Assessing Soil Characteristics andLimitations 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
Soil Assessment and Visualization: GIS and Database • Soil characteristics are particularly important in pipelineTopsoil Segregation construction Special Soil •FERC Resource reports: RR6 and RR7 Handling •EIS preparation •Identification of construction- related issues Stony/Rocky Visualization
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
Soil Properties and Interpretations DatabaseNRCS 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
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
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
Queries Reduce Data and Combine Specific Properties and Limitations Example Droughty Soils Expression Builder Conditional statements“Texture is coarser Mathematical statementsthan sandy loamand drainage classis drier thanmoderately well”Complex queriescan be developed Tables or queriesthat incorporatemathematical andconditionalstatements Selected fields
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)
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.
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
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 402.230A 402.230 402.336 0.116 MP 403B 402.336 402.721 0.385 0.116 Miles 0.385 Miles
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 0.116MP 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.
Consolidation Queries Accumulate Data From Property Specific Queries Milepost Query Selected fieldsThe consolidation query builds a table of soil limitations by milepost for directuse of data or summarized as pivot tables directly in Access or Excel
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.
Ins, Outs, and Seeing What You’ve Got (2)Database queries by NRG Soil Scientist relates soil limitations for specific soils by Milepost incrementTopsoil Depth, Slope, wet, organic, rocky, bedrock, caving slump hazards
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.
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.
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 dominantConsociation: 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.
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?
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
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.
Demonstration QueriesAccess Front EndRelationships Pivot Table Summaries Tables