To evaluate vapor intrusion near a site with groundwater impacted by chlorinated solvents, primarily trichloroethylene (TCE), our client hired Barr to assist with a large-scale vapor intrusion investigation in a residential area. Using a tiered approach following the Minnesota Pollution Control Agency’s (MPCA’s) risk-based guidance, we first performed a desktop screening-level vapor-intrusion study to determine that vapor intrusion represented a potential concern and required further investigation.

Barr then collected soil-gas and groundwater samples in public rights-of-way to further evaluate the potential vapor intrusion risk and define areas where building-specific data was needed. This information indicated that building-specific data was needed from approximately 300 properties.

As part of the building-specific sampling effort, Barr communicated with property owners and building occupants regarding sampling, obtained access agreements, and scheduled appointments. Each property was assigned a “property coordinator,” a Barr staff member who followed the property through the life cycle of the project, including communicating with property owners and building occupants, obtaining access agreements, scheduling sampling appointments, and communicating sampling results. Due to the large number of properties, communications with property owners and other property-specific data were documented in a database for frequent reporting to our client and regulatory agencies.

This personalized approach resulted in participation from 95 percent of property owners. Barr’s sampling technicians used manually operated drills, vapor-pin sample ports, leak-testing methods, and Summa canisters to collect sub-slab soil gas samples. Indoor air sampling was also completed at selected locations.

Based on the results, active sub-slab depressurization mitigation systems were installed at more than 185 properties. Barr observed the installations and also observed and documented post-installation diagnostic testing to confirm the effectiveness of each system.

Barr performed a wastewater antidegradation analysis for a large chemical producer and prepared an application for renewal of the facility’s NPDES permit.

ANTIDEGRADATION ANALYSIS: Because our client was anticipating an increase in its rate of organic pesticide production, an antidegradation analysis was needed to discover if that would negatively affect the receiving water body or require changes to the facility’s discharge permit.

We began by determining the facility assimilative capacity (FAC), conducting a pollutant-by-pollutant evaluation of the amount of each substance that could be discharged to the receiving water without exceeding the water quality standard. We then calculated how much of the FAC would be consumed by the increase in production. In accordance with the state’s antidegradation implementation procedure, we evaluated the parameters—including those imposed by federal effluent limitation guidelines (ELGs) the facility was subject to—which were:

We determined the FAC for each pollutant according to state water quality criteria; however, where numeric criteria were not available, we used other methods of establishing comparison values. For biochemical oxygen demand, we employed a previous Streeter-Phelps model to derive the dissolved-oxygen impact and compared the result to the state criteria, which showed that the proposed condition would not cause a dissolved-oxygen excursion. For total suspended solids, Barr used existing data on the receiving water body to propose a site-specific comparison value for the FAC, which indicated that the proposed rise in production would not significantly increase suspended solids in the receiving water.

Overall, the antidegradation analysis found that the planned production increase would be minimally degrading to the receiving water body: for each pollutant, the change in water quality was well below 10 percent of the FAC.

NPDES PERMIT RENEWAL APPLICATION: Before starting to prepare the application for renewal of the facility’s NPDES permit, Barr and the facility met with staff from the state regulatory agency to establish goals and timelines for the application and to document any recent changes in permit procedures. The meeting helped establish open communications with the agency staff, which later helped prevent delays and reduce uncertainty in the permitting process.

Barr performed a mixing-zone study for the facility’s primary receiving water body by aggregating flow data from a nearby U.S. Geologic Survey stream gage and calculating 1Q10, 7Q10, and 30Q10 low-flow values at the discharge point (the lowest 1-, 7-, and 30-day average flows that occur (on average) once every 10 years. With those data and bathymetric cross-section information, we generated CORMIX model scenarios to determine the effluent mixing at each flow scenario for the primary outfall. The revised model indicated that there was enough mixing that the discharge would not cause violations of water quality criteria.

Next we generated a parameter table for each outfall, which showed what analytical data would be needed to complete the application. After reviewing existing data from the facility’s discharge monitoring reports and internal monitoring, we identified gaps in the data and recommended additional sampling. Once all necessary information had been collected, we completed the application forms and worked with our client to submit them before the deadline.

In addition to the permit application, Barr developed a background-information document to help state regulators understand the complexities of the facility in relation to its wastewater discharge. The document included detailed information about: 

The permit is currently under review by the regulatory agency.

The Brickyard area of Lilydale Regional Park is a place of historic and recreational significance to the city of Saint Paul. Slope instability and decreased water quality in downstream Pickerel Lake (which drains to the Mississippi River) prompted the city to hire Barr to study slope-stability and erosion issues and develop concept-level recommendations for slope stabilization, stormwater management, and erosion control.

After a large slope failure toward the north end of the study area (the North Knob), we collected soil borings and conducted geotechnical modeling to evaluate the influence of topography, soil strength, and seepage and saturation on slope stability. We also developed a hydrologic and hydraulic model to assess drainage patterns in the area and their effect on erosion.

Barr reviewed a history of previous landslides and assessed existing conditions for the risk of large-volume landslides, soils falling from significant heights, and people being caught in a slide from above the failure surface. No area of the park was considered to be without risk, since the uncertainties of weather, soil type and strength, and human activity always pose some risk of unexpected soil movement. Identification of high-risk zones, however, has helped the city manage public access to certain areas of the park. The city is in the process of implementing a series of recommendations from Barr, including stabilization of the North Knob and a small stream channel that crosses the area.

Built in the mid-1990s by the U.S. Army Corps of Engineers, the existing levee flood control system protected the city of Alvarado in 1997, 2005, 2009, and 2010. Even though the levee system has performed adequately since its completion, has been well maintained, and has been shown on Federal Emergency Management Agency’s current flood insurance rate maps (FIRMs) as providing protection from the 100 year flood (base flood), FEMA requires documentation be submitted that demonstrates that the levee system, including operations and maintenance procedures, meet the requirements of Title 44 of the Code of Federal Regulations (CFR), Section 65.10 (44 CFR §65.10), titled “Mapping of Areas Protected by Levee Systems.” The compliance documentation must include design criteria (i.e., freeboard, closures, embankment protection and stability, foundation stability, settlement, interior drainage), operations, and maintenance.

The city hired Barr to perform a preliminary engineering assessment of the existing levee system relative to 44 CFR §65.10 and identify remedial measures for the city’s interior drainage concerns and needed improvements to correct other deficiencies discovered during the engineering assessment. Detailed hydrologic, hydraulic, and geotechnical analyses conducted during the preliminary engineering phase of the project revealed that modifications to the existing levee system are required in order for the flood protection system to obtain FEMA accreditation and to meet current USACE design criteria. The city also requested that Barr design, permit, and implement the needed levee system improvements. Since the improvements include modification to the existing federally built levee system, the improvements were designed in accordance with USACE standards and require 33 USC 408 approvals.

To address levee deficiencies and restore the city to the USACE levee safety program, Barr developed and received USACE approval of a System-Wide Improvement Framework (SWIF) Letter of Intent (LOI)

Upgrading the flood protection system consisted of the following major tasks:

The project was completed in summer 2014 and FEMA certification was completed in early 2015.

Parks Canada manages highways that pass through the country’s national parks; the roads serve as critical socioeconomic corridors for tourism and commercial transport. Highway 16 in Jasper National Park helps attract 5 million visitors each year to the mountain national parks. The agency is undertaking work to improve overall highway asset conditions. Barr has been contracted as the environmental consultant for this effort. One project the agency proposed was the construction of a passing lane along Highway 16 to remedy the lack of passing opportunities due to the roadway geometry. 

Barr completed a detailed wetland assessment and impact report, which included delineating, classifying, and assessing wetland areas. In addition, our work encompassed the classification of soil and vegetation communities; surveys of wildlife and sensitive species; assessment of wetland ecological function; and mitigation of impacts within the wetland. Barr recommended impact mitigation options for the project that were in accordance with the Alberta Wetland Policy, the Canada National Parks Act, and the Species at Risk Act.

A transformer fire at a wind farm in New Mexico damaged the foundation of one of its wind turbines. After taking the tower out of service, the client hired Barr to evaluate the fire damage and determine its effects on the foundation’s structural integrity.

Our inspection and analysis of the foundation’s concrete and the steel anchor rods began with a survey of engineering literature for guidance on the permanent effects of fire on structural steel performance. This directed our plan to assess the effects of the fire on the anchor rods.

We worked with a subcontractor to visually inspect the foundation concrete of the wind turbine pedestal and perform materials testing. The subcontractor conducted concrete coring and petrographic analysis. The inspections showed evidence of charring on the pedestal concrete nearest the fire. The petrographic analysis found that while the outer surface of the concrete pedestal suffered thermal cracking, the fire had induced no chemical change. We tested the anchor rods using tension testing and a second method that involved use of a surface-hardness tester to estimate the anchors’ tensile strength. Our research, testing, and analysis indicated that the anchors could be reused with no expectation of reduced performance and that the concrete pedestal suffered no degradation from the fire.

We recommended cosmetic repairs, original grout removal, and clean-up of loose concrete and other debris. After these repairs were completed (and the transformer was replaced), the client placed the turbine back into service without incident.

Alberta Environment and Protected Areas maintains an organizational system of land-use regions that correspond to the province’s seven major watersheds. Each region is required to prepare a comprehensive land-use plan for managing natural resources in ways that support the province’s long-term economic, environmental, and social goals.

During development of the plan for the North Saskatchewan region, an assessment of existing data revealed that lake morphometrics — quantitative information on the sizes, depths, and volumes of lakes — were missing from AEP’s GIS database. That information is crucial to characterizing lakes and modeling the quality of the water in them, but it was available for only two dozen of the 839 lakes listed in the database.

Although two-dimensional data on the shapes and areas of lakes was relatively easy and inexpensive to obtain by interpreting water-body margins from aerial or satellite imagery, it wasn’t economically feasible for AEP to collect its own three-dimensional data on bathymetry (the underwater contours of a lake). Bathymetric data, however, were an essential component of determining the morphometrics of the hundreds of other lakes in the region. 

AEP commissioned Barr to come up with a way of filling in the missing bathymetric piece. The agency gave us two objectives: to identify, collect, and organize existing bathymetric data AEP didn’t already have access to, and to develop a strategy document for ongoing collection and management of morphometric data.

To help the agency quickly identify possible sources of — and then obtain — bathymetric data, Barr facilitated a workshop with potential data holders at other provincial and federal agencies and organizations, including universities and the North Saskatchewan Watershed Alliance. The workshop turned up not only records at those institutions but unpublished information at AEP itself. In addition, the event allowed us to gain an understanding of local challenges and to recognize opportunities for further data collection.

To allow AEP to manage raw and processed morphometric data and transfer the information to its digital assessment tools, Barr designed a database to house the files and the GIS data being gathered. We also developed a strategy document that (1) detailed parameters for prioritizing the collection of morphometric data for lakes in the North Saskatchewan region and (2) recommended economical and logistically practical methods of collecting the data.

The document also included a scoring system that could be used in prioritizing lakes, choosing data-collection technologies, assigning agency staff members to collect data, and storing and analyzing the information.

The Twin Cities experienced record snowfall in late winter 2019. With cold temperatures helping to maintain the snowpack, Barr regularly estimated the snowpack’s water equivalent to determine if and when the Valley Branch Watershed District should implement emergency drawdown procedures for its flood-prone lakes in the northwest portion of the watershed. Six outlets on the lakes and other water bodies include adjustable weirs so that the district can lower lake levels under certain conditions.

In mid-March, Barr measured an average of four inches of water equivalent in the snowpack, triggering emergency drawdown procedures. We notified property owners and coordinated with the Minnesota Department of Natural Resources to gain access to the outlets. With Barr’s direction, the district’s contractor then began removing stop logs, monitoring water elevations, and replacing stop logs at all six outlets and associated water bodies. We provided construction oversight and continued to monitor the snowpack’s water equivalent.

During the 12-day emergency drawdown, the district created an additional storage volume of nearly 600 acre-feet in the water bodies by lowering the outlets—enabling the system to store and convey snowmelt and rain runoff with a reduced flood risk to adjacent property owners. While flooding affected infrastructure and homes in other Twin Cities areas, no significant flooding or damage to homes occurred around the Valley Branch Watershed District’s flood control system.

In 2007, not long before the Minnesota Pollution Control Agency was to approve a new NPDES permit for Brainerd Public Utilities’ wastewater-treatment-facility upgrade, an agency study detected PFOS (perfluorooctane sulfonate, a type of PFAS) in BPU’s wastewater effluent at significantly higher concentrations than were found in the effluent of other municipalities tested. 

To keep NPDES permit approval on track, MPCA staff recommended that BPU find the source. Because a pending low-interest loan for facility upgrades was tied to permit issuance, the utility had to act fast. Barr was hired to help find the source of PFOS entering BPU’s sewer system. Within 10 days, we had collected water samples, coordinated laboratory analysis, and determined the primary source: an automotive-chrome refinishing facility. 

We then met with the MPCA, BPU, and city staff to discuss probable NPDES-permit effluent limits for the reach of the Mississippi River to which BPU’s facility discharges. With Barr’s negotiating assistance, BPU was able to establish limits for PFOS that both met the agency’s stringent standards and were achievable for the utility. 

After the permit was issued, Barr worked closely with BPU’s legal counsel to preclude a lawsuit from an environmental group.

For over two decades, Barr has been providing engineering services at Xcel Energy’s Cedar Falls hydroelectric dam on the Red Cedar River. The mostly hollow Ambursen dam was constructed in 1910 and creates the 1,800-acre Tainter Lake located on the river. The dam, which is classified as high hazard, is about 60 feet tall, has an overflow spillway roughly 250 feet in length, and has a gated spillway with two small tainter gates.

Because the project was incapable of passing the current inflow design flood (IDF) prior to overtopping, Xcel hired Barr to conduct an initial study to compare options to safely pass the IDF. The option selected consisted of a new ogee spillway with six large tainter gates and a smaller crest gate to pass debris and lower return-period flows.

Barr worked with the St. Anthony Falls Laboratory at the University of Minnesota to construct a 1:36 scale physical model of the entire structure, including the proposed spillway replacement and stilling basin. The physical model confirmed the modified spillway’s ability to pass the IDF as well as the stilling basin’s function to contain the hydraulic jump for a range of flow conditions. It also helped to understand preferred gate operations as well as model water control during stages of the planned construction. Additionally, the physical model was used to test optimized stilling basin designs, which allowed the overall basin length and construction cost to be reduced.

Final design was completed in July 2020 and included the new spillway, stilling basin, and gates. Phased construction activities for the spillway modifications are currently in progress.