What is Richfield soil and how does it affect Oklahoma foundations?

Reviewed by Preston, Oklahoma foundation repair consultant · Updated 2026-10-14

In short: Richfield is a deep, well-drained soil formed in thick windblown silt (loess) on the flat tablelands of the Oklahoma Panhandle and nearby high plains. Its subsoil is a smectitic silty clay loam with 35 to 42 percent clay, the type of clay associated with shrink-swell. Because it formed in loess in a dry climate, both clay movement and collapse on wetting are topics for foundations.

What is Richfield soil?

Richfield is an official USDA soil series classified as "Fine, smectitic, mesic Aridic Argiustolls" ¹. "Smectitic" refers to its clay mineralogy ¹. It formed in calcareous loess 1 meter (about 3 feet) to more than 3 meters (about 10 feet) thick ¹.

The soil occurs on tablelands, mostly plane, with slopes of 0 to 6 percent at elevations of 2,600 to 4,600 feet ¹. It is mapped in western Kansas and Nebraska, eastern Colorado, southwestern South Dakota and the Oklahoma Panhandle, and is of large extent ¹. The type location is in Grant County, Kansas ¹. Mean annual precipitation is about 18 inches (range 13-22) ¹. Most areas are cultivated to winter wheat and sorghum ¹.

In Oklahoma, this places Richfield in the Panhandle (High Plains), on the Ogallala Formation and loess.

What does a Richfield soil profile look like?

Source for the table: ¹. Other properties from the official description ¹:

• Drainage: well drained; saturated hydraulic conductivity moderately high ¹.
• Carbonates: secondary calcium carbonate at 10 to 24 inches ¹.
• Classification note: lab data place it near the boundary of fine and fine-silty families ¹.
• Water table and cracks: not described ¹.

What does Richfield soil mean for foundations?

Smectitic clay in the subsoil

A federal survey of expansive materials noted that montmorillonite, a smectite clay, contributes to the widespread occurrence of expansive materials, notably in the Great Plains ³. Richfield's subsoil is smectitic with 35 to 42 percent clay ¹. Clayey soils heave as they gain water and settle as they dry, and uneven moisture change around a shallow foundation is what causes damaging movement ⁵.

The USDA rates shrink-swell as linear extensibility: 3 to 6 percent moderate, 6 to 9 percent high, 9 percent or more very high ⁶. The rated value for each mapped unit is in Web Soil Survey ². Patterns to read about:

• Perimeter drying settlement (edge drop)
• Perimeter wetting heave (edge lift)
• Tree-root desiccation settlement

Loess and collapse

Collapsible soils are unsaturated soils that rearrange and lose volume when wetted ⁴. Engineering guidance lists windblown deposits such as loess among the natural sources of collapsible soil, and notes these deposits are common in arid and semi-arid climates ⁴. Collapse does not require full saturation ⁴. Richfield formed in loess in a climate with about 18 inches of annual precipitation ¹, though its official description does not report collapse.

Collapse potential is evaluated with index tests and oedometer testing under ASTM D4546, and the guidance recommends weighing both ⁴. See collapsible and loess soils and hydrocollapse.

Water around the house

Shrink-swell movement and collapse are both driven by changes in soil moisture ⁴⁵. The ASCE Geo-Institute guide recommends discharging downspouts at least 3 feet from the foundation, keeping irrigation at least 5 feet away and repairing plumbing leaks ⁵. See surface drainage and grading and plumbing leaks under slab.

Related

• Ulysses soil
• Dalhart soil
• Freeze-thaw and frost depth
• Clay mineralogy
• Soil series index