Soils, Infiltration, and On-site Testing

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Soils, Infiltration, and On-site Testing

• Presented by
• Mr. Brian Oram, PG, PASEOWilkes
  UniversityGeoEnvironmental Sciences and
  Environmental Engineering DepartmentWilkes -
  Barre, PA 18766570-408-4619
• http//www.water-research.net

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Soils Defined

• Natural Body that Occurs on the Land Surface that
  are Characterized by One or More of the
  Following
• Consists of Distinct Horizons or Layers
• The ability to support rooted plants in a
  naturalenvironment
• Upper Limit is Air or Shallow Water
• Lower Limit is Bedrock or Limit of Biological
  Activity
• Classification based on a typical depth of 2 m or
  approximately 6.0 feet

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Another Definition of Soils

• A Natural 3 - Dimensional Body at the Earth
  Surface
• Capable of Supporting Plants
• Properties are the Result of Parent Material,
  Climate, Living Matter, Landscape Positionand
  Time.
• Soil Composed of 4 Components (mineral matter,
  organic matter, air, and water)

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Five Soil Formation Factors

• Organisms
• Climate
• Time
• Topography and Landscape Setting
• Parent Material

R
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Soil Food Web - Organisms

• Micro Macroscopic
• Decomposition of Organic Matter
• Animals Living in Soil
• Vegetation Types
• Human Activity
• Redoximorphic Feature Formation

Image Source The University of Minnesota, 2003
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Climatic Elements(Energy Precipitation)

• Annual and Seasonal Rainfall
• Temperature Range
• Biologic Production and Activity
• Weathering (Wind, Water, and Ice)
• Translocation of Material

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Climate and Soil Development
Image Source University of Wisconsin, 2002
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Geologic Time
Time
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Landscape and Relief(Soil Texture)
A- Sandy Texture andLoamy SandB- Sandy
Textures C- Clay Loam, Loam, Silt Loam
Image Source University of Wisconsin, 2002
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Landscape and Relief (Drainage)
Water MovementSoil DrainageLandscape
Configuration (Convex, Concave)ElevationWater
Movement
Image Source NJ NRCS, 2002
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Parent Material

• Geological Materials
• Minerals and Rocks
• Glacial Materials
• Loess (wind blown)
• Alluvial Deposits
• Marine Deposits
• Organic Deposits
• Influences
• Minerals Present
• Colors
• Chemical Reactions
• Water Movement
• Soil Development

Glacial Material
Bedrock
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Soil Horizons

• Layer of Soil Parallel to Surface
• Properties a function of climate, landscape
  setting, parent material, biological activity,
  and other soil forming processes.
• Horizons (A, E, B, C, R, etc)

Image Source University of Texas, 2002
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Soil HorizonsO- Organic Horizons

• Organic Layers of Decaying Plant and Animal
  Tissue
• Aids Soil Structural Development
• Helps to Retain Moisture
• Enriches Soil with Nutrients
• Infiltration Capacity function of Organic
  Decomposition

O Horizon
Dark in Color Because of Humus Material -
1,000,000 bacteria per cm3
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Soil HorizonsA Horizons Topsoil

• Mineral Horizon NearSurface
• Accumulation of OrganicMaterial
• Eluviation Process Moves Humic and Minerals from
  O Horizon into A horizon
• Ap - Plowed A Horizon
• Ab - Buried Horizon
• Soil dark in color, coarser in texture, and high
  porosity

A Horizon
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Soil Horizons E HorizonsAlbic Horizon (Latin -
White)

• Mineral Horizon NearSurface
• Movement of Silicate Clay, Iron, and Aluminum
  from the A Horizon through Eluviation
• Horizon does not mean a water table is present,
  but the horizon can be associated with high water
  table , use Symbol Eg (gleyed modifier)
• Underlain by a B (illuvial) horizon

E Horizon
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Soil Horizons B HorizonsZone of Maximum
Accumulation

• Mineral Horizon
• Illuviation is Occurring - Movement into the
  Horizon
• B Horizon Receives Organic and Inorganic
  Materials from Upper Horizons.
• Color Influence by Organic, Iron, Aluminum, and
  Carbonates
• Bw - Weakly Colored or Structured
• Bhs- Accumulation of illuvial organic material
  and sesquioxides
• Bs- Accumulation of sesquioxides
• Bt- Translocation of silicate clay
• Bx- Fragipan Horizon, brittle

Bhs Horizon
Bs Horizon
Bw Horizon
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Soil Horizons Bx and Bt Horizons
Horizons Indicate Reduced Infiltration Capacity
and Permeability
Bx B horizon with fragipan, a compact, slowly
permeable subsurface horizon that is brittle
when moist and hard when dry.Prismatic soil
structure, mineral coatings and high bulk density
Area of Highest Permeability along Prism Contact
Bt Clay accumulation is indicated by finer soil
textures and by clay coating peds and lining
pores
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C- HorizonsDistinguished by Color, Structure,
and Deposition

• Mineral Horizon or Layer, excluding Rock
• Little or No Soil-Forming
• May be Similar to Overlying Formation
• May be Called Parent Material
• Layer can be Gleyed
• Developed in Place or Deposited

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R- Horizons

• Hard, Consolidated Bedrock
• Typically Underlies a C Horizon, but could be
  directly below an A or B Horizon.

R Horizon
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Soil Hydrologic Cycle
Source Vepraskas, M.J, et. Al. Wetland Soils,
2001.
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Soil Drainage Class and Soil Group

• Soil Drainage Class - Refers to Frequency and
  Duration of Periods of Saturation or Partial
  Saturation During Soil Formation. There are 7
  Natural Soil Drainage Classes.
• Hydrologic Soil Group-Refers to Soils Runoff
  Producing Characteristics as used in the NRCS
  Curve Number Method. There area 4 Hydrologic
  Soil Groups (A, B, C, D).

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Group A and B
Group A is sand, loamy sand or sandy loam types
of soils. It has low runoff potential and high
infiltration rates even when thoroughly wetted.
Deep, well to excessively drained sands or
gravels and have a high rate of water
transmission. Root Limiting / Impermeable layers
over 100 cm or 40 inches
Group B is silt loam or loam.
It has a moderate infiltration rate when
thoroughly wetted. Moderately deep to deep,
moderately well to well drained soils with
moderately fine to moderately coarse textures.
Root Limiting / Impermeable e layers over 50 to
100 cm or 20 to 40 inches
Group A- Well Drained
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Group C and D
Group C soils are sandy clay loam. They have low
infiltration rates when thoroughly wetted and
consist chiefly of soils with a layer that
impedes downward movement of water and soils
with moderately fine to fine structure. Perched
water table 100 to 150 cm or 40 to 60 inches
root limiting 20 to 40 inches.
Group D soils are clay loam,
silty clay loam, sandy clay, silty clay or clay.
They have very low infiltration rates when
thoroughly wetted and consist chiefly of clay
soils with a high swelling potential, soils with
a permanent high water table, soils with a
claypan or clay layer at or near the surface and
shallow soils over nearly impervious material (
lt 20 inches).
Group D - Poorly DrainedHighest Runoff Potential
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Definitions
Infiltration - The downward entry of water into
the immediate surface of soil or other
materials. Infiltration Capacity- The maximum
rate at which water can infiltrate into a soil
under a given set of conditions. Infiltration
Rate- The rate at which water penetrates the
surface of the soil and expressed in cm/hr,
mm/hr, or inches/hr. The rate of infiltration
is limited by the capacity of the soil and rate
at which water is applied to the surface. This
is a volume flux of water flowing into the
profile per unit of soil surface area (expressed
as velocity). Percolation -Vertical and Lateral
Movement of water through the soil by gravity.
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Infiltration Rate and Capacity
Soil Factors that Control Infiltration Rate -
Vegetative Cover, Root Development and Organic
Content - Moisture Content - Soil Texture and
Structure - Porosity and Permeability - Soil
Bulk Density and Compaction - Slope, Landscape
Position, Topography
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Infiltration Rate (Time Dependent)
Decreasing Infiltration
Steady Gravity Induced Rate
Infiltration with Time Rate is Initially High
Because of a Combination of Capillary and
Gravity Forces
Final Infiltration Capacity(Equilibrium)-
InfiltrationApproaches Saturated Permeability
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Infiltration Rate (Moisture)
Infiltration Decreases with Time1) Changes in
Surface and Subsurface Conditions2) Change in
Matrix Potential3) Overtime - Matrix Potential
Decreases and Gravity ForcesDominate - Causing a
Reduction in the Infiltration Rate
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Measuring Infiltration Rate

• Flooding (ring) Infiltrometers
• Single ring
• Double ring
• Flooded Infiltrometers
• Tension Infiltrometers
• Rainfall-Runoff Plot Infiltrometers

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Measuring Infiltration Rate
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Single Rings Infiltrometers
Cylinder - 30 cm in DiameterDrive 5 cm or more
into Soil Surface or HorizonWater is Ponded
Above the Surface Record Volume of Water Added
with Time to Maintain a Constant Head Measures
a Combination of Horizontal and Vertical Flow
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Double Rings Infiltrometers
Outer Rings are 6 to 24 inches in Diameter (ASTM
- 12 to 24 inches)Mariotte Bottles Can be Used
to Maintain Constant HeadRings Driven - 5 cm to
6 inches in the Soil and if necessary sealed
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Other Infiltrometers
Ponded Infiltrometers
Tension InfiltrometerUnsaturated Flow Of Water
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Infiltration Rate by Soil Group/ Texture
Source Texas Council of Governments, 2003.
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Infiltration Rate Function of Slope Texture
Source Rainbird Corporation, derived from USDA
Data
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Infiltration Rate Function of Vegetation
Source Gray, D., Principles of Hydrology, 1973.
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Comparison Infiltration to Percolation Testing
Percolation Testing Over Estimated Infiltration
Rate by 40 to over 400
Source On-site Soils Testing Data, (Oram, B.,
2003)
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Infiltration and Rock Content (Oram, B. 2003)
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Infiltration (Compaction/ Moisture Level)
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Case 1 Myers Proposed Development Worcester
Township, Pennsylvania

• Abbottstown Silt Loam, Deep to Moderately Deep,
  Somewhat Poorly Drained
• Some Areas Shallow Depth to Firm Bedrock
• Signs of Erosion
• Low Surface and Near Surface Infiltration Rates
  Associated with Surface Smearing, Btx, Bx
  Horizons
• BC/ C /R Horizons Higher Infiltration Rate.

• Readington Silt Loam
• Deep Moderately Well Drained
• Low Infiltration Surface, Bd, and Btx
• High Infiltration in C and R Horizons

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Infiltration Rate Function of Horizon A, B, Btx,
Bt, C, RC/R Testing - Areas Fractured Rock
Source On-site Infiltration Testing - Mr. Brian
Oram, PG (2003)
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Case 2 Country View at Salford Salford
Township, Montgomery County, PA
Soil CrB2 Croton Silt Loam Deep, Poorly
Drained Diagnostic Features Bx, Bxg, Bt, R
(firm) Reported Infiltration Rate lt 0.2 to 2.0
in/hr Field Measured Rate 0.1 to 0.52
in/hr Primary Natural Drainage Depression
Storage, Swale Development, Throughflow Flow
Through Wetland Areas, Overland
Flow Predevelopment Conditions Unstable Stream
Banks, Overland Flow from Off Site
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Evaluation Infiltration

• Step 1 Desktop Assessment - GIS
• Review Published Data Related to Soils, Geology,
  Hydrology
• Step 2 Characterize the Hydrological
  SettingWhere are the Discharge and Recharge
  Zones?What forms of Natural Infiltration or
  Depression Storage Occurs?
• Step 3 On-Site Assessment
• Deep Soil Testing Throughout Site Based on Soils
  and Geological Data
• Double Ring Infiltration Testing
• How will water move through the site ?
• Step 4 Engineering Review and Evaluation
• Step 5 Additional Infiltration or On-site
  Testing
• Step 6 Final Design

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Soils, Infiltration, and On-site Testing

• Presented by
• Mr. Brian Oram, PG, PASEOWilkes
  UniversityGeoEnvironmental Sciences and
  Environmental Engineering DepartmentWilkes -
  Barre, PA 18766
• 570-408-4619
• http//www.water-research.net

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Horton Equation (1939)
Infiltration is a Function of Time as defined
by f(t) fc (fo fc)e-kt f(t)
infiltration rate for any time t from beginning
of infiltration fc infiltration capacityfo
initial infiltration rate at (t0) e 2.71 base
of natural log k is a measure of the rate of
decrease in infiltration rate(constant that
depends on soil type) Large Watershed
Application - Replaced by Philip and
Green-AmptHorton Method Used in EPA Storm Water
Management Model
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Green-Ampt Equation

• Green-Ampt model was the first physically-based
  model/equation describing the infiltration of
  water into soil. The model yields cumulative
  infiltration and the infiltration rate as an
  implicit function of time. The volume of
  infiltration was a function of
• Soil pores are saturated behind wetting front
• Wetting front moves in response to capillary
  forces and
• Darcys flow governs that headloss in the
  saturated zone.
• Approx. Equation f (A/F)B f infiltration
  rate, F - accumulative infiltration, and A and B
  are fitted parameters
• The Green-Ampt Model has been modified to
  calculate water infiltration into non-uniform
  soils by several researchers . In 1989, GALAYER
  was developed for heterogenous soils
• Models Available at http//www.epa.gov/ada/csmos
  /ninflmod.htmlhttp//www.bae.ncsu.edu/soil_water/
  drainmod/dmversions.htm

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Philip Equation (1960)
whereF total depth of infiltrated water in
mm.t time in seconds K hydraulic
conductivity in mm/sec m the average moisture
content of the soil to the depth of the wetting
front m0 initial soil moisture content -
based on API calculation or inputPot capillary
potential at the wetting front in mm Pot 250
log (K) 100 D1 depth of water on the soil
surface Takes into account the Ponding
Head Models Available at http//www.epa.gov/ad
a/csmos/ninflmod.html
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Soils, Infiltration, and On-site Testing

• Presented by
• Mr. Brian Oram, PG, PASEOWilkes
  UniversityGeoEnvironmental Sciences and
  Environmental Engineering DepartmentWilkes -
  Barre, PA 18766
• http//www.water-research.net