A History of Excellence


American Engineering Testing (AET) was founded by Terry Swor, PG, Donovan Stormoe, PE, and Richard Stehly, PE, in 1989 in Roseville, Minnesota. Their careers were built by attaining leadership positions at another significant and nationally known Minnesota-based firm, Twin City Testing Corporation (TCT), until a UK-based firm acquired it in 1984.

Together, they embarked on a plan to create a different kind of engineering firm that placed a high value on skilled professionals and technicians with tried and true business relationships in their areas of expertise. In 1989, AET acquired the 17-person firm, Geotechnical Engineering Corporation, the first step on its way to becoming one of the largest, comprehensive geotechnical, environmental, construction materials, building forensics and NDT engineering and testing services firms in the Upper Midwest.

In early 1990, AET moved to its current location in the Midway area of St. Paul. The five-acre parcel destined to be their corporate headquarters was strategically placed at the border between Minneapolis and St. Paul. The trio invested significant resources in master planning, knowing that sufficient space would be needed to support future growth in staff and facilities. The principals and senior technical leaders leveraged a strong legacy of experience in their fields throughout the Upper Midwest.

To attract and retain the best talent in our industry, AET was structured as and remains an employee-owned S-corporation through its Employee Stock Ownership Program (ESOP). The firm is completely owned by its staff through an internal plan called ASSET (American Stock Saving Employee Trust). We emphasize training and mentoring to attract and maintain the most qualified personnel for consulting and laboratory services for our client partners in a broad spectrum of industries. Our firm is known nationally and internationally for its broad scope of services, thanks in part to Richard Stehly, who served as a president of the American Concrete Institute (ACI) and lectured in 25 countries on ACI's and AET's behalf. Unfortunately, Stehly passed away in 2010. Stehly and Swor were also instrumental in launching AET's petrography business in 1990.

We honor founder Donovan Stormoe's belief in life-long learning within our firm through our Donovan Stormoe Training and Development Center, which is consistently open to members of the A/E/C community for professional events. Stormoe was the first person from AET to become President of ACEC/MN. Other individuals from AET attaining this position include Robert Pendergast, PG/PE, Donovan Stormoe, PE, and Robert Struve, PE, and Daniel Larson, PE, our current CEO.

Terry Swor remains an advisor to AET after his retirement and embodies the firm's culture of engineering excellence, longtime professional connections and community service. Swor has received both the President's Award and Tom Roche Award given annually by ACEC/MN for his dedication to and advocacy for the consulting engineering community. In 2014, Swor received the Richard Stehly Industry Advancement Award by the Minnesota Concrete Council for his dedication and research in the cast-in-place concrete/cement industry.

Growing to Serve

In the early 1990s, we opened our first regional offices in Duluth and Mankato, Minnesota. Three years later, facilities in Rochester, Minnesota and Wausau, Wisconsin, opened, and were followed by new offices in Marshall, Minnesota, and Pierre, Sioux Falls and Rapid City, South Dakota.

AET's in-house quality assurance/quality control program was established in 1993 to systematically and rigorously audit departments and offices/labs on test procedures, calibrations and test accuracies.

AET has always been committed to growing sustainably and in ways that benefit clients, strengthen service offerings, maintain company culture, and benefit our employee-shareholders. 

In 2006, we bought the major assets of another leading consulting engineering firm with a staff of 65, GME Consultants, and added considerable engineering, environmental and technical talent to support our growth. Through the acquisition, we gained new office locations in International Falls, Minnesota and Menomonie, Wisconsin. The Albertville, Minnesota office opened in 2007, followed by Green Bay, Wisconsin in 2010.

On August 2, 2010, we took another strategic step in plans to increase our capability to serve clients in Wisconsin and South Dakota by acquiring certain selected service lines from competitor Tetra Tech, Inc. in Chippewa Falls, Wausau, and Seymour in Wisconsin, and Sioux Falls, South Dakota. These service lines included geotechnical and construction materials engineering/testing, drilling and water chemistry disciplines.

In 2011, to take advantage of opportunities fueled by the oil and gas industry boom in North Dakota and eastern Montana, AET opened offices in Dickinson and Williston, North Dakota.

In 2013, AET added specialized chemistry services in St. Paul, including Infrared Spectroscopy, X-Ray Fluorescence, X-Ray Diffraction and wet chemistry to support the concrete, aggregate, construction materials and cement specializations of our Petrography Laboratory.

In 2017, AET opened an office in Sheridan, Wyoming bringing environmental, geotechnical engineering and materials testing services to our clients in the Rocky Mountain Region. 

In 2020, we expanded our geographic footprint in the West Region with the acquisition of three offices from a competitor, Strata, resulting in new offices in Gillette and Casper, Wyoming and additional staff in Williston, North Dakota. 


The American Council of Engineering Companies (ACEC) of Minnesota honored AET in 1991 with its first ever "Firm of the Year" award, demonstrating AET's industry leadership early in its history. AET was again honored with the "Firm of the Year" award in 2006, the first two-time winner.

More recent awards include:

     2019 ACECMN Engineering Excellence Award: The Promenade of Wayzata 
     2019 ACEC Honor Award: The Promenade of Wayzata 
     2019 ACECMN Engineering Excellence Award: 
TH 169 Nine Mile Creek Bridge Design-Build
     2018 ACECMN Engineering Excellence Grand Award: Downtown East
     2017 ACECMN Engineering Excellence Grand Award: U.S. Bank Stadium
     2017 ACECMN Engineering Excellence Honor Award: Hamline Station

     EDAM Redevelopment Award

     Concrete Paving Association of Minnesota Merit Award
     Midway Chamber of Commerce Large Business of the Year Award

To learn more about AET, visit our Services pages or choose a market sector to explore.