What are the organic content limits for determining organic materials?

• A. An average content of 5% or greater or an individual content of 7% or greater
• B. An average content of 3% or greater or an individual content of 8% or greater
• C. An average content of 2% or greater or an individual content of 5% or greater
• D. Organic content is not used in determinations

Answer: (A)

The main idea here is how organic material in soil is evaluated to decide if the material can be used for earthwork. Organic matter weakens soil—it can reduce strength, increase compressibility, and cause settlement issues—so we use specific limits to identify when soil is considered organic.

The rule uses two checks: if the average organic content across samples is five percent or more, the material is classified as organic. Even if the average is below that, any single sample showing seven percent or more organic content also flags the material as organic because localized pockets can still cause problems. When soil is classified as organic, it usually needs to be removed or stabilized before it can be used as fill or subgrade.

The other options don’t fit because they use different thresholds or suggest organic content isn’t used at all, which conflicts with the practice of identifying organic soils to ensure safe, stable earthwork.