Sept. 29, 2021
Newsline Home Newsline Archives Print Newsline Submit News Feedback About Newsline iHub Home Web site

Table of Contents


Print Newsline
SELECT ALL or Click checkboxes below to select articles you wish to print.
Use your browser's Reset Button to deselect all.

Geotechnical drilling provides glimpse into soil, rock below work sites

Photo: a worker standing next to a large drilling rig

Pat O’Donnell, field crew chief, prepares a drilling fluid (made of clay and water) at a geotechnical drilling site near Hwy 60 in St. James. The fluid, pumped into a drilled hole in the ground, keeps the hole from collapsing once groundwater is reached. MnDOT staff photo

By Joseph Palmersheim

Rich Lamb says there is a classic joke at geotechnical engineering conferences that is often used to start a presentation: “If you look up the word ‘boring’ in the Yellow Pages, the entry reads, ‘See geotechnical engineers.’”

From Lamb’s point of view, geotechnical engineering is “probably anything but boring.” Quite the opposite, actually.

“I don’t think I could have found a more interesting job at MnDOT,” he said.

Lamb, state foundations engineer, is one of 14 people assigned to the Foundations Unit of the Geotechnical Engineering Section, which is part of Office of Materials & Road Research in Maplewood. These employees perform a variety of tasks including field work, laboratory testing and engineering analyses. They take a good look at the earth to determine if the soils are capable of supporting bridges, retaining walls, large drainage structures and other transportation-related structures.

“You need to investigate what’s underground,” Lamb said. “Say we’re building a new road somewhere, and you didn’t do an investigation before you place a 25-foot embankment. If the site contained poor soils, you’d at a minimum have settlement problems, and the pavement would have to be replaced much more frequently. As another example, bridges can be supported on deep driven piles or on shallow-spread footings. That’s the main thing – which will we use? If we choose deep-driven piles, the Bridge Office will want to know how long they’ll be, to estimate cost. If a standard bridge costs $1 million, foundations can cost up to $50,000.”

Foundation Unit field crew workers drill into the ground to gather soil and rock samples, which are classified and tested for strength and compressibility in the Foundations Unit lab.

These crews work on the road from Monday to Thursday, traveling wherever their services are needed and working year-round in all types of weather. In a typical year, they’ll work on 12-15 bridge projects, 20-25 culverts, and other miscellaneous work. It’s a skill that’s needed for something as small as a culvert or as large as the Interstate 35W@94 project.

Photo: map showing drilling coordinates

X marks the spot: Drill crews are given GPS coordinates like these to show exactly where on a site to drill. The average bore hole for bridge investigations is around 75 feet, and some go as far down as 150 feet. MnDOT staff photo

The first step is knowing where to drill.

Geotechnical engineers choose where borings and samples are needed. Drill crews are given GPS coordinates, and any site utilities are marked by Gopher One before the crews starts drilling.

The average bore hole for bridge investigations is around 75 feet, Lamb said, and some go as far down as 150 feet.

“We sometimes have to set up the drill rig in very difficult terrain,” Lamb said. “Our drill rigs are tracked, like a tank, and they can go most anywhere, except really steep slopes. Normally, we’ll be using a lot of drill rods to get deep enough. The main purpose is to get samples back so you can test and classify them.”

A 50-foot boring can take a day or day and a half. A lot of this time is spent getting to the site and setting up. The drilling doesn’t take too long. Depending on conditions, crews can go through 10-20 feet of soil an hour. Rock drilling is much slower.

To retrieve a soil sample, field crews use a hollow 18-inch-by-2-inch cylindrical sampling tube called a split spoon sampler, similar to those in use for the past 100 years. Once the desired sample depth is reached, the drilling stops, and the sampling tube is hammered into soil as part of standard penetration test. This gives an idea as to the soil’s density (with the number of hammer blows per foot) and also fills up the sample tube.
Sampling bedrock is quite different. The rock must be cored using a rotating sharp-edged sample device called a core barrel. While it may seem counterintuitive, it’s easier to core through hard rock like granite, Lamb said, because the material stays more intact than softer, less cemented, rock like sandstone.

And naturally, the earth doesn’t always cooperate with someone trying to drill a hole in it. To keep bore holes from collapsing, especially below the groundwater table, drill crews use a drilling fluid (a mixture of natural clay and water) that is pumped into the borehole to keep it from closing. This requires water, which the crews have to bring with them.

“In addition, anytime we drill, we have to submit a record to Department of Health showing that we sealed the hole, and that it’s not hollow,” Lamb said. “They don’t want contaminants getting into the ground.”

While each district has capacity to do shallow roadway boring for pavement investigation, they use smaller drill rigs and different drilling equipment, typically drilling less than 10 feet down, looking just below the pavement. With geotechnical drilling, MnDOT crews go down much deeper, sometimes through millions of years of sediment.

“You have to think about the glaciers that covered the state more than 10,000 years ago,” Lamb said. “The glaciers did a lot of the depositing of soils and scouring, and the bedrock was here before that. I’ve learned a lot about geology during my career. Sometimes you find cow bones. I think we found a piece of pottery once. You’ll find layers of wood. Once, while working on the St. Croix River Crossing project, we found thick layers of wood and sawdust, and it turns out there had been a lumber mill where we were drilling.”

Nearly 30 years into his career with MnDOT, Lamb is still learning new things about drilling and geotechnical engineering. Even as a child, he had a strong interest in exploration and discovery.

“We don’t know what’s below the ground. That’s fascinating to me - that we can move out to a site and return some soils and show people what we found, which can affect how a bridge is designed and built. It’s overwhelmingly satisfying.”



Jenny Krantz named new Safety Rest Area program manager

Photo: Jenny Krantz.

Jenny Krantz. Submitted photo

Jenny Krantz is MnDOT’s new Safety Rest Area program manager. This program focuses on Class I, II and III rest areas, including long-range planning and budgeting. In addition, she manages special projects related to the program and collaborates with her peers in other state DOTs.

Krantz graduated from North Dakota State University with a bachelor’s degree in landscape design. She worked as a private sector landscape architect for 12 years before joining MnDOT in 2019.

Her first day in the new role was Sept. 10.

Robert H. Williams, site development unit supervisor, served in the role prior to Krantz.



What's New on the Web

How does transportation affect the health of people, the environment and the economy? What climate goals have MnDOT recognized as essential for the future? How is the agency working to make your community healthier? Find out by visiting the new “MnDOT and Public Health” webpage. On this new site, MnDOT’s Sustainability and Public Health Division explores how transportation relates to health and climate goals and shares the agency’s focus areas.

Created in 2019, the Sustainability and Public Health Division is helping the agency prioritize safe, convenient and affordable transportation options. These help connect people with schools, jobs, friends and family, and essential needs like healthy food, recreation and health care.



New library materials available

The latest issue of New Library Materials is available. This issue features “Work Disrupted: Opportunity, Resilience, and Growth in the Accelerated Future of Work,” by Jeff Schwartz, Suzzane Riss and Tom Fishburne. New Library Materials is a compilation of resources added to the library collection during the previous month.

Visit and click “New Library Materials” to sign up. Questions and feedback are welcome at Ask a Librarian.



MnDOT groups engage with visitors at Fiesta Latina

Photo: a MnDOT booth at a community fair

MnDOT’s Latino-American Employee Resource Group and STEM Education and Outreach staff sponsored a booth at Fiesta Latina in St. Paul on Saturday, Sept. 18. Visitors learned about current job opportunities and available K-12 educational outreach resources, and some took a spin on the wheel for promotional items. Pictured managing the spinning wheel is Frida Alvarez, diversity and inclusion organizational development specialist, Office of Equity and Diversity.

The Latino-American ERG is dedicated to encourage and strengthen MnDOT employees of Latino descent for positive recruitment, career building and retention purposes. Learn more about LAERG on iHUB. Photo by Marcia Lochner


Students see plow, build bridge kit at District 6 career fair

Two photos: top photo shows students looking at a MnDOT plow, and bottom photo shows two students building a model bridge

More than 500 students from eight District 6 area high schools in southeast Minnesota explored one of MnDOT’s plow trucks and raced to see who could build the bridge-in-a-bag kit the fastest at the Bluff Country Collaborative regional career fair outdoors at Caledonia High School on Thursday, Sept. 23. The fastest team to build the bridge did so in only 8 minutes and 58 seconds. Photos by Cindy Morgan


On the Job: Katie Haun Schuring preserves Minnesota’s history

By Joseph Palmersheim

Photo: Katie Haun Schuring

Katie Haun Schuring, Cultural Resources Unit historian and supervisor with the Office of Environmental Stewardship, is pictured inside of the Third Avenue Bridge in Minneapolis. Photo by Elizabeth Gales

Katie Haun Schuring is a Cultural Resources Unit historian and supervisor with the Office of Environmental Stewardship. She reviews all federal- and state-funded transportation projects to ensure that the work proposed doesn’t harm any significant building, structure or archaeological site.

How long have you worked for MnDOT?
I’ve been with MnDOT for four years. Prior to coming to the state, I worked for a private consulting firm conducting historical survey, writing contexts and rehabilitating bridges to the Secretary of the Interior’s Standards.

How would you describe your role?
My specific specialty is in historic bridge rehabilitation, where I help project engineers and project proposers (districts, counties, etc.) with developing plans that sensitively restore bridges throughout the state. By doing so, we are maintaining our engineering heritage and are able to tell the story of how people used to travel throughout Minnesota.

How far back does MnDOT’s history go?
The history of MnDOT and a transportation organization goes back over 100 years. In the early 20th century, most roads were owned and maintained by cities and counties. It wasn’t until 1921, following a constitutional amendment, that a system of trunk highways was established. The Minnesota Highway Department managed the trunk highway system then and in the 1970s formally changed its name to the Minnesota Department of Transportation. MnDOT has a great historic chronology on the development of roads in the state.

What resources or documentation do we have to help tell MnDOT’s story?
Historians use a lot of different resources when we are learning the history of a property, including historic maps, aerial photographs and documents. Often local libraries and historical societies have books, newspapers, city directories and other information that we look at to determine if a property is eligible for the National Register of Historic Places. For MnDOT-specific information, check out the MnDOT library. It is a great resource for old documents, including annual and biennial reports beginning in 1920.

When did you realize you liked history and why did you decide to pursue that as a career?
I’ve always loved history, even as a little kid. I went to college to study history but wasn’t 100 percent sure what I was going to do after school. I had a great advisor who told me about historic preservation, which could combine my love for both history and architecture (my second favorite thing). So, after graduating from college, I went to graduate school to study architectural history and historic preservation.

What are some of the projects you are working on?
Current projects I’m working on include the relocation of the historic Kern Bridge (South Bend Township in Blue Earth County), Rethinking I-94 and the rehabilitation of the Third Avenue Bridge (in Minneapolis) and the Stewart River Bridge (in Two Harbors). I’m also working on some interesting historical studies of railroad corridors and of bridges constructed from the 1970s to the present.

What’s an average day like for you?
My day is filled with answering questions about historic bridges and road projects, writing findings letters, managing contracts, reviewing consultant work and overseeing staff. The days are busy but so rewarding!

Do you or a co-worker have an interesting job to share with readers? Send us your ideas, and we’ll contact you for more information.

Recent employee profiles:


SELECT ALL or Click checkboxes above to select articles you wish to print.
Use your browser's Reset Button to deselect all.