Land Judging for Farms and Homesites
Factors Affecting Suitability

Surface Texture - Surface texture is not a factor for sewage lagoons because they are dug deep into the subsoil. Most of the surface soil is used in making the berm around the lagoon.

Clayey (fine): Severe limitations - for all uses other than sewage lagoons. Soil is sticky when wet, hard when dry, difficult to work when used for flower beds shrubs, and gardens. They may be droughty and require frequent watering for plant growth. The soil cracks when dry, swells when wet. Clayey soils often have a high shrink-swell potential. Special planning and design are required for foundations.

Loamy (medium): None to slight limitations - care should be exercised during construction to be sure the surface soil is not covered by less desirable material. Shrink-swell is moderate or low. It is easy to excavate and absorbs wastewater well.

Sandy (coarse): Moderate limitations - may require stabilization with organic material and/or loamy topsoil to improve moisture and nutrient holding capacity for desired plant growth. Washing and blowing may be a problem during construction. Shrink-swell potential is low. It is easy to excavate and absorbs wastewater well.

Permeability - This normally refers to the rate of water or air movement through the most restrictive layer in the soil. Laterals for septic systems may be located below such layers in some soils. Restrictive layers should serve as a warning and final design should be based on the standard post hole method of determining infiltration where soils are slow or very slowly permeable. It is an important factor when deciding between a septic tank system or a sewage lagoon. Soil percolation tests would be required before making further plans. Special note: For septic systems, consider the permeability below 30 inches.

Very Slow Permeability - causes very severe limitations for septic systems. Water movement is generally less than 0.06" per hour. This would require a prohibitively large field of laterals or costly modifications would be necessary. Septic systems are generally not recommended. This condition causes none to slight limitations for lagoons or other community sewage systems. Subsoils generally are of clayey texture and break into sharp angular chunks 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. Shrink-swell potential is generally high. Very slow permeability causes severe limitations for foundations and basement construction, and for lawns and gardens.

Slow Permeability - causes severe limitations for septic tank systems. Texture is generally on the fine side of the loamy group such as silty clay loams to heavy clay loams with blocky to crumbly structure. Problems are generally similar to the very slowly permeable soils but the modifications required for use are not as great. Water movement can range from 0.06 to 0.60 inches per hour, the cost of modification or size of field necessary would generally be prohibitive. Other limitations would be none to slight for sewage lagoons and moderate for basements, foundations and lawns and gardens.

Moderate Permeability - causes slight to moderate limitations. Textures are generally light silty clay loams, light clay loams, light sandy clay loams, and other loams with no severe restrictive layers, and with columnar to granular or soft blocky structure. Permeability ranges are 0.60" to 2" per hour. This condition also produces moderate limitations for sewage lagoons and none to slight limitations for all other uses.

Rapid Permeability - causes slight limitations for foundations and basement construction, moderate limitations for lawns and gardens, and very severe limitations for septic systems and sewage lagoons. Textures are generally sandy loams or sand throughout. Permeability is greater than 2.0" per hour. Septic systems may not adequately filter effluent under rapidly permeable conditions that would create a very severe limitation. If subsoil texture is sandy, permeability is probably greater than 6.0" per hour. Seepage from lagoons would make it difficult to maintain adequate depth of water and could contribute to pollution of ground water.

Soil Depth - This refers to the vertical depth of a soil to bedrock such as sandstone, limestone, shale that restrict roots and prohibit excavations. Severity of limitations, because of depth, vary greatly for different uses, therefore, Table I is to be used as a guide for evaluation of soil depth for alternate uses.

Table I: Homesite Use Limitations by Soil Depth Classes

*Moderate limitation for bedrock rippable with a backhoe to more than 72".

Slope - This refers to the vertical rise or fall over 100 feet of distance expressed in percent. In West Virginia, the slope ranges for homesite evaluation are the same as those for agricultural land judging. Each mapped soil unit will have a certain slope range. Table II will aid in interpretation of the slope condition actually found. Slope stakes are placed 50 feet apart in West Virginia.

Table II: Homesite Limitation by Slope Classes

Erosion - This depends on internal soil properties, degree of slope, and rate of surface runoff. Anything that protects the soil surface from exposure to rainfall impact and from uninhibited surface water runoff will reduce soil erosion and sediment loss into natural water courses and reservoirs. Unlike natural and farmed lands with vegetative cover, construction sites are drastic man-made soil disturbances which deplete the future homesite of valuable topsoil and may create intolerable stream pollution and flooding problems in downstream communities. Since most erosion is gradual surface removal of soil particles, it can be judged by looking at the thickness of the original dark topsoil. Because exposed soil tends to be very prone to erosion (especially subsoil), the classification of erosion hazard in relation to slope should be applied to the condition of the building site while construction is in progress or to the established homesite. The definition of the classes is the same as that for agricultural land judging.

None-Slight Erosion: Less than 25% of the topsoil has been removed. None to slight limitations for any use.

Moderate Erosion: 25% to 75% of the topsoil has been removed. Slight limitations for all uses.

Severe Erosion: More than 75% of the topsoil has been removed; small gullies may be present. Moderate limitations for all uses, except severe for lawns and gardens.

Very Severe Erosion: All the topsoil and some subsoil has been removed. Severe limitations for all uses. Deep furrows and gullies may be present. This condition will require extensive filling and leveling, extra cost for septic systems, extensive modifications for landscaping, etc. Erosion control measures should be carried out during construction

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 on to planed or established homesites and the possibility of ponding and water accumulation around the homesite need consideration. Surface runoff is not a factor for sewage lagoons because they will be protected from outside water by a dike or berm.

Rapid Runoff: Occurs on slopes of 8% or more. Severe limitations require care to maintain and to prevent erosion on lawns and gardens. None to slight limitations for foundations with basements or septic systems.

Moderate runoff- None to slight limitations for any use. Occurs on slopes of more than 1 to less than 8%.

Slow runoff - Occurs on nearly level areas (0 to 1% slope). Severe limitations for foundation with basements and for septic tank disposal fields. None to slight limitations for other uses.

Very Slow runoff - Occurs on level land (0 to 1% slope) where water accumulates in depressional areas and has no surface outlet. Very severe limitations for foundations with basements and for septic systems. None to slight limitations for other uses.

Shrink-Swell of Subsoil (or finest textured soil layer) is a property of the clay fraction in soils. Many clays swell when they absorb water and shrink when they dry. This characteristic is most noticeable in the subsoil where the finest textured layers of the soil profile are usually found. The red clays of the central and western counties in West Virginia have a particularly high shrink-swell potential, swelling to over twice their dry volume and causing very severe land use limitations. They tend to be unstable and prone to erosion and downhill slides on sloping sites. Swelling pressure of such clays may cause damage to foundations and retaining walls, while soil drainage and permeability are limited. There is a close correlation between soil texture, shrink-swell potential and soil permeability. Keep in mind, however, that not all clays (fine textured soils) demonstrate equal shrink-swell.

Low Shrink-Swell - Occurs in subsoils that have coarse texture (sands, loamy sands and sandy loams), and the permeability is rapid. None to slight limitations for all uses.

Moderate Shrink-Swell - Occurs in subsoils that have moderate texture (loams, sandy clay loams, silt loams, silts, silty clay loams, and clay loams), and the permeability is moderate or slow. Moderate limitations for all uses.

High Shrink-Swell - Occurs in subsoils that have fine or clayey texture (sandy clay, silty clay and clay), and the permeability is very slow. Severe limitations for foundations, septic systems and other uses, except none to slight limitations 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. For example, a very slowly permeable soil normally exhibits poor to very poor internal drainage. The presence and depth of a water table is not necessarily a reflection of soil permeability. It must be evaluated on the basis of both depth and permanence, frequently requiring study during different seasons of the year. Unless obvious, water table depth information will be provided in a contest.

Deep: The temporary or permanent water table is present at depths more than 72". None to slight limitations for all uses.

Moderate: The temporary or permanent water table is present at depths of 48" to 72". Moderate limitations for all uses.

Shallow: Temporary or permanent water table is present at depths less than  48". Severe limitations for all uses.

Flooding: The occurrence of floods is a factor frequently overlooked. Flooding may not occur on an area for many years, then a serious flood can occur. Urban development in a watershed may increase runoff up to 70% in streams, thus greatly increasing flood hazards. Soils can give an indication, but records must be studied to determine the true condition. Position in the landscape and proximity to nearby streams are good indicators of frequency of flooding. In contests this is normally given information.

No Flooding: None to slight limitations for all uses. Frequency of flooding is less than one in four years.

Occasional Flooding: Floods one or two years in four. Severe limitations for housing, septic field and sewage lagoons; moderate limitations for lawns and gardens.

Frequent Flooding: Floods more than two years in four. Very severe limitations for all uses.

Final Evaluation

In making the final evaluation of the homesite in a contest, you must determine the degree of limitation for each site factor as it applies to the planned use. For example, under septic system, if one or more factors are marked severe, but none very severe, then in the final evaluation the limitation for septic system would be marked severe.

When you are considering the purchase of an existing home or of a site for home construction, you are urged to study the soil map of the site, make on-site examinations and seek the assistance of the Natural Resources Conservation Service or specialists of the WVU Extension Service before making the final decision. If a septic tank system or similar on-site wastewater disposal system is needed, you must have the County Health Department Sanitarian check a soil percolation test and issue a permit before construction is started. If soil maps or reports are not available for that area, contact your local Natural Resources Conservation District Office for information. Many areas have been mapped even though the maps and reports may not have been published. Careful consideration of the factors discussed herein may not answer all of the problems encountered by the prospective homeowner or builder, but many costly mistakes can be prevented by careful advance study and by seeking the advice of soil scientists.

Land Judging for Farms and Homesites (2004) was prepared by Dr. Jeff Skousen, 1106 Agricultural Sciences, West Virginia University, Morgantown, WV 26506-6108.

The 2004 Land Judging Manual was developed from land judging materials and booklets prepared by George Sharpe and Richard Zimmerman. The success and popularity of the land judging program in West Virginia can be attributed to the leadership of George Sharpe and Richard Zimmerman, and the continuing efforts of many dedicated Vo-Ag teachers and extension agents throughout the state.

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