Montana-Dakota Utilities’ Heskett Station is adjacent to the Missouri River in Morton County, North Dakota. Due to several factors—the facility’s age, a high groundwater table, the absence of a positive drainage gradient toward a natural outfall, and the insufficient conveyance capacity of existing drainage infrastructure—rainfall and snowmelt frequently flooded the plant’s 115 kW switchyard. Because the floods created standing water adjacent to energized transformers, the situation posed a safety risk.

Barr was hired to determine the existing-conditions hydrology for the drainage area; use that to develop options for alleviating flooding; and prepare construction plans and specifications for the selected option. MDU needed a design that wouldn’t require upgrading an existing lift station, and that would receive buy-in from the facility staff members responsible for managing and operating the switchyard on a daily basis. A particular challenge was that work needed to be conducted within and adjacent to a fully energized switchyard containing overhead and underground cables, live gas lines, and other hazards, requiring a solution that could be implemented with small construction equipment.

Barr developed six options representing a range of implementation scenarios and costs to address the flooding issue. Working with facility staff and operators, MDU’s project manager chose the design that best accommodated workers’ needs and the utility’s budget.

Barr has provided geochemistry services, groundwater-monitoring network design, data review, and statistical analysis for Heskett Station’s coal ash landfill since 2010. When the U.S. EPA administered the Coal Combustion Residuals (CCR) Rule in 2015, we developed a compliance monitoring strategy, made network improvements to meet rule requirements, and instituted statistical analysis protocol for data evaluation. Since the rule took effect, Barr’s use of statistical methods, forensics, and institutional knowledge of the site geology and historical groundwater conditions has helped the client avoid costly corrective-action measures by determining that the parameters of concern were previously observed at elevated concentrations in soil and groundwater prior to construction of the coal ash landfill.

Barr developed and tested a “multiple working hypothesis” method to make an alternative source demonstration that documented lines of evidence showing that current observed conditions were consistent with historically elevated concentrations. We have since used this method to make several alternative source determinations under the CCR Rule, which has helped our client avoid unnecessary and costly action to remediate groundwater under the rule. In addition, Barr’s experienced data-quality-assurance team identified laboratory and sampling inconsistencies, which provided additional evidence that the downgradient detections were false positives.

Battle Creek is a perennial, urban stream located in the western Twin Cities metropolitan area of Minnesota. Historically, the creek was plagued by frequent floods that caused heavy erosion. To address this, the Ramsey-Washington Metro Watershed District initiated a large erosion-control project in the early 1980s. Since project completion, bank erosion and channelization have significantly reduced. However, the population and diversity of fish and macroinvertebrates within the stream’s ecosystem have not similarly improved. In 2014, Battle Creek was added to Minnesota’s impaired waters list for biological impairment of the fish and macroinvertebrate communities.

Working with the district and the Minnesota Pollution Control Agency (MPCA), Barr analyzed water-quality data and fish- and macroinvertebrate-survey information collected over the past 30 years to develop a stressor identification report. Following the U.S. EPA’s Causal Analysis/Diagnosis Decision Information System stressor-identification process, various measures of biological integrity—index of biological integrity, tolerance indicator values, biological metric analytical techniques, etc.—were compared to water quality data to determine which ecological stressors (e.g., turbidity, low dissolved oxygen, heavy metals, etc.) were primarily responsible for biological impairment within the stream ecosystem.

The report was submitted and approved by the MPCA in 2016. Following recommendations in the report, a total maximum daily load (TMDL) for total suspended sediment was developed and completed in 2016. The TMDL report has been submitted to the MPCA and is under final review.

The Lower Rouge River Old Channel (LRROC) is a heavily industrialized navigation channel in southwest Detroit. In 2019, the U.S. EPA and the U.S. Army Corps of Engineers undertook a joint project to address environmental impacts in the LRROC and maintain its depths as a federal navigation channel by removing contaminated sediment and large debris. Great Lakes Dock and Materials, the company hired by the Corps to complete the dredging, turned to Barr to provide monitoring services for both the water quality of the channel and the structures adjacent to dredging locations.

During dredging, Barr deployed water-quality monitoring buoys in the channel that continuously collected turbidity readings. Data from the buoys was sent to a remote website, which sent automated email and text alerts to project stakeholders if the channel’s turbidity exceeded a certain threshold. If an alarm was triggered, Barr evaluated the data to assess the cause of the alert. When readings indicated that the water-quality parameters had been exceeded, we relayed the information to Great Lakes Dock and Materials to modify construction methods to mitigate water-quality impacts.

For the structural monitoring portion of the project, Barr evaluated bridges, sheet pile walls, buildings, and foundations adjacent to the dredging area. After this initial documentation, we evaluated the structures monthly throughout dredging. We also installed instrumentation adjacent to a lengthy sheet pile wall that continuously collected measurements on the wall’s movement. These measurements were uploaded to a remote monitoring website, which sent alarm notifications to on-site and engineering support staff based on the allowable movements stated in the project specifications.

Barr initiated the monitoring programs in 2019 and continued to support the project until construction was completed in the fall of 2024.

The city of Little Falls’ wellfield is very close to the Mississippi River, and a significant portion of the water pumped by the city’s wells comes from the river. This connection to the river requires that the city’s wellhead protection plan include management actions not normally included in such a document.

Barr developed a new groundwater model for the area and helped the city obtain a Minnesota Department of Health grant to cover part of the model-development cost. The new model was used to estimate the percentage of water pumped by the city’s wells that comes from the river and to delineate the wellhead protection area.

When a tornado passed through this wind project at a speed of 166 miles per hour, it caused extensive damage to several wind turbine generators. The client turned to Barr to evaluate wind turbine foundations at the site. We began with a preliminary visual inspection. In one instance, the tower and turbine components for one foundation had not yet been fully assembled, and a crane next to the foundation had collided with the assembled parts. At another foundation site where the tower and turbine components were fully assembled, we observed cracks in the grout below the tower’s bottom flange.

Based on these preliminary findings, Barr completed an additional inspection and oversaw nondestructive testing (NDT) to evaluate a group of additional foundations located in the tornado’s path. This work included NDT examination of one foundation, dynamic-response-analysis testing of 12 more foundations, and a review of anchor-bolt tension checks completed after the tornado struck.

The data obtained from the dynamic response analysis justified a level of confidence that the foundations supporting turbines with damaged blades or other components were not significantly damaged and were behaving similarly to the foundations with no observable damage.

Six of our client’s water-supply wells pump water from a groundwater plume containing chlorinated solvents. Those wells serve as a city’s primary water-supply source and as a remediation system to control the migration of the groundwater plume.  The solvents in the extracted water are removed to non-detectable concentrations using granular activated carbon (GAC) in a Barr-designed treatment plant.  In 2014, the compound 1,4-dioxane was detected in the treatment-plant effluent at concentrations above the health-based value set by the Minnesota Department of Health. For the client to continue drawing this water for potable use, additional treatment was required to remove 1,4-dioxane.

Barr designed and operated an eight-month pilot study to evaluate two advanced oxidation process (AOP) technologies for removal of 1,4-dioxane—low-pressure UV/peroxide and ozone/peroxide.

Pilot testing indicated that both AOP systems remove dioxane to target limits. In this application, the ozone/peroxide system was eliminated due to production of undesirable bromate concentrations as a byproduct of the reaction of naturally occurring bromide and ozone. High levels of bromate in drinking water have been associated with elevated health risks. Following pilot testing, Barr designed the full-scale treatment-plant modifications, which were completed in 2019.

In 2019, an industrial client received a notice from the Great Lakes Water Authority (GLWA) indicating that its wastewater discharge could be a major contributor to the mass loading of per- and polyfluoroalkyl substances (PFAS) to the local wastewater treatment plant. The GLWA informed the client that it needed to take on a PFAS reduction strategy, so the client turned to Barr to help identify and reduce the PFAS content found in its process.

Barr worked with the client to address the loading by identifying the potential sources through mass balance sampling. This included evaluating the facility process and previous sampling conducted by the GLWA. Due to the varied inputs in the process, we determined that the samples collected by the GLWA were not adequately characterizing the PFAS content of the discharge, and we worked with the facility to implement a more representative collection technique. The results demonstrated that the PFAS data presented by the GLWA were not representative of the facility’s actual discharge. The segmented mass balance sampling also showed where the intermittent PFAS detections were occurring in the process, so we recommended changes, such as more frequent cleanouts and service on the client’s internal processes, that could address the issue for the long term.

Learn more about our PFAS engineering and environmental capabilities.

(stock photo shown above)

Just south of Bismarck, the University of Mary stands atop a 175-foot-tall bluff overlooking Apple Creek and, farther out, the Missouri River. The campus’s first buildings, designed by celebrated midcentury-modern architect Marcel Breuer, frame the sweeping landscape through generous windows, angular outdoor structural elements, and cutouts in concrete walls.

The Sisters of the Annunciation who founded their monastery and school in the 1950s were keeping up the Benedictine tradition of building communities on inspiringly high ground, but there was little awareness at the time that slopes along North Dakota’s river valleys have their own tradition: succumbing to landslides, due to layers of weak clay and groundwater. The bluff supporting the campus, which Breuer referred to as the Jewel of the Prairie, would gradually begin deteriorating in a phenomenon known as “rotational slump.”

In 2015, the University of Mary, in cooperation with the North Dakota Department of Emergency Services and the Federal Emergency Management Agency, began working to address three landslides posing risks to the campus—not only the historic Breuer buildings, but several that had been added in the intervening decades, as well as a cemetery where the monastery’s nuns are laid to rest.

In late 2021, Barr began studying and designing stabilization measures for the largest landslide, which over the years had been advancing toward the cemetery. In a preliminary geotechnical assessment, we fed existing subsurface-drilling, groundwater-monitoring, and lidar data into GeoStudio’s SLOPE/W software to develop an initial model of the slope and evaluate options for stabilizing it. The model indicated that a combination of approaches would be necessary to halt the landslide.

Barr then conducted an in-depth geotechnical investigation that included new soil borings to collect a variety of samples as well as to install inclinometers and vibrating-wire piezometers that measured subsurface deformation and groundwater pore pressures, respectively. The soil samples were tested in a laboratory to characterize shear strength, permeability, and soil chemistry, and we incorporated the resulting data into a final seepage, stability, and deformation model created with the advanced numerical modeling program FLAC. The model also allowed us to account for the interaction between soil and structural stabilization elements known as auger-cast piles (11 vertical steel rods surrounded by a spiral steel cage set in cement grout).

The geotechnical investigation and analysis confirmed that two approaches were needed to stabilize the slope:

1. removing more than 70,000 cubic yards of earth from the top portion of the landslide

2. installing 65 piles extending as deep as 75 feet below the surface to anchor the soft, sliding soil mass to the stronger, more stable ground below

Over the summer and early fall of 2023, about half the earth excavated from the upper portion was shifted to the lower slope, which reduced the steepness of the original grade by nearly 65 percent, and the auger-cast piles were installed to inhibit future ground movement while raising the slope’s factor of safety by 25 percent.

Together, the measures will minimize further slumping at the bluff—preserving the unique architecture of the university buildings and monastery, as well as the cemetery honoring the nuns who established the community and taught and served at the school.

In June 2011, the Mouse River flooded, causing the evacuation of more than 11,000 people and more than $700 million in damages. In response, Barr and a team of subconsultants completed preliminary design for flood-risk-reduction system improvements throughout the river valley. Construction of phases 2 and 3 in Minot, which represent nearly two miles of flood-risk-reduction features, was completed in fall 2020.

One part of Barr’s design work involved park and landscape design. We worked with the City of Minot, the Minot Park District, and the U.S. Army Corps of Engineers to design trails on the flood-risk-reduction system’s levees. We also designed a dog park, streetscapes, and parking lots while collaborating with the park district to set priorities for park features and layout. In addition, we developed a landscape management plan; created resilient plant communities that can thrive on the area’s dry, exposed slopes and in the river floodway; and selected tree species for streets, parks, and the floodway.