Blog Archives

NFPA 61 & 652: DHA Requirements
1. Ref. 652: pages 1 & 2
2. Ref. 61:
3. Ref. 652:
4. Ref. 654: 4.2.5
5. Ref. 652: 7.1.2
6. Ref. 652: 5.2
7. Ref. 652: 5.1.1
8. Ref. 652: 7.3.1 (2)
9. Ref. 652: 7.1.4
10. Ref. 654:


Next Article: Engineering an Exceptional Pile

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Engineering an Exceptional Pile

Increasing crop yields per acre, inconclusive trade talks and low commodity prices slow the movement of corn and grain, leaving elevator owners to consider how best to add storage capacity while minimizing costs and protecting their product.

Installing a temporary storage system (commonly known as a ground pile) is faster and cheaper than building a steel or concrete bin, but several aspects need to be considered to ensure the best possible outcome.

Ground pile “structure” varies greatly, from ultra-temporary storage directly on the ground to piles sited on a gravel, asphalt or concrete surface. Some piles have no sidewalls, while others include 4' to 8' steel or concrete sidewalls that provide stability and allow grain to be piled higher.

Simply piling grain on the ground may seem like an easy storage solution, but it can end up costing elevator owners money. Soil is likely to mix with the bottom 18 – 24” of grain, resulting in product lost to contamination and rot.

Piles sited on gravel or aglime are better protected, but the bottom 12 – 18” are susceptible to moisture. A concrete surface, if properly constructed, provides the most durable and water-resistant option but it’s comparatively a larger investment. Though it may be cheaper intitially to not install pavement, the loss of product can often pay for these improvements.

Each plant’s storage needs are different and an effective ground pile design will account for a variety of factors, such as an owner’s budget, the amount of grain to be stored and the length of storage time.

Ground piles require a substantial amount of suitable land. Space for drainage, ditching and culverts needs to be factored in to site selection, as well as constraints such as proximity to a county highway right-of-way and / or compliance with local stormwater regulations.

For example, a pile of 1 million – 1.5 million bushels takes up roughly 1.5 – 2 acres (depending on sidewall height); factor in space for the walls, ditching and roadways and the actual footprint of the site is about 4.3 acres.

The topography of the site is also critical, and it’s possible that much earthwork will need to be performed to ensure proper drainage.

The process isn’t overly complicated, but there are some intricacies and factors to be aware of to make a good design. Developing a site grading plan can help minimize drainage issues and make sure the pile can be filled and reclaimed in an efficient manner.

Owners also need to determine how the additional storage impacts other features of the plant, such as relative locations of truck roadways and scales. Understanding how a ground pile fits within the site’s workflow and existing infrastructure ensures the plant continues to operate smoothly.

While year-to-year conditions such as yields, prices and availability of storage space drive the decision to add ground piles, the big question is what the return on investment will be and whether an owner will be able to recoup their costs.

The biggest benefit of ground piles is they provide a less expensive grain storage option than bins because they typically have no real structure. However, the site location, plant layout and how the pile will be filled and reclaimed all impact the project’s return on investment, which is often the ultimate factor in determining whether to add a ground pile.

While elevator owners generally have a good idea of how much grain they want to store and how to go about it efficiently, partnering with an experienced engineer can help owners obtain a cost-effective design tailored to their needs.

A knowledgeable engineer will ask specific questions and offer schematic design as well as big picture planning. 

Taking in to account the site’s typography, plant infrastructure and workflow and owners’ business objectives is essential to creating the most successful storage solution to guard against the loss of product, time and revenue.

About the Author
Landon Pohl, PE
Landon is an Associate / Sr. Civil Engineer with 11 years of experience in designing grading plans, stormwater / site layouts and grain storage and loading facilities for industrial and agribusiness projects. A civil engineering point of contact for one of the Midwest’s well-known Fortune 500 companies specializing in agribusiness, his skill for managing his time and project details is clear in his work, from straight forward site planning and utility coordination to multidiscipline agribusiness and industrial efforts. 


Next Article: Let It Snow! Let It Snow! How about the Loads?

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Let it Snow! Let it Snow! What about the Loads?

Looking out a window after a heavy snowfall, it’s easy to find beauty in a freshly covered landscape – frosted trees in a peaceful blanket of white. Driving across the plains of Minnesota after a snowfall, it’s easy to see the power of nature partially burying fences and roadways as new snow swirls to threatening depths.

As we watch the nightly weather forecast, predicting and pinpointing the intensity and amount of snow can be a challenge. Wind transforms existing and falling snow into massive drifts as it blows, swirls and repositions snow on and around roofs and buildings. This repositioning can result in existing snow landing on the ground or lower roofs, canopies, adjacent buildings and even vehicles parked next to the building such as a semi-trailer backed into a warehouse dock door

Whether snow is angelic or angry, does drifting represent a threat to the buildings and structures you own, occupy and operate? Are codes and engineers “too conservative” in situations where the chance of structural failure seems low? It may not be an everyday occurrence, but when Jack Frost throws a fastball, it is crucial to know your facility or building can withstand the elements.

Structural engineers rely on building codes to provide criteria for their design. Codes tell us how much snow and snowdrift weight a building needs to support. They also offer methods for determining snow loading applied to specific roof configurations. In the United States, ASCE 7: Minimum Design Loads for Buildings and Other Structures is the national code that provides load requirements for general structural design, including snow loads. For our neighbors to the north, The National Building Code of Canada sets the loading requirements for designing structures.

Historical data documenting snow load totals, snowfall intensity, moisture content, wind speed and wind direction are the basis for ASCE 7.  In mountainous areas and near major lakes and oceans, detailed local maps may be available to highlight county-by-county variations in potential snowfall amounts. Building codes, with their primary focus on public safety, will continue to evolve as more and better data is available and as climatic conditions change.

Building dimensions are significant because the length, or fetch, of a roof is the primary source of the snow that accumulates into windward and leeward drifts on buildings with multiple roof levels or parapets. Windward drifts occur when wind blows snow up against the higher portion of a building creating snowdrifts on the lower (windward) roof. Leeward drifts occur as snow blown from the higher roof deposits on the lower (leeward) roof. In addition, snowdrifts can form around roof obstructions such as penthouses, large mechanical units, solar arrays and rooftop gardens (green roofs).  A proper structural design must account for all of these conditions.

What about sloping roofs?  Can we slope a roof so we don’t need to design for snow loads?  Roof slopes can impact snow load design, but usually don’t reduce the design load on the sloped roof very much.  More often, sloped roofs add to the snow accumulation on an underlying roof or sliding snow from a sloped roof can cause damage to adjacent structures

The closer the ambient temperature is to freezing during a snowstorm, the higher the moisture content – and weight – of the snow.  Very heavy snows can exceed the code mandated loads and cause serious damage or partial collapse of roofs.  Abundant examples can be found in the northeast and east central states. Partial thawing of snow followed by rain or additional snow can significantly increase the applied loading as well.

Examples of extraordinary snowfalls that caused roofs to collapse

  • December 2010: Heavy snow and high winds ripped and deflated the Teflon roof of the Hubert H. Humphrey Metrodome in Minneapolis, MN.
  • January 2017: The roof of a conference center in Breckenridge, CO collapsed. The city had received 49 inches of snow the week prior to the collapse.
  • December 2018: The roof of a building in High Point, NC collapsed following a heavy snowfall.
  • February 2019: The roof of an online auction building in Oronoco, MN collapsed. The month was the fourth snowiest in Minnesota in 135 years.

Engineers are often challenged or questioned about “over-designing” buildings.  Truthfully, many buildings will never experience the loads they are designed for, however, when record snow falls occur and when huge, heavy drifts form, a proper design may be the only thing standing between you and a major business disruption. 

About the Author
Keith Jacobson has been President of VAA since 2003 and supports the growth of the firm’s expanding engineering and design services to meet the evolving needs of clients. With over 25 years of structural engineering experience, he works with owners and design-build contractors to optimize building systems in commercial and heavy industrial markets. Beyond his cast-in-place, post-tensioned and precast concrete technical expertise, Keith is a member of ACI 362 – Parking Structure, ACI 350 – Environmental Engineering Structures, the Minnesota Concrete Council and ACEC/MN Board of Directors.


Defense from Coast-to-Coast - High Wind & High Seismic Design

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The Importance of Goal-Setting in a Corporate Environment

As more corporations adopt formal goal-setting programs, it is important to understand how to engage staff in the process and how goal-setting can be used effectively to benefit individuals and companies overall. S.M.A.R.T. goals – statements that are Specific, Measurable, Attainable, Realistic and Timely – have become the standard for organizational goal-setting. Use of this method provides guidance for employees when proposing goals and
allows managers to more accurately judge the feasibility and later the progress of those goals. With a goal-setting program and engagement tools in place, companies will begin to benefit from the growth and additional skills of their employees.


After establishing a goal-setting program, it is critical to engage employees and managers in the process. Here are a few tips to encourage thoughtful participation when creating and executing S.M.A.R.T goals:

1. Write It Out

As a part of the goal-setting process, ask employees to write out their ideas before completing a formal document. Studies have demonstrated there are many benefits related to handwriting original content. Individuals are far more likely to remember the key details of a goal when asked to create it and write it down on paper. Written goals provide more than a starting-point for progress assessment; employees will be more likely to independently plan for and progress toward their goals.

2. Make It Fun

Allowing employees to explore a genuine interest or improve current skills of their choice leads to more engaged participants. If an individual has a key role in shaping their commitment, they will be more likely to accomplish it. Additionally, consider offering a personal goal for each employee. This goal, often unrelated to workplace skills, allows for a balance of work and play, demonstrating the company values well-rounded individuals.

3. Keep It Accountable

To get the most out of a goal-setting program, follow through with individual outcomes by adding mandatory meetings to review goal progress. Motivate staff with clear rewards for success and repercussions for little or no progress. While it’s important to incorporate this into annual reviews, consider introducing quarterly check-ins between the employee and direct supervisor. This will give employees built-in deadlines for progress and
gives managers the opportunity to provide advice and feedback throughout the year.


An inevitable part of trying something new is an opportunity to learn. The obvious learning opportunity is directly related to the goal. For example, an employee may set a goal to learn the latest version of a software program. In achieving proficiency in that program, they have learned a new skill. Even trying and failing comes with learning opportunities. However, in addition to goal-related knowledge, participants are developing skills in goal-setting and accountability that can benefit any position and any company. Everyone wants an employee comfortable setting goals and independently planning to achieve them.

As the goal-setting program becomes more established, employees and direct managers will learn how to effectively assess the feasibility of goals. Learning by doing, staff will gain a better understanding of what can be accomplished on an individual basis in the time allowed. It is also important to teach managers to discuss goals with their employees and create attainable goals by planning for other priorities throughout the year. Practicing communication in your organization through goal-setting will positively impact how employees on all levels share expectations for project work and related deadlines.

Obtaining leadership support can be accomplished through annual trainings. During these discussions, information about the S.M.A.R.T. goals system and tips on goal-setting can be shared in a way that is both informative and persuasive. This is a chance to share the values of the program – accountability, personal development, self-motivation – as well as preliminary steps for implementation.


Goal-setting raises the bar for performance in organizations. As mentioned earlier, growing different aspects of employee interests into skills – both professional and personal – benefits employee wellness and the company overall. Individuals who feel a healthy work-life balance have a higher tendency to stay and progress through the company. Goal-setting provides employees a natural opportunity to demonstrate leadership and self-motivation; typically leading employees to earn promotions. By using a goal-setting program to create clear avenues toward accomplishment, companies will develop happier employees that grow into skilled leaders.

As employees are promoted to leadership roles, their earlier interests may now benefit or be formally incorporated into organizational business plans. People are the catalyst for growth. By supporting personal goals, employees are empowered to develop the core of a business. Contributing individual drive to overall business goals can open the door on improvements from expanded service offerings to fostering a culture of wellness.


Goal-setting is a life-long skill. Continuing to encourage learning and self-motivation is a benefit to employees and, from a corporate perspective, will grow and enhance an organization as a whole.

About the Author

Mary Pettit is a Human Resources (HR) Manager leading organizational development and leadership training; managing employee relations; and building strategies to retain and recruit key talent for VAA. She welcomes and values the opportunity to contribute ideas to company-wide business goals and aligning HR initiatives and monthly wellness activities to foster employee camaraderie. Earning her first HR certification in 2008, Mary has continued in the field with a PHR certification from the HR Certification Institute and a Society of Human Resource Management (SHRM)-CP Certification.

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Playing by New Rules: How NFPA 652 Impacts Your Facility

According to the National Fire Protection Association (NFPA), 50 combustible dust accidents occurred in the United States alone between 2008 and 2012. To continue improving and reducing hazard risk in agricultural facilities, the NFPA reviews and updates their guidelines every three years. The latest, 2016 edition of NFPA 652 Standards for Combustible Dust introduces the
use of a Dust Hazard Analysis (DHA). This edition’s NFPA 652 update
impacts existing and new facilities that combat dust-related hazards as a result of their processes. The NFPA now advises commissioning a DHA once every five years.

What is a DHA?
A DHA documents potential fire, flash fire and explosion (or dust deflagration) hazards. All potential hazards are placed in one of three general categories: Not a hazard, Maybe a hazard or Deflagration hazard. In existing facilities, a licensed professional will conduct a site visit to observe the process, categorize potential hazards and provide any recommended administrative or engineering safeguards to reduce the risk of deflagration. For new facilities or facility expansions, a licensed professional can assess and incorporate safety measures in designs based on the local jurisdiction and building codes.

When considering commissioning a DHA, reach out to the Authority Having Jurisdiction and a licensed professional. These entities will confirm which codes and guidelines are used in the jurisdiction and if a DHA is required for a project. To perform the DHA and offer practical solutions, engage a licensed professional that specializes in the industry, such as an architect, mechanical engineer or fire protection engineer. A qualified professional will be knowledgeable about the facility process and have a thorough understanding of local and state codes.

Existing Facilities: Operations & Housekeeping Procedures
Often it is not the design, but the lack of consistent maintenance in existing facilities that pose risk. When conducting a DHA, the difference between the Maybe a hazard and Deflagration hazard categories is frequently proper maintenance and scheduled inspections of the equipment and associated safety features. To effectively manage hazards in a facility, DHA inspections will look for the following safety practices:

  1. Set schedules for cleaning and maintenance
  2. Cleaning thoroughness
  3. Lock out / tag out procedure for equipment cleaning
  4. Vacuuming for dust removal
  5. Pressure relief ventilation

New Facilities or Expansions: Considerations for Owners & Facility Managers
Part of the NFPA 652 - Annex B states the “purpose of a DHA is to identify hazards in the process and document how those hazards are being managed.” For new construction, earlier is best for making hazard management design decisions. Recognizing and addressing dust hazards in the preliminary design phase of a project can lead to cost and time savings. Including features in the initial facility design like appropriate ventilation and use of a vacuum system for dust removal will reduce the need for future retrofits. Keep maintenance and hazard management integrated in a project by considering the following questions in early phases:

  1. What dust hazard codes, standards or guidelines must be met in the facility design?
  2. How are potential hazards managed within the process?
  3. What maintenance and/or housekeeping programs will be needed for safe facility operation?

Learning from a Dusty Past
The continued development and updates of the NFPA guidelines are, at least in part, developed as a result of past, unaddressed facility hazards. As a preventative measure and code improvement, NFPA 652 recommends DHA inspections are conducted once every five years. However, only some state and local jurisdictions have adopted NFPA 652 as a requirement.

It is important to note the relationship between NFPA guidelines and the International Building Code (IBC). IBC dictates the industry standard and references other guidelines to bring new versions into their requirements. NFPA 652 is not yet directly referenced in the current IBC requirements. While this means DHA’s are not currently required by the IBC, there are a few compelling reasons to get ahead of the regulation.

  1. Safety
    Tracking and mitigating the accumulation of dust at your facility is critical to the safety of the operators. A DHA can help prove a facility is compliant or identify areas of concern and offer solutions. The painful results of ignoring potential dust hazards can include costly equipment failure, dust deflagration and, most importantly, loss of life.
  2. Project Schedule
    Depending on the local codes and jurisdictions, Code Officials may be working from the new guidelines. In that case, officials can deny a building permit if a DHA has not been completed. The delay will set new facility and expansion projects back in time and expense.
  3. Expert Predictions
    Based on the trend of previous updates, it is likely that the 2016 edition of NFPA 652 will be standardized and referenced in the IBC code by 2021. Keeping up with dust hazards and related guidelines will lead to safer facilities and fewer future project / maintenance hassles.


About the Authors
Doug Rohkohl
As a Senior Designer at VAA, Doug regularly works with owners and design-build contractors to design feed mills, grain elevators and other agricultural bulk material handling and processing facilities from early stages of project conception through final design and construction. Doug’s 15 years of experience in agribusiness has translated into a comprehensive understanding of how different construction methods; material handling and process systems; and the NFPA affect design. His favorite part of the job is meeting with plant managers at their facility to understand challenges and work together towards improving operations.

Eric Peterson
Eric has two decades of domestic and international experience, including feed mills, grain export terminals, flour mills, bulk storage facilities and specialty slipform structures. Versatile in managing both engineering and construction efforts, he understands the details needed to fulfill design, constructability,
procurement and cost estimating activities. A member of the NFPA, Eric’s knowledge of material handling, mechanical and structural engineering is complemented by his technical skills in AutoCAD, P6 and Hard Dollar. Prior to joining VAA, Eric worked for a design-build contractor where he developed design concepts with clients and coordinated design and construction efforts with equipment vendors and subcontractors. Clients appreciate his global understanding of the design / construction process to accomplish operational goals and challenging facility requests.