• there is a flood hazard.  Avoid homes in a flood plain unless there is adequate flood protection.
• drainage is a problem.
• the soils have high shrink-swell properties.
• slope and unstable soil make erosion and soil movement a major problem.
• soil conditions exist that corrode pipes easily and require frequent replacement.
• grading and soil removal was extensive.  Was the surface soil replaced?
• the soil properties are favorable for lawn, shrubs, trees, flowers, and vegetables without extensive soil modification.

     This contest is designed to emphasize the importance of soils and their limitations for homesites.  The importance of a soil's suitability for parks, playgrounds, roads, streets, and other uses can also be considered.  Many of the properties important for agricultural uses are also important for urban uses.  While the properties are the same, a different set of criteria is used to evaluate urban uses.

Defining Limitations
     Soils have limitations in use depending on their inherent properties.  In homesite evaluations, the soils are rated as having slight, moderate, severe, or very severe limitations as follows:
     Slight limitations -- Soils or sites have properties favorable for the planned use and present few or no problems. Low maintenance can be expected.
     Moderate limitations -- Soils or sites have one or more properties considered somewhat restrictive for the planned use.  Limitations may be overcome or modified with special planning, design, treatment, or maintenance.
     Severe limitations -- Soils or sites have one or more properties unfavorable for the planned use.  Limitations are very difficult and expensive to modify or overcome for the desired use.  A severe rating means that extensive, costly work needs to be done to overcome the soil limitations for the use desired.
     Very severe limitations -- Soils or sites have features so unfavorable for a particular use that overcoming the limitations is very difficult and   extremely expensive and generally should not be used for the purpose being rated.

Defining Land Uses
     Limitation ratings will be made for four homesite uses:  (1) foundations for buildings, (2) lawns and landscaping, (3) septic system absorption field, and (4) sewage lagoon.  Ratings for other uses can be made but are not included in this contest.
     Foundations for buildings -- This determination reflects the suitability of the soil to support buildings.  Some important soil properties that affect building foundations are soil depth, slope, shrink-swell potential, water table, and flooding.
     Lawns and landscape plantings -- This rating reflects the use of the soil for growing lawns, shrubs, trees, and vegetable gardens.  The important soil properties are those that affect establishment and maintenance of planting.  They include texture, permeability, soil depth, runoff, water table, plant response when fertilizer is applied, and absence of toxic materials such as salts.
     Septic tank absorption field -- Subsurface systems of tile or perforated pipe that distribute waste water (effluent) from a septic tank into the soil for purfication.  Properties and features that affect the absorption of the effluent are permeability, water table, soil depth, and flooding.  Stones and shallow depth may interfere with installation and excessive slope can affect the operation of the system.
    Sewage lagoon -- A dug pond used to hold sewage solids for bacterial decomposition and effluent evaporation is a sewage lagoon.  Consideration of the soils ability to impound water and for use as embankment material must be made.  Soil properties affecting sewage lagoons are soil texture, permeability, soil depth, water table, slope, and flooding.

Factors Affecting Suitability
Texture
     This refers to the texture of the surface soil.  Surface texture is not a factor for septic systems and sewage lagoons because lagoons and lateral lines are dug below the surface.
     Coarse:  Moderate limitations for all uses -- May require stabilization with organic material and/or loamy topsoil to improve moisture and nutrient holding and supplying capacity for desired plant growth.  Water and wind erosion may be a problem during construction.
     Moderately Coarse, Medium, Moderately Fine: None to slight limitations for all uses -- Care should be exercised during construction to be sure the surface soil is not covered by less desirable material.
     Fine:  Severe limitations for all uses, except none to slight limitations -- For sewage lagoons.  Soil is sticky when wet, hard when dry, and difficult to work with in flower beds and gardens.  The soils crack when dry, swell when wet, requiring frequent and low rate of watering for plant growth.

Permeability
     This refers to the rate water or air moves through the most restricted layer in the soil.  This may be considered as internal drainage.  Laterals for septic systems may be located below such layers in some soils. Final design should be based on detailed study of permeability, seasonally high water tables, and a standard percolation test to determine infiltration rates where soils are slow or very slowly permeable.  These investigations are  important factors in deciding between septic tank absorption fields, sewage lagoons, or a community sewage system.  Generally, soils unsuited for septic systems are much better suited for lagoons.  For septic systems, evaluate the permeability of soil layers below 30 inches and for sewage lagoons evaluate the layers between 12 to 60 inches.
 
 

Special note: For contest purposes, permeability will be determined from the subsoil texture box.

     Rapid:  Slight limitations for septic system absorption field.  Moderate limitations for lawns and landscape planting.  Severe limitations for sewage lagoons.  The soils are coarse textured.  Permeability is more than 2 inches per hour.  If the permeability is greater than 6 inches per hour, seepage from lagoons will occur and make it difficult to maintain adequate water depth and could contribute to ground water pollution.  Septic systems may not adequately filter waste water.  When the permeability is greater than 6 inches per hour, it is considered a very severe limitation for both septic systems and lagoons.
     Moderate:  Moderate limitations for septic system absorption field and sewage lagoons.  The soils are moderately coarse and medium textured with weak prismatic to blocky and strong granular structure.  Permeability ranges from 0.6 to 2 inches per hour.  None to slight limitations for lawns and landscape plantings.
     Slow:  Severe limitations for septic system absorption field.  Soils are generally moderately fine textured with a subangular blocky structure.  Problems are generally similar to the very slowly permeable soils but the modifications required for use are less intense.  Permeability ranges from 0.06 to 0.6 inches per hour.  Percolation tests should be run to design a suitable septic tank disposal field.  At the .06 inch per hour rate (1 1/2 inches per day), the cost of modifications and size of filter field would be prohibitive.  Limitations would be none to slight for sewage lagoons and moderate for lawns and landscape plantings.
     Very Slow:  Very severe limitations for septic system absorption field.  Permeability is less than 0.06 inches per hour.  This would require a prohibitively large field of laterals or costly modifications would be necessary to effectively dispose of the effluent.  Septic systems are generally  not recommended. None to slight limitations for sewage lagoons.  Subsoils are fine textured and break into sharp angular blocks or clods that are plastic and sticky when wet and very hard when dry.  The clods are usually coated with clay which restricts water movement.  Severe limitations for lawns and landscape plantings.

Soil Depth
     This refers to the vertical depth of a soil to bedrock such as sandstone, limestone, or consolidated clays that restrict roots and excavations.  Severity of limitations because of depth vary greatly for different uses.  Table 6 is a guide for evaluation of soil depth for homesite uses.

Slopes
     This refers to the steepness of the surface or the vertical rise or fall over 100 feet of distance, expressed in percent.  Broader and different slope ranges apply to homesite use considerations than normally apply to considerations for agricultural uses.  Table 7 will aid in interpretation of the slope condition for homesite evaluation.

Erosion
     Erosion of the soil can increase the expense of landscaping and require additional topsoil to be brought onto the site.  Severe gullies will impose additional limitations on septic system absorption fields.
     None to Slight and Moderate:  None to slight limitations for any use.
     Severe:  Moderate limitations for any use.
     Very Severe:  Severe limitations for any use.  Usually severely gullied areas require much filling and leveling, extra expense on septic system absorption field, and extensive modification for flower beds, lawns, etc.

Surface Runoff
     This is generally a factor of importance in connection with drainage, permeability, and erosion.  Special attention needs to be given to surrounding areas.  Runoff from adjacent areas onto building sites and the possibility of ponding water around the building foundation need consideration.  Surface runoff is not a factor for sewage lagoons because they will be protected from outside water.

     Rapid:  Occurs on slopes above 5% except on deep sands where runoff would be slow.  Severe limitations requiring care to maintain and to prevent erosion on lawns and gardens.  None to slight limitations for foundation for buildings and septic systems absorption field.
 
    Moderate:  None to slight limitations for foundations and septic systems. Moderate limitations for lawns and landscape plantings.  Occurs on slopes of 3% to 5%.

     Slow:  Occurs on nearly level to very gently sloping areas (0 to 3%) and deep sands.  Moderate limitations may require modification for building foundations and special design of septic system absorption field.  On deep sands, slow runoff would not present any limitations.  None to slight limitations for other uses.

 Shrink-Swell
     This factor is implied in the permeability, texture, and mineralogy of a soil.  Because it is important in foundation design, it should have special consideration.  The most clayey layer in the profile is generally considered in shrink-swell limitations.  Shrink-swell is not generally a factor for lawns and landscape plantings.
     Low:  Coarse and moderately coarse textured soils have none to slight limitations for all uses.
     Moderate:  Medium and moderately fine textured soils have moderate limitations for all uses, except none to slight for sewage lagoons.
     High:  Fine textured soils have severe limitations for all uses, except none to slight for sewage lagoons.

Water Table
     The internal wetness of an area is influenced by most of the factors previously discussed.  Generally, internal drainage is a reflection of permeability.  However, the presence and depth to a water table is more a reflection of climate, season, and landscape position.  It must be evaluated on the basis of depth to the seasonal high level and the permanency of the water table.  This requires study during different times of the year and under differing climatic conditions.

For contest purposes, water table depth will be given information.  A water table is: deep if it is greater than 72 inches. moderately deep if it is between 40 to 72  inches. shallow if it is less than 40 inches.