What are foundation and soil conditions in ZIP code 73121 (near Del City)?

Reviewed by Preston · Updated 2026-11-12

In short: ZIP code 73121 has a mix of ground: about 14% high shrink-swell soil, 10% moderate and 54% low ¹. The soil survey also maps bedrock within 40 inches under about 34% ¹.

What does the soil survey show for 73121?

ZIP code 73121 covers about 10 square miles of land and had 3,218 people in the 2020 Census ²; its center is outside city limits, nearest Del City.

Which soils matter most for houses in 73121?

• Stephenville, about 15% of the area ¹: Moderately deep, well drained, soils formed in material weathered from sandstone of Permian age ³.
• Harrah, about 14% of the area ¹: Soils that are very deep to sandstone bedrock, well drained soils that formed in sandy and loamy colluvium weathered from sandstone of Permian age ⁴.
• Teller, about 10% of the area ¹: Very deep, well drained, moderately permeable soils that formed in loamy sediments of Pleistocene age ⁵.
• Darnell, about 9% of the area ¹: Shallow, well drained to somewhat excessively drained soils formed in material weathered from sandstone of Permian age ⁶.
• Renthin, about 6% of the area ¹: Deep, well drained, very slowly permeable soils formed in material weathered from clayey and silty shale of Permian age ⁷.
• Urban land, about 10%, is ground the survey maps as covered by buildings and pavement rather than classifying its soil ¹.

What does this mean for houses in 73121?

Shallow rock. Where bedrock is close to the surface, lots are often cut into rock on one side and built up with fill on the other, so fill settlement and slope creep matter more than clay swell, and piers can stop at very different depths across one house. See depth to rock from borings.

Flood-prone soils. Floodplain soils are layered stream deposits: softer, wetter and more variable than upland soils, and they flood. See soft soil consolidation and Quaternary alluvium and terraces.

Which soils cover 73121?

Looking for a foundation company near ZIP code 73121?

Companies that serve ZIP code 73121 can appear on the company map in the Homeowner Hub. Paid listings there are marked Sponsored; the library and the AI guide don't rank or recommend any of them.

Buying or selling a house in ZIP code 73121? Realtors who serve the area can be on the same map, also marked Sponsored, and for realtors covers the seller disclosure form, inspections and the sale timeline. Seeing cracks at home? Start with for homeowners.

How were these numbers measured?

We overlaid the ZIP code tabulation area (the Census approximation of a ZIP code) from the Census Bureau ² on the USDA soil survey's map units ¹ and added up the area of each soil. Where a map unit is a mix of soils, its area was split by the percentages the survey lists for its major soils, so shares leave out minor inclusions and do not add to 100%. Shrink-swell is rated by the linear extensibility of a soil's most expansive layer, the survey's measure of how much it changes length between wet and dry (6% or more is high). Water table, bedrock and flooding come from the survey's map-unit summaries: the shallowest water table in any month, the shallowest bedrock, and the most common flooding frequency. Bedrock here includes soft, weathered sandstone and shale that a pier can push through, so it is not the depth where piers stop. These are mapped averages, not a test of any one lot; fill, grading and the soil actually under a house can differ, which is why a site visit or soil boring still decides a repair.

Related

• Del City
• Oklahoma City metro
• ZIP code 73111
• ZIP code 73141
• ZIP code 73117
• ZIP code 73105
• Shrink-swell and the active zone