SW-Funk contractor excavating a deep foundation

Proper foundation excavation is vital for the stability and longevity of any structure. A well-excavated foundation ensures that the building can withstand the test of time and the forces of nature. 

This guide provides insights into foundation excavation, providing expert insights and best practices to help you achieve the best results.


Types of Foundations

Before starting the excavation process, it’s essential to understand the different types of foundations:

Shallow Foundations

Shallow Foundations are suitable for smaller structures with lighter loads and stable soil conditions. Examples include slab-on-grade and spread footings.

Deep Foundations

Deep Foundations are necessary for larger structures, heavy loads or poor soil conditions. Deep foundations transfer the load to more stable soil or bedrock. Common types include:

  • Piles: Driven deep into the ground to provide support
  • Caissons: Drilled shafts filled with concrete
  • Drilled shafts: Similar to caissons but typically larger in diameter

Foundation Soles

Regardless of the type of foundation, a foundation sole is a necessary component. Foundation soles, or footings, are essential to the foundation system

They provide a base for stem walls and evenly distribute the structure’s load, providing additional stability and ensuring a firm foundation for the building. They are typically wider than the foundation wall or column they support, spreading the load over a larger area to reduce soil pressure. 

Structural engineers consider factors such as soil-bearing capacity, building weight, and local building codes to determine the appropriate size and depth of the soles. Additional measures, such as soil reinforcement or deeper excavation, may be necessary if the soil’s bearing capacity is inadequate.

It is important to carefully excavate the soles to the required depth, ensuring a level and stable base. The excavation for foundation soles should be clean, with loose soil and debris removed to create a firm, undisturbed surface for placing concrete.

Properly designed and constructed foundation soles help prevent differential settlement, minimize the risk of foundation failure and ensure the structure’s long-term performance.


Site Preparation

Yellow and black excavator on brown soil

Source: Unsplash

Before excavation can begin, proper site preparation is essential:

  • Obtain Necessary Permits: Check with local authorities to ensure you have all required permits for the excavation work.
  • Locate and Mark Utilities: Contact utility companies to locate and mark underground utilities, such as gas lines, water mains and electrical cables.
  • Clear and Grub the Site: Remove any vegetation, debris or existing structures that may interfere with excavation.

Soil Management

Proper soil management throughout the entire area is essential for a successful excavation because the soil conditions directly impact the foundation’s stability and the structure’s long-term performance

Poor soil conditions, such as loose, compressible or expansive soils, can lead to foundation settlement, cracking or failure. Additionally, groundwater can weaken the soil’s bearing capacity and cause erosion, undermining the foundation’s stability.

Consider these best practices:

  • Identify Soil Types: Understand the soil characteristics on your site, such as its bearing capacity and drainage properties.
  • Deal with Groundwater: If groundwater is present, use dewatering techniques such as pumps or drainage systems to remove it.
  • Stabilize the Soil: If necessary, use soil stabilization methods such as grouting or mixing to improve the soil’s bearing capacity.

Properly identifying and managing the soil conditions, using the OSHA classification outline, is important for ensuring you construct the foundation on stable, well-draining soil that can support the structure’s load. 

This may involve using specialized techniques, such as soil stabilization or dewatering, to improve the soil’s properties and create a suitable foundation base. 

Investing time and resources in effective soil management during the excavation phase can help prevent costly issues and ensure the long-term success of your construction project.


Excavation Equipment

A bulldozer and large work truck move across a worksite

Having the right equipment is crucial for efficient and safe foundation excavation. The most common excavation equipment includes:

  • Excavators: Excavators are versatile machines that can dig, lift and move soil and debris. They are ideal for larger excavation projects and can handle various tasks.
  • Backhoes: Smaller than excavators, backhoes are perfect for digging trenches and holes in tighter spaces. They offer more precision and maneuverability than larger equipment.
  • Bulldozers: Used for grading and leveling the site, bulldozers are powerful machines that can efficiently move large amounts of soil and debris.
  • Skid Steers: Compact and maneuverable, skid steers are excellent for working in tight spaces and handling smaller tasks, such as moving materials or backfilling.

Always wear appropriate personal protective equipment (PPE) such as hard hats, safety glasses and steel-toed boots when operating excavation equipment to ensure worker safety.

Step-by-Step Excavation Process

The foundation excavation process itself involves several key steps:

Set out the Foundation Layout

Use surveying equipment to accurately mark the foundation’s boundaries and elevations, ensuring proper placement within the lot layout.

Determine the Excavation Depth

Consult the foundation design to determine the required excavation depth.

Excavate in Layers

Remove soil in layers, ensuring each layer is level and stable before proceeding. Use the appropriate equipment, such as excavators and backhoes, to remove soil and debris efficiently.

Maintain Proper Slopes and Benching

Follow OSHA guidelines for sloping and benching to prevent cave-ins and ensure worker safety. Benching involves creating horizontal levels or steps while sloping means cutting back the trench wall at an inclined angle. Benching is not suitable for Type C soil.

Undercut for Foundation Soles

Excavate additional depth for foundation soles, which provide extra support and stability.

Level and Grade the Site

Use bulldozers and skid steers to level and grade the excavated area as needed, creating a smooth and even surface for the foundation construction.

Using the right equipment and following these steps ensures you complete your foundation excavation safely, efficiently and to the highest standards. 

Remember to work with experienced professionals who understand the intricacies of the excavation process and can guide you through each step, from site preparation to backfilling and compaction.


Quality Control, Inspections and Safety Considerations

Ensuring the highest workmanship, safety and compliance standards is essential for a successful foundation excavation project. To achieve these goals, implement a comprehensive quality control plan that includes:

  • Regular inspections by qualified professionals during the excavation process and before concrete placement
  • Identification of potential hazards such as underground utilities, unstable soil or heavy equipment, and appropriate measures to mitigate risks
  • A comprehensive safety program that includes training, hazard communication and regular safety meetings
  • Proper use of personal protective equipment (PPE) such as hard hats, safety glasses and steel-toed boots by all workers

Prioritizing safety measures and working with a reputable, experienced construction company is the best way to ensure that your foundation excavation is completed to the highest standards while minimizing the risk of accidents or injuries.


Environmental Impact and Sustainable Practices

Excavation projects can have significant impacts on the surrounding environment. It’s essential to identify and address potential environmental concerns to minimize negative effects and ensure compliance with regulations. 

Soil erosion

Excavation is likely to affect the soil, reducing its stability, and surface runoff of sediments. Prevent soil erosion and protect surrounding water bodies by erecting silt fences, erosion blankets, and sediment traps.

Soils contamination

The soil on some sites might be contaminated with hazardous materials such as chemicals and heavy metals. Test the soil deeply before the excavation, and if polluted, ensure you address the problem. If the tests reveal any contamination cover, transport, and dispose of the soil properly to avoid polluting the environment.

Groundwater Protection

Disturbance of natural underground water flow systems can lead to potential pollution. Dewatering systems to lower the groundwater levels and prevent infiltration of potentially contaminated rainwater is recommended.

Noise and Air Quality

Toxic fumes in the air and noise that affects residents nearby are also possible environmental harm. Dust control using water or a dust suppressant to contain dust at the excavation site, informed measures of using equipment during non-working hours to increase overall productivity and to limit emission levels. 

Waste Management

Proper handling of concentrated excavation materials such as soil, debris, and construction materials. Classified under the best possible recycling/disposal classification per local bulking and sources studied. Analyze if it is possible to identify streams and introduce the waste to a recycling resource.


Your Trusted Partner for Safe and Reliable Foundation Excavation

SW Funk Industrial Contractors has been a leader in industrial construction since 1980, specializing in concrete and structural steel projects. Our commitment to safety and experienced team ensure that your foundation excavation project is completed safely, accurately and on time, even in the most challenging environments.

Our concrete capabilities are second to none. Our skilled contractors specialize in complex installations and repairs, from large foundations to intricate anchor bolt layouts. We also excel in structural steel, offering a full range of services to meet your needs.

Whether you need excavation, demolition, foundation construction or repairs, SW Funk Industrial Contractors is your partner in success. Contact us today to learn how we can help you achieve your goals while prioritizing safety and quality.


Frequently Asked Questions

What is the purpose of foundation excavation?

Foundation excavation prepares the site for a structure’s foundation by removing soil to the necessary depth, ensuring a stable base and proper drainage.

How deep should a foundation be excavated?

Excavation depth depends on soil conditions, frost depth and local building codes. Consult a qualified geotechnical engineer or foundation contractor for the right depth for your project.

What is the importance of soil management during excavation?

Soil management is vital because different soil types have varying properties that affect the foundation’s stability. Proper management ensures the foundation is built on stable, well-draining soil.