At GeoCiv, we understand that every site presents unique geotechnical challenges. Our team provides comprehensive soil testing, compaction testing, and geotechnical services that meet project-specific requirements and help builders, developers, owners and contractors achieve success in Alabama.
What Are the Requirements in Alabama?
For any project falling under the Alabama Building Code (IBC) such as commercial structures, large multi-family buildings, or state-funded projects, building departments take a thorough, document-driven approach.
If a site has a foundation relying on fill dirt, building officials in every major city (e.g. Birmingham, Huntsville, Guntersville, Montgomery, Tuscaloosa, Gadsden, Mobile) will not issue specific permits until a sealed report from a licensed Alabama professional engineer (P.E.) is submitted.
Enforcing the 12-Inch Exception: If a contractor claims they do not need a geotechnical report because they have “less than 12 inches of fill” (invoking IBC 1804.6), local inspectors will require a compaction report from a third-party testing agency verifying that the fill achieved at least 90% maximum dry density as required by IBC 1804.6.
For one- and two-family dwellings up to three stories, the IRC codes apply. If a residential foundation is going to rest on fill soil, the IRC mandates that the soil must be designed, installed, and tested in accordance with “accepted engineering practice”.
What this means in practice: Because the IRC does not provide a baseline number, the local building official or a hired geotechnical engineer determines what constitutes “accepted engineering practice”. In almost all jurisdictions, this translates to requiring the fill to be placed in 6-to-8-inch lifts and compacted to at least 95% maximum dry density (MDD) per ASTM D1557 or ASTM D698, verified by field density testing.
For a typical crawlspace foundation with formed or trenched footings, the natural, undisturbed soil at the bottom of the footings is evaluated using in-situ or penetrometer testing to directly verify the subgrade strength before the building department allows the concrete pour to proceed.
The outcome of proper construction specifications and testing is a suitable subgrade or an Engineered fill soil that will provide a solid base to support buildings, roads, retaining walls, embankments, and other infrastructure. Your project may experience extreme settlement, foundation movement, pavement failure, or expensive repairs when an unsuitable subgrade or uncontrolled fill is used.
What Is Engineered Fill Soil?
Engineered fill soil is designed to meet specific engineering requirements unlike ordinary fill or uncontrolled backfill. Engineered fill is installed under controlled conditions to achieve predictable strength, stability, drainage, and load-bearing performance.
GeoCiv will conduct laboratory proctor testing to verify that it is suitable for fill material and to determine the characteristics and compaction properties. During construction, field testing will verify that density and moisture levels are obtained.
Engineered fill is commonly used for:
- Building foundations
- Roadways and highways
- Bridge approaches
- Retaining wall backfill
- Structural pads
- Parking lots
- Developments
- Embankments
- Utility trenches
Why Engineered Fill Soil Is Critical for Construction
Throughout Alabama, certain sites contain soils that are unsuitable for structures due to:
- Loose sands
- Expansive clays
- Compressible silts
- Organic materials
- Uncontrolled fill
Reduces Settlement
Settlement occurs when soil compresses under structural loads. Settlement may lead to:
- Foundation cracking
- Uneven floors
- Misaligned doors and windows
- Pavement distress
- Utility damage
Characteristics of Engineered Fill Soil
Not every soil is suitable for engineered fill applications. GeoCiv will evaluate the potential fill material to ensure it is suitable and meets project specifications.
Engineered Fill Construction Procedures
1. Site Investigation
Before any earthwork begins, GeoCiv evaluates:
- Existing soil conditions
- On-site borrow areas
- Fill material sourced off-site
- Groundwater levels
- Settlement potential
- Foundation requirements
2. Material Selection
GeoCiv determines whether native soils are suitable or if imported fill is required.
Laboratory testing evaluates:
- Grain size distribution
- Plasticity
- Moisture-density relationships
- Expansion potential
- Strength characteristics
3. Site Preparation
Proper preparation includes:
- Removing unsuitable soils
- Clearing vegetation
- Excavating soft areas
- Establishing drainage
- Preparing the subgrade surface
4. Fill Placement
Engineered fill is installed in lifts and tested. This approach allows each layer to achieve the specified density and provides a uniform foundation.
5. Soil Compaction and Testing
Compaction is a critical step in the process and should be conducted with specific equipment depending on the type of fill material. Field density testing and proctor testing will be conducted by GeoCiv according to:
- Standard Proctor Test (ASTM D698)
- Modified Proctor Test (ASTM D1557)
Why Choose GeoCiv?
Selecting the right geotechnical consultant is essential for successful earthwork and foundation construction.
GeoCiv provides complete services that include:
- Soil testing
- Geotechnical investigations
- Compaction testing
- Construction observation
- Recommendations for Earthwork
- Foundation support recommendations
Conclusion
Successful construction starts with a solid foundation. A geotechnical evaluation with soils and compaction testing is one of the most effective ways to support long-term stability. Call us today and let us walk you through the soils testing process. 256-601-7228
GeoCiv, Building Trust. Engineering Partnerships.
