If you’re considering major plant modifications now or in the future, you need to understand how heavy industrial equipment foundations are designed and constructed. Below we discuss what to expect during this process, the unique challenges and considerations owners face, and how to avoid pitfalls.
1. Design Considerations
Soil Conditions
Your design process should set you up for success in future phases of work. A good design engineer will have soil borings and a geotechnical report done. These will test to make sure that soil properties such as the bearing pressure, cohesiveness of the soil, water table, and any soil contaminants are well understood.
Current Building Conditions
Next, examine your current building conditions including the location and depth of existing interior foundations, exterior perimeter foundations, crane runway foundations and bracing, the height of the building, and the location of utilities. It helps to have good original drawings and drawings of any subsequent projects completed in the proximity of the new equipment.
Equipment Loads
The designer will use manufacturer information to make sure the foundation is designed to support all possible equipment load scenarios. These include static and dynamic loads, and any other factors that would impact the total load (i.e., nearby equipment, overhead crane loads, etc.).
Concrete Geometry
The foundation will be designed based on the exact geometrical dimensions needed to fit the equipment onto or into the foundation, usually provided by the manufacturer. The scrap system, feed system, and exit handling will also impact these requirements and need to be taken into consideration.
Pit Requirements
The pit requirements, its width, length, and depth, will mainly depend on the equipment and type of material processed. Once depth is determined, the soils, water, and depth of bedrock will need to be examined to determine the load capacity of the soils relative to your foundation size. Also, any and what type of waterproofing system is required (such as integral concrete waterproofing, waterstop at joints, or an exterior membrane system) is considered at this point.
Controls and Piping Raceways
How power is fed to the equipment, other controls, and any hydraulic piping raceways must be part of the foundation design. Additionally, certain items must be embedded in the foundation, such as equipment bearing items (steel frames, beams, etc.), rails, anchor bolts, isolators, or other items required by the owner or manufacturer. It’s essential that all of these are incorporated during the design phase of your project.
2. Construction Considerations & Techniques
Project Schedule
After the design phase is complete, construction can begin. First, a project schedule will be determined, which is often contingent upon the new (or used) equipment delivery date. Shutdowns, holidays, seasonal considerations, lead time for construction materials (such as specialty construction equipment, embedded steel, and rebar), and even the water table level will impact the project timeline.
Safety
After the design phase is complete, construction can begin. First, a project schedule will be determined, which is often contingent upon the new (or used) equipment delivery date. Shutdowns, holidays, seasonal considerations, lead time for construction materials (such as specialty construction equipment, embedded steel, and rebar), and even the water table level will impact the project timeline.
Work Access
Construction crews’ access to the work area will affect how quickly work can get done. Crews will require adequate overhead door, aisleway, loading dock, and at-grade access and will need to consider the proximity of existing active equipment and production lines, including access to existing overhead cranes. Crews will work around and within the existing building foundations, overhead clearance, and underground utilities.
Excavating, Earth Retention, and De-watering
During construction, the earth retention system, de-watering techniques, and excavation techniques used to build the pit will affect your overall cost and project timeline. Steel sheeting and soldier pile and lagging are earth retention systems that each have their own application depending on soil conditions. They come with their own separate costs and are dictated by multiple factors. Well points or sumps can be used to de-water the pit if needed. Various excavation techniques will also impact the final result and cost of the project.
Quality Control
Finally, quality control measures must be taken such as onsite in-place soil bearing capacity testing, concrete testing, construction documentation, and adequate photo/video documentation, to prevent avoidable call-backs after the job is completed. Reputable contractors are known for their quality of construction based on previously successfully completed projects.
3. Economic Drivers
There are several key items that can significantly affect the total cost of your new foundation. Making smart decisions regarding these items will ensure the greatest return on your investment.
Size, Depth, and Soil Condition of Pit
The size and depth of the main pit itself, in addition to the soils conditions and water table, are key components that will drive total cost. The earth retention system used and the need for a dewatering system while constructing the pit will also impact cost.
Auxiliary Pits, Concrete Geometry, and Work Access
Other items that might increase costs include the number of auxiliary pits required, such as scrap conveyor or product handling pits, embedded steel items, the concrete geometry including elevation changes, necessary troughs and pockets, the amount of overhead building height, and access to use the owner’s overhead cranes during construction.
Choosing the Right Contractor
Finally, selecting the right designer/contractor can have the biggest impact on the cost of your project. There are many designers and contractors, but not all have experience designing and/or constructing foundations for heavy industrial equipment. Your selected designer/contractor should be able to anticipate problems, suggest practical solutions for your unique situation, and do so with economics in mind. Be aware that the lowest-price designer/contractor may not always be the best choice. The reduced lifecycle cost from poor quality and/or poorly designed foundations will far outweigh the cost of designing and constructing it correctly the first time. There also is a cost to meeting challenging construction schedules such as overtime, worker inefficiencies, and fast-tracking material lead times.
Trade-Offs
There are always trade-offs when it comes to industrial equipment and their foundations. Typically, the more automation you have (or are planning to use) in your production, the greater the construction costs will be in all areas mentioned here, but the larger the return on investment.
Conclusion
Deciding to invest in your plant to better serve your customers, become more efficient, and make you more competitive in the marketplace is a major decision, and there is much at stake. Therefore, it’s important to have a decent understanding of the design and construction process for equipment foundations and which of its components can most greatly impact total cost. A trustworthy and experienced design/construction partner can be invaluable in leading you through this process.
*A version of this article appeared in The Fabricator in June 2022.