While property owners often confuse the two, a Perc Test and a Geotechnical Report serve entirely different purposes and cannot be used interchangeably for structural work.
### Perc Test (Percolation Test)
- Primary Purpose: Used solely for septic system design.
- Key Data: It measures the soil’s absorption rate in minutes per inch to determine the size of a leach field.
- Structural Relevance: It provides no data on whether soil can support a building. Building departments will not accept a perc test for foundation permits.
- Typical Cost: $100 – $300 per test hole.
### Geotechnical Report
- Primary Purpose: Evaluates soil bearing capacity for structural foundation design and repair.
- Key Data: Provides comprehensive technical details including soil type classification, density, groundwater depth, shear strength, and shrink/swell potential.
- Structural Relevance: Essential for calculating foundation dimensions and determining the depth and spacing of helical piers.
- Typical Cost: $800 – $3,500 depending on the project scope and site access.
In the Denver metro area, geotechnical reports must be prepared by a licensed geotechnical engineer and follow ASTM standards to ensure the long-term stability of the structure.
Related FAQs
-
How does Torque Monitoring During Installation Verify Helical Pier Load Capacity?
Read More »: How does Torque Monitoring During Installation Verify Helical Pier Load Capacity?Torque monitoring acts as a real-time field verification method to confirm the helical pier load capacity during installation. This process relies on a fundamental engineering relationship where the energy required to drive a pier into the soil correlates directly to…
-
Can Helical Piers Support the Same Load as Traditional Concrete Foundations?
Read More »: Can Helical Piers Support the Same Load as Traditional Concrete Foundations?Yes, helical piers can support structural loads comparable to traditional concrete foundations, though their specific capacities differ based on the application. For typical residential projects, helical pier capacities generally range from 10 to 150 kips (or 50–200 kN) per pier.…
-
What Factors, such as Soil Type and Pier Design, Influence Helical Pier Load Capacity?
Read More »: What Factors, such as Soil Type and Pier Design, Influence Helical Pier Load Capacity?The load capacity of a helical pier is not a fixed number; it is influenced by a combination of environmental conditions, mechanical design, and installation variables. According to the provided content, the primary factors include: Soil Conditions and Groundwater: Soil…
-
How is the Load Capacity of a Helical Pier Determined for a Residential Project?
Read More »: How is the Load Capacity of a Helical Pier Determined for a Residential Project?The load capacity of a helical pier for a residential project is determined through a multi-step process involving geotechnical analysis, engineering calculations, and on-site verification. Key methods used to determine and verify capacity include: Geotechnical Soil Analysis: Engineers evaluate soil…
-
How does the Size of the Structure and its Load Requirements Impact the Final Price per Helical Pile Unit?
Read More »: How does the Size of the Structure and its Load Requirements Impact the Final Price per Helical Pile Unit?The size of a structure and its specific load requirements are primary drivers of the final helical pile price per unit because they dictate the engineering specifications of the piles. Larger or heavier structures require more robust materials and intensive…
