tc terrain mapping guidelines
TRANSCRIPT
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TableofContents
1.0 INTRODUCTION .................................................................................................................................. 5
2. 0 SURFICIAL GEOLOGY MAPPING .................................................................................................... 6
2.1 Description of Surficial Geology Mapping ......................................................................................... 6
2.2 Example of Surficial Geology Mapping in Northern Canada ............................................................. 6
3.0 ENGINEERING TERRAIN ANALYSIS .............................................................................................. 7
3.1 General Description of Engineering Terrain Analysis and Mapping .................................................. 7
3.2 Preliminary Engineering Terrain Analysis and Mapping (Level 1D) ................................................. 7
3.3 Detailed Engineering Terrain Analysis and Mapping (Level 2D) ...................................................... 7
3.4 Example of Preliminary and Detailed Engineering Terrain Analysis (Level 1D and Level 2D) from
Northern Canada ....................................................................................................................................... 8
3.5 Example of Preliminary and Detailed Engineering Terrain Analysis (Level 1D and 2D) for Pipeline
Projects in Alberta and BC........................................................................................................................ 9
4.0 SELECTION ENGINEERING TERRAIN MAPPING SYSTEM FOR A PIPELINE PROJECT ...... 11
4.1 Existing Government Surficial Geology Mapping System ............................................................... 11
4.2 Consider the Terrain Issues Relevant to the Area of Study .............................................................. 11
4.3 Consider the Terrain Mapping Experience of the Government Reviewers of the Pipeline Project .. 11
5 0 ENGINEERING TERRAIN ANALYSIS AND ITS CONTRIBUTION TO DETERMINING KEY
ITEMS FOR PIPELINE PLANNING, CONSTRUCTION AND OPERATION ...................................... 12
5.1 Pipeline Right of Way Continuous Terrain Information for Engineering ........................................ 12
5.2 Pipeline Right of Way Ditch Properties ............................................................................................ 12
5.3 Level 1D and Level 2DTerrain Mapping Describes Land at Pipeline Infrastructure Sites .............. 12
5.4 Location of Geohazards .................................................................................................................... 13
5.5 Terrain Maps as Project Baseline ...................................................................................................... 13
6.0 IMPORTANT ELEMENTS TO BE CONSIDERED IN DETAILED ENGINEERING TERRAIN
ANALYSIS (LEVEL 2D) ........................................................................................................................... 14
6.1 Determine Air Photo, LIDAR and Mapping Scale ........................................................................... 14
6.2 Determine the Map Base ................................................................................................................... 14
6.3 Refine Level 1D Mapping During Detailed Engineering Terrain Analysis (Level 2D) Mapping .... 15
6 4 D ib L l 2D T i M i C ti 15
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7.5 Terrain Classes in Map Legend ........................................................................................................ 18
7.6 Textural Modifiers for Mapping ....................................................................................................... 19
7.7 Landform Terms ............................................................................................................................... 20
7.8 Geomorphological Process Terms .................................................................................................... 20
7.9 Map On-Site Terrain Symbols .......................................................................................................... 21
7.10 Mapping Composite Terrain Units and Stratigraphic Terrain Units ............................................... 21
7.11 Typical Terrain Unit Titles for Terrain Stability Maps ................................................................... 22
7.12 Map Presentation ............................................................................................................................ 23
8.0 TERRAIN DATABASE FOR PRELIMINARY (LEVEL 1D) AND DETAILED (LEVEL 2D)
TERRAIN MAPPING ................................................................................................................................ 24
8.1 Pipeline Project Mapping (Level 1D and 2D) Database ................................................................... 24
8.2 BC Government Mapping Database for Submitting Mapping to Government ................................ 24
9.0 QUALITY CHECKING AND MAPPER QUALIFICATIONS .......................................................... 25
9.1 Quality Checking of Desktop PreliminaryTerrain Mapping (Level 1D) and Detailed Terrain
Mapping (Level 2D) ............................................................................................................................... 25
9.2 Terrain Mapper Qualifications In Canada Outside of BC................................................................. 25
9.3 Terrain Mapper Qualifications in BC ............................................................................................... 25
10.0 REFERENCES ................................................................................................................................... 27
APPENDIX A: LEGEND - TERRAIN CLASSIFICATION ALBERTA PIPELINE CORRIDOR (GSC
Terrain Classification System) .................................................................................................................... 28
APPENDIX B: PHYSIOGRAPHIC SUBDIVISION - ROCKY MOUNTAINS LEGEND (BC Terrain
Classification System) ................................................................................................................................ 31
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2. 0 SURFICIAL GEOLOGY MAPPING
2.1 Description of Surficial Geology Mapping
Surficial geology mapping forms the background for preliminary engineering terrain analysis (Level 1D).
It consists of preparing maps, cross sections, reports and tables of data that depict the extent, geometry
and properties of surficial materials. It also provides interpretative information concerning the geological
history and origin of the surficial materials. In Canada, this type of mapping has been carried out since
1842 by the Geological Survey of Canada (GSC) and more recently by provincial and territorial
geological and soil surveys. Most of Canada has been glaciated, so most near surface deposits have been
laid down since the last glaciation that began about 36,000 years ago and ended 10,000 years ago. These
deposits include glacial deposits (moraine, glaciofluvial, glaciolacustrine, and glaciomarine) and
nonglacial deposits (organic, alluvial, colluvial, lacustrine, marine and volcanic).
Mapping surficial geology on stereoscopic air photos made it possible to quickly trace map unit contacts
and to locate features without physically inspecting all map units and features them on the ground.
Reliance on air photos for identifying and tracing maps units reinforced the role of surface landforms in
defining map units (Fulton, 1993).
2.2 Example of Surficial Geology Mapping in Northern Canada
Surficial geology mapping in the Mackenzie Valley, Northwest Territories is an example of surficial
geology mapping carried out by the GSC from the 1960s to the present. Maps have been produced at
1:250 000 and 1:125,000 scale with summary maps at smaller scales. The mapping is based on
government stereo air photos produced at various scales ranging from 1:30 000 to 1:50 000. The surficial
geology maps have been field checked to confirm air photo interpretation.
Map legends for Mackenzie Valley map-sheets vary slightly between areas depending on slight deviations
in mapping conventions. The maps units are based on the stereo interpretation of landforms and their
characteristics including geological origin, texture, thickness, topography, drainage pattern and ground
ice. The GSC surficial geology mapping system allows the user to group terrain units into major terrain
classes of landforms with similar geological origin and surficial materials. Comments on the relationship
of terrain to engineering issues are also included in matrix style legends that often appear with the
surficial geology maps.
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3.0 ENGINEERING TERRAIN ANALYSIS
3.1 General Description of Engineering Terrain Analysis and Mapping
Engineering terrain analysis and mapping is related closely to surficial geology mapping discussed
previously. Engineering terrain analysis maps the distribution of certain types of surficial materials and
rock in specific landforms. It also identifies the geological processes that affect the terrain units and
assesses and rates the ability of various landforms and their materials to support different types of
activities during engineering construction and development.
3.2 Preliminary Engineering Terrain Analysis and Mapping (Level 1D)
Preliminary engineering terrain analysis and mapping (Level 1D) is developed from existing government
geological mapping, augmented by air photo interpretation where government mapping is not available.
Preparing the Level 1D map is used when analyzing the location of the pipeline corridor(s). This map also
highlights terrain issues along proposed pipeline corridor(s) before Level 2 D terrain mapping is carried
out on a chosen corridor. The Level 1D mapping provides preliminary information for construction cost
estimates before the more detailed Level 2D Engineering Terrain Analysis is completed.
Level 1D terrain analysis and mapping is carried out by transferring terrain unit boundaries from existingfederal or provincial government surficial geology maps to a map or maps with the pipeline corridor
superimposed. This information is entered into the project geomatics database. In areas where preliminary
surficialgeology mapping is missing government stereo photos are would be interpreted to fill in the
terrain mapping gaps. A list of typical terrain units along the pipeline route would be compiled by
kilometer post. Geological and engineering characteristics of terrain units along the right of way would be
collected in a matrix style legend by physiographic region. Terrain units would be grouped by geological
origin so that queries of major terrain groups can be carried out during preliminary engineering
assessment.
3.3 Detailed Engineering Terrain Analysis and Mapping (Level 2D)
The Level 2 D terrain analysis and mapping is carried out at a larger more detailed mapping scale (e.g.,
1:20 000 scale) when stereoscopic air photos have been flown along the selected pipeline corridor. The
Level 2D mapping both subdivides large polygons identified in the Level 1D mapping and incorporates
other project data (e.g., field observations from route reconnaissance and terrain mapping investigations,
boreholes logs or geophysics data) in the terrain unit descriptions. The first step in Level 2D engineering
terrain analysis is to map and describe the landforms and their characteristics on the air photos. Each
landform has a common geological origin, geomorphic expression, thickness and texture (grain size).
Landforms are then grouped on the basis of geological origin into major terrain groups.
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If the proposed pipeline project is located in more than one physiographic region, legends for each region
will be prepared because a terrain unit with a distinct geological origin can have different textural and
other properties in different physiographic regions. For example, the same map unit in the northern part ofthe Interior Plains of Canada may differ in material type and/or ground ice content from the same terrain
unit found in the southern Interior Plains.
A detailed engineering terrain mapping legend is usually shown in matrix style so that both geological
and geotechnical properties of terrain units can be viewed easily and queried in engineering analysis.
All information from the engineering terrain analysis (Level 2D) is entered into the project geomatics
database.
3.4 Example of Preliminary and Detailed Engineering Terrain Analysis (Level 1D and Level 2D)
from Northern Canada
Since the late 1970s engineering terrain analysis based on the GSC approach to landform and materials
mapping has been applied to northern pipelines proposed for the Mackenzie Valley (Polar Gas, 1975;
Beaufort Delta Oil pipeline, 1976; Foothills Pipelines, 1979 to 1982 both Yukon and B.C. Sections); Ikhil
Pipeline, 1996 and Mackenzie Gas Pipeline, 2003 to 2007).
The most recent engineering terrain mapping for the Mackenzie Gas Project followed the two stage
approach to engineering terrain analysis. The first stage of preliminary engineering terrain analysis (Level
1D) was carried out early in the pipeline project. It provided a generalized quick assessment of terrain
conditions along the pipeline corridor. It provided a conceptual assessment for the preliminary cost
estimate and determined areas where terrain conditions might require different routing. It was carried out
by transferring terrain unit boundaries from existing GSC surficial and bedrock geology maps to a base
map that followed the pipeline corridor. In areas where preliminary surficial geology mapping wasmissing, 1:50,000 and 1:60 000 scale government photos were interpreted to fill in the terrain mapping
gaps. A list of typical terrain units along the route was compiled by kilometer post and engineering
considerations related to the terrain units along the right of way were collected in a matrix style legend.
Legends were prepared for each of the physiographic regions. Terrain units were grouped by geological
origin so that queries of major terrain groups or other right of way considerations could be carried out
during engineering assessment.
The second level terrain analysis known as Level 2D terrain mapping was carried out on the Mackenzie
Gas Project right of way from 2004 to 2006 after the route was finalized. It was based on larger scale 1:20
000 stereo air photos that were flown for the pipeline project. In this more detailed mapping large
polygons identified in the 1D mapping were subdivided into more categories based on the mapping scale
and the incorporation of borehole data and field investigation information in terrain unit descriptions. For
example, the thickness of organic terrain units could be distinguished more easily using the more detailed
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Terrain units were grouped by geological origin so that queries of major terrain groups or other right of
way considerations such as geohazards could be carried out during engineering assessment. It should be
noted that the more detailed (level 2D) engineering terrain analysis should systematically record thicknessinformation for stratigraphic units. For example, a terrain unit indicated as a veneer is 3 m
thick.
3.5 Example of Preliminary and Detailed Engineering Terrain Analysis (Level 1D and 2D) for
Pipeline Projects in Alberta and BC
Terrain analysis has also been carried along pipeline corridors in Alberta and BC. The methodology was
the same as that used in the two stage Mackenzie Valley pipeline corridor mapping where both Level 1D
and 2D engineering terrain analysis was carried out. GSC, Alberta Geological Survey (AGS) or British
Columbia government surficial geology mapping was used for preliminary Level 1D work.
Level 2D mapping has been carried out at several locations in northern and central Alberta by consultants
to TransCanada. Project air photos at 1:20 000 scale and LIDAR were used for the detailed Level 2D
mapping. Boreholes and/or geophysics, when available, added information to describe terrain polygonsand stratigraphic conditions in the detailed terrain analysis. This Level 2D terrain analysis work in Alberta
usually has terrain unit titles similar to those used in northern Canada mapping because the GSC and AGS
regional surficial geology mapping systems used in the Level 1D mapping are fairly similar( for legend
see Appendix A).
It should be noted that the BC terrain classification and stability mapping system developed for the forest
industry in BC differs to some extent from GSC and AGS surficial geology mapping. This system was
developed originally to aid the forestry industry for mapping terrain and terrain stability in mountainous
areas. Terrain stability ratings based on slope class and material type were applied to individual polygons
and related to the development of cut blocks and roads in these polygons. The BC system has codified
and published explanations of every aspect of terrain mapping. This detail was required because the
terrain stability mapping system was written into legislation governing forest practices and has methods
and standards that can be included as legally binding contracts with terrain mappers (Ryder and Howes,
1984; Howes and Kenk, 1988 and 1997).
The BC mapping system emphasizes terrain stability ratings in mountainous terrain and does not have
certain details regarding terrain unit thickness and stratigraphy that applies to pipeline planning andconstruction. It does not always present a matrix style legend that can be applied to engineering queries.
Recently the BC system has been applied to terrain mapping for some Alberta pipeline projects.
In BC the BC terrain classification and terrain stability mapping system has been used (with some
modification to terrain unit thickness data and legend structure and presentation) for engineering terrain
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and bioterrain maps) have complicated descriptions of percentages of types of material of different
geological origin in each polygon. This does not help the user in pipeline project planning determine the
primary character of each mapped polygon. Also terrain unit thickness descriptions in the B.C. terrainmapping system are not as systematic as they should be for buried pipelines. In pipeline work the
stratigraphy and thickness of terrain units is important to the characterization of the ditch. Therefore,
Level 2D maps should consider that terrain analysis and mapping for pipeline projects will need some
additional information not always evident in the B.C. mapping system.
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4.0 SELECTION ENGINEERING TERRAIN MAPPING SYSTEM FOR A PIPELINE
PROJECT
4.1 Existing Government Surficial Geology Mapping System
The terrain mapping system chosen for the Level 1D and Level 2D work should have similar terminology
to the existing federal or provincial government bedrock and surficial geology maps available for the area
in which the pipeline is located.
If ecosystem or bioterrain maps are the only available maps with geological descriptions they can also
contribute to preparing the Level 1D terrain maps and engineering takeoffs. However, these maps should
be assessed to make sure that the map units have information on landforms, soil material, and topography(B.C. Resources Inventory Committee, 1995).
4.2 Consider the Terrain Issues Relevant to the Area of Study
The terrain mapping system should assess the surficial and bedrock geology in the area that is crossed by
the pipeline. Any terrain mapping system chosen should consider mapping landforms and describing soil
and bedrock in the landforms including textures of soil materials, bedrock type, thickness of terrain units
and slope class information from DEM and/or LIDAR. Other terrain unit properties, geologic processes
and geohazards should also be shown.
In mountainous terrain slope class and terrain stability assessment should be included in the terrain
mapping system.
In permafrost terrain soil information should be assessed relative to frozen and unfrozen ground. Organic
thickness is critical and should be assessed carefully in northern areas with permafrost and non-
permafrost terrain.
4.3 Consider the Terrain Mapping Experience of the Government Reviewers of the Pipeline Project
If surficial geology maps are available along the pipeline corridor, government reviewers may be familiar
with the mapping system shown on these maps. Introduction of a new mapping system for the Level 1D
and 2D engineering terrain analysis that was developed in an area with different geology, soils and
topography may confuse reviewers who may not be familiar with a mapping system taken from another
area or mapping system.
Always consider the reason that the government geological mapping was produced (e.g., regional bedrockor surficial geology mapping or forestry or bioterrain work) and adapt what is relevant to Level 1 and 2 D
pipeline engineering terrain analysis and mapping.
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5 0 ENGINEERING TERRAIN ANALYSIS AND ITS CONTRIBUTION TO
DETERMINING KEY ITEMS FOR PIPELINE PLANNING, CONSTRUCTION AND
OPERATION5.1 Pipeline Right of Way Continuous Terrain Information for Engineering
Engineering Terrain Analysis (Level 1D and Level 2D) are used to provide a continuous record of terrain
units and their landform characteristics along a pipeline corridor The mapped terrain units and their
properties, presented in a matrix style legend, are queried using algorithms and these queries are used to
delineate issues related to pipeline planning, design and construction. This analysis also adds to
information needed to compile costs for construction and mitigation measures.
The properties of terrain units include information on the soil or bedrock type in each terrain unit, the
landform characteristics of the terrain unit including thickness of surficial soil material, topography of the
landform, slope classification, surface drainage information, active geological processes and geohazards
associated with each terrain unit. Comments about terrain units related to their natural state and their
reaction to disturbance during construction are also recorded in the matrix style legend and can also be
queried.
Engineering right of way issues including thaw settlement, erodability, roughness of the land surface,boulder content in terrain units, buoyancy and soil pipe interaction depend on the continuous take off of
pipeline terrain units and their characteristics. The terrain mapping may be used to locate boreholes along
the pipeline right of way. These boreholes may be necessary to confirm soil properties and stratigraphy.
5.2 Pipeline Right of Way Ditch Properties
Level 1D and Level 2D terrain unit information can also provide information that is important indescribing properties of the right of way ditch including:
the type and properties of overburden
overburden thickness (depth to bedrock)
bedrock type
Knowledge of these items taken from the Level 1D and Level 2D engineering terrain analysis and
mapping are used to determine ditchability and to calculate buoyancy, ditch settlement and/or frost heave.Bedding and padding requirements are also calculated from the right of way ditch properties.
5.3 Level 1D and Level 2DTerrain Mapping Describes Land at Pipeline Infrastructure Sites
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5.4 Location of Geohazards
The Level 1D and Level 2D engineering terrain analysis and mapping describes geohazards in varioustypes of terrain. The terrain mapping may show the geohazard as a terrain polygon or a map symbol. The
identified geohazards can affect pipeline routing, construction and operation (Rizkalla et al., 2008).
Geohazards may include:
landslides/mass movements (deep seated landslides, soil creek, thawed layer detachment slides,
rockfalls, snow or rock avalanches, debris flows)
tectonic events (recent faulting, earthquakes, liquefaction)
geochemical events (karst in gypsum or limestone, saline soil and groundwater, ML/ARD in
bedrock) hydrologic events (river channel migration, buoyancy or pipe uplift, rapid lake drainage, coastal
inundation and flooding)
volcanic events (ash falls, lahars, pyroclastic flows)
desert events (dune migration and flash flooding in wadis)
thermal events related to the freezing of unfrozen ground (frost heave of the pipe or ditch, frost
bulb development cross country and at river crossings, frost blisters and ice-wedge cracking)
thermal events related to thawing of permafrost (thaw settlement of pipe, ditch and right of way),
thawing of frost bulb on slopes, and thawing of massive ice (thermokarsting)
5.5 Terrain Maps as Project Baseline
Terrain maps provide baseline information that can be used on project alignment sheets or in a
geotechnical atlas that may accompany the project application. The terrain map can be upgraded and
revised during the life of the pipeline project as subsurface information is collected during various phases
of the project. Upgraded terrain map information can be used for later phase cost estimates and for
preparing for post construction operation of the pipeline.
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6.0 IMPORTANT ELEMENTS TO BE CONSIDERED IN DETAILED ENGINEERING
TERRAIN ANALYSIS (LEVEL 2D)
6.1 Determine Air Photo, LIDAR and Mapping Scale
The scale for air photo, LIDAR and mapping scale should be determined early in the project. The air
photo, LIDAR and terrain map scales should be chosen to meet regulatory requirements and to show
enough detail for the Level 2D terrain analysis. The scale choice should not be so detailed that terrain
mappers cannot meet the schedule required for office and field investigations. The air photos and terrain
mapping should be close to or at the same scale. Overlap on stereoscopic air photos should be at 60%,
similar to government of Canada stereo air photos.The map polygon size will be determined by the
mapping scale and also by the characteristics of terrain in different topographic settings. There will be
larger polygons in flat to rolling terrain than in mountainous terrain.
Level 2D mapping should cover the project footprint. The project footprint should be a minimum of 2 km
wide and centered on the pipeline This footprint should include the right of way and should be wide
enough to encompass geohazard areas (e.g. to top of ridges in mountainous terrain), wider areas at river
crossings to cover possible crossing relocations, and include potential off right of way locations (e.g.
camps or important access roads).
Engineering terrain analysis and mapping at a scale of 1:20 000 has been used for many long distance
pipeline projects in Canada. This mapping scale provides enough detail to map terrain for continuous
engineering take off work and can be completed in a reasonable time period for project use.
If the mapping is being done in BC., Level D terrain stability mapping should be part of the terrain
mapping output on the 1:20 000 scale air photos. In Level D terrain stability mapping, the Terrain Survey
Intensity Level (TSIL) requires that 1 to 20% of the polygons would be ground checked by vehicle and
flying with limited ground observations. Other detailed mapping at an even larger scale (e.g. 1:7 500)
may be carried out at a later date in unstable areas where necessary (Ryder, 2002).
The continuous terrain map of the pipeline corridor is the baseline information for engineering queries on
the right of way and for terrain descriptions off right of way.
6.2 Determine the Map Base
Terrain mapping should be compiled on an air photo map base prepared from the project air photos or ontopographic maps at a scale of 1:20 000 (e.g., B.C. Government topographic TRIM maps). It should be
noted that project air photos and topographic map bases do not always match, particularly where air
photos are more recent than the maps. If this is the case, it is probably better to use the air photos to make
the base map. It should be noted that pipeline alignment sheets and geotechnical atlas sheets are mostly
developed from project air photos. If air photos are used, a geomatic determination of slopes using
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6.3 Refine Level 1D Mapping During Detailed Engineering Terrain Analysis (Level 2D) Mapping
It is important to use the Level 1D terrain mapping in early stages of project work and to upgrade themapping during Level 2Ds mapping activities. The Level 2D mapping will show more detail because of
the larger scale of the project air photos. Larger polygons from the Level 1D mapping will be subdivided
and more terrain features will be mapped on the larger scale air photos. If the Level 1D mapping was
done for other purposes than surficial geology mapping (e.g. bioterrain mapping or ecosystem mapping)
terrain and landform information will be refined in the Level 2D mapping.
6.4 Describe Level 2D Terrain Mapping Conventions
Terrain units should be compiled into genetic terrain groups. These groups are then organized from the
geologically youngest to oldest in the terrain legend that is prepared for each physiographic region.. The
genetic categories should be relevant to the geology of the area being mapped. For example, the major
terrain groups in glaciated and non-glaciated terrain in Canada are from youngest to oldest: Organic,
Colluvial, Lacustrine, Marine, Eolian, Fluvial (Alluvial), Glaciolacustrine, Glaciofluvial, Moraine, and
Bedrock. The terrain units (including information on their properties) in each of the genetic categories
may vary between physiographic regions. For this reason, a matrix style legend should be prepared foreach physiographic region so that specific categories of information can be compiled and queried.
The individual terrain units fall within the major terrain groups. Each terrain unit is listed in the legend by
terrain group. Thickness, textural information, topography, soil drainage, slope class and any mass
wasting features identified in the polygon are important for each terrain unit described in the matrix style
legend. In some cases it may be necessary to map more than one landform in a polygon. However, this
should not be done in every map polygon because it is important to know the primary landform and its
properties for pipeline engineering analysis. If two or more titles are used in a polygon percentagebreakdowns should be shown in the polygon title. Landforms and landform morphology terms should be
explained in the map legend. Each terrain polygon should have a unique number for use in preparing the
final map product.
The textural modifiers may vary in different mapping systems. Their letter symbols usually precede the
capital landform symbol. The order of textural modifiers used should be in agreement with the mapping
system being used and the order of the letter symbols should be described in the legend. The order of the
textural symbols differs between the B.C. and GSC and AGS mapping systems. The legend should define
the order of importance of the textural properties.
Geomorphological process terms following a dash (-) after the terrain unit symbol. These process terms
and any drainage terms used in the map polygons should be described in the map legend. Terrain features
that are shown with symbols on the map should also be identified in the legend. Any slope class
breakdowns and ranges of slopes in percent and degrees should also be listed in the map legend If a
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7.0 B.C. TERRAIN CLASSIFICATION AND MAPPING AND TERRAIN STABILITY
MAPPING APPLIED TO DETAILED ENGINEERING TERRAIN ANALYSIS (LEVEL
2D) FOR PROPOSED BC PIPELINESThis section of the report describes how to apply the BC Terrain Classification and Mapping and Terrain
Stability Mapping Systems to proposed pipeline corridors in BC. The details of these mapping systems
are described in BC government publications listed in References (Forest Practices Code of BC, 1995 and
1999; Howes and Kenk, 1988 and 1997; Resource Inventory Committee 1996a and 1996b; Ryder and
Howes, 1984 and Ryder and Associates, 2002). The BC terrain classification and mapping system and
terrain stability mapping system were developed for the forestry industry and differ in some respects
from the terrain mapping systems used in other parts of northern and western Canada. Certain types of
information relevant to pipelines need to be added when applying this type of mapping to pipelines.
7.1 Determine Map Boundary Lines.
In B.C. terrain mapping and terrain stability mapping, three types of boundary lines are used (page 30 of
Ryder 2002 publication). These line types were used to represent well-defined (solid line), approximate
(dashed line) and assumed (dotted line) boundaries. In order to carry out digital mapping and map
takeoffs and database enquiries for pipeline engineering quantities solid lines should be used for all
boundaries in pipeline terrain mapping using the BC terrain mapping system.
7.2 Designate the Terrain Unit
Terrain maps subdivide the land surface viewed on stereo air photos into a series of polygons or terrain
map units. The map unit is the main descriptive subdivision of the map. It attempts to subdivide themapped area into the purest units consistent with the mapping scale. Each terrain map unit is identified
primarily on the basis of its geological origin, landform and texture. The geologic origin is represented by
the upper case letter in the middle of the terrain unit symbol. The texture of the material in the terrain unit
is represented by the lower case letters before the upper case letter and the surface expression is
represented by the letters that follow the upper case geological origin symbol. For example, sg FGt is a
sand and gravel (sg) glaciofluvial terrace (FGt) according to the terminology of the B.C. terrain mapping
system. Geological processes (active and past) that affect terrain units are also recorded during the
mapping process. For example the sgFGt mentioned above may have been affected by a geologicalprocess. A symbol sgFGt-H indicates a glaciofluvial terrace that is kettled (-H) was affected by a past
geological process that is currently inactive. Geological features that are too small to map as polygons are
noted as symbols during the mapping process. Other geological characteristics (topography, slope class,
drainage, and permafrost) are also described during the mapping process and can be shown in the terrain
unit title and/or in the matrix style terrain legend
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properties (e.g. a boulder moraine plain from one type of glaciation btMp(1) versus moraine plain with a
gravel sized coarse fraction gMp(2) from a second type of glaciation. Even though till (t) also recorded as
a combination of textures (dscz) is assumed and not recorded in the title of M terrain units in B.C. terrainstability mapping, pipeline work always needs to distinguish (t) or (dscz) as a texture preceding the M in
the terrain unit title. This texture is useful in engineering queries for ditchability and in planning for
subsurface field assessments.. The matrix legend that describes the M terrain unit may also show that
different types of till are found in different physiographic regions.
7.3 Prepare the Map Legend
A map legend classifies and describes terrain units that have been shown on the map. The objective of the
legend is to provide information on the characteristics of the terrain units in an organized way. A matrix
style legend should be used to show this information and to simplify database queries on terrain unit
engineering properties. The compliment of terrain units in the matrix terrain legend may differ between
physiographic regions and subdivisions along the pipeline corridor (Holland, 1976). For example, till in
the Rocky Mountains may differ texturally from till in the Coast Mountains. Separate legends should be
made for each physiographic division. Elements that should be included in each physiographic division
matrix style legend are as follows:
1. Primary Legend Elements
The map unit symbol including genetic, geomorphologic textural information (e.g. gFf)
The landform represented by the terrain unit including a written description (e.g. Fluvial Fan)
Landform characteristics [morphology, topography, texture, rock type (if known), permafrostand ice content, drainage, groundwater (if known), thickness of terrain unit (relative to
pipeline thickness categories), average slope class (Howes and Kenk, 1997, p.27), active
geological processes, permafrost and ice content information (if present) comments on terrain
units relative to construction, and terrain stability rating]
Note: The texture of soil material in the terrain unit (order of texture terms has most
important texture next to terrain unit title (e.g., btMp)
2. Separate Legend Information Including Tables and Symbols
Table showing genetic categories and Terrain Class Letter
Table describing textural terms for surficial materials
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List of symbols showing features that are too small to map as polygons (e.g. gullies,
escarpments and geohazard features)
Symbols showing the locations for field investigations (e.g. surface observation sites,borehole locations and geophysics lines)
Description and example of qualifying legend descriptors
Table explaining stability classes for terrain units (Forest Practices Code, 1995)
An example of a typical BC terrain legend is given in Appendix B
7.5 Terrain Classes in Map Legend
Individual terrain units are grouped into terrain classes (youngest to oldest) based on their genetic origin.
Grouping terrain units into terrain classes helps in compiling summary properties for engineering
database queries. The summary terrain class labels (letters) in the B.C. Terrain Classification are shown in
Table 1. If colors are used in map presentation, it is proposed that they should follow the standard colors
used in federal mapping. Water should be shown in a different blue than marine and glaciomarine.Geomatics database work and computer mapping have difficulties in registering superscript titles (e.g.FG,
LG) so column two in Table 1 shows an alternate scripting that can be used in database and mapping
work.
TABLE 1:GENETIC CATEGORYTERRAIN CLASS B.C.TERRAIN MAPPING SYSTEMTerrain Class Label
(Letter)
Terrain Class (Label)
Letter for Database &Geomatics Work
Class Name Color on Map****
A Anthropogenic -
O Organic Grey
I Ice -White
F Fluvial Yellow
C Colluvial Brown
E Eolian Yellow Grey
L, Lacustrine Light Purple
W Marine Light BlueLG LG Glaciolacustrine Purple
WG WG Glaciomarine Blue
FG FG Glaciofluvial Orange
M Moraine(Till) Green
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7.6 Textural Modifiers for Mapping
Textural modifiers are symbolized on terrain maps as small letters before the letter signifying the geneticclass. These are attached to terrain unit titles and confirmed by field investigations (field mapping and
boreholes). If no field work is carried out in the polygon, the texture is only an estimate from the
knowledge base of the mapper. However, these textures are important to estimate during the desktop
mapping exercise because field confirmation often occurs sometime after the preliminary terrain mapping
is completed and the 1D terrain take offs are carried out. The textural titles can be changed as a result of
field investigations.. Common textural modifiers shown as small letters before the letter signifying the
genetic class are shown in Table 2.
There are conventions for indicating textural terms when more than one texture is shown in a terrain unit
designator (p. 7 & 8, Howes and Kenk, 1997). Usually not more than three textural terms should be used
and they are listed in reverse order of importance so that the terrain unit designator may be easily
verbalized. For example b,gFt indicates that the common texture is gravel (g) but the gravel has some
boulders (b). Bedrock terms, like terrain textures, are shown before the genetic term in the terrain unit
title. For example, a limestone polygon (ls) could be mapped as lsRs where limestone on steep slopes is
involved. The order of rock types is similar to the order of soil textures with the most common rock type
next to the R symbol.
TABLE 2:TEXTURAL MODIFIERS (FROM B.C.TERRAIN MAPPING SYSTEM;HOWES AND KENK,1997)
Letter Texture Brief Description
a * Blocks Angular Particles > 256 mm in size
b * Boulders Rounded Particles > 256 mm in size
k Cobbles Rounded particles between 64 and 256 mm in size
p Pebbles Rounded particles between 2 and 64 mm in sizes * Sand Particles between .0625 and 2 mm in size
z* Silt Particles between 2m and .0625mm in size
c* Clay Particles < 2m in size
d Mixed Fragments A mixture of rounded and angular fragments greater than 2 mm in size
x Angular Fragments A mixture of angular fragments greater than 2 mm ins size; (i.e. mixture of blocksand rubble)
g * Gravel A mixture of two or more size ranges of rounded particles greater than 2 mm in
size (e.g. a mixture of boulders, cobbles and pebbles); may have interstitial sandr * Rubble Angular particles between 2 and 256 mm; may include interstitial sand. Usually
no fine material
m Mud A mixture of silt and clay; may also contain a minor fraction of fine sand
y Shells A sediment consisting dominantly of shells and/or shell fragments
e Fibric - Organic Least decomposedorganics- Well preserved fibre (40%or more) identifiedas
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7.7 Landform Terms
Landform morphology (also known as surface expression) terms are indicated after the genetic terrain
class letters in the terrain unit designator. The Terrain Classification System for British Columbia p. 26
gives a list of the key to landform terms that are summarized in Table 3 below (Howes and Kenk, 1997).
TABLE 3: LANDFORM MORPHOLOGY TERMS IN B.C.TERRAIN CLASSIFICATION SYSTEMLandform Morphology or SurfaceExpression Name
Letter Symbol in Terrain Unit Designator
moderate slope (apron) a
blanket b
cone(s) cdepression(s) d
fan(s) f
hummock(s) h
gentle slope j
Moderately steep slope k
rolling m
plain p
ridge(s) r
steep slope sterrace(s) t
undulating u
veneer v
mantle of variable thickness w (Dont use for Pipeline Terrain Work)
thin veneer X (Dont use for Pipeline Terrain Work)
The B.C. Terrain Classification System publication (Howes and Kenk, 1997, p. 27) describes the method
of selecting surface expression terms. It should be noted that the thickness determination of a blanket anda veneer should be modified to assist pipeline engineering take-offs. Engineering terrain analysis for
pipelines is cognizant of the pipeline location within the ditch. With this requirement considered, the
veneer would include veneer and thin veneer and would be 3
m thick.
7.8 Geomorphological Process Terms
Geomorphological process terms follow the landform or surface expression term in the terrain unit
designator. For example zLGt-V is a silty glaciolacustrine terrace that is gullied by active
geomorphological processes. The B.C. Terrain Classification System has a description and list of the
geomorphological process terms in Chapter 4 Table 4 below is compiled from that publication (Howes
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TABLE 4:GEOMORPHOLOGICAL PROCESS TERMS FOR B.C.TERRAIN CLASSIFICATIONSYSTEM
Group Process Name Map Symbol Assumed Status of Process
Erosional Processes DeflationKarstPipingGullyingWashing
DKPVW
ActiveActiveActiveActiveActive
Fluvial Processes Braiding ChannelIrregular Channel (sinuous)
Anastomosing ChannelMeandering Channel
BIJM
ActiveActiveActiveActive
Mass MovementProcesses
Snow AvalanchesSlow Mass MovementsRapid Mass Movements
AFR
ActiveActiveActive
Periglacial Processes CryoturbationNivationSolifluctionPeriglacial Processes (General)Permafrost Processes
CNSZX
ActiveActiveActiveActiveActive
Deglacial Processes Channelled
Kettled
C
H
Inactive
InactiveHydrologic Processes Inundated
Surface SeepageUL
ActiveActive
Geomorphological SubClass Terms are listed in Chapter 7 of the B.C. Terrain Classification System
Publication (Howes and Kenk, pages 66 to 73, 1997) and will not be repeated here. These subclasses
relate to Mass Movement Processes, Fluvial Processes, Permafrost Processes and Bedrock Subclasses.
These terms should be used in polygon titles where relevant. Tables describing the terms used should
show as part of the terrain map legend. It appears that the most used subclass terms in the terrain stability
mapping process will come from Table 6.1 Subclasses for Mass Movement. Bedrock Subclasses should
conform whenever possible to the rock types in either column 2 or 3 of Tables 6.4 to 6.6 (Howes and
Kenk, p. 71 to 72, 1997). Major bedrock types can be determined from the existing GSC and B.C.
government bedrock maps. The rock types in column 3 are the most detailed and used if possible. Mixing
of the rock types from columns 2 and 3 should be avoided.
7.9 Map On-Site Terrain Symbols
Terrain symbols are graphic representations used to describe landforms, features or processes. These
symbols represent features that are too small to map as polygons, indicate a location in a landform for a
feature or process, or indicate a landform or feature that cant be shown by a terrain unit designator. A list
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polygon. Composite terrain units have been shown in various ways by delimiters (Howes and Kenk, page
63, 1997) or deciles (Howes and Kenk, page 64 and 90, 1997).
For clarity in engineering take offs, deciles should be used to describe composite units (e.g., 6tMv4Cv or6tMv4Cv in database script). It should be noted that it is difficult to make engineering queries if too many
composite polygons are outlined during the mapping process. Distinct single unit polygons are preferred
whenever possible.
Stratigraphic terrain units are shown when one type of material overlies another type of material. This
type of unit is particularly important for pipeline work. Materials are shown in stratigraphic order
separated by a line. For example,
(also shown as sLv/gFGp or sLv\gFGpfor mapping and database
work) represents less than 1 m of lacustrine sand overlying gravelly glaciofluvial plain deposits that aregreater than 3 metres thick.
Before accepting a mapping convention for a composite or stratigraphic terrain unit, the terrain mapping
database must be set up and structured to accommodate composite and stratigraphic terrain units so that
deconstructing the various symbol elements into component parts for each terrain unit will permit
engineering queries to be conducted. If the title is more complicated it will need to have other title
elements also deconstructed in the original terrain mapping database (e.g. geomorphological process
terms and composite terrain unit titles). An example of the original terrain database structure should be
supplied early in the mapping process along with the preliminary map examples to see if it can be used
for engineering queries.
7.11 Typical Terrain Unit Titles for Terrain Stability Maps
The terrain unit title shown on a terrain stability map should have the following information:
polygon number
terrain unit title including grain size preceding the terrain unit
major slope class in the polygon in % and degrees (Classes 1 to 5)(according to Howes and Kenk,
p.27, 1997. These classes are as follows:
Class % Degrees
1 0 5 0 3
2 6 -26 4 15
3 27 49 16 26
4 50 70 27 35
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units, slope classes and stability consideration in the five stability classes for each of the
physiographic subdivisions.
For example, the title on a polygon for a terrain stability map might be as follows:
Example Symbol: 105 ..Polygon Number
tMb (Slope Class 2; tMb is Terrain Symbol)
2 lsR lsR
w Drainage
II Stability Class (Stable)
7.12 Map Presentation
Terrain stability mapping will be shown on a series of 1:20 000 scale base maps along the pipeline
corridor with a relevant physiographic subdivision detailed legend attached to maps in each physiographic
subdivision. Only one terrain stability map, not a series of maps, will be prepared for any specific area
along the pipeline corridor.
Detailed legends will be prepared for each of the major physiographic subdivisions as described in
Sections 7.3 to 7.8 of this report. The legend describing the terrain units and terrain classes will be matrix
style (Section 2.3 and Appendix B). The rest of the legend will consist of attached tables describing
terrain classes, textural terms, landform morphology terms, geomorphological process terms, mass
movement processes, qualifying descriptors, and a table describing slope stability interpretations. A list of
symbols will be part of the legend as will be a description of the slope classes in percent and degrees (see
Section 7.11 of this report).
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8.0 TERRAIN DATABASE FOR PRELIMINARY (LEVEL 1D) AND DETAILED
(LEVEL 2D) TERRAIN MAPPING
8.1 Pipeline Project Mapping (Level 1D and 2D) Database
The terrain mapping database structure should be set up to capture mapping information in column format
and use algorithms to construct terrain mapping codes for use on maps. It must be able to construct and
deconstruct symbology and will need to be shared with geomatics specialists assigned to specific pipeline
projects. . It is essential that all elements of the terrain mapping are stored in queriable fields and formats
for the purposes of generating associated engineering takeoffs.
8.2 BC Government Mapping Database for Submitting Mapping to Government
The Terrestrial Ecosystem Information Digital Data Submission Standard Draft for Field Testing,
Database and GIS sets our procedures and rules for submitting Terrestrial standards(RISC, 2012) sets
out procedures and rules for submitting Terrestrial Ecosystem Information (TEI) data to the B.C. Ministry
of Environments Terrestrial Ecosystem Information System (TEIS) and other database systems. The
ministry has developed Contractor Package (Version 10, Dec 19, 2012) containing information for
contractors to meet the goals of acquiring and administering terrain related data in an organized fashionthroughout the province to meet the objectives of the Resources Information Standards Committee
(RISC). This draft document consolidates all of the submission standards for terrestrial ecosystem
mapping (TEM), bioterrain mapping and terrain stability mapping (TSM) into a single framework for
digital data submission. The new standard reflects the change from the B.C. Ministry of Environmentrequired data submission in .E00 format to .gdb format.
The database schema associated with this standard (TEI_Long_Tbl Feature Class Data Description) is
found in Appendix A of the standard. The database stores individual attributes in a normalized manner
that facilitates data queries and construction of map symbols. Additional descriptions of attribute fields,metadata, allowable codes and domain tables in the geodatabase are included in the other appendices. The
database structure can be modified with additional fields and with additional allowable codes in given
fields as required for each specific project. Any terrain mapping contractor should review the database
schema to ensure consistency with these specifications when submitting mapping to the government.
In order to construct terrain polygon labels to display on maps, the B.C. Ministry of Environment uses a
script to create a concatenated label derived from the TEI_Long_Tbl (parsed 280 fields). The long table
schema has all the data parsed out so a user can create a concatenated terrain label.On site symbols arealso included in the B.C. Ministry of Environments Operation Geodatabase. Any terrain mapping project
should provide feature coded feature classes for on-site symbols.
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9.0 QUALITY CHECKING AND MAPPER QUALIFICATIONS
9.1 Quality Checking of Desktop PreliminaryTerrain Mapping (Level 1D) and Detailed Terrain
Mapping (Level 2D)
Preliminary (Level 1D) mapping and detailed (Level 2D) will need to have quality assurance checking by
the user (engineering in the case of pipeline terrain mapping) to make sure that the mapping meets the
users needs. Each mapper, if more than one is doing the work, should undertake a small section of
mapping (e.g. 25 km) so that mapping styles can be coordinated.
Further checking should be done using LIDAR, where available, as it sometimes refines polygon
boundaries.
Preliminary legends should be prepared before field investigations. Both terrain mapping and legends can
be upgraded after field investigations are completed.
Field notes should be kept in an organized way so that they can be used to finalize the Level 2D terrain
maps.
9.2 Terrain Mapper Qualifications In Canada Outside of BC
Terrain mapping outside of BC is not regulated to the same extent as it is in BC. However, terrain
mappers in Canada are generally geologists with knowledge of geological mapping and the principles of
air photo interpretation and engineering terrain analysis. Occasionally terrain mapping is undertaken by
foresters, soil scientists or engineers but these individuals need to have some of the same background as
geologists in both desktop and field studies. It is preferable that mappers are registered as a professional
geoscientist, professional engineer, or professional agrologist in the area where they are working. All
mappers should understand the government geological mapping that is used for Level 1D mapping alongthe pipeline corridor that they are mapping.
9.3 Terrain Mapper Qualifications in BC
BC requires that a registered professional heads up terrain mapping and terrain stability mapping (Forest
Practices Code, 1995).. This individual should have substantial experience in terrain mapping and
landslide hazard interpretation. Junior mappers can do this work under close, professional supervision..
Professionals that currently carry our terrain or terrain stability mapping include:
Professional geoscientists (P.Geo) are primarily geologists and geomorphologists who have
terrain and terrain stability mapping experience and are registered with the Association of
Professional Engineers and Geoscientists of BC (APEGBC)
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Resumes of all mappers should be attached to terrain mapping proposals submitted for terrain and terrain
stability mapping of pipeline corridors.
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10.0 REFERENCES
Forest Practices Code of British Columbia. 1995. Mapping and Assessing Terrain Stability Guidebook.
B.C. Ministry of Forests and B.C. Environment.
Forest Practices Code of British Columbia. 1999. Mapping and Assessing Terrain Stability Guidebook.
B.C. Ministry of Forests and B.C. Environment
Ecosystems Working Group of the Terrestrial Ecosystems Task Force Resources Inventory Group. 1995.
Standards for Terrestrial Ecosystems Mapping in B.C. The Province of British Columbia, Resources
Inventory Committee, 190p.
Fulton, R.J. 1993. Surficial Geology Mapping at the Geological Survey of Canada: Its Evolution to meet
Canadas Changing Needs. Canadian Journal of Earth Sciences, Volume 30, Number 2.
Holland, S.S. 1964 (Revised 1976). Landforms of British Columbia: A Physiographic Outline. British
Columbia Department of Mines and Petroleum Resources, Bulletin No. 48.
Howes, D.E. and Kenk, E. editors. 1988. Terrain Classification System for British Columbia Revised Ed.
Ministry of Environment Recreational Fisheries Branch and Ministry of Crown Lands, Surveys and
Resource Mapping Branch, MOE Manual 10.
Howes, D.E. and Kenk, E. 1997. Terrain Classification System for British Columbia (Version 2) FisheriesBranch, Ministry of Environment and Surveys and Resource Mapping Branch, Ministry of Crown Lands,
province of British Columbia, MOE Manual 10 (Version 2).
Resource Inventory Committee. 1996a. Interim (1996) Terrain Database Manual: Standards for Digital
Terrain Data Capture in British Columbia.
Resource Inventory Committee. 1996b. Specifications and Guidelines for Terrain Mapping in British
Columbia, Surficial Geology Task Force, British Columbia.
RISC. 2012. Terrestrial Ecosystem Information Digital Data Submission Standard Draft for Field
Testing, Database and GIS Data Standards. Prepared by Ministry of Environment Knowledge
Management Branch for the Terrestrial Ecosystem Resources Information Standards Committee, March
20, 2012, Version 2.1.
Rizkalla, M. (editor). 2008. Pipeline Geo-Environmental Design and Geohazard Management. Pipeline
engineering Monograph Series, ASME, Three Park Avenue, New York, 353p.
Ryder J.M. and Howes, D.E. 1984. Terrain Information, a Users Guide to Terrain Maps in BritishColumbia in DEGIFS Publication.
Ryder, J.M. and Associates. 2002. A Users Guide to Terrain Stability Mapping in British Columbia,
British Columbia Surveys and Resource Mapping Branch, Victoria.
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SLOPE INFORMATION
SLOPE CLASS PERCENT DEGREES
1 0 - 0.5 0
2 0.5 - 2 0.3 - 1
3 2 - 5 1 - 34 6 - 9 3.5 - 5
5 10 - 15 6 - 8.5
6 16 - 30 9 - 177 31 - 45 17 - 24
8 46 - 70 25 - 359 71 - 99 36 - 4510 100 45
POLYGON INTERPRETATION
Fen Organic Veneer overlying Moraine Plain = fOv/tMp
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APPENDIX B: PHYSIOGRAPHIC SUBDIVISION - ROCKY MOUNTAINS LEGEND (BC Terrain Classification System)
MapSymbol TerrainUnit Texture Thickness Topo-graphy Soil Drainage Permafrost SlopeClass(es)
(After
Howes &
Kenk, 1997)
Mass WastingFeatures Comments StabilityRating (After
Forest
Practice Code)
Ov Organic
Veneer
Peat and Fen 3m Level Poorly Drained Possible inorganics
1 None PoorTrafficability
I = Stable
Cv ColluvalVeneer
Matrix is SiltySand or sandysilt; Also hasrock fragments(rubble)
< 1m Gently toSteeplysloping
Well Drainedover rock;Moderately wellto imperfectlydrained overfine grainedmaterial
None 2 to 5 Gullies andDebris TorrentGullies
II toV= Stableto Unstable
Cb Colluvial
Blanket
Sand or sandy
silt; Also hasrock fragments(rubble)
1 to 3m Gently to
SteeplySloping
Well Drained
over rock;Moderately wellto imperfectlydrained overfine grainedmaterial
None 2 to 4 Gullies and
Debris TorrentGullies
II to IV Stable
to Unstable
CfColluvialFan
Rock rubble(angularfragments);Some finegrained matrix
>3mGently toSteeplysloping
Well Drained None 3 to 4Active ColluvialFan
IV PotentiallyUnstable toUnstable
Ca ColluvialApron
Rock rubble(angularfragments);Some fine
grained matrix
>3m Gently toSteeplySloping
Well Drained None 3 to 4 ActiveCoalescingColluvial FansformColluvial
Apron
IV PotentiallyUnstable toUnstable
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Map
Symbol
Terrain
Unit
Texture Thickness Topo-
graphy
Soil Drainage Permafrost Slope
Class(es)
(After
Howes &
Kenk, 1997)
Mass Wasting
Features
Comments Stability
Rating (After
Forest
Practice Code)
Ds Debris Slide Highly variable(depends onsourcematerial);Ranges fromfine to coarserock rubble
>3m Gently toSteeplySloping
Well toImperfectlyDrained
None 3 to 4 Old Debris Slide IV Unstable
Ls Landslide Angular rockrubble
>3m Moder-ately toSteeply
Sloping
Well Drained None 4 Old Landslide IV Unstable
Dt DebrisTorrent
Gully
Variable; bothcoarse and fine
debris
Variable;Mostly>3
m
Moder-ately to
SteeplySloping
Well Drained None 3 to 5 Active DebrisTorrent Gully
Debristorrent Gully
ends in Fan
IV Unstable
Lv LacustrineVeneer
Silt, Sand &Clay
3m Level toGentlySloping
Moderately Wellto PoorlyDrained
PossibleUnderOrganicCover atHigherElevations
1 to 2 None I Stable
Fv FluvialVeneer
Gravel (roundedto sub-rounded);Some sand
&fines; PossibleMoraine atDepth
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Map
Symbol
Terrain
Unit
Texture Thickness Topo-
graphy
Soil Drainage Permafrost Slope
Class(es)
(After
Howes &
Kenk, 1997)
Mass Wasting
Features
Comments Stability
Rating (After
Forest
Practice Code)
Fb FluvialBlanket
Gravel (roundedto sub-rounded); Some
sand &fines;PossibleMoraine atDepth
1 to 3m
Level toGentlySloping
Well Drained None 1 to 2 None
Could be asource ofgood qualitygranularmaterial
I Stable
Fp Fluvial Plain Gravel(Rounded toSub-rounded;
Sand & Fines;Some bouldersand cobbles
>3m Level Well to PoorlyDrained
None 1 None May be wet I Stable
Ft FluvialTerrace
Gravel(Rounded toSub-rounded;
Sand & Fines;Some bouldersand cobbles
>3m Level toGentlySloping
Well Drained None 1 None May besource ofgood quality
granularmaterial
I Stable
Ff Fluvial Fan Gravel
(Rounded toSub-rounded;
Sand & Fines;Someboulders
andcobbles
>3m Level to
GentlySloping
Well Drained
but somesaturated zones
None 1 to 2 None; but maybe
activelydepositingmaterial
Crossed by
activedrainages;Seasonallywet
I Stable
FGv Glacio-
fluvialVeneer
Gravel(Rounded toSub-rounded),Sand & Fines;
possible
moraine atdepth
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Map
Symbol
Terrain
Unit
Texture Thickness Topo-
graphy
Soil Drainage Permafrost Slope
Class(es)
(After
Howes &
Kenk, 1997)
Mass Wasting
Features
Comments Stability
Rating (After
Forest
Practice Code)
FGt Glacio-
fluvialTerrace
Gravel(Rounded toSub-rounded),Sand & Fines
>3m Level toGentlySloping
Well Drained None 1 to 2 None Could be asource ofgood qualitygranularmaterial
I Stable
FGp Glacio-
fluvial Plain
Gravel
(Rounded toSub-rounded),Sand & Fines
>3m Level to
GentlySloping
Well to
Moderately WellDrained
None 1 to 2 None Could be a
source ofgood qualitygranularmaterial
I Stable
FGu UndulatingGlaciofluvial
Gravel(Rounded toSub-rounded).
Sand & Fines
>3m Gentlyrolling toundu-
lating
Well toModerately WellDrained
None 1 to 2 None Could be asource ofgood quality
granularmaterial
I Stable
FGh Hummocky
GlaciofluvialGravel(Rounded toSub-rounded).Sand & Fines
>3m Humm-ocky
Well toModerately WellDrained
None 1 to 4 None Could be asource ofgood qualitygranularmaterial
I Stable
FGf Glaciofluvial
Fan
Gravel
(Rounded toSub-rounded).Sand & fines;Some boulders& cobbles
>3m Gently
Sloping
Well Drained None 1 to 2 None Could be a
source ofgood qualitygranularmaterial
I Stable
LGp Glacio-
lacustrinePlain
Silt, Clay &sand
>3m Level toGentlySloping
Moderately Wellto PoorlyDrained
PossibleUnderOrganicCover atHigherElevation
1 to 2 None I Stable
L Gt Glacio-lacustrineTerrace
Silt, Clay &sand
>3m Level toGentlySloping
Moderately Wellto PoorlyDrained
PossibleUnderOrganicCover atHigherElevation
1 to 2 None Sideslopeson terracecould beunstable
I to III Stable toPotentially
unstable onterracesideslopes
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Map
Symbol
Terrain
Unit
Texture Thickness Topo-
graphy
Soil Drainage Permafrost Slope
Class(es)
(After
Howes &
Kenk, 1997)
Mass Wasting
Features
Comments Stability
Rating (After
Forest
Practice Code)
Mv MoraineVeneer
Till matrix isprimarily silt,sand & clay;
Coarsefragments at>2mm;Subangular to
sub-roundedand comprise
30% of till
2mm;
Subangular tosub-roundedand comprise
30% of till
1 to 3m Reflectsunderlyingunit
Moderately Wellto Well Drained
None 1 to 4 May have masswasting featureson steeper slopes
I to IV Stableto PotentiallyUnstable
Mp MorainePlain
Till matrix isprimarily silt,sand & clay;Coarsefragments at
>2mm;Subangular tosub-roundedand comprise
30% of till
>3m GentlySloping
Moderately Wellto Well Drained
None 1 to 3 None I Stable
Mm RollingMoraine(Drumlins)
Till matrix isprimarily silt,sand & clay;Coarse
fragments at>2mm;Subangular to
sub-roundedand comprise30% of till
>3m Rolling tolinear
Well drained onupper slopes ofridges; Some
poorly drainedareas betweenridges
None 1 to 4 None I to II Stable
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MAP UNIT EXAMPLE
302 = Polygon Number
tMb (Slope Class 2; tMb Terrain Symbol)2 IsR IsR till over limestone
w Soil Drainage11 Slope Stability Class (Stable)
SLOPE CLASS(After Howes & Kenk, 1997)
Class % Degrees1 0-5% 0-32 6-26% 4 -15
3 27-49% 16 - 264 50-70% 27 -355 >70% >35
OTHER DESCRIPTIVE LEGEND TABLES BC TERRAIN MAPPING GUIDELINES
TERRAIN CLASSESTEXTURAL TERMS
LANDFORM TERMSGEOMORPHOLOGICAL PROCESS TERMS (ACTIVE AND INACTIVE)
MASS WASTING TERMSROCK TERMS
CRITERIA FOR SLOPE STABILITY INTERPRETATION