Yes, a geotechnical report is essential for determining the precise depth and design of helical piers. According to the provided content, this report provides the technical data needed to establish where stable load-bearing soil begins.

A geotechnical report helps determine pier depth through several key components:

• Soil Stratigraphy Logs: These logs identify distinct soil layers and their density (measured as N-values), which allow engineers to calculate the exact depth required to reach a competent bearing stratum, such as dense sand or bedrock.
• Frost Depth: In Colorado’s climate, the report establishes the minimum embedment depth needed to place piers below the frost line to prevent frost heave.
• Soil Composition: The report identifies expansive soils (like clay) that may require deeper pier installation to bypass active soil zones that shrink and swell.
• Bearing Capacity: By calculating the soil’s ability to support loads, the report dictates the depth and configuration (number and size of helices) necessary for structural stability.

Unlike a simple perc test, which only measures water absorption, a geotechnical report provides the laboratory-analyzed data required by building codes and engineering standards (such as ICC-ES AC358) to verify pier capacity and installation depth.