lines are often large and
require expensive wood or corrugated metal arch structures at road
crossings (Figure 8-3). Vacuum or pressure sewer systems may be
attractive in undulating areas since the utilidor can follow the ground
surface or can be buried at a constant depth. These systems use smaller-
diameter pipes than gravity systems. When small-diameter water and
sewer pipes are used, the utilidor size can be reduced (see Figure 7-8).
(a) Wood
(b) Corrugated Metal Arch
FIGURE 8-3. ROAD CROSSINGS FOR A UTILIDOR WITH CENTRAL HEATING LINES
INUVIK, NWT
-------
8-9
Above-ground util^'dors are located within rights-of-way behind
building lots where both physical and legal access are provided.
Buildings should be located near the utilidor to reduce the length of
service lines. A minimum of 3 m between building and utilidor is often
specified for fire protection. The street layout must consider the
looping of water mains for recirculation, the expense of road-crossings
and vaults, and the high cost per metre, which are characteristics of
above-ground utilidors. An example of good planning is illustrated in
Figure 2-14.
Utilidors have been routed through the crawl space in buildings
to provide thermal and physical protection for the pipes, eliminate the
service connection utilidettes which are the most freeze-susceptible
portion of cold regions utility systems, and reduce the length of
utilidor and right-of-way required. Problems with this layout can
include the provision for access to piping and the danger of fires which
could jeopardize the community utility system. Fire and smoke can
travel along utilidors to other buildings. Fire resistant materials and
fire cutoff walls have been used to minimize this danger.
People often walk on utilidors, but because the travelled
surface and utilidor will require increased maintenance this is often
discouraged by design and legislation. In some locations, they have
been designed as sidewalks, but this is often impractical because of the
routing requirements for the utilidors and their elevation.
8.2.4 Below-ground utilidors
Although buried utilidors, usually of concrete, have been
constructed in unstable soils in many large communities in northern
Russia, they have had limited application in the cold regions of North
America and in Antarctica [1]. Few buried utilidors have been con-
structed without the inclusion of central heating lines and perhaps other
conduits besides water and sewer pipes. A notable exception to all of
these generalities is the corrugated metal pipe utilidor for water and,
sewer lines in Nome Alaska (Figures 8-1(j) and 8-4). The primary
advantages of buried utilidors are access for maintenance and repairs,
the consolidation of utilities in a single structure and trench, and thermal
-------
8-10
FIGURE 8-4. BURIED UTILIDOR UNDER CONSTRUCTION,
NOME, ALASKA
considerations which may include freeze-protection and ventilation to
reduce the thawing of permafrost. In some cases, individual pipes or
utilidors without an air space (for example Figures 8-1(h) and 14-11)
may be appropriate and more economical.
Below-ground utilidors are subject to ground movements from
frost-heaving or thaw-settlement and groundwater infiltration, and this
has caused failures in ice-rich permafrost. To prevent progressive
thawing of permafrost, open utilidors with natural ventilation have been
used in Russia. Vents are opened during the winter to maintain
sub-freezing temperatures within the utilidor and refreeze the
foundation soils that were thawed the previous summer. Other foundation
designs that can be used in permafrost areas include the provision of
supports, refrigeration, insulation, and improving the foundation soils
within the expected thaw zone (see Section 15.6.1). Groundwater, melt-
water and water from pipe breaks must be considered in both unstable and
stable soils. In the spring, flooding can occur in buried utilidors
-------
8-11
which have an air space. Provisions to allow drainage of the utilidor
must be made; watertight utilidors are desirable and usually required.
Diversions or cutoff walls in the trench may be necessary in permafrost
areas to prevent detrimental groundwater flow along the trench.
8.3 Components and Materials
Utilidors that are well designed and constructed with high
quality materials have a longer useful life, cost less to operate and
provide more reliable service. Utilidors which have performed best were
constructed with metal exterior casing, used closed-cell insulation,
were structurally sound and had a solid foundation [2], The basic
components of a utilidor are:
a)
b)
c)
d)
e)
foundation,
frame ,
exterior casing,
insulation, and
piping.
Foundation
8.3.1
Foundation considerations and design will be different for
utilidors that are below-ground, at ground level or elevated. Each
requires site investigations and designs that will accommodate, reduce
or eliminate the effects of frost-heaving, settlement and surface and
subsurface drainage.
Above-ground utilidors must be supported to provide grades for
gravity sewers and to allow the draining of pipes and the utilidor. Pipes
must be adequately anchored to resist hydraulic and thermal expansion stresses.
Where ground movements are within acceptable limits, utilidors
can be installed directly on the ground, or on a berm, earth mounds,
sleepers or posts.
In unstable areas utilidors are commonly supported on piles
which are adequately embedded into the permafrost (see Section 15.6.3).
The piles are dry augered if possible because thawing the permafrost
with steam or hot water increases the freeze-back period and
frost-heaving. Because of the light vreight of utilidors, the vertical
loads on the piles are relatively small and frost-heaving will usually
-------
8-12
be the most significant design consideration for embedding piles.
Lateral forces may be significant on some permafrost slopes, and lateral
thermal expansion and hydraulic stresses must be considered at bends.
Various types of piles have been used to support above-ground piping.
The selection depends upon the availability of local materials, the
length of pile required and economics. Piles used in Inuvik, NWT, are
usually rough timber poles and are embedded 4 to 6 m. At Norman Wells,
NWT, frost-heaving is severe and 100-mm diameter steel pipe is driven 12
m and grouted to the fractured shale bedrock. Piles may cost from $200
to over $750 each and may account for 10 to 20% of the total cost of
above-ground utilidors. Small utilidors are usually placed on a single
pile, but large utilidors may require double piling for stability. The
utilidor structure must be adequately anchored to the pile foundation.
Pile caps are often used to allow for poor alignment.
Buried utilidors in stable soils have conventional design
considerations which include surface loads. Frost-heave must be
considered for shallow-buried utilidors, and in ice-rich permafrost
soils, thawing must be prevented or considered in the design (see
Section 15.6.1).
8.3.2 Frame
The supporting frame must keep the above-ground utilidors rigid
in spanning piles or other supporting structures. The utilidor dead
loads, live loads including people, and stability must be considered in
the structural design. In some instances steel has been used, but
wooden beams are more common. Solid utilidors may utilize the pipe,
insulation and shell for beam strength (Figure 8-1(g,h)). An economic
analysis would indicate the best spacing of piles versus increasing the
beam strength of the utilidor frame. Utilidors supported by wooden
beams in Inuvik, NWT, usually span 4.5 m. Steel beams or pipe can be
used to span up to 7.5 m, which is generally the practical limit without
special designs.
Buried utilidors must also have some beam strength to hold pipe
grades and span local poor bedding or foundation soils. Beam strength
is usually incorporated into the exterior casing.
-------
8-13
8.3.3 Exterior Casing
The primary function of the exterior casing is usually to hold
the insulation in place and to protect the pipes from the weather and
physical damage. When the exterior casing is an integral part of the
structural strength and rigidity it is usually metal or fibreglass with
polyurethane insulation bonded to it.
The outer shell of above-ground utilidors should be designed
for easy removal to provide access to piping. This is particularly
important at appurtenances, but is desirable along the complete utilidor.
The joints in the sections must be designed to seal against rain, snow
or air infiltration. Drain holes located in the bottom should be prov-
ided periodically to allow drainage in case of a pipe break.
Materials that have been used for the exterior casing include
corrugated and sheet metal, plywood or wooden beams, and fiberglass
reinforced plastic. Concrete has also been used for surface or buried
utilidors. Although wooden box utilidors have the lowest capital cost,
they have a low life expectancy and the highest maintenance costs due to
painting requirements and physical damage. Wood is easy to work with
and the utilidor, vaults and service connections can be easily constr-
ucted on-site even in cold weather. Wooden utilidors are sometimes
covered with a thin metal sheet or asphalt paper. Metal utilidors may
be difficult to fabricate and install, particularly at bends, junctions
and appurtenances. They are rugged and have a longer life expectancy,
and require less maintenance than wooden exterior casing utilidors.
Below-ground utilidors require a rigid exterior casing that
is watertight and provides the structural strength required by the
utilidor.
8.3.4 Insulation
Insulation is probably the most critical component in all cold
regions piping systems, including utilidors. Water can enter the
utilidor at joints or from breaks in the pipes, and it is impractical to
keep the insulation dry. Insulations that absorb moisture lose their
insulating value, particularly when the moisture freezes; therefore,
-------
8-14
asbestos fibre, rock wool, glass fibre, wood, sawdust, peat moss and
similar materials are undesirable and must not be used in inaccessible
utilidors. Polyurethane, and expanded and extruded polystyrene are the
most common insulations used. Ground or bead polystyrene and foamed-in-
place polyurethane can be used to fill the voids in utilidors. The
former provides access to pipes for repair and removal. Fire resistant
insulations are preferred since they reduce the spread of fire along
utilidors.
Thermal characteristics of various insulations are given in
Appendix C and Section 15.7.2.
8.3.5 Piping
Leaks from pipes and joints in utilidors may cause water and
icing damage to the utilidor, and there is also a danger of contamina-
tion and cross-connections. Most public health codes do not allow the
proximity of water and sewer pipes. Wavers or adoption of new codes
will be necessary before utilidors can be used. In the Northwest
Territories, water and sewer pipes are allowed in a common trench or
utilidor if pressure-rated pipes and joints are used and all pipes are
tested for zero leakage. Open sewers are not allowed and sewer
cleanouts must be capped.
Most types of pipe materials have been used in utilidors. Each
has advantages and disadvantages. Rigid pipes with welded or equivalent
joints may not require as much support or hydraulic thrust blocking at
bends, hydrants and intersections, but the design must allow for thermal
expansion.
8.3.6 Cross-section design
The cross-section design and piping arrangement will depend
upon the access required and type, size and number of pipes to be
included in the utilidor. Other considerations may include standard
sizes of materials, for example 4 feet x 8 feet plywood sheets, and the
routing of piping. The utilidor size is often dictated by the maximum
dimensions of pipe appurtenances, repair clamps and joints, and the
spacing of pipes that is necessary at deflections and intersections.
-------
8-15
Pipes with smooth joints may be placed closer together and a smaller
cross-section may be used. Installation, repairs and maintenance
requirements must also be considered.
8.3.7 Prefabricated utilidors
Most utilidors are prefabricated to some extent, but all
require some field construction. The primary advantage of
prefabrication is the reduction in field-erection time. This reduces
labour costs and facilitates installation within the short construction
season, but prefabricated utilidors generally have high material costs.
High quality control and special designs are possible in shop
fabrication. Prefabricated utilidors commonly combine the functions of
the basic utilidor components. The pipes, rigid insulation and exterior
casing provide beam strength, rigidity, and thermal and physical
protection.
One type of prefabricated utilidor consists of a carrier pipe,
polyurethane foam insulation, and a bonded exterior casing of sheet or
corrugated metal, glass fiber reinforced plastic or plastic, depending
on the strength requirements (see Figures 8-l(f)(g), A-l and A-2). This
system is commonly used for small-diameter pipes and service connections
to buildings. A completely prefabricated glass fibre reinforced plastic
two-pipe utilidor system is illustrated in Figure 8-1(h). It is
longitudinally segmented and has staggered joints to allow removal of
individual pipes.
Appurtenances such as hydrants, cleanouts, and bends are
prefabricated modules that are inserted into the system where required
[16].
8.4 Appurtenances
Some appurtenances for piping systems and utilidors must be
specially designed or adapted. This applies particularly for above-ground
utilidors, where special hydrants, valves, cleanouts and bends may be
necessary.
8.4.1 Above-ground hydrants
"In-line" hydrants located directly on a tee in the water main
are recommended. They may be installed without additional freeze prot-
-------
8-16
action if the barrel is short enough that heat from the water main will
prevent the valve from freezing. Leakage through the valve must be
prevented since the freezing of water may damage the hydrant and make
thawing necessary before use. Building-type fire hydrant outlets and
butterfly valves have been used because of their small size and light
weight. One design is illustrated in Figure 8-5.
Flanged tee
Hydrant housing filled
with loose batt insulation
Utilidor
-Butterfly valve with 50x50mm
square operating nut
Watermain
2-Way Siamese connection
Removable end cover
Steel stub flange
FIGURE 8-5. ABOVE-GROUND UTILIDOR HYDRANT
The hydrant enclosure must be rugged, well insulated, and
appropriately marked and painted. Access to the hydrants must be quick
and easy but it must also discourage vandalism.
8.4.2
Sewer access
For above-ground sewers, and water and sewer pipes within a
utilidor, the sewer access cleanouts must be sealed to prevent
cross-contamination. The flanged tees for pipes larger than 200 mm
diameter usually provide an adequate opening to insert cleaning or
thawing equipment. Standard fittings for smaller pipes do not provide
adequate access in both directions. Special fittings with larger slot
openings that can be sealed have been used (Figure 8-6). Special venting
may be necessary when the building vents are not adequate.
-------
8-17
Galvanized bolt
Lid
Flange
H»-200mm-—I
750mm
. Rubber gasket
Flange
Brass nut
Fiberglass reinforced plastic
Cloth impregnated rubber gasket to
indicate when pipe is under pressure
Steel
FIGURE 8-6. SEWER CLEANOUTS
J.4.3
Vaults
Vaults are the above-ground enclosures which contain the
hydrants, valves, thrust blocks, intersections, bends, and other piping
system appurtenances, including recirculation pumps, heaters and
controls. Access to these appurtenances is provided through the vaults,
which can be only slight enlargements of the utilidor, or small
buildings. Usually they are individually designed and fabricated.
Thrust blocking and vaults at bends may not be required where small-
diameter pipes or rigid pipes are used. The vaults contain the
expensive piping system appurtenances which can be a significant portion
of the total utilidor cost. Vaulted appurtenances accounted for 30% of
the cost for the two-pipe wooden box utilidor shown in Figure 8-l(b).
8.4.4 Utilidor crossings
Pedestrian and vehicle crossings must be provided where
above-ground utilidors are used. The cost of these crossings is a
function of the utilidor size and its height above the ground. Large or
high utilidors require bridge-type structures for road overpasses
(Figure 8-3). Costs in 1977 were approximately $35 000 in Inuvik, NWT.
-------
8-18
Smaller utilidors can be protected by less expensive corrugated metal
pipe culverts (see Figure 7-8).
The utilidor and road layout should minimize the number of
crossings that are required. The roadway and drainage system must take
into consideration the locations of utilidor overpasses. Steep
approaches to the crossing can impair driver visibility. Long
approaches can disrupt the surface drainage system, and the overpasses
tend to become drainage paths that accumulate garbage.
Utilidors and piping can also be elevated above roadways or
buried at road crossings. These alternatives may require expensive lift
stations which can impede the complete drainage of the pipes and
utilidor. Underpasses can be excavated, however, this is difficult and
expensive in areas of ice-rich permafrost. In 1974, the roadway
excavation, permafrost protection and utilidor reinforcing for an
underpass in Inuvik, NWT, cost $70 000.
Pedestrian crossings can be a part of the roadway crossings
but separate wooden stairways may also be required at certain locations.
8.5 Thermal Considerations
The placement of pipes within a utilidor provides possible
thermal benefits in that the proximity of water mains to warm sewer
pipes, and heating pipes if they are included, reduces the risk of
freezing and partially compensates for heat loss. It is important to
minimize the surface area of the utilidor to reduce heat loss. The size
and shape of a utilidor may, however, be dictated by considerations
other than heat loss. Most utilidors are no more thermally efficient
than individual pipes with annular insulation, and utilidors containing
large air spaces will be less efficient. The effects of utilidor shape
and size on heat loss are illustrated in Figure 15-5. Information
required to estimate heat loss and freeze-up time for pipes and
utilidors is presented in Section 15.
All exposed utilidor surfaces should be insulated. Thermal
breaks or penetrations should be isolated from the pipes. Insulated
flanges and extra insulation at pipe anchors have been used. Additional
-------
8-19
insulation should be provided at appurtenances and vaults with larger
surface areas than the utilidor.
Freeze-protection provided for utilidor piping can be similar
to that for single pipes, and heat tracing can be used to maintain a
minimum temperature. Temperature control within the utilidor is
difficult when control heating or domestic hot water lines are included.
While soil cover and snow provide some natural insulation for
buried utilidors, shallow-buried, and above-ground piping and utilidors
are subject to extreme air temperatures. They must be designed for the
lowest expected temperatures and wind conditions. The design must take
into account:
a) short freeze-up time,
b) high maximum rate of heat loss,
c) high annual heat loss, and
d) expansion and contraction caused by changes in air
temperature or because the pipes have been drained.
The most critical expansion and contraction problems occur
when the system is started up, or when maintenance or emergencies
require that the system be shut down and drained.
Two conditions requiring calculations are the maximum movement
due to temperature changes and the maximum stress if movement is
restrained. With metal pipe, it is generally impractical to restrain
thermal movements. Maximum movement can be provided by the use of
compression or sleeve-type couplings, expansion joints, "snaking" the
pipe, or providing expansion loops. Most in-line expansion joints do
not perform adequately under freezing conditions; however, a
free-flexing bellows joint will operate even with residual water frozen
inside [16].
8.6 Maintenance
Repairs or replacement of piping and subsequent reclosure of
the utilidor must be considered in the cross-section design and
materials selection. Extra materials and components used within the
system must be available on-site. Standardization of components,
materials and design greatly facilitates maintenance.
-------
8-20
Below-ground utilidors should be the walkway-type for easy
access. Alternatively, no air space should be provided in shallow-
buried utilidors where the only access is by excavation. Above-ground
utilidors need not have walkways. Access to pipes and appurtenances is
facilitated by removable panels.
Vandalism, accidents, and weathering of exposed utilidors will
result in extra maintenance and must be considered in the materials
selection and design.
Repairs and service connections must be carried out only by
authorized personnel. The service conduit design, particularly the
connection to the utilidor, may be specified to ensure engineering and
aesthetic compatibility.
8.7 Costs
Capital costs, maintenance and heating requirements, and
service life are important factors in utilidor design and materials
selection [2,11]. Capital costs can be reduced by lowering standards;
however, this may be offset by higher operating and replacement costs.
Above-ground utilidors must be particularly rugged to contend with the
rigorous climatic conditions and vandalism. Numerous "low-cost"
utilidors have not survived their intended lifespan.
The capital costs for utilidors depend on the number, size,
and function of the enclosed pipes, the degree of prefabrication, the
foundation requirements and local conditions. The cost breakdown for a
two-pipe, wooden box utilidor on piles in Inuvik, NWT (Figure 8-l(b))
was:
17%
Engineering - design 7%
- field supervision 10%
Materials (including transportation) 33%
Construction 50%
Material costs for the carrier pipe utilidor in Figure 8-1(f,g) are
presented in Table A-3. The cost for the small utilidor in Figure
8-l(d) was approximately $230/m in 1977. The water and sewer wooden box
utilidor on piles constructed in a subdivision of Inuvik, NWT, in 1976,
cost $600/m for straight portions but average costs were $670/m and
-------
8-21
$805/m when the costs for vaults and road crossings were included.
Large utilidors with central heating lines are more expensive. Costs
for the utilidor in Figure 8-l(a) were over $1200/m.
Estimated annual maintenance costs in 1974 for utilidors in
Inuvik, NWT, ranged from $34 to $91 per service connection.
8.8 References
1. Tobiasson, W., "Utility Tunnel Experience in Cold Regions",
American Public Works Association, Special Report No. 41, pp.
125-138, 1971.
2. Gamble, D.J. and P. Lukomskyj, "Utilidors in the Canadian North",
Canadian Journal of Civil Engineering, _2(2):162-168, 1975.
3. Rogness, D.R. and W. Ryan, "Vacuum Sewage Collection in the Arctic,
Noorvik, Alaska; A Case Study", IN: Utilities Delivery in Arctic
Regions, Environmental Protection Service, Ottawa, Ontario EPS
3-WP-77-1, pp. 505-522, 1977.
4. Reid, B., "Some Technical Aspects of the Alaska Village
Demonstration Project", IN: Utilities Delivery in Arctic Regions,
Environmental Protection Service, Ottawa, Ontario, EPS 3-WP-77-1,
pp. 391-438, 1977.
5. Ryan, W., "Design Guidelines for Piping Systems", IN: Utilities
Delivery in Arctic Regions, Environmental Protection Service,
Ottawa, Ontario, EPS 3-WP-77-1, 1977.
6. Gamble, D.J., "Unlocking the Utilidor: Northern Uilities Design and
Cost Analysis," IN: Utilities Delivery in Arctic Regions,
Environmental Protection Service, Ottawa, Ontario, EPS 3-WP-77-1, 1977.
7. Fiberlite Products Co. Ltd, "Engineering Guide to Prefabricated
Utilidors", Edmonton, Alberta, n.d.
8. Slipchenko, W., (ed) , "Handbook of Water Utilities, Sewers, and
Heating Networks designed for Settlements in Permafrost Regions",
Northern Science Research Group, Department of Indian Affairs and
Northern Developement, Ottawa, Ontario, NSRG 70-1, 1970.
9. Leman, L.D., Storbo, A.L., Crum, J.A., and Eddy, G.L., "Underground
Utilidors in Nome, Alaska", Applied Techniques for Cold
Environments, American Society of Civil Engineers, New York, New
York, pp. 501-512, 1978.
10. Hoffman, C.R., "Above-ground Utilidor Piping System for Cold-Weather
Regions", Naval Civil Engineering laboratory, Port Hueneme,
California, Technical Report R734, 1971.
-------
8-22
11. Leitch, A.F. and G.W. Heinke, "Comparison of Utilidors in Inuvik,
NWT", Department of Civil Engineering, University of Toronto,
Toronto, Ontario, 1970.
12. Cooper, P.F. "Engineering Notes on Two Utilidors", Northern Science
Research Group, Department of Indian Affairs and Northern
Development, Ottawa, Ontario, 1968.
13. Porkhaev, G.V., "Underground Utility Lines", National Research
Council of Canada, Ottawa, Ontario, Technical Translation TT-1221,
1965.
14. Reed, S.C., "Field Performance of a Subarctic Utilidor", IN:
Utilities Delivery in Arctic Regions, Environmental Protection
Service, Ottawa, Ontario, EPS 3-WP-77-1, pp. 448-468, 1977.
15. James, F., "Buried Pipe Systems in Canada's Arctic", The Northern
Engineer, JJ(11):4-12, 1976.
16. Gilpin, R.R. and M.G. Faulkner, "Expansion Joints for
Low-Temperature Above-Ground Water Piping Systems", IN: Utilities
Delivery in Arctic Regions, Environmental Protection Service,
Ottawa, Ontario, EPS 3-WP-77-1, pp. 346-363, 1977.
-------
SECTION 9
WASTEWATER TREATMENT
Index
9 WASTEWATER TREATMENT 9-1
9.1 General Considerations 9-1
9.1.1 Treatment objectives 9-1
9.1.2 Period of design 9-1
9.1.3 Site selection 9-1
9.2 Wastewater Characteristics 9-2
9.2.1 Quantity 9-2
9.2.2 Quality 9-4
9.2.3 Flow variation 9-8
9.3 Unit Operations 9-9
9.3.1 Mixing 9-9
9.3.2 Sedimentation 9-9
9.3.3 Filtration 9-10
9.3.4 Gas transfer 9-10
9.3.5 Adsorption and chemical reactions 9-12
9.4 Unit Processes 9-12
9.4.1 Preliminary treatment 9-13
9.4.2 Primary treatment 9-13
9.4.3 Biological processes 9-14
9.5 On-site Treatment 9-30
9.5.1 Systems with discharge 9-31
9.5.2 Low or no discharge systems 9-31
9.6 Operation and Maintenance 9-33
9.6.1 Contents of O&M manuals 9-33
9.6.2 Design for O&M 9-34
9.7 Costs 9-34
9.8 References 9-37
9.9 Bibliography 9-38
-------
List of Figures
Figure
9-1 Viscosity Effects vs Temperature
9-2 Settling Detention Time vs Temperature
9-3 Two-cell Facultative Lagoon Flow Control
9-4 Stop-log Manhole and Lagoon Outlets
9-5 Dimensions of Lagoons
9-6 Power and Air Requirements for 3-m Deep Partial-Mix
Aerated Lagoon
9-7 Oxidation Ditch for Subarctic
Page
9-11
9-11
9-15
9-15
9-19
9-20
9-24
LIST OF TABLES
Table Page
9-1 Typical Per Person Sewage Flow 9-3
9-2 Institutional Sanitary Facilities in Cold Climates 9-4
9-3 Domestic Sewage Sourees 9-5
9-4 Estimated Sourees of Sewage Pollutants 9-6
9-5 Raw Sewage Temperatures at Treatment Facility 9-8
9-6 Variation in Solubility of Typieal Chemicals with
Temperature 9-12
9-7 Characteristics of Typical Aeration Equipment 9-20
9-8 Temperature Coefficients for Biological Treatment 9-22
9-9 Cost Comparison - Construction Camp Wastewater Treatment
Systems 9-26
9-10 Typieal Coliform Contents in Cold Regions Wastewaters 9-28
9-11 Typical Sludge Production Rates 9-29
9-12 Construction Costs - Partial-mix Aerated Lagoons 9-35
9-13 Relative Cost Factors - Partial-mix Aerated Lagoons 9-36
9-14 Construction Costs - Eielson AFB Aerated Lagoon 9-36
9-15 Estimated Annual Operation and Maintenance Costs -
Partial-mix Aerated Lagoons in Alaska 9-37
-------
9-1
9 WASTEWATER TREATMENT
9.1 General Considerations
This section is not a complete design text for wastewater
treatment systems. It gives special emphasis to those factors which are
unique to the cold regions. Reference is made to other manuals and
texts for basic sanitary engineering criteria and procedures. The
special factors for cold regions are not just responses to low
temperatures but also include: remote locations, logistical problems
during construction and operational resupply, permafrost and other
unstable site conditions, lack of skilled manpower, very high energy
costs, rapid turnover of operator personnel, and in some cases unique
environmental aspects.
9.1.1 Treatment objectives
Basic treatment objectives are not unique to the cold regions.
The fundamental purpose of wastewater treatment in all locations is
protection of human health. The next priority is to protect the
receiving environment. The guidelines, criteria and standards set by the
applicable regulatory agencies must be considered prior to undertaking
any design. Section 10 of this manual discusses impacts on the receiving
environment.
9.1.2 Period of design
The design life (Section 2.6.2) for waste treatment systems is a
function of the community or facility served. It can also be specified
by the regulatory and/or funding agencies. It is essential to determine
design life in the initial planning stages since this factor determines
the service life and treatment capacity requirements based on present and
future population.
9.1.3 Site selection
Most of the basic site selection criteria (i.e., advantageous
topography, suitable discharge point, etc.) are applicable to the cold
regions. Of special concern is the presence of permafrost under the
intended site. The presence of permafrost will strongly influence the
type of system chosen, and the economics of design and construction to
-------
9-2
ensure long-term stability of the system. Another factor requiring more
emphasis in cold regions is easy, continuous access to all critical
points in the system. Access roads and pathways must not be located
where snow drifting or icing will occur. The layout of the treatment
system itself must avoid creation of excessive snow drifts. If convenient
access cannot be provided, and easily maintained, then winter time
maintenance will probably not be performed. Distance requirements to
avoid nuisance conditions are generally applicable in both temperate and
cold regions. Lagoons should be no closer than 0.4 km (0.25 mi) from any
residence. All treatment systems may experience odour problems due to
operational difficulties, so any locations in close proximity to
habitations should be avoided.
9.2 Wastewater Characteristics
Wastewater characteristics in cold regions can be different from
those in temperate regions, both with respect to quantity and quality.
In general, the total quantity tends to be close to the amount of potable
water used by the community. Storm water is often excluded from the
collection systems. Infiltration is also not usually a factor in the
Arctic since collection systems are usually insulated and tightly sealed
to ensure thermal integrity. Communities such as Anchorage, Ak, and
others in the subarctic experience water wasting and infiltration, but
design considerations are not different from eonventional practice with
high flows and low organic loadings. The wastewater at most other cold
regions installations tends to be lower in volume and higher in strength
than at comparable facilities elsewhere. The wastewater from most cold
regions facilities is essentially domestic in character, with the
possible addition of laundry wastes and extra amounts of garbage from
institutional type kitchens.
9.2.1 Quantity
The requirements for total quantity of water needed are
discussed in Section 3 of this manual. The resulting per person sewage
flows depend on the type of installation and its permananee. Table 9-1
summarizes typical sewage flows for a variety of oold regions situations.
-------
9-3
TABLE 9-1. TYPICAL PER PERSON SEWAGE FLOW (L/person/d*)
1. Permanent Military Bases and Civilian Communities
a) > 1000 population with conventional piped water and sewage:
Thule Air Force Base, Greenland 303
College, Ak 265
Fairbanks, Ak 303
Ski resorts in Colorado and Montana 345
Average 300 L/person/d
b) < 1000 with conventional piped water and sewage:
Bethel, Ak 265
DEW Line, Greenland 208
Average 240 L/person/d
c) with truck haul systems, conventional internal plumbing:
Average 140 L/person/d
d) with truck haul systems, low flush toilets:
Average 90 L/person/d
e) no household plumbing, water tanks and honeybucket toilet:
Average 1.5 L/person/d
f) same as (e) above but with central bathhouse and laundry:
Average 15 L/person/d
2. Construction Camps
North Slope, Ak (1971) 189
"Typical" Canadian 227
Alaska Pipeline (1976) 258
Average 220 L/person/d
3. Remote Military with Limited Availability of Water
McMurdo, Antarctica 151
Barrow, Ak (DBS Sta) 114
"Typical" Army Field Camp 129
Average 130 L/person/d
* 1 L/person/d = 0.264 gallons/capita/day US.
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9-4
Separate facilities such as schools, laundries, restaurants and hotels
with conventional plumbing tend to have loadings similar to conventional
temperate zone practice.
Whenever possible, actual data from the specific site of
concern, or one similar, should be used to establish a design value for
per person flow. Where such data are not available, the average values
on Table 9-1 should be used for the appropriate type facility. These
values are all for permanent residential personnel. If an accurate
population count is not available, it should be assumed for design
purposes that there are 3.6 people per residence for military stations,
and 4.5 people for remote civilian communities. For day workers whose
residences are not serviced by the treatment system an allowance of 57
L/person per eight-hour shift should be made. In such estimating, the
same person should only be counted once, either at work or at home.
9.2.2 Quality
The physical, chemical and biological characteristics of sewage
in cold regions are strongly dependent on the type of installation and
the sanitary facilities provided. As described elsewhere in this manual,
these facilities can range from "honey bags" (as described in Section 13)
and buckets to complete equipment in the home or centralized for community
use. Table 9-2 summarizes the sanitary facilities provided at several
cold regions installations of the institutional type.
TABLE 9-2. INSTITUTIONAL SANITARY FACILITIES IN COLD CLIMATES
(units per person)
Toilets Urinals Sinks Showers
Thule AFB,
Greenland
P Mountain Radar,
Thule, Greenland
50 Man Winter
Camp Tuto , Greenland
Wainwright, Ak*
1/10
1/15
1/10
1/47
1/27
1/45
1/25
0
-
1/8
1/6
1/94
-
1/14
1/10
1/47
* See Section 11. This is a central facility for the village. Plans exist
to supplement with home water delivery and "honey" bag piokup.
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9-5
The grey water/black water concept Is used at the Wainwright,
Ak, central facility and should be considered wherever water conservation
is an issue (see Section 11 and Appendix B). Black water is considered
to be that related to human wastes from toilets, urinals, etc. Grey
water is then the remaining wastewater from showers, sinks, laundries,
ete. Table 9-3 summarizes the sources of domestic sewage from
communities and military field bases.
TABLE 9-3. DOMESTIC SEWAGE SOURCES (% of average daily flow)
Category
Data Source
Bailey [1]
Witt [2]
Jesperson [3]
Given and Chambers [4]*
Flaek [5]
Snoeyink [6]
U.S. EPA [7]
AVERAGE
Toilet,
Urinal
33
26
41
41
33
39
43
37
Shower,
Sinks
33
29
37
16
37
34
38
32
Kitchen
19
14
11
16
4
7
12
12
Laundry
15
30
11
27
26
20
7
19
*Adjusted for conventional toilets. Vacuum units used in study.
Field Army Bases (1000-6000 pop)
(% of average daily flow)
Photographic
Aireraft Washrack
Vehicle Washraok
Hospital
Toilets, Shower, Sinks
Kitchen
Laundry
5
9
3
1
60
6
16
100%
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9-6
9.2.2.1 Concentration of pollutants. The concentrations of wastewater
constituents will vary with the amount of water used and the type of
facilities employed. However, the actual mass loading of organics and
related substances should be relatively constant on a per person basis.
Table 9-4 gives estimated mass values for the major domestic wastewater
sources. The values are based on a comparative analysis of a number of
data sources. The final item, "institutional garbage grinders", reflects
the common practice at military stations and many construction camps of
grinding most of the kitchen wastes for inclusion in the wastewater
stream.
TABLE 9-4. ESTIMATED SOURCES OF SEWAGE POLLUTANTS
(g/person/d)*
Source BOD5 SS Total N Total P
Toilets
Bath /shower
Laundry
Kitchen
Subtotal
Institutional
Garbage Grinders
Total
60.8
5.33
7.92
16.8
90.8
59.0
150
85.2
5.12
7.70
10.9
109
58.8
165
14.7
0.31
0.23
0.49
15.7
1.31
17.0
1.67
0.04
0.67
0.49
2.83
0.95
3.78
*lb/capita/day = (g/person/d) T 454.
All the values in Table 9-4 are independent of the amount of
water used for a particular activity. Combining these values with data
in Tables 9-1 and 9-3 or other sources will allow determination of
concentrations for a particular case. Two examples follow:
a) 200-man construction camp, all conventional facilities,
central dining and kitchen with garbage grinder.
From Table 9-1: Assume flow = 220 L/person/d.
-------
9-7
From Table 9-4: g/person/d
BOD5 SS N P
Totals include toilets, baths,
laundry, kitchen, garbage 150 165 17 3.8
x 200 people = 30 000 33 000 3400 755
Total Flow: 220 x 200 = 44 000 L/day.
Concentrations: BOD5 30 000 * 44 = 680 mg/L
SS 33 000 f 44 = 750 mg/L
N 3 400 * 44 = 77 mg/L
P 755 T 44 = 17 mg/L
b) Small community, truck haul, internal plumbing low volume
flush toilets (assume 100 people).
Table 9-1: flow = 90 L/person/d.
Table 9-4: g/person/d
BOD5 SS Total N Total P
91 109 16 3
Design concentrations:
mg/L = g/person/d T L/person/d x 100 mg/g
BOD5 1011 mg/L
SS 1211 mg/L
N 177 mg/L
P 33 mg/L
9.2.2.2 Temperature. The temperature of the raw wastewater entering
the sewage treatment plant can be an important physical characteristic.
The efficiency of most unit operations and processes can be strongly
influenced by temperature. Temperature control is also necessary to
prevent unwanted freezing either in the system or at the point of final
discharge.
The energy level represented by moderate (10°C) to high
incoming sewage temperatures should be considered as a resource. The
treatment system and its protective elements should be designed to take
full advantage of this available energy. For example, the municipal
treatment plant in Fairbanks, Ak, extracts energy from the effluent via a
heat pump and this is used to heat the entire facility.
-------
9-8
The temperature of raw wastewater is a function of the raw water
temperature, the water and sewage system design and characteristics, the
use, number and plumbing (hot water) of buildings serviced, and the
ambient temperatures. Some values for raw wastewater temperature are
presented in Table 9-5.
TABLE 9-5. RAW SEWAGE TEMPERATURES AT TREATMENT FACILITY (°C)
Location Winter Summer Notes
Fairbanks, Ak
Fairbanks , Ak
College, Ak
Eielson, AFB, Ak
Juneau, Ak
Kenai , Ak
Homer , Ak
Dillingham, Ak
Craig, Ak
Kake, Ak
Soldofna, Ak
Eagle River, Ak
Eagle River, Ak
0
11.8
18.9
21.7
2.2
8.0
3-5
3
3-4
5
4
5
9
2.8
10.9
18.3
20.7
8.9
10-14
9-10
8-9
Individual wells
Water main at 15°
Sewers in heated
Sewers in heated
April
January
December
Initial operation
services
After 4 years
C
utilidor
utilidor
, few
Inuvik, NWT
Whitehorse, YT
Clinton Creek, YT
3-15
17
23
22
Water main bleeders
Emmonak , Ak
Alaska
Hay River, NWT
9.2.3 Flow variation
28
20-24
10-15
Central facility, grey
water only
Construction camps
( Alyeska)
Airport facility
Institutional facilities in cold regions, such as military
stations and construction camps, tend to have strong flow variations
because a large portion of the population responds to the same schedule.
The peak flow will usually occur in late afternoon when personnel are
using the bath and laundry. Two such peaks will occur at those installa-
tions operating on a continuous two-shift, 24-hour cycle. The peak daily
flow rate for design purposes should be three times the average daily
rate for institutional facilities.
-------
9-9
Civilian communities and similar residential areas have less
sharply defined flow variations. In general, a single major peak,
approximately at mid-day will occur. The time is dependent on trans-
mission distance from the homes to the treatment system. The daily peak
flow rate of these communities should be taken as two times the average
daily rate. The U.S. Public Health Service uses a factor of 3.5 for
designs in small communities (see Section 3.4).
Minimum flow rates are important to the design of grit chambers,
monitoring devices, dosing equipment, etc. A minimum rate equal to 40
percent of the average rate should be used for design purposes.
9.3 Unit Operations
Practically all of the unit operations used in wastewater
treatment are affected by temperature through viscosity changes in the
water and/or changes in chemical reaction rates. An analysis during
early design stages is necessary to predict the thermal status of major
components in the system. If warm sewage is expected and the entire
system is to be housed in a heated building, then conventional temperate
zone practice can be used. If cold sewage is expected or significant
temperature changes are predicted within the system, then adjustments
will be necessary in the design of unit operations as described in
subsequent sections.
9.3.1 Mixing
Mixing is an important function in waste treatment. It is
required for flocculation, for the continual suspension of solids in
liquids such as the mixed liquor in activated sludge, and for dissolving
solids. All of these mixing activities are strongly dependent on
temperature because of changes in the viscosity of the liquid. Figure
9-1 can be used to make the necessary adjustments in design criteria for
temperature-induced viscosity changes. Further information on mixing can
also be found in Section 4 since the general requirements are the same
for water and wastewater.
9.3.2 Sedimentation
The settling of discrete particles in water is affected by the
viscosity of the water. This is a factor in grit chambers and in primary
-------
9-10
settling tanks when flocoulant chemicals are not used. Detention times
must be increased to compensate for lower settling velocities in colder
water. The multipliers on Figure 9-1 ean be used to adjust design
detention times. The temperatures shown are for the fluid and not the
general air temperature. Alternatives to adjusting design detention
times include housing the tanks in a heated enclosure and/or preheating
the incoming fluid.
The settling of higher concentration flocculant particles is not
as strongly affected by temperature. As shown on Figure 9-2, at concen-
trations of 2000 mg/L or less, temperature-induced viscosity effects are
quite strong. At 6000 mg/L and higher, the concentration of particles
present has a greater influence than fluid temperature. The multipliers
shown on Figure 9-2 can be used for the design of settling tanks and
thickeners. Values for sludge concentrations not shown can be determined
by interpolation. Figure 9-2 demonstrates that settling units, such as
upflow clarifiers, tube settlers, eta, which are designed for relatively
high sludge concentrations, will require the least size adjustment for
low-temperature operation.
Density currents must also be considered in the design of
settling tanks and thickeners. If the incoming fluid is significantly
different in temperature than tank contents, short eircuting and/or
excess solids loss may occur. Protective elements should be employed if
necessary to maintain the temperature of tank contents as elose as
possible to that of the incoming fluid.
9.3.3 Filtration
Filtration of wastewater is affected by temperature-indueed
viscosity changes. The multiplier values from Figure 9-1 should be used
to reduce filtration efficiency. Further details on filtration oan be
found in Section 4 since basic criteria are common for both water and
wastewater.
9.3.4 Gas transfer
The solubility of gases in water increases as the temperature
decreases. Air, oxygen, and ehlorine are the commonly used gases in
wastewater treatment. The efficiency of aeration and other gas transfer
-------
9-11
1.75r
1.00 -
0.00
f\ i i
5 10 15
Temperature (°C)
. . ^
20
FIGURE 9-1. VISCOSITY EFFECTS VS TEMPERATURE
0)
"3.
2.00
1.75 *
1.50
35
40
Temperature (°F)
45 50 55
60
Temperature (°C)
FIGURE 9-2» SETTLING DETENTION TIME VERSUS TEMPERATURE
-------
9-12
operations should, in theory, be greater with low temperature wastewaters.
However, the viscosity of the water also increases as the temperature
decreases. This decreases the number of contacts between gas bubbles and
water molecules. These two factors tend to compensate for one another,
so the net practical effect is little improvement in overall gas transfer
efficiency with low temperature wastewaters. Section 4.2.9 provides
additional detail on aeration.
9.3.5 Adsorption and chemical reactions
Adsorption occurs in biological processes as well as in physical/
chemical treatments with activated carbon. The rate of adsorption, as
defined by the Gibbs equation, is inversely proportional to temperature,
so adsorption should be more rapid at low temperatures. However, the
increased viscosity of the water at low temperatures has the same effects
as described above so there is no practical improvement in efficiency.
Both metabolie and chemical reaction rates tend to be slower at
low temperatures. These effects must also be considered in preparing
chemical solutions for use in wastewater treatment. The solubility of
most chemicals decreases as the water temperature is lowered. Table 9-6
gives some representative values for typical treatment chemicals.
9.4 Unit Processes
Processes for preliminary, primary, secondary and advanced waste
treatment are based on the unit operations or combinations thereof
previously discussed. This section will only consider those faetors of
special significance in eold climates.
TABLE 9-6. VARIATION IN SOLUBILITY OF TYPICAL
CHEMICALS WITH TEMPERATURE (grams/litre)*
Temperature
Chemical
Alum
Ferrous sulphate
Sodium hydroxide
Calcium hypochlorite
0°C
723
60
287
215
20°C
873
120
527
228
* grams/litre x 0.00834 = Ib/gal
-------
9-13
9.4.1 Preliminary treatment
This can include screening, grit and scum removal and grinding
or comminution. The latter can be a component, such as grinder pumps, in
pressure sewage transmission systems discussed in Section 7. The use and
proper maintenance of grease traps at appropriate locations, e.g., institu-
tional kitchens, is absolutely essential for the successful operation of
treatment processes as well as collection systems in cold regions.
9.4.1.1. Screening. The basic design for trash racks and bar screens
is not different in cold climates. Since storm waters are usually
excluded from cold regions sewer systems the channel design for screens
or racks can be based on wastewater flow rather than storm water flow.
In the arctic and subarctic it will be necessary to enclose the facility
in a shelter to avoid icing problems and provide easy access for opera-
tion and maintenance. If warm sewage is expected it may not be necessary
to provide supplemental heat for an insulated enclosure. Condensation
and icing may occur on the inner surfaces of exterior walls so materials
and coatings should be selected accordingly and mechanical or electrical
controls located elsewhere.
9.4.1.2 Grit and scum. Designs for grit chambers, flotation chambers,
and grease traps are also similar to temperate zone practice. Detention
times should be increased for low temperature sewage as described in
paragraph 9.3.2. Protective enclosures will be similar to those
described above under 9.4.1.1. Problems with grease traps are not unique
to institutional facilities in cold climates, but special attention
should be given to their location and proper maintenance.
9.4.2 Primary treatment
The design detention time for settling during primary treatment
will require adjustment as described in paragraph 9.3.2. If soil
conditions permit, settling tanks should be designed in the conventional
manner as partially buried structures. The presence of permafrost,
particularly as ice-rieh, fine-textured soils, will require above-ground
tanks and/or special foundations. Temporary covers are recommended for
buried tanks for winter operation in the Arctic and subarctic. Tanks
-------
9-14
above grade will require sidewall insulation and covers, or enclosure in
a protective structure.
9.4.3 Biological processes
Systems which have been successfully used in cold climates
include: lagoons, both facultative and aerated, activated sludge
variations, and attached growth systems. Each has special requirements
for successful cold region performance.
9.4.3.1 Facultative lagoons. Where sufficient land area and suitable
soil conditions exist, facultative lagoons are probably the most
cost-effective alternative for cold regions. The major responsible
factors are simplicity, and economy of construction and operation.
Facultative lagoons should be designed for a BOD loading of up
to 3.7 kg/ha. Winter performance in cold climates is reduced because of
ice and snow cover and low temperatures and is roughly comparable to
primary treatment. Total retention during this period is often required.
Controlled discharge from such ponds in the late spring and early fall is
a common practice in Canada and the north central U.S. Two or three
cells are commonly used to avoid short circuiting. Figure 9-3 illustrates
a typical two-cell arrangement. Figure 9-4 illustrates the use of a
stop-log manhole for depth control.
The amount of ice cover to be expected on a facultative lagoon
can be predicted by the method described in Section 5. If sufficient data
are not available for such calculations a depth of 1 m should be assumed
for most subarctic locations. The design depth should be based on winter
conditions and allow 30 cm of freeboard, plus the ice thickness, plus 1.5
m from the underside of the ice to the lagoon bottom. Maximum depth
during the summer period would be 1.5 m as maintained by the stop-log
manhole.
Supplemental aeration may be needed for sueh lagoons in very
special oases. Examples might be where fish canning, animal slaughter or
other food processing imposes a brief but intense loading on the lagoon
during the summer months. In these cases small floating aerators or
similar devices can be used during the period of concern and removed for
the balance of the year.
-------
9-15
Raw sewage
Effluent
PIPING DETAIL
Cell 1
• Valve
Cell 2
Stoplog manhole
(Figure 9-4)
r 1
—*Y~
T
SERIES OPERATION
PARALLEL OPERATION ISOLATE AND DISCHARGE
FIGURE 9-3. TWO-CELL FACULTATIVE LAGOON FLOW CONTROL
Valve box and valve stem extension
• Frost heave protection |ce cover.
Gate valve
Maximum frost penetration
Insulated, electric heat traced pipe
2-3
Upturned elbow -
Anchor block •
Frost heave protection if required
Insulated cover
Ice cover •
•'•'•'.'•' .•' .".'••'/ '• '/0v]^NSi^i-z---r--------
L" ' -."-.• "-:oy??%cL.-_---r-_H
Concrete pad or rip-rap
Gate valve
40mm
Calking as required
Adjustable stop logs
Detail
FIGURE 9-4. STOP-LOG MANHOLE
-------
9-16
Standard temperate zone construction techniques can be used
except where permafrost is present. Permafrost consisting of fine-
textured, ice-rich soils should be avoided because thawing can result in
failure or at least frequent repair and restoration of dikes and berms.
Lagoons can be constructed in permafrost that is physically
stable after thawing. In this case a two-stage operation has advantages
if time permits. The first stage is limited to stripping the vegetation
and topsoil from the lagoon area. Actual eonstruetion can begin when
thawing has progressed to a suitable depth. Construction techniques for
dikes and berms, and the use of lining materials, are the same as
described in Section 5 for water storage.
The shape of the lagoon can affect performance by influencing
short circuiting and mixing. In general, square or rectangular cells
where the length is not more than three times the width are preferred.
The corners should be rounded in both cases. On occasion it is possible
to take advantage of existing topography and use a natural depression or
swale with minimum construction; even the use of an existing pond might
be considered.
9.4.3.2 Aerated lagoons. These systems require less land area, more
energy and more operational and management attention than facultative
lagoons. Systems in use in eold climates range from low-intensity
systems where algae may still be a factor to high-rate well-mixed units
whieh are really a variation of aetivated sludge. Only the partial-mix,
low-intensity systems will be considered in detail in this section
because of their lower energy and O&M requirements.
Basic process design criteria are similar to those used in
temperate zones. Design is based on:
where: Se = effluent BOD (mg/L),
S0 = influent BOD (mg/L),
t = detention time (days) = —,
Q
-------
9-17
V = volume of basin,
Q = daily flow,
K = overall reaction coefficient (base e).
winter (0.5°C) = 0.14
summer (16-20°C) = 0.28
For basins in series, the equation becomes:
Se = 1 (9-2)
S _ , KtvN
o (1 + —)
where: N = number of basins.
This can be transposed to:
Kt = N
N
- 1
(9-3)
Using the specified K values, the BOD values required for a
particular design, and a range of N values (1-4), equation (9-3) can be
repetitively solved to determine the optimum number of basins. In
general, winter conditions govern the number and size of basins, and
summer eonditions are critical to adequate oxygen transfer.
The effective treatment volume must reflect ice cover in the
winter and sludge accumulation on a year-round basis. Ice will not
form continuously over the entire surface. Even in extreme weather there
will be small areas of open water where air will bubble to the surface
from the submerged aeration system. Aerated lagoons in central Alaska
(freezing index >2800°C-days) have been designed for a 30-om
winter iee cover. A single-cell lagoon near Anchorage, Ak, (freezing
index 1250°C-days) receiving warm sewage has a 5-om observed winter
ioe cover. If specific values are not available, an assumed factor of
15% for depth of ioe cover is recommended. A factor of 5% is commonly
used to allow for sludge accumulation on the bottom. The lagoon volume
required for winter treatment must be in addition to both of these
factors.
-------
9-18
A design for minimal heat loss would include vertical sidewalls
but this increases construction costs. Sloping sidewalls (1:2 or 1:3)
are most common. A square configuration with rounded corners is recom-
mended to minimize heat loss and hydraulic short circuiting. The
dimensions of such a basin can be determined as shown on Figure 9-5.
Some form of submerged aeration is generally used; floating
aerators and other surface devices create icing problems. Inlet and
outlet structures are similar to those described previously for
facultative lagoons. The oxygen requirements for aeration design are
based on summer conditions when biological activity is at maximum rate.
For partial-mix lagoons the oxygen required is usually specified as
double the organic loading:
02 = (2) (BOD) (Q) (10-6)
where: 02 = kg/day oxygen required,
BOD = influent BOD5 (mg/L),
Q = flow (L/d).
Under standard conditions, air contains approximately 0.28
kg/m3 oxygen.
. J , 3/ . (2) (BOD) (Q) (10~6)
Air Required (nrYs) = L^d—
(E) (0.28 kg/m3)(86 400 s/d)
8.27 x IP"11 (BOD) Q
E
where: E = aeration efficiency,
m3/s x 35.31 = cfs.
The aeration efficiency depends on a number of factors such as
depth of basin, type of diffuser, mixing turbulence and basin
configuration. The E value for partial-mix lagoons with submerged tubing
is approximately 16%. For a typical case with a raw sewage BOD of 240
mg/L and a flow of 10^ litres per day, the air requirements would be:
- (8.27 x 1Q-H)(240 mg/L)(105 L/d)
A.
Air
= 0.012 m3/s.
-------
9-19
Calculation of basin volume for any rectangular basin
with sloped sides and round corners
Sd
— a »'
b
\
Volume = V = d [(a + Sd) (b + Sd) + .0472 S2 d2]
Note: The last term (.0472 S2 d2) can
be dropped for preliminary estimates
FIGURE 9-5. DIMENSIONS OF LAGOONS
-------
9-20
Figure 9-6 illustrates the air and power requirements for a 3-m
deep partial-mix aerated lagoon.
Organic load (kilograms BOD5/day)
100 200 300
20
15
03
I
55 10
J3
QQ
800
00
"co
600 \
ON
400 |
03
CT
03
200 <
1000
2000
Population
3000
4000
FIGURE 9-6. POWER AND AIR REQUIREMENTS FOR 3-m DEEP PARTIAL-MIX
AERATED LAGOON
Table 9-7 summarizes the characteristics of typical aeration
equipment for cold climate partial-mix lagoons. An ice cover will form
over such lagoons in the winter. However, eve.n under extreme temperature
conditions there is sufficient open water for the applied air to exhaust
to the atmosphere. Protective and heated housing will be required for
blowers, pumps, and related controls. Such enclosures must provide an
external air intake for the blowers but preheating of the air is
unnecessary.
TABLE 9-7. CHARACTERISTICS OF TYPICAL AERATION EQUIPMENT
02*
Equipment (kg, Standard Conditions)
Common Depth**
(m)
Submerged Tubing
Air Gun
Helical Diffuser
0.3-1.0/100 m
0.4-0.7/unit
0.5-1.9/unit
1-3
3.5-6
2.5-4.5
-------
9-21
Summertime algae blooms will occur in these partial-mix ponds
throughout the Arctic and subarctic. The requirements of federal and/or
local regulatory agencies with respect to removal of algae must be
determined prior to design for a specific site. Techniques for algae
removal are available, and the criteria are not unique to cold regions.
Addition of algae-removal equipment to an aerated lagoon will increase
costs and complexity, and possible resit in the selection of some other
basic process for treatment. Typical cost relationships for lagoons in
Alaska are given in Section 9.7.
9.4.3.3 Activated sludge variations. Systems in use in cold regions
include conventional and oxygen activated sludge, contact stabilization,
extended aeration and oxidation ditches.
Many of these systems are enclosed in heated structures and
receive warm sewage on a year-round basis. Basic process design criteia
for these situations are no different than conventional temperate zone
practice.
Speecial attention must be given to system details, appurtenances
and process controls. The humidity inside such buildings will be quite
high due to exposed water surfaces'. Condensation and icing can occur on
inner surfaces of exterior walls, doors, and windows. Control panels and
similar elements should be located away from such surfaces to avoid water
and/or ice damage.
Ventilation of such structures is necessary, but the impact of
the exhause on the adjacent community must be considered. Ice fog can be
created under extreme conditions, resulting in aesthetic and safety
problems. Dehumidification or heat recovery with induced condensation
will control the problem.
Systems that are exposed to the weather and/or expect to receive
low-temperature wastes may require modification of basic design criteria
in addition to the general factors discussed above.
Conventional or oxygen activated sludge and contact
stabiliation . These types of systems will probably be enclosed, but in
either case they may receive low-temperature wastewaters. Reaction rate
coefficients are presented in Table 9-8 for use in the equation:
-------
9-22
TABLE 9-8. TEMPERATURE COEFFICIENTS FOR BIOLOGICAL TREATMENT
Temperature Range
Process
Oxidation Pond
Facultative Lagoon
Anaerobic Lagoon
Aerated Lagoon
Activated Sludge
Extended Aeration
Trickling Filter (conventional)
Biofilter (plastic media)
Rotating disc
Direct filter recirculation
Final effluent recirculation
Final effluent recirculation
6
1.072 - 1.085
1.06 - 1.18
1.08 - 1.10
1.026 - 1.058
1.00 - 1.041
1.037
1.035
1.018
1.009
1.009
1.032
°C
3-35
4-30
5-30
2-30
4-45
10-30
10-35
10-30
13+
5-13
Significant ice formation must be avoided in the aeration compart-
ments of these systems. An ice cover will inhibit atmospheric aeration
and will entrap mixed liquor solids. Both factors may reduce treatment
efficiency. Tank design should provide minimum exposed surface area.
Evaporation from liquid surfaces and the cooling effect of the wind are
major factors in winter time heat loss. An unheated protective shelter
over the tanks will reduce both and allow satisfactory performance. An
alternative would be temporary tank covers and wind breaks during the
winter period only.
Settling tanks and clarifiers associated with these systems
should receive protection to reduce heat loss and inhibit formation of
density currents. Protective elements in the northern temperate zone can
be limited to those required for operator safety (prevent icing on walls,
ladders, etc.), and to overflow weirs and scum removal points where
freezing is most likely to occur.
Extended aeration systems are available as prefabricated "packaged*
units of up to 3800 m^/d capacity. Smaller sizes are also available
completely installed in a prefabricated shelter ready for direct installa-
-------
9-23
tion. Basic process design criteria are comparable to temperate zone
practice if warm sewage is to be received at an enclosed and heated
treatment unit.
It is not necessary to provide a continuously heated building to
maintain treatment efficiency; operator convenience and comfort are the
only justifications for such energy inputs. If the incoming raw sewage
is about 10°C or warmer there is sufficient heat in the liquid to
sustain the process. Protective elements (i.e., tank covers, burial,
wind breaks, unheated shelters) are useful to reduce heat losses. A
stand-by heat source is also recommended for emergency situations.
Extended aeration systems have been successfully operated with
mixed liquid temperatures of 1° to 5°C, producing effluent EOD^ and
SS of secondary quality. Mixed liquor concentrations tend to increase
more rapidly under these conditions so more frequent sludge wasting is
required. Design organic loadings (F/M ratio) of up to 0.08 g BOD/g
MLSS/day and MLSS concentrations of 3000-4000 mg/L are recommended for
low-temperature operation. Pumps, motors, blowers, external piping,
valves and similar appurtenances require protective enclosures and heat.
Design of these units for military and construction camps must
consider the potential for intermittent loading and strong fluctuations
in population. Equalization tanks can damp out strong daily variations
in flow. Where regular population changes are expected the design can
provide two or more smaller units for parallel operation under peak
conditions. Only one unit would be operated under low flow conditions.
These small-scale systems are particularly sensitive to situa-
tions created by water system bleeding and/or infiltration in the community.
Either ean hydraulically overload the system. ' The potential for these
conditions must be evaluated prior to design. It must also be verified
that the capability will exist to operate the type of system proposed.
Oxidation ditches have been successfully used in subarctic
Alaska. Basic process design criteria are similar to practice elsewhere.
Design for low-temperature operation should conform to extended aeration
criteria given above.
Modifications to temperate zone configurations are required to
reduce heat loss. As shown on Figure 9-7, vertical side walls and a thin
-------
9-24
Brush housing (see detail)
SECTION A-A
Co
'j"',»
•.;'•;' S.
3 '•
' •",'
o''v:
nc
;rete — ^
WLV
,_~~__~_~~— ~~_ ~~_ ~~_ ~
^Z-Z^-ZO
»-,
V
-z-z-z-z-z-z
q
. i) ' .'• '•*••„'.- '&
o'- ' , '.'
/aV
BRUSH HOUSING
Air vent
Neoprene skirts
WLy
-_-: Flow
FIGURE 9-7. OXIDATION DITCH FOR SUBARCTIC
vertical centre island reduce surface area and heat loss in the ditch.
Also shown on the same figure are the protective housing neoprene
skirts to prevent icing around the brushes. The clarifier units for such
systems should be enclosed but need not be heated. Cautions regarding
location of controls, etc., on exterior walls should be observed.
These systems are potentially applicable over the same range
previously indicated for extended aeration. They can be constructed
on-site and attempts at prefabrication have been made in the past in the
smaller sizes. All the cautions and limitations previously indicated for
extended aeration apply.
9.4.3.4 Attached growth systems. These would include rotating
biological discs, trickling filters, and similar devices with plastic,
rock, or wooden media. Since they depend on a thin film of water for
treatment they are susceptible to freezing. Units are, therefore,
generally enclosed in a heated structure. However, if low-temperature
wastewater is expected, the reaction rate coefficient from Table 9-8
should be used for design. Clarifier tanks need not be heated but should
be protected as described in pervious paragraphs of this section.
-------
9-25
Configuration of these systems follows temperate zone practice,
with some form of preliminary clarification and final settling with
recirculation common. Basic process design criteria are not unique for
cold climates. Adjustments to the design rates for low-temperature
wastewater should be made using the 6 values in Table 9-8.
Limited experience with disc systems to date tends to indicate a
greater level of system reliability with a lesser level of energy and
operator skill compared to complete-mix biological or physical/chemical
treatments. They can also be designed to provide nitrification in
addition to BOD and suspended solids removal.
9.4.3.5 Physical/chemical processes. The biological systems described
in previous paragraphs are capable of secondary treatment at best.
Physical/chemical systems, depending on the units in the process, can be
designed to produce almost any level of effluent quality desired. In
most applications they are used to achieve a high level of organic and
solids removal and/or nutrient removal. As in temperate zone practice,
they can either follow preliminary biological treatment or the entire
process train can be physical/chemical. It is conventional practice, in
all climatic zones, to install such units in heated buildings. Basic
process design is not, therefore, unique to cold regions, except when
low-temperature sewage is expected. Adjustments can then be made as
described in Section 9.3. An alternative is to warm the raw sewage in an
equalization tank in a heated structure. This will stabilize and enhance
performance of the system.
These units were selected for most of the camps during construc-
tion of the Alaska pipeline. Advantages claimed included: minimum space
requirements; minimum site impact during construction and restoration;
consistant high quality performance; and, operation could be matched to
varying flow or organic loading. Disadvantages observed during operation
included very high costs due to intense labour requirements, chemicals
and energy.
Estimated chemical costs for a typical 95 m^/d system ranged
from $0.32 to $2.33 per 1000 L. A comparison of annual costs, manpower
and energy is given on Table 9-9. The two systems compared are capable
-------
9-26
of producing generally equivalent effluents since the physical/chemical
units were only designed for organic (i.e., BOD) and suspended solids
removal, not nutrients.
TABLE 9-9. COST COMPARISON - CONSTRUCTION CAMP WASTEWATER
TREATMENT SYSTEMS* (1976 $)
Process
Extended Aeration-'-
Capital Equipment
Parts and Chemicals
Physical Chemical^
Capital Equipment
Parts and Chemical
Amortized
Annual Costs
Equipment and Mtl.
($1000)
30.6
11.4-14.8
31.3
19.4-71.9
Manpower Energy
(MH/day) (kW/day)
5-10 180
24 400
* 95 m3/d for Alaska pipeline construction camps
with: 6-hr equalization, pumps, blowers, aerobic digestor,
chlorination. 5-year life @ 15%.
2
with: 12-hr equalization, pumps, blowers, centrifuge, chemical feed,
chlorination. 5-year life @ 15%.
Based on experience to date, physical/chemical treatment should
only be considered if very high effluent requirements exist in conjunc-
tion with site conditions that preclude other forms or combinations of
treatment.
9.4.3.6 Land treatment processes. These concepts are capable of very
high levels of treatment depending on the process and operational mode.
In addition to normal organics and suspended solids, removal of
nutrients, metals, bacteria and virus are possible.
Basic process design criteria are similar to those used in
temperate regions since these already include factors for general weather
conditions and low-temperature periods. The land treatment component is
usually preceeded by some other form of treatment, typically a lagoon.
Depending on the concept, additional storage may be required for
inclement weather or other seasonal constraints. Treatment and storage
functions can be combined in a multi-cell facultative lagoon.
-------
9-27
The practical range of land treatment options is limited in
permafrost regions. Shallow permafrost and extreme winter temperatures
limit the horizontal and vertical movement of water in the soil profile.
During the summer it would be possible to operate an overland flow
process under the conditions described. Basic process criteria would be
similar to temperate zone practice. During the operational period high
removal efficiencies for BOD, SS, nitrogen and metals are possible with
moderate removal of phosphorus expected. However, an alternate discharge
or storage would be necessary for most of the year.
Slow rate land treatment is feasible anywhere in the cold
regions where silviculture or agriculture is practiced. The wastewater
is sprinkled or spread on the ground surface and the vegetation is a
component in the treatment process. The percolate can be recovered for
reuse or allowed to move into the groundwater. The operational season is
limited to the period of unfrozen surface soil conditions. Peak perfor-
mance is attained during the growth period of the vegetation. Percolate
of drinking water quality can be achieved in a properly designed and
operated system. Alternative discharge or storage would be required
during the period when surface soils are frozen.
Rapid infiltration has the greatest promise for cold climates.
It depends on relatively high rate applications on relatively coarse-
textured, free-draining soils. These can be found throughout cold
regions in alluvial river valleys and coastal areas. Very high BOD, SS,
bacteria, virus and phosphorus removal can be achieved, and moderate
nitrogen removal depending on the mode of operation. Rapid infiltration
can also be operated on a year-round basis in some locations so extensive
storage is not needed. Treatment to primary effluent quality is needed
to avoid rapid clogging of the soil surface. A facultative lagoon would
more than suffice. Operation is similar to percolation ponds except that
a number of beds, or cells, are alternately flooded and dried to improve
treatment and prevent clogging.
A thorough site investigation is required to ensure that the
applied wastewater will enter the soil and move down and away from the
application site. Experience is limited in the arctic and subarctic and
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9-28
optimum criteria are not available. Pilot tests are recommended for
large-scale operations. Experience in northern New England suggests a
value of approximately 111 000 m^ per year as a conservative estimate
of annual application. That would require one hectare of basin surface
for every 750 m^/d of wastewater flow.
9.4.3.7 Disinfection. The need for and the degree of wastewater dis-
infection to be achieved, and often the agent to be used, are specified
by the regulatory agencies of concern. Typical coliform contents of cold
regions wastewaters are shown in Table 9-10. Chlorination is the most
commonly used technique in the cold regions but lime has also been
tested. Basic process criteria are similar to temperate zone practice
with respect to contact time and properly baffled chambers to prevent
short circuiting. The selection of either gas or hypochlorite as the
chlorine source and the related safety measures also follow standard
practice as modifed by logistical resupply problems for many cold regions
locations.
TABLE 9-10. TYPICAL COLIFORM CONTENTS IN COLD REGIONS WASTEWATERS*
Waste Type
Weak Sewage
Holding Tank Effluent
Honey Bags
Lagoon Effluent
Typical
Location
Dawson
Aklavik
Aklavik
Inuvik
L/person/d
5915
68
1.3
545
Total Coliforms
number/100 ml
1.0 x 105
1.0 x 107
5 x 108
1.0 x 105
* Source: International Environmental Consultants, Report on
Alternatives to Disinfection (1978).
Erosion type chlorinators have been used at small remote facili-
ties in Alaska. It is sometimes difficult to maintain a specified
dosage but they offer operational simplicity. They should be housed in a
separate compartment constructed of noncorroding materials, along with the
tablet supply in a sealed container. In the past, extreme corrosion of
metals and mechanical parts has occurred when exposed to the humid
atmosphere of an enclosed treatment plant building.
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9-29
Effluents from lagoons and other exposed treatment units will be
at or near 0°C under extreme winter conditions. Some thermal protec-
tion for the contact chamber is therefore essential.
9.4.3.8 Sludge. Only in-plant sludge management is discussed in this
paragraph. Final sludge disposal is described in Section 13.
Large-scale conventional facilities, and those operating within a
heated environment can be expected to produced sludge at rates similar to
conventional temperate zone practice. Typical values are summarized in
Table 9-11.
Aerobic treatment systems designed for low-temperature operation
will tend to generate sludge at a rate similar to moderate temperature
units but, because of lower metabolic activity, cannot oxidize it as
fast. There will, therefore, be a higher rate of accumulation in the
winter than experienced in conventional practice. As a result, winter
TABLE 9-11. TYPICAL SLUDGE PRODUCTION RATES*
Process Dry Solids Solids Content
g/person/day of Wet Sludge
Primary Settling
Trickling Filter
Secondary
Primary plus T.F.
Secondary
Primary plus high-
rate Activated Sludge
Conventional Activated
Sludge Secondary
Primary plus conventional
A.S. Secondary
Extended Aeration
Secondary
Lagoons
54
18
72
82
32
86
40
60
6
4
5
5
0.5-1
2-3
2
20**
* Average 24-hr values, from temperate climate experience.
** High value due to long-term consolidation of sludge on lagoon bottom!
Data from partial-mix aerated lagoons in Alaska.
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9-30
sludge wasting from exposed extended aeration plants will be required
about twice as frequently as in more temperate climates.
Temperature inhibitions on digestion increase the rate of sludge
O
accumulation in all types of lagoons. Values of 0.25 to 0.40 mj/1000
people/d have been reported for sludge accumulation in cold climate
facultative lagoons. Sludge will also accumulate at a faster rate in
aerated lagoons and available data indicates that the assumption of 5% of
total lagoon volume for sludge (9.4.3.2) is conservative, so that
cleaning and sludge removal might be required on a 10-15 year cycle.
The accumulation of undigested winter sludge imposes a high
oxygen demand on a lagoon when liquid temperatures warm up in the spring.
Supplemental surface aeration may be helpful for odour control during
this period.
Procedures for sludge digestion follow temperate zone practice.
It is necessary to provide additional heat and/or insulation to maintain
anaerobic digestion in cold climates. Burial of digester tanks is common
in the subarctic to provide natural insulation. Aerobic digestion is
less temperature-sensitive but produces a less stable product.
Dewatering of sludge prior to disposal also follows conventional
temperate zone practice. One exception is the use of natural freeze-thaw
cycles for dewatering. If sludge is flooded on exposed beds and allowed
to freeze, the solid particles will settle readily upon thawing.
Approximately 50% of the total volume can be decanted from the beds as
supernatant and returned to the treatment plant. The thickened sludge
can either be left on the beds for complete drying or disposed of
directly.
9.5 On-Site Treatment
These systems might directly serve a single dwelling or a
cluster of dwellings. Any system that does not depend on centralized
collection and treatment for an entire community falls in this eategory.
Discharging systems such as septic tank/soil adsorption combinations, or
low to no discharge units represented by a variety of toilet units and
recycle systems, are included.
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9-31
9.5.1 Systems with discharge
Septic tanks and similar units fall in this category. Basic
process design criteria are similar to those used in temperate zones.
Section 10 discusses special aspects of cold climate septic systems.
Small-scale aerobic units, usually based on the extended
aeration process, are available for individual dwellings or clusters of
dwellings. These are generally heated and housed so design is conven-
tional. If properly operated these units can, in theory, achieve secon-
dary quality effluent and could, if allowed by the applicable regulatory
agency, be designed for point discharge to surface waters. If properly
operated, the reduction in BOD and suspended solids achieved would permit
effluent disposal in a leach field smaller than that required for septic
tank effluents. In all cases, the critical aspect is proper operation,
plus a method for positive solids separation and solids disposal.
General experience has shown that neither the average homeowner or
similar personnel have the competence and dedication required to service
such units. They should only be considered if some permanent provision
can be made for management and maintenance of the units on a regular
basis by some outside authority.
Intermittent or seasonally occupied facilities are common in
cold regions. Several arrangements are available for small-seale opera-
tions either with or without discharge. In the former ease, a small
physical/chemical packaged plant ean be run intermittently and still give
satisfactory removal efficiencies. Operator skills, resupply and sludge
management ean be problems. For a small facility a two-eell, controlled-
diseharge pond, operating in parallel might be suitable. Residence time
prior to discharge would be a full year. If occupancy is only in the
warm summer months, an evapotranspiration bed preceded by a septic tank
or aerobic unit will provide a no-discharge system. Design would be the
same as for a temperate zone location, with inclusion of climatic data
specific to the site and consideration of permafrost under the bed.
9.5.2 Low or no discharge systems
These include pressure or vacuum toilets, vault toilets, and a
whole variety of toilet units for the individual home based on
electrical, mechanical or biological proeesses.
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9-32
Low water use toilets, as well as other conservation devices,
reduce the volume of liquid to be managed but not the mass of pollutants.
The same is true of separation of waste streams into "black" and "grey"
water. Both streams require comparable treatment even through the total
volume may be reduced. Although the volume of liquid may be less,
leaching fields or other soil adsorption systems receiving such wastes
should be conventionally designed and not otherwise reduced in size if
BOD loading is unchanged. Tank size for other forms of "packaged"
treatment for such wastes may be reduced but the energy and/or chemical
requirements will be higher because of higher concentrations of
pollutants.
Vault toilets are best suited for seasonal use, particularly in
the summer. They are most widely used at camps and recreational sites.
There can be problems in these cases because of indiscriminant dumping of
trash and garbage which increases the clean-out frequency. In any event,
periodic cleaning and disposal of vault wastes is required. Basic design
is similar to conventional practice.
Appendix B describes various types of household water
conservation alternatives, including toilet systems. Recirculating
chemical toilets are in common use in airplanes and travel trailers.
Capital costs are high ($100-$1000) and chemicals are expensive. The
mechanisms are complex, maintenance is required, and periodic disposal of
collected material is still necessary.
Variations include single-pass or reeyole toilets which use a
fluid other than water. Fuel oil has been tried on a single-pass basis
with the entire mixture then burned for heat. The fire hazard at the
toilet was considered significant. An alternative ia to mix the waste
from low water use toilets with fuel oil for burning in boilers. Either
approach requires complex equipment and skilled maintenance. Recycle
toilets based on mineral oil are available. The specific gravities are
sufficiently different that the oil and waste separate in a holding tank
and the oil is recycled. Disposal of the colleeted wastes is still required
and costs for a single unit may approach several thousand dollars.
Ineinerating toilets, whether based on oil, gas or electricity,
require considerable energy, are complex to maintain, and can be
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9-33
aesthetically objectionable, particularly where a temperature inversion
exists and vent stack emissions sink rather than rise.
Composting toilets are in wide use in Scandanavia for vacation
homes. A full-scale unit can receive all feces, urine, and kitchen
wastes from a household. Wash water and other liquids must be discharged
elsewhere. Successful operation requires a degree of commitment and
dedication not commonly found in the North American Arctic and subarctic.
The most common nonwater carriage system in use is the honey bag
toilet. Pickup, handling and disposal of the bags creates potential
health problems. Efficient systems of this type are in operation in
coastal communities in Greenland, where pickup and disposal is a reliable
municipal service. Section 13 discusses ultimate disposal.
9.6 Operation and Maintenance
Repeated studies of treatment systems in cold climates have
shown that performance does not achieve the design goals due to poor
operation and maintenance. Initial operator training is essential to
successful system performance. Another critical element in the design
process for wastewater treatment is the preparation of the operations and
maintenance manual. It is even more important in the arctic and
subarctic because of the remote locations, the general lack of skilled
personnel, and the relatively rapid turn-over of operators at both
military and civilian treatment systems. In the former case, a one-year
tour of duty is normal. This lack of continuity and experience results
in a situation where the operator's only routine source of guidance and
assistance is the manual. Minor details which may appear self-evident to
the designer/author may be critical to the operater/reader.
9.6.1 Contents of O&M manuals
The basic requirements for process operation and maintenance may
not differ from eonventional temperate zone practice but the cold regions
O&M manual should explain them in greater detail since it may be the only
information source. Special winter operational requirements must be
clearly defined. These may include draining lines, winterizing pumps,
activating heat tapes, etc. Equipment for emergency or future use must
be clearly identified. For example, a heat tape intended to thaw a pipe
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9-34
need not be continuously operated, and extra pumps and blowers may only
be for standby.
9.6.2 Design for O&M
Attention to detail during design of a system will help relieve
or avoid subsequent operational or maintenance problems. Many typical
examples, such as condensation and control panel locations, were
discussed previously in this chapter as they relate to a particular
process design. Other generally applicable items would include:
a) Alarm systems to indicate failure in the process (i.e.,
power failure, overflow, etc.) are essential, particularly
for small units that receive intermittent attention.
b) The air circulation and heat distribution in an enclosing
structure must be carefully planned. Often the temperature
at the floor level and in "blind" spots can be below
freezing, resulting in freezing of pipes and appurtenances.
c) The depth and location of winter ice and snow cover must be
considered to ensure easy access to all critical components.
d) Pumps and other intermittently used facilities must either
be protected or winterized each year.
e) Coordination must be established with other critical
elements in the community or camp to avoid unexpected or
adverse effects on the system. Dumps or spills of toxic
materials must be controlled. An improperly maintained or
located grease trap could freeze or impose excessive organic
loads on a system.
f) Some remote systems may be subject to power failures and
voltage variations. Provisions should be made to protect
electrical equipment from burning out due to low voltage.
9.7 Costs
There are no simple rules of thumb for estimating costs of cold
regions waste treatment systems because of the limited data base, the
extreme variability of logistical problems, and high labour rates. Most
temperate zone cost data do not include the small-scale systems commonly
required in the Arctic. The selection of appropriate indices and trend
-------
9-35
factors can also be a problem; extrapolation from temperate zone values
is not recommended except for large communities. Two sources of cost
data for waste treatment in Alaska were available. The first compares
construction costs for facilities at the Alaska pipeline camps and is
summarized on Table 9-9. The other is from a series of partial-mix
aerated lagoons constructed by the U.S. Army Corps of Engineers, Alaska
District, in 1972 at various locations in Alaska. These data are
summarized on Tables 9-12 through 9-15.
Anchorage, Ak, was adopted as the base and the individual costs
from remote sites were used to generate the relative cost factors shown
on Table 9-13. This gives an approximation of the variation in costs due
to location.
Construction costs for a large (3800 m^/d) partial-mix
aerated lagoon near Fairbanks, Ak, are summarized in Table 9-14.
Estimated O&M costs for smaller lagoons are given in Table 9-15.
TABLE 9-12. CONSTRUCTION COSTS - PARTIAL-MIX AERATED LAGOONS (1972 $)
All single-cell, membrane-lined, including control building with blowers
and erosion chlorinators. Size range: 10 000 - 14 000 gpd (38-53
nr/d) • Cost values are the average of six installations* and are
expressed in dollars per 1000 gal (3.785 m3) of average daily flow.
Lagoon
Materials and equipment $3 400
Labour 2 900
$6 300
Control Building
Materials and equipment $1 600
Labour 1 100
$2 700
Actual Construction 9 000
Mobilization and Demobilization (15%) 1 400
Design, Inspection, Misc. (13%) 1 200
Total Cost $11 600
* Locations: Tin City, Cape Lisburn, Tatalina, Indian
Romanzof, Cape Newenham (Alaska).
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9-36
TABLE 9-13. RELATIVE COST FACTORS - PARTIAL-MIX AERATED LAGOONS (1972 $)
All single-cell, membrane-lined, including control building with blowers
and chlorination. Size range: 10 000 - 30 000 gpd (38-114 m3/d).
Based on total costs including all construction, mobilization demobilization,
design and inspection. Costs expressed as an index relative to Anchorage.
Location Cost Factor
Anchorage 1
Cape Romanzof 3.3
Cape Newenham 3.6
Indian Mountain 4
Cape Lisburne 4.3
Tin City 4.6
TABLE 9-14. CONSTRUCTION COSTS - EIELSON AFB AERATED LAGOON (1972 $)
o
A 3800 mj/d, two-eel! lagoon, lined with butyl rubber membrane.
Helical aeration diffusers, 28 m control building with blowers,
and a chlorine contact chamber.
Lagoon
Materials and Equipment $280 000
Labour 108 OOP
$388 000
Control Building
Materials and Equipment 81 000
Labour 47 OOP
$128 OOP
Actual Construction $516 PPP
Mobilization and Demobilization (9%) 46 000
Design, Inspection, Misc. (13%) 73 OOP
Total Cost $635 OOP
Cost by engineering discipline:
Civil Engineering 45%
Mechanical Engineering 50%
Electrical Engineering 5%
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9-37
TABLE 9-15.
ESTIMATED ANNUAL OPERATION AND MAINTENANCE COSTS
PARTIAL-MIX AERATED LAGOONS IN ALASKA (1972 $)
Labour
Materials
Elendorf AFB
11 m3/d
sigle-cell
Widwood, AFS
60m3/d
tw-oell
Kig Salmon AFB
30m3/d
sigle-eell
$4 000
$2 200
$7 300
$1 000
$1 000
$4 000
The influence of remote location is apparent when the values for
Elmendorf AFB, in Anchorage, are compared to those for King Salmon AFB,
which is on the Alaska Peninsula.
9.8 References
1. Bailey, J.R. et al, A study of flow reduction and treatment of
wastewaters from households. U.S. Federal Water Pollution
Control Administration, Contract Report 14-12-428, 1969.
2. Witt, M.D. et al, Rural household waste eharaeterization.
Proceedings of the National Home Sewage Disposal Symposium, ASAE
pubs., Proo. 175, 1974.
3. Jespersen, F., The vacuum sewage system. Utilities Delivery in
Arctic Regions. D.W. Smith (ed.), Environment Canada Rpt. EPS
3-WP-77-1, pp. 364-387, Ottawa, 1977.
4. Given, P.W. and H.G. Chambers, Workeamp sewage disposal. Some
problems of solid and liquid waste disposal in the northern
environment, Environment Canada Rpt. EPS-4-NW-76-2, pp. 1-42,
Edmonton, 1976.
5. Flaek, J.E., Design of water and wastewater systems for rapid growth
areas. Environmental Resources Center, Colorado State University
Press, 149 pp, 1976.
6. Snoeyink, V.L. et al. USAF Mobility Program Wastewater Treatment
System, U.S. Air Force Teeh. Rpt. AFWL-TR-71-169, 60 pp, 1972.
7. U.S. Environmental Protection Agency, Process design manual for
wastewater treatment faeilities in sewered small communities,
EPA-625/1-77-009, 1977.
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9-38
9.9 Bibliography
Alter, A.J. Sewage and sewage disposal in cold regions. U.S.
Army, Cold Regions Research and Engineering Laboratory. Monograph
III-C5b, 106 pp, 1969.
Alter, A.J. Water supply and waste disposal concepts applicable in
permafrost regions. Proceedings of the 2nd International Permafrost
Conference, Yakutsk. North American Contribution. Academy of
Sciences, National Research Council, pp. 557-581, 1973.
Alter, A.J. The polar palace. The Northern Engineer, University of
Alaska, 5:2, 4-10, 1973.
Antonie, R.L. Rotating biological contactors for secondary waste-
water treatment. Lake Tahoe Wastewater Treatment Seminar Manual,
1976.
Benjes, H.H., Small community wastewater treatment facilities -
biological treatment systems. Design Seminar Handout, Small
Wastewater Treatment Facilities, U.S. Environmental Protection
Agency, Cincinnati, Ohio 1978.
Buens, G.E., Evaluation of aerated lagoons in a cold climate.
Proceedings 22nd meeting Western Canada Water and Sewage Conference,
pp. 21-40, 1970.
Christiansen, C., Cold climate aerated lagoons. Proceedings 2nd
Int. Symp. on Cold Regions Engineering. J. Bwolich and P. Johnson
(ed.), University of Alaska, Fairbanks, pp. 318-351, 1977.
Clark, S.E. et al, Biological waste treatment in the far north.
U.S. Environmental Protection Agency (FWQA), Project Report 1610, 36
pp, 1970.
Clark, S. et al, Alaskan industry experience in arctic sewage
treatment. Working paper No. 13 at 26th Purdue Industrial Waste
Conf., Purdue Univ, Lafayette, Indiana, 1971.
Clark, S., Coutts, H., and Christiansen, C., Design considerations
for extended aeration in Alaska. Murphy, R. and Nyquist, D. (ed.),
Water Pollution Control in Cold Climates, U.S. Environmental
Protection Agency, Water Pollution Control Research Series 16100 EXH
11/71. pp. 213-236, 1971.
Clark, S.E. et al, Alaska Sewage Lagoons. 2nd Intl. Symp. on Waste
Treatment Lagoons, U.S. Federal Water Quality Administration,
Washington, B.C., pp. 221-230, 1970.
Coutts, H., Arctic Evaluation of a small physical-chemical sewage
treatment plant. U.S. Environmental Protection Agency, Arctic
Environmental Research Lab., Fairbanks, Alaska, 1972.
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9-39
Eckenfelder, W.W. and A.J. England, Temperature effects on
biological waste treatment processes. Symposium on Water Pollution
Control in Cold Climates, R.S. Murphy and 0. Nyquist (ed.),
University of Alaska, Fairbanks, pp. 180-190, 1970.
Gordon, R. and Davenport, C., Bateh disinfection of treated
wastewater with chlorine at less than 1°C. U.S. Environmental
Protection Agency, Washington, B.C., EPA-660/2-73-005, 1973.
Grainge, J.W. et al, Management of waste from arotie and subarctic
work camps, report for Task Force on Northern Oil Development.
Report 73-19, Information Canada Cat. No. R72-10173, 153 pp, 1973.
Grainge, J., Impact of community planning on quality of life in the
north. Proceedings of Third National Hydrotechnical Conference,
Quebec, pp. 483-500, 1977.
Grainge, J.W., Shaw, J.Q. and Slupsky, J.W., Report on Toilet Units.
Public Health Engineering Div., Dept. of Environment, Edmonton,
Alberta. Manuscript Report NR-71-2. 21 pp, 1971.
Grube, G. and Murphy R., Oxidation ditch works well in subarctic
climate. Water and Sewage Works, Vol. 116, No. 7, pp. 267-271,
1969.
Heinke, G.W. and D. Prasad, Disposal of concentrated wastes in
northern areas, Environment Canada Report EPS 4-NW-76-2, pp.
87-140, Edmonton, 1976.
Rickey, J. and Duncan, D., Performance of single family septic tank
system in Alaska. JWPCF 38: 1298-1309, 1966.
LeGros, P.G., and N.L. Drobny, Viruses in polar sanitation - a
literature review. U.S. Navy, Civil Engr. Lab. Tech Rpt. R-505, 15
pp, 1966.
Lin, K.C. and G.W. Heinke. Plant data analysis of temperature
significance in the activated sludge process. JWPCF, 49(2):286-295.
Metcalf and Eddy Inc. Wastewater Engineering: Treatment, Disposal,
Reuse. McGraw-Hill Book Co., New York, 920 pp, 1979.
Middlebrooks, E.J., C.D. Perman and I.S. Dunn, Wastewater stabiliza-
tion lagoon linings, U.S. Army Cold Regions Research and Engineering
Laboratory, Special Report, in press, 70 pp, 1978.
Morrison, S.M. et al, Lime disinfection of sewage bacteria at low
temperature. U.S. Environmental Protection Agency. EPA 660/2-73-
017, Washington, D.C., 90 pp., 1973.
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9-40
Murphy, R. and Ranganathan, K., Bio-processes of the oxidation ditch
in a sub-arctie climate. IN: Davis, E. (ed) , International
Symposium on Wastewater Treatment in Cold Climates, Environment
Canada Report EPS 3-WP-74-3, Ottawa, 1974.
Murphy, R.S., et al, Water supply and wastewater treatment at
alaskan construction camps. U.S. Army Cold Regions Research and
Engineering Laboratyr, Report in press, 1978.
Orr, R.C. and D.W. Smith. A review of self-contained toilet systems
with emphasis on recent developments. Utilities Delivery in Arctic
Regions. D.W. Smith (ed.). Environment Canada Rpt. EPS 3-WP-77-1,
pp. 266-308, Ottawa, 1977.
Otis, R.J., et al. On-site disposal of small wastewater flows.
U.S. Environmental Protection Agency, Washington, D.C.,
EPA-625/4-77-011, 1977.
Puchtler, B., Reid, B., and Christiansen C., Water-related utilities
for small communities in rural Alaska. U.S. Environmental Protec-
tion Agency, Washington, D.C., EPA-600/3-76-104, 1976.
Reed, S.C. and R. S. Murphy, Low temperature activated sludge
settling. Journal S.E.D. ASCE, SA4, 747-767, 1969.
Reed, S.C., Alternatives for upgrading USAF wastewater lagoons in
alaska. U.S. Army Cold Regions Research and Engineering Laboratory,
Hanover, New Hampshire, 94 pp., 1976.
Reed, S.C. et al, Land treatment of wastewater for Alaska.
Proceedings Second International Symposium on Cold Regions
Engineering, J. Bordiek and P. Johnson (ed.), Univ. of Alaska,
Fairbanks, pp. 316-318, 1977.
Reid, B.H., Some technical aspects of the Alaska village
demonstration project. IN: Utilities Delivery in Arctic Regions,
Enviro-nment Canada Rpt. EPS 3-WP-77-1, pp. 391-438, Ottawa,1977.
Reid, L.C. Jr., Design and operation of aerated lagoons for the
arctic and subarctic. Presented at the U.S. EPA Technology Transfer
Design Seminar, Anchorage, Ak., April 9-10, 1975, 29 pp, 1975.
Ryan, W., Design and construction of practical sanitation facilities
for small Alaskan villages. Permafrost. Proa, of the 2nd
International Conference, Yakutsk. North American Contribution.
National Academy of Sciences, National Research Council, pp.
721-730, 1973.
Sletten, R.S., Land application of wastewater in permafrost areas.
3rd International Permafrost Conference, National Academy of
Science, Washington, D.C., 1978.
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9-41
Smith, D.W. and P.W. Given, Evaluation of northern extended aeration
sewage treatment plants. Proceedings 2nd International Symposium on
Cold Regions Engineering, J. Burdick and P. Johnson (ed.)> Univ. of
Alaska, Fairbanks, pp. 291-316, 1977.
Tilsworth, T. et al. Freeze conditioning of waste activated sludge.
Proceedings 27th Industrial Waste Conference. Purdue University,
486-491, 1972.
U.S. Army. Domestic wastewater treatment TM 5-814-3, in press.
U.S. Army Corps of Engineers, Wash. D.C., 1978.
U.S. Environmental Protection Agency, Process design manual for land
treatment of municipal wastewater, EPA 625/1-77-008, Washington,
D.C., 1977.
U.S. Navy. Design Manual, Cold Regions Engineering, NAVFAC DM-9.
Dept. of Navy, Naval Facilities Engineering Command. Alexandria,
Va., 1975.
-------
SECTION 10
WASTEWATER DISPOSAL
Index
Page
10 WASTEWATER DISPOSAL 10-1
10.1 Discharge Standards 10-1
10.1.1 Environmental conditions 10-1
10.1.2 Standards 10-3
10.1.3 Microbiological considerations 10-4
10.2 Subsurface Land Disposal 10-4
10.2.1 Septic systems 10-5
10.2.2 Mechanical systems 10-9
10.2.3 Seepage pits 10-9
10.3 Outfalls 10-9
10.3.1 Receiving water 10-10
10.3.2 Types of outfalls 10-11
10.4 Intermittment Discharge 10-12
10.4.1 Thermal considerations 10-12
10.4.2 Seasonal discharge 10-14
10.5 Land Disposal 10-15
10.5.1 Soil conditions 10-15
10.5.2 Annual cycle 10-15
10.5.3 Loading rates 10-15
10.6 Swamp Discharge 10-16
10.6.1 Area affected 10-16
10.6.2 Management 10-18
10.6.3 Effects 10-18
10.7 Sludge Disposal 10-18
10.7.1 Sludge drying/freezing 10-19
10.7.2 Sludge pits 10-19
10.7.3 Lagoon sludge disposal 10-20
10.7.4 Landfill 10-20
10.8 References 10-20
-------
List of Figures
Figure
10-1
10-2
10-3
10-4
10-5
Soil Profiles
Insulation in Soil Adsorption Fields
Maximum Ice Thiekness Observations, 1969-70
Example of an Ocean Outfall Design
Lagoon Weir Design
Page
10-6
10-8
10-10
10-12
10-13
10-2
10-3
LIST OF TABLES
Winter Dissolved Oxygen Concentrations in Selected
Streams
Efficiency of Septic Tanks
Results of Spray Application of Lagoon Effluent at
Eielson Air Force Base (15 em lysimeters)
Page
10-2
10-5
10-17
-------
10-1
10 WASTEWATER DISPOSAL
10.1 Discharge Standards
A total water management program requires the return of the
water to the environment. The treatment requirements in northern loca-
tions must normally be based on winter receiving water characteristics,
which include critically low flows and dissolved oxygen levels. Two
general approaches used to control man-created wastewaters are:
1) basic effluent standards, and
2) specific stream standards.
Most North American locations make use of a combination of the
two types of standards. The important aspects of the two approaches to
water management are presented below. Details of subsurface disposal,
outfalls, intermittent discharges, land disposal, swamp discharge and
sludge disposal follow the discussion of standards.
10.1.1 Environmental conditions
Present knowledge of how arctic and subarctic river, lake and
estuary systems respond to wastewater discharges is limited. Some basic
information on the physical and chemical conditions, and the ecology of
streams and rivers has been gathered. The annual cycles in subarctic
lakes are just now becoming subjects of more interest and study [1,2].
Not only is information on how aquatic systems function limited, but the
situation is compounded by extremely varied conditions throughout the
North.
The environmental conditions within northern rivers and lakes
vary considerably with time of year and location. Winter flow in many
rivers is negligible, while summer flows may be high and carry heavy
sediment loads. Ice cover is the rule, rather than the exception, with
water temperatures at 0°C in the winter, and generally low during the
remainder of the year. During periods of iee cover, the concentration of
dissolved oxygen (DO) progressively reduces. Near the mouths of most
major rivers in Alaska, natural winter DO levels are well below generally
recommended minimums, as shown in Table 10-1 [3], The organisms present
have adapted to these harsh conditions through such methods as reduced
metabolic rates and migration. However, tolerance levels have not been
well defined.
-------
10-2
TABLE 10.1 WINTER DISSOLVED OXYGEN CONCENTRATIONS IN SELECTED STREAMS
Stream/Location
Yukon River
near Eagle, Ak (1664 km upstream)
near Alakanuk, Ak
Tanana River
near Fairbanks
at Yukon River
near Fairbanks
at Yukon River
Colville River
at Umiat
Kuparuk
Dissolved
Oxygen
mg/L
10.5
1.9
9.9
5.7
10.8
6.5
7.5
8.4
8.4
Date of
% saturation Sample
73
13
69
40
75
46
52
58
58
Mar. 1971
23 Feb. 1970
5 Mar. 1970
Mar. 1969
Mar. 1969
Feb. 1971
Based on Reference [3],
Few studies of the effects of wastewater discharges on these
waters have been conducted. Gordon [4] showed in laboratory experiments
that indigenous bacteria exerted an oxygen demand at low temperatures,
and the addition of organic and inorganic nutrients increased the rate of
oxygen utilization. Murray and Murphy [5] also studied the biodegrada-
tion of organic substrates at low temperatures. They found that the
food-to-microorgandsms (F/M) ratio was more important than temperature in
determining the rate of DO depletion.
In another study, the effect of ice cover on the DO content of
the Red Deer River in Alberta was measured [6], In this river, which
receives municipal effluent, the initial five-day, 20°C biochemical
oxygen demand (BOD) of the river below the outfall and the rate constants
established by BOD bottle tests were found to bear little relation to
oxygen uptake in the ice-covered, shallow river. Total organic carbon
(TOC) was closely related to oxygen depletion. It was concluded that
biological oxidation under river ice was a complex reaction and the bottom
characteristics and benthic demand were very important. The bottom of
-------
10-3
Red Deer River is mainly gravel and rock, allowing a large surface area
for the growth of microorganisms.
In evaluating the effect of wastewater discharges from construc-
tion camps, Greenwood and Murphy [7] estimated that a 300-man camp
located near the mouth of the Colville River, Alaska, could store
wastewater for nine months, discharge it during a one-month period in
June, and increase the stream BOD by only 0.0026 mg/L with proper
dilution. This approach, the use of dilution, is a very real alternative
which warrants careful consideration.
The results of many of the studies and evaluations differ but
are not necessarily contradictory, because each study was conducted under
different conditions. There are many gaps in the knowledge of aquatic
kinetics yet to be filled before the assimilative capabilities of a
northern receiving water can be accurately assessed or predicted.
Assimilative capacities of northern rivers in the winter are
undoubtably lower, and perhaps much lower, than rivers of similar
physical characteristics located in temperate zones. Considering the
complexity of the ecosystem, the great range of physical characteristics,
and the impossibility of comparing these rivers to those in areas where
much more research and experience has been documented, it will be quite
some time before northern water systems can be accurately modelled.
Oxygen utilization rates and reaeration coefficients at temperatures near
0°C need further development. In the interim, the aquatic integrity
must be protected by knowledgeable utilization of the limited data
coupled with common sense.
10.1.2 Standards
Standards to protect the ecological, aesthetic and sanitary
integrity of receiving waters ean be divided into three types [8]:
1) standards based solely on receiving water quality,
2) standards based on the quality of the effluent discharge,
3) standards which combine both of the above.
Physical, ecologieal, and assimilative capacity characteristics
of receiving waters vary considerably, as do land use and population
density. These variations, together with the economic limitations and
-------
10-4
social structure, make standards based on a combination of receiving
water quality and effluent discharges appear the most reasonable.
The interim guidelines for wastewater treatment for the Yukon
and Northwest Territories were established on a community-by-community
basis [12], Decisions on treatment recommendations were based on
comprehensive studies of expert opinion on public health and environ-
mental needs. Of course, they are subject to modification as community
conditions or environmental requirements change or as more information
becomes available. Exact treatment techniques were not specified;
rather, general effluent quality objectives were established. This
appears to be a sound approach to meeting the environmental quality needs
of the North.
Presently, the State of Alaska and the U.S. Environmental
Protection Agency require mandatory secondary treatment, with further
treatment of the wastewater required if it is to be discharged to
sensitive receiving waters. These standards were established on a
nationwide basis. Contact should be made with the appropriate
territorial water board, provincial government agency, federal government
agency or, in Alaska, the Department of Environmental Conservation, to
establish the required quality for discharge to available receiving
waters.
10.1.3 Microbiological considerations
The survival of pollution indicator microorganisms has been
shown to be longer in cold water than in warm. Gordon [9], Davenport et
al [10] and Bell et^ ja_l [11] have pres.ented detailed information on the
extended survival of these organisms in northern rivers. This informa-
tion identifies the need for careful consideration of disinfection to
ensure that water uses are not seriously affected.
10.2 Subsurface Land Disposal
Several methods of wastewater disposal into soil are or have
been practiced, including absorption field disposal of septic tank or
aerobic treatment effluents, direct burial in pits, disposal in ice
crypts or snow sumps, and dumping and covering in a landfill.
-------
10-5
10.2.1 Septic systems
Septic systems can be used in some arctic and subarctic
locations. The presence of, and depth and thickness of permafrost, the
type of soil and its percolation rates, and the frost penetration depth
will influence the use of septic systems. General septic system design
information is available from several sources, such as the "Manual of
Septic Tank Practice" [13], and the "Private Sewage Disposal Systems
Instructions to Installers, 1978" [14].
The basic functions of septic tanks are: a) removal of
settleable and flotable solids, b) sludge and scour storage, e) some
anaerobic biological treatment, and d) to condition liquids for ground
adsorption (hydrolyze solids).
Some efficiency information for septic tanks used in cold climate
regions are presented in Table 10-2.
TABLE 10-2. EFFICIENCY OF SEPTIC TANKS
Percent Removal
Conditions BOD SS Total Solids References
Average of 10 Air Force Base sites 33 42 22 [15]
in Alaska
Tanks in heated houses 46 64 48 [15]
Tanks - steam heated 40 31 34 [15]
Tanks - unheated 14 38 30 [15]
Field study at College, Alaska,
2.5-day detention time 28 43 - [16]
Lab study, U.S. PHS, temperature
4-10°C, 2-day detention time 49-52 83-89 31-41 [17,18]
Lab study, University of Washington,
temperature 4.4 and 15°C, 4.5-day
detention time 49-52 83-86 31 [17,18]
Normal primary sedimentation 20-40 45-70 [17,18]
The sizing of the system should follow procedures in the
"Manual of Septic Tanks Practice" [13].
-------
10-6
10.2.1.1 Soil conditions. The most critical aspect of arctic and sub-
arctic septic systems design is the soil condition. Figure 10-1 shows
examples of soil profiles found in subarctic areas of Alaska. The type
of soil will influence the frost penetration depth. Its location with
respect to surface and groundwater will also influence frost penetration
and frost heave. In locations where permafrost is deep it may be possi-
ble to install an absorption field. However, groundwater (suprapermafrost
water) movement patterns should be investigated, along with potential
groundwater supply locations. Percolated water from the absorption field
may move down to the frozen soils and then tend to move horizontally.
Depending upon the total temperature regime, the wastewater may cause
additional thaw of the permafrost.
Thermal protection for the tank and adsorption field should be
designed for the worst winter conditions, minimum or no snow, and low
Boring number
Date drilled
Water tables
After boring
While drilling
Frozen ground
Sample location
Typical Boring Log
Elev. 108m
•0
•0.5m
Organic material
Consid Visible Ice ICE + ML
106-SJ It estimate 65% Visible Ice
1)280, 56.2%, 1200 kg./m3, ML
• 2.0m
Sandy silt
Little to No Visible Ice 4.3-10.0m 0-2 Om Vx •
220,57.1%, 1300 kg./m3,-2°, GP,
Sandy gravel
•8.0m
300
Schist
•10.0m
Elevation
Strata change
Approximate strata change
Ice, description and classification
(Corps of Engineers method)
Unified or FFA classification
Temperature °C
Dry density
Water content
Blows/m
Sample number
Drill depth
Generalized soil or rock description
FIGURE 10-1. SOIL PROFILES
-------
10-7
temperatures. Freezing prevention should be designed into the system.
Year-round operation will require continuous heat additions in the form
of warm wastewater or external heating inputs. Methods of preventing
freezing which have been used include:
1) housing the septic tank in a warm structure above or below
ground;
2) placing a steam line along pipes or around septic tank;
3) placing an electric heat tape along pipes or around septie
tank;
4) applying insulation around septic tank and over top of pipes
(foam, sheets, snow cover, earth cover, etc);
5) use of warm water to increase the heat input of wastewater.
In locations where the need for wastewater disposal is seasonal,
such as in recreational areas, the tank may be pumped out after the
recreational activities have ceased. A minimum of one week between the
cessation of flow and pumping should be allowed. When the facilities
remain in operation year-round, but at a reduced flow during the winter
months, more than one system may be used in parallel to allow part of the
unit to be shut down and pumped.
10.2.1.2 Absorption field design. The soil absorption system serves as
an additional sewage treatment unit. This component is a subsurface
distribution system which delivers the settled sewage flowing from a
septie tank to the soil found suitable for ultimate disposal. A soil
absorption system may be one of three different types: absorption
trenches, mound seepage beds, and seepage pits. The absorption trench
system provides the advantage of discharging the settled sewage near the
surface of the ground and over a wide area. The seepage pit, in
comparison, discharges into deeper soil strata at concentrated points.
Heat loss control is the key consideration in eold climate
systems. Figure 10-2 shows how insulation can be used to reduce heat
loss during winter periods. It should be noted that the freezing front
will move down between trenches and may cause the formation of a finite
thawed area.
-------
10-8
Top view
o °- }:.'
100 mm Polystyrene 'VTv °-V <>--0-
'
lank
i
1
1
•
1 [
I 1
...
:
1 "
L.-..J
1 1
i
i r
i 1
i i
n n 1000 Drain
Detail
Minimum 2 m
J_
•0-::-f*-j- Native backfill
'b •
Drain lateral
Screened gravel
1 00 mm Polystyrene
1 00 mm Drain manifold (header)
Building
Septic tank
See detail
FIGURE 10-2. INSULATION IN SOIL ABSORPTION FIELDS
10.2.1.3 Dosing tank techniques. When the quantity of sewage exceeds the
amount that can be discharged in approximately 150 linear metres of absorp-
tion field tile, a dosing tank should be used. Suah a tank allows proper
distribution of wastewater to different parts of the field. This technique
also allows the absorption field a period of time to percolate the water.
In cold climates a small continuous discharge may freeze due to
rapid heat loss to the soil. In this case., a dosing tank allows a larger
volume and a greater amount of heat to be discharged at one time. This
provides for greater penetration of the absorption field. In some locations
it may be desirable to pump the effluent to a suitable absorption area.
The dosing tank should be equipped with an automatic siphon whieh
discharges the tank once every three or four hours. The tank should have
a capacity equal to about 60 to 75 percent of the interior capacity of
the tile to be dosed at one time. (See Section 7.)
10.2.1.4 Clean-out requirements. Due to the normally low temperatures
during all or part of the year, sludge digestion and hydrolization rates
-------
10-9
will be low and sludge accumulation higher than in temperate climates.
This condition results in a more frequent need to remove sludge from the
tank. Sludge removal frequency should be every 12 to 24 months in Alaska
and northern Canada.
10.2.2 Mechanical systems
Several mechanical treatment systems are available for small and
moderate quantities of wastewater. These are discussed in Section 9.
Subsurface disposal of effluent from such plants requires special
consideration.
10.2.2.1 Soil conditions. The most critical aspect of aerobic effluent
disposal is the solids loading. Aerobic systems frequently have excessive
suspended solids concentrations in the effluent. These systems should,
therefore, include positive solids separation.
10.2.2.2 Absorption field design. As with septic systems the key
consideration must be freeze prevention. With a properly designed solids
separation system clogging of the field will be minimized.
10.2.2.3 Sludge disposal. To prevent clogging of the absorption field,
sludge must be removed frequently from systems in use in cold regions.
Disposal practices are discussed in a later section.
10.2.3 Seepage pits
Deep pits are used in some areas for the disposal of wastewater.
Normally, the area required is fairly large and, therefore, use is
limited to a small number of dwellings. The major concerns are proper
freeze protection and prevention of nitrate and bacterial contamination
of the groundwater. They are generally much easier to protect from
freezing than an absorption field, and much less excavation is usually
required.
10.3 Outfalls
Outfalls to surface water are the most common wastewater discharge
technique. Design and operation of the discharge systems requires under-
standing of the receiving water quality and quality of the discharge. It
may be necessary to operate the discharge on an intermittent or seasonal
basis. It is advisable to design the outfall pipe so that is does not
-------
10-10
pass through a water-air interface. This will prevent damage during
periods of ice cover.
10.3.1 Receiving water
The type of receiving water bodies and the effluent standards
which pertain are important factors in the type of outfall structure
designed.
10.3.1.1 Ponds and lakes. Ponds are generally shallow, with depths up
o
to two metres. Surface areas range from a few 100 to a few 1000 m , and
retention times are often extremely long, one to six months. Freeze depths
may vary from 0.5 to 1.5 m. Figure 10-3 shows ice thicknesses reported
for different locations. Ice thickness can be estimated mathematically
by assuming worst conditions of no snow cover and minimum heat input.
The use of a pond to receive treated wastewater would
effectively convert it to a polishing lagoon. Fencing and posting to
that effect is required. Local regulatory agencies should be consulted
before this approach is adopted.
FIGURE 10-3. MAXIMUM ICE THICKNESS OBSERVATIONS, 1969-70
(Values in cm )
-------
10-11
Lakes may have the ability to absorb a greater volume of
wastewater; however, regional regulations must be reviewed. Important
considerations include surface area, depth, volume-inflow relationships,
nutrients, flora and fauna, and benthic populations. Effluent quality,
especially with regard to microorganisms, must be high if there is a
potential for fishery or recreational use of the lake.
10.3.1.2 Streams and rivers. Northern streams and rivers are the most
common receiving waters for wastewater. Flow, iee depth and movement are
the most important factors to be considered. Dissolved oxygen conditions
through the winter and downstream uses are of particular importance in
selection of the type of outfall structure to be used.
10.3.1.3 Oceans. Where possible, ocean discharge is desirable.
Normally, the ability to absorb quality variations is very great. If
initial dispersion by outfall design and tidal movement is not obtained,
however, wastewater will concentrate on the surface, because fresh water
and sewage are less dense than salt water. The result is a visible
slick. The major advantage of sea disposal is dilution.
The design of the outfall must consider ice movement due to
tidal action, currents, near-by rivers and wind action. Figure 10-4
shows the general design of an ocean outfall for the north eoast.
10.3.2 Types of outfalls
Three basic types of outfalls exist: free fall from a pipe,
submerged diffusers, and weir structures.
10.3.2.1 Freefall. Freefall structures utilize an insulated pipe to
transport treated wastewater from the treatment facility to the discharge
point. Provisions must be made for freeze prevention. Cold air penetra-
tion into the end of the pipe could create ice blockage of the line.
10.3.2.2 Submerged pipe. Unique factors of concern in the design of
submerged outfalls are the problems associated with ice scour, and freeze
and iee damage protection of any portion of pipe crossing the air and
water interface.
10.3.2.3 Weirs. Weirs develop a number of problems if not properly
designed. During winter operation the unfrozen effluent must move to the
-------
10-12
Insulated electric heat
traced outfall pipe
Wastewater
discharge
Break-away couplings so that ice
movement may destroy pile
without interruption of service
Draft control over end of pipe
Pile supports
FIGURE 10-4. EXAMPLE OF AN OCEAN OUTFALL DESIGN
surface where cooling will occur. The effluent is then discharged to the
surface of a stream or channel. Serious icing problems can result.
Figure 10-5 shows a design which has been used successfully.
10.4 Intermittment Discharge
Winter dissolved oxygen conditions in many streams will preclude
wastewater discharge. In other locations, the volume of effluent may be
so small as to require slug discharge to prevent freezing.
10.4.1 Thermal considerations
Due to the location or type of discharge system used, heat loss
may be so great and the volume so small, that the effluent will freeze
before or right at the end of the discharge line. The potential for
freezing can be determined through the procedures given in Section 15.
Such problems are most common when freefall systems are used. To
eliminate this condition treated effluent should be stored in a manner
that will prevent freezing, and discharged when sufficient volume has
accumulated that complete expulsion from the discharge line is ensured.
-------
Valve box and valve stem extension
Frost heave protection |Ce cover.
r-~~-~ 1.5m minimum
Gate valve -
Gravity outfall
Upturned elbow
Anchor block
Maximum frost penetration
Insulated, electric heat traced pipe
2-3
Frost heave protection if required
»— Insulated cover
Gate valve
Concrete pad or rip-rap
-•- 40mm
Calking as required
Adjustable stop logs
Detail
L—
o
I
FIGURE 10-5. LAGOON WEIR DESIGN
-------
10-14
The discharge mechanism could be a syphon or pump, but must ensure that a
trickle discharge does not occur.
10.4.2 Seasonal discharge
Discharge of wastewater at times of maximum or substantial
stream flow is highly desirable because this eliminates the addition of
oxygen demanding materials to receiving water during the winter period.
The timing of this type of discharge will vary with the location.
10.4.2.1 Flow management lagoons. Flow management lagoons are used to
control discharge of organios or nutrients to streams or lakes during
periods of concern. Such systems were used at Trans-Alaska Pipeline camps
to hold wastewater for extended periods through the year. The holding
lagoons were pumped out during open water periods. Discharge to the
lagoons was through French drains.
10.4.2.2 Polishing lagoons. Discharge of treatment facility effluent
to a polishing lagoon may be necessary where the only available receiving
water is sensitive to nutrient additions. Polishing lagoons provide
additional BOD removal and phosphorus removal by chemical coagulation
during ice-free periods. Conventional or pumped discharge can be used.
10.4.2.3 Total retention. Total retention lagoons rely on percolation
and evaporation to dispose of the accumulated water. Percolation can be
provided by proper selection of the location of the lagoon. Gravel and
sand gravel areas can be formed in some northern areas. The lagoon
should be sized to hold an entire winter's wastewater flow (approximately
250 days). This allows for a particularly severe winter during which the
percolation route is sealed off by freezing. Discharge facilities also
should be included.
The water source of the community should be monitored for
contamination if groundwater is used. The peraolate and groundwater flow
patterns should be studied to ensure that health problems will not oceur.
Net evaporation can be estimated only roughly from wet and dry
bulb data and precipitation records. Normally, evaporation is estimated
on the basis of evaporation pan tests and corresponding coefficients;
however, very little data is available in the North. Care must be taken
in the design to discourage abnormal snow accumulation.
-------
10-15
10.5 Land Disposal
Land application of wastewater requires maintenance of the soil
permeability. In some cold climate areas this may be possible through
special design. However, many areas are unsuitable. The presence of
permafrost will limit vertical movement of the wastewater, and winter
freezeback of the active layer may prevent horizontal movement. It may
be possible to design a suitable system in areas where thawed zones
extend to a water body which does not completely freeze.
Another approach warranting consideration is the use of a
retention-land disposal system, making use of land disposal during the
warmer parts of the year and retention through the winter.
In general, land disposal is similar and subject to the same
constraints as land treatment. The major difference is that land
disposal systems are mainly concerned with getting the effluent into the
ground and away from the site. The major concern is that the effluent
moves in an acceptable direction and does not present a hazard to public
health.
10.5.1 Soil conditions
Arctic areas underlain with permafrost generally will be limited
to non-infiltration land disposal techniques. Overland flow techniques
may be suitable; however, little or no control studies have been
conducted. Essential considerations include winter storage requirements.
Suitable areas can be located for infiltration approaches in
areas of disoontinous permafrost. Again the winter storage requirements
are paramount. Design details are available in the U.S. Environmental
Protection Agency's "Technology Transfer Design Manual of Land Disposal" [22],
10.5.2 Annual cycle
Annual cycles involve the management of wastewater in conjunction
with winter and summer conditions. Complex installations may allow land
disposal of effluent during the summer and fall, discharge during early
winter, and ice mounding in late winter.
10.5.3 Loading rates
As with absorption fields, the allowable application rate is a
function of the soil hydraulic capacity. Methods for estimating
application rates are given in the "Design Manual of Land Disposal" [22].
-------
10-16
The effects of untreated wastewater disposal in cleared areas
were studied in the Northwest Territories [23]. Only one application of
wastewater was made to the test plots. The soils were identified as fine
glacio-lacustrine sands with no permafrost at the Fort Simpson site, and
a 30-cm thick organic layer underlain by high ice content clayey till at
the Normal Wells site. The loading rates varied from 1.3 cm to 20.3 cm,
and results indicated no apparent adverse effects on the vegetation.
There were indications that pioneer vegetation in disturbed areas with
low nutrient availability may benefit from sewage irrigation. Suitable
loading rates were not examined.
Slow infiltration land application was studied at an interior
Alaska location [24]. The soil, classified as a sandy-silt, was able to
accept 15.2 cm of secondary lagoon effluent per week for the summer test
period. Performance data is presented in Table 10-3.
10.6 Swamp Discharge
The use of natural swamps for treating or polishing wastewater
has received considerable attention in recent years. Swamp discharge has
been practiced in several places in the North; however, detailed studies
have been limited. It is important to design the outfall diffuser for
maximum dispersion into the swamp.
10.6.1 Area affected
Discharge of untreated wastewaters to a swamp at Hay River,
Northwest Territories was investigated in detail by Hartland-Rowe and
Wright [26]. Assuming no equilibrium, they estimated that the effect of
r\
the effluent could be detected in an area of 35 m per each man-year
of sewage discharged. If equilibrium conditions were assumed after five
years of operation it was estimated that 110 m^ were ecologically
influenced by each contributing person.
Higher quality effluents would be expected to influence less
area. In a study by Fetter _et Jil. [27] the polishing capability of a
natural marsh of 156 ha with an average depth of 0.5 m was assessed. The
wastewater flow was approximately 1000 m^ per day, which constituted
about 20 percent of the flow into the marsh. The discharge was found to
attain the following reductions:
-------
10-17
TABLE 10-3. RESULTS OF SPRAY APPLICATION OF LAGOON EFFLUENT
AT EIELSON AIR FORCE BASE (15-cm lysimeters)*
Test
Cell
1974
A
B
C
1975
A
B
C
Application
rate
cm/m/wk
0.75 Mean
Max
Min
1.20 Mean
Max
Min
1 . 7 Mean
Max
Min
Mean
Max
Min
Mean
Max
Min
Mean
Max
Min
TOG
mg/L
22
47
13
25
34
10
23
36
13
-
-
-
_
-
—
_
-
—
BOD
mg/L
-
-
—
—
-
—
_
-
—
3
8
0
11
50
2
5
18
0
SS
mg/L
6
10
3
4
8
2
13
28
5
136
511
11
11
29
4
63
428
7
FC
per 100 ml
-
-
—
-
-
—
_
-
—
802
2 400
0
20 350
102 000
0
7 656
36 000
16
* References [24] and [25].
-------
10-18
Parameter Percent Reduction
BOD 80.1
Coliform 86.2
Nitrate 51.3
COD 43.7
Turbidity 43.5
Suspended Solids 29.1
Total Phosphorus 13.4
10.6.2 Management
In general, swamp areas can provide effective polishing of
effluent from treatment plants. If excessive BOD and suspended solids
are allowed to enter the area, normal aerobic-anerobic relationships may
be shifted severely to the anaerobic side. Such a condition could result
in the release of excessive odours and decreased performance of the
area.
The area should be well posted at 50 to 100-metre intervals.
The signs should identify the area as part of the wastewater treatment
system.
10.6.3 Effects
The principal effect of swamp use is that the area must be
assumed to be a part of the treatment system and access limited or
discouraged. Depending upon the quality of the effluent applied and the
degree of disinfection, the area will function as a facultative lagoon.
The wastewater discharge will increase the number of pathogenic
bacteria present. It will also add heat to the system during the winter.
Considerable icing may occur due to the shallow water. Ice
build-up may retard break-up in the spring.
10.7 Sludge Disposal
All wastewater management techniques require the disposal of
sludge. This section presents only those techniques which make use of
unique cold climate conditions.
-------
10-19
10.7.1 Sludge drying/freezing
Sludge drying is a common practice at most wastewater treatment
facilities. However, very few sludge drying facilities have been
constructed in cold regions. Sludge dewatering by freezing has been
investigated by several groups [28]. It was found in one study that
application of 10 to 15 cm of sludge during freezing conditions resulted
in good freeze-assisted coagulation.
10.7.2 Sludge pits
Sludge disposal pits are one of the most commonly used methods
of disposal. Pits can be excavated in almost any material. Permanent
ice, snow, permafrost, various soils and rock have been used. Several
years ago, considerable work was done by the U.S. Army Cold Regions
Research and Engineering Laboratory (U.S. ACRREL) on the use of ice
crypts [29].
Snow pits were also studied by U.S. ACRREL. In this case,
sewage diseharged to snow will travel downward, forming a sump until it
freezes. The depth of the sump is dependent on the rate of heat addition
(volume and temperature of the sewage). The vertical pit will develop
until the percolating liquid freezes to form an impermeable bottom [30].
The performance of pits in permafrost or periodically frozen
soil was investigated by Heinke and Prasad [31], Their recommendation is
presented below:
"Based on the results of a two year laboratory study, simulating
a waste pit, it is concluded that it does not provide satisfac-
tory treatment of human wastes (honey-bags). The waste pit
served as a holding tank only at -5°C operation. When the
pit was operated at +5°C for about three months each year to
simulate summer conditions, insignificant changes in the values
of the physical-chemical parameters were observed. The sole
significant change was a four-fold increase in the production of
volatile acids. A significant increase in the heterotrophio
bacterial population was observed each year in the latter part
of +5°C operation. No increase in psyohsophilic bacteria
was noticed. Pathogens are likely to remain viable in the pit
for many years.
"Although a waste pit is not a satisfactory treatment method, it
is considered better than disposal at an open dump or in a
lagoon, which is designed to receive sewage. Location of the
pit is most important. It should be as far away as practical
-------
10-20
from the community and on a site that will not be needed for
other purposes in the future and which does not drain towards
water supply sources. The pit should be sized on the basis of
20 cu ft per person per year. For a community of 5000 people, a
pit of 100 x 25 x 4 ft deep would be required. A freeboard of 2
feet should be allowed, the contents to be covered by 2 feet of
soil when the pit is full and a new one dug. Where soil condi-
tions require it, the pit should be lined with heavy plastic
sheets to prevent seepage through soil to prevent possible
contamination of ground and surface water. Truck access for
easy dumping is required. A honey-bag disposal station, on the
Greenland model and as described in the report, could be consi-
dered together with a waste pit installation. It would improve
considerably the solids handling aspect but at a sizeable
cost."
10.7.3 Lagoon sludge disposal
Disposal of sludge accumulated in lagoons has seldom been
eonsidered. Removal of sludge from lagoons is infrequent. Normal
practice is to move the sludge to a separate holding area, preferably
near the landfill, and cover it with 0.5 to 1.0 metres of soil.
10.7.4 Landfill
Although landfill dumping of undiluted and treatment plant
sludge is practiced, it is not a recommended procedure without proper
evaluation of the impacts. Principal considerations are proper isola-
tion, frequent cover, knowledge of soil conditions and permability,
groundwater depth and direction of movement, and access control for
people and animals.
10.8 References
1. LaPerriere, J.D., T. Tilsworth and L.A. Casper, The Nutrient
Chemistry of a Large, Deep Lake in Subarctic Alaska. Institute
of Water Resources Report No. IWR-80, Univ. of Alaska, Fairbanks,
1977.
2. Alexander, V., Dynamics of the Nitrogen Cycle in Lakes. Institute
of Marine Science Report Number R71-7, Univ. of Alaska,
Fairbanks, 1970.
3. Schallock, E., Low Winter Dissolved Oxygen in Some Alaskan Rivers.
U.S. Env. Prot. Agency Report No. EPA-660/3-74-008, Corvallis,
Oregon, 1974.
-------
10-21
4. Gordon, R.C., Depletion of Oxygen by Microorganisms in Alaskan
Rivers at Low Temperatures. IN: R.S. Murphy, Water Pollution
Control in Cold Climates Symposium, U.S. Env. Prot. Agency,
Washington, D.C., 1970.
5. Murray, A.P. and R.S. Murphy., The Biodegradation of Organic
Substrates Under Arctic and Subarctic Conditions. Institute of
Waster Resources Report No. IWR 20, Univ. of Alaska, Fairbanks,
1972.
6. Bouthillier, P.H. and K. Simpson, Oxygen Depletion in Ice Covered
Rivers. Jour, of the Sanit. Eng. Div.. ASCE, 98_, SA2, 341, 1972
7. Greenwood, J.K. and R.S. Murphy, Factors Affecting Water management
on the North Slope of Alaska. Institute of Water Resources
Report No. IWR 19, Univ. of Alaska, Fairbanks, 1972.
8. Cleary, E.J., Effluent Standards Strategy: Rejuvenation of an Old
Game Plan. Jour. Water Poll. Control Fed., 46, 1,9, 1974.
9. Gordon, R.C., Winter Survival of Feeal Indicator Bacteria in a
Subarctic Alaskan River. U.S. Env. Prot. Agency Report No.
EPA-R2-72-013, Corvallis, Oregon, 1972.
10. Davenport, C.V., E.B. Sparrow and R.C. Gordon, Fecal Indicator
Bacteria Persistence Under Natural Conditions in an Ice Cover
River. J. Appl. and Env. Micro., 1977.
11. Bell, J.B., W. Macrae and J.F.J. Zaal, The Persistence of Bacterial
Contamination in the North Saskatchewan River in the Vicinity of
Edmonton, Alberta. Environmental Protection Service, Edmonton,
Alberta, 1977.
12. Canada. Dept. of Environment. Interim Guidelines for Wastewater
Disposal in Northern Canadian. Water Pollution Control
Directorate. Environmental Protection Service, Dept. of the
Environment, Ottawa, Ontario, 1974.
13. Anon, Manual of Septic-Tank Practice. Public Health Service
Publication no. 526, Superintendent of Documents, U.S.
Government Printing Office, Washington, D.C., 1967.
14. Alberta Labour. General Safety Services Division, Plumbing
Inspection Branch, Private Sewage Disposal Systems Instruction
to Installers, 1978. Edmonton, Alberta, 1978.
15. Straughn, R.O., Septic Tanks at Remote Air Force Installations in
Alaska. Environmental Engineering Section, Arctic Health
Research Center, College, Alaska, 1967.
-------
10-22
16. Lamphere, E.M., Operation of Experimental Septic Tank Units Under
Subarctic Conditions. Proceedings, Third Alaskan Science
Conference, Sept. 22-27, 1952, Mt. MeKinley National Park.
Alaska Div. Am. Assoo. for the Advance of Science, Fairbanks,
1952.
17. Hindin, E., R.H. Green and G.H. Dunstan, Septic Tank Performance at
Low Temperatures. Report No. 27, Div. of Industrial Research,
Inst. of Technology, Washington State Univ., Pullman, 1962.
18. Hiekey, J.L.S., and D.L. Duncan, Performance of Single Family Septie
Tank Systems in Alaska. Jour. Water Pollution Control Federation
213, 8, 1298, 1966.
19. Grainge, J.W. and J.J. Cameron, Sewage Lagoons in Northern Regions.
Presented at the U.S. Environmental Protection Agency Technology
Transfer Design Seminar, Anchorage, Alaska, 1975.
20. Reid, L.D., Jr, Design and Operation of Aerated Lagoons for the
Arctic and Subarctic. Presented at the U.S. EPA Technology
Transfer Design Seminar, Anchorage, Alaska, 1975.
21. Murphy, R.S., G.V. Jones, S.F. Tarlton, Water Supply and Wastewater
Treatment at Alaskan Construction Camps. U.S. Army Cold Regions
Research and Engineering Lab. report in press, Hanover, New
Hampshire, 1977.
22. Technology Transfer Design Manual of Land Disposal, U.S. Env. Prot.
Agency, Washington, D.C., 1977.
23. Fahlman, R. and R. Edwards, Effects of Land Sewage Disposal on
Sub-Arctic Vegetation. IN: Arctic Waste Disposal, Report No.
74-10, Environmental-Social Program, Task Force on Northern Oil
Development, Government of Canada, Ottawa, Ontario, 1974.
24. Sletten, R.S., Feasibility Study of Land Treatment at a Subarctic
Alaskan Location. IN: R.C. Loehr, Land as a Waste management
Alternative, Ann Arbor Science Publishers, Michigan, 1977.
25. Smith, D.W., Land Disposal of Secondary Lagoon Effluents, Pilot
Project. Institute of Water Resources Report No. 59, Univ. of
Alaska, Fairbanks, 1975.
26. Hartland-Rowe, R.C.B. and P.B. Wright, Swamplands for Sewage
Effluents, Final Report. Environmental-Social Committee,
Northern Pipelines, Department of Indian Affairs and Northern
Development, Ottawa, Ontario, 1974.
27. Fetter, C.W., Jr., W.E. Sloey and F.L. Spangler, Use of a Natural
Marsh for Wastewater Polishing. Special Report of the Dept. of
Geology, Univ. of Wisconsin, Oshkosh, 1976.
-------
10-23
28. Tilsworth, T. , Sludge Production and Disposal for Small Cold Climate
Bio-Treatment Plants. Institute of Water Resources Report No.
IWR-32, Univ. of Alaska, Fairbanks, 1972.
29. Ostrom, T.R. , et_ al, Investigation of a Sewage Sump on the Greenland
Icecap. Jour. W.P.C.F., 34_, 1, 56, 1962.
30. Reed, S. and Tobiasson, Wastewater Disposal and Microbial Activity
at Ice-Cap Facilities, Jour. Water Poll. Control Fed. 40, p.
2013, 1968-70. ~
31. Heinke, G.W. and D. Prasad, Disposal of Human Wastes in Northern
Areas. IN: Some Problems of Solid and Liquid Waste Disposal in
the Northern Environment. Environment Canada Report EPS
4-NW-76-2 pp. 87-140, 1976. Also in Proe. 3rd Canadian
Hydrotech. Conf., Canadian Soc. Civ. Eng., Laval University,
Quebec, 1977. pp. 578-593.
-------
SECTION 11
CENTRAL FACILITIES AND REMOTE CAMPS
Index
Page
11 CENTRAL FACILITIES AND REMOTE CAMPS 11-1
11.1 Introduction 11-1
11.2 Central Facilities 11-2
11.2.1 Level of service 11-2
11.2.2 Design population and flows 11-7
11.2.3 Selecting and sizing services 11-8
11.2.4 Space considerations 11-14
11.2.5 Water supply and treatment 11-15
11.2.6 Wastewater treatment and disposal 11-16
11.2.7 Energy conservation 11-19
11.2.8 Fire protection 11-26
11.2.9 Construction techniques 11-27
11.2.10 Cost factors 11-29
11.3 Remote Camps 11-30
11.3.1 History 11-30
11.3.2 Facility description 11-31
11.4 References 11-34
11.5 Bibliography 11-35
-------
List of Figures
Figure Page
11-1 Environmental Service Module 11-4
11-2 Aerial View of Central Facility 11-6
11-3 Ground View of Central Facility 11-6
11-4 Typical Honeybucket Dump Station 11-18
11-5 Water, Wastewater and Heat Flow AVDP -Wainwright, Alaska 11-20
11-6 Example of Energy Recovery from a Diesel Generator 11-21
11-7 Schematic of Incineration Process 11-25
11-8 Relationship Between Fuel Consumption and Moisture
Content of Solid Waste During Incineration 11-25
11-9 Road/Pipeline Construction Camp 11-32
11-10 Drilling Rig Camp 11-32
11-11 Layout and Utilities for a Pipeline Construction Camp 11-33
Table
11-1
11-2
11-3
11-4
11-5
LIST OF TABLES
Central Facilities in Alaska: Services Provided
Distribution of Space in a Typical Central Facility
Typical Laundry Wastewater Characteristics
Construction and Operating Costs for Three
Central Facilities
Remote Camp Sizes and Durations
Page
11-5
11-15
11-17
11-29
11-34
-------
11-1
11 CENTRAL FACILITIES AND REMOTE CAMPS
11.1 Introduction
Many cold climate communities are located where it is difficult,
if not impossible, to construct and operate conventional water supply and
wastewater systems piped to the individual homes. Ice-rich permafrost,
soils with deep frost penetration, rock, and low density distribution of
housing are among the factors limiting the use of conventional water
supply and wastewater system services in some communities. Nearly all
such communities are native villages with less than 600 people.
One alternative for these communities is to provide at least one
facility, centrally located, where certain sanitation services can be
obtained. For example, a central facility might provide a place to obtain
safe water to drink, a sanitary means of waste disposal, a place to bathe
and a place to launder clothes. Any combination of these sanitation
services may be provided.
This section discusses the design considerations for providing a
central facility in communities where piped services to individual houses
are not feasible. Considered in the discussion are the level of service
to be provided, sizing of utilities and services, energy conservation,
fire protection, construction techniques and cost factors.
In addition to those people who have lived in the cold climate
regions for thousands of years, the search for oil, gas and minerals has
brought industrial workers to the far north in large numbers. Also man
eomes to the cold regions for purposes of national defense, research,
communications, and development of other natural resources. Early housing
and utility services were crude. Now, however, improved temporary and
permanent camp facilities enable workers to live in relative comfort,
safety and health with a minimum impact on the environment.
The central facility concept for achieving sanitation services
has application in remote camps as well as in villages. The need for
sanitation services and environmental protection is similar in remote
camps and in the villages, but they are discussed separately in this
manual because the economic, social, cultural, institutional, and operation
and maintenance aspects of the facilities are so different.
-------
11-2
Remote camps include those used by the natural resource
development industries in support of their efforts to explore, develop,
and produce natural resources. In addition, there are large temporary
pipeline construction camps, small permanent pump station camps and
industrial services camps. The military uses remote camps to support
its DEW line facilities, and is interested in more efficient remote camps
for troops in the Arctic. There are also remote eamps for road
constructors and developers of other natural resources.
11.2 Central Facilities
11.2.1 Level of service
Central facilities can provide a variety of levels of service,
depending on the needs and desires of a community, convenience, the cost
of operating and maintaining the system, and funds available.
Defining the level of service to be provided is not always easy,
but it is one of the most important considerations in the early stages of
a project. Decisions on the types of services to be provided should be
made only after carefully considering funds available for construction;
operation and maintenance available within the community and from outside
sources; what the community wants; social and cultural customs; community
willingness to participate in the project; availability of good operators;
and availability of technical and management expertise. Section 2
provides other useful information to consider during the planning stage of
a project.
Realistic consideration of these factors with the meaningful
participation and involvement of the community in the decision-making
process is essential to, but in no way a guarantee of, a successful
project. A successful project is one which satisfies the sanitation needs
of the people for whom it is built.
A minimum level of service for a central facility might be a
simple watering point from which people can obtain safe water to drink.
This single service may be appropriate for some communities based on the
above considerations. It is discussed in detail in Section 6.
Other services to be considered include providing a place to
wash and dry clothes, bathing facilities, a place to safely dispose of
-------
11-3
honeybucket and other wastes, toilets and wash basins. Saunas can
supplement the use of showers, but local custom, and willingness to use
them and pay for their use, must be carefully considered before they are
installed in the facility. Figure 11-1 from Brown, et al [1] shows a
floor plan for a typical central facility. Table 11-1 lists the services
provided in 14 typical central facilities constructed in Alaska.
Central facilities often may be constructed as the first
installment on a more complete system. Therefore, each central facility
should be designed so that its basic water supply and wastewater treatment
systems can be expanded to provide increased service. Typical expanded
services might be a haul system, or in some cases, a water and sewer
system piped to individual houses.
Whenever possible, arrangements should be made for the central
facility to serve or be served by other major community facilities such as
schools, health clinics and power generating facilities. The revenue
produced by serving these facilities can be substantial and provide
stability to the income derived from community use of the central
facility. Also, the use of electricity and waste heat from community or
other large power plants can result in fuel savings and significant
increases in overall system efficiency.
Experience with central facilities has been limited to
communities between about 25 and 600 people. Most of the facilities have
been one or two storey structures with between 80 and 325 square metres of
total floor space. Roughly half the space is used directly by the
consumer, while the mechanical operations, storage space and operator work
areas account for the remainder. Typical central facilities are
illustrated in Figures 11-2 and 11-3.
When facilities are constructed in remote areas of the North,
where the climate can be exceedingly unforgiving and where electrical
power service may be unreliable, the most important design criteria are to
simplify construction and operation, and provide a high degree of
reliability. Unfortunately, this is easier said than done. To deal
effectively with the harsh climate and with some of the difficult water
supply and waste disposal problems encountered in the Arctic, some degree
of complexity is frequently unavoidable.
-------
03
CD
s_
03
c:
o
Toilets and bathing
CD ^^>
O /
£ /
Laundry
cc d
Toilets and bathing
Sauna
Water
production
O Process
—, control i
laboratory
O
Waste treatment
/oauna
s v.
o
o
Drive-way
FIGURE 11-1. ENVIRONMENTAL SERVICE MODULE [1]
I
-p-
-------
TABLE 11-1. CENTRAL FACILITIES IN ALASKA: SERVICES PROVIDED
Community
Wainwright I*
Wainwright II
Emmonak
Northway
Chevak
Nulato
Selawik
Alakanuk
Pitkas Point
Koyukuk
Beaver
Kongiganak
Tanana
Council
Population
341
545
40
447
330
521
512
85
124
101
200
450
25
Water Point
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
Washers
4
4
4
3
3
4
4
4
3
3
3
4
6
no
Dryers
4
5
3
3
3
4
4
4
3
3
3
4
6
no
Showers
8
8
8
2
,2
4
4
4
4
3
3
6
8
no
Toilets
8
8
6
2
0
6
6
6
4
3
3
4
4
(privies)
yes
Saunas
2
2
2
no
no
2
2
2
2
no
2
no
no
no
Incinerator
yes
no
yes
no
no
yes
yes
yes
no
no
no
no
no
no
Honey-
bucket
Dump
yes
yes
yes
no
no
yes
yes
yes
yes
yes
yes
yes
yes
no
Other
Facilities
Served
Schools
Schools
Schools,
Community
centre
Clinic
Clinic
School ,
Clinic
School ,
Clinic-
School,
Clinic
School
School
School
School
School
none
*Wainwright I was destroyed by fire in 1973.
-------
11-6
FIGURE 11-2. AERIAL VIEW OF CENTRAL FACILITY
FIGURE 11-3. GROUND VIEW OF CENTRAL FACILITY
-------
11-7
11.2.2 Design population and flows
Specific design criteria for the services selected are as varied
as the communities. First, the design population, water supply
requirements, and the amount and type of wastewater must be considered.
The following example, from the Alaska Department of
Environmental Conservation (ADEC) [2], is presented to illustrate one way
to estimate these design criteria. The approach was used to design a
central facility for the small community of Pitkas Point on the lower
Yukon River in Alaska. (Minor modifications have been made in the example
for this manual.)
The community had a population of approximately 80 people.
There were about 15 houses within a radius of 0.5 km. A small creek by
the community provided a good, reliable source of water. There was a
one-teacher school located near the centre of the community. No
permafrost existed and soils were generally silty sandy gravel with a
water table over 7 m deep. Electrical power was available from the nearby
community of St. Marys and a good gravel road connected the two; no other
utility services were available. Water was carried in pails from the
creek to the homes and honeybuckets were dumped into the Yukon River.
Allowing for growth, the following assumptions for design
populations and per person loadings were used:
- 120 people and 20 families @ 10 L/person/day;
- one teacher plus a family of three @ 375 L/person/day;
- 40 students @ 60 L/student/day;
- one honeybucket per family/day @ 20 L/bucket and
50 000 mg/L BOD loading (includes some grey water);
- two showers/person/week;
- three water closet uses/person/week (assume low
water use toilets);
- one washer load/family/day.
Daily water flows were determined as follows:
Laundry: 20 x 160 L/use = 3 200
Showers: 120 x 2/7 x 120 L/use = 4 115
Water Closets: 120 x 3/7 x 15 L/use = 475
-------
11-8
Teacher (and family): 4 x 375 L/person = 1 500
Students: 40 x 60 L/person = 2 400
Honeybuckets: 20 x 20 L/family = 400
Miscellaneous: = 375
Subtotal (wastewater) = 12 365 L/d
Offsite use: 102 x 10 L/person = 1 200
Subtotal = 13 565 L/d
Total Water Consumption (less honey-
bucket wastes) = 13,565 - 400 = 13,165 L/d
Based on the assumptions and calculations outlined above, a
water supply rate of 14 000 L/day and wastewater flow of 13 000 L/day were
selected for design purposes.
At the present time no definitive studies exist to provide the
designer with exact criteria on water supply and waste flows for central
facilities. Until such data can be obtained from existing and future
central facilities, rational approaches to arrive at these design
criteria, such as illustrated above, can be used.
11.2.3 Selecting and sizing services
Selecting sizes and types of service (showers, laundry, saunas,
sewage dump station, washrooms, etc.) must be done on a case-by-case basis.
Careful consultation with people in the community (perhaps even with the
use of a well designed, administered and interpreted questionnaire [3]) is
essential to providing the best possible service. The questions that must
be answered include: How many hours per day and per week will the facility
be open? How often will people use the services provided per day and per
week? How much are the people willing to pay for the services? Given the
community responses to the questions, some design estimates can be made.
One formula used by ADEC [3] for determining the number of units
(showers, washers, and dryers, etc.) is as follows:
NUMBER = uses/week x cycle time/use x p.p. (11-1)
time available/week
where: P.F. is a peaking factor to account for the fact that use of a
service will not be spaced evenly throughout an entire week.
Typical P.F. values for design might range between 1.5 and 3.5.
-------
11-9
11.2.3.1 Washers. Commercial washers should be used. They range in
capacity from 6.8 kg (weight of dry clothes that can be placed in them)
up to about 15.9 kg. An average washer cycle is about 40 minutes
including loading and unloading time. Smaller units are significantly
cheaper, but larger ones can handle bulky items such as sleeping bags,
small blankets, and parkas, and have proved particularly useful.
Horizontal axis washers, and especially washer-water
extractors, tend to vibrate during use [4], It is, therefore, necessary
to provide a solid base such as concrete or heavy timbers to prevent the
vibration. Vertical axis washers do not vibrate as much, but they are
normally available only in smaller sizes. Top loading vertical axis
washers also use about 40% more water than the front loading horizontal
axis machines for an average wash load [5].
Past facility designs have frequently used two loads/family/
week to estimate the number of washing machines needed. In smaller
communities where the facility will be conveniently located, designs of
one load/family/day have been used. As noted earlier it is important to
seek guidance from the community involved to arrive at a suitable use
factor. As a practical matter, a minimum of three washers and three
dryers should be provided, regardless of community size. This will
enable service to continue on a more or less uninterrupted basis when one
or more of the machines is out of service. Dependability of service is
important to user satisfaction with the central facility. Also, the
units should be installed so that they are readily accessible for
maintenance and repair.
11.2.3.2 Dryers. There are many types of dryers available: hot water,
electric, steam, hot air, and hot liquid. It is difficult to choose the
"best" type for a particular application.
Electrically operated dryers are the easiest to maintain but
they are also the most expensive to operate. According to ADEC [2],
electrical energy can cost over ten times as much as that derived from
bulk fuel oil. ADEC [3] calculated that for an 8.2 kg capacity dryer
requiring 21.6 MJ/h (5.9 KW), 45 minutes/load and $0.056/MJ ($0.20/KWh),
a very low electrical cost in remote areas, the electrical cost for
-------
11-10
heating alone would be $0.89/load. Comparable heating costs using oil
were calculated to be about $0.11/load.
Hot water has been used for dryers in several central
facilities with satisfactory results. One major disadvantage of hot
water is the likelihood of broken or damaged pipes and heat exchangers in
the event of freezing. Hot water as a source of dryer heat is also of
marginal quality. In order to provide sufficient heat to the dryers, the
hot water system must be operated at its upper limit for temperature and
pressure. This increases the chance of vapour locks in the system due to
"flashing". Hot water dryers are not commercially available, although
steam operated dryers can be used with virtually no modification. The
primary advantage of hot water dryers is that they can be run directly
off of a single hot water furnace, which may also provide building heat
and a domestic hot water supply. Also, remote community operators are
generally more skilled in the operation of hot water heating systems than
steam heating systems.
A hot air furnace with appropriate duct work can provide dryer
heat. Such a system requires one less heat exchanger and is not damaged
by freezing, but ducting must be well insulated to reduce heat losses
and, most important, an extra furnace is required [3], Advantages and
disadvantages of separate vs multipurpose furnaces are discussed in
Section 11.2.7.3. Dryers heated by hot air furnaces are not commercially
available, but typical electric dryers can be converted readily for this
application.
Steam operated dryers would appear to be a good choice because
of the excellent heat carrying capacity of steam. However, few people in
the remote areas are familiar with the principles and operating
characteristics of steam systems. In addition, the relatively high
operating temperatures and pressures require more maintenance. Freezing
can damage steam dryers (although the potential is somewhat less than
with hot water) and the heat exchanger coils tend to require frequent
cleaning to maintain efficiency.
Hot organic fluids such as "Dowtherm" or "Therminol" can also
supply dryer heat [6,7]. These systems can be efficient, although they
-------
11-11
operate at relatively high temperatures (177°C). Numerous operational,
maintenance, and safety problems can occur, particularly if initial
construction is poor [5], One advantage, besides efficiency, is that
freezeups do not result in damage to this type of heating system.
Experience indicates that dryers generally should be sized at
least 1.5 to two times larger than the washers. This will accommodate
the tendency for people to put more than one washer load in a dryer and
will also account for the fact that it generally takes longer to dry
clothes than to wash them. Appropriate dryer sizes can be determined
after the washers are selected.
Drying cycle times vary with the type of system used.
Manufacturers' literature can provide this information. For hot water
systems, the cycle time will be about 45 minutes. An additional 10
minutes to load and unload clothes can be used when estimating total
cycle times.
There are many acceptable brands of washers and dryers readily
available on the market. After the type and size of equipment have been
selected, the choice of model should be based on the availability of
spare parts and the range of sizes available.
11.2.3.3 Showers. The number of showers required can be estimated using
Equation 11-1. The showers normally should be divided between men's and
women's shower rooms. Previous designs have frequently used two
showers/person/week for usage rates and an average use time of about 10
minutes.
Because of the great expense of heating water, shower flows
should be limited to the extent practicable. Inaccessibility of a water
source and difficult treatment requirements will also dictate the need
for water conservation. Timers, flow regulators and flow shower heads
are the most useful devices for oonserving water. Reid [6] reports
adequate and satisfying showers using only 23 L/shower with these
devices. Conventional shower heads use about 25 L/minute, while low flow
shower heads with flow rates of 5 to 12 L/minute are readily available at
a cost of approximately $10 [5],
-------
11-12
Minuse Systems Inc. [8] reports a device which ean give an
adequate shower using only 1-2 L/minute. The special shower head mixes
water with air from a small electrically operated blower to create a fine
stream effect. A glass or rigid door is required for the shower stalls.
The increased complexity and oost of this system must be compared with
the apparent water and energy savings. Alternatively, with a simple self-
closing hand-held shower unit, developed by the U.S. Navy, an adequate
shower can be obtained with only 10 L of water [9]. More detailed infor-
mation is available in Appendix B.
11.2.3.4 Saunas. Early central facilities included saunas primarily as
a means to reduce water consumption, based on the premise that actual
"bathing and cleansing" would take place in the sauna and the showers
would then be used simply to rinse off. Since saunas use virtually no
water, savings were anticipated to be substantial. However, experience
has shown that persons taking saunas take showers not only to rinse, but
to cool off as well.
The other reason saunas were included is that they are a part
of the native culture in many southwest Alaska communities. In those
communities where saunas are not part of the local custom, they are not
used enough to justify their installation. If not used, saunas do not
generate enough money to pay for operation and maintenance. Reid [6]
reports that saunas consumed 14.2 percent of the total fuel used in the
central facility at Emmonak, Alaska.
Nevertheless, the saunas in the central facilities at Emmonak,
Alakanuk, and Pitkas Point in Alaska are extremely popular and
successful. Saunas are a local custom in these communities and the
people are attracted to the central facilities to use the saunas and
socialize. These saunas produce substantial revenue; for example, in
Alakanuk and Pitkas Point, approximately 2/3 of the total revenue from
the village is attributable to use of the saunas. These people are
clearly willing to pay the cost of providing the sauna service, and
more.
Saunas represent a special challenge because it is very
difficult to provide the high quality of heat needed to make them operate
-------
11-13
satisfactorily. Saunas constructed in central facilities so far have
used sauna stoves as a source of heat except for one that has used waste
heat from an incinerator [4], Electric sauna stoves are the easiest to
maintain; however, they can be prohibitively expensive to operate. Also
used are fuel oil fired sauna stoves. They perform adequately and are
reasonably efficient, but can be a safety hazard. Overheating can cause
cracks in the fire box allowing fumes to escape into the sauna room.
One promising concept uses hot water from the central building
heating system in series with an electric heater. The bulk of the
heating needs can be provided by the low cost oil-fired system. The
electric heater must only provide the small increment of heat which is
not available from a conventional hot water system.
With a regulated heat source and plenty of insulation, the cost
of operating a sauna can be reduced. Maintenance, of course, is
negligible other than that needed for the heating source.
11.2.3.5 Restrooms. Most central facilities providing more than just
a simple watering point also should provide restrooms. There should be
separate men's and women's restrooms, each with lavatories and toilets.
Equation 11-1 can be used to derive the number needed. In central
faeilities serving large communities, urinals should be provided for the
men's room.
Lavatories are not unique to central facilities and need little
discussion except to suggest that where water is scarce or expensive to
treat, they should have automatic closing valves.
Where water is readily available at low cost, flush tank
toilets are appropriate. They are simple to operate and require no
additional power source. Nevertheless, conventional flush toilets which
use an average of 20 L/flush are unnecessary. Flush toilets which
operate on the same simple principles as the conventional variety but use
only about 3 to 12 L/flush are readily availalbe [5, 10]. For virtually
the same operation and maintenance costs, considerable savings can be
realized over procuring, treating and pumping the water, and treating and
disposing of the wastewater.
-------
11-14
Where water is in short supply, or procurement or treatment
costs are high, other types of toilets should be considered. One such
toilet has a vacuum rather than gravity collection system and only uses
about 1.5 L/flush [5], Recireulating chemical toilets use only about 10
to 30 L of water per 150 flushes [5], The contents of the reoirculating
toilets can be transported to the treatment system by vacuum, gravity, or
manually. Substantial water savings can be realized with these systems,
but there are chemical costs and mechanical systems to be maintained.
Units are available which flush mechanically or electrically. Reid [7]
concluded that recirculating toilets installed in central facilities were
of poor design for the application and were fragile. Refer to Appendix B
for details on available toilet units.
11.2.3.6 Water storage. Central facilities should have storage
capacity for treated water. Depending on the reliability and
availability of the water source, water source flow capacity, and fire
flows, storage may range from less than one day's to nine months' design
flow. The amount of storage should be sufficient to ensure a minimum
level of service for the duration of any anticipated power outage or
equipment breakdown. Storage capacity amounting to about one day's total
design flow has been used frequently for central facilities where water
sources are reasonably available and water treatment requirements are not
unusually difficult. Water conservation will ensure several days reserve
to provide minimum services such as drinking water supply and showers.
Details for sizing and designing water storage systems are contained in
Section 5.
11.2.4 Space considerations
Lack of sufficient spaee has been a serious problem in previous
central facilities. The early emphasis on saving space resulted in
problems for both operators and users of the facilities. Equipment and
facilities were squeezed together so much that vital repair and
maintenance functions oould not be performed without major efforts to
move piping and equipment. Inaccessibility breeds frustration and
inattention by operators and necessary maintenance routines are not
performed.
-------
11-15
Vital components must be easily accessible. Piping must be
arranged so it does not interfere with basic maintenance and repair
functions. Critical piping joints should not be located in walls. If
they must be placed in walls, then removable panels should be provided
for easy access. In addition, cramped space in the user's portion of the
facility discourages use.
One of the more frequently overlooked space requirements for
central facilities in remote areas is storage space. Transportation of
bulky items like chemicals and general supplies to many remote
communities is often limited to once per year. Hence, storage areas need
to be sized to accommodate this quantity of supplies. Another often
overlooked requirement is space to work on pumps and motors and to
perform other general repair and maintenance functions. Table 11-2 shows
the distribution of space among services and operating functions in a
typical central facility with average water supply and wastewater
treatment requirements.
TABLE 11-2. DISTRIBUTION OF SPACE IN A TYPICAL CENTRAL FACILITY
SPACE PERCENT OF TOTAL
OPERATION
Chemical/materials storage 10
Operator repair/office 10
Water treatment 5
Wastewater treatment 10
Heating/ventilating 5
Subtotal 40
SERVICE
Laundry 25
Sauna/shower 15
Restrooms 10
Subtotal 50
MISCELLANEOUS 10
TOTAL 100 percent
11.2.5 Water supply and treatment
A central facility must provide water that is chemically and
bacteriologically safe, which is more convenient than other sources,
-------
11-16
and which tastes and appears better than alternate sources. Providing
the degree of water treatment to meet these requirements is essential if
the facility is to be used.
The central facility concept has some options for water supply
and treatment that are not normally available to piped utility systems.
For example, where good water is scarce or treatment is difficult, the
central facility can use a small system for potable water only (showers,
lavatories and drinking). Other needs for toilet flushing and laundering
might be met with recycled water or water of less than drinking water
quality.
Special effort should be made to ensure the best raw water
quality possible before it is brought to the central facility for
additional treatment prior to being used. For example, an infiltration
gallery might be used, where appropriate, to provide a minimum level of
pretreatment and reduce the need for more extensive in-house treatment.
Otherwise, water supply and treatment requirements for central
facilities are not particularly unique compared with other water supply
needs in the Arctic. Details on water supply and treatment systems are
discussed in Sections 3, 4 and 6.
11.2.6 Wastewater treatment and disposal
Detailed wastewater treatment and disposal alternatives are
discussed in Sections 9 and 10. These alternatives, with modification,
are appropriate for central facilities. For example, special
consideration must be given to treating laundry wastes, large variations
in influent temperatures, foaming, shock loads from honeybucket wastes,
and the fact that, hydraulically, flows will be limited to the operating
periods of the facility unless other users, such as schools, are serviced,
A major portion of the wastewater flow in a typical central
facility will come from the washing machines. Laundry wastewater
resembles domestic wastewater in many ways (see Table 11-3) [11] but it
does not contain all of the essential nutrients to sustain the organisms
necessary for effective biological treatment. This problem can be
overcome by adding domestic wastewater from toilets and honeybuckets, and
by serving other facilities such as schools.
-------
11-17
TABLE 11-3. TYPICAL LAUNDRY WASTEWATER CHARACTERISTICS
Range (mg/L)
Substance
ABS
Suspended Solids
Dissolved Solids
COD
Alkalinity
Chloride
Phosphates
PH
Nitrates
Free Ammonia
Sulfates
BOD*
Temperature*
Coliforms*
Minimum
3.0
15.0
104.0
65.0
61.0
52.0
1.4
5.1
—
—
80.0
20°C
Average
44.0
173.0
812.0
447.0
182.0
57.0
148.0
1.0
3.0
200.0
1260
21°C
2000/100 ml
Maximum
126.0
784.0
2064.0
1405.0
398.0
185.0
430.0
10.0
—
—
371.0
22°C
*Based on data reported by Aulenbaok, et al [11].
Sudsing detergents can cause excessive foaming. The use of low
suds detergents is essential to control this problem. Large temperature
variations due to laundry (hot), toilet flushes (cold) and showers (warm)
ean be upsetting to treatment systems.
Central facilities should be designed to handle honeybucket
wastes, but experience shows it is very difficult to get people to use it
for that purpose. Many people seem to be self-conscious about carrying
their own honeybuckets to the central facility for disposal and prefer,
instead, to dump the wastes near their homes. Figure 11-4 shows a
typical honeybucket dump station in a central facility.
A large flow equalization system is essential to overcome
treatment problems due to flow variations. Where package sewage
treatment systems are used, the rule of thumb for conventional design is
10-20 percent of the average daily flow volume. For central facilities
where the entire flow can be assumed to eome in 10 hours or less, it could
be necessary to provide holding capacity for over 50 percent of the
average daily flow for proper equalization. Therefore, for design
purposes the flow should be spread over a 24-hour period (at least for
small biological package treatment systems). The volume of the
equalization system depends on the actual flow regime, with at least
50 percent of the average daily flow volume being needed in many,
-------
11-18
if not most, cases. In addition, multiple package treatment systems in
parallel can often be used effectively to handle large variations in flow.
Data on the characteristics of wastewater from central facilities
are very limited. Nevertheless, data from three facilities which provide
all services offered in central facilities in addition to servicing adjacent
schools suggest that BOD, COD and total solids are roughly 300 mg/L, 700
mg/L and 1600 mg/L, respectively [4]. Suspended solids ranged from about
400 mg/L to 1365 mg/L, with no apparent reason for the higher value which
was an average of five samples.
Treatment of wastewater at central facilities can consist of any of
the conventional techniques, including lagoons, aerated lagoons, lagoons
with pretreatment (such as simple aeration), biological extended aeration
and physical-chemical. Even wet oxidation has been suggested for remote
military camps by Brown et al [1], No single technique can be recommended.
Once effluent standards are established, however, the system which offers the
least operation and maintenance requirements should be used where possible.
25L Toilet flush tank
Galvanized metal wainscot
1200 above floor
25 Supply line connected
to flush ring in cone
50 x 100 Nailed to wall
Provide handle in dump room
to operate flush tank
Wall brace
1 0 Copper line for bucket rinse
Fabricated strainer from
No 8 Copper rod spaced
50 apart Braze all joints
25 Copper pipe around perimeter
Provide 3mm holes in bottom at
25 OC solder to cone
Overlap to top and secure
with nichol plate F H screws
Galvanized 20 guage steel cone
100 Spigot
No hub coupling
100 ABS-DWV to trap
Note Seal all pints with silicone sealant
FIGURE 11-4. TYPICAL HONEYBUCKET DUMP STATION
-------
11-19
Puchtler et al [4] concluded that the cost of operating and
maintaining water-related utilities in rural Alaska is directly related
to the level of waste treatment provided. Although costs can be
substantially higher for complex wastewater treatment systems, the Alaska
Department of Environmental Conservation operating experience suggests
that wastewater treatment is not a major factor when compared with the
total cost of providing the other services in a central facility.
11.2.7 Energy Conservation
Section 14 provides details on this subject. The following
discussion pertains primarily to those aspects of energy conservation
related to central facilities. Figure 11-5 shows a detailed energy
balance diagram for a central facility at Wainwright, Alaska, using
several energy conservation techniques.
11.2.7.1 Electrical power. A dependable source of electrical power is a
critical ingredient in operating a central facility in remote areas.
Seldom, however, do the small communities in cold climates have reliable
sources of electricity, due primarily to the difficulty of operating and
maintaining diesel-powered generator systems. In many communities,
operators are poorly paid and funds are rarely sufficient to support even
minimum preventive maintenance routines. Other communities do not have a
source of electrical power and it must, therefore, be provided as part of
the central facility.
In all cases, standby power is essential. A standby source of
power for building heat would be the minimum acceptable. Capability to
provide the other central facility services is based on the importance of
the service to the community and judgement on the reliability of the
primary electrical energy source.
Electrical power in remote areas frequently varies greatly in
voltage and frequency. Such fluctuations reduce the useable life of
electrical high and low voltage and frequency protectors. Here again,
however caution must be exercised. Rarely can the operators of central
facilities repair or adjust these electrical controls without training
and assistance. Skilled electricians must sometimes be sent to the com-
munity to perform necessary repairs. This is a significant disadvantage of
-------
-UTILIDOR DUCT OO' long - 2"4> Water Lines
84'$x24'Ht 1
Capacity - Max
25' - U Factors
Roof 0 066 , F
Maintained obo-
OOO.OCO Gol /
^d DifferentKil /
Walls 0092, 1
oor 0 147 f
*e Freezing ^ ) —
1464 - Operating H
STORAGE TANK 'JJ *" '
Not; Full tank sufficient for
8 month operation based
anon annual usage factor
of 60%
Des 651
f
""
••)—
(55n F I
Des 651
(55-F ^
covered with 2 nsulation in
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and Alum num Clad
2115-24 Hrs/Day
-^ 143°F)
1
Flow dur ng 24 Hr Period
, 2115 hi at 43'F a heated to
) < 55°F U = 0 15
f 55°F 1 1
RAW WATER STORAGE
| 2800 Gal
Overflow to Beach j
Des 350 *
160' F I
1 TREA
Des 468
f *~ (65-F) >
1
~ \-
TED WATER STORAGE
1400 Gal
RAW WATER TREATMENT 1
l_
\~~^^~
1000 GPD to Schoo
2000 GPD to Homes "5 — ^—
POTABLE WATER STORAGE
2800 Go
Mox 725
Av9 351,
(Row during Oper-~l (55°F) "
Avo»9 °""9pl!"°<)»'ly
„"?:? In of 55-F heated
ulu h IOIK3-F 24Hrs/ Mox 635
Day Insulated with ^ JQQ
" U = OII5g (55
POTABLE
WATER HEATER
F
Max 90
Avg 42
C55"F) ' '
I f ( (
Max 540 1 Max 66 Max 60|_ Max 15
Avg 270V ' 'Avg 32 Avg 2OT ' 'Avg 5
(I10°F) I (55°F (llO°F) I (55°F)
SHOWERS -
8 LAVATORIES- 4
Operating Period Only Operating Period Only
Mo« Usage 75% of Time Max Usoge 12^% of Time
Avg Usage37 /?/,<$ Time Avg Usage 4 l/4%of Time
Mixed ShwrTemp )04°F Mixed Temp 99°F
Based on One Heod Use Based on One Sink Use
of I/^GPM 1 0°F 8 of 2GPM IIO°F a
0 I6GPM 55°F VzGPM 55°F
I
Max 700 1
Avg 332 1
&5°F T
T
Max I5j_ Max 4
Avg 4T ' 'Avg 1
lllOeF)I (55°F
_ABORATORY SINK- 1
Operating Period Only
vtax Usoge l2'/2%ofTime
fivg Usoge 3 'A %of Time
Mixed Temp 99°F
Based on Sink Use of
2GPM IIO°F a
'/SGPM 55° F
T
/•
TRE
Max I3£
Avg 9C
' '(160-F
_, ' -^ Max 178
' ^^ Ava 1 18
Flow during Oper- <6n°n
ating Perod only (6° F)
n of 60°F heated
to!60°F24Hrs/
Day Insulated with
2"Fiberqlass ^
U-II5 ^^
ATED WATER HEATER
575 Gol
Max 43
Avg 28
(60-F)
"j
Max 20 1 1 Max 5
Avg I5T T^vg 4
[||0°F)I I(55°F]
LAUNDRY SINK - 1
Operating Period Only
Max Usoge l67%ofTtme
Avg Usage l27%ofT.me
Mixed Temp 99° F
Based on Sink Use of
2GPM IIO°Fa
'/SGPM 55°F
Neal(55°F)
SAUNAS - 2
Heated 24 Hrs/Day In Use
ForOoeratina period On Iv
Normal Temp BO°F with N
240°F Capability mate A
up Air at 60"F Based N
on 4 Air Changes /Hr C
Operating Period K3% S
Losses During Off -Peak
V
2700 GPD (at Off -Peak
Ppnnd) r^turrtM fmm ••.*
(55° F by Truck * ^-
Oes 468 n at 70° F
^ ^ 1 65-F
I4OO Gal
V
1
^-JF
CARBON FILTERS CLEAR FLOW UNIT
\ ^ ^
Max 60
Avg 40
160° F
Max 20 Max 75 Max 21 Max 2
1 ' 'Avg 13 AvgSO1 ' < 'Avq 14 Avg 1 ' '
160-F) (leVF (60-F) (60-F)
WASHERS SMALL-2 WASHERS LARGE-2 W C S - 6
Dperatmg Period Only Operating Period On y Operating Period Only
tax Usoge 75% of Time Max Usage 75% of Time Max Usoge837%of Tme
•flgUsage 5O%of Time Avg Usage 5O%ofTime Avg Usage 50% of T me
achine Cycle 22 '/a Mm Machine Cyde 30 Mm Based on 6 Uses/ Hr
ycle Uses 15 Gal I60°F Cycle Uses 25GaJ I60°F (l6Uses Equal 1 Go )
5 Go 60°F Water a 7 Gal 60°F Water
T T V Y v
^ * I. V J ]To Incinerator |
^ 7
Occasional Washdown Only
WASHER SURGE 1
— — ^.
200 Go Tola
1 Max 201 1
Des 136 . J
1 1 90°F
Des 332 ^
I The operating period is defined as lOhrs per day, 7 days
per week The off-peak period is the remaining Whrs per
day
2 Water flows are indicated beside the f tow lines An flows
are in G P H unless otherwise slated Maximum is the flow
tobeexpexted in anyone hour durng the operating period
and is used for the design of individual units Average is
the flow to be expected over the lOhr operating period
and is used for the overall system design Design is the
avg uniform flow to maintain a operate the system
3 Additional design criteria is given inside the illustrated
equipment boxes
4 Area heating calculations are based en
Outside ombient at -30° F
Minimum outside temp -56°F
Building U-foctors (all U-factors in BTU/°F/ftVrir)
Inside walls =0306 , Ceiling = 0036
Outside walls = 0057,
Sauna U - factors
Inside walls = 0 073,
Outside walls=0 033.
Floor =003O
Ceiling = 0025
Floor = 0 030
Drive thru U-foctors as for building
The community complex area (washrooms, laundry,
entrance a center hall) is heated directly The drive
thru area is to be heated with a standard type unit
healer The raw and threated water areas are heated
both directly by the community complex area heater
and indirectly by heat transfer from process The inciner-
ator area is heated indirectly by heat transfer only
5 This flow sheet is intended only as an overall criteria
guide and does not indicate such items as pumps,
valves etc
HEAT DATA IN BTUs / HR
Heat Use
Dryers
Community Complex
Heater
Treated Water
Heater
Potable Water
Heater
Raw Water Tank
Process ( 67.180)
Outside
Storage (140,7001
Saunas
Drive Thru Heater
Future
Total
Operating
Period
I40.0OO
151,600
76,900
143,500
207.B80
24,190
12,960
757.050
Off Peak
Period
—
24,750
1.900
1,900
142,680
6.020
4,430
181,680
Unit
Desian
105,000
(210.000)
183,000
168. 60O
218.200
265, 300
25.600
(51,200)
17,900
N A
COMMUNITY COMPLEX HEATER
Based on maintaining Temp in Complex , Row Water
and Treated Water Areas at 60°F 24 Hrs /Day
Washroom Shower Areas to be maintained at TO'F
during Operating Period PlemmTempat 100° F
4 Air Changes / Hr during the Operating Period 10%
Loss during the Otf -Peak Period Make Up Air
at Outside Ambient
NJ
O
SHOWER SURGE TANKJ
480 Go I lota I
FIGURE 11-5. WATER, WASTEWATER AND HEAT FLOW AVDP - WAINWRIGHT, ALASKA.
-------
11-21
voltage and frequency protectors and must be considered carefully against
the need to replace or repair damaged electrical equipment. In spite of
these problems the U.S. Public Health Service and ADEC use voltage
protectors because of their experience with damaging voltage fluctuations
in villages.
11.2.7.2 Heat Recovery. Heat recovery is discussed in detail in Section
14. Central facilities offer a unique opportunity to capitalize on waste
heat recovery because of the relative closeness and availability of heat
sources within the facility. These sources may include generators,
heating furnaces, building exhaust air, dryer exhaust air, incinerators
and warm water. Recoverable waste heat can be used to supplement heating
needs of a central facility including heat for saunas, hot water, clothes
dryers, and building air. Figure 11-6 illustrates an example where 80
percent of the total energy can be recovered from a diesel generator. By
using efficient heat exchanges Reid [6] estimated that it is possible to
recover up to 50 percent of the net heat input to an incinerator.
Recoverable
exhaust
FIGURE 11-6. EXAMPLE OF ENERGY RECOVERY FROM A DIESEL GENERATOR
-------
11-22
11.2.7.3 Heating system. Another Important design consideration for
central facilities is choosing a heating system. The basic questions to
be answered are: What type of system is most desirable - hot water, hot
air or steam? and should there be a single source of heat to meet the
facilities heating needs or should there be separate sources of heat
designed especially for the services where they are needed? Answers to
these questions require considerable analysis of the heating needs and
the relative difficulty of maintaining the desired level of service in a
central facility. Nevertheless, the following is provided for general
guidance to the designer.
a) Choosing the type. Hot water heating systems are the most popular in
remote areas, probably because they are better understood than other
systems. With proper maintenance they can be as serviceable as other
choices. The primary disadvantage of a hot water heating system is its
potential for damaging piping systems during facility freeze-ups. Also,
hot water systems cannot provide the high quality heat needed for saunas,
and the heat available for hot water dryers is marginal. Ethylene or
propylene glycol can be used with hot water. These fluids can prevent the
freezing problems with hot water but they are slightly less efficient
(10-20 percent) in heat exchange properties than water, require more
attention in handling and maintenance, and can be corrosive.
Inhibitors can be used to control corrosion but they tend to
break down at high temperatures and maintaining the proper concentration
becomes another chore for operators. One way to achieve the higher
quality heat for all services in a central facility and avoid damage due
to freezing is to use special organic fluids instead of water or glycols.
These systems operate on the same principle as hot water, but the fluids
can be fairly expensive and the plumbing system must be more elaborate to
handle higher temperatures. Sloppy installation of the plumbing system
can be difficult to repair, and faulty joints can leak hazardous fumes
into the central facility [4],
Steam has a relatively high capacity to carry heat; hence, a
steam heating system can readily meet all of the heating needs in a
central facility. The main disadvantages of a steam system are that
-------
11-23
people in remote areas are generally unfamiliar with the higher
temperatures and mechanics of steam, and the hot pressurized vapour is
more hazardous. This makes operation of the steam system more difficult
and results in higher maintenance costs and down time compared with hot
air or hot water systems. Pipe damage due to freezing is generally
limited to low points or restrictions in the piping system.
Hot air does not have the heat carrying capacity of water or
steam, but it can be used effectively for dryers and saunas if separate
heat sources are used and the furnace is close to the place where heat is
needed. Hot air furnaces can be used for building heat also, although
controlling building pressure becomes a problem, and ducting consumes
more space than the plumbing for hot water systems.
b) Single versus multiple heat sources. A single heat source (e.g., one
central boiler serving all heat needs) for a central facility offers
simplified maintenance requirements and reduced fire hazards compared
with several heat sources (e.g., separate heating vents for building
heat, hot water dryers and other services). Stand-by capability for a
single heat source can be partially achieved by providing complete spare
burners. Control systems for distributing heat from a single source are
more complex than individual control for each of several heat sources.
Multiple heat sources can be used to meet the specialized
heating needs in the central facility. They can serve as back-up sources
of building heat since all units are not apt to be out of operation at
one time. If multiple sources are selected, compatible equipment with
interchangeable parts should be used. This will reduce the need for a
large spare parts inventory and make maintenance easier.
11.2.7.4 Water conservation and reuse. Fresh water is extremely
difficult to obtain in many remote communities and/or complex treatment,
sueh as distillation, reverse osmosis, or freeze-thaw techniques, may be
required. In addition, energy costs to run treatment equipment and
provide hot water can be substantial. Hence, every effort should be made
to reduce total water use.
Where fresh water is scarce, or costly to provide, the designer
should consider ways to provide water based on quality needs. For
-------
11-24
example, one can provide high quality water for drinking water fountains,
watering points, showers and lavatories by using a small complex
treatment system. A less complex treatment scheme may be appropriate for
toilets and washing machines. Also, saline or brackish water may be
adequate for toilet flushing if it is readily available.
Recycled water may be used for washing machines and toilets to
conserve water [6], However, caution should be used because of the
difficulty of providing consistently good effluents from wastewater
treatment systems. In practice, physical-chemical systems are capable of
providing a fairly stable effluent suitable for reuse in toilets and
washing machines, if they are operated properly. Biological treatment
systems tend to produce erratic results and secondary effluent should not
be reused unless additional treatment, such as filtration, is provided.
Dissolved solids in recycled water further complicate the usefulness of
this water conservation technique.
In summary, water reuse involves costly and complex treatment
systems and equipment. Where they are not absolutely necessary, water
conservation and reuse practices which add to the operating and
maintenance cost of a central facility probably have limited value.
Water reuse is not recomended unless raw water is extremely scarce or it
is difficult to treat. It is usually more economical and simpler to use
to flow reduction techniques to reduce consumption [9],
11.2.7.5 Incineration. Incinerators have been installed in several
central facilities for the primary purpose of disposing of waste
treatment plant sludges, honeybucket wastes, and other solid wastes in a
sanitary manner. Incineration theoretically offers an "ultimate"
solution to the problem of organic waste disposal; therefore, environmental
and health effects from these wastes can be avoided. Recognizing that
incineration requires a substantial amount of fuel oil, and electrical input
to "burn" the relatively wet wastes, extensive efforts have been made to
capture waste heat for reuse in central facilities. Figure 11-7 illustrates
a typical incineration process used at several central facilities [7].
Figure 11-8 shows the relationship between fuel consumption and moisture
content of solid wastes during incineration. Clearly, significant fuel
-------
11-25
Vapor to atmosphere
Dry refuse and garbage from
Central facility
School
Homes
"Wet" wastes from
Home "honey buckets
School
Toilets
Process sludges
'Waste" heat used in
Building
Utihduct
Clothes dryers
Saunas
Ash to land disbosal
Combustion gases and heat
™
Co. for Wastewater treatment
Secondary burner
for pollution control
Fuel oil and electrical inputs
FIGURE 11-7. SCHEMATIC OF INCINERATION PROCESS
Incineration has been designed here to be integral with
sewage and solid waste disposal, and building heating.
t
o
Q.
E
12
OT
C
O
o
0
0
Solid waste
moisture content
FIGURE 11-8.
RELATIONSHIP BETWEEN FUEL CONSUMPTION
AND MOISTURE CONTENT OF SOLID WASTE
DURING INCINERATION
-------
11-26
savings can be realized by dewatering high water content solid wastes.
An optimum moisture content can be determined by comparing the cost of
removing the moisture to the corresponding cost of incineration. This
optimum moisture content usually falls in the range of 25 to 40 percent.
Little work has been done to establish good design criteria for
incinerators in central facilities. The following information is based
on limited data [7]: a heat recovery system performed at 25 percent
efficiency (ability to achieve 50 percent recovery was calculated by
making minor equipment modifications); the heat content (thermal value)
of dewatered black water sludge ranged between 2481 calories/gram and
3808 calories/gram, based on four samples analysed; and, about one litre
of fuel oil was required to "burn" 15 L of sludge.
In spite of the environmental and health benefits, incinerators
have not proved very successful in central facilities. They are costly
to operate and controls are much too complex for the semi-skilled
operators in most small communities. On the other hand, for remote
industrial camps where environmental concerns are great and costs of
operation and maintenance are not so critical as for community central
facilities, incineration offers excellent treatment for combustible solid
waste and sludges. Section 13 provides additional information on
incineration.
11.2.8 Fire protection
Conventional fire protection systems are often inappropriate
for central facilities in remote communities. Unless a fire is
controlled within seconds or minutes after it starts, there is little
that can be done. Partial measures that can be helpful are: smoke
detectors, sprinkler heads or Halon systems for critical fire hazard
areas, accessible and clearly marked, and a liberal number of
hand-operated fire extinguishers.
Loud sirens or alarms can be used to alert the entire community
to fire problems.
Puchtler et al [4] made the following conclusion on fire
protection for central facilities:
-------
11-27
"Providing full fire protection for public facilities in rural
Alaska is unusually difficult and expensive. However, since
fire is a major threat to facilities in cold climate regions,
a decision not to provide this protection requires careful
consideration of resources available for replacement. Insurance
is generally not available exeept at very high premiums."
The ADEC has concluded that the level of fire protection
required by fire codes designed for larger communities in warmer climates
is not practical in the North. Its approach has been to provide only
that level of protection which is convenient. For example, water storage
tanks designed to meet the routine water supply needs for the central
facility can be used to supply sprinklers. While this may not protect
the entire facility according to fire codes, it makes the water that is
stored available for fire suppression at least until the water is gone.
Section 12 provides additional detailed information on fire protection
for utilities in the cold climate regions.
11.2.9 Construction techniques
In addition to choosing the method of construction, the
designer must consider whether to use preassembled modular units,
prefabricated sections or precut material ready for assembly at the job
site, or to "stick build" the facility on-site. Puohtler et al [4]
concluded:
"There is no single best method of constructing water-related
utility facilities in rural Alaska. Local conditions,
accessibility, etc., are so varied that a limited number of
standard designs could not be expected to effectively meet the
wide range of conditions."
The three basic options must be thoroughly analysed in relation to each
specific project.
11.2.9.1 Modular. Since skilled labor in remote communities is
generally unavailable, there are apparent advantages to using prebuilt
component modular construction, particularly for the relatively complex
systems often found in central facilities.
-------
11-28
Among these advantages are [7]:
1) components can be built more cheaply in the South where
equipment can be installed and where preassembled modular
units can be tested prior to shipment north, and
2) modular units can be more economically "mass" produced.
The conceptual design for an environmental service module by
Brown et al [1] stressed the importance of complete factory preassembly,
testing, and debugging of modular facilities prior to shipment and
installation at the site. This is confirmed by the U.S. Environmental
Protection Agency which found, in its limited experience, that modular
construction was not very successful, due in large part to inadequate
testing of component systems prior to shipment to the field [4],
Another major consideration associated with modular
construction is the tendency to compact the equipment and service areas
in the modules to facilitate shipping and reduce structure costs. As
stressed earlier, adequate space and accessibility to perform routine main-
tenance and equipment overhaul are essential, and crowded user space will
discourage use of even the most needed services in the central facility.
11.2.9.2 Prefabrication/precut. Prefabricated buildings and component
pieces of equipment have frequently been used in remote construction with
good results. Advantages, compared with modular construction, include
ease of shipment and minimum wasted space (crowded conditions and
inaccessibility can be avoided), some flexibility to make minor changes
to meet field conditions, and operators have an opportunity to become
familiar with the central facility as it is being constructed. Compared
with "stick-built" construction, assembly can be facilitated, fewer
skilled labourers are needed at the job site to assemble complex systems,
and there is less waste of materials. Preeut construction is similar to
the prefabrication technique and shares many of the same advantages and
disadvantages except that there are more "pieces" to assemble.
11.2.9.3 On-site fabrication. The ADEC has had satisfactory experience
with conventional wood frame construction. The main advantages are
simplicity of construction and ability to use local labour. In addition,
-------
11-29
the operators selected for the facility can participate fully in the
construction from the ground up. This helps them to better understand
how the facility operates and will facilitate operation and maintenance
functions. This technique offers the most flexibility to modify designs
to meet field conditions. On the other hand, complete on-site
construction can take longer and there will be more waste of materials
than with the other techniques.
11.1.10 Cost factors
Table 11-4 shows construction and operating costs for three
central facilities in Alaska. They represent facilities with minimum,
average, and extensive degrees of complexity and levels of service,
respectively.
TABLE 11-4. CONSTRUCTION AND OPERATING COSTS FOR THREE CENTRAL FACILITIES
Community
Council , Ak
Pitkas Point, Ak
Nulato , Ak
Population
53
85
330
Year
Completed
1978
1976
1976
Capital
Construction
Cost
118 000
350 000
860 000
Annual
Operating
Budget 1977*
20 000**
60 400
85 700
* Does not include amortization
** Estimated
The Council facility consists of a simple watering point and
three outhouses located conveniently for the village. The higher than usual
construction costs can be attributed to the installation of a windmill to
provide electrical power. It is backed up with a small fuel oil-fired
generator. The well is about 65 feet deep and has no treatment other than
provision for disinfection with chlorine. The village selected this minimum
level of service because this was all they felt they could afford to
operate.
The Piktas point central facility is considered to be of average
complexity. It provides a watering point, secondary sewage treatment,
showers, washers, dryers and saunas, and also water and sewer service to a
school. It was designed for simple operation, has several redundant
-------
11-30
features to prevent freeze-ups, and was constructed using the construction
management technique.
Conventional competitive bidding was used for construction of the
Nulato facility. It is a very complex system electrically and mechanically.
A high level of service is provided, including washers, dryers, saunas,
tertiary sewage treatment, complex water supply treatment, sewer and water
service to a school, watering point showers, and incinerator for solid waste
and honeybucket waste disposal.
Due primarily to the fact that water supply and wastewater
treatment requirements vary so much among the central facilities, dependable
cost factors for estimating purposes cannot be established. The cost
factors given in Section 2 may be used for general guidance, with special
consideration for specific water supply requirements and wastewater
treatment and disposal needs.
11.3 Remote Camps
11.3.1 History
Remote camps in the far North were used primarily to support
military activities until the early 1960's. These camps were used for
the military's DEW Line stations spaced across the top of North America,
and for oil and gas exploration activities in the northwestern corner of
Alaska. During the 1960's, private industry used remote camps in their
search for oil and gas in the North. The early camps had few amenities
for the workers and living conditions were crowded and often unsanitary.
They served up to about 50 people.
With the discovery of commercial quantities of oil and gas at
Prudhoe Bay in 1968, exploration activities virtually exploded. During
the summer of 1969, a comprehensive survey of 35 active camps and 30
inactive sites on the north slope was conducted [12]. The survey found
crowded living conditions, but generally good dining facilities.
Twenty-three camps used electric heat and all had some form of
pressurized water system. Sewage was almost exclusively dumped on the
ground or into shallow pits chipped out of the permafrost. Garbage was
generally dumped indiscriminately on the ground or into water bodies.
-------
11-31
For all camps, the average consumption of water on a per person
basis was estimated at 210 L/day. Eighteen sources of water were from
rivers and seventeen were from tundra lakes. Most of the camps consisted
of prebuilt modules which were transportable by Lockheed Hercules aircraft;
a few were built on-site.
Due to concern by government, labour unions and environmental
groups, industry has greatly improved remote camps and minimized their
impact on the environment. Housing is comfortable; dining facilities are
excellent; recreational facilities are provided; water is safe to drink;
various types of package systems are available to treat sewage; and
combustible garbage and sludges are incinerated prior to controlled land
disposal. Recent camps have housed from 10 to over 1500 persons.
11.3.2 Facility description
Present day camps in the far North are generally quite similar
in basic design and configuration. For mobile camps, geophysical crews
(population 20 - 30) use prebuilt trailer modules on skids or tracks.
The trailers each serve a specific purpose, including housing, dining,
clothes washing/laundry, office, equipment/supply, water supply, and
waste treatment. These trailers are particularly rugged and relatively
small in size (approximately 2.7 m x 2.7 m x 6.8 m).
Semi-permanent camp configurations and facilities depend
primarily on the number of people served. Modular trailer units can be
combined with relative ease to meet specific needs. In the larger camps,
recreational facilities are added to increase worker morale. Typical
layouts for mobile camps and semi-permanent camps are shown in Figures
11-9, 11-10, 11-11. Permanent base camps to serve between 150 and 300
people have been constructed on-site, and by assembling complete
prefabricated modules transported to the site by barge and large crawler
tractors. Figure 11-9 shows one of these facilities located at Prudhoe
Bay in Alaska.
A large majority of remote camps in cold climates are
associated with the extraction and transportation to market of oil and
gas reserves. Table 11-5 shows the types of petroleum industry related
camps, populations served, and duration.
-------
11-32
FIGURE 11-9. ROAD/PIPELINE CONSTRUCTION CAMP
FIGURE 11-10. DRILLING RIG CAMP
-------
11-33
Access road
Sewage treatmen
Warehouse
Warehouse
Road to airstrip
Valves and fittings enclose in insulated
box with removable top I I
5 Day raw sewage 30 mil liner
Camp fuel supply 50,000 L diesel
IIMIT i Sewage treatment
^y : t. Power plant
' I/I 56 Man housing (typical)
-52 Man hous
52 Man housing (typical)
Shop
Shop
Butler shop I 1
Butler shopf~]
Shop [^
Shop | J
age lift station
•ed)
^-Office
First aid
Laundry
Recreation hall
Hydran
56 Man housing (typical)
Equipment and material storage area
56 Man housing (typical)
52 Man housing (typical)
S — Sewer
W —Water
F — Fuel oil
250 000 L diesel emergency fuel supply
900 Corrugated mela! pipe
utihdor 14 guage
100 Sewage line with 50
nsulation field fit as required
100 Waterlme with
50 insulation
General notes
Indoors A Sanitary sewers all Sch 40 rigid P V C
B Fuel oil all sizes black iron Sch 40 socket weld
C Treated water all sizes copper
Outdoors A Sanitary sewers all sizes Sch 40 rigid PVC
pre-msulated with 50 urethane foam with heat tracing
B Fuel oil as noted for indoors
C Treated water all sizes pre-insulated with
50 urethane foam and with heat tracing
Removable top
')0 Fuel oil
100 x 100 x 900 Wood
sleeper at 1200 centres .' '.
Road Crossing
Section A-A
Handle
Lag bolts
Gravel pad ';•'.' '.'-.'.'
Original ground level ' •
Alternative Utilidor Designs
Section B-B
n(o>(5)
Alternative
Walkway Designs
FIGURE 11-11. LAYOUT AND UTILITIES FOR A PIPELINE CONSTRUCTION CAMP
-------
11-34
11-5. REMOTE CAMP SIZES AND DURATIONS
Type of Camp Population Camp Duration
Oilfield
Exploratory 3-5 2-3 days
Geological 20-30 3-7 days (winter)
Development
Drilling 50 30 - 90 days
Service 50 - 100 Varies
Production
Base 150 - 300 20 years
Pipeline
Construction
Road 200 - 300 3-9 months
Pipeline 600 - 1000 3-9 months
Pump Station O&M 15 20 years
11.4 References
1. Brown, C.K., et al, "Conceptual Design of an Environmental Service
Module", Report No. 75-01 for Defense and Civil Institute of
Environmental Medicine. Ontario Research Foundation, July 1975.
2. Dowl Engineers, "Design Narrative for Pitkas Point Village Safe Water
Facility", for the Alaska Department of Environmental Conservation,
Juneau, Alaska, 1975.
3. Arctic Environmental Engineers, "Conceptual Design for Tanana, Alaska
Facility", for the Alaska Department of Environmental Conservation,
Juneau, Alaska, 1978.
4. Puchtler, B. et al, "Water-Related Utilities for Small Communities in
Rural Alaska". Report No. EPA-600/3-76-104 (Ecological Research
Series), U.S. Environmental Protection Agency, Corvallis, Oregon,
1976.
5. Cameron, J.J. and B. Armstrong, "Water and Energy: Conservation
Alternatives for the North", Presented at Symposium on Utilities
Delivery in Northern Regions, March 19, 20, 21, 1979, Edmonton,
Alberta, Environmental Protection Service, Ottawa, Ontario, (in
preparation).
-------
11-35
6. Reid, Barry H., "Some Technical Aspects of the Alaska Village
Demonstration Projects", IN: Utilities Delivery in Arctic Regions,
March 16, 17, 18, 1976, Edmonton, Alberta, Environmental
Protection Service Report, EPS 3-WP-77-1, pp. 391-438, Ottawa,
Ontario, 1977.
7. Reid, Barry H. "Alaska Village Demonstration Projects: First Generation
of Integrated Utilities for Remote Communities". Working Paper No.
22, U.S. Environmental Protection Agency. Arctic Environmental
Research Laboratory, College, Alaska, 1973.
8. Minuse Systems, Inc., "A New Way to Reduce Household Water Use by
30%", Minuse Systems, Inc., 206 N. Man, Suite 300, Jackson, Calif.
9. Schatzbert, P. et al, "Energy Conservation Through Water Resource
Management - A Reduced Flow Bathing Shower", Second National
Conference on Water Reuse: Water's Interface with Energy, Air and
Solids, Chicago, May 4-8, 1975.
10. Bailey, J.R. et al, "A Study of Flow Reduction and Treatment of
Waste Water from Households". Water Pollution Control Research
Series 11050 FKE, Dept. of Health, Education and Welfare,
Washington, D.C., 1969.
11. Aulenback, D.B. et al, "Treatment of Laundromat Wastes", Report No.
EPA-R2-73-108 (Environmental Protection Technology Series), U.S.
Environmental Protection Agency, Washington, D.C., 1973.
12. Alaska Department of Health and Welfare, Federal Water Pollution
Control Administration, Arctic Health Center, "The Influence of Oil
and Exploration and Development of Environmental Health and QualityM
on the Alaska North Slope", Fairbanks, Alaska, December 1969.
11.5 Bibliography
Anon, "Waste Disposal Systems for Polar Camps". Technical Note
N-377, U.S. Naval Civil Engineering Laboratory, Port Hueneme, Calif.,
November 1959.
Anon, "Review of Polar Camp Sanitation Problems and Approach to
Development of Satisfactory Equipment for a Polar Region 100 Man
Camp". Technical Note N-032, U.S. Naval Civil Engineering
Laboratory, Port Hueneme, Calif., August 1952.
Given P.W. and H.G. Chambers, "Workcamp Sewage Disposal, Washcar -
Incinerator Complex, Ft. Simpson, NWT", IN: Some Problems of
Solid and Liquid Waste Disposal in the Northern Environment,
J.W. Slupsky [ed], Environmental Protection Service, Northwest
Region, Edmonton, Alberta, EPS-4-NW-76-2, pp. 1-42, 1976.
-------
11-36
Mecklinger, Sheldon, "Servicing of Arctic Work Camps". Department
of Civil Engineering, University of Toronto, Toronto, Canada,
April 1977.
Nehlsen, W.R., "A Development Program for Polar Camp Sanitation",
Technical Note 476, Armed Forces Technical Information Agency,
U.S. Naval Civil Engineering laboratory, Port Hueneme, Calif.,
December 1962.
Sargent, J.W. and J.W. Scribner, "Village Safe Water Project in
Alaska - Case Studies". Alaska Department of Environmental
Conservation, March 1976.
Sherwood, G.E., "Specifications for a 25-Man Pioneer Polar Camp".
Technical Note N500, U.S. Naval Civil Engineering Laboratory,
Port Hueneme, Calif., 1963.
U.S. Defense Documentation Center, "Temporary Polar Camp Concept and
Design Criteria". Technical Note N-436, Virgina, March, 1964.
U.S. Environmental Protection Agency, "Alaska Village Demonstration
Projects". Report to the Congress, Washington, D.C., July
1973.
U.S. Naval Civil Engineering Laboratory, "A Temporary Polar Camp".
Technical Note R 288, Port Hueneme, Calif., March 1964.
U.S. Naval Civil Engineering Laboratory, "Self Contained Sanitation
Systems for 2 to 15 Man Polar Facilities". Technical Report
R759, Port Hueneme, Calif, March 1972.
-------
SECTION 12
FIRE PROTECTION
Index
12 FIRE PROTECTION 12-1
12.1 General 12-1
12.2 Administration of Fire Protection Standards 12-1
12.3 Codes and Guidelines 12-2
12.4 Fire Prevention Criteria 12-2
12.4.1 General 12-2
12.4.2 Water supply fire protection requirements 12-3
12.5 Equipment 12-3
12.5.1 Trucks 12-3
12.5.2 Other methods 12-7
12.6 Community Fire Alarm Systems 12-8
12.6.1 General system description 12-8
12.6.2 System operation 12-9
12.6.3 System components 12-10
12.6.4 Alternate system design 12-12
12.6.5 Cost 12-13
-------
List of Figures
Figure Page
12-1 Graphic Annunciator Panel Detail 12-11
List of Tables
Table Page
12-1 Fire Protection Guidelines for Water Supply 12-4
-------
12-1
12 FIRE PROTECTION
12.1 General
Fire prevention, fire alarm and warning systems, and methods of
combatting fire in isolated northern communities present unique problems
that cannot be practically resolved by superimposing southern fire codes
and prevention standards.
The high cost of construction; the harsh climatic conditions
(very low ambient temperatures, generally extreme winds, drifting and
blowing snow); low population densities (most communities under 1000 in
population, almost all with volunteer fire departments); the very long
heating season; the dryness of materials and air; the generally poor
community infrastructures, i.e., rough gravel roads, no piped water in
most communities, little or no telephone service, are all factors which
make it difficult to guard against and fight fires in cold regions.
The proposed design guidelines for fire protection given in this
section are the result of experience and methods developed in the
Northwest Territories, Canada, since 1970. Techniques and methods used
in Alaska and Greenland are also noted.
12.2 Administration of Fire Prevention Standards
The following is a list of the governing authorities for fire
prevention standards. In other northern regions or jurisdictions, local
regulatory authorities should be consulted.
LOCATION ACT (If applicable) AUTHORITY
Northwest Fire Prevention N.W.T. Fire
Territories, Ordinance Marshal, Government
Canada of the N.W.T.,
Yellowknife, N.W.T.,
Yukon Territory, Yukon Fire Marshal,
Canada Government of the
Yukon, Whitehorse,
Yukon
Alaska, State Fire
U.S. Marshal's Office,
Dept. of Public
Safety, Juneau,
Alaska 99811
-------
12-2
12.3 Codes and Guidelines
Codes with respect to building spacing and water requirements
for fire protection purposes vary with the location and governing
authorities.
The main codes in use in temperate climates are:
- National Board of Fire Underwriters,
- National Fire Code,
- Uniform Fire Code, Insurance Advisory Organization,
- National Building Code.
Some of the guidelines are not practical or applicable for
small northern communities and must be constantly adapted or altered to
meet specific conditions under approval of the authority having
jurisdiction.
Two sets of guidelines for water flow and storage requirements
are given in Appendix I. Appendix I.I gives a draft standard for water
supplies for small rural isolated communities (such as Indian reserves
throughout the various provinces of Canada) prepared by the Canadian
Dominion Fire Commissioner's office. Appendix 1.2 gives a guideline for
water works design, prepared by the Province of Ontario.
12.4 Fire Prevention Criteria
12.4.1 General
Fire prevention criteria, such as building spacing, building
location distances from roadways, access to buildings, fire escapes,
building occupancy, requirements for sprinklers and smoke detectors and
requirements for water distribution system flow and storage capacity in
the North, are generally adopted from existing codes, such as the
Building Codes and Fire Codes referred to previously, and as formulated
by the authority having jurisdiction.
Although the purpose of fire protection systems is universal,
the capability of water supply and distribution systems to meet the rigid
requirements of codes cannot always be provided in small rural communi-
ties. Economic and physical constraints have dictated the limits of
water supply and distribution systems, which in turn may prohibit meeting
-------
12-3
present codes and guidelines for fire protection. In such cases, the best
practicable fire protection system developed often employs alternatives to
water for fighting fires. Also, when a fire is extinguished with water at
below 0°C temperatures the resulting iee can do more damage to the
building than the fire.
There are numerous communities in both Alaska and northern
Canada where there are no funds for necessary infrastructures, such as all
weather roads to allow a fire truck to operate, let alone funding for the
purchase of a fire truek. Despite the above, assuming communities are to
be viable entities and fire protection treated seriously, the reoommenda-
ations made in this section are considered to be the achievable, practical,
minimum level to be strived for.
12.4.2 Water supply fire protection requirements
General assumptions used when determining water supply values
required for fire fighting are as follows:
- The water supply fire protection requirements are considered
concurrently with the total community utility development
planning. For instance, an indoor swimming pool can be also
used to satisfy community fire storage capacity.
- Population is based on a 20-year forecast.
- Each community has its own unique set of characteristies.
Population levels used to determine the standard of fire
protection which should be provided will depend on a detailed
economic analysis. The choice between a trucked or small
piped or large piped system will be based on an economic
evaluation over the 20-year forecast period.
The guidelines for water supplies in northern communities
recommended in Table 12-1 are based on Appendix I and experience gained
in Alaska and northern Canada.
12.5 Equipment
12.5.1 Trucks
Communities of less than 150 in population. The water truck can be
used as the fire truck. See Section 6 for description and cost.
-------
TABLE 12-1. FIRE PROTECTION GUIDELINES FOR WATER SUPPLY
TYPE OF
SERVICE
COMMUNITY CHARACTERISTICS
FIRE PROTECTION WATER DELIVERY
SYSTEM REQUIREMENTS
Trucked
Water
Delivery
- Trucked water supply only.
- Bldg. spacing 12 m (minimum)
- Community fire alarm system
in operation.
- Volunteer fire brigade.
Community water point must be capable
of delivering a minimum of 450 litres/
minute.
Fire truck/pumper is left with full
tank in heated garage.
Domestic water truck is left full in
heated garage as back up.
Small
Diameter
Piped System
- Small diameter piped system (flow
based on consumption requirements
only).
- Hydrants can be provided to
allow limited access to water
for fire fighting.
- Building spacing 12 m (minimum).
- Community fire alarm system in
operation.
- Volunteer fire brigade.
Water storage tank for fire fighting
purposes to be supplied and located in
central or strategic location in the
community. Size of storage capacity to
be based on the formula described in
Appendix G.
Piping capacity of a minimum of 2500
litres/minute either from a truck mounted
pump or insitu pump that will deliver water
directly from the storage tank through an
appropriate hose delivery system capable of
servicing a 150 m radius from the storage
tank.
A truck water point from the storage tank
location will be provided capable of delivering
700 litres/minute for refilling the fire
truck to combat fires in those areas not
capable of being reached directly by hose.
All available fire and water delivery trucks
to be kept in heated garages at all times.
N3
i
-------
TABLE 12-1. (CONT'D)
Large
Diameter
Piped Core
System
- Large diameter core system with
hydrants.
- Remainder of community serviced
by small diameter piped system
with no fire flow provisions.
- Building spacing core area with
hydrant coverage 3 m (minimum).
- Building spacing elsewhere 12 m
(minimum).
- Community fire alarm system in
operation.
- Volunteer fire brigade.
Water storage tank for fire fighting
purposes to be supplied and located in the
community. Size of storage capacity to
be based on the formula described in
Appendix G.
Pumping capacity of a minimum of 2500
litres/minute either from a truck mounted
pump or insitu pump that will deliver
water directly from the storage tank
through an appropriate hose delivery
system capable of servicing a 150 m
radius from the storage tank.
All hydrants on large diameter core system
to be capable of providing 2500 litres/minute
through either an in place pumping system
or truck mounted pumps. Each hydrant
should service a circular area with a
radius of 70 m.
A truck water point from the storage tank
location will be provided capable of
providing 700 litres per minute for refilling
of fire truck to combat fires in those
areas not capable of being reached directly
by hose.
NJ
i
Ul
Large Diameter
Piped System
Throughout
Community
- Larger diameter piped system,
i.e. minimum pipe size 150 mm or
greater. All lines with hydrants
in place every 70 m or less and
capable of producing required
Storage tank capacity as per formula
given in Appendix G.
Water fire flow capacity as
outlined in Appendix G.
-------
TABLE 12-1. (CONT'D)
(cont1d)
- Building spacing minimum 3 m or
as specified by the appropriate
authority.
- Community fire alarm system in
operation.
- Paid fire chief.
- Volunteer fire brigade.
- Fire flow capacity can be provided
through in place pumping system or truck
pump.
Isi
I
-------
12-7
Houses should be equipped with cartridge fire extinguishers and
detectors.
Communities with no piped water.
A 4500-L capacity truck should be provided with a 2800 L/minute
pump output rating.
Truok cost including assessories $ 50 000
Fireball cost (one bay) $100 OOP ($500/m2)
Communities with small diameter piped water, no hydrants.
Same as above.
Communities with large diameter piped water, with hydrants.
A 2273-L capacity truck should be provided with a 3800 L/minute
pump output rating, to be used in conjunction with hydrant or
storage tank facility.
Truck cost including accessories $ 60 000
Fireball cost (one bay) $100 OOP ($500/m2)
12.5.2 Other methods
Foam equipment, either cylinder or truck-mounted, is not
recommended for northern use during low ambient temperatures of -25°C
or eolder. Such cold temperatures do not allow the aspirator to mix
properly with the foam; a "soup" is produced.
Dry chemical. Large 350-lb ABC dry chemical extinguishers have
been used in most communities in the Northwest Territories, Canada, with
satisfactory results when properly utilized. Because of the large size
of the unit, it is difficult to move in a hurry and should really be
incorporated in a truck kept in a heated garage and ready to go. In
those communities where it is best utilized, the unit is placed on a
stand ready to be rolled onto a half ton truck or dump truck and taken to
the fire. The unit must be serviced after each use.
Halon gas is useful in high hazard buildings and where
electrical or mechanical equipment could be destroyed by wet system
malfunction. This system is expensive and is not applicable in all
buildings at this time.
-------
12-8
Fire extinguishers for house use are recommended and should be
the cartridge dry chemical ABC type. These have proven the most reliable
and most economical to maintain. Commercially available units of various
sizes have fusible links which automatically discharge when exposed to
fire.
Smoke detectors are usually actived by sensing the products of
combusiton. Such units may be installed in kitchens or next to furnaces.
They are becoming more prevalent and in some cases are mandatory. All
public government buildings and staff houses in the Northwest Territories,
for instance, must have a permanently wired smoke or heat detector devices.
There are anumber of smoke detectors on the market, and as long
as the unit has been approved by the Canadian Standards Association (CSA)
and Underwriters' Laboratory (ULC) it will do a satisfactory job when
used in accordance with the manufacturer's direections.
12.6 Community Fire Alarm Systems
Community fire alarm systems in the North, while highly desired
by the communities, have been an extreme source of frustration for users,
maintainers and designers over the years. A system is a failure unless
it works when it is needed and works every time. Considering the factors
of climate, lack of technically competent tradesment, constant turnover in
personnel, et., a perfect operational record is a monumental achievement
for a designer who must also produce an economical system.
The community fire alarm systems described in this section were
delveoped by Mr. Ray Stoodley of the Government of the Northwest
Territories, based on previous experience and personal knowledge of
northern conditions gaind over the past two decades as an electrical
contractor, and in his present position with the Government of the
Northwest Territories.
It is essential to involve the local people in the design and
installation process to the point where they see the merit of regular
checks and any preventative maintenance required.
12.6.1 General system description
The previously adopted southern systems used standard drop zone
annunciator panels (8-12 zones) and 1 hp single-phase repulsion induction
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12-9
motorized sirens. The present state-of-the-art in the North employs
supervised multi-zone annunciator solid state equipment and leased
telephone company cable pairs for call box signal and multi-siren
activation.
12.6.2 System operation
Call boxes are located strategically throughout the community to
provide maximum coverage. In the event of a fire the call box button is
pushed, which sets off the sirens and thus marshalls the volunteer fire-
fighters at the fire hall. At the same time, a graphic readout annuncia-
tor panel is activated at the fire hall. In other words, a red light on
a large scale map of the community shows the location of the tripped pull
box. The firemen note the location and proceed to the fire. The sirens
continue until the annunciator panel alarm light is acknowledged by the
arriving firemen. If in the interim another call box has been tripped,
it will light up after the first light has been acknowledged and again
set off the alarm. The system is constantly supervising itself, which
means that a short in a cable pair or a severed line will sound a trouble
alarm altering the appropriate staff to the problem.
A test button is provided, which by-passes the timing circuit
and allows control of the siren for up to two minutes, at the discretion
of the operator. (Two minutes is the maximum recommended time to operate
these sirens.)
The system can aoeept signals such as low temperature, intrusion
or any other dry contact, by simply adding the required annunciation and
audible devices separately from the siren circuit. This allows the ,
system to be integrated with other critical community utilities suoh as
water supply, etc., since in most small communities the diesel-generated
power is unreliable. Under and over voltage protection is provided by a
voltage limiter, whieh will disconnect the supply voltage when it drops
to 105 volts AC and pick up again at 120 volts AC. A time delay of two
to five seconds is fitted to prevent relay chatter. Disconnection of the
system is preferred to a previously designed battery powered system which
used AC power for charging-up as required. Even with battery standby
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12-10
provision, no power would be available during a power outage for siren
operation; therefore, standby battery power is really superfluous. The
system is fitted with a program clock device to sound a daily curfew for
a predetermined time (constant blast of approximately 20 seconds). This
also provides daily testing of the sirens.
12.6.3 System components
Sirens may be electronic or rotary multidirectional. Electronic
sirens are used in smaller settlements with populations of 350 or less
and restricted to a maximum community distance in any direction of 3 km.
Characteristies of this type are:
- low capital costs ($130 each);
- minimum or no maintenance;
- coverage of 110 DB @ 3 m in still air;
- uses 120 volt AC;
- lightweight (one man can change a defective unit);
- daily testing required to prevent heavy ice build-up.
Rotary multidirectional sirens are more cost-effective for
larger communities. In general, where adequate coverage for a community
requires 12 or more electronic sirens then one or two rotary
multidirectional sirens are used.
Characteristics of this system are:
- 5 hp three-phase, 208 volts, high horse power required to
ensure any ice build-up is sheared away on start-up;
- thermistor sensors in motor winding wired with normal motor
overload circuit to prevent burn out;
- life expectancy of 20 years;
- coverage of 115 DB @ 30 m with an effective sound range in
still air of 1050 m.
- cost of $2500 each.
Leased telephone cable pairs are preferred to individually
installed and maintained cable plants for signal circuits because of
lower capital and maintenance costs.
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12-11
Graphic readout panels in the fire halls display all station
call boxes with indicating lamps superimposed on a large-scale plasticized
map of the community (see Figure 12-1). Also included are acknowledge,
reset and trouble lights, and test buttons. The panel must be tailor
made but eliminates any confusion as to where to go in situations where
firefighters are made up of people with different languages.
FIGURE 12-1. GRAPHIC ANNUNCIATOR
PANEL DETAIL
Station indicating lamp call box assembly. Based on
experience and past problems, the best call box for northern use is a
CEMA-3 enclosure of special design to prevent entry of rain, sleet or
driving snow. On opening the enclosure door, the caller merely pushes
the red button for a moment. Behind the facia holding this push button
is a pair of line fuses. One spare fuse provides protection for the
station indicating lamp circuit. The indicating lamp used is rated at 60
watts, 8000 hours for long life and low maintenance. All related wiring
between the indicating lamp higher up the utility pole and the call box
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12-12
is eontained in a rigid PVC conduit. The rigid PVC results in a good,
water-tight, noncorrosive and very easy field installation. Each call
box is grounded at the base of the PVC. Where permafrost or soil
conditions prevent the use of ground rods, a grounding mat buried a
minimum of 60 cm for a length of 16 m is used.
Solid state relay equipment operates at between 5 and 35 volts
DC and is capable of switching an AC load of up to 16 amperes. The relay
is completely sealed and has an expected life of 20 years. Unlike
previous designs, the solid state relays do not require matching relays
on call box circuits located up to 8 km away from the main control
system. Problems with end of line resistors or diodes are also
eliminated since the new configuration does not require these components.
Lightning surges and possible stray currents to call circuits are
prevented by the telephone company lightning arrestor equipment.
12.6.4 Alternate system design
A system has been installed and is operating in Cape Dorset
(population approximately 900) which is based on the use of a Bell Canada
type 700 "Code-A-Phone" device. This device replaces both the solid
state relay equipment and the graphic read-out panel. All other
components, i.e., call boxes, sirens, etc., remain the same. Using a
pre-coded number (e.g. 2222), any telephone in the community is able to
set off the fire sirens. At the same time, a prerecorded message will
ask in whatever language applicable, "Where is the fire?". The caller
can then give the name and location. The firemen responding would play
back the tape to ascertain the caller's identification and location.
ADVANTAGES: - very low installation cost (40% of a standard
system);
- assuming 80% telephone coverage, increased
safety factory by virtue of quicker alarm
activation;
- minimal maintenance;
- system will easily adapt to any number of
sirens.
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12-13
DISADVANTAGES: - possible false alarms;
- possible confusion when the caller tries to
tape the information;
- forgetting to reset the tape (although good
for 12 hours it would be desireable to have
the unit reset itself after each call has been
acknowledged);
- cannot easily be tied in to equipment for
other alarms, e.g., water flow, etc.
12.6.5 Cost
The average cost per signal circuit pair per month is $3.50.
Between 12-36 pairs will be needed, depending on the size of the
settlement. The average coverage per call box is one for every five
homes or 30 people. Major buildings and installations must be considered
separately. The installed cost of these systems is approximately
$1 000 per call station. This includes the cost of siren and annunciator
equipment.
The cable cost would be additional to the above figure and
varies considerably between the western and eastern territories.
Examples are Rankin Inlet, where the installed cable cost for 36 pairs
was $2 300 and Fort Resolute, where the cable cost for 26 pairs was
$8 300. Line pair rentals run approximately 50% lower in the east and
central, compared with the western territories.
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SECTION 13
SOLID WASTE MANAGEMENT
Index
13 SOLID WASTE MANAGEMENT 13-1
13.1 General 13-1
13.2 Municipal Solid Wastes 13-2
13.2.1 Quantity and composition of wastes 13-2
13.2.2 Household storage and collection 13-3
13.2.3 Disposal methods 13-7
13.3 Industrial and Special Solid Wastes 13-20
13.4 Human Wastes from Households and Establishments 13-21
13.4.1 Storage at the house and collection 13-22
13.4.2 Quantity and composition of human wastes 13-27
13.4.3 Disposal 13-27
13.4.4 Costs and Charges 13-30
13.5 References 13-32
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List of Figures
Figure Page
13-1 Garbage Collection 13-6
13-2 Garbage Barrels on Raised Wooden Platforms 13-6
13-3 A Poor Example of Garbage Storage at the Home 13-8
13-4 Garbage Cart and Stand 13-8
13-5 A Difficult Solid Waste Handling Problem 13-12
13-6 A Proper Garbage Dump Truck would Help Considerably 13-12
13-7 Attempt to Create a Dumping Slope on Flat Terrain (a) 13-13
13-8 Attempt to Create a Dumping Slope on Flat Terrain (b) 13-13
13-9 How would You Like This Job? 13-14
13-10 Disposal of Garbage and Honeybags at the Same Site.
This should not be done 13-15
13-11 Storage Tank Disposal on Garbage Dump 13-15
13-12 Typical Bucket Toilet 13-23
13-13 Manual Handling of Honeybags Stored in Drums in Front
of the House until Collection 13-24
13-14 Metal Buckets Used for Collection of Human Waste 13-25
13-15 Rear View of Honeybag Suction Vehicle 13-26
15-16 Disposal Station for Human Waste at Egedesminde,
Greenland 13-31
13-17 View of Inside of Disposal Station, Egedesminde,
Greenland 13-31
List of Tables
Table
13-1 Quantities of Solid Waste from Camps
13-2 Quantities of Solid Waste from Communities
13-3 Composition of Solid Wastes
13-4 Domestic Refuse Composition for a Typical Aretic
Community
13-5 Garbage Collection Costs
13-6 Characteristics of Human Waste (Honeybags)
13-7 Honeybag Collection Costs
13-2
13-3
13-4
13-4
13-19
13-28
13-30
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13-1
13 SOLID WASTE MANAGEMENT
13.1 General
Solid wastes are one of the most important visual parts of an
overall sanitation program for northern communities. Many priorities
must be met with limited funds by those charged with the responsibility
to provide for and improve social and environmental conditions in
these communities. Providing jobs, housing, heat, light, water and
sewage disposal have been given higher priority than solid waste
management in the past, but it has recently received greater attention.
Emerging legislation, research and pilot projects for solid waste
management are evidence of increasing concern.
For the purpose of this manual, solid wastes are divided into
three groups:
- municipal solid wastes: from households, commercial or
institutional establishments;
- industrial and special wastes;
- human wastes from households and establishments.
The disposal of sludges from water and wastewater treatment
plants is covered in Section 10. The disposal of human wastes without
water carriage occurs because of the lack of piped water and sewer
systems in many of the smaller communities. Because of the similarities
in the storage, collection and disposal of garbage/refuse and human
waste, the latter is discussed in this section, with reference made to
other sections where relevant.
The objectives of solid waste management, north or south, must
be to dispose of wastes without creating hazards, nuisances, or aesthetic
blights for people and for the environment, and to achieve this in the
most economical manner for a given situation. To achieve these
objectives, it is necessary that each component of the solid waste
management system, namely, storage in or at the house, collection and
treatment/disposal, is properly carried out. Reviews of northern
practices in solid waste management with recommendations for improvements
have been carried out by a number of agencies [1-8,19,30,33],
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13-2
13.2 Municipal Solid Wastes
Municipal solid wastes include all unwanted or discarded solid
or semi-solid material from households, commercial and institutional
establishments. While the type and quantity of wastes from these will be
similar to those in southern communities, there are special considera-
tions to be taken into account in northern communities. Most of the
'goods' consumed must be shipped from the South. This leads to greater
quantities of packaging material in the waste. The isolation and high
transportation costs make recycling of used machinery, mobile homes,
automobiles, etc., as scrap raw material uneconomical and increase the
quantities to be disposed of locally. Finally the combination of past
social customs, inadequate health and sanitation habits and education
make it difficult to implement effective solid waste management.
13.2.1 Quantity and composition of wastes
Data on refuse from work camps, military bases and airport
facilities, which in many aspects are similar to southern communities,
are shown in Table 13-1.
TABLE 13-1. QUANTITIES OF SOLID WASTE FROM CAMPS
Camp Quantities
Air Force Base [10] 2.3 kg/person/day
Pipeline Construction Camps [11] 2.7 kg/person/day
Alaska-Federal Facilities [5] 2.7 kg/person/day
Fort Greely [5,15] 6.1 kg/person/day
Recently Wardrop ^t al^ [37] reported that facilities such as
these in the Northwest Territories generated refuse at a rate of 2.7 to
4.4 kg/person/day. The Alaska Department of Environmental Conservation
(ADEC) uses a generation rate of 3.6 kg/person/day for design purposes.
Little information regarding the density of refuse from such
facilities is available. However, a recent survey at Alert, N.W.T., made
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13-3
by Wardrop et al [37] concluded that the refuse generated at this site
had a density of 91 kg/m3.
Table 13-2 tabulates orae recent information on solid waste
quantities for communities with little industrial activity.
TABLE 13-2. QUANTITIES OF SOLID WASTE FROM COMMUNITIES
Camp Quantities
Tuktoyaktuk, N.W.T. [9] 0.014 m3/person/day (0.5 ft3/person/day)
Alaska [5] 2.8 kg/person/day
(average of communities > 500) 0.015 m3/person day (0.54 fts/person/day)
Northern ONtario connumities [12] 0.005 ms/person/day (0.18 ft3/person/day)
For such communities, an average volume of about 0.005-1.015 m3
should be used for planning purposes. The lower figure would apply when
burning at the household or establishment is practised. Without special
compaction or burning the average density may be about 130 kg/m3 but
considerable variation must be expected. On a weight basis, therefore,
1.8 kg/person/day can be used for design purposes.
Tables 13-3 and 13-4 provide the only available information on
compostion of solid waste in residential communities. Table 13-3 reports
a survey of two northern communities, Juneau and Anchorage, and provides a
compparison with a southern community, Madison, Wisconsin, and the U.S.
national average. It should be noted that both Juneau and Anchorage are
larger, more temperate zone communities than many other norther communities.
Table 13-4, on the other hand, provides an estimate of domestic
refuse composition for typical northern communities which may be helpful in
small community design. This information is based on unpublished data
collected by W.L. Wardrop and Associates Ltd. personnel during visits to
several Arctic communities.
13.2.2 Household storage and collection
In the larger communities the practice of storage and collection
of waste does not differ substantially from the practices in southern
communities. In smaller northern communities garbage and refuse are
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13-4
TABLE 13-3. COMPOSITION OF SOLID WASTES
Classification
Percent of Total Sample
Food Waste
Paper Products
Plastics
Rubber and Leather
Textiles
Wood
Metals
Glass and Ceramics
Garden Waste
Inerts (dirt)
Totals
Juneau,
Alaska
15.2
45.8
4.0
1.3
3.0
0.6
12.5
17.1
—
0.4
99.9
Anchorage,
Alaska
15.2
43.7
4.1
0.9
2.1
1.2
10.0
14.5
6.5
1.7
99.0
Madison,
Wisconsin
15.3
42.4
1.8
—
1.6
1.1
6.7
10.1
13.8
7.2
100.0
U.S. National
Average
17.6
31.3
6.0
—
1.4
3.7
9.5
9.7
19.3
1.4
100.0
TABLE 13-4. DOMESTIC REFUSE COMPOSITION FOR A TYPICAL ARCTIC COMMUNITY
Component
Composition by Weight
Combustibles (wood, paper, etc.)
Metal
Organic Wastes
Moisture
50%
15%
15%
20%
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13-5
commonly stored at the house in readily available oil drums. They are
probably the only type of container capable of sustaining the abuse by
weather, people and animals. They are large enough to hold animal
carcasses and other bulky refuse and heavy enough not be be upset by wind
or dogs. Also, one can burn combustible waste in them for volume
reduction. This practice should be encouraged. They are, however,
difficult to lift manually onto the collection vehicle (Figure 13-1).
Mechanical lifts can be attached to the side of the collection truck to
avoid this problem. In some communities raised wooden platforms have
been constructed to hold drums for garbage and honey bags so that they
can be easily emptied (Figure 13-2). In many instances this attempt has
been a failure, either because the platforms were not rugged enough, or
they became an eyesore since they were covered much of the time with
spillage. This eventually caused them to be abandoned. In other
communities smaller metal or plastic pails are used. They are easier to
handle, but are blown over by wind or upset by dogs, do not hold bulky
waste, and burning cannot be practised. Plastic containers are also
brittle at low temperatures. In all containers garbage will freeze to
the walls, making it difficult to empty them in cold weather. A pilot
study program using paper sacks was carried out by Environment Canada in
two northern Canadian communities. The results were disappointing; the
project had to be abandoned soon after its start, since the local
population did not perceive it as an improvement over previously used
methods [29], In summary, there is much to recommend the continuation of
the use of the readily available oil drums for storage at the house, but
it also should be coupled with educational efforts to avoid the situa-
tions shown in Figure 13-3. Periodic cleaning and painting of drums is
recommended.
In many communities there is some organized collection of
garbage and refuse on a weekly or twice-weekly basis. Mandatory or
universal collection is currently required in more than 50% of Alaskan
communities greater than 500 people [5], In all but the very small
communities weekly collection, whether public or private, should be
required. Garbage and refuse collection should be separate from the
collection of bagged toilet waste, since the latter requires daily
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13-6
FIGURE 13-1. GARBAGE COLLECTION
FIGURE 13-2. GARBAGE BARRELS ON RAISED
WOODEN PLATFORMS
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13-7
frequency and a separate disposal site. Vehicles vary in sophistication
from the garbage packer truck as used in the south to tractor-drawn open
carts (Figure 13-4). Most vehicles are of the open type and lose garbage
within the community and along the road to the dump. This sets a bad
example to the people and negates any educational efforts for cleanup.
Enclosed or covered vehicles should be required with the appropriate
degree of sophistication depending on the size of the community.
Garbage crews should also be made responsible for general street
cleanup and maintenance, and thus set an example to the citizen. Without
this, the appearance of many northern communities suffers from the
indisoriminate disposal of garbage, refuse, vehicles and scrap items of
all sorts in yards, on roads and beaches. This becomes progressively
worse as the winter goes on, mercifully covered snow. Massive spring
cleanups occur in most communities. Community-wide cleanups should be a
general practice several times a year and their need particularly
impressed upon the young in school.
13.2.3 Disposal methods
Alternatives for disposal of solid wastes in northern communi-
ties and eamps include:
1) open dump/landfill;
2) modified landfill;
3) ocean disposal;
4) incineration;
5) milling and compaction;
6) recycling and reuse (haulback).
Currently the most often used method is the open dump, which in some
cases can be termed a modified landfill. Seventy-six percent of Alaskan
communities use a form of open dump/landfill method, 13% use ocean
disposal and 11% employ incineration (all of these are U.S. federal
facilities [5]). The open dump/landfill is also widely used in Canadian
communities. The advantages and disadvantages of each method are
discussed below.
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co
i
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13.2.3.1 Open dump/landfill. The main reasons for the use of the open
dump are its simplicity of operation, its low cost, and the lack of
suitable alternatives. The main arguments against its continued use are
the many instances of complete disregard of even the most simple techni-
ques of discrimination in the selection and operation of existing
disposal sites. These poor practices, which are avoidable, make it
difficult to convince regulatory authorities and the public to accept the
open dump/landfill.
Parameters for disposal site selection include: avoidance of
water pollution problems, avoidance of air pollution problems, feasibility
of construction and maintenance of access road, site topography and size,
availability of cover material, and wind exposure. The most important
site selection criterion is that it should be located outside the water-
shed of the water supply source to eliminate any possible pollution
effects. The site should be on high, dry ground to avoid drainage and
groundwater problems [27]. If there is a prevalent wind direction, the
site should be located down-wind from the community, so that unpleasant
odours or smoke from burning at the dump are directed away from the
settlement. The ground between the disposal site and the community must
allow for the construction and maintenance of a year-round access road.
The distance from the site to the nearest homes should be at least 1 km
where possible. When there is a choice between alternative sites, the
construction and maintenance costs for a multiple-use access road should
be considered against those for a single-purpose waste disposal site
access road.
A sloping site is preferable since it facilitates dumping and
spreading operations. On flat land a slope can be created through
deposition of waste and cover material, where available. The area for
the dump/landfill operation should be large enough to allow for 5-10
years or longer operation, particularly when the cost of the access road
is high. Usually land area is not a problem. A smaller area may be
prepared and fenced for current usage, with adjacent room for expansion
available. The fenced site should be large enough to allow for deposition
of garbage and refuse and a close-by storage of cover material. The cold
northern climate makes biological degradation of putrescible matter so
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13-10
slow that the value of occasionally covering the waste is really only in
preventing garbage and paper from being blown around the site, and in
reducing the danger of disease transmission through insects, birds and
animals. Periodic compacting and covering of the waste is, therefore,
recommended where at all economically possible. Availability of nearby
cover material is, therefore, important. In some cases, snow has been
used as a cover material. The requirement for fencing is based on
similar reasoning. It will confine the blowing of waste to the site and
may keep out larger land animals. It has also the psychological advantage
of creating the impression of an "engineered" operation. Where there is
a choice, a protected, less windy site will be preferable. The controlled
burning of combustible material at the disposal site serves the useful
purpose of volume reduction and odour control, but may create air pollu-
tion and smoke problems. In some areas it may also not be permitted.
The provision of space for dumping of large, discarded items
such as automobiles, machinery, demolition material, etc. must also be
considered. Where space allows, it is preferable to locate such an area
near the garbage dump. This eliminates the need for a separate road and
allows the periodic bulldozing and "compacting" of that area. Not
providing such a facility will encourage indiscriminate dumping. It is
also necessary to have available a tow truck or other vehicle capable of
loading, hauling and unloading inoperable vehicles and machinery.
If these simple guidelines of site selection and operation are
adhered to, the environmental effects of the open dump/landfill are
minimized. Under these circumstances, the advantages of cost and ease of
operation make it the most sensible method of waste disposal at the
present time. The site should be selected by experienced people with the
help of aerial photographs and inspection of alternative sites. It
should not be left up to the garbage crew to choose the site(s).
Reclamation of land from the ocean by the building of a berm off shore
and the filling in with solid waste, earth and rock are carried out in
Godthab, Greenland, and Pangnirtung, N.W.T. This may have application in
other areas where land is scarce.
Because of the different nature of the waste, bagged human
wastes should be disposed of separately from solid waste, as discussed
later (see Section 13.4.3).
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13-11
Figures 13-5 to 13-11 show some of the situations experienced at
existing disposal sites.
13.2.3.2 Modified landfill. The proper application of sanitary
landfill procedures is usually impossible in permafrost areas. The low
temperature does not permit the degradation of putrescible matter to
occur, but merely places the waste in cold storage. Excavation is
extremely difficult and may create difficulties through destruction of
the insulating layer. Earth cover material must often be transported
considerable distances to the disposal site and is therefore expensive.
Daily or even weekly covering becomes economically impossible. The small
size of most communities makes it seldom practical to keep a bulldozer on
the site continuously, as it is needed for other tasks in the community.
For these reasons sanitary landfill is generally not a practical method
of disposal in permafrost areas. In discontinuous permafrost areas, and
where cover material is available at reasonable cost and the size of the
operation allows the continuous presence of equipment, a form of land-
fill approaching the practices of sanitary landfill in southern areas is
a practical alternative. The comments on site selection and preparation
given earlier in the discussion of the open dump should be adhered to.
Articles by Straughn [13] and Cohen [14] provide further information.
Another form of the modified landfill is a trench method. In
communities which have piped service systems, tractor-mounted back-hoes
are normally available for systems maintenance. These can be used to dig
trenches at the solid waste disposal site, up to about 3 m deep. The
refuse is dumped into these trenches and, when nearly full, they are
covered with excavated material (about 1 m). New trenches ,are then dug.
This method can be used in permafrost areas, provided the machinery is
able to dig such trenches.
Another possible variation, not yet tried on a community scale
in northern regions, is composting [31] of garbage, kitchen wastes and
human waste either on an individual household basis or on a community
basis. Experience with municipal composting operations in Europe would
indicate that it is not likely to be economically feasible in most of the
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13-13
FIGURE 13-7.
ATTEMPT TO CREATE A DUMPING
SLOPE ON FLAT TERRAIN (a)
FIGURE 13-8.
ATTEMPT TO CREATE A DUMPING
SLOPE ON FLAT TERRAIN (b)
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13-14
FIGURE 13-9. HOW WOULD YOU LIKE THIS JOB?
FIGURE 13-10.
DISPOSAL OF GARBAGE AND HONEY
BAGS AT THE SAME SITE. THIS
SHOULD NOT BE DONE.
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13-15
FIGURE 13-11. STORAGE TANK DISPOSAL
ONTO GARBAGE DUMP
northern communities because of their small size and because of the
climate.
13.2.3.3 Ocean disposal. Many of the smaller communities on the ocean
dispose of their garbage and "honey bag" wastes by placing them on the
ice in the winter, relying on spring breakup to wash away the material
[5], The remoteness of the communities, the relatively small quantities
of waste involved and the vastness of the ocean make this practice
tolerable for small communities. Future legislation may prohibit this
practice.
13.2.3.4 Incineration. Incineration is a controlled process for
oxidizing combustible waste to carbon dioxide, water and ash. Normal
domestic garbage and refuse has an average heating value of about 11.6
megajoules/kg and thus can be considered a valuable fuel resource,
particularly in northern areas where fuel must be brought in at great
expense. Some years ago it was thought that incineration had great
potential for Alaskan communities and might replace the practice of open
dumps [5], However, the experience of the few installations that have
been built at federal facilities [5,10] and in parts of the Alaska
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13-16
Village Demonstration Project (AVDP) has been that incineration of solid
wastes is not economically feasible for communities because of high
operative and maintenance costs. As a result, many installations are in
fact not being operated now.
Zaidi and Curran [38] recently carried out three test runs on a
new type of forced-air open pit incinerator constructed at the Gordon
Indian Reserve in northern Saskatchewan. The rate of generation of
domestic solid waste at Gordon, excluding the waste generated at the
residential school, was in the range of 907-1360 kg/week, or 4.2-7 m
week. The average composition (weight %) of the waste samples burned was
46% paper, 37% food, 3% plastic, 8% metal and 6% glass. It should be
noted that approximately 50% of the paper waste was disposable diapers.
The incinerator is a skid mounted, single chamber open pit type
incinerator capable of burning approximately 227 kg/h of municipal
type solid wastes. The combustion chamber is a refractory-lined metal
box with an inside volume of 2.7 m . It is designed to achieve a
temperature of 871°C by supplying up to 840 m /h of underfired
and overfired air through manifolds and nozzles mounted on both sides of
the combustion chamber.
From these three test runs it was found that the uncombustible
residue obtained from the incinerator indicated a fairly complete
combustion. The residue volume was approximately 15% of the refuse.
Also, to get a good fire burning in the incinerator, the volume of the
refuse at the beginning should be kept to a minimum. Therefore, it was
recommended that the collection of refuse be done in three batches with
the first one being the smallest [38]. Further testing of this facility
is planned.
Incineration is one of the most common methods of disposing of
solid wastes from industrial and military camps [36]. It is most
effective in reducing animal scavenging of the camp site and the
environmental effects of incineration are low. For very small, short
duration camps for exploratory purposes backhaul or open burning is
practised. For larger temporary and all permanent or semi-permanent
camps incinerators of various designs are used; they are normally oil
fired. Because of much better qualified operators than in communities,
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maintenance problems and costs are substantially reduced. Operating
costs are generally not available. They are probably high when
considered within an economic framework of a community, but are not
significant when considered against the overall cost of industrial or
military camp operations.
13.2.3.5 Milling and compaction. The purpose of milling and compaction
is to reduce volume, and thereby make handling and disposal of the wastes
cheaper and more manageable. Included here are methods to shred, mill or
grind wastes, and to compact or bale wastes. They may be used ahead of
landfilling, incineration or in conjunction with materials recovery. To
date the record of a number of pilot or full-scale projects appears to
increase overall disposal costs, rather than decrease them.
Refuse milling (or shredding, or grinding) is a process by which
refuse is passed through a mechanical device, such as a hammer mill,
which grinds it to a homogeneous mixture of a specified maximum size. This
mixture is inoffensive, light, highly compactable, and easily handled.
Paper plastic, wood, and cardboard are generally broken into three to four
inch pieces. Glass is shattered so thoroughly into sandlike particles that
it is impossible for the casual observer to detect it. The raw garbage is
generally absorbed and is so finely mixed with paper and other materials
that there is very little odour. The biggest problem is with soft plastic
bags, which tend to stretch rather than tear apart [5].
Milling ahead of landfilling reduces the need for daily cover
and the "nuisance aspects" of open dumps (odour, flies, rats, windblown
material). It also reduces the volume to be transported and disposed of.
Difficulties in northern operation of a hammermill, or other type of
mechanical equipment, are with the input of frozen wastes and increased
frequency of mechanical breakdown and difficulty of repair. Many
communities are too small to justify the high capital cost and operating
costs. Forgie [16] reported on a Canadian pilot project on shredding of
solid waste. It showed that shredding by a hammermill may be technically
feasible but failed to provide information on the economic feasibility
for northern applications.
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Compacting or baling is a process whereby waste, raw or milled,
is compressed into bales, with a significant increase in density (up to .
kg/L, which is about the density of water). After being banded, these
bales are hauled to a landfill site, where they can be stacked in place.
In this manner, greater landfill density can be achieved, and
transportation costs are reduced, since greater payloads can be hauled.
High pressure baling, which does not require banding, is planned for
Fairbanks, Alaska.
There is a lack of published economic analyses of these methods
which prevents a firm conclusion about their possible application in
northern areas. At present it appears that their benefits can be
achieved by simpler methods and managements as discussed previously
[24].
13.2.3.6 Recycling and reuse (haulback). Recycling of waste into
regenerated products is now popular. There are difficulties achieving
this objective in the economic framework of southern communities, and in
remote northern communities the picture is even less attractive.
Recycling and reuse requires, in many cases, sorting and separation of
wastes, as for instance in the recovery of metal cans, glass products,
etc. The size of the operation and the availability of markets for the
'usable' waste products are important economic considerations. A
northern location compounds the difficulties experienced in the southern
communities. Populations are generally small; therefore, volumes of
recovered materials are small. There are usually no local markets and,
therefore, material must be shipped south over long distances and at high
costs.
Some apparently successful projects of recycling scrap metal
have been reported by Kelton [5], In one project, approximately 40 000
tons of heavy metal scrap was removed from a Fairbanks junkyard and
transported by the Alaska Railroad to Seward, where it was shipped to
Taiwan for recycling, all without a government subsidy. Another example
is in Anchorage, where a private wrecking firm collects, crushes and
transports junked automobiles to Seattle, at a government subsidy of $22
per vehicle (1975). The problem of junked automobiles is discussed
further in Section 13.3.
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13.2.3.7 Costs and charges. Actual charges to the homeowner are not well
documented. However, information is available on the actual cost for
garbage collection and disposal in some northern communities. It is
important to differentiate between actual costs and charges. The latter
are mostly subsidized, and set without knowing real costs.
Gamble and Janssen [28, 32] describe a method to estimate the cost
of garbage collection in small communities. For the example illustrated,
Tuktoyaktuk, N.W.T., the cost per bag ranged between $1.49 and $2.89.
There is a need to document costs of collection and disposal in a number
of typical communities.
In Alaska, the average charge to the homeowner for collection of
garbage (one drum per week) in incorporated municipalities of over 500
population was $4.80 (2.50 to $15.00) per month per household in 1974 [5],
or about $1.20 per drum. In communities of the N.W.T., charges varied
between 40fc and $1.00 per drum in 1972 [20].
In Table 13-5, some typical values are given for the actual
costs (labour, vehicle O&M, overhead, etc.) to maintain garbage collec-
tion and disposal in some representative northern communities [39]. The
costs are given as either a flat rate charged per pick-up and/or as the
cost per person per year to maintain such a system.
TABLE 13-5. GARBAGE COLLECTION COSTS
Community
Coppermine
Fort Liard
Fort Resolution
Gjoa Haven
Fort Good Hope
Fort McPherson
Fort Norman
Paulatuk*
Aklavik
Chesterfield
Inlet*
Year of
Survey
1976
1977
1976
1976
1976
1976
1976
1977
1976
1976
Population
Serviced
758
225
600
420
443
710
232
147
781
243
Cost
$1.30/pick-up
$1.25/pick-up
$1.10/pick-up
$1.86/barrel
$1.28/pick-up
$1.15/pick-up
$15/person/yr
$16 . 25/person/yr
$14 . 25/person/yr
$38. 47/person/yr
$12. 17 /per son/ yr
$44 . 90/per son/yr
* Labour contract only.
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From Table 13-5 it can be seen that the smaller communities have
the higher per capita cost. This is reasonable because each community
will require similar infrastructures to allow for the garbage collection
system.
13.3 Industrial and Special Solid Wastes
Included under this heading are solid wastes generated from
industrial activities, special wastes such as discarded automobiles,
mobile houses, ski-doos, vessels, oil barrels, machinery and other bulky
waste, as well as special wastes associated with temporary or permanent
camps.
It is believed that no comprehensive survey has been done of the
solid waste problems of industry in Alaska and the Canadian northern
territories and provinces. Kelton [5] has provided some information on
the special problem of seafood processing wastes in Alaska, which are
disposed of in the ocean or in a landfill. A great part of industrial
activity in the North is connected with the extraction of raw materials
(oil, gas, various minerals, etc.). It is beyond the scope of this
manual to discuss the special solid waste management problems of these
industries in detail. Reference should be made to the relevant
information on such industrial wastes in other areas.
Special wastes, other than garbage and refuse, from communities
and camps include discarded automobiles, mobile homes, construction
equipment and materials, ski-doos, bulky containers and shipping
material, and others. These wastes do not accumulate on a frequent basis
and are normally not collected and disposed of routinely. However,
provisions must be made to provide an incentive for reuse, where this is
feasible, and more importantly, for a dumping area, which is controlled
and operated by the municipality. In the absence of this, discarded
material seems to be left almost everywhere. This contributes greatly to
the too often justified impression of unorganized and poorly managed
communities.
Some quantity information is available. Alter [6] stated: In
cold regions it may be assumed that the following percent of the total
weight or volume of each item becomes solid waste annually:
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- Lumber, steel and other building material used
in construction of fixed facilities such as
buildings 3%
- Heavy equipment, tractors, machinery and vehicles 10%
- Miscellaneous freight such as canned goods,
furniture, appliances, etc. 2-10%
- Magazines, books, newspapers, etc. 90%
- Office and household furnishings 5-10%
- Clothing 30%
These estimates may, in fact, be on the low side. For example,
machinery and cars accumulate more likely at a higher rate. Kelton [5]
estimated that of the 170 000 vehicles registered in Alaska in 1973 about
20 000 are junked each year. At an average weight of 1.5 tons per
vehicle this amounts to 30 000 tons of scrap per year. Recycling in the
larger and less remote communities may be economically feasible, but not
likely to be the case in the more remote communities because of high
freight rates. There is a choice to be made either between subsidizing
backhaul or providing local junk yards. Forgetting about the problem is
not acceptable. In the absence of state-or territory-wide policies, the
minimum that a local community must do is to establish 'controlled' junk
yards, prohibit the indiscriminate abandoning of discarded material on
public and private property, and establish a collection method at a fee
and on demand.
The special problems of solid waste management for temporary and
semi-permanent camps (together with their water supply and wastewater
disposal problems) have been discussed thoroughly by Grainge et al [18],
13.4 Human Wastes from Households and Establishments
The replacement of the "honeybag/honeybucket" system for human
waste disposal with other methods would be the greatest single
improvement in the living conditions of northern communities and would
contribute to a reduction in waste-borne diseases [2],
Hanks [21] has conducted an exhaustive literature study on the
relationship of solid wastes and disease. While the literature failed to
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13-22
permit a quantitative estimate of any solid waste/disease relationship,
this was said in summary:
"The communicable diseases most incriminated are those whose
agents are found in fecal wastes - particularly human fecal
wastes. Where these wastes are not disposed of in a sanitary
manner, the morbidity and mortality rates from fecal-borne
diseases in the population are high. Despite the fact that
other factors are known to contribute to some reduction of these
rates, the inescapable conclusion is that the continued presence
in the environment of the wastes themselves is the basic
causative factor. Therefore transmission - whether by direct
contact vector transfer, or indirect contact - is due to
environmental contamination of these wastes."
No other place in North America exists where this statement
applies more than in northern communities. There is a lack of conclusive
data for solid waste/disease relationships in northern communities, but
the problem is there.
The bucket toilet system, better known as the 'honeybag1 or
1honeybueket' system, exists because of the high cost of conventional
piped sewer systems, and the unsuitability of the septic tank-tile bed
system in most northern areas. Piped water and sewer systems, above or
below ground, suitably modified to northern conditions, have been
installed in many of the larger communities. The essential goal appears
to be the replacement of the honeybag system by a piped system, by a
holding tank/truck system, or by new methods such as internal recycle
systems. However, because of the many priorities for funds, it is
reasonable to expect that the honeybag system will continue to be widely
used for a considerable number of years. Improvements in current
praotioes are possible and discussed here. Surveys of communities'
municipal servicing standards, including human waste, were made for the
N.W.T. [19], the Yukon Territory [30] and Alaska [34].
13.4.1 Storage at the house and collection
Figure 13-12 shows a typical bucket toilet. Health officials
recommend that honeybags be collected from all households daily. This
also assists the collection procedure since a half-full bag is less
likely to break. Daily collection, however, is the exception rather than
the rule.
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13-23
FIGURE 13-12. TYPICAL BUCKET TOILET
There are three methods of honeybag storage and collection [20]:
a) collection from oil drums in front of each household,
b) collection from the bathroom of each household,
c) collection from the service porch of each household.
a) The householder is supposed to remove the honeybag from the
bucket toilet and place the sealed bag in a drum, reserved for this
purpose, in front of his house. Often, the bag is left on the ground,
where it is broken by birds, dogs or children, or where it can freeze to
the ground in winter. The presence of honeybags lying around the
settlement is aesthetically unpleasant. If broken, they constitute a
danger to health. Removal of honeybag debris is unpleasant, inconvenient,
and difficult. Handling, first by the householder and then again by the
collector, increases the possibility of breakage. This method is not
recommended (Figure 13-13).
b) A system of in-house collection of honeybags from the bathroom
has been implemented in some communities. The honeybag collector enters
the house and removes the honeybag and pail to the truck. After dumping,
-------
13-24
FIGURE 13-13. MANUAL HANDLING OF HONEYBAGS
STORED IN DRUMS IN FRONT OF THE
HOUSE UNTIL COLLECTION
a new bag is placed in the pail and the pail is returned to the bathroom.
The system is advantageous in that handling of the honeybag only once by
the collector minimizes the chance of breakage. It is convenient to the
householder, requiring no conscious actions on his part. Honeybags are
not left around the roads of the settlement where they may be broken.
Residents in at least one community have objected strongly to collection
from the bathroom as a serious inconvenience, which dirties up the house
and invades their privacy, and about which they were not consulted before
the system was placed in operation.
c) A variant of b) is the service porch or "two-bucket" system.
Each household has two plastic or metal pails for its toilet (Figure
13-14). Each morning the householder ties the top of the bag and places
the plastic pail and full bag in the service porch for collection. The
second pail, with an empty unused plastic bag inside, is placed in the
toilet for use. The collector removes the used bag from the pail and
replaces it with a fresh bag. The pail is left on the service porch for
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13-25
FIGURE 13-14. METAL BUCKETS USED FOR
COLLECTION OF HUMAN WASTE
use the next day, and the "full" honey bag Is taken to the collection
vehicle for disposal. The two-bucket system is advantageous in that it
minimizes handling of the bag, is clean, and does not leave honeybags
lying around the settlement. The major objection to the in-house system
- the invasion of privacy - is not present. The two-bucket system requires
that all homes have an accessible service porch and two toilet pails.
Trucks, on which tanks or drums are mounted for storage, are
used to haul the wastes to the disposal site. The most practical tank is
a half-round shape with a large manhole having a hinged lid on the back
in the flat cover. The flat top allows for a lower emptying point.
Steps are provided on the side so that honey buckets can be carried up
and emptied into the tank. The tanks usually have a capacity of 2000 to
3000 litres. The truck should be kept as small and manoeuvrable as
possible to get close to the houses. The tank should be capable of being
dumped at the disposal site. At the rear a large valved outlet pipe (at
least 20 cm in diameter) is provided which can be opened to empty the
tank. A small heater is needed to keep the short pipe and valve
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13-26
from freezing. The truck exhaust can also be routed to keep this valve
warm and eliminate the need for a heater. A full opening, non-rising
stem gate valve has proven best for this application as it must be
capable of passing solids such as plastic bags. A steam cleaner should
be mounted on the side of the tank so the honeybuckets can be cleaned
before replacement in the house. Typical costs for the truck, tank and
cleaning unit would be about $40 000 (1977).
Another type of truck has a large holding tank which is equipped
with a dumping drum with spikes on the interior of the drum. The full
honeybag is placed in the drum by the driver and broken on the spikes by
an upward hand motion. The contents flow or are sucked into the holding
tank, and the ripped bag is placed in an oil drum for the purpose of
storage before disposal (Figure 13-15). In a simpler case, honeybags are
placed in oil drums on the back of a tractor-driven cart or pick-up
truck. The drums with their contents are dumped at the disposal area and
the drums reused.
J
FIGURE 13-15. REAR VIEW OF HONEYBAG
SUCTION VEHICLE
-------
13-27
In some communities, homeowners must carry the bagged wastes to
a disposal point. Normally, several disposal points are located in the
village, and wastes are hauled from there by truck to the disposal site.
Disposal points must be centrally located to all dwellings; otherwise
their chances of being used regularly are small. The distance that
individuals will haul wastes varies with many factors. Two of the more
important considerations are training and education of the users and the
ground conditions over which the wastes must be hauled. Experience
indicates that the number of individuals who utilize a disposal point
starts dropping off considerably after the distance exceeds 200 metres.
Also, the people tend to haul longer distances in the winter because in
most communities it is easier to get around and snowmobiles can be used.
An extensive education program is invaluable in promoting the use of a
disposal point when individuals are hauling their own waste.
13.4.2 Quantity and composition of human wastes
Heinke and Prasad [22,23] have provided data for honeybag wastes
(Table 13-6).
Data from a Canadian community [9] substantiate the estimated
volume of about 1.3 L/person/day.
13.4.3 Disposal
Disposal of the contents of honeybags can be accomplished in
several ways. They are: at a treatment plant or a lagoon treating
sewage from a piped system; at a sludge pit-lagoon; at a disposal site
next to the garbage dump; on the ice; and in the ocean.
The most satisfactory disposal method for honeybucket wastes
would be at a central facility, such as a treatment plant where the
wastes are a small part of the total waste load to the facility. The
treatment would be accomplished by one of the methods discussed in
Section 9. A fly-tight closable box should be provided on the outside
of the building which is convenient to use. It must be capable of being
thoroughly washed down and cleaned daily. Above all, it must be
aesthetically pleasing and easy to use; otherwise it will not be used.
It must also be vandal-proof. This disposal method depends, of course,
on the existence of a partial sewer system and treatment facility, where
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TABLE 13-6. CHARACTERISTICS OF HUMAN WASTE (Honeybags)
Parameter
Volume, litres per person per day
PH
Alkalinity, mg/L
Total solids, mg/L
Volatile solids, percent of total solids
Dissolved solids, mg/L
COD, mg/L
Supernatant COD, mg/L
TKN, mg/L
NH3-N, mg/L
Org. N, mg/L
Phosphorus (PO^, mg/L
Volatile acids, mg/L
Total Coliform Count, no. per 100 ml
Average
1.3
8.78
14 990
78 140
77.53
39 290
110 360
48 510
8070
3920
4150
3730
2490
5.4xl08
Range
-
8.6 - 8.9
11 900 - 17 000
65 990 - 85 030
71.53 - 80.18
32 500 - 53 620
80 750 - 134 820
39 990 - 61 280
7280 - 9520
3470 - 4060
3696 - 5520
3400 - 4250
2300 - 2670
1.5xl08-2.3xl09
honeybags are used only in a portion of the community. If the wastes are
deposited in a lagoon a dumping point should be designed to prevent
erosion of the lagoon dykes yet allow for easy access so the waste
doesn't end up all over the dykes instead of in the lagoon. A platform
with a hole cut out over the water seems to be satisfactory. Another
problem with lagoon disposal is the plastic bags which are often used as
liners in honeybuckets. They are not biodegradable and should not be
deposited in the lagoon. It will be necessary to empty their contents
into the lagoon and then deposit the bags at a landfill or burn them. If
honeybag wastes are dumped at a treatment facility this must be taken
into account in their design. Although the hydraulic load is small the
organic and solids loading is quite considerable (see Table 13-6). The
waste may also contain a high concentration of deodorizers such as
formaldehyde and pinesol, which could affect biological treatment
processes.
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If a sewage treatment plant or lagoon does not exist, the most
satisfactory method is to build a sludge pit, lagoon or trench. It must
be accessible for easy dumping of the contents of haulage tanks. One way
would be to cover it with a platform which contains a disposal hole, and
covered with a fly-tight, hinged lid. The waste pit should be located on
a site which will never be needed for other purposes, and as far away as
practical from the community and water supply source. It should be sized
o
for about 0.55 m per person per year, and covered after one year's
operation and a new pit dug. If the community has a partial sewer system
and a lagoon is used as the treatment method, the sludge pit should be
constructed adjacent to the lagoon and liquid overflow directed to the
lagoon. Some of the liquid portion of the honeybucket wastes will seep
out when the surrounding ground is thawed. As with privies, sludge pits
are not a desirable form of waste disposal if the soil is frozen
fine-grained silts or where there is a high groundwater table. If no
other site is available, lining of the pit to prevent contamination of
the groundwater may be required.
A laboratory study carried out at the University of Toronto
[22,23] on a simulated waste pit showed that it is possible to treat
honeybag waste by anaerobic digestion at 20°C and that the process
may be applicable at lower temperatures, but at the expense of very long
detention times.
However, it does not appear economically reasonable to build an
anaerobic digester, with its requirement for heating, mixing and further
treatment of supernatant effluent, for the overall primitive honeybag
system. Disposal in a properly located, designed and operated waste pit
or trench is preferable to disposal in a garbage dump or in the ocean.
The two-year laboratory study, simulating a waste pit in permafrost,
showed that it acts as a holding tank only. No waste treatment occurs.
Pathogens are likely to remain viable in the pit for many years.
An improved method of handling and disposal of honeybags is
practised in Greenland [8]. Two communities (Holsteinsborg and
Egedesminde) have changed from the 'bucket-toilet1 system to a 'bag'
system. Homeowners are provided with strong paper bags lined with
plastic, and closing clips, which are placed inside the bucket. The bags
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are picked up and transported by a flat truck to a disposal station (see
Figure 13-16). One man at the disposal station empties the bags into a
discharge pipe (see Figure 13-17) leading to the ocean, below low water
level. The paper bags are burned. This system is considered a big
improvement in Egedesminde. In Holsteinsborg plastic bags are used,
rather than paper bags with plastic liners, and problems are experienced
in burning the plastic bags. The cost of the disposal station could not
be established but may be considerable, perhaps $150 000 (1973). It
makes the solids handling much more acceptable to the operators. The
expense of such a disposal station is justified only where the honeybag
system will continue to be used for many years.
The dumping of honey bags at a landfill site, on the ice or in
the ocean should not be encouraged, although there may be circumstances
which make this practice tolerable. If honeybags are deposited at a
landfill site, this should be separate from the garbage. Daily covering
with at least minimal material will prevent animals and birds from
getting into it. This is important to prevent disease transmission.
13.4.4 Costs and Charges
Presented in Table 13-7 are the actual costs involved for a
honeybag collection system in some northern communities [39]. These
costs are either given as a set charge per pick-up and/or as the actual
annual cost per person. This includes labour, material, vehicle O&M, and
overhead and profit costs for service provided by a contractor.
TABLE 13-7. HONEYBAG COLLECTION COSTS
Community
Coppermine
Gjoa Haven
Fort Good Hope
Fort McPherson
Paulatuk*
Chesterfield
Inlet*
Year of
Survey
1976
1976
1977
1976
1977
1976
Population
Serviced
758
420
443
710
145
243
Costs
$1.20/pick-up
$2.l5/pick-up
$1.85/pick-up
$1.50/pick-up
$l.!5/pick-up
$32/person/yr
$50/person/yr
$32.10/person/yr
$56.80/person/yr
* Labour and materials only.
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13-31
FIGURE 13-16. DISPOSAL STATION FOR HUMAN WASTE
AT EGEDESMINDE, GREENLAND
FIGURE 13-17. VIEW OF INSIDE OF DISPOSAL STATION,
EGEDESMINDE, GREENLAND
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13-32
Since all population sizes require similar infrastructures for
the honeybag system, it can be seen that the smaller population sizes
will have a higher per person cost. This, in fact, is supported by the
above data.
13.5 References
1. Associated Engineering Services Ltd. "Solid Waste Management in the
Canadian North", Environment Canada, Ottawa, March 1973.
2. Heinke, G.W., "Solid Waste Management in the Canadian North",
Environment Canada, Ottawa, March 1973.
3. D.R. Stanley Associates Ltd. "Solid Waste Management in the Canadian
North", Environment Canada, Ottawa, March 1973.
4. Underwood and MoLellan, "Solid Waste Management in the Canadian
North", Environment Canada, Ottawa, March 1973.
5. Kelton, K., "Comprehensive Plan for Solid Waste Management", Alaska
Department of Environmental Conservation, Juneau, Alaska,
January 1975.
6. Alter, A.J., "Solid Waste Management in Cold Regions", Scientific
Research Data and Reports, Vol. 2, No. 2, Dept. of Health and
Welfare, State of Alaska, College, Alaska, August 1969.
7. Grainge, J.W., "Study of Environmental Engineering in Greenland and
Iceland", Manuscript Report No. NR-69-5, Div. of Public Health
Eng., Canada Dept. of Nat. Health and Welfare, Ottawa, 1969.
8. Heinke, G.W., "Report on Environmental Engineering in Greenland and
Northern Scandinavia", Publ. Dept. of Civil Eng. 73-05, Univ. of
Toronto, October 1973.
9. Associated Engineering Services Ltd, "Report on Tuktoyaktuk Water
Supply and Waste Disposal" to Govt. of N.W.T., Yellowknife, July
1974.
10. Smith, D.W. and Straughn, R.O. , "Refuse Incineration at Murphy Dome
Air Force Station", Arctic Health Research Centre, Fairbanks,
Alaska, 1971.
11. Grundtwaldt, J.J., Tilsworth, T. and Clark, S.E., "Solid Waste
Disposal in Alaska". In : Smith, D.W. and Tilsworth, T.,
Environmental Standards for Northern Regions, A Symposium,
Institute of Water Resources, U. of Alaska, Fairbanks, 1975.
12. Can-Brit. Engineering Consultants Ltd., "Study of Solid Waste
Management at Indian Settlements in Northern Ontario", for
Environment Canada, Ottawa, March 1975.
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13. Straughn, R.O., "The Sanitary Landfill in the Subarctic", J. Arctic
Inst., Vol. 25, No. 1, March 1972.
14. Cohen, J.B., "Solid Waste Disposal in Permafrost Areas", Proc.
Second Int. Conf. on Permafrost, Yakutsk, pp. 590-598, Nat. Acad.
Sci., Washington, D.C., July 1973.
15. U.S. Army Corps of Engineers, "Technical Evaluation Study, Solid
Waste Disposal, Fort Greely, Alaska, Office of the District
Engineer, U.S. Army Corps of Engineers, Anchorage, Alaska, July
1972.
16. Forgie, D.J.L., "Shredded Solid Waste Disposal", IN Some Problems of
Solid and Liquid Waste Disposal in the Northern Environment,
Environment Canada Report EPS-4-NW-76-2, pp. 43-85, Edmonton,
November 1976.
17. Black, R.J., Munich, A.J., Klee, A.J., Hickman, L.H. and Vaughn,
R.D., "The National Solid Wastes Survey - An Interim Report",
U.S. Dept. of Health, Ed. and Welfare, October 1968.
18. Grainge, J.W., Edwards, R. , Heuchert, K.R. and Shaw, J.W.,
"Management of Waste from Arctic and Subarctic Work Camps",
Environmental-Social Committee, Northern Pipelines, Task Force on
Northern Oil Development, Government of Canada, Ottawa, 1973.
19. Heinke, G.W., "Report on Municipal Services in Communities of the
Northwest Territories", Information Canada, Ottawa, Cat. No.
R72-12674, INA Publ. No. QS-1323-000-EE-A1, 1974.
20. Cadario, P.M. and Heinke, G.W., "Manual for Trucking Operations for
Municipal Services in Communities of the Northwest Territories",
University of Toronto, Publication of Department of Civil
Engineering, October 1972,
21. Hanks, T.G., "Solid Waste/Disease Relationships, A Literature
Survey", Publ. of Public Health Service, U.S. Dept. of Health,
Education and Welfare, Report SW-K, Washington, D.C., 1967.
22. Heinke, G.W., "Preliminary Report on Disposal of Concentrated Wastes
in Northern Areas", in Report 74-10, Environmental-Social
Committee, Pipelines, Task Force on Northern Oil Develop., Inf.
Canada, Cat. No. R72-13474, QS-1577-000-EE-A1, Ottawa, 1974.
23. Heinke, G.W. and Prasad, D., "Disposal of Concentrated Wastes in
Northern Areas", IN Some Problems of Solid and Liquid Waste
Disposal in the Northern Environment, Environment Canada Report
EPS-4-NW-76-2, pp. 87-140, November 1976. Also in Proc. 3rd Can.
Hydrotech. Conf., Can. Soc. Civ. Eng., Laval University, Quebec,
pp. 578-593, 1977.
-------
13-34
23. Stanley Associates Eng. Ltd., "Baling for Solid Waste Management at
Baker Lake, N.W.T.", prepared for Northwest Region, Environmental
Protection Service, Environment Canada, Edmonton, 50 pp., 1974.
24. Underwood McLellan and Assoc. Ltd., "Report on Study of Pollution
Control Systems, Resolute, N.W.T.", Report to: Government of the
Northwest Territories and Environment Canada, Environmental
Protection Service, Edmonton, 1974.
26. Watmore, T.G., "Problems of Waste Disposal in the Arctic
Environment", Industrial Wastes, Zl(4), 24, 1975.
27. Zenone, C., Donaldson, D.E., and Grunwaldt, J.J., "Groundwater
Quality Beneath Solid Waste Disposal Sites at Anehorage, Alaska",
Groundwater, 1.3_(2), 180-190, 1975.
28. Gamble, D.J. and Janssen, D.T.L., "Estimating the Cost of Garbage
Collection for Settlements in Northern Regions", The Northern
Engineer, _6(4):32-36, 1974.
29. Heuchert, K.R., "Refuse Sack Collection System Study", IN Arctic
Waste Disposal - Social Program, Northern Pipelines, Task Force
on Northern Oil Development, Report No. 74-10, pp. 1-22, 1974.
30. Stanley Associates Eng. Ltd., "Final Report on Community Services
Improvement Program, Yukon Territory", prepared for: Dept. of
Local Government, Government of the Yukon Territory, Whitehorse,
292 pp., 1974.
31. Lindstrom, C.R., "Clivus-Multrum System: Composting of Toilet
Waste, Food Waste and Sludge within the Household", IN: Rural
Environmental Engineering Conference on Water Pollution Control
in Low Density Areas, September 26-28, 1973. Warren, Vt.,
Published by University Press of New England, Hanover, N.H., pp.
429-444, 1975.
32. Gamble, D.J.- and Janssen, C.T. , "Evaluating Alternative Levels of
Water and Sanitation Services for Communities in the Northwest
Territories", Can. J. of Civil Eng.. 1(1): 116-128, 1974.
33. Ryan, W.L., "Village Sanitary Problems", In: Environmental
Standards for Northern Regions, June 13-14, 1974. D.W. Smith and
T. Tilsworth, eds., Inst. of Water Resources, Univ. of Alaska,
pp. 315-320, 1975.
34. Village Sanitation in Alaska - Inventory. Office of Environmental
Health, U.S. Public Health Service, Anchorage, Alaska.
35. Alaska Department of Environmental Conservation, "Waste Oil/Water
Quality Problem Description" (Draft Report), Juneau, Alaska,
November 1977.
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13-35
36. Associated Engineering Services Ltd., "Waste Management for Northern
Work Camps", Environment Canada, Northern Technology Centre,
Edmonton, April 1978.
37. W.O. Wardrop and Associates Ltd., "Burning Practices in the
Northwest Territories", (Draft Report), Regina, March 1978.
38. Zaidi, A. and Curran, B., "Open Pit Incinerator", Report of
Saskatchewan District, Environmental Protection Service,
Northwest Region, Environment Canada, Regina, April 1978.
39. Doulton, B., "Water and Sanitation Operation and Maintenance Costs -
A Consolidation of Historic Information", prepared for the
Dept. of Looal Govt., Government of the Northwest Territories,
Yellowknife, 1978.
-------
SECTION 14
ENERGY MANAGEMENT
Index
Page
14 ENERGY MANAGEMENT 14-1
14.1 Basic Considerations 14-1
14.1.1 Energy requirements 14-1
14.1.2 Climate design information 14-3
14.1.3 System utilization and feasibility 14-4
14.2 Energy Supply 14-5
14.2.1 Fuels and storage 14-6
14.2.2 Heat and power production 14-12
14.3 Energy Distribution 14-21
14.3.1 Electric power distribution 14-22
14.3.2 Heat distribution 14-29
14.3.3 Gas distribution 14-38
14.4 References 14-43
-------
List of Figures
Figure Page
14-1 Kinematic Viscosity as a Function of Temperature for
Various Fluids 14-7
14-2 Output Characteristics of Various Common Electric
Generating Systems 14-14
14-3 Determination of Optimum Energy Cost and Plant Size
for Base and Peak Load Generating Plants 14-16
14-4 Winter Sea Temperatures off Alaska 14-18
14-5 Hot Water Accumulator for Thermal Storage Showing
Typical Interface Characteristics 14-19
14-6 Overhead Aerial 14-25
14-7 Underground Cable Guidelines 14-25
14-8 Directly Buried Hot Water Distribution Piping 14-32
14-9 Installation of Heat Distribution Lines in Seasonal
Frost Areas 14-33
14-10 Diagram for Determining the Required Insulation for
Frost Protection of Soils and Pipelines 14-35
14-11 Installation of Heat Distribution lines in Permafrost
Areas 14-36
List of Tables
Table Page
14-1 Residential Energy Requirements 14-1
14-2 Commercial and Institutional Energy Requirements 14-2
14-3 Rubber and Plastic Compounds Comparison 14-24
-------
14-1
14 ENERGY MANAGEMENT
14.1 Basic Considerations
A community requires energy for heating buildings, for lighting,
for operating appliances and for domestic hot water. Transportation energy
needs are not supplied by utilities. Industrial energy needs can be
supplied by utilities, but they are identified and added separately and are
not considered in this manual.
The energy requirements for heating depend on the climate and
vary with the season. Based on the pertinent climate design information,
the requirements can be estimated. Climatic information is also used for
the design of thermal protection for utility lines.
The strong seasonal variation in heating requirements and, to a
modest extent, the variation in electrical requirements, namely for
lighting, affect utilities and, therefore, their cost and feasibility. The
utilization can be estimated and used as a basis for selection of the
appropriate equipment.
14.1.1 Energy requirements
The heating requirements for buildings are controlled primarily
by the outside air temperature. Wind and sun have a lesser, more temporary
influence. The design and construction of a building determines its
thermal efficiency, of course, and affects its annual heating requirement
compared with another building. For planning purposes, typical values can
be used, based on the heating index. The heating index is expressed in
degree-days. The usual base in 18°C. Table 14-1 lists typical values for
residential heating requirements.
TABLE 14-1. RESIDENTIAL ENERGY REQUIREMENTS
Space Domestic Lights and
heat hot water appliances
kWh/°C d kWh/d kWh/d
Single residence houses 9 12 12-24
Multi-residence buildings 6 12 12-24
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14-2
Domestic hot water requirements are nearly constant throughout
the year. Table 14-1 shows typical daily requirements which may be
supplied through the heating system or through electricity. With
electricity, off-peak power can be used to heat water in individual
accumulators. With district heating, a low baseload is provided for the
summer season.
The typical lighting and appliances requirements of residences
are also shown in Table 14-1. The lower values are for summer conditions;
the higher values are for the winter. The difference is primarily due to
lighting requirements which are near zero in the summer.
Table 14-1 does not include electrical requirements for car
engine heaters, which are about 5 to 10 kWh/d per car during the cold
season.
The values for electricity use are typical daily totals. The
ratio of daily peak to average demand is 2 to 3 for a community. The ratio
for an individual residence is much higher.
The design heating system capacity is based on the winter design
temperature. The difference between the heating index base temperature and
the winter design temperature gives the number of degree-days and the
corresponding heating requirements per day. The daily peak load on a
district heating system is influenced mainly by the effeots of morning
warm-up after night set-back, and by heating needs during dropping ambient
temperatures, e.g., in the evening. The ratio of daily peak to average
load is about 1.2.
The commercial and institutional heat and electricity
requirements are summarized in Table 14-2. Electricity requirements are
more cyclical with the time of day than residential requirements.
TABLE 14-2. COMMERCIAL AND INSTITUTIONAL ENERGY REQUIREMENTS
Schools, offices
Schools, offices
Shops and retail
Food stores
< 1500 m2
> 1500 m2
stores
Space heat,
Wh/m2/°C d
65
65
60
60
Lights and
equipment, Wh/m /d
600
720
850
1400
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14-3
14.1.2 Climate design information
Climatic design information is given in Appendix H.
The heating index is a measure of the heating requirements of
buildings in a particular location. Table H-l gives the heating index for
various Alaskan communities, Table H-2 for various Canadian communities.
Degree-days are Fahrenheit. For conversion to degree-days Celsius, divide
by 1.8. Figure H-l shows the heating index distribution across Alaska,
Figure H-2 the distribution across Canada.
The design temperatures indicate the lowest temperatures that
can be expected in a particular location and provide a measure of the
needed capacity of the heating system. Table H-3 gives design
temperatures for various Alaskan communities, Tables H-4 and H-5 for
Canadian and Greenland communities. Temperatures are in degrees
Fahrenheit. Figure H-3 shows the distribution of design temperatures
across the contiguous United States.
The freezing index is a measure of below-freezing (below 0°C)
weather conditions and is used for computing frost penetration into the
ground. Frost penetration information is needed to define the depth of
water line burial or the amount of insulation necessary for protection.
Figure H-4 shows the freezing index distribution across Alaska, Figure
H-5 across Canada. Values are based on degrees Fahrenheit.
The thawing index is a measure of the summer climate. When
it is significantly smaller than the freezing index, the chances for
permafrost conditions increase. In permafrost areas, the thawing
index is used to compute the seasonal thaw penetration. Figure H-6
shows the thawing index distribution across Alaska, Figure H-7 across
Canada.
The mean annual air temperature is used in conjunction with the
freezing index for computing the ground frost penetration. Figure H-8
shows the mean annual temperature distribution across Alaska. Table H-6
gives temperatures for northern Canadian communities. The same table
also gives ground temperatures. Ground temperatures, including permafrost
temperatures, are typically a few degrees higher than the mean annual air
-------
14-4
temperatures. Alaskan ground temperatures are given in Table H-7 for
various communities.
Groundwater temperatures are a good ground temperature
indicator. In Alaska, the locations of many thermal wells are known,
even in permafrost areas, mainly because they are artesian. It is very
likely that there are many more thermal wells (non-artesian) or
undiscovered aquifers.
14.1.3 System utilization and feasibility
Electric and thermal utility systems are capital intensive.
For electric systems, the generating plants are the most expensive part;
for thermal systems, the distribution lines are most expensive. That
means, in turn, that thermal distribution systems have a smaller range of
coverage than electric systems, because they are limited to higher
density areas. Dispersed residential areas must use either delivered fuel
or they may be able to use off-peak electricity economically,
supplemented with solar heat.
To ensure economic feasibility, the system utilization must be
as high as possible. That means that the amplitude of the peaks and
valleys of the load curve should be minimized.
With electric systems, this goal can be achieved through
various demand management techniques which shift loads from peak to off-
peak periods. Heating of domestic hot water and electric storage heating
are examples of deferrable demands.
With thermal systems (district heating), the loads are governed
by the weather. Daily demand fluctuations are smaller than the seasonal
fluctuations. Seasonal storage has not yet been shown to be feasible.
The demand closely corresponds to the weather, and known climatic data
can be used to estimate the anticipated plant utilization.
The intensity of the winter weather, i.e., the winter design
temperature, determines the required plant capacity. The duration of the
cold weather, i.e., the heating index, determines the annual plant
output. The ratio of actual annual output to possible annual output
(at full capacity) is the measure of plant utilization. It is expressed
in hours per year of equivalent full capacity output. Full capacity is
-------
14-5
8760 h/a (hours per annum). For a district heating system, 2000 to 2500
h/a is a feasible utilization.
The anticipated plant utilization is computed from climate
information by:
heating index x 24 (h/a) (14-1)
18°C - design temperature
The actual utilization may be only about 90% of the value
computed from equation (14-1), or less, because the system usually has
excess capacity, e.g., to allow for growth and reserve.
As an example, the anticipated utilization is computed for
Anchorage Alaska, and Edmonton, Alberta. From Tables H-l and H-2 the
heating index values are 10789 and 10320 °F d, respectively. The values
of -25°F and -39°F from Tables H-3 and H-4 can be used for the design
temperatures. The resulting values for utilization are 2877 and 2381
h/a, respectively. Using 90% to obtain the anticipated actual
utilization, the following values result:
Anchorage 2590 h/a
Edmonton 2143 h/a
Figure H-10 shows a plant utilization distribution across the
contiguous United States which corresponds closely to utilization values
that result from the above calculation method.
A higher value for system utilization means that lower density
areas may be served economically, other things being equal.
As with electric systems, it is advantageous to have a mix of
baseload and peak load plants. Baseload plants are characterized by high
capital but low energy cost, for example, cogenerating plants (heat and
power). Peak load and reserve capacity plants have the opposite
characteristics and are used only intermittently. Gas turbines (without
heat recovery) are examples of peak load plants for electricity
production; boiler plants are examples for heat production.
14.2 Energy Supply
Energy supply in arctic climates is similar to that in other
climates. Some methods are employed to greater or lesser degrees due to
aretie conditions.
-------
14-6
14.2.1 Fuels and storage
The fuels and storage of fuels used in the arctic climate are,
generally speaking, the same as in temperature climates. However, there
are some special design elements which must be considered to ensure
reliable operation.
14.2.1.1 Selection of fuels. The petroleum products (gasoline, diesel,
etc.) used in arctic climates to power motor vehicles, trucks and air
craft are identical to fuels used in temperate climates, except for
possible octane levels, grades or additives which are controlled by the
different petroleum producers.
The one area in which fuel use varies is in the use of diesel
fuel. The one main property of fuel oil which is readily affected by the
cold climate is viscosity. Viscosity is the property of a substance
which makes it resist the tendency to flow. From Figure 14-1, it ean be
seen that fuel oil at moderate temperatures of 20°F to 60°F has a
kinematic viscosity of between 9 to 3.5 oentistokes. But when the
temperature drops to arctic conditions of -10°F to -60°F, the viscosity
of the fuel oil becomes extremely high, 25 to 500 centistokes. This high
viscosity presents a problem in that the fuel oil becomes so thick that
it refuses to flow. Fuel oil in above-ground tanks and piping which are
exposed to arctic temperatures often becomes too thick for burner pumps
to handle.
There are several solutions to this high viscosity problem.
One solution is to bury the fuel piping and storage tank to avoid
exposure to the cold temperatures. This is only practical for small tanks
of up to 190 nr. Another solution is the use of arctic grade diesel
fuel, DF-A, which has a much lower kinematic viscosity. From Figure 14-1,
it can be seen that DF-A fuel has a kinematic viscosity of 11.4
centistrokes at -30°F. This is a great improvement over other figures.
14.2.1.2 Storage and transport of petroleum fuel. The basics of fuel
storage are the same as those for water storage presented in Chapter 5.
The most common means of storing large quantities of petroleum products,
both in temperate and arctic climates, is large above-ground steel
storage tanks. The storage tanks used in both climates are generally the
-------
-60
-40 -20
0
25 50
Temperature °C
100
150
200 250
FIGURE 14-1. KINEMATIC VISCOSITY AS A FUNCTION OF TEMPERATURE FOR VARIOUS FLUIDS.
-------
14-8
same and are constructed to the standards set by the American Petroleum
Institute, Standard 650. The structural design of the tanks, in most
eases, is the same unless extreme snow and ice loads are expected, in
which case the structure is re-designed to carry the loads. One major
difference in storage tank design in the Arctic is the steel materials
used. Standard grade steel plates become less flexible and somewhat
brittle at extremely eold temperatures. For this reason, a different
grade of steel with good cold weather characteristics is used for tank
construction. The tank appurtenances also vary from temperate to aretie
climates. Water in the product is a very serious problem in any climate,
but in the Arcti© it presents some different problems. The water
draw-off connection on the tank is used to remove the water which
accumulates within the tank. Because of the arctic cold, the water
draw-off valve must be a non-freeze type valve. The design of a
non-freeze valve is such that the valve seat is mounted well back into
the inside of the storage tank, where the temperature of the product and
water is above freezing. If a conventional valve is used, the
probability of water in the valve freezing and cracking it is quite high.
This oould create a serious problem because when the frozen, cracked
valve thaws out, fuel will escape resulting in a spill.
Some storage tanks equipped with vapour-saving tank breathers
also present problems. The breathers will freeze up in cold weather
unless they are equipped with a flexible frost and ice resistant diaphragm
material. The breather screens also have a tendency to frost shut during
periods of extreme cold. Therefore, it is recommended that the screens
be removed during winter.
For the most part, petroleum products are transported by
pipeline, tank trucks, rail tank oars, and barges on sea and rivers,
whichever proves to be the most efficient and economical. In some cases,
petroleum products have to be air lifted into remote sites due to the
lack of road or rail service. In these oases, the petroleum products are
transported in drums or flexible bladder tanks.
Pipelines are probably the most efficient way of transporting
large quantities of petroleum products. Arctic construction of a
-------
14-9
pipeline is similar to methods used elsewhere in the world. There are,
however, a few problems encountered when routing a pipeline through the
arctic climate and terrain. Pipelines are generally not buried in
permafrost areas because the warm flow of product would melt the perma-
frost and the pipeline would gradually sink in the quagmire slurry
produced. If a pipeline is buried some form of thermal protection must
be provided for the permafrost.
Pipelines in permafrost areas are supported above-ground on
refrigerated pile supports. The refrigerated piles prevent the
permafrost from thawing, thus providing a solid foundation for the
pipeline.
Moisture or water in petroleum products presents a very serious
problem when the product is transported through pipelines or any other
system where it is exposed to freezing temperatures. The water freezes
and builds up by glaciering until a plug is formed. Damage to valves,
pumps, and other equipment could result. Therefore, it is essential that
water be removed from the product through water separators. These water
separators, along with other product transfer equipment, should be
enclosed in a heated shelter to protect the equipment and'provide a warm
working area in which to perform routine repairs and maintenance.
Transfer components, which are not enclosed in warm shelters
but are used in pipelines and other systems, require cold weather
considerations in their design. Control valves, flexible hoses, meters,
etc., should be designed from materials and components that will stay
flexible and operable at cold temperatures, such as polybuthylene
flexible plastic pipe.
14.2.1.3 Storage and transport of solid fuels. The most commonly used
solid fuel is coal. The storage and transport of coal is virtually the
same in both arctic and temperate climates. However, unloading and
storing of coal in arctic temperatures presents some problems. The coal
is usually washed at the mining operation prior to loading into the rail
oars. At cold temperatures, the wet coal quickly freezes into a large
rail-ear-shaped chunk of coal. The unloading area must be enclosed by a
shed type structure built onto the power plant over the traeks. The
-------
14-10
frozen coal oars are placed in the warm sheltered area for unloading.
The frozen coal is thawed and unloaded with steam probes and coal car
shakers. The coal, via conveyor belt, is then stored either in the plant
bins or in piles outside the plant. When coal is required from outside
storage piles, steam probes, bulldozers and loaders are used to thaw and
move the coal into the power plant storage bins. Once the coal is inside
the plant, one would think that no other problems would .exist. However,
because of the mass involved, the coal is still quite eold, contains
moisture and, once allowed to sit, will generally refreeze in the bins or
in the ooal chutes on the way to the boilers. This condition is usually
remedied with shakers attached to the chutes or bins.
14.2.1.4 Storage and transport of liquified gaseous fuels. The most
common fuel of this type used in the Arctic is propane gas. Propane is
transported the same way in both arctic and temperate climates, in
specially designed pressure tank cars and trucks. Propane is distributed
and stored in small pressure vessels which serve homes and small
businesses.
The one major problem with propane in the Arctic is related to
its vaporization characteristics. Propane, at temperatures below -45°C,
remains a liquid. This situation can become dangerous because a liquid
stream of propane is sometimes allowed to pass into piping leading to
utilities and appliances, causing fires and explosions. Propane tanks
exposed to these eold temperatures either require thick insulation or
enclosure in heated structure. If a heated enclosure is used, an
additional problem arises in that the enclosure must be ventilated to
prevent a build-up of explosive vapours. Another problem with propane at
sub-zero temperatures is that when the gas passes through the tank
regulator and valve, its expansion causes a drop in temperature,
resulting in frosting and freeze up of the regulator and valve.
14.2.1.5 Reliability, maintenance, security. The reliability of
petroleum product systems in the Arctic is basically the same as systems
constructed in warm climates, provided that the materials and components
used in the arctic construction are appropriate to the climatic
conditions. If arctic design procedures are followed, there should be no
-------
14-11
problem concerning reliability. Maintenance of petroleum product systems
in cold regions again does not present any serious problems.
Security of petroleum product systems in the Arctic is no
different from temperate climates. Tank farms, pump stations, etc., are
usually manned 24 hours a day and are enclosed with high security
fencing. Pipelines are inspected regularly by vehicle or helicopter.
14.2.1.6 Fuel spills and containment. The probability of a fuel spill
is virtually the same anywhere in the world. The largest cause of fuel
spills is related to human error or negligence of operating personnel.
Large spills generally start out as small leaks which can be stopped or
avoided by performing regular maintenance and inspections.
Containment of large or small petroleum spills is basically the
same in any climate. The most common methods of containing and
collecting spills consist of dike areas around tanks, collection weirs in
drainage ditches, drip pans, absorbents, etc. Dikes in cold regions are
generally constructed of gravel and rook with a layer of impervious local
soil as a liner. Membrane materials which remain flexible at low temp-
eratures, such as PVC and CPE, may also be used. Concrete dikes are not
always practical in the North because freeze-thaw action causes cracks in
the concrete walls to the point where spilled fuel would leak out.
Some problems are encountered in dike maintenance and operation
during the winter. Large snow falls are not uncommon and they are
usually followed by warm thawing temperatures and rain, which creates a
quick snow melt situation. This quick melt produces large quantities of
water which must be drained from the frozen dikes. A sump is usually
provided and a portable pump is used to pump out water which
accumulates.
14.2.1.7 Corrosion and grounding. Corrosion of petroleum storage and
transport systems in the Arctic presents virtually the same problems as
found elsewhere. Arctic soil and atmospheric conditions vary from
location to location, some being more corrosive than others. For
instance, those systems whieh are located along the arctic coast are
exposed to the corrosive action of salt air, whereas those systems inland
are only exposed to normal conditions. Soil conditions also vary
-------
14-12
considerably from one area to another. Areas containing peat bog are
usually acidic and very corrosive. Preventative measures taken against
corrosive conditions in cold regions are standard measures used elsewhere
in the world. Pipelines are cleaned, primed and wrapped before burial.
Storage tanks are protected inside and out with special coatings, etc.
Cathodic protection measures, magnesium anodes, are also used to help
prevent corrosion of buried product lines.
The battle against corrosion of steel used in product storage
and transfer systems is a universal problem and cold regions provide no
special problems.
Grounding of petroleum product systems is very important and is
required in all climatic conditions. Arctic designs are no different
concerning grounding of equipment and product lines to guard against
static discharge. In areas without permafrost conditions, the product
systems, including storage tanks, piping, buildings, water lines, metal
sewer lines, etc., are all bonded together and connected to grounding
rods whieh are driven into the ground. In some areas of the Arctic, the
ground conditions provide good grounding systems. Some areas may require
several ground rods or even a grounding plate set in a salt solution.
Permafrost areas present another situation. Areas with
underlying permafrost do not provide acceptable grounding conditions
due to the high resistance of frozen ground. In these areas, everything
is bonded together, including electrical wiring, POL piping, metal
building structures, storage tanks, water and sewer lines, etc., to form
one large grid network which can then be connected to a water well casing
which penetrates the permafrost layer, which in turn provides an
acceptable ground. If no well casing exists, then the grid system is
connected to a ground rod which does not penetrate the permafrost. This
will provide a common floating ground with everything at the same
electrical potential. This is acceptable as long as everything is bonded
to that common ground. Another practice is to place a grounding grid of
cable into a lake.
14.2.2 Heat and power production
The boilers and machinery that generate heat and electricity
are the same in cold regions as in temperate climates. Special
-------
14-13
considerations apply to the structures that support and contain them,
their reliability, their operating characteristics, their
construotibility, and other factors.
14.2.2.1 Central vs. independent generation. Electricity is generated
in central plants and distributed in cold regions as in temperate
climates. The reliability advantages of central plants with multiple
generating units are desirable, but added consideration must be given to
achieving corresponding reliability in the distribution network, which is
exposed to the severe climate conditions. The same holds true for
heating plants within the feasible distribution limits, even more so than
in temperate climates: heating needs are greater, favouring the eoonomie
benefits of district heating; the greater reliability is a vital factor;
and fire safety is enhanced by the elimination of combustion equipment in
every building.
14.2.2.2 Cogeneration. Whenever heat is generated, particularly for low
temperature uses such as space heating, the simultaneous generation of
electricity should be considered because most electricity is generated
from heat. Conversely, whenever electricity is generated, the
utilization of the waste heat should be considered. The advantage of
cogenerated electricity is the high fuel efficiency it attains compared
with single-purpose generated electricity. The amount of cogeneration
that is feasible is determined from an analysis of the thermal and
electrical loads supplied by the central plants, the output
characteristics of the generating equipment, and the ability to store
output (e.g., heat) for load management. Typical generating efficiencies
of different types of plants are summarized in Figure 14-2.
14.2.2,3 Strategic considerations. These are influenced not only by the
severity of the climate and the possible difficulties with logistics due
to remoteness, but also because the isolation of most installations or
communities requires a greater degree of self-sufficiency than with
interconnected systems. Diversity should be built into the system so
that alternate fuels can be used. Redundancy of equipment as well as
standby capacity must also be considered.
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14-14
63
33
23
1-75:
120;
25
L_J
W77A
BCD
Exhaust
Auxiliary losses
Waste heat
District heat
Electricity
40 Value in percent
30
35
35
H
35
A. Fossil fuel steam turbine power plant.
B. Fossil fuel steam turbine heat and power plant.
C. Fossil fuel heating plant.
D. Nuclear steam turbine power plant.
E. Nuclear steam turbine heat and power plant.
F. Gas turbine generator.
G. Gas turbine with heat recovery.
H. Diesel engine generator.
J. Diesel engine with heat recovery.
FIGURE 14-2.
OUTPUT CHARACTERISTICS OF VARIOUS COMMON ELECTRIC
GENERATING SYSTEMS. The output called "District Heat'
represents recoverable thermal output in the
temperature range of 80 to 120°C.
-------
14-15
14.2.2.4 Electric generating plants. Hydroelectric plants are
independent of fuel logistics problems and have the possible added
advantage of providing pumped hydro storage in conjunction with
eogeneration. They use renewable resources. In cold regions,
hydroelectric plants may be limited by icing or seasonally reduced
output. Large thermal eleetrie plants are typically baseload plants;
they are also likely candidates for eogeneration. Smaller units, usually
for peak load and reserve, may be gas turbine or diesel engine
generators. They require special consideration in the design of air
intakes and filters to avoid congestion by snow. This is achieved by
installing a heat exchanger in the intake plenium to sublimate the snow
or melt any possible ice build-up. It is not sufficient to depend on
open doors or windows in a generator building for air intake. The
combustion air requirement for diesel engines is about 3 std. m-Vh
n
per kW, and for gas turbines about 55 std. mj/h per kW output. Use
of wind energy, such as a vertical axis wind turbine, is limited by icing
problems that would be encountered on the turbine blades.
14.2.2.5 Heating plants. Fuel burning heating plants, also called
boiler plants, are low cost plants but the heat output is relatively
expensive because the cost of the fuel is high (fuel oil or natural gas),
and because electricity is not co-produced to offset the fuel cost.
Therefore, boiler plants are typically peak load and reserve plants.
Figure 14-3 shows how the overall cost is minimized by combining a
baseload plant with high first cost but low operating cost with a peak
load plant with lower first cost but higher operating cost. The baseload
plant is efficient at high utilization rates (above 4000 h/a in the
example), the peak load plant at low utilization rates. Boiler plants
burning coal, peat, or solid waste have lower fuel costs but higher first
costs. They are more like baseload or intermediate load plants.
When an indigenous source of low-temperature heat is available
for utilization through heat pumps, it offers an alternative with the
important advantage of independence, particularly when the electricity
used for the heat pumps is also generated from renewable resources.
Examples of low-temperature sources are ocean water, with year-round
-------
$ __$__
kWa MWh
14-16
Specific energy cost at optimum utilization
8x 103h/a
30 + 0.009 h/a
60 + 0.0015 h/a
i i i i i
// Peak load
V///////M
Optimum plant size
The specific annual cost curves of
two different generating plants
intersect at an abscissa value
which determines the cost
effective utilization of the plants
and their respective sizes from
the normalized load curve.
8x 103h/a
FIGURE 14-3.
DETERMINATION OF OPTIMUM COST AND PLANT SIZE FOR BASE AND
PEAK LOAD GENERATING PLANTS. The specific annual cost curves
of two different generating plants intersect at the abscissa
value which determines the cost-effective utilization of the
plants and their respective sizes from the normalized load
curve.
-------
14-17
temperatures of at least about 5°C, and groundwater (hydrothermal
sources), with those same minimum temperatures. Higher souree
temperatures are advantageous because the coefficient of performance
depends also on the temperature of the heat output; lower output
temperatures permit a higher coefficient of performance. For example,
with a source water temperature of 10°C and a delivery water temperature
of 60°C, a coefficient of performance of about CP = 2.6 can be expected.
That means that for each unit of electric energy used to drive the heat
pump, 2.6 units of thermal energy are delivered, while 1.6 units of
thermal energy are extracted from the source. If only 50°C is required
or, if instead the source temperature is 20°C, then the coefficient of
performance approaches CP = 3.0. Suitable sea water temperatures are
found along the coast of eastern Alaska (east of Valdez) and the west
coast of Canada (see Figure 14-4). Suitable ground water temperatures
are found in southwestern Canada.
14.2.2.6 Alternate energy sources. Alternative indigenous sources of
heat and electrical power generation are being seriously considered for
many northern locations. Although the benefits in terms of economics and
self-sufficiency are attractive, the technical and climatic limitations
are often greater in northern locations. For example, the use of solar
energy is limited by the shortness or absence of daylight hours during
the winter. Also, the use of wind generators may be limited by icing
conditions.
14.2.2.7 Storage. Hot water accumulators for heat distribution,
providing load management capability and reserve capacity, are feasible
in relatively larger sizes in cold regions than in temperate climates
because heating loads are greater and because greater reserve capacity
requirements are desirable. Figure 14-5 illustrates a storage
accumulator. Large insulated accumulator tanks do not have to be inside
buildings but the connecting lines and valves must be sheltered and
protected to reduce the danger of freezing.
14.2.2.8 Waste heat. All electricity generated from heat has also
"waste" heat as a byproduct, as stated by the Second Law of
Thermodynamics. This waste heat is unavailable to the process and
-------
U-18
-------
14-19
Diffuser
Discharging
Charging
Charging
Discharging
-Insulation
- Water tank
Centre of interface
(charge level)
Charging
Discharging
FIGURE 14-5. HOT WATER ACCUMULATOR FOR THERMAL STORAGE SHOWING TYPICAL
INTERFACE CHARACTERISTICS
represents usually about twice as much energy as that converted to
electricity (Figure 14-2). In ease of a steam turbine, the condenser
heat is produced at a temperature which is too low for space heating. If
a higher back pressure is used or steam is extracted before the last
stages, then it is less a case of waste heat utilization than a
modification for cogeneration.
Gas turbines provide heat from compresser intereooling and from
exhaust gases (after recovery for air preheating) at temperatures which
are suitable for district heating. Diesel engines provide heat from
jacket cooling and exhaust gases which is also suitable for district
heating. In these cases, cogeneration is possible using rejected "waste"
heat without process modification.
-------
14-20
Heat is recovered from exhaust gases from producing hot water
or steam with an economiser. This is basically a water tube boiler
without combustion chamber. Frequently, a boiler has an economiser built
to its back end for feed water preheating. When the economiser is
combined with a gas turbine or diesel engine, the engine serves as
combustion chamber and the economiser is the boiler. Jacket heat
recovery from the diesel engine is with a water-to-water heat exchanger
connected to the engine cooling loop. Such heat recovery boilers and
heat exchangers are standard equipment.
To recover heat from exhaust gases from a boiler or a gas
turbine for preheating combustion air, gas-to-gas heat exchangers are
available in the form of plate or tubular air preheaters, or Ljungstrom
rotating cylinder air preheaters.
The low-temperature heat, at 20 to 30°C, from a typical steam
turbine condenser is useable for such applications as municipal water
supply heating, including storage, and sidewalk, street or runway heating
for snow and ice control. The advantage of using low-temperature
heat is its low cost (low economic value) and frequently its great
abundance.
Waste heat which cannot be used must be dissipated. The
equipment required to dissipate waste heat represents a cost which must
be considered when evaluating the cost of equipment for utilizing it.
Also, the environmental impact of the waste heat must be considered.
14.2.2.9 Environmental impact. The thermal modification of a river or a
lake due to condenser heat dissipation from a steam power plant may be
either detrimental or beneficial to aquatic life. In any case, it will
cause more open water during the winter, and increased fog formation.
The same results from artificial cooling ponds. Open water cooling is
restricted in cold climates, even when abundantly available, and cooling
towers must be used. Wet cooling towers will also frequently cause fog
problems; therefore, dry cooling towers or wet/dry cooling towers must be
used. Cooling towers are more expensive than taking available water from
a stream and usually more expensive than constructing a cooling pond.
-------
14-21
Wet cooling towers are smaller and less expensive than dry towers but dry
towers have no adverse environmental impact.
Fog and air pollution problems are greatest in low lands or
valleys, particularly river valleys. Therefore, a power plant is best
located away from a valley or at least downstream from a community to
avoid contributing to air pollution problems. When a power plant must be
located in a low area, its chimney must be especially high to lift the
exhaust gases above the inversion and fog levels that occur normally
during the winter. A concentric chimney and cooling tower (i.e., chimney
inside of cooling tower) can improve lofting of the pollutants and reduce
the visible smoke plume.
14.2.2.10 Foundations. Permafrost presents special requirements for
foundations, different from those in seasonal frost areas. Foundations
of buildings containing machinery must also take into account vibration
in the design. Since foundations can shift in permafrost or severe
seasonal frost areas, the following measures should be taken:
a) Each boiler should be on a rigid slab with provisions for
levelling.
b) Turbine and generator or engine and generator units should
be on a common rigid slab with provisions for levelling.
o) Ducts and pipes should be routed overhead in the structure
and suspended to provide freedom for independent movement.
d) Points of transit of ducts, pipes and conduits through
building walls should be flexible so that swing movement is
possible on both sides of the wall.
e) Floor drains should lead into appropriate containments for
separation of water from oils, etc.
Where earthquake resistant designs are necessary, such design
features are basically compatible with and similar to the above
requirements.
14.3 Energy Distribution
The distribution of various energy forms in the Arctic is
similar to methods in other climates. However, many problems which are
unique to the Arctic require use of special equipment and techniques.
-------
14-22
14.3.1 Electric power distribution
The distribution of electric power in arctic and subarctic
regions is generally similar to those practices which have also proven
safe and economical in temperate climates. The specific environmental
considerations related to extreme low temperatures, snow, ice, wind, and
permafrost are the important factors that the designer, contractors, and
maintainers of electrical distribution systems must be concerned with.
14.2.1.1 Distribution methods^ Both aerial and underground methods of
electrical distribution have been successfully used. Wood pole lines,
and both self-supporting and guyed metal towers have been used for high
voltage transmission and distribution lines. The design of foundations
for these structures in localities where seasonal frost and active layers
vary is of prime consideration. Foundation soils must be carefully
evaluated. Underground distribution methods must employ means to
stabilize, equalize, and protect buried cables from mechanical damage.
Non frost-susceptible materials must be used in all pads, foundations,
and trenches for electrical distribution systems. Utilidors and duct bank
systems, if used, must be reinforced to withstand structural displacement.
Prime consideration should be given to placing structural gravel and non
frost-susceptible material pads on top of the active freeze-thaw layer,
effectively burying cables above the existing or surrounding ground level.
Surface laid wood utilidors placed on gravel pads have also been used
successfully.
14.3.1.2 Aerial. Aerial electrical distribution systems should be
selected and designed for the basic economic factors that normally dictate
standard voltage, conductor, transformer, and substation sizes. Increased
safety factors which consider the extremes of the climate are the
important parameters to consider. Extreme wind chill factors make routine
repairs "slow". Simplicity of construction is essential.
Additional structural, conductor, and apparatus strengths are
required where severe wind, snow, ice loads, and low temperatures are
anticipated.
Indoor/outdoor modular apparatus designs are desirable where
severe weather conditions are anticipated. Cable terminal buildings, sub-
-------
14-23
stations, and power transformers should be designed to protect equipment
from the elements. Snow sheds, frost shields, and windbreaks are
desirable features wherever possible. Localized heated compartments
within larger structures in substations are helpful and provide the
necessary ambient temperatures for standard apparatus.
In aerial distribution construction, wood poles have been set
into the permanently frozen soils during the cold season when the top
active zone is also frozen. This permits easier construction on and
across tundra, swamp, and small pond/lake areas. Specifications for pole
depth settings have generally used the gravelly soils criterion of 10
percent pole length plus another additional four feet (e.g., 50-ft poles
set 9 ft). These wood pole structures were in the average range of 50
feet, classes 2 to 4.
Consideration can also be given to "tripod" pole configuration
without pole burial; gravel-filled oil drums or rock-filled cribbing will
provide stability. For camp distribution systems, masts supported on the
buildings can serve to distribute secondary power, a common practice in
Europe.
14.3.1.3 Underground. Underground electric power distribution systems
should be selected and designed with the same economic factors relevant
to the aerial system, i.e., voltage, ampacity, and loss considerations.
In addition, the flexibility of cable insulations and jackets are
important factors where extreme low temperatures are found.
Both primary (above 600V) and secondary cables must be
installed so that bends, tensions, splices, and terminations are properly
made. Underground distribution standards that cover such items as the
grounded neutral insulation ratings, basic impulse levels (BIL), and
corona extension levels, etc., are available to the designer.
Construction may warrant special conditions and additional safety
factors. Lines should be placed below the seasonally active depth. Table
14-3 provides a comparison of rubber and plastic compounds. Figures 14-6
and 14-7 illustrate items considered of prime importance for both under-
ground and overhead aerial systems.
-------
14-24
TABLE 14-3. RUBBER AND PLASTIC COMPOUNDS COMPARISON
Rubber Insulation
Oxidation Resistance
Heat Resistance
Oil Resistance
Low Temperature Flexibility
Weather, Sun Resistance
Ozone Resistance
Abrasion Resistance
Electrical Properties
Flame Resistance
Nuclear Radiation Resistance
Water Resistance
Acid Resistance
Alkali Resistance
Gasoline, Kerosene, Etc. (Aliphatic
Hydrocarbons) Resistance
Benzol, Toluol, Etc. (Aromatic
Hydrocarbons) Resistance
Degreaser Solvents (Halogenated
Hydrocarbons) Resistance
Alcohol Resistance
SBR
(Styrene
Butadiene)
F
F-G
P
F-G
F
P
G-E
E
P
F-G
G-E
F-G
F-G
P
P
P
F
Natural
F
F
P
G
F
P
E
E
P
F-G
G-E
F-G
F-G
P
P
P
G
Syn-
thetic
Natural
G
F
P
E
F
P
E
E
P
F-G
E
F-G
F-G
P
P
P
G
Poly-
buta-
diene
G
F
P
E
F
P
E
E
P
P
E
F-G
F-G
P
P
P
F-G
Neo-
prene
G
G
G
F-G
G
G
G-E
F
G
F-G
G
G
G
G
P-F
P
F
Hypalon
(Chloro-
sulfo-
nated
Poly-
ethylene
E
E
G
F
E
E
G
G
G
G
G-E
E
E
F
F
P-F
G
NBR
(Nitrile
or Buta-
diene
Acrylo-
nitrile)
F
G
G-E
F
F-G
P
G-E
P
P
F-G
G-E
G
F-G
E
G
P
E
EPR
Ethylene
Propy-
lene
Rubber
G
E
F
G-E
E
E
G
E
P
G
G-E
G-E
G-E
P
F
P
P
Butyl
E
G
P
G
E
E
F-G
E
P
P
G-E
E
E
P
F
P
E
Silicone
E
0
F-G
0
0
0
F
0
F-G
E
G-E
F-G
F-G
P-F
P
P-G
G
Plastic Insulation
Oxidation Resistance
Heat Resistance
Oil Resistance
Low Temperature Flexibility
Weather, Sun Resistance
Ozone Resistance
Abrasion Resistance
Electrical Properties
Flame Resistance
Nuclear Radiation Resistance
Water Resistance
Acid Resistance
Alkali Resistance
Gasoline, Kerosene, Etc. (Aliphatic
Hydrocarbons) Resistance
Benzol, Toluol, Etc. (Aromatic
Hydrocarbons) Resistance
Degreaser Solvents (Halogenated
Hydrocarbons) Resistance
Alcohol Resistance
PVC
(Poly-
vinyl
Chloride)
E
G-E
E
P-G
G-E
E
F-G
F-G
E
P-F
E
G-E
G-E
G-E
P-F
P-F
G-E
Low-
Density
Poly-
ethylene
E
G
G-E
G-E
E
E
F-G
E
P
G
E
G-E
G-E
P-F
P
P
E
Cellular
Poly-
ethylene
E
G-E
G-E
E
E
E
G
E
P
G
E
G-E
G-E
P-F
P
P
E
High-
Density
Poly-
ethylene
E
E
G-E
E
E
E
E
E
P
G
E
G-E
G-E
P-F
P
P
E
Poly-
propylene
E
E
E
P
E
E
F-G
E
P
F
E
E
E
P-F
P-F
P
E
Poly-
urethane
E
G
E
G
F-G
E
0
P-F
P
G
P
F
F
F
P
P
P
Nylon
E
E
E
G
E
E
E
F
P
F-G
P-F
P-F
E
G
G
G
P
Teflon
0
0
0
0
0
E
G-E
E
0
P-F
E
E
E
E
E
E
E
P = poor
E = excellent
= fair G = good These ratings are based on average performance of general purpose
0 = outstanding compounds. Any given property can usually be improved by the use
of selective compounding.
-------
14-25
INSULATOR
CONDUCTOR
Alternate method for
dead end assembly
STRUCTURE
•
Freeze/thaw zone
Permafrost
FOUNDATION
Foundation - Recommend polyethylene pole "blanket" and/or non-frost
susceptible materials in active zone. In permafrost, 10% +
1.2 m for pole setting depth
Favor wood pole when less than 60 ft. for helicopter setting.
Safety factors considered.
In low rain arctic areas use extra dead end suspension bells
to reduce contaminant flashover. Recommend tongue and clevis
for suspension assembly.
Conductor - Standard ACSR sizes: Secondary insulated/low temperature
flexibility.
FIGURE 14-6. OVERHEAD AERIAL
DIAGRAMETRIC-CABLE SYSTEM SECTION VIEW OF PAD OR ROADWAY
TERMINATIONS
II
SPLICES
INSULATION/JACKET
Cables buried in
toe of roadway
Gravel pad -\ [—Roadway —*j
% XJ.l fl- •....'.' • . U- •«' '' "T^^^TT^ M
I v^^^i** tf"*?.' •' t9"Q"V,** " • • *."« f ".,•»•' * 'J
Active layer
.
Freeze/thaw zone
Permafrost
Recommendations
Insulation/Jacket - Low temperature flexibility favor solid dielectrics, and
ethylene propolene types.
Splices - Manufacturers kits, instant slip-on terminators to eliminate pouring
hot compounds, and building taped stress cones in field.
Terminations- Taped stress cones in field.
FIGURE 14-7. UNDERGROUND CABLE GUIDELINES
-------
14-26
14.3.1.4 Special considerations. There are certain special
considerations and problems that pertain to construction of electric
distribution utilities in cold regions. These are not necessarily
impossible to solve but require care and thought in the selection of
materials, methods of installation, and followup maintenance.
A general list of items is as follows:
1) Nylon jacketed conductors (types THWN). When used at low
ambient temperatures, the insulation tends to separate from
the jacket.
2) Cold weather starting of gaseous discharge lighting.
Mercury vapour type is especially hard or impossible to
start. Ballast low-temperature ratings must be checked for
minimum starting temperatures; otherwise luminaries must
remain energized continuously during extreme lows or
provided with integral thermostats to start luminaries when
the temperature drops below -30°C, the present low limit of
ballast manufacturers' ratings.
3) Molded ease circuit breakers and stored potential switches
are not 100 percent dependable at extreme low ambient
temperatures. The alternative use of fuses and an adequate
supply of spares must be evaluated, or supplemental heat
provided to raise the ambient temperature of the equipment
enclosure.
4) Pole jacking occurs when frost heaves and soil freeze/thaw
conditions displace alignment of overhead pole lines.
Polyethylene pole blanket sleeves have been specified and
used for some utilities. A pole sleeve of 10 mil black
polyethylene can be slipped over the base of the pole and
sealed moisture tight. This permits seasonal frost heaving
without pole jacking. The plastic double-walled sleeve
prevents frost bonding to the wood pole surface.
5) The resistance of grounding electrodes and earth grounds in
frozen soils varies according to the temperature. Aretic
-------
14-27
research papers by the U.S. Army Cold Regions Research and
Engineering Laboratory (CRREL) have treated this subject [1].
6) Cold-temperature special alloy steel is being specified for
transformers, circuit breakers, and other exterior electrical
distribution apparatus and specifications for equipment
subject to extreme low temperatures is described in
reference [2],
7) Aerial conductor vibrations, aoelian and galloping. Arctic
environments, especially near coastal regions, present
unpredictable storm combinations that make normal service
access impossible. The extreme low temperatures mandate
critical evaluation of mission objectives. Power
interruptions of several hours may result in building
freeze-ups. Added safety factors must be applied.
Consideration should be given to the use of steel
conductors to provide melting of ice on conductors, or the
use of strain gages on conductors to sense critical ice
loading and sound an alarm or pre-schedule line "short-
circuiting" to melt ioe. All deadend primary insulators
should be tongue and clevis type. Reliance on cotter keys
alone is inadequate. All pole-mounted hardware should be
nut and cotter key to nut and "pal" lock-nut.
Aeolian vibration control is covered in Stockbridge
[3], and dumbell torsional dampers plus armor rods should
be used at all primary cable conductor supports.
Cataclismic failures are not associated with aeolian
vibrations. Frequent conductor inspection is required to
identify areas of severe conductor fatigue to prevent
conductor failure.
The "galloping" conductor phenomenon is endemic to all
areas. In general, conductor spacing must allow for
elliptical loop dancing in the single conductors to prevent
short circuit phase-to-phase faults. Mechanical
-------
14-28
considerations, however, present the greatest area of
challenge. It is not possible with the present
state-of-the-art to eliminate "galloping". In severe
galloping areas, conductors should be dead-ended at each
pole, or preferably the transmission line should be
rerouted or an underground cable routing selected. Dense
cold winds from glaciers and ice fields have been known to
reach velocities of over 300 km/h near the sea, coincident
with 152 mm of radial ice [4], Catastrophic mechanical
damage to towers, insulators, and hardware can be minimized
by the use of slack spans in relatively short runs of 90 m
or midspan spacers in longer runs of up to 300 m.
In general, cold regions do not always have a recorded history
of meteorological data upon which to base a pole/tower line design. For
this reason conservative design must be used.
14.3.1.5 Reliability, maintenance, and security. Reliability of
electric power distribution is the norm rather than the exception. If
the major items offered in the previous paragraphs on special
considerations are acknowledged and the weak links are eliminated, then
reliability is measured further by adoption or use of the following
individual job features: dual feeders, loop/radial circuits, parallel
transformers, dual busses, additional switohgear and generation units.
These all add up to planned reliability.
Maintenance is enhanced by enclosing complex apparatus in
modules or enclosures where the cost of such structures warrant their
use. Consideration should also be given to providing "line-men" weather
shelters with emergency survival gear in inaccessible areas. Helicopter
access is not predictable and ground crews in all-terrain vehicles may be
required to make emergency repairs in nonflying weather conditions.
During helicopter operations, rather than use standby time, options are
usually for return piek up. Sudden weather changes have isolated line
crews for as long as a week [4], Buried multiplate steel culvert
storerooms have been considered expedient in instances where fast,
-------
14-29
efficient helicopter supported erews must work many miles from larger
warehouses. If an area is a severe environmental hazard or has a low
safety factor then, for example, spare insulators, hardware, and
accessories may be kept looked and secure from the elements.
Security is usually handled with scheduled maintenance and
inspection trips. "Flying the line" or overland inspection trips are
considered most expedient where daylight in the Arctic- is reduced. When
darkness prevails, operation, maintenance and security lighting becomes
an important factor. Vehicles equipped with inspection lights and/or
banks of auxilliary lighting and standby generators for power are
considered important. Small helicopters equipped with high intensity
spot/flood lights are being used for security and maintenance
purposes.
14.3.1.6 Communications lines. Design, construction, operation and
maintenance of communications lines in cold regions are considered
standard practices of 'outside plant work'. Until recently long haul
communications in the Arctic have been via tropospheric radio and
microwave methods. Satellite communication is now being used for some
remote military and civil bush communications links. Communications at
remote sites, villages, military encampments, experimental and operation
stations are normally handled by telephone or radio telephone equipment.
In these locations standard local telephone exchange equipment practices
are used. Outside plant overhead and underground installations are
usually constructed during the summer months. Protection of overhead
lines and underground communications systems from failure presents the
same mechanical/electrical environmental problems as with electric
distribution.
14.3.2 Heat distribution
Heat distribution networks in cold regions require particular
attention to the seasonally restricted conditions for construction, and
the influence of frost on operation and maintenance. The greater heating
needs in cold regions enhance the feasibility of providing district
heating. Minimum density limits of 15 to 25 MWh/km^ are typical of
-------
14-30
Swedish district heating experience. This corresponds to about four
residences per acre. The lowest densities can be served economically
where they are an expansion of an existing system or where a residential
area is adjacent to a trunkline leading to another large area being
served. Another factor influences the feasible density limit: a coastal
climate location with a long heating season but without extremely cold
weather will provide a greater system utilization (more equivalent full
load hours) than a continental climate location with its greater
temperature extremes and will, therefore, make lower load densities
feasible. For example, in Sweden and Finland, the typical system
utilization is 2000 to 2500 h/a; in Iceland, it is nearly 4000 h/a.
14.3.2.1 Temperatures and fluids. It is principally advantageous to
use the lowest practical fluid temperatures for heat distribution because
losses and total costs are minimized. The temperatures required inside
the building for heating purposes are usually no more than 80°C during
the coldest weather, and less during milder weather. Heating systems
requiring supply temperatures not exceeding 50°C and even less are being
built. Temperatures over 100°C are only needed in special situations
such as in buildings with process heat requirements. These may be met
more economically with auxiliary heating equipment than by using high
temperature distribution throughout the whole system.
Water has important advantages over steam for heat
distribution. Low distribution temperatures are possible; both
temperature and flow rate can be varied to permit almost infinite
delivery modification; the ability to operate with low temperatures
minimizes heat losses and permits more pipe material alternatives;
thermal storage facilities can be readily incorporated into the system
because water itself is an efficient storage medium.
A glycol-water solution can be used instead of plain water for
freeze-prevention, e.g., in an intermittantly operating system. The
disadvantages of the glycol solution are greater viscosity and lower
specific heat than water, resulting in greater pipe size, fluid cost and
pumping power requirements.
-------
14-31
14.3.2.2 Buried distribution piping. This concerns directly buried,
insulated piping. A wide variety of insulating methods or pre-insulated
pipe systems are being used. Figure 14-8 shows examples of the principal
types of systems being used. Their selection and applicability depends
somewhat on the soil moisture conditions. Directly buried piping is less
expensive to install than piping in conduits but its service life
expectancy is also less.
The primary distinction is between installations in seasonal
frost areas and permafrost areas. Within these areas there are
considerations based on the frost-susceptibility of the soils. Peat,
clay and silt are frost-susceptible soils; they retain large amounts of
water. Sand, gravel and rock are non frost-susceptible; they drain the
water. Frost penetration is deepest in the least frost-susceptible soils
and under snow-free areas.
In seasonal frost areas it is always safe to place the piping
below the seasonal frost depth (Figure 14-9A). Shallow burial is less
expensive. In non frost-susceptible soils it can be accomplished without
special measures (Figure 14-9B). In frost-susceptible soils a frost
shield must be added (Figure 14-9C) to prevent heaving and rupture of the
lines. Installation on grade is less expensive than burial and is
efficient where it causes no interference. The soil cover provides
protection (Figure 14-9D). The frost shield protects from heaving in
frost-susceptible soils and from excessive cooling in non frost-
susceptible soils. Elevated construction may be necessary in some areas
where obstacles, high groundwater or other reasons make it necessary
(Figure 14-9E).
The purpose of the frost shield is to prevent the soil under
the pipes from freezing and heaving. The water in the pipes themselves
is hot and protected, as opposed to cold water pipes, which are not
insulated themselves, and depend on the shield for protection. The heat
dissipation from the insulated hot water pipes is greater than from bare
cold water pipes. Therefore, more extreme frost conditions can be
encountered than with cold water pipes. In fact, cold water pipes can be
protected by co-location with the heat distribution pipes. The most
-------
14-32
Conduit pipe
Insulation
HW Pipe
B
Steel carrier pipe
Fiber reinforced polyester pipe
High density polyethylene cover
High temperature polyurethane foam insulation
— Vapor permeable water barrier
Insulating concrete
Drain pipe
Structural concrete base
•' '>.'• o
Steel or copper carrier pipe
' Polyurethane or
glass fiber insulation
High density polyethylene jacket
A. Pipe-in-pipe system. Supply and return service lines in common
conduit pipe.
B. Individual pipe-in-pipe main distribution lines.
C. Pre-insulated distribution piping with integral extruded jacket.
D. Pre-fabricated insulating culverts for slip-on assembly.
E. Cast-in-place insulating concrete block.
FIGURE 14-8. DIRECTLY BURIED HOT WATER DISTRIBUTION PIPING
-------
•fs
U>
Co
-------
14-34
severe exposure is in the case of pipes on grade under a berm (Figure
14-9D) because it is desirable to keep the berm height to a minimum. The
dimensions of the U-shaped frost shield can be determined by the method
given by Gundersen [5] and illustrated in Figure 14-10. The
determination is based on soils of sand and gravel which experience
greater frost penetration than clay and silt. Figure 14-10 applies only
to non frost-susceptible soils.
In permafrost areas, direct burial is possible in non
frost-susceptible soils. A thaw zone develops around the pipes (Figure
14-11A). A drain pipe is necessary if burial is shallow so that the
seasonal thaw depth reaches the thaw zone around the pipes, permitting
surface water to drain into it. In frost-susceptible soils a thaw shield
is necessary to avoid instability problems (Figure 14-11B). Trenching in
permafrost requires appropriate equipment for cutting. This cost is
avoidable where on-grade installation is acceptable. A thaw shield is
necessary to avoid soil thaw instability and water accumulation (Figure
14-11C). The soil cover provides protection. Elevated construction is
possible where necessary in all soils, as in seasonal frost areas (Figure
14-11D).
14.3.2.3 Distribution piping in conduits. Conduits include all kinds of
utilidors, culverts and ducts, whether below or above-ground. They are
discussed in Section 8. The piping is installed in the conduit on
supports using either preinsulated pipe or insulating it separately after
installation. The installation is basically the same as inside a
building. There must be fixed-point supports and also sliding supports
to allow movement due to thermal strain of the pipes, as well as for
movement of the conduit due to frost (or seismic) action. In large,
walk-through utilidors the piping is accessible for installation and
maintenance at all times. Smaller buried ducts are only open during
installation with normal access subsequently limited to manholes.
Elevated ducts can be made with removable side panels for later access or
installation of additional lines. A buried duct with its top at ground
level can be made accessible through removable cover plates; the top
surface can serve as a walkway.
-------
14-35
Insulation thermal resistance (m2»K/W)
1.4 50mm 1 Extruded
2.1 75mm > polystyrene foam
2.8 100mm J
Freezing index (h°.C)
40000 60,000
j. L 1
4.0 3.0 2.0 1.0
Insulation width (m)
FIGURE 14-10. DIAGRAM FOR DETERMINING THE REQUIRED INSULATION FOR FROST
PROTECTION OF SOILS AND PIPELINES
Source: P. Gundersen, Norwegian Building Research Institute [5].
-------
14-36
.'D.
Seasonal thaw depth
Earth berm
Insulation
\ Seasonal thaw depth
OPC —'
VL.
Drain pipe to sump
Gravel
and /or sand
Insulation
Drain pipe to
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5onal thaw depth "? ; v ••'';•?••
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\ Pipe sleeve
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depth
rotecti
B
A. Deep or shallow burial in non frost-susceptible soils.
B. Shallow or deep burial in frost-susceptible soils.
C. On-grade installation with earth cover on frost-susceptible and
non frost-susceptible soils.
D. Elevated installation over all soils.
FIGURE 14-11. INSTALLATION OF HEAT DISTRIBUTION LINES IN PERMAFROST AREAS
-------
14-37
For the design and construction of the conduits, the
considerations for frost are the same as for directly buried piping.
Heaving as a result of freezing and instability due to thaw must be
avoided. Inside the conduit, water from leaks or infiltration must be
able to drain freely to sumps with pumps at low points of the route. The
conduits also should have vent pipes extending above-ground at intervals
of not more than 50 m for venting and drying with suction blowers or
compressed air. In areas with severe or bad water conditions in the
ground, drain tiles should be placed under the conduit leading to a dry
well or sump with pump at low points of the route.
The conduit does not need to be heated but its cover should be
insulated to prevent condensation followed by dripping on the pipe
insulation. When sewer lines or uninsulated oold water lines are placed
in the same conduit, its walls should be insulated and heating can be
provided by reducing or eliminating the insulation on the return pipe of
the heat transmission line so that the temperature in the conduit remains
above freezing. For conduits above-ground the heating requirements can
be calculated from the heat transmission factors ("U" values) of the
conduit walls and the anticipated ambient air temperatures. For buried
conduits, the heating requirements can be determined from information
given by Gundersen [5],
14.3.2.4 Reliability, maintenance, security. The distribution network
is the most expensive and vulnerable part of the utility system. The
consequences of failure are more severe in cold elimates than under
temperate conditions. The reliability of a distribution network can be
increased by interconnecting adjacent service areas, and by forming a
ring of trunk lines so that a pipe failure or shutdown can be isolated
and loss of service can be avoided as much as possible. The maintenance
of lines is easiest in large walk-through utilidors but these are only
feasible for trunk lines, particularly where several utilities use the
same utilidor. Buried duets are less maintainable than elevated ducts or
box utilidors but their security is greater. The duct with its top cover
at ground level is a good compromise for these diverging characteristics.
-------
14-38
14.3.2.5 Corrosion and grounding. Insulated buried pipes are isolated
from the ground by dry insulation so that corrosion on the outside of the
pipe is seldom a problem. When the outer pipe or the conduit is of
metal, corrosion must be considered in cold regions as elsewhere. A
special problem arises in permafrost where grounding is complicated by the
presence of ice. The conduit may be coated and a parallel grounding wire
may be installed (e.g., zinc wire).
Internal corrosion of the pipes is controlled by the addition
of rust inhibitors to the closed circulating water systems. Steam
distribution systems have a characteristic corrosion problem in the
condensate return pipes because air enters the system and supports the
oxidation of steel pipes. One solution is to use (fiber reinforced)
plastic pipes for condensate return lines.
14.3.6 New product developments. There is a need for materials and
products to make the installation of individual service lines more
economical because they are the relatively most expensive part of the
whole network. Pre-insulated piping in lengths up to 25 m is becoming
available for this purpose, including pre-insulated T-pieces and bends.
The tube is copper or steel, the insulation is plastic foam or glass
wool, and the continuous outer jacket is HD polyethylene. The solder or
braze joints are covered with insulation shells and a heat shrink sleeve
for tightness. Installation is by direct burial in a simple trench.
Another development uses a flexible, corrugated tube, plastic
foam insulation, flexible, corrugated outer tube and extruded plastic
jacket. This "cable-pipe" is produced in long continuous lengths and
supplied on large reels. Installation is extremely fast; the pipe can
also be pulled through conduits (currently available in Europe).
A plastic insulating culvert that is becoming popular is used
as a loose fitting sleeve over bare steel pipes. Standard 2 m long
lengths are slipped over the pipes and joined with heat shrink
sleeves.
14.3.3 Gas distribution
Design and construction of gas distribution systems in arctic
and subarctic regions (regions underlain with permafrost) must deal with
-------
14-39
special problems not encountered in other areas. The basic engineering
principles governing design of gas distribution systems in temperate
climates also apply in cold regions. The special problems encountered
are discussed in the following paragraphs.
14.3.3.1 Scope. The gas distribution system consists of the piping,
supports, valves, meters, and all such necessary appurtenances from the
gas transmission line (or other primary source) to the gas piping at the
buildings.
14.3.3.2 Locations. The gas piping may be buried, installed at ground
level, or may be an overhead distribution system, depending upon the site
conditions and the overall concept and usage of the installation. The type
or types of soil at the site, depth and structure of the permafrost, water
content, surface drainage, etc., must be known. The method to be used to
preserve site stability is determined by other disciplines. The type of gas
distribution system to be designed must be consistent with the overall
concept. For example, if a thick insulating gravel pad is to be provided
for the construction site, a direct burial system may well be selected.
14.3.3.3 Direct buried systems. Where soil types and the natural
drainage patterns permit, the direct buried gas distribution system is most
desirable from standpoints of economics, security, and area utilization.
The soils must be non frost-susceptible, and seasonal moisture must readily
drain from the area. Where soils consist of frost-susceptible mateials, and
where surface water stands without draining away, the gas piping should not
be direct buried. Metal and plastic piping is used for gas distribution
systems. If piping is installed in soil which is frost-susceptible or water
saturated, the water can freeze to the pipe, forming ice anchors. A section
of piping secured between two ice anchors can fail (usually at the
connecting points) due to axial stress from further temperature reduction.
Where direct buried gas piping must cross road and traffic
lanes, the piping should be installed in a protective sleeve or culvert.
The piping within the sleeve should be provided with supports or spiders
which will position the gas pipe concentric with the sleeve. Where the
ends of the sleeves are buried, the ends should be sealed tightly to the
-------
14-40
gas pipe with flexible boots and drawbands or clamping devices. Several
types of these boots are available. Where the ends of the sleeves extend
to daylight due to area grading or to road elevation, the ends may be
left open. The sleeve or culvert should be pitched slightly to ensure
proper drainage of moisture.
The design and installation of the gas distribution system must
include provision for the expansion and contraction of the piping caused
by changes in temperatures of the soil and/or the gas. Where the system
supply is obtained from an above-ground transmission line, the product
temperature may range from 27°C to -50°C. The range of ground temperature,
of course, is less. It also changes more slowly. Flexibility may be
worked into the system layout, making use of ell-shaped and zee-shaped runs,
with properly located anchors. On long straight runs, expansion loops must
be provided. Legs of the loops should be encased in suitable resilient
material to allow space for pipe movement when required. It is recommend
that the loops be pre-stressed when installed, and adjusted so that the
loop will be in the neutral position at minimum design temperature.
Drip pockets for moisture or gas condensate accumulations with
blow-off pipes and valves are required at all low points in the system
and at the base of risers. Natural gas in cold regions may have a
sufficient water or moisture content to require dehydrating. This, of
course, is done at the well heads or at a collecting point in the gas
fields. Dehydration is accomplished with diethelyne glycol, triethelyne
glycol, or alcohol process. In each process, there is a carry-over which
collects at the system low points and must be removed periodically. For
buried piping systems, a small diameter (13 mm) return bend from the drip
leg, with a pipe extension to above-ground level, and terminated with a
blow-off valve will serve to remove accumulated liquids at the drip
collection points. The blow-off pipe should extend well above the
expected snow level, and should be protected from physical damage by a
guard post.
14.3.3.4 Ground level systems. A gas distribution system installed
just high enough above the ground to be exposed to the normal snow level
is called a ground level system. It is the most simple and economical
-------
14-41
system, but is vulnerable to damage and its use must be carefully
considered. In general, the concept can only be employed in areas
requiring a limited number of service connections and where the piping
can be routed to avoid the planned traffic patterns.
Holes for support posts should be made with a drill or soil
auger. The diameter of the hole should be approximately 8 cm larger than
the diameter of the greater axis of the support member. Depth of the
hole should extend sufficiently into the permafrost to ensure sufficient
anchor, when re-frozen, to resist the lifting force of seasonal thawing
and freezing. The required depth will depend upon the climate, the soils
and the permafrost conditions at the particular site, and should be
determined by soil experts assigned to the project. As a rule, the
required depth of penetration into the permafrost will be approximately
two-and-a-half times the depth of seasonal thaw. The void space around
the support member in the hole should be filled with a slurry prepared
from suitable water and fine soil. The water should be free of minerals
and acid so that the freeze point will not be depressed. The soil should
be a fine sandy type. The slurry should be poured or ladled into the
hole up to grade level and allowed to freeze in place. Freezing time in
the permafrost strata will vary somewhat with the temperature of the
permafrost and with the ambient temperature, but generally should be
between two and seven days.
Supports must be spaced at intervals which will prevent
excessive sag and stress in the piping. The load on the pipe consists of
the weight of the pipe, the ice and frost build-up (up to 5 em thick),
and the wind loads.
Tops of the support posts should be trimmed as required to
provide proper grading of the gas piping. The piping should be supported
on or by the posts in a manner to restrain longitudinal movement but
permit free axial movement caused by expansion and contraction of pipe.
On wooden posts, a two-piece clamp, similar to an offset pipe clamp
serves very well. Legs of the clamp may be secured to the post with
thru-bolts or lag screws. On steel posts, a wall bracket hanger may be
-------
14-42
bolted or welded in place and the pipe supported from elevis-type hangers
and hanger rods. Hanger rods should be as short as possible to minimize
pipe sway due to wind pressure.
Expansion loops must be supported in a manner to preclude
additional stress on the piping and permit proper function of the loop.
The loops should be designed and installed in such manner that the loop
stresses occur at maximum design temperature and will move toward the
un-stressed or neutral position as the pipe temperature decreases.
Expansion loops are usually considered to be on a horizontal plane.
Where it is to the advantage of the system design or layout, vertical
loops may be best. Vertical loops should be sized at least as required
for allowable stress in the piping, and may be oversized if the loop is
to be used for a pedestrian or vehicle passageway. Drip pockets and
blow-off valves should be provided at the base of the vertical legs of
the loop. Supports for the vertical loops must be designed for ioe and
wind loads as well as for piping loads.
Anchors, for controlling pipe expansion, must be properly
located at the time of design. Where possible, the anchors and loops
should be uniformly spaced to minimize unbalanced thrusts on the anchors.
Commercial type anchor elamps may be adapted to the support posts,
whether of wood or of steel, or field-fabrieated anchors may be designed.
Slip-type expansion joints or couplings are not recommended for
use in gas distribution systems in cold regions. At extremely low
temperatures, the seals of the joints harden and lose the elasticity
required for the sealing effect. The use of slip joints or couplings can
be avoided by proper use of bends, loops or offsets, eliminating an
unnecessary risk of system failure.
14.3.3.5 Overhead Distribution Systems. An overhead system, as
diseussed herein, is a system in which the gas piping is installed a
minimum of 2 m above the finished grade of maximum snow line. The
purpose of such a system would be to permit free use of all the area for
pedestrian or low vehicle (snowmobile) traffic. Higher clearances may be
provided across streets and roads for passenger cars and trucks. An
overhead system is most expensive. It is also the most vulnerable to
damage from traffic and from storms.
-------
14-43
Support for the overhead system are designed and installed as
described for ground-level systems, with due consideration given to wind
and ice loads. Where long pipe spans are required, such as at road and
street crossings, a cross-beam must be provided from which the pipe can
be suspended. The beam may be of open-web bar joist design, or wood beam
suitable for the span. Traffic signal arches of tubular construction
should also be considered.
14.4 References
1. U.S. Army CRREL/Alaska District, "Electircal Groundings of Power and
Communications Facilities for Tactical Operations in Arctic Regions".
Hanover, New Hampshire, February 1973.
2. Special Alloy Steel for Extreme Low Ambient Conditions. British
Petroleum and Westinghouse Street Corp.
3. Stockbridge, G. VI. "Overcoming Vibration in Transmission Cables".
Electrical WorkL (Dec. 26, 1925) Vol. 86, No. 26.
4. Alaska District Corps of Engineers and Alaska Electirc Light and Power
Company experience with 'Taku' winds- in the Juneau, Alaska area.
5. Gundersen, D., "Frost Protection of Buried Water and Sewer Pipes",
Draft translation TL666, U.S. Army Cold Regions Research and
Engineering Laboratory, Hanover, New Hampshire, 1978.
-------
SECTION 15
THERMAL CONSIDERATIONS
Index
15 THERMAL CONSIDERATIONS 15-1
15.1 Introduction 15-1
15.1.1 Site considerations 15-1
15.1.2 Design considerations 15-2
15.2 Freezing of Pipes 15-2
15.2.1 Freeze-protection 15-4
15.2.2 Thawing of frozen pipes 15-6
15.3 Heat Loss from Pipes 15-7
15.3.1 Pipe environment 15-8
15.3.2 Physical methods of reducing heat loss 15-12
15.4 Heat Loss Replacement 15-15
15.4.1 Fluid replacement 15-15
15.4.2 Point sources of heat 15-15
15.4.3 Pipe heat tracing 15-17
15.4.4 Electric heat tracing 15-18
15.4.5 Friction 15-21
15.5 Utility Systems 15-21
15.5.1 Thermal analysis 15-22
15.5.2 Operation 15-22
15.6 Foundations for Pipelines 15-23
15.6.1 Buried utilities in permafrost areas 15-23
15.6.2 Frost effects 15-27
15.6.3 Above-ground pipes 15-28
15.7 Materials 15-28
15.7.1 Piping materials 15-28
15.7.2 Insulation 15-30
15.7.3 Soils 15-32
15.8 Buildings and Structures 15-36
15.8.1 Thermal design 15-36
15.8.2 Foundations 15-36
-------
Index (Cont'd)
Page
15.9 Thermal Calculations 15-38
15.9.1 Steady-state pipeline solutions 15-39
15.9.2 Subsurface temperatures 15-49
15.10 Example Problems 15-58
15.11 References 15-72
-------
List of Figures
Figure Page
15-1 The Freezing of Water Pipes 15-3
15-2 Frost Penetration and Heat Loss from Bare and Insulated
Pipes Within Seasonal Frost 15-10
15-3 Methods of Insulating Buried Pipes 15-11
15-4 Relative Heat Loss from Single Pipes Insulated with
same Volume of Insulation 15-14
15-5 Relative Heat Loss from Two Pipes Insulated with same
Volume of Insulation 15-14
15-6 Thawing and Settlement of Buried Pipe Test Loop in
Ice-rich Permafrost, Bethel, Alaska 15-25
15-7 Effect of Insulation Thickness on Thaw Perturbation 15-25
15-8 Effect of Depth-of-Bury on Thaw Perturbation 15-26
15-9 Unfrozen Moisture Content in Soils 15-33
15-10 Steady-State Thermal Equations for Above-Surface Pipes 15-42
15-11 Steady-State Thermal Equations for Below-Surface Pipes 15-43
15-12 Steady-State Thermal Resistance of Various Shapes
and Bodies 15-44
15-13 Temperature Change and Freeze-up Time in Pipes 15-45
15-14 Thermal Resistance of a Hollow Cylinder 15-46
15-15 Thermal Resistance of a Soil Mass Covering a Pipe 15-47
15-16 Dimensions of a Thaw Cylinder Around a Pipe Buried
in Permafrost 15-48
15-17 Ground Temperatures Around Buried Water Pipe,
Yellowknife, N.W.T. 15-50
15-18 Sinusoidal Air and Ground Temperature Fluctuations 15-51
15-19 Ground Temperatures and Thawing Around Buried Pipes
Pipes in Permafrost 15-52
15-20 Correction Coefficient 15-55
-------
List of Tables
Table Page
15-1 Comparison of Insulation Properties of Various
Materials 15-32
15-2 List of Symbols 15-40
15-3 Thermal Conductivity of Common Materials 15-41
15-4 Some Examples of n-Factors 15-57
15-5 Some Examples of m-Factors for Ice Thickness 15-58
15-6 Conversion Factors to SI Units 15-59
-------
15-1
15 THERMAL CONSIDERATIONS
15.1 Introduction
Cold regions utility systems must function under severe
climatic conditions. Since thermal considerations are as important, or
more important than, the hydraulic and structural features, they must be
included in the selection and design of materials, components, and
processes [1,2,3]. Thermal analyses are necessary to design for freeze-
protection, foundation stability, thermal stress and economy. In this
section the major emphasis is on the thermal design of piped water and
sewer systems. Thermal aspects are discussed, and simple equations and
illustrative examples are presented solving some of the thermal problems
encountered in utility system design. Cold regions building design and
foundation considerations are only briefly considered; other references
must be consulted for detailed design information on these subjects.
15.1.1 Site considerations
Climatic and geotechnical site information is necessary for
thermal analysis and design. Adequate air temperature data, which
include the range, mean and various indices, are usually available from
nearby weather stations or from published charts and reports [4,5,6], but
the local micro-climate will modify these values (see Appendix H). Local
ground temperatures are often not available, and extrapolations are
inadvisable since they can vary significantly with the air temperature,
snow cover, vegetation, drainage, topography, and soil properties. The
most reliable approach is to obtain long term actual site measurements.
Limited data must be modified to estimate the extreme climatic conditions,
or to make allowances for surface changes resulting from construction and
development.
Geotechnical conditions are frequently highly variable within a
small area and site-specific surveys consistent with the thermal and
structural design considerations are imperative. Of primary concern is
movement and possible failure due to the freezing and thawing of the
surface. Therefore, the maximum thickness of the active layer and the
soil thermal properties and frost-susceptibility must be determined. In
-------
15-2
permafrost areas, particularly in high ice content soil, the soil survey
must extend to the maximum range of anticipated major thermal effects,
and surface conditions and drainage patterns must be noted.
15.1.2 Design considerations
The primary areas of concern in the design of utilities in cold
regions are failure of pipes due to freezing of water, thaw-settlement or
heaving of foundation soil, thermal strain and associated stress, and
economical operation.
Utility systems in cold regions are thermally designed with a
conservative safety factor, and often the worst conditions that could
occur simultaneously are considered. This is justified by:
a) simplifications and assumptions within the thermal
equations and models;
b) limited data and random nature of the climatic and physical
site conditions; and
c) variations and assumptions in the physical and thermal
properties of materials such as insulation, soils and pipes,
Although the thermal characteristics may be precisely defined, the
application and control is complicated. In practice, it is often the
unexpected or unforeseen conditions that result in damage or failure.
Thermal design must consider more than the precise thermal analysis.
Experience and judgement are also essential.
15.2 Freezing of Pipes
Freeze damage to containers of fluid, including pipes, occurs
due to the expansion of water changing to ice [7]. This imposes a
pressure on the still unfrozen liquid that can reach hundreds of
atmospheres. Failure is caused by hydrostatic pressure, not by the ice
expanding directly on the walls [8], The freezing of quiescent water in
pipes occurs in stages as illustrated in Figure 15-1(a) [9], Water must
always supercool, typically -3° to -7°C in quiescent pipes with slow
cooling, before nucleation and freezing produces dendritic ice growth.
Further cooling results in the growth of an annulus of ice inwards from
the pipe walls.
-------
15-3
PIPE CROSS SECTION
FREEZING STAGES
. .x. , Dendritic
Initial | jCe |
co (-down growth
Annular ice growth
Final
cool-down
i ii i r
TEMPERATURES
0
-4
Water temperature
Pipe wall temperature
Nucleation temperature
Time
(a) The stages in the freezing of a quiescent water pipe [9J.
Water
(b) Ice bands formed during the freezing of flowing pipe [10].
FIGURE 15-1. THE FREEZING OF WATER PIPES
Dendritic ice formation increases the start-up pressure
required to reinstate flow, particularly in small-diameter pipes and slow
fluid cooling rate, and can effectively block the pipe in much less time
than that required for the pipe to become blocked by annular growth of
ice [9].
The freezing process for fluid flowing in pipes is not simply
by annular growth and such an oversimplification can lead to false
conclusions and errors in design. Gilpin [10] observed that for flowing
pipes ice does not grow as a uniform thickness along the pipe but occurs
-------
15-4
as cyclical ice bands of a tapered flow passage (Figure 15-1(b)).
Further cooling will freeze off the narrow neck, arresting flow, and
subsequent freezing can result in pipe breaks between each ice band. No
ice formation in pipes can be safely tolerated and fluid temperatures
should not be allowed to drop below 0.5°C.
As soon as the water temperature drops to freezing, ice
formation may start somewhere in the system, usually on metal valves and
fittings. Ice plugs formed in this manner can prevent start-up or
draining of the pipes long before the entire system freezes. The
recommended design freeze-up time is only the time available before water
in an inoperative system reaches the freezing point. This time period
must be sufficient to permit repairs or to drain the system, and depends
upon the availability of maintenance personnel and equipment.
Understandably, the design freeze-up time may have to be several days in
small communities, while in larger centres the time may, with caution, be
reduced to less than one day. The shortest freeze-up time and the
largest number of freeze-ups are associated with small-diameter service
lines. The maximum safety factor freeze-up time is the time necessary
for the fluid to drop to -3°C, the nucleation temperature. No portion of
the latent heat for complete pipe freezing should be included in freeze-
up calculations. (See Figure 15-13, Example 15.9).
Gravity pipelines or open channels may also freeze by icing up.
The initial filling of water or sewer pipelines is often a critical
period with respect to freezing in this manner. Additionally, frosting
and icing may occur in the crown of uninsulated sewer lines when the heat
input is low; however, this may melt out when the flow is increased.
15.2.1 Freeze-protection
The design freeze-up time can be increased by higher operating
temperatures, increased insulation, and locating pipes where ambient
temperatures are warmer. Excess temperature increases heat loss,
introduces inefficiency, and is expensive. Utility systems that are
highly insulated are preferable, since they require less heating and
provide a longer freeze-up period. A similar argument applies to buried
systems as compared to exposed pipes. Insulation only retards freezing,
-------
15-5
and whenever ambient temperatures are below freezing, heat loss from
pipelines must be replaced. With respect to freeze-protection,
insulation can be less important than the addition of warmer water and
the maintenance of flow.
Small-diameter pipes, such as service connections, have less
specific and latent heat available and the design freeze-up time is
usually only a matter of minutes or a few hours. They are particularly
vulnerable to any interruptions in flow, and freezing usually occurs in
them first. Thawing capability is therefore mandatory for small-diameter
pipes.
Buried insulated piping will not usually significantly affect
the ground temperatures, but bare or high-temperature pipes will have a
warmed and thawed zone around them. This should not be relied upon to
increase the freeze-up time, since soil texture and moisture content vary
significantly, and the freezing temperature of moisture in soils is often
below 0°C, particularly in cohesive soils [11], Therefore, the
deliberate thawing of ground is not recommended.
Water intakes and sewer outfalls which have intermittent or low
flows and wells that have static water levels within the freezing zone
may require freeze-protection. This can be accomplished with insulation
and heat tracing or circulating raw unheated water (see Figure 3-8).
Alternatively, air pressure has been used to lower the static water level
in small-diameter pipes to below the ice or frost level when not in use
[12].
Since fire protection may be a major function of piped water
systems, freeze-protection of fire hydrants is imperative. Conventional
hydrants on buried piping within frozen ground may not drain; therefore,
they must be pumped out after use and can be filled with a non-toxic
anti-freeze mixture such as propelene glycol. In-line hydrants (see
Figures 6-22, 6-23 and 8-5) or hydrants located within manholes (see
Figure 6-24) are preferred since the water within the pipe to conven-
tional offset hydrants will be static and must be freeze-protected.
Where the demand is very low or intermittent, it may be more
economical to fill and operate a pipeline as required and drain it
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15-6
between uses, than to incorporate measures to prevent the freezing of its
contents. Such systems usually require pre-heating and post-heating of
the pipeline during an operating cycle. This principal is the basis of a
long water supply line to a small arctic community [13], and a proposed
water distribution system to buildings equipped with water storage tanks
[14], For both of these situations, uninsulated surface pipelines have
been utilized during the summer, then drained and not operated during the
winter. Storage and intermittent discharge has also been used to prevent
the icing-up of low flow or long sewer lines or outfalls [15].
Independent back-up systems should be provided for critical
components, such as circulation pumps. Systems with heating cables
should prevent freezing even if flow ceases, provided of course that
electricity to operate these is available. In cold regions, all utility
system components must be capable of being conveniently and quickly
drained. If freezing is imminent, pipelines should be manually flushed
or drained through hydrants or special fittings judiciously located at
low points in the system [16], Wherever practical, water and pressure
sewer systems should be sloped to central draining facilities. Compressed
air [12,17] or "pigs" [18] may be used to force the fluid from small-
diameter lines.
Some flexible pipe materials, such as polyethylene and small-
diameter copper lines, may not rupture upon freezing but the expansion
depends upon the manner of freezing and, at present, no pipe should be
relied upon to provide service after freeze-thaw cycles. Various methods
to prevent or limit the freeze damage of pipelines have been proposed
[7], These provide additional thermal resistance at convenient, pre-
determined locations where the hydrostatic pressure that occurs with
freezing can be dealt with by a pressure relief valve, bursting
diaphragm, expandable section, or other device, or else that short
section of pipe can be sacrified.
15.2.2 Thawing of frozen pipes
It is prudent and often mandatory to provide for the thawing of
all water and sewer pipes and wells that may freeze. Remote electrical
thawing methods which must be incorporated into the briginal design
-------
15-7
Include skin effect, impedence, and various resistance wire and commer-
cial heating cable systems. Frozen wells have been thawed by applying a
low voltage from a transformer to a copper wire located inside the drop
pipe [19], Once a small annulus is melted, the flow can be reinstated
and it will thaw the remaining ice in the pipe. A common approach to
thawing frozen small-diameter metal pipes is to pass an electrical
current from a welder or transformer through the pipe [20], This
operation is greatly facilitated if readily accessible thaw wire
connections are provided. A frozen pipe can also be thawed by passing
warm water through a small-diameter pipe which is installed on the
exterior surface of the pipe. This thaw tube system can also be used as
a carrier pipe for electric heat tracing, a return line for
recirculation, or a bypass of the main line. The capital cost of this
system is much lower than electric heat tracing but it requires manual
operation. Utilidors that incorporate pipe heat tracing can be thawed,
provided that these heating lines use an antifreeze solution or they were
drained prior to freeze-up. Exposed pipes may also be thawed with warm
air. Injection thawing with steam or hot water can be used to thaw water
and sewer lines if adequate access and room for hoses, equipment and
personnel is provided at manholes. Small-diameter water lines of any
material can also be quickly thawed by pumping warm water into a
smaller-diameter plastic hose that is inserted into the frozen pipe [21].
These thawing methods are detailed in Appendix F.
The energy required to thaw a frozen pipe is largely the heat
necessary to melt the ice. Knowing the heat that must be supplied and
the energy output of a thawing system, the time to melt the ice can be
calculated. In practice, an opening that permits a flow to commence may
be all that is necessary to thaw the remaining ice, provided that the
flushing water is warm. Long lengths may be thawed this way in stages.
In many cases, heat tracing systems are sized to thaw or reopen the line
in a reasonable length of time and not just to supply the heat loss
necessary to prevent freezing.
15.3 Heat Loss From Pipes
The thermal design must prevent the freezing of water and
wastewater within pipes or tanks that are exposed to below-freezing
-------
15-8
temperatures, and provide for economical operation. The primary and
complementary methods are by reducing and replacing heat losses. Heat
loss is proportional to the difference between the fluid and the ambient
temperatures, and the thermal resistance of the intervening materials.
Measures that provide a more favourable environment, such as buried
pipes, and measures that increase the thermal resistance, such as
insulation, will reduce the rate of heat loss. These methods do not
eliminate freezing, rather they retard it; therefore, heat losses must be
replaced by removing the cooled water before it freezes, or by heating
the fluid or the pipe surface.
Estimates of the maximum rate of heat loss are required to
determine the freeze-up time and to design heaters, circulation pumps and
heat tracing systems. Annual heat loss estimates are necessary to
determine total energy requirements and assess methods of reducing
these. Solutions to these thermal problems are outlined in Section 15.9.
15.3.1 Pipe environment
The freeze-up time and the total heat loss are dependent upon
the temperatures encountered in the pipe environment. Above-ground
piping systems must be thermally designed for the lowest expected air
temperatures, perhaps -40°C to -60°C. For reliable and economical
operation during the winter, exposed piping must be completely insulated
and usually a flow must be maintained. Some heating of water is
necessary.
Extreme air temperatures are significantly moderated by the
ground surface conditions, primarily snow cover and vegetation, and the
thermal properties of the soil. Of importance to heat loss and the
design of buried pipes are the minimum ground temperatures and the
maximum depth of freezing or thawing. Surface temperature variations are
attenuated with depth, depending upon the thermal diffusivity (thermal
inertia) and latent heat (moisture content) of the soil. While air
temperatures may have an annual range of 90°C, the temperature at a depth
of 2 m may vary from 2°C in saturated organic soils in undisturbed areas,
to as much as 25°C in exposed dry soils or rock. At a depth of 10 m,
seasonal temperature fluctuations are usually negligible. Daily air
-------
15-9
temperature fluctuations are negligible below aproximately 0.5 to 1.0 m
of bare soil or ice or 0.5 m of undisturbed snow. Air temperature
fluctuations are moderated with depth and their influence is Telt some
time later. The lag time depends upon the surface conditions and soil
thermal properties, and at a depth of 2 m may be one to five months.
Therefore, minimum ground temperatures and maximum frost penetration may
occur when the extreme winter temperatures have long passed. Frost
penetration will be greatest in rock or bare, dry soils. Undisturbed
snow cover itself may reduce the depth of frost by an amount equal to its
own thickness [22], Locating utility lines away from travelled, plowed
areas, such as at the back of lots rather than under roadways, may
significantly reduce heat loss and increase the freeze-up time, but years
with little snowfall, snowdrifting and man-induced changes must be
considered.
Conventional municipal piping can be installed below the
maximum depth of seasonal frost. In cold regions, the frost penetration
is often greater than the common pipe depths of 2 to 3 m, and may be 6 m
or more in exposed dry soil or rock. Deep frost penetration, high
groundwater, hilly terrain, rock or other factors may make it more
practical and economical to install all or portions of the utility system
within the frost zone [23,24,25]. In these cases, the degree of freeze-
protection necessary will depend upon the ground temperatures at the pipe
depth. Where pipes are only intermittently or periodically within frost,
conventional bare pipes may be adequate, provided a minimum flow can be
maintained by circulation, bleeding or consumption. Frost-proof
appurtenances, stable backfill and some heating may also be necessary.
Even in these marginal cases, insulating pipes in shallow or low
temperature areas will greatly increase the reliability of the system and
is highly desirable. Heat loss and freeze danger are significantly
reduced by insulating the pipes. This is illustrated in Figure 15-2.
Insulated pipes can be installed in shallow trenches or within
berms at the ground surface. In these cases, there is often little
thermal advantage in deep bury, but the minimum desirable cover should be
such that daily temperature fluctuations are not "felt". This is 0.5 to
-------
15-10
Nov D J F M A M J J A S O N Dec
Ground
Pipe insulated with
50mm polyurethane
FIGURE 15-2. FROST PENETRATION AND HEAT LOSS FROM BARE AND INSULATED
PIPES WITHIN SEASONAL FROST [27]
1.0 m for exposed surfaces. The minimum depth of cover is also governed
by the ability of the insulation and pipe to withstand anticipated
traffic loads, and this depth is usually approximately 1 m. Other
factors which will influence the average and local depth of bury are the
pipe grade and terrain; frost heaving problems, which are greater for
shallow pipes; and access for maintenance. In some cases, it may be
possible to balance the reduction in excavation cost with the cost of
insulation and other freeze-protection measures necessary for shallow
buried pipes within the seasonal frost zone [23,24,25].
Buried pipes within seasonal frost can be pre-insulated,
usually with polyurethane, or a layer of insulating board, usually
polystyrene, can be placed above the pipe (Figure 15-3). The latter
method uses bare pipes and fittings and the board insulation is often
less expensive; however, the installation cost will be higher and the
effectiveness of the insulation is lower than direct insulation of the
-------
15-U
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-------
15-12
Buried pipes at any depth in permafrost areas must be protected
from freezing, and pipes and appurtenances must be insulated. Deeper
pipes will experience less extreme ambient temperatures, lower maximum
rates of heat loss and longer freeze-up times. However, the heating
period will be longer and pipes installed below the seasonally thawing
active layer may require freeze-protection and heating all year. The
total annual heat loss is relatively constant with depth. The most
important function of soil above buried insulated pipes is in reducing
the ground temperature amplitude by its thermal inertia and latent heat.
The thermal resistance of the soil is often insignificant (see Example
15.3). Depth-of-bury considerations in permafrost areas are similar to
those for pipes within seasonal frost, with the possible additional
problems associated with the thawing of ice-rich permafrost.
15.3.2 Physical methods of reducing heat loss
The primary physical method of reducing heat loss is
insulation. It is impractical to prevent ground moisture, humidity or
water from pipe failures from reaching the insulation and, since moisture
content is a key factor in determining the thermal performance of
insulations, only near-hydrophobic insulations should be used. Even
these insulations will usually require some physical and moisture
protection.
Systems that are liberally insulated are generally preferred
since they require minimum heating and circulation, provide a longer
freeze-up period, and have less influence on the ground thermal regime.
An economic analysis to balance heating and insulating costs should be
performed to determine the minimum amount of insulation that is required
(see Example 15.11). Other factors, such as the freeze-up time, the
maximum rate of heat loss and practical dimensional considerations, must
also be considered in the selection of insulation thickness.
Heat loss estimates for piped systems must adequately allow for
poorly insulated or exposed sections of pipes, joints and appurtenances,
and thermal breaks such as at pipe anchors. A 150-mm gate valve has a
surface area equivalent to 1 m of bare pipe. If this valve were left
exposed it would lose as much heat as about 60 m of 150-mm pipe insulated
-------
15-13
with 50 mm of polyurethane insulation and freezing will occur at the
valve first. Therefore, the thermal resistance around appurtenances
should be 1.5 times that required around connecting pipe lengths. This
illustrates the danger of restricting thermal analysis and design to
straight sections of piping and the importance of fully insulating the
piping system.
Heat loss and the volume of materials can be reduced by
minimizing the perimeter and exposed surface area. This is most
important for above-ground pipes and facilities. Insulation is most
effective when it is placed directly around the source of heat. These
characteristics are illustrated by simple shapes in Figures 15-4 and
15-5. Where there is an air space, the thermal resistance of the pipe
air film can be quite significant and must be considered. For a single
pipe, insulation is best applied in an annulus directly around the pipe.
Heat loss from pipes in a utilidor is less than that of separate pipes
insulated with the same total volume of insulation, if the utilidor is
compact. This is often not possible. The spacing requirements for
pipes, appurtenances, installation and maintenance, particularly for
central heating lines, often make it necessary to design utilidors with
large air spaces and these utilidors will be thermally less efficient
than separately insulated pipes. Heat supplied from warm sewer pipes,-
central heating lines or heat tracing may make utilidors thermally
attractive. Pipes within utilidors may also have a longer freeze-up time
because of the larger heat source available compared to separate pipes.
This is particularly important for small-diameter pipes. Heat loss can
also be reduced and freeze-protection improved by installing one water
pipe inside of a larger one, rather than using two separate pipes. This
technique is applicable for freeze-protection of small-diameter
recirculation pipes used to maintain a flow in supply lines, or dead ends
within a water distribution system.
Heat loss can also be reduced by lowering the operating
temperature of water pipelines, but the benefits of this are only
significant where the ambient temperatures are just slightly below
freezing. The heat loss from insulated storage tanks and pipes is
-------
15-14
1.5 r
With air film 1.0 N/A
No air film 1.0 1.1
1.5 r
1.5
2.8
1.9
4.6
FIGURE 15-4,
1.5r
With air film
No air film
RELATIVE HEAT LOSS FROM SINGLE PIPES INSULATED
WITH SAME VOLUME OF INSULATION
1.0
1.0
n
Q
V.V
0.64
0.78
X
0.78
1.0
2r
0.93
1.25
With air film 0.93
No air film 1.25
0.50
0.50
0.80
0.80
FIGURE 15-5. RELATIVE HEAT LOSS FROM TWO PIPES INSULATED
WITH SAME VOLUME OF INSULATION
-------
15-15
often small compared to the energy requirements to raise the source water
to the system operating temperature. Therefore, lower operating temp-
eratures may significantly reduce energy requirements for preheating
rather than heat losses within the piping system. Because of the greater
relative reduction in heating requirements, utility systems in the sub-
arctic are'often operated nearer freezing than those in arctic regions.
Any reductions in heat loss and preheating requirements must be balanced
with the reduction in freeze-protection when systems are operated nearer
the freezing point.
15.4 Heat Loss Replacement
Heat loss cannot be completely prevented. If ambient tempera-
tures are below freezing, it is simply a matter of time before freezing
will occur unless heat is added to the fluid or it is replaced with
warmer fluid. Heat can be added either continuously or at point sources.
15.4.1 Fluid replacement
Freezing will not occur if the liquid residence time in the
pipeline is less than the time necessary for it to cool to the freezing
point. The quantity and temperature of the replacement water (i.e., the
total heat available) must be sufficient and the flow must be reliable.
Operation without additional heating is restricted to situations where
relatively warm water supplies, such as groundwater, are used and/or
where the flow rate is reliable and high, such as in some water supply
pipelines or trunk mains. Bleeding of water has been used to maintain or
enhance the flow in service lines, dead ends and intermittent flowing
pipelines but the wasting of large quantities of water can be inefficient
and lead to water supply and wastewater treatment problems. Recircula-
tion will maintain a flow and a uniform temperature within the system,
and prevent premature freezing at locations with lower than average
ambient temperatures or at poorly insulated sections. However, the water
temperature will decline unless warmer water is added or the
recirculating water is heated.
15.4.2 Point sources of heat
Water may be heated at the source, treatment plant, pumping
stations and/or along the pipeline or within distribution systems as
-------
15-16
required. Heat is commonly obtained from fuel oil fired boilers;
however, simple electric water heaters have been used where the heat
requirements are very low. The heating of water can be a practical use
for low-temperature waste heat, such as from electric power generation,
and this should always be investigated in order to reduce energy costs.
The heating capacity required to replace heat losses is based on the
maximum rate of heat loss expected; whereas annual heat loss energy
requirements are calculated from the cumulative heating index (see
Example 15,3). Where the raw water temperature is too low and must be
raised to a specified operating temperature, the required heating
capacity is determined by the maximum flow rate, and the annual energy
requirements are determined by the total water demand during the heating
period.
There must be sufficient flow within the piping system to
distribute the heat which is added. If the normal water demand is too
low or is intermittent, then bleeding or recirculation is necessary. A
minimum water temperature can be maintained within the piping system by
increasing either the flow rate or the input water temperature while
keeping the other parameters constant, or by adjusting them
simultaneously. High temperatures enhance heat loss and introduce
inefficiency. As a general rule, the temperature drop along a pipeline
should always be kept to less than 5°C, and preferably less than 2.5°C,
by insulation, higher flow rates, or intermediate heating along the
pipeline or within the system. However, there is usually little
reduction in heat loss by limiting the temperature drop to less than
0.5°C. By the same analogy, velocities greater than 0.1 m/s for 150-mm
pipes and 0.5 m/s for 50-mm pipes are of little benefit in reducing total
energy input to maintain a specified minimum water temperature. Higher
velocities, such as for pitorifice systems that require a minimum
velocity of 0.75 m/s, must be balanced with the electrical energy
requirements for pumping (see Example 15.10).
Sewer lines are generally warmer than water mains, but freezing
can occur where flows are intermittent or low. In these cases, a flush
tank can be used to periodically discharge wastewater or warm water into
-------
15-17
the sewer line (see Section 7.2.3.2). Bleeding water directly into the
sewer lines also adds heat but this practice is usually only recommended
as a temporary measure. Direct heating of wastewater is not
practised.
15.4.3 Pipe heat tracing
Heating requirements to replace heat losses and to maintain a
minimum temperature (i.e., prevent freezing) can be supplied by pipe heat
tracing systems. Such systems are more commonly used in multi-pipe
utilidors but have been used for single pipes. Heat is provided by
warming air spaces by convection, and in some cases by conduction. The
pipe heat tracing system may be part of a central heating system, or
designed only to heat a utilidor. In the former case, for above-ground
utilidors some of the high-temperature pipe insulation may have to be
removed (typically 0.25 m every 10 m) to provide enough heat to prevent
freezing at the lowest ambient temperatures. The heat source cannot be
manipulated and when the ambient temperature increases, inefficient and
undesirable overheating of the utilidor and water main occur (see Example
15.5). Freezing of pipes can result from thermal stratification in large
utilidors or the shielding of small-diameter heat tracing pipes [30],
For pipe heat tracing, low-temperature fluids, generally
between 80°C and 98°C, are much simpler to use than either steam or
high-temperature water, and the fluid mixture can be adjusted to depress
the freezing point to the lowest expected ambient temperatures. The use
of an antifreeze solution protects the heat trace piping, allows start-up
during winter and provides a means of thawing frozen pipes. The
viscosity of low freezing point glycol and water mixtures is greater than
that of water; therefore, the required pumping capacity and friction
losses will be higher. The heat transfer characteristics are also poorer
than for water. For example, a 50% mixture of glycol and water would
require a 14% increase in flow rate to achieve the same heat transfer.
Design information on these heating systems is available from the
American Society of Heating, Refrigeration and Air-Conditioning Engineers
(ASHRAE) [31,32]. It should be remembered that ethylene glycol is
toxic and cross-contamination must be prevented. Alternatively,
-------
15-18
propylene glycol, which is non-toxic, can be used. These solutions are
corrosive to zinc and they can leak through joints and pump seals that
will not leak water at the same pressures. Mechanical seal pumps should
be utilized. Some boiler manufacturers void their warranty if glycol
solutions are used. Special organic fluids can also be used instead of
water-glycol mixtures.
15.4.4 Electric heat tracing
Electric heat tracing systems are relatively easily installed
and controlled. They may be installed continuously on water and sewer
pipelines, or only at low ambient temperature, freeze-susceptible or
critical locations, such as road crossings, service connections or at
appurtenances such as fire hydrants. Because of the relatively high cost
of electrical energy, these systems are usually installed for freeze-
prevention in the event of operating upset, such as a prolonged no-flow
condition, rather than as the primary method of maintaining a minimum
operating temperature or to heat up the fluid. The capability and ease
of remote thawing is also important in many situations. The designer
must weigh these advantages against the risks, costs of electric heat
tracing systems, and alternate freeze-protection methods. They are more
attractive where the freeze-up time is short and where the lines cannot
be blown clear or drained.
A variety of electric heat tracing systems and products are
available [33]. Resistance-type cables and wires are available for
installation within pipes or for exterior tracing [34], Small-diameter
metal pipes, such as service lines, can be heated or thawed by induction
heating from an alternating current in a wire wrapped around the pipe
which induces eddy currents within the pipe [35]. Skin-effect current
tracing, which requires only one source of power and control, may have
application for long steel pipelines [36]. The most common electric heat
tracing systems used are zone-parallel and self-limiting continuous
parallel heating cables and strips [37]. They contain separate conductor
wires and resistance buss wires or conducting material in the same casing
so they produce a constant heat output per unit length, and can be
conveniently cut to the desired length. Maximum lengths are usually 75 m
-------
15-19
to 200 m, depending on the type and heating capacity, although a 400-m,
13 W/m-cable is available. One type has a carbon-filled polymeric
heating element with self-adjusting properties that decreases heat output
as the temperature increases. This cable will not burn itself out or
overheat plastic pipes, and the heat output modulates, to some extent,
with temperatures along the pipe.
For maximum heat transfer efficiency, heating cables can be
installed within pipes. The coating and joints of only a few cables,
such as mineral insulant (M.I.) resistance cable, are approved for
installation within pipes or for submerged conditions. In-line cables
are more practical for long water supply pipelines or similar
applications because valves and other such fittings must be bypassed.
They may be subject to vibration damage when fluid velocity is greater
than 1.2 m/s [38], and the cables must be removed to clean the pipes and
when some types of pipe repairs are made. Heating cables are more
conveniently and commonly located on the pipe surface. The capacity of
such heating cables should be increased by a factor of 1.5 for insulated
metal pipes [38], unless flat or wide heating strips or adequate contact
between the cable and the pipe, preferably with heat transfer cement, is
maintained. Since the thermal resistance of plastic is significant (125
times that of steel), the heat tracing capacity for plastic pipes must be
increased. Hence, Schedule 40 pipe up to 150-mm diameter and Schedule 80
pipe up to 75-mm diameter typically require 1.4 times the exterior heat
tracing capacity of a steel pipe with the same volume of insulation [39],
Exterior cables for pre-insulated pipe are commonly installed within a
raceway or conduit attached to the pipe surface, which facilitates
fabrication, installation, removal and replacement. In this
configuration, the air space and poor contact of the heating cable with
the pipe can further reduce the heat transfer efficiency, and for plastic
pipes the heat input may need to be two to six times that for a heating
cable within the pipe [40]. It is difficult to make the joints in the
exterior heating cable channel watertight, as is required for most cables
and/or their joints when used underground.
The location of the heating cable is not significant for
insulated water pipes, unless it is loose within a channel, in which case
-------
15-20
placing it on top will improve the contact and heat transfer efficiency.
For above-ground pipes, heating cables are placed in the bottom quadrant
for mechanical protection. The cable is usually located on top of buried
water pipes for easier access [41] but for partially full sewer lines the
cable is best located in the bottom quadrant.
Plastic pipes, insulation and the electric heat tracing system
itself must be protected from overheating unless the self-limiting
heating cable is used. For conventional cables, a high-temperature
thermostat cut-off is usually installed and set at about 30°C, and the
sensor is placed on the surface of the heating cable. For plastic pipes,
heating cables with an output over 12 W/m are not advisable unless
manufacturers of pipe and cables concur.
To provide freeze-protection, automatic control systems must
activate the electric heat tracing system at a set point above 0°C to
provide some lead time and allow for variances in the temperature
detection sensitivity of the thermostat and sensor. To provide
economical operation, the controls also cut off the power supply when
heating is not required. These controls are often a major cause of
malfunction and wasted energy. Mechanical thermostats with capillary
tube sensing bulbs are limited to about 5 m in length and temperature
control is only possible within a few degrees. Electronic thermostats
are much more sensitive but they are expensive. The resistance sensors
they use can be located any practical distance from the controller and
the system can be selected to maintain fluid temperatures within 0.1°C.
This type of system, which is commonly used in Greenland [38], allows the
utility system to be reliably operated at near-freezing temperatures,
which reduces or eliminates the raw water pre-heating requirements, the
utility system heat losses, and the need for recirculation. The sensors
must be located with care to provide proper control, freeze-protection,
and prevent the waste of energy. To accurately measure the fluid
temperature, they should be put in a pipe well or attached to the pipe
surface with heat transfer cement, particularly for plastic pipes. They
should be located where the lowest pipe temperatures within the section
being controlled are expected, such as at exposed windswept areas or
shallow sections.
-------
15-21
Sometimes heating cables are installed without thermostat
controls and they are manually operated. They can be left on throughout
the period when freezing can occur but this wastes energy. In some sit-
uations manually operated heating cables are used for thawing only. For
complex piping or temperature conditions, primarily industrial operations,
a single ambient temperature sensor and thermostat control have been used.
The electric heat tracing must maintain at least 0°C at the
lowest ambient temperature conditions. The minimum capacity required
must compensate for the pipe or utilidor heat loss and heat transfer
inefficiencies, and include a safety factor. In some cases, the capacity
will be increased to shorten the time required to thaw the pipe or pipes
if they become frozen. The performance of various heating cables within
a service connection utilidor are illustrated in Figure F-3. Commonly
used capacities are 8 W/m for service connections and 12 to 25 W/m for
mains. Typical installed cost for heating cables and controls is $30/m.
15.4.5 Friction
The amount of heat generated by friction depends on the flow
rate, fluid viscosity, and the pipe size and roughness. Friction heating
is negligible for smooth (new) pipes with fluid velocities less than 2
m/s, which is about the desirable upper limit for flow in pipes, but for
high fluid velocities it may be significant [42], Since this energy is
supplied by pumping, deliberately increasing the velocity (friction) is a
very inefficient method of heating. Equations for friction heat input are
presented in Figure 15-13.
15.5 Utility Systems
Many thermal considerations must be based on the characteristics
of the total utility system rather than any single pipeline, cross
section, or portion of the system. Some of these considerations include:
the efficient integration of freeze-protection of service lines and the
less freeze-susceptible mains; the identification of trunk and subdivision
pipelines that require recirculation to maintain a flow; and the decisions
related to the necessity, timing, and location and method of heat input.
These considerations must be assessed in conjunction with alternatives and
factors that influence the thermal design including: the location of
-------
15-22
pipes above or below-ground, under roadways or at the back of lots; the
depth of bury; the selection of insulation thickness, if any; and alter-
natives such as non-gravity sewer systems and non-fire flow water
systems. Some of these options are only appropriate for certain physical
or climatic conditions. Large utility systems may combine various
strategies or use different alternatives within the serviced areas as is
economical or necessary.
The thermal design must also be a part of the physical planning
and staging of development. This is particularly important for recircula-
tion systems, which must be looped, to avoid stretches of pipeline
without connections, and temporary connections or over-building (see
Sections 2.4.3 and 6.5).
15.5.1 Thermal analysis
Thermal analysis of a large water distribution system with many
loops, recirculation pumps and intermediate heating is much more complex
than the analysis at one cross-section or for a single pipeline or loop
in a recirculating system. For large systems, simultaneous hydraulic and
thermal analyses must be performed to determine the flows and water
temperatures at junctions and within each pipe length under various water
demand and ambient temperature conditions. This analysis lends itself to
computer solution [43,44], Features such as circulation pumps and check
valves require rather sophisticated hydraulic models which can be com-
bined with the analogous thermal equations to estimate flow and tempera-
ture patterns. Of particular concern is the identification of locations
or sections of the system that experience little or no flow, flow
reversals, low-temperature and short freeze-up times. The benefits and
strategic location of circulation pumps and heat input can be quickly
assessed. Large systems are usually best operated with different temp-
erature zones, and many pipes, such as trunk mains, will have sufficient
demand flow and freeze-up time that recirculation and/or heating will not
be necessary.
15.5.2 Operation
The design of the utility system, including storage,
distribution, circulation and heating, must allow for maximum operating
flexibility and adjustments, based on actual operating requirements and
-------
15-23
experience. Procedures for emergency situations such as prolonged power
failure, freeze-up, and start-up during the winter, as well as heating,
circulation, draining, thawing and other cold regions characteristics
must be clearly outlined in an operator's manual [45], Regular
surveillance, monitoring and recording of flows, heating, and fluid and
ambient ground or air temperatures must be conducted to maintain and
improve the thermal performance, and to indicate potential problems. In
some cases, soil and pipe movements may be measured.
Temperatures can be remotely measured with sensors such as
thermocouples, resistance temperature detectors (RTD) and thermistors
[46,47], The latter are commonly used because the lead wires can be of
practically unlimited length, and the off-the-shelf accuracy of 0.1°C to
0.25°C can be improved by simple calibration if desired. They are
rugged, but must be protected from moisture. A multi-cable can be used
to carry the wires from many sensors. Heat flux transducers that measure
heat loss directly are available. These various sensors can be monitored
with portable or fixed meters, or recorded on strip charts, printout or
magnetic tape. Frost penetration is indicated by a colour change in a
0.01% solution of methyl blue in a clear plastic tube inserted into a
casing in a bore hole.
15.6 Foundations for Pipelines
Frost heaving and thaw-settlement are more significant
foundation considerations than the foundation load-carrying capacity.
Frost heaving and thaw-settlement may have conflicting solutions. In
some cases, above-ground piping may be necessary but buried utilities are
usually preferred (see Section 2.5.5.4). The method of installing
utilities can be selected after careful study of the local conditions, in
conjunction with geothermal analysis of installation alternatives.
15.6.1 Buried utilities in permafrost areas
Heat loss from buried warm pipelines and thermal disturbances
resulting from their installation will cause thawing that is greater than
the natural thawing in undisturbed areas. Possible thaw-settlement of
ice-rich foundation soils requires that special attention be given to the
thermal regime and the stability of the soils and piping. The degree of
-------
15-24
concern and countermeasures depends upon the thermal sensitivity and ice
content of the permafrost. For example, at locations where the mean
annual ground temperature is just below freezing (-2°C to 0°C), it is
often impractical to prevent complete thawing of permafrost once the
surface vegetation has been disturbed. For this reason, utilities in the
discontinuous permafrost zone are usually designed for thawing and
possible settlement [48,49], In the high arctic, ground temperatures are
colder and thawing is more easily prevented. In considering buried
utilities, a distinction must be made between the relatively small and
cool water and sewer pipes, and large utilidors or high-temperature
heating pipes. With the latter, the foundations of nearby structures can
be adversely affected. It must also be kept in mind that thaw-
settlement is only significant where permafrost contains ice lenses and
excess ice content and the following considerations should not be applied
to other permafrost conditions.
Measures to prevent unacceptable settlement are: reducing the
thermal influence; replacing ice-rich foundation soils; anchoring pipes;
and freezing foundation soils [50].
The thermal influence of water and sewer pipes can be
controlled by placing insulation around or below them. Insulation will
reduce the rate of thawing and the settlement of pipes in ice-rich
permafrost. This is indicated by the results of a test loop which are
illustrated in Figure 15-6. With practical thicknesses of insulation,
the heat loss can be reduced such that it is no longer the criterion for
the practicality of installing buried utilities in ice-rich permafrost.
For large or hot conduits in warm permafrost, the insulation requirements
for complete permafrost protection tend to become excessive, but moderate
amounts of insulation result in a significant reduction in the rate of
thaw [52], Heat loss and thermal influence can be reduced by minimizing
the surface area of insulated pipes and utilidors, lowering the operating
temperature of the water pipes, and restricting the temperature of
wastewater discharges. The placement of pipes further from the depth of
maximum thaw will also reduce thawing. The relative effects of insula-
tion and depth of bury, which can be estimated for simple conditions from
equations in Section 15.9, are illustrated in Figures 15-7 and 15-8.
-------
15-25
0° C Isotherm
1 Start (November, 1968)
2 After 5 months (April, 1969)
3 After 9 months (August, 1969)
fs^f ••'•'•'.•*•.' ••'.' r ."••:'.••' ••v
1.2m
Active layer
0°C * ^J 1
Permafrost
Mean annual ground
temperature (TG)^ -0.5°C
750 Pipe -uninsulated
r
0
-20
-40
Initial location
Final location
o
r60 ^f
"5.
-80 &
-100
V't?1;* •"/•'••''•"'•'.'•. •".'•'"'•/'.'•.'•'«'•'•'.''. .'•"''•
•' ..V .Vjj • ', .. .'.'•.•» -WC? '.. '^-
Active layer
• 0°C
Permafrost
75 0 Pipe insulated
with 50 mm polyurethane
FIGURE 15-6. THAWING AND SETTLEMENT OF BURIED PIPE TEST LOOP
IN ICE-RICH PERMAFROST, BETHEL, ALASKA [51]
0 Q2 04 0.6 0.8 1.0
Mean annual ground temperature (TG) = ~3.3°C
0.2
0.4
0.6
£ 0.8
Q. 1.0
Q 1.2
1.4
1.6
1.8
2.0
..<>••
200 0 Pipe
Fluid temperature 12.8°C
Active layer
Normal active layer depth
Active layer with pipes
Insulation thickness (mm)
(kr= 0.021 Cal/m-h-°C)
Soil properties
Va= leookg/m3
kf = 1.5Cal/m-h-0C
kf = 1.9Cal/m.h.°C
W = 25%
Note' With no insulation, thaw depth under pipe = 4.3 m
FIGURE 15-7. EFFECT OF INSULATION THICKNESS ON THAW PERTURBATION [50]
-------
15-26
•5.
Q
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
0 0.2 0.4 0.6 0.8 1.0
Mean annual ground temperature (TQ) = -5°C
•i •••.••^.••••••:: ••"". "'.' ••.; • •.
•' . .•».•;.; .£)•; •;. O. ••.;.-.^.- •'. V-"-'' •.•:.•?.'••••<>;. .• •;•_
200 0 Pipe
65 mm Polyurethane insulation
-Fluid temperature (Tw) = 10°C
Soil properties
Bd= 1600 kg/m3
kf = 1.9Cal/m- h-°C
kt = 1 5Cal/m-h-°C
w= 15%
Active layer
Normal active layer depth •
T- -r -r -i
0.9 and 4.6
Active layer with pipe
>— Depth of bury of pipe Permafrost
FIGURE 15-8. EFFECT OF DEPTH-OF-BURY ON THAW PERTURBATION [50]
The effects of changes in surface conditions, groundwater movement, and
soils due to the installation of utilities and other developments are
more complex and difficult to predict. Sophisticated computer programs
can be helpful [53,54], It may be necessary to install utilities only
during periods when the air temperature is below freezing in order to
reduce the thermal disturbance, including heat input from backfill and
open excavations. Groundwater and fluid from breaks flowing along a
trench can increase thawing and, in pervious soils, impervious backfill
or cut-off walls every 50 to 200 m may be required [11,55].
Ice-rich foundation soils must be pre-thawed or replaced to the
maximum depth of expected thaw. Natural or artificial pre-thawing may be
used in the discontinuous permafrost zone, usually as part of the overall
development strategy. More commonly, soils are mechanically excavated
and replaced with compacted unfrozen soil.
Limited thawing can be tolerated if buried rigid pipes or
utilidors are anchored to the permafrost. Pile supports [2] or
-------
15-27
horizontal beams [56] can be used. These must extend beyond the maximum
thaw bulb and into the permafrost sufficiently to ensure anchorage.
These alternatives must consider the thermal disturbance created by their
installation, and frost-heaving and overburden stresses on the piping
between the supports.
Refrigeration of the foundation is possible but it is complex [52,
57], In Russia, some large utilidors with central heating networks are vent-
ilated during the winter to refreeze and cool the foundation soils that
thawed the previous summer [58], A major problem with these open utilidors
is groundwater infiltration and movement along the trench [59].
In most cases, some thawing and differential settlement must be
anticipated, and the pipe and joints should be selected with this in
mind. Brittle pipe materials such as asbestos cement must not be used.
Strong ductile pipes, such as welded steel, which can tolerate consider-
able deformation without rupture, have been successfully used [60].
15.6.2 Frost effects
Frost heaving effects must be considered for pipes and
appurtenances located within the seasonally freezing and thawing zone in
both seasonal frost and permafrost areas. The two primary methods to
reduce heaving effects on pipes are deeper burial, and over-excavation and
replacement with non frost-susceptible soils within the trench. Where
adequate backfill material is not available, it may be necessary to
construct utilities above-ground. Flexible pipes and joints may be
necessary where differential movement is expected, such as at building
connections (see Figures 7-13 and 7-14). To reduce the heaving force,
appurtenances such as fire hydrants, which protrude through the freezing
zone, can be encased in an oil and wax collar (see Figure 6-16), wrapped
with polyethylene, and/or backfilled with non frost-susceptible soil. At
Norman Wells, NWT, where frost heaving is severe, metal manholes were
fabricated in an inverted cone shape to reduce heaving forces [61].
Frost penetration significantly increases earth loading on
buried pipes [62,63] and coupled with live loads, can cause beam breaks
where pipe bedding is not uniform or the pipe has inadequate strength and
ductibility.
-------
15-28
15.6.3 Above-ground pipes
Above-ground utilities have been used where access is
necessary, where excavation or backfill material would be costly, and
where disturbance of permafrost is potentially hazardous. Piping can be
installed at the ground surface within berms, on gravel pads, or on posts
or piles. The design of piles is similar to building foundations but,
because of the light loads, except perhaps for thrust blocking, the major
design criterion is to provide sufficient anchorage to resist frost
heaving. In permafrost areas, piles of 4 to 12 m may be required, the
shorter piles being used where the active layer is thinner [64],
Unanchored surface piping must allow for ground movements due to frost
heaving. Surface drainage must be considered since ponding and erosion
can adversely affect the thermal regime, frost heaving and the foundation
soils.
15.7 Materials
Unsuitable materials are a significant cause of failure and
these often relate to their thermal performance or characteristics. Of
concern are: the thermal expansion with temperature change and freezing;
the change in thermal properties with moisture and freezing; the effects
of freeze-thaw cycles; and, the influence of temperature on strength and
durability. Other considerations are essentially similar to those in
warmer climates. Composite structures, such as pre-insulated pipes and
utilidors, and appurtenances must be compatible. Since environmental and
design conditions are varied and often opposite properties are desirable,
no material is universally applicable. General data on materials is
available from manufacturers, but comparisons are often difficult and
those characteristics which are important to cold regions may not be
emphasized or available.
15.7.1 Piping materials
Although some northern engineers prefer certain types of pipe,
virtually every type of pipe used for watermains and sewers elsewhere has
been used in cold regions. The generally desirable qualities of northern
piping materials are: low thermal conductivity, low thermal expansion co-
efficient, high thermal inertia; resistance to freezing damage and freeze-
-------
15-29
thaw cycles; fire resistance; ease of heating and thawing; convenience in
applying insulation; low sensitivity to deformation of foundation soils;
good transportability; and low weight. As not all of these character-
istics are available in one type of pipe, the selection must be based
upon the best material for the specific job, keeping in mind that it is
desirable to standardize for maintenance purposes. The characteristics
and properties of pipe materials are presented in Appendix A.
Some pipe materials, such as wood stave pipe, which were used
in the past have largely been supplanted by modern plastics. The ability
to withstand movement due to thaw-settlement or frost heaving is a major
reason for the use of ductile iron and steel pipes. Plastic pipe is
attractive because of its light weight, which eases shipping and
installation. For service connections, copper is very popular, in part
because it can be electrically thawed.
The thermal conductivity of metal pipes is insignificant and
although the thermal resistance of polyethylene is about 125 times
greater than that of steel, its insulating value is usually not very
important when pipes are insulated (see Example 15.1). The heat capacity
of the pipe is not usually considered in temperature change and freeze-up
calculations but materials with low heat capacity, such as aluminum, would
be an advantage for pipelines designed for intermittent flow [15],
Thermal stress and strain result from changes in the pipe
temperature. The worst conditions often occur during the installation
and initial filling of pipes, or if the lines are drained and allowed to
cool when the ambient temperatures are at a minimum. The maximum ambient
temperature range is naturally higher for above-ground piping. The
calculations required are: the change in length (Al = 1'u'AT); stress
(a = E'u'AT); and the load (P = A»a), where: 1 = length of pipe;
Al = change in length; u = coefficient of thermal expansion; AT = change
in temperature; E = Young's modules; o = stress; P = load; and A = cross-
section area of pipe (see Example 15.12).
For rigid pipes with high coefficients of thermal expansion,
such as metal and fibreglass, it is impractical to restrain movement
because the load would be very high. Movement can be accommodated by
flexible joints, expansion joints, expansion loops, or by allowing pipe
-------
15-30
movement. In-line expansion compensation mechanisms do not perform as well
at low temperatures and when coated with ice. In these conditions, free-
flexing bellows which have no sliding parts generally provide better
service [65],
The expansion of flexible pipe, such as plastics, is greater than
for rigid pipes, but their low tensile strength makes it possible to restrain
this type of pipe to eliminate movement. This can be done by: fixing the
pipe to stationary anchors; encasing the pipe within rigid insulation or
casing, provided that the insulation shear strength and bond are adequate;
or by burial, provided that the soil friction and weight are adequate.
15.7.2 Insulation
Insulation of piping and structures in cold regions is usually
necessary. The appropriate type and thickness must be selected. The
thickness may be determined from economic analysis (see Example 15-11),
or other considerations such as freeze-up time or building comfort.
Common insulating materials are plastics, minerals and natural fibers, or
composite materials. For design purposes, the structural and thermal
properties for the worst conditions should be used. These conditions
occur after aging, compaction, saturation and freeze-thaw cycles. Other
selection considerations are ease of installation, vapour transmission,
burning characteristics, and susceptibility to damage by vandals,
animals, chemicals and the environment.
The insulating value of a material depends more or less direct-
ly on the volume of entrapped gas in the material. If the material
becomes wet and the voids filled with water, the insulating properties
are lost since the thermal resistance of air is about 25 times that of
water and 100 times that of ice. This is the case when peat moss or
similar materials are used around underground pipes [66], In the past,
the lack of a near-hydrophobic insulation made the design of piping in
moist environments very difficult [11], and is a major reason for the
development of above-ground utilidors [3], The advent and availability
of rigid closed-cell plastic foam insulations with low thermal conducti-
vity and high resistance to water absorption has dramatically influenced
northern utility systems. They have limitations and knowledge of their
properties is essential.
-------
15-31
Polyurethane foam is used extensively in cold regions to
insulate pipes and storage tanks, and is also used in some buildings and
foundations. Urethane will bond to most materials. Piping or other
components can be pre-insulated or polyurethane can be applied on-site
from the raw chemicals, which are about l/30th the final volume. Field
applications are restricted by climatic conditions, and the density and
thermal conductivity will often be higher than values attainable under
factory conditions (see Section 5.2.2). The foam must be protected from
ultraviolet radiation during shipping and use. Only a metal skin has
proven effective to prevent "aging" (the loss of entrapped heavy gas),
which increases the thermal conductivity by about 30% above the theoret-
ical minimum value [67], Depending upon the formulation, urethanes can
have a higher flame-spread rating than other building materials, but they
are combustible and a flame-protective barrier is usually required by
building insurers and some building codes. If ignited, plastic foams
release smoke and toxic gases. Densities over 100 kg/m-^ are
essentially impermeable, but lighter foams, which are better insulators,
require coatings to prevent water absorption, since freeze-thaw cycles of
the moisture can lead to deterioration of the insulation.
Extruded polystyrene, particularly the high density products
(50 kg/m^), suffer the least from moisture absorption and freeze-thaw
[68], but the outer 5 mm of unprotected buried insulation should be
disregarded in thermal analyses. Molded polystyrene will absorb some
moisture and should not be used in moist conditions. Polystyrene is
available in board stock or beads. The former has been extensively used
to reduce frost penetration. Beads are useful for filling voids in
utilidors while retaining easy access to pipes (see Figure 8-1B).
Although the thermal conductivity of polystyrene is higher than
urethanes, the volumetric cost is usually less (Table 15-1).
Glass fiber batt insulation is the most common building
insulation, primarily because it is fire-resistant and relatively
inexpensive. Its insulating value is significantly reduced when wet, and
is reduced by half if 8% by volume is water. For this reason, glass
fiber should not be used underground but may be considered wherever dry
conditions can be ensured. Cellular glass is very water-resistant but is
-------
15-32
TABLE 15-1. COMPARISON OF INSULATION PROPERTIES OF VARIOUS MATERIALS
Material
Polyurethane
New
Aged
High Strength
Expanded Polystyrene
Molded Polystyrene
Sulfur Foam
Insulating Concrete
Glass Fiber
Glass Foam
Vermiculite
Sawdust (dry)
Fine Grained Soil
Moisture 10% (Frozen)
Moisture 307. (Frozen)
Coarse Grained Soil
Moisture 5% (Frozen)
Moisture 15% (Frozen)
Water
Ice
Thermal
Conductivity (0
Cal/h-m-°C
0.014
0.02
0.07
0.025-0-030
0.026-0.033
0.036
0.09 - 0.52
0.03 — 0 . 04 5
0.05
0.06
0.05-0.08
0.9 (0.9)
1.5 (2.0)
1.4 (1.0)
1.8 (2.6)
0.50
1.90
Density
kg/m3
30
30
65
15-45
15-30
175
300-1500
2 5—55
150-200
200
150-250
1600
1600
1750
1750
1000
900
Compressive Effect of Relative
Strength at Moisture Content (w) Volumetric
5% Deflection on Thermal Cost
kg/m2 x 10"1* Conductivity (k)
2 Negligable 4 to 6.5
2 Negligable
7 Nil
2-3 Negligable 3.5
0.7 - 1.8 Absorption, w= 32 max. 2
3.2 Absorption, w= 2% max.
7-60 Non-repellent
w= 8%, k= 0.06
7 (Ultimate) Nil
Deteriorates
Deteriorates
Increases
Increases
(1) Cal/h-m-°C x 1.1622 = W/m-k
seldom used because it is brittle, difficult to work with, and deteriorates
with freeze-thaw cycles. Lightweight insulating concrete made with poly-
styrene beads, pumice or expanded shale can be formulated with relatively
high strength and thermal resistance. It can be poured in place around
piping but should be protected from moisture to prevent freeze-thaw deter-
ioration.
Many other insulating materials, including new products such as
sulphur foam and UREA-Formaldehyde, may also find specific applications
in cold regions engineering.
15.7.3 Soils
Soil thermal properties are discussed in many reports [69,70,71,
72,73,74] and in this manual they are only considered in general terms.
These include the thermal conductivity, volumetric heat capacity, thermal
diffusivity, latent heat and strength. These properties are necessary to
-------
15-33
determine the depth of seasonal freezing or thawing, and variation in
ground temperatures due to surface temperature fluctuations. They are
also important in determining heat loss from buried pipes and in
foundation design. In the field, soil composition can vary drastically
within short distances and profile, and may be altered by development.
Thermal properties derived from limited samples and indirect measurements
must be used with caution. Satisfactory estimates may often be obtained
by assuming the worst soil properties or conditions.
In general, the soil thermal properties relate to the moisture
content, the state (frozen or thawed), the size and shape of the mineral
particles, and the temperature. When water changes to ice, its thermal
conductivity increases by a factor of 4; its volumetric specific heat
decreases by one-half; and it releases enough heat to change the
temperature of an equal volume of rock by 150°C. Water content plays a
prominent role in soil thermal considerations because of this behaviour
[73]. For fine-grained soils (silts and clays), not all the soil
moisture freezes at 0°C, although for practical purposes all moisture is
frozen by -20°C (Figure 15-9). In this range, particularly 0°C to -5°C,
thermal-related properties are in transition.
-10
Clay
Pleistocene clay
Clayey silt with some clay
Silty sand with some clay
Sand
-20
-30
Negative soil temperature (°C)
FIGURE 15-9. UNFROZEN MOISTURE CONTENT IN SOILS [72]
-------
15-34
The specific heat capacity of a substance is the ratio of the
heat capacity of a substance to the heat capacity of water and is therefore
dimensionless. The volumetric heat capacity (C) is a measure of the heat
required to raise the temperature of a unit volume of material by one degree.
The value for soils is the aggregate of the constituents, water and mineral,
and since these are relatively consistant, the soil heat capacity is deter-
mined by their proportion. The only unknown is the moisture content.
For thawed soil:
Ct - YS Cms + Cmw _w_ (15-1)
|~
L
and for frozen soil:
Cf = YS Cms + Cmi
100
where: C = volumetric heat capacity (J/m3«°c),
Ys = dry unit weight (kg/m^),
Cm = mass heat capacity (J/kg*°C),
Cms = 837 J/kg'°C for dry soil (mineral matter),
Cmw = 4184 J/kg'°C for water,
Cmi = 2092 J/kg'°C for ice.
The soil thermal conductivity (k) is a measure of the rate at
which heat moves through a medium under a unit thermal gradient. A
satisfactory formula is not available in terms of the aggregate of the
constituents to account for thermal conductivity. Values can be
determined by direct measurement, but they are more commonly approximated
from tables or graphs based on the soil type and moisture content (see
Appendix C). Thermal conductivity increases with soil moisture, density
and on freezing. For example, undisturbed dry sand is several times
better an insulator than moist compacted sand, while the thermal
conductivity of silt is about half that of coarse-grained soil and
several times greater than rock.
Thermal diffusivity (a) is a measure of the rate at which a
temperature change spreads through a material and is:
a = k/C (m2/s) (15-3)
-------
15-35
Temperature propagation is most rapid in materials with high thermal
conductivity and low heat capacity, such as rock, dry soils or
insulations. Soils of higher moisture content have decreasing thermal
diffusivity; therefore, saturated soils will change temperature slower
than dry soils.
The volumetric latent heat of fusion (L) is the heat which is
required to thaw (or is liberated on freezing) a unit volume of soil. It
depends on the moisture content of the soil and is:
L =7S (-!*-} (J/m3) (15-4)
Vioo/
Where: L = volumetric latent heat of fusion of soil (J/m3),
Lw = volumetric latent heat of fusion of water,
= 334720 J/kg.
The latent heat of soil is important in calculating the depth of freezing
or thawing.
The physical properties of frozen soil depend almost entirely
on the amount of ice the soil contains and the soil temperature,
particularly when it is just below freezing ("plastic frozen") and
unfrozen moisture is present. In terms of stability, the soil
temperature is usually more important than the load. Settlement
associated with the thawing of frozen soil can be estimated from the
moisture content and the dry unit weight of the soil [75], If the rate
of thawing and generation of water exceeds the soil drainage capacity,
excess pore pressures are generated, the bearing capacity is drastically
reduced, and failure can occur [76],
Frost heaving results primarily from the siphoning or vapour
movement of groundwater (moisture) to a freezing front where it forms ice
lenses. Only a minor amount of the heaving is caused by the volume
expansion of freezing water. The potentially damaging mechanisms are the
heaving and progressive frost-jacking of objects within the freezing
zone, as well as settlement and softening (loss of bearing capacity) of
the soil upon thawing. The frost-susceptibility of soils is primarily a
function of the size of the soil particles but a uniformly accepted
criterion does not exist. Non-cohesive materials such as crushed rock,
-------
15-36
gravel and sand are non frost-susceptible. Soils with greater than 3%
passing sieve size 200 (0.074 mm) should be treated as frost-susceptible
unless laboratory testing proves otherwise.
15.8 Building and Structures
The functional and structural design of buildings and
structures that are part of cold regions utility systems are similar to
conventional requirements. Many design aspects are covered by local or
national codes. Northern characteristics, such as transportation
requirements or the lack of skilled tradesmen, must be considered to
ensure appropriate and economic design. Building thermal design
considerations differ from temperate areas only in degree, while
foundations in permafrost areas require unique solutions.
15.8.1 Thermal design
The shape of buildings, tanks or other structures cannot always
be adjusted, but the designer should bear in mind that compact cubes or
cylinders have the lowest heat loss of all practical shapes. Windows
have very high heat loss, even with double or triple thermopane, and they
should only be installed where they are of significant benefit or
required. The insulation thickness requirements can be determined from
an economic analysis. For building walls, a minimum of 150 mm of glass
fiber or equivalent insulation should be used. Air infiltration, which
usually accounts for a significant portion of heating requirements,
should be reduced through design and good workmanship. A double door
entrance reduces air and heat loss. Humidity can be a severe problem and
hazard in utility buildings particularly those with open aerated water
surfaces, but these can sometimes be covered or enclosed. Vapour
barriers must be meticulously installed to prevent air leakage and
moisture penetration into the insulation.
Buildings are often prefabricated to some degree. Walk-in type
freezers with urethane foam-insulated metal panel walls have been used
for small pumphouses or truck water fill points (see Figure 6-4).
15.8.2 Foundations
Utility buildings and structures such as treatment plants and
storage tanks can be very heavy and deformations must be limited because
-------
15-37
of the piping and equipment. Conventional bearing and frost heave
considerations apply in non-permafrost areas. In permafrost areas, the
foundation must be designed for the thermal and mechanical interaction
due to construction and operation, and allowances must be made for
physical and thermal changes which may occur as a result of future
development or other operations. The primary concerns are: the possible
settlement due to thawing of ice-rich permafrost; frost heaving; and, for
heavy structures on warm permafrost, creep must also be considered. The
two general methods of permafrost foundation design are: the active
method, which uses the foundation in the thawing or thawed state; and the
passive method, which maintains the permafrost. The applicable strategy
depends upon the thermal and physical characteristics of the structure
and the permafrost. In thaw-unstable soils, the most commonly used
approach is to ensure preservation of the permafrost [77],
Active designs may entail: the replacement of ice-rich soils;
natural or artificial thawing and compaction prior to construction
(usually only in permeable, thaw-stable soils); and, allowing thawing
during construction and use, provided that the estimated settlement is
acceptable. These solutions are recommended when bedrock or stable
soils are at shallow depths; where settlement is tolerable; in
discontinuous permafrost where soils are plastic frozen (warmer than
-1.5°C); or if the retention of the frozen state is not technically
feasible, such as under a reservoir.
Passive designs include: putting buildings on piles to isolate
them from the ground; building on top of gravel pads that may include
foam insulation to reduce foundation heating or be ventilated with ducts
through which cold winter air is forced or naturally flows; or the
foundation can be cooled either by artificial refrigeration or the use of
thermal piles.
The design of bases and foundations in permafrost is not dealt
with in detail in this manual, and other references [64,70,71,72,73,74,77,
78,79] and specialists with a thorough understanding of geotechnical and
thermal geotechnics should be consulted.
-------
15-38
15.9 Thermal Calculations
Unfortunatly, many of the thermal problems that are encountered
in practice either do not have exact mathematical solutions or other
complexities make precise solutions impossible. The second-order dif-
ferential equation which describes the conduction of heat, the diffusion
equation, succumbs to a limited number of closed-form solutions, and these
generally relate to geometrically simple boundaries, relatively homogenous
materials, and steady state conditions [80]. However, such solutions are
useful since their explicit nature allows for relatively easy numerical
computation and encourages quantitative insight into thermal problems.
The analytical thermal equations presented in this Section imply
severe idealizations. The analyst must assess their applicability for
particular problems and use the results as a guide to engineering design.
The analyst is advised to consider various models and a range of values
for physical and temperature conditions. More accurate results are
obtained when reliable data is available. In many cases, the analyst must
be content with approximate solutions and it will be necessary to assume a
large safety factor and/or the worst conditions to arrive at conservative
estimates.
It should be noted that boundary temperatures in the field vary
continuously with both random and periodic components, and are often a
result of very complex heat exchange effects. The materials encountered
in practice frequently represent rather poor approximations of homogenous,
isotropic media. Soil, for example, is a complex, multi-phase, heter-
ogenous medium, the behaviour of which is further complicated by the water
component, which undergoes phase transitions in the temperature regime of
concern. Some of these physical and thermal complexities may be taken
into account by using strictly numerical techniques to solve the appro-
priate differential equations [53,54,81]. Even the most sophisticated
computer programs still incorporate many restrictive approximations,
particularly with respect to determining the ground surface temperatures
and the near-surface ground thermal regime [81]. Further, because of the
associated high manpower and computing costs, such numerical methods may
often only be utilized for design projects of a considerable magnitude.
-------
15-iiy
Portions of this section, including time-independent,
steady-state problems of heat flow in this section are adapted from
Thornton [82]. As well, equations to calculate ground temperatures and
depth of freezing and thawing are included. The symbols used are defined
in Table 15-2, and the thermal conductivity of some common materials are
presented in Table 15-3. Solutions to a number of utility system
problems are presented to illustrate the computational procedures and
typical results.
15.9.1 Steady-state pipeline solutions
Figure 15-10 deals with heat flow from: a bare pipe; an
insulated pipe; a single pipe in an insulated box; and, a utilidor
carrying multiple pipes. In each case, some of the major approximations,
in addition to the implied time-independent steady-state assumptions, are
indicated. Some comments intended to facilitate application of the
formulae are also included. Where applicable, expressions are presented
for relevant thermal resistance, rates of heat flow and insulation
thicknesses.
Figure 15-11 gives similar information for uninsulated and
insulated buried pipes. In each of these two cases, the presence of
thawed ground around the pipe is considered, and formulae are included
which indicate the dimensions of the resulting thaw cylinder.
Figure 15-12 contains expressions for the thermal resistance of
various shapes and bodies from which heat loss can be calculated.
Formulae are given in Figure 15-13 for estimating the temperature drop
(or gain) along a pipeline system, and simple expressions relating to
freeze-up times under no-flow conditions are included.
To ease the process of computation, numerical values for
certain variables in some of the calculations may be read directly from
Figures 15-14, 15-15 and 15-16. These curves summarize information
pertaining to the thermal resistance of a hollow cylinder (insulation
shell or pipe), the thermal resistance of a soil mass covering a pipe,
and the physical dimensions of a thaw cylinder around a pipe buried in
permafrost.
Steady-state thermal influences in isotropic, homogenous soils
can be summed and geometric modifications and approximations can be made
-------
15-40
TABLE 15-2. LIST OF SYMBOLS
List of Symbols
List of Subscripts
A = Amplitude
A = Thaw factor = T* arccosh Hp/rp
B =/irCf/k-p
c =/H2 - r2, m (ft)
Cm = Mass heat capacity, J/kg« (BTU/lb-°F)
C = Volumetric heat capacity, J/m3-K (BTU/ft3-°F)
d & t = Thickness, M (ft)
D = Scaling parameter, m (ft)
E = Young's modulus, kg/m2 (lb/ft2)
F = arccosh (H/r)
h = Thermal film coefficient (or surface conductance),
W/m2-K (BTU/h-ft2'°F)
H = Depth of bury, m (ft)
I = Freezing or thawing index, °K-s (°F'h)
k = Thermal conductivity, W/m-K (BTU/h-ff°F)
£ = Length, m (ft)
L = Volumetric latent heat, J/m3 (BTU/ft3)
p = Period, S(h)
P = Perimeter (mean), m (ft)
q = Fluid flow rate, m3/s (ft3/s)
Q = Rate of heat loss per unit longitudinal length,
W/m (BTU/ffh)
r = Radius, m (ft)
R = Thermal resistance of unit logitudinal length,
K-m/K (h-ff°F/BTU)
t = Time, s(h)
T = Temperature, K (°F)
T* = (TX - TG)/(TO - TG)
u = Coefficient of thermal expansion, m/m-K - m/m-K
(ft/ff°F)
w = Moisture content by dry weight, %
V = Velocity, m/s (ft/h)
x = Depth
X = Depth to freezing (0°C) plane, m (ft)
a = Thermal diffusivity, m2/s (ft2/h)
Y = Unit weight (density), kg/m3 (lb/ft3)
a, y, X = Coefficients in modified Berggren equation
A - refers to Air
C - refers to Conduit
E - refers to Exterior casing
(of utilidor)
f - refers to Frozen soil
g - refers to Ground freezing
index
G - refers to Ground
h - refers to Heating index
I - refers to Insulation
j - denotes 1,2,3
L - refers to Thermal lining
(of utilidor)
m - refers to Mean
0 - refers to (Zero) Freezing
point of water
P - refers to Pipe
S - refers to Soil
t - refers to Thawed soil
U - refers to Utilidor
W - refers to Water (fluid)
within a pipe
x - refers to Depth
Z - refers to Zone of thaw
-------
15-41
TABLE 15-3. THERMAL CONDUCTIVITIES OF COMMON MATERIALS
Material
Air, no convection (0°C)
Air film, outside, 24 km.h
wind (per air film)
Air film, inside (per air
film)
Polyurethane foam
Polystyrene foam
Rock wool, glass wool
Snow, new, loose
Snow, on ground
Snow, drifted and compacted
Ice at -40°C
Ice at 0°C
Water (0°C)
Peat, dry
Peat, thawed, 80% moisture
Peat, frozen, 80% ice
Peat, pressed, moist
Clay, dry
Clay, thawed, saturated (20%)
Clay, frozen, saturated (20%)
Sand, dry
Sand, thawed, saturated (10%)
Sand, frozen, saturated (10%)
Rock typical
Wood, plywood, dry
Wood, fir or pine, dry
Wood, maple or oad, dry
Insulating concrete (varies)
Concrete
Asphalt
Polyethelene, high density
PVC
Asbestos cement
Wood stave (varies)
Steel
Ductile iron
Aluminium
Copper
Unit
Weight
(dry)
kg/m3
32
30
55
85
300
500
900
900
1000
250
250
250
1140
1700
1700
1700
2000
2000
2000
2500
600
500
700
200 to
1500
2500
2000
950
1400
1900
7500
7500
2700
8800
Specific
Heat
Capacity
0.24
0.4
0.3
0.2
0.5
0.5
0.5
0.5
0.5
1.0
0.5
0.32
0.22
0.4
0.22
0.42
0.32
0.19
0.29
0.24
0.20
0.65
0.6
0.5
0.16
0.54
0.25
0.12
0.21
0.1
Thermal Conductivity
cal/ Cal/ W/m-K BTU/
cm-s-°C m-h-°C ffh-°F
0.057
2.10
0.58
0.058
0.086
0.095
0.20
0.54
1.7
6.36
5.28
1.40
0.17
0.33
0.42
1.8
2.2
3.9
5.0
2.8
7.8
9.7
5.2
0.42
0.28
0.42
0.17 to
0.40
4.2
1.72
0.86
0.44
1.56
0.62
103
125
490
900
0.020
0.75
0.20
0.021
0.031
0.034
0.07
0.20
0.6
2.29
1.90
0.50
0.06
0.12
0.15
0.60
0.8
1.4
1.8
1.0
2.8
3.5
1.9
0.15
0.10
0.15
0.16 to
0.50
1.5
0.62
0.31
0.16
0.56
0.22
37
45
175
325
0.024
0.86
0.24
0.024
0.036
0.040
0.08
0.23
0.7
2.66
2.21
0.58
0.07
0.14
1.73
0.70
0.9
1.6
2.1
1.1
3.2
4.1
2.2
0.17
0.12
0.17
0.07 to
0.60
1.7
0.72
0.36
0.19
0.65
0.26
43
50
200
375
0.014
0.50
0.14
0.014
0.020
0.023
0.05
0.13
0.4
1.54
1.28
0.34
0.04
0.08
1.0
0.40
0.5
1.0
1.2
0.06
1.9
2.4
1.3
0.10
0.07
0.10
0.04 to
0.35
1.0
0.42
0.21
0.11
0.38
0.15
25
30
115
220
(1) Values are representative
properties.
of materials but most materials have a variation in thermal
-------
Sketch
Assumptions
Thprmal
Resistance
Rate of
Heat Loss
Insulation
Thickness
(qiven Q)
Comments
(a) Bare Pipe
Air Film -v -^
fr* ^\--~PlpeRp
NSa^ogSX
^ Water Film
RW
Thin walled pipe (i e rp « 2 r^)
Rwis negligible Rp^ RA
Rp = (rp- rw)/ (rp+ rw) -a- kp
C-r T \0 25
%_i) w
RA = 1/27j-rPhA
7 5
N = 0.23Btu/h-ft4-°F"
W = /12.5V -I- 1 for V= miles/ h
N = 1.12J/s-mr-°C?
W = / 0.56 V + 1 for V = m / s
Q = (TW-TA)/RC
N/A
Often, for metal pipes, Rpmay be neglected.
If Rpis significant, the expression above
for hAwill generate an overestimate of Q.
If TA * Tw switch TA and Tw in the
expression for hA.
(b) Insulated Pipe
/*"" "^N.
/"x^^^s^X TA
(vA)
R -S^C^^;/
All thermal resistances but that of the
insulation are neglected.
RC = Rl = ' 2^k,
Ki^p)A if <^2'?
Or given ^ / rp and kj; read off
Rjfrom graph
0= (TW-TA)/R,
r,-rp= rp{exP[277k,(Tw~TA)/Q]-1}
= Trkj(Tw- TA)Q if riS2rp
Or given Rtand kj, read off rj / rpfrom graph
The neglected thermal resistances given
in (a) may be included if desjred.
Estimate a value for the insulation
surface temperature and calculate
hA and Rfl Interate
(c) Single Pipe in a Box
/-Thermal Lining
'A F-~.
Insulated or »/~^ ^- Exterior Casing
-"Bare"- ^Q)^ ' RE
TU — :
•"• T PL™J
.^ r- PE ^Ir-'E
Convection ensures the temperature inside the utilidor,
Ty, is uniform. Utilidor air films neglected.
Calculate R& the thermal resistance of the interior
conduit by
using (b) if insulated or using (a) if bare and replacing TA
in the formula for r^ by an estimate for Tu ( s Tw)
RL= tL/PLkL RE= tE/PEkE
RU — RL+ RE
R = Rc+ RU
T (TW/RC) + (Tfl/Fy
'U - (1/RJ-+ (1/RJ
If bare pipe, iterate TU
Q = (Tw-Tfl)/R
Obtain REand Rcas above
tu^L^Q^1-^-^]
If bare interior pipe, iterate Ty, Rcand
hence tL
The value of hfl, and hence RA, is fairly insensitive to the
choice of TU, and so one iteration on TU is usually
sufficient. Often REmay be neglected. Similar
calculational procedure may be performed for pipes and
utilidors of different cross-section.
(d) Multiple Pipe Utilidor
/-T, ...
TA TU/^Vf"R1 /~R3
(@J >^
Rut
Same as (c).
Calculate R for each pipe as in (c) to get Rj,
(J= 1,2,3, )
Calculate Ryas in (c)
T _ j
-------
(a) Bare, No Thaw
(b) Bare, With Thaw Zone
(c) Insulated, No Thaw
(d) Insulated, With Thaw Zone
Sketch
IB I
'HP-
(x,y)
Assumptions
Neglect all thermal resistances
except that of the soil.
Same as (a), but accounting for the different
conductivities of thawed and frozen soil
Neglecting all thermal resistances except those of the soil
and insulation Outer surface of insulation assumed to be
isothermal, r, - rp 2rp
Or Given HP/rp,
Read off arccosh (Hp/rp) from Figure 15.15
Hz = c coth A rz = c csch A
Or. Given A;
Read off Hz/c and rz/c from Figure 15.16
(if A ^ 0.2, use Hz/c = rz/c = 1 /A)
R,,R, andRs(= Rt + Rt) as given m(d),
but with r, replaced by rp.
RI as given in Figure 15.10 (b)
Rs as given in (a), but with rp replaced by r,
T T Ri (Tw - TG)
h - Tw R + R
For known Tw, TG, and Rs, the minimum insulation
thickness to prevent thaw (le. T, = To) is given by:
"i = ~r T ^s
'r> — In
R! asgiven in Figure 15.10 (b)
Tw, T', c, Hz, rzandRsasin(b)butwithrP
replaced by r, and using-
A = T' [ arccosh (HP/rP) + 2jr k, R, ]
Ri(Tw-TG)
T, = Tw -
(kt/k,)RI
Also-
R, = [ arccosh (HP/r,) - arccosh (Hz/rz ] / 2 n k,
= [ln(HP-rz/r,-Hz)]/2wkt ifHzs2rz
RI = [ arccosh (Hz/rz) ] / 2 TT k,
= [ In (2 Hz/rz ) ] / 2 TT k, if Hz 5 2rz
Or. Given Hp/r, and Hz/rz; Read off arccosh
(HP/r,)and arccosh (Hz/rz) from Figure 15.15.
Ul
I
U>
Rate of
Heat Loss
Q =
Tw - T0
Q =
where R =
arccosh (Hp/rp)
2 irk,
Q =
Q =
T' •
Tw ~
Or To evaluate Rg, use Figure 15.15
(kt/k,)R,
Insulation
Thickness
For no thawing outside the insulation the minimum
insulation thickness is given by:
N/A
N/A
Or: Given R| and k,;
Read off r|/rpfrom Figure 15.14
Given Hz or rz calculate Hz/c or rz/c and use Figure
15.16 to evaluate A. Then use Figure 15.15 for
arccosh (HP/r,)
R i = [ (A/T') + arccosh (HP/r,) ] / 2 TT k,
r, - rp as in (c) but with R, replaced by R, from above.
Comments
For calculations of heat loss
when there is a temperature
gradient in the soil and Hp>2rp,
TGmaybe replaced byTHp,the
undisturbed ground temperature at
the pipe axis depth. For an upper
limit on heat toss use ks = k,,
otherwise use ks = (k, + k,) / 2.
The thawed zone is a circle in cross-section
May be used to approximate (d) if k, = k, and/or rz = r,,
and thaw zone parameters are not required. Use ks = k(
or ks = (k,+ k,)/2asin(a).
Often the above expressions for Rt, R, and Rs
are not required
FIGURE 15-11. STEADY STATE THERMAL EQUATIONS FOR BELOW SURFACE PIPES [adapted from 82]
-------
15-44
Condition
Square
insulation
Rectangular
insulation
Eccentric
cylindrical
insulation
Two buried
pipes
Buried
rectangular
duct
Surface
thermal
resistance
Composite
wall
Sketch
^4 1
k-a— 1
(3> „ j
i /ol\
si K ri; \
V ^x 7
„ ^ ^TG _
7%i«?^T
K3) 0i
UP^
-. .,- TG „
| :*^£^StfR£»:v£"
H---. ••••.- ..-.•• ••-••-• •
-L la %s
P
b
_._.A_.1._
TG h0 H0
•?:ivr:^'-v^;£;*';' t •••'""•
•k
Ks
k1 k2
^^
h'^
-.-X.|--X2—
Thermal resistance
n ^ In 1 nft
R - a^k, ln 1°8 2rp
P 1 In/ ^ °S^
R 27tk lnUr ^1
b/a S b/a S b/a S
1.00 008290 200 000373 400 697x10"6
125 003963 225 000170 500 301x1Q-7
150 001781 250 000078 i i
175 000816 300 000016 oo 0
< 7(r2+r,)2 - s2 + V(r2-r,)2-s2
R - — — In
2Kki Vfr2*r1)2-s2- V(r2-r,)2-s2
1 ,rrrn-h ri2 + r22-s2
2TTk, 2r,- r2
Where H,s3r, , H2*3r2 and ps3(r, + r2)
l 2H1 - In 2H2 - I /(hi+h2)2+P2
r, r2 ln/(h h)2+n2
P i
R^ 2Ttko
, /(h,+h2)2-fp2
V (h^hg)2* p2
r r 1°
In 2H1 - In 2H2 I l /(hi*h2)2*P2 I
'n n ln r2 [^(h.-h,)2.^ J
Rl-'= 2TVkc
|n 2H2 = In/(h1+h2)2 +P2
r! V^-h^+p2
n 1 m a5H
/ h \ ' 025 075
ks(57 + J|) b -a
Surface thermal resistance between ground
and air can be approximated as the
equivalent thickness of the underlying soil
equal to
H - KS
H°"^
R « J-+ J- +^l + ^2
R h, h0 k, + k2
FIGURE 15-12. STEADY-STATE THERMAL RESISTANCE OF VARIOUS SHAPES AND
BODIES [81]
-------
15-45
Heat Loss and Temperature Drop
in a Fluid Flowing Through a Pipe
Freeze-Up Time For a Full Pipe
Under No-Flow Conditions (V = o)
Length,
Fluid mean velocity,
».
Fluid flow rate,
q(=V-irrw«)
rw-*-[Q] Fluid volumetric heat capacity, C Latent heat, L ~\1
yj—-----
- Input fluid temperature, T,
I
Output fluid
temperature, T2
Exterior (ambient) temperature, TA
Thermal resistance of unit length, R
Comments: The above sketch is schematic. R and TA appearing in these equations can be replaced by the
thermal resistance and corresponding exterior temperature for any shape or configuration.
D = irrw V-C-R
Calculate^ or T2,Given R, T, or T2, TA
TI= TA + (T2-TA)/ exp(-//D)
= TA + (T2 - TA) / (1 +1/D) if^/D z 0.1
T2-TA+(T1-TA)exp(-i/D)
Calculate R, Given T,, T2, TA
R =£/?rrw*.V- C •ln[(T2-TA)/(T1-TA)]
= /(T, - TA) / TT rw2 • V • C (T, - T2) if/fD == 0.1
Calculate V, Given T,, T2, TA, R
V =//7rrw'.R- C •Intfo-TiJ/O", -TA)]
= M -TA)/7rrwz.V.C(T, -T2) if|/D==0.1
Calculate Heat Loss (Q), Given T1 or T2 , TA, V, R
Q = (D/RX^-T^I -exp(-//D)]
=(//R)0"i-TA)
= D/R (T2-TA)
Calculate Friction Heating, Given V, f
Q, = F-r^-V-f
Where: Q, = BTU / h • ft
F = 0.2515BTU/ft"
r = ft
V = ft/h
f = friction head loss, ft / ft length
Not significant for V < 2.3x10" ft / h
or Q{ = J / s • m
F = 3.074x10< J/m4
r = m
V = m/s
f = friction head loss, m / m length
Not significant for V a 2 m / s
Freeze-Up Times; Given R, T, , TA
Assume that thermal resistance of the ice, as it forms,
and the heat capacity of the pipe and insulation are
negligible.
Design Time (Recommended)
tD = Time for the fluid temperature to drop to the
freezing point.
= TT-r^-R- C •ln[(T1-TA)/(T0-TA)]
tor[{T1-T0)/(T1-TA)]<0.1
Safety Factor Time
tSF = Time for the fluid to drop to the nucleation
temperature. Same as tD but with To
replaced by -3°C.
Complete Freezing Time
tF = Time for the fluid at freezing point, 0°C,
to completely freeze solid.
= 7r-rw2-R-L-/(T0-TA)
Calculate R, Given a No-Flow Time
Design Choice
RD= time/TT-r^. C -InfCT,-TA)/(TO-TA)]
Minimum Resistance
RSF = same as RD but with TQ replaced
by -3°C.
FIGURE 15-13. TEMPERATURE DROP AND FREEZE-UP TIME IN PIPES
[adapted from 82]
-------
15-46
Thermal Conduct.v.ty (k)" 3.0 Cal/h-m-'C
0
l-l 1-2 1-3 1-4 1-5 1-6 IT 1-8 1-9 2-0 2-25 2-5 2T5 3-0 3-5 4-0 4-5 5-0
FIGURE 15-14. THERMAL RESISTANCE OF A HOLLOW CYLINDER
-------
THERMAL RESISTANCE h-m-°C/Cdl
ro
01
01
O
o
o
Ol
o
8
§
Ui
I
ro
01
CO
H
>
2!
n
M
CO
X <°
> o
CO
CO
o
o
M
O
W
00
IS3
01
o
al
CO
o
(0
o
-------
4-0
3-0
N
§ 2-0
N
I
1-0
1-0
2-0
3-0
4-0
5-0
-P~
00
FIGURE 15-16. DIMENSIONS OF A THAW CYLINDER AROUND A PIPE BURIED IN PERMAFROST [82]
-------
15-49
to these basic equations. For example, a layered soil can be represented
by an "effective" soil thickness with the same total thermal resistance.
as the layered soil.
When pipes are buried below the influence of short-term air
temperature fluctuations, the ground temperatures around the pipeline
resemble a slowly changing series of steady-state conditions [58], This
is ilustrated in Figure 15-17. The heat loss from deeply buried pipes
can be calculated from steady-state equations for a cylinder of material
around a pipe if the fluid temperature and the soil temperature at a
known distance from the pipe are measured, and the soil and insulation
thermal conductivities are known [84,85,86], Heat loss from deep pipes
can also be conveniently estimated by replacing the ground surface
temperature in the steady-state equations with the undisturbed ground
temperature at the pipe depth [24] (see Example 15.3).
Heat loss from a buried pipe over a time period can be
calculated from the Heating Index during that period (see Example 15.3).
This is the sum of the degree seconds (k*s) between the pipe fluid
temperature and the ambient temperature. Thus:
Heat Loss = Heating Index (J) (15-5)
Thermal Resistance
a 2^((Pipe Temperature - Ambient Temperature) (15-6)
Thermal Resistance
15.9.2 Subsurface temperatures
Ground temperatures are determined by: the air (or ground
surface) temperatures and their variations; the thermal influence of
nearby water bodies, buried pipelines or other structures; heat flow from
the interior of the earth; and the soil thermal properties. There are a
multitude of mathematical solutions to geothermal problems which
incorporate various simplifications but are useful and accurate enough for
many foundation problems. Many of these solutions are of a specialized
nature and application, and are not presented in this manual.
Steady-state ground temperatures beneath a building or water
body can be calculated from equations [87], geometric [88], or graphical
solutions [89], The effect of a sudden change in the ground surface
-------
15-50
Ground temperature (°C)
-6-4-20 24 6 8 10
Oi i i i i i
100
i
&
200
300
Mean temperature around pipe
Mean temperature of undisturbed ground
1
Mean annual air temperature —5.5°C
FIGURE 15-17. GROUND TEMPERATURES AROUND BURIED WATER PIPE AT
YELLOWKNIFE, NWT, CANADA [66]
temperature can be simply calculated when the influence of latent heat is
not involved or assumed negligible [70,80], A similar graphical solution
is available for the temperature field surrounding a cylinder (pipe) which
undergoes a sudden change in temperature [90],
Air or ground temperatures can often be reasonably estimated as
a sinusoidal temperature fluctuation which repeats itself daily and
annually. This temperature pattern is attenuated with depth and, in a
homogeneous material (soil) with no change of state, the temperature at
any depth and time can be calculated from the equations in Figure 15-18.
This simple solution indicates the trends found in actual ground
temperatures but, in practice, they can be significantly modified by the
effects of latent heat, differences in frozen and thawed soil thermal
thermal properties (conductivity and diffusivity), non-homogenous
materials, and non-symmetrical surface temperatures because of seasonal
snow cover, vegetation, and other local climatic influences. No
analytical closed-form solution which considers these effects exists, but
numerical computer solutions which can take some of these•factors into
account are readily available (for example [52,53,54,81]).
15.9.2.1 Temperature and thawing around a buried pipe. Steady-state
temperatures around a pipe (real or equivalent) can be easily determined
from equations, but there is no analytical solution for a sinusoidal
-------
S
-------
^. Active layer (A)
TG To
Tx=TGMT0-TG)e'B(x-A)
for x^A
(forx=o IE: below pipe)
B =
^K^"
kf-p
calculate from steady state equations
in Figure 15-11.
Steady state ground
temperatures with pipe
TX = TG+ (T0-TG) e"B(x"A) + (T,-TG)-
Hp+£i+c\
Hp+rrc;
In
Ul
I
01
t-0
for i = 1, 2,3 ... F = arccosh
=« In 2Hp/rt for Hp ^ 2rl
*_ VTG
T =
Maximum ground temperatures
in permafrost beneath active layer
Estimate of thawing beneath pipe
FIGURE 15-19. GROUND TEMPERATURES AND THAWING AROUND BURIED PIPES IN PERMAFROST
-------
15-53
15.9.2.2 Depth of freezing or thawing. The depth of freezing or thawing
of soil or the ice thickness on water bodies is best obtained by field
measurements, but they can be estimated using one of the many analytical
solutions in the literature [71,80,90,91,92,93], Because of the assumptions
necessary in these analytical solutions, such as a step change in surface
temperature and/or neglecting the soil temperature changes, they
generally overestimate the maximum freezing isotherm depths for the given
conditions and are, therefore, useful in engineering computations. They
are generally Neuman or Stephan-based solutions which have the form:
X = m.fl7= m./t (15-7)
^/ O A/
where: X = depth of freezing or thawing,
m = coefficient of proportionality,
Ig = ground surface freezing (If) or thawing (It) index (K»s),
t = freezing or thawing period (s).
The following equations incorporate various assumptions, but are
accurate and handy for specific conditions.
(15-8)
2k • I
X , I J _ (15-9)
L + C Tm- To + if]
X-fcdV,
Vw v
/2k • I /
V 8l
01 T -'--'-
^kl - Ig ~ 2kx
L2
C-I \
- 1d (15-10)
8L - t / (15-n)
(15-12)
-------
15-54
where: k = thermal conductivity of the material above the freezing
isotherm, kf for frost penetration and kt for thawing
calculations,
L = volumetric latent heat of the material undergoing phase
change (Equation 15-4),
C = volumetric heat capacity of the material above the freezing
isotherm, Cf or Ct (Equations 15-1, 15-2),
Tm = mean annual site temperature,
T0 = freezing point,
d = thickness of layer of material,
X = a correction coefficient which takes into consideration the
effect of temperature change in the soil, and primarily
accounts for the volumetric specific heat effects. It is a
function of two parameters, the thermal ratio (a) and the
fusion parameter (y), and is determined from Figure 15-20.
CT - T \ CT - T V t
o _ V m o/ _ V m o/
a - T - -
s e
T = I /t, surface freezing or thawing index divided by the
s g
length of that period.
Subscripts f and t refer to freezing and thawing, and subscript
1 and 2 refer to the surface layer and the underlying material.
Equation 15-8 is the Stephan solution for a homogenous material
with a step change in surface temperature. This is modified in Equation
15-9 to account for the temperature change in the freezing or thawing
soil. Equation 15-10 is a two-layer solution of the Stephan equation
which is useful for calculations involving snow cover, a gravel pad or a
board of thermal insulation, in which case the surface layer has no
latent heat and the equation is simplified. Equation 15-11 is a close
approximation of the Neuman solution when the ground temperatures are
near-freezing [92], Equation 15-12, the modified Berggren equation, is
perhaps the most commonly used solution for soils [93].
-------
15-55
0.0
1.0
0.9
0.8
0.7
o
o
I 0.6
o
Q>
O
O 0.5
0.4
0.3
Fusion parameter p
0.1 0.2 0.3 0.4
0.5
FIGURE 15-20. CORRECTION COEFFICIENT
It should be noted that, with high moisture content soils the X
coefficient approaches unity, the simple Stephan solution. In northern
climates where the mean annual temperature is near or below freezing, the
thermal ratio approaches zero and the X coefficient is greater than
0.9.
In very dry soils, the soil warming or cooling can be
significant and should be included [94]. Multi-layered soil systems can
be solved by determining that portion of the surface freezing or thawing
index required to penetrate each layer. The sum of the thicknesses of
the frozen or thawed layers whose indices equal the total index is equal
to the depth of freeze or thaw. The partial freezing or thawing index to
penetrate the ntn layers is [95]:
-------
15-56
/n-1
I = ^ • dn Z R + Rn 1 (15-13)
^n I —
2 y i 2
where: In = the partial freezing or thawing index required to penetrate
the nth layer,
Ln = volumetric latent heat in the ntn layer;
dn = thickness of the nt" layer,
X = the coefficient based on the weighted average values for
U down to and including the nth layer,
n-1
2—i R = the sum of the thermal resistances of the layers
above the nth ]_averj anc[
Rn _ dn; the thermal resistance of the nch layer.
The solution of multi-layered systems is facilitated by tabular
arrangement of the intermediate values. The penetration into the last
layer must be solved by trial and error to match the total freezing or
thawing index at the site (see Example 15.13).
It is necessary to determine the temperature condition at the
ground surface to determine subsurface thermal effects, including the
depth of freezing and thawing. Since air temperatures are readily
available, but surface temperatures are not, a correlation factor which
combines the effects of radiation, and convective and conductive heat
exchange at the air-ground surface is used:
Ig = n • Ia (15-14)
where: Ig = ground surface freezing or thawing index,
Ia = air freezing or thawing index, and
n = n-factor, ratio of the surface and air temperature indices.
The n-factor is very significant in analytical ground thermal
considerations [96]. It is highly variable and is usually estimated from
published observations such as those values suggested in Table 15-4.
-------
15-57
TABLE 15-4. SOME EXAMPLES OF n-FACTORS [97]
n-FACTORS
SURFACE
THAWING
FREEZING
COMMENTS
Snow
Pavement free of snow & ice
Sand and gravel
Turf
Spruce
Spruce trees, brush
Above site, cleared,
moss surface
Stripped, mineral soil
surface
Spruce
Willows
Weeds
Gravel fill slope
Gravel road
Concrete road
Asphalt road
White painted surface
Peat bales on road
Dark gravel
0.35
0.37
0.73
1.72
1.74
0.76
1.44
1.15
1.0
0.9
2.0 0.9
1.0 0.5
to 0.53 0.55 to 0.9
to 0.41 0.28
to 0.78 0.25
to 1.26 0.33
0.76
0.82
0.86
1.38 0.7
1.99
2.03
,1.96,2.70
,0.98,1.25
,1.72,2.28
,1.40,1.73
General application
General application
General application
General application
Thompson,
Fairbanks
Fairbanks
Fairbanks
Manitoba
, Alaska
, Alaska
, Alaska
Inuvik, NWT
Fairbanks
Fairbanks
Fairbanks
Fairbanks
Fairbanks
Fairbanks
Fairbanks
, Alaska
, Alaska
, Alaska
, Alaska
, Alaska
, Aslaska
, Alaska
Ice thickness on water bodies may be estimated from the
previous depth of freezing equations or from Equations 15-7 with the m
values in Table 15-5 (see Example 15.14). Snow cover has a
significant insulating effect and can significantly reduce the maximum
ice thickness. The ice formation can be greater th calculated if the
weight of snow or the lowering of the water level causes cracks in the
ice and water overflows onto the surface. This water is drawn into
the snow and the mixture refreezes and bonds to th original ice. This
snow ice appears white or frosty, whereas pure wat ice appears clear
or black.
-------
15-58
TABLE 15-5. SOME EXAMPLES OF m-FACTORS FOR ICE THICKNESS [98]
m-Factor
? x 10~5
Conditions
10.4 - 11.0
9.3
8.1 - 9.3
6.7 - 7.5
4.6 - 5.8
2.3 - 4.6
Practical maximum for ice not covered with snow
Windy lakes with no snow
Medium-sized lakes with moderate snow cover
Rivers with moderate flow
River with snow
Small river with rapid flow
* x 8625 = ft/0F?'h?
x 60 = m/°C?*hJ
15.10 Example Problems
The following example problems are presented to indicate the
application of thermal equations to solve some of the thermal problems
encountered in utility system design.
Various units of measure are still in common usage and this can
lead to some confusion and errors. Most of the equations presented in
this section can be utilized with any system of units as long as the
units are consistent. The analyst is encouraged to work in S.I. units
and Table 15-6 lists conversion factors to S.I. units. Example problems
in metric, S.I. and British units are presented.
-------
15-59
TABLE 15-6. CONVERSIONS TO SI UNITS
To convert from:
Area
circular mil
foot2
inch2
Dens i ty
pound/ foot3
pound/inch3
Energy and Work
kilo joules (kJ)
British Thermal Unit (BTU)
calorie (cal)
Calorie (Real or Cal)
kilowatt - hour
horsepower - hour
Flow Rate
foot3/second
foot3/minute
foot3/hour
Imperial gallons/second
Imperial gallons/hour
U.S. gallons/second
U.S gallons/hour
litres/second
Force
kilogram - force
pound - force
Heat
Heat capacity
BTU/lb-°F
cal/g-°C
Cal/kg-°C
k J/kg-K
Latent heat
BTU/lb
cal/g
Cal/kg
kJ/kg
Thermal conductivity
BTU/h-ft-°F
BTU-in/h-ft2-°F
cal/s-cm-°C
Cal/h-m-°C
Thermal resistance
h-ft: °F/BTU
s-cm- °C/cal
h-m- °C/Cal
Length
inch
foot
mile
Mass
ounce
pound
ton (short, 2000 Ib)
ton (metric)
litre (water, 4°C )
to
m2
m2
m2
kg/m3
kg/m3
J
J
J
J
J
J
mf/s
3 /
m Is
m3/s
m3/s
m3/s
m3/s
m3/s
m3/s
N
N
J/kg-K
J/kg-R
J/kg-K
J/kg-K
J/kg
J/kg
J/kg
J/kg
W/m-K
W/m-K
W/m-K
W/m-K
K-m/W
K-m/W
K-m/W
m
m
m
kg
kg
kg
kg
kg
Multiply by:
5.0671 x 10~10
0.0929
6.4516 x 10"1*
16.018
27680.
0.001
1054.4
4.184
4184
3.6 x 106
2.6845 x 106
0.028317
4.7195 x KT1*
7.8658 x 10~6
4.5459 x 10" 3
1.26275 x 10~6
3.785 x 10" 3
1.0514 x 10-6
0.001
9.80665
4.4482
4184
4184
4184
0.001
2324.6
4184
4184
0.001
1.7296
0.14413
418.4
1.1622
0.5782
2.390 x 10"3
0.8604
0.0254
0.3048
1609.3
0.02835
0.45359
907.18
1000
1
To convert from:
Power
BTU/second
BTU/hour
cal/second
cal/hour
Cal/second
Cal/hour
foot pounds force/second
horse power (550 ft-lb/s)
horse power (electric)
Joules/second
Pressure or Stress
atmosphere
bar
foot of water
inch of water (4°C)
inch of mercury (0°C)
pound-force/inch2 (psi)
kilogram- force/ centimeter2
kilogram- force/meter2
kilo pascals (kPa)
pascal
Temperature
Temperature interval
°C
°F
Temperature
°C
°F
Veloci ty
foot/second
foot/hour
miles/second
miles/hour
kilometers /hour
Viscoci ty
Dynamic
pascal -second
centipoise
pound-force-seconds/foot2
Kinematic
centistoke
foot2/second
Volume
acre-foot
barrel (oil)
foot3
gallon (U.S.)
gallon (Imperial)
litre
yard3
to
W
w
w
w
w
w
w
w
w
w
N/m2
N/m2
N/m2
N/m2
N/m2
N/m2
N/m2
N/m2
N/m2
N/m2
K
K
K
K
m/s
m/s
m/s
m/s
m/s
N-s/m2
N-s/m2
N-s/m2
m2/s
m2/s
m3
m3
m3
m3
m3
m3
m3
Multiply by:
1054.4
0.2929
4.184
1.1622 x 10~3
4184
1.1622
1.3558
745.70
746
1
101325
100000
2989
249.08
3386.4
6894.8
98066.5
98.066
1000
1
1
5/9 or 0.5556
°C + 273
(°F + 459.7) 5/
0.3048
8.4667 X 10 "*
1609.3
0.44704
0.27778
1
0.001
47.880
1.0 x 10"6
0.0929
1233.5
0.15899
0.028317
3.7854 x 10~3
4.5459 x 10 "3
1000
0.76455
-------
15-60
EXAMPLE 15.1
Calculate the rate of heat loss (per unit length) from a plastic pipe of outside diameter 166 mm and inside
diamter 136 mm whose thermal conductivity is 0.36 W/m • K and is encased in 50 mm of polyurethane foam of
thermal conductivity 0.023 W/m • K when the pipe contains water at 5°C and the above ground pipe is exposed
to an air temperature of -40°C and the wind speed is 25 km/h (7 mis).
SOLUTION:
r, = (166/2) + 50 • = 133, rp = 166/2 = 83
From Figure 15-14
for rt/rp = 133/83= 1.6
and kt = 0.023; Read off:
R, = 3.3m-K/W
Assume RP = negligible
and RA = negligible
Q = 5 ' <-4°) =13.6
3.3
= 14W/m
From Equations in Figure 15-10(a), (b)
In (133/83)
Rr =
RP =
2'77-0.023
In (83/68)
2.77-0.36
= 3.26 m - K/W
= 0.09 m • K/W
Estimate the insulation surface temperature (Ts) to be
at -35°C, a value close to TA.
• Note: W = J/s, N = 1 .12, W = 0.56, V = 7m/s
h
r_35
=1.12[ o
0.25
_
/(0.56. 7)+ 1=6.15
RA = 11(2 - 77 • 0.133 • 6.15) = 0.20 m • K/W
0.20
Ts = -40+ [5-(-40)]
0.20+3.26+0.09
= -37.5°C
Further interation gives Ts = -37°C
and RA = 0.22 m • K/W
Rc = 0.22 + 0.09 + 3.26 = 3.57 m • K/W
Q = 5-(-40) =12.6 = 13 W/m
3.57
NOTE:
The thermal resistance of the pipe and the air film could be neglected in this case of a well insulated pipe. If
there was no wind, Ts = -35°C, RA = QA* and Q = 11.9 W/m.
EXAMPLE 15.2
Calculate the rate of heat loss (per unit length) for the pipe in Example 15.1 if the pipe is buried at a depth of 1 .22m
in soil with a thermal conductivity of 2.0 W/m • K when the fluid temperature is 5°C and the (steady state)
ground surface temperature is -40°C.
SOLUTION:
From Example 15.1 : RP = 0.09 m • K/W and R! = 3.26 m • K/W
FromFigure 15-16forHP/rP= 1.22/0.133 = 9.17; obtain Rs or since HP >2rP from Figure 15-11 (a):
RS =
Rc = 0.09 + 3.26 + 0.23= 3.58 m • K/W
Q = 5 ~ (~40) =12.6 = 13 W/m
NOTE:
The thermal resistance of the soil is relatively small compared to that of the insulated pipe and in this case it
could have been neglected. In practice, the main effect of the soil is to dampen out the extreme temperature
fluctuations (daily or annually) at the ground surface and a mean ground surface temperature of -40°C is
unrealisticallv low for buried heat loss calculations (See Example 15.3).
-------
15-61
EXAMPLE 15.3
Calculate the annual heat loss and the maximum rate of heat loss (per unit length) for the pipes in Examples
15.1 and 15.2 when the ambient temperatures (typical of Barrow, Alaska) are:
Mean Monthly Temperatures (°C)
Mean
Annual JFMAMJJASOND
Air -12.8 -28.4 -24.9 -24.0 -16.8 -11.7 -1.2 4.5 2.6 -0.2 -8.8 -15.2 -21.4
Depth of
1.22m -9.7 -14.0 -15.0 -15.0 -13.8 -10.4 -8.0 -4.9 -2.8 -2.8 -3.1 -6.7 -10.0
Minimum air temperature =-50.0°C
Minimum mean daily ground temperature at 1.22m = -17.8°C
SOLUTION:
Heating Index = 2 (Tw - TA) for period when TA 2 T0 (When there is a risk of freezing)
ForAir: JA = 2[5 - (-12.8)] + [5 - (-28.4)] + (for each month)
= 199.6°C • months = 146000 K • h
For Depth of 1.22 m: I1-22 = 2 [ 5 - (-14.0) ] + [ 5 - (- 15.0) ] + (for each month)
= 166.5°C • months = 122000 K • h
For an above ground pipe:
From Example 15.1: Rc = 3.57 m • K/W = 3.57 s • m • K/J
Annual heat loss = 146000 (60 • 60) / 3.57 = 1.47 • 10" J /m
Maximum rate of heat loss = [ 5 - (-50.0)1/3.57 = 15.4 W/m
and for a buried pipe:
From Example 15.2: Rc = 3.60 m • K/W = 3.60 s • m • K/J
Annual heat loss = 122000 (60 • 60) / 3.60 = 1.22 • 10* J/m
Maximum rate of heat loss = [ 5- (-17.8) ] / 3.60 = 6.3 W/m
NOTE 1:
The annual heat loss from the above ground pipe is only slightly higher than a pipe buried in permafrost;
thowever, the maximum rate of heat loss (and freeze-up risk) is much higher. The relative differences become
greater in warmer areas, particularly in non-permafrost conditions. In the extreme case, the pipe may be
located below the maximum frost penetration therefore heating and freezing risk are nil.
NOTE 2:
The use of the mean daily (or even hourly) temperatures would result in a more precise (and lower) estimate of
the Heating Index, but this is seldom warranted.
-------
15-62
EXAMPLE 15.4
Calculate the interior temperature and rate of heat loss (per unit length) from the plywood box sketched below
which contains a 6-inch nominal diameter, Class 150 asbestos cement pipe. Assume that there is free
convection, radiation is negligible and that there is no air exchange (leakage) from the box. Temperatures and
dimensions are shown below.
SOLUTION:
PipeO.D. =7.17"
I.D. = 5.85"
kp = 0.375 BTU/ft-h
kL = 0.02 BTU/ft-h
kE = 0.075 BTU/ft-h
rP = 3.58" = 0.298 ft
rw = 2.98" = 0.243 ft
rP - rw = 0.055 ft
and
rp + rw = 0.541 ft
From Figure 15-10(c):
Estimate Ty to be +35°F, a value between -50°F and +50°F.
RP =
0.055
0.541 '-IT- 0.375
hA =
= 0.086 h • ft • °F/BTU
= 0.613 h-ft2-°F/BTU
RA = 1 / (2 • IT • 0.298 • 0.613) = 0.872 h • ft • T/BTU
and Rc = 0.086 + 0.872 = 0.959 = 0.96 h • ft • °F/BTU
PE = 4 (2.0 + 0.75/12) = 8.25 ft
RE= (0.75/12) / 8.25-0.075 = 0.101 h-tt-°F/BTU
PL = 4 (2.0-3/12) = 7.0 ft
RL = (3/12) / 7 • 0.02 = 1.786 h • ft • T/BTU
RU = 0.101 +1.786 = 1.887 = 1.89 h • ft • "F/BTU
= _gp/M6)-(50/1:8gL =1630p
u (1/0.96)+ (1/1.89)
Interate (Use this new value of TD and repeat the calculation)
0.298
= 0.75lvft2'°F/BTU
RA = 1 / (2 • TT • 0.298 • 0.75) = 0.712 h • ft • °F/BTU
and Rc = 0.086 + 0.712 = 0.798 = 0.80 h • ft • °F/BTU
T = (50/0.80)-(50/1.89) = 203<>F
U (1/0.80)+ (1/1.89)
Another interation gives a value of TU = 19.7 °F
Hence Ty = 20 °F
andQ =
50 - (-50)
37BTU/h'ft
-Plywood
2'0"
IE3"
\
TA = -5
Polystyrene
2'0"-
O.«0 + 1.89
orQ =^0^50)_ .37BTU/h.tt
NOTE:
If the same volume of polystyrene were placed in a annulus around the pipe, the radius would be 0.79 ft and
the rate of heat loss would be 13 BTU /h • ft.
-------
15-63
EXAMPLE 15.5
The same configuration as Example 15.4, but including a 2 inch OD High Temperature Water (HTW) pipe
at 250°F encased within 1.5 inches of asbestos fibre of thermal conductivity 0.04 BTU /h • ft • °F.
SOLUTION:
From Example 15.4: RtJ •= 1.89 BTU/h • ft • °F;
RP = 0.086 BTU/h • ft • °F (for water conduit)
The thermal resistance of the HTW pipe and the air film adjacent to the insulation are neglected. The thermal
resistance of the HTW pipe insulation can be determined from Figure 15-15 or by equation:
rj = (1 +1.5) /12 = 0.208 ft; rp = 1.0 /12 = 0.083 ft
Rz= Rl = ; -3.65h.ft-F/BTU
2* IT' 0.04
From Figure 1 5-1 0(d):
Assume TU = 35°F since then part of the calculation has already been done in Example 1 5.4.
So: RT = 0.96 h • ft • °F/BTU
2 Tj / Rj = 250 / 3.65 + 50 / 0.96 = 1 20.6 BTU / h • ft • °F
and 21 /Rj = 1/3.65 + 1 /0.96 = 1.32 BTU/h -ft- °F
120.6 + (-50/1 .89)
= 51 C
1.32 + (1/1 .89)
(Further interation gives RI = 1 .66 and TU = 51 .3 °F)
250 — S1
For the HTW pipe: Q2 = - = 54.5 = 54 BTU/h • ft
3.65
For the Water Pipe: Q, = 5° ~ 51 - 0.6 -OBTU/h-ft
1 .66
For the Box: QB = 51 ~ = 53.7 = 54 BTU /h • ft
NOTE 1 :
If the air film of the HTW pipe insulation had been included the temperature at the surface of the insulation
must also be estimated and an interative analysis performed. This results in an interior temperature of
approximately TU - 45°F, which is quite close to the previous simple analysis.
NOTE 2:
If the HTW pipe ceases to f |