The use of NRCS SSURGO2 GIS to evaluate soil limitations along linear rights-of-way is presented. International Conference Environmental Concerns in Right-of-Way Management, Portland Oregon.

1. Assessing Soil Characteristics and
Limitations along Pipeline rights-of-
Way using GIS Spatial and Attribute
Data integration and Management
Jim Arndt, Ph.D., Senior Natural Resource
Specialist
Joe Flannery, GIS Manager

2. Soil Assessment and Visualization: GIS and
Database
• Soil characteristics are
particularly important in pipeline
Topsoil Segregation construction
Special Soil
•FERC Resource reports: RR6
and RR7
Handling
•EIS preparation
•Identification of construction-
related issues
Stony/Rocky
Visualization

3. Old Surveys, New Surveys, Better Surveys
Old Surveys “New” Surveys GIS Surveys (SSURGO2)
• Dated • Current • Easier to use
• Inconsistent • Consistent • Cheap (once made)
Format format • Easily distributed
• Hard to use • User friendly • Availability close to 100%
• Agricultural • Broader • Engineering-related data
emphasis audience (Not • Many engineering
• Soil Professional just Agriculture) interpretations
emphasis • Difficult for
large projects

4. Soil Properties and Interpretations Database
NRCS SSURGO2 Database is Available to Anyone with a Computer!
 Download in Access format
from Web.
 Canned interpretations.
 A user-friendly forms input
structure.
 One database – All counties
for specific project
http://soildatamart.nrcs.usda.gov/  Use specific queries
easily developed

5. Components of a SSURGO2 Soil Survey: Soil Attributes
 Access template
 Generic, but can be specific
to state
 Form populates tables
automatically
 Front-end GUI Query Format
 User-friendly front end
(access database)
 Database: Tables
 Physical and Chemical
Properties
 Interpretations
 User defined queries

6. The SSURGO2 Database in Microsoft Access
Less Specific More Specific
 Map unit and legend tables Soil Survey Area Component Series
connect to spatial map data Map Units Soil Profile Layers
 Component tables provide
physical and chemical
characteristics of the whole soil, and
interpretations for various uses.
 Layer Tables provide physical
and chemical characteristics for
each soil layer.
Key Field
 Tables are linked in the Links
database by Common (key) 1 to ∞
Relationship
Fields.
 One to Many relationships

7. Queries Reduce Data and Combine Specific Properties and Limitations
Example
Droughty Soils
Expression Builder
Conditional statements
“Texture is coarser Mathematical statements
than sandy loam
and drainage class
is drier than
moderately well”
Complex queries
can be developed Tables or queries
that incorporate
mathematical and
conditional
statements Selected fields

8. Components of a SSURGO2 Soil Survey (2)
 Maps
 Soil polygons in ESRI
Arcview/Arcmap format
 Attributed with labels
indicating soil survey area
and map unit
 Digital Soil Map Unit
polygons go through
extensive QA/QC
 Relates to polygon line
placement, not soil
boundaries
 Basemaps in GIS – can be very high resolution (1-foot pixel)
 Use-specific basemaps (e.g. geology, hydrology, USGS
quadrangles)

9. Soil Associations
Soil Map Units Hayden Hayden
(storden)
Consociations Dickman
Minneiska
Complexes
Estherville
Waukegan/
Waukegan/ Kasota
Dickman Kasota
 Association is block Sparta
diagram. Shows what Biscay
soils can be expected. Sparta
 Soil map Units (dotted
lines) show where
specific soils are
consistently found.
 CONSOCIATION.
Some soils map units  Inclusions. Minor soils found in soil map units.
consist of one dominant Cannot be incorporated into assessment as data
soil type. Easy to assess. in the database is not provided for inclusions.
 COMPLEX. Two or  RESULT. Minor amounts of different soils can
more soils to mixed up be found in any soil map unit. A TOOL: NO
to map separately GUARANTEES OF PURITY.

10. Important Soil Limitations Covered
 Whole Map Unit (One or more dominant soils)
 Prime Farmland
 Highly Erodible Land
 Whole Component Soil Series (One Soil)
 Bedrock: Presence and hardness (soft; rippable, hard; blast or other)
 Slope Class: 0-5, 5-8, 8-15, 15-30, >30
 Hydric Soils: Component of wetland, if drained possibility of draintile,
generally high water table in any event
 Water Erodible, Wind Erodible, Droughty. NRCS classifications, affects
stormwater management, reclamation
 Depth and persistence of the water table. Ponded, flooded, saturated
 Soil Profile Layers (Up to seven horizons, generally to five feet)
 Topsoil depth: 0-6, 6-12, 12-18, >18, Deep Peat, Shallow Peat.
 Surface Stones: >5% on top soil horizon.
 Profile Stones: >5% average in profile (51 inches).
 Gradation of Sandy Soils – Wet and Dry. Poorly, moderately, and well graded based
on Texture classification (USDA, AASHTO, UNIFIED)
 Chemistry: pH, saline soils, sodic soils
 Texture: Triple lift candidates, contrasting sub-soils

11. Normalizing Map Unit Component
Soil Consociation (A)
Composition To Remove Inclusions
•92% Soil 1
•8% Soil 2
•92/92 = 1.0 Decimal
Soil Complex or Fraction Dominant Soil
Undifferentiated (B)
•55% Soil 1
•40% Soil 2 (2) 40%
•5% Soil 3 (1) 55%
•55/(55+40) = 0.58 Decimal
Fraction Soil 1
•40/(55+40) = 0.42 (1) 92%
Decimal Fraction Soil 2
•Inclusions removed
(2) 8%
(3) 5%

12. Determining Crossing Lengths for Map Unit Components In
Arcmap GIS
 The proposed route feature is first prepared in the GIS by calibrating it with real-
world length or to a predefined milepost/stationing system.
 Feature crossing tables are then created by using the “Locate Features Along
Route” tool in the GIS. The tool computes the route and measure information at
the geometric intersection of polygon data and route data.
Soil FMEAS TMEAS Crossed 402.336 402.336
map
402.721
Unit
402.230
A 402.230 402.336 0.116
MP 403
B 402.336 402.721 0.385
0.116 Miles
0.385 Miles

13. Determining Crossing lengths for Map Unit Components
Soil Consociation (A): 0.116 * 1.00 Soil 1 = 0.116
Soil Complex or Undifferentiated (B): 0.385 * 0.58 Soil 1 = 0.223
0.385 * 0.42 Soil 2 = 0.162
Soil FMEAS TMEAS Crossed
402.336 402.336 Map
Unit
402.721
402.230 A 402.230 402.336 0.116
MP 403 B 402.336 402.721 0.385
Soil 1 0.223
Soil 2 0.162
In GIS soil complexes consist
0.116 Miles of two overlapping polygons
0.385 Miles with hatching indicating the
level of the limitation.

14. Consolidation Queries Accumulate Data From Property
Specific Queries
Milepost Query
Selected fields
The consolidation query builds a table of soil limitations by milepost for direct
use of data or summarized as pivot tables directly in Access or Excel

15. Ins, Outs, and Seeing What You’ve Got (1)
 GIS group provides crossing tables with upstream and downstream
mileposts for all soil map units crossed. ~5000+ on 300+ mile
projects
 The database is used to separate map units into component soil
series and calculate map unit composition excluding inclusions.
 The database then calculates soil component crossing length for
each map unit.

16. Ins, Outs, and Seeing What You’ve Got (2)
Database queries by NRG Soil Scientist relates soil limitations for specific
soils by Milepost increment
Topsoil Depth, Slope, wet, organic, rocky, bedrock, caving slump hazards

17. Pivot Tables Summarize Data by County, Spread
 Used in
Resource
reports, pre-
filing
applications,
project bid
documents
 Detailed tables
used by
contractors to
identify areas
of particular
limitations.

18. Ins, Outs, and Seeing What You’ve Got (3)
Soil Boundary Topsoil Depth Sandy Grade Wet Sandy Hydric
Soil Limitations visualized in GIS with limitation classes.
•Topsoil depth affects construction width, storage needs, regulatory compliance.
•Sandy soil affects constructability.
•Wet and Sandy soils subject to slumping, affects construction width needs.
•Hydric soil affects construction techniques, regulatory compliance.
Soil limitations visualized in GIS: Spatially correct.

19. Visualizing Properties for Soil Complexes
 Consociations (one dominant soil) are separated in the database into one layer
 Complexes are separated out as one layer for each soil component and merged
 Hatches with transparent backgrounds identify overlapping polygons with varying soil
properties
Complex: Three dominant
Consociation: One Dominant soils.
Soil, >12-18 inch topsoil,
representative value 17 inches Soil 1: >18 Soil 2: Shallow Soil 3: Deep
inches Organic Organic
Using the “Identify” tool in Arcmap will
bring up information on component
percentages for each soil. Tables provide
all of the values.

20. Ins, Outs, and Seeing What You’ve Got (4)
ID tool in Arcmap provides all data for a single map unit in one view.
BUT, how do you use this in the field?

21. Use-specific Soil Interpretation Alignment Sheets
Mapbook procedure: Exactly Same Views
Soil map units, 5-
foot contours, tract
numbers
Topsoil depth
increment, SSURGO2-
representative depth
Compaction-
prone soils
Any combination of soil
limitations can be
depicted

22. Caveats
 System is a planning tool to better prepare for construction.
 Data only as good as the soil survey.
(note scale is 1:24,000, best we have).
 Inclusions not accounted for.
Inclusions are small amounts of dissimilar soils not mapped within the unit.
Generally account for 5-10%, frequently hydric.
Small amounts of wet areas and soils with contrasting properties are possible, but
should not be present in significant amounts.
 Will not substitute for field assessments.
 Soils map unit complexes are difficult to work with.
Complexes consist of two to three soils not specifically mapped out within the map
unit. Data provide evaluation of the amount of each soil type within map unit, but
give no indication of where the soils will be found.

23. Demonstration
Queries
Access Front End
Relationships Pivot Table Summaries
Tables

24. Questions