2.2 Perform Soil/ Geotechnical and Geological Analysis Flashcards
What are the three types of rocks?
Sedimentary, Igneous, Metamorphic
Soil formation process creates layers called
Horizons
What are the soil horizons in layers?
0, A, B, C, D
O horizon
Organic matter in recognizable form, including leaves and partially decomposed matter
A horizon
Topsoil layer. Heavy non-recognizable organic matter mixed with minerals.
B Horizon
Subsoil. Nutrients left by rain water leaching, hardpans & clay pans develop here.
C Horizon
Partially weathered rock fragments; Represents the unconsolidated material that has not been affected by the soil formation process
D horizon
Bedrock or Ledge. `
Used to determine the amount of nutrients in the soil
Soil test
Summary report of the exploration of the subsurface soils and how they are to. be used as construction materials
Geotechnical Reports
What percentage of clay soils must have clay particles?
35-40%
Capacity of soil to support loads applied to the ground. Maximum average contact pressure between a structure and the soil surface on which it rests that the soil can support without failure
Bearing capacity
Bearing Capacity (low to high)
Clay (1-2 tons/ sqft) Silt (1.5-3) Sand (loose, 2-3) Gravel (loose, 4) Sand-gravel (compact, 6) Well graded, well compacted clayey sand and gravel (10) Sedimentary rock (15) Foliated rocks (40) Massive bedrock (100)
If there is presence of significant ammounts of water in the soil, what does it do?
Lowers the bearing capacity (especially in clays and silts).
It lowers the frictional forces
Very strong when dry, but become. mushy when saturated with water
Clay soils
Soil types smalles to largest
Clay (< 0.002mm)
Silt (0.002 - 0.05 mm)
Fine Sand (0.05-0.5 mm)
Coarse Sand (0.5-2.0 mm)
Describe Sandy Soils
Over 45% Sand Drains quickly Light weight Non-expansive Erodable
Describe Silty Soils
Over 40% silt
Small grain size
Moderate permeability
Highly erodable
Describe Clayey Soils
35-40% clay
Lowe permeability or impermeable
Heavy weight
Expansive: heaves, shrinks (swells when wet, shrinks when dry)
Low water availability at low moisture content
Collodial content describes presence of clay particles in samples
Erodable to highly erodable
Suspension of finely divided particles in a dispersing medium; particles do not rapidly settle out of suspension and are not readily filtered
Colloid
Describe Loam Soils
Less than 40% clay with a good particle size distribution
HIghly valuable agricultural soil
Very good drainage, moderately permeable, high water holding capacity
Slight erosion potential, 0-3% slope
Highly fertile
Easily worked
Soil amendment used to improve soil structure. Reduces salt toxicity in soils that are heavily irrigated. Provides sulfur and calcium to the soil and improves permeability. Does not significantly affect soil pH
Gypsum
What percentatge of moisture is best when needing to till or compact?
8-15%
Low pH
Usually have a high percentage of organic matter
Often associated with high rainfall
Acidic soils
Reasons for having acidic soils
- Rainfall and leaching
- Acidic parent material (granite)
- Organic matter decay
- Harvest of high yielding crops
What happens in wet climates & how does that create acidic soils?
Rainfall leaches a soils basic elements (calcium, magnesium, sodium, potassium) over time, and are replaced with acidic elements. High yielding crops rapidly absorb basic elements
High ph 7-14
Heavy in salts and other solutes
Usually associated with low rainfall
Alkaline/ Basic
Reasons for having basic soils?
- Soil is derived from a basic parent material such as limestone
- Located in a climate where the alkaline elements are not leached out by rain
Amendments to make soils less acidic
Lime
Pine needles
Organic material
Amendments to make soil less basic
aLuminum sulfate
sulfur
Best soil for plants?
6.5-7.5
List of Macronutrients
Nitrogen Phosphorus Potassium Calcium Magnesium Sulfur
MACRO NUTRIENT
Responsible for the vegetative growth of plants above ground.
Rich dark green foliage
Helps seed and fruit production
If deficient, plant tends to have a pale yellowish color (chlorosis), have a stunted appearance, develop thin, spindly stems. Lower leaves more affected.
Natural sources come from alfalfa meal, manure
Nitrogen
MACRO NUTRIENT
Promotes healthy strong roots, fruit and flower development, and greater resistance to disease. Enhances photosynthesis, root growth.
If deficient, plant is usually stunted, thin stemmed, and spindly. Foliage is often red or purple.
Natural sources include rock phosphate and bone meal
Phosporous
MACRO NUTRIENT
Helps plants resist diseases, protects them from the cold and protects during dry weather by preventing excessive water loss.
Plays a critical role in reducing the loss of water from leaves and increases the ability of roots to take up water from the soil.
Helps with environmental stresses
Signs of deficiency are tips and edges of oldest leaves begin to yellow and die (burned on tthe edges)
Natural sources include potassium sulfate, granite dust, wood ash
Potassium
MACRO NUTRIENT
Essential part of cell wall structure, provides for normal transport and retention of other elements as well as strength in the plant
Deficiency symotoms: deformed tips of leaves and little root growth
Calcium (think strength of bones)
MACRO NUTRIENT
Essential for photosynthesis. Activates many plant enzymes for growth
Deficiency symptoms: yellowing of leaves, purple leaf margins
Magnesium
MACRO NUTRIENT
Essential for production of protein. Helps in chlorophyll formation. Improves root growth and seed production. Helps with vigorous plant growth and resistence to cold
Deficiency symptoms: yellow and brown leaves
Sulfur
What are the 6 micronutrients?
Iron Maganese Zinc Copper Boron Molybdium
Surface of clay particles and organic matter are negatively charged and as such are capable of storing and supplying plant nutrients, which are positively charged.
Once mineral cations are absorbed onto soil particle surfaces, they are less likely to leach.
A high number of this indicates high soil fertility
Cation Exchange Capacity (CEC)
Soil Cation Exchange Capacity generally ____ as pH ____. Acidic soils tend to not have a high a CEC.
Increases, increases
Formed by the cooling of liquid magma (molten rock).
Two types:
extrusive - rock cools quickly when brought to surface; fine grained (ex. basalt)
intrusive - “ “ slowly “ “ ; coarse grained (ex. granite)
igneous
Formed by sedimentation of material at the earth’s surface and within bodies of water. Based on their depositional mode
Examples include Conglomerate (mechanically eroded), Sandstone, shale, and siltstone (mechanically eroded)
Limestone (chemically precipitated)
Sedimentary
Transformed from other rock materials in response to pressure or temperature
Two types:
- Foliated - distinctive layering (ex. gneiss and slate)
- non-foliated - (ex. Quartzite and marble)
Metamorphic
Movement of sand along a coastline due to wave and tidal action
Litoral drift
Blue or gray color of soil
Lack of air in soil / poor drainage
Yellow and red color of soil
Good drainage! Caused by iron oxides
Light colors in upper soil
Nutrient and iron leaching due to high percolation rates, or high levels of calcium carbonates
Dark colors in the surface layer of soil
Presence of organic matter
Evaluations of risk for conditions of possible environmental contamination, usually performed as part of a commercial real estate transaction.
Under federal law, a landowner is liable of environmental conditions on his property whether they had knowledge or not.
Usually occurs before purchase of land
Environmental Site Assesment (ESA)
Walk through of the site typically using a checklist that conforms to ASTM E-1528.
Performed by a site professioinal.
Transaction Screen
