_PERMIT FILE - M2000052

• Permit No: M2000052
• IBM Index Class Name: Permit File
• Doc Name: MAPS & EXHIBITS
• Media Type: D
• Archive: No

U.S. DEPARTMENT OF AGRICULTURE PAGE 2 OF 2
NATURAL RESOURCES CONSERVATION SERVICE O1/18/00
SOIL FEATURES
Endnote -- SOIL FEATURES
This report gives estimates of various soil features. The estimates are used in land use planning that involves
engineering considerations.
Depth to bedrock is given if bedrock is within a depth of 5 feet. The depth is based on many soil borings and on
observations during soil mapping. The rock is either "Soft" or "Hard". If the rock is "Soft" or fractured, excavations
can be made with trenching machines, backhoes, or small rippers. If the rock is "Hard" or massive, blasting or
special equipment generally is needed for excavation.
Cemented pans are cemented or indurated subsurface layers within a depth of 5 feet. Such pans cause difficulty in
excavation. Pans are classified as "Thin" or "Thick". A -Thin-' pan is less than 3 inches thick if continuously
indurated or less than 18 inches thick if discontinuous or fractured. Excavations can be made by trenching machines,
backhces, or small rippers. A "Thick" pan is more than 3 inches thick if continuously indurated or more than 18
inches thick if discontinuous or fractured. Such a pan is so thick or massive that blasting or special equipment is
needed in excavation.
Subsidence is the settlement of organic soils or of saturated mineral soils of very low density. Subsidence
results from either desiccation and shrinkage or oxidation of organic material, or both, following drainage.
Subsidence takes place gradually, usually over a period of several years. This report shows the expected initial
0sidence. which usually is a result of drainage, and total subsidence, which usually is a result of oxidation. Not
wn in the report is subsidence caused by an imposed surface load or by the withdrawal of ground water throughout
an extensive area as a result of lowering the water table.
Potential frost action is the likelihood of upward or lateral expansion of the soil caused by the formation of
segregated ice lenses (frost heave) and the subsequent collapse of the soil and loss of strength on thawing. Frost
action occurs when moisture moves into the freezing zone of the soil. Temperature, texture, density, permeability,
content of organic matter, and depth to the water table are the most important factors considered in evaluating the
potential for frost action. It is assumed that the soil is not insulated by vegetation or snow and is not artificially
drained. Silty and highly structured clayey soils that have a high water table in winter are the most susceptible to
frost action. Well drained, very gravelly, or very sandy soils are the least suscepcible. Frost heave and low soil
strength during thawing cause damage mainly to pavements and other rigid structures.
Risk of corrosion pertains to potential soil-induced electrochemical or chemical action that dissolves or weakens
uncoated steel or concrete. The rate of corrosion of uncoated steel is related to such factors as soil moisture,
particle-size distribution, acidity, and electrical conductivity of the sail. The rate of corrosion of concrete
is based mainly on the sulfate and sodium content, texture, moisture content, and acidity of the soil. Special
site examination and design may be needed if the combination of factors creates a severe corrosion environment. The steel
installations that intersect soil boundaries or soil layers is more susceptible to corrosion than steel in
installations that are entirely within one kind of soil or within one soil layer. For uncoated steel, the risk of
corrosion, expressed as "Low", "Moderate", or "High", is based on soil drainage class, total acidity, electrical
resistivity near field capacity, and electrical conductivity of the saturation extract.
For concrete, the risk of corrosion is also expressed as "Low", "Moderate". or "High". It is based on soil texture,
acidity, and amount of sulfates in the saturation extract.
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