The new Bozeman Public Safety Center has been constructed at the site of the former MDT yard facility, located on the southwest corner of N. Rouse Avenue and W. Oak Street on the northeast side of Bozeman. This 8-acre site development includes a large, multi-story building and several asphalt parking lots and roadways. The building houses the police department, the municipal court facilities, and one of the City’s fire stations.

AESI first became involved with the project in 2014 during the initial concept phase. At that time, we were retained for a preliminary geotechnical investigation and report of the subject property. In 2019, as the project design progressed, we performed additional field explorations to better characterize the site conditions. This was followed by the preparation of the final geotechnical report for design and construction.

The two biggest findings of the geotechnical work were that the site was blanketed by a 1.5 to 2.0-foot layer of asphalt millings/roadmix gravel and that the “target” bearing material for the building was the native sandy gravel at a depth of generally 5.0 to 7.0 feet. To save a substantial amount of money, we recommended stripping/salvaging all of the existing asphalt-laden gravel materials from the surface of the site and re-using these materials as part of the sub-base gravel section under new asphalt areas. This saved on both the haul-off of the material and the importing of all new gravel. Due to the footprint size of the building and the number of interior footings, we recognized that traditional footing over-excavation/replacement down to the “target” native gravel would be impractical and uneconomical. Instead of standard foundation earthwork, we recommended a ground improvement system consisting of rammed aggregate piers under all foundation elements (including perimeter, interior, and exterior footings). This foundation system was chosen and designed to include over 650, 30-inch piers that extended down into the “target” native gravel.

AESI has been involved with the site and foundation construction since it began in the spring of 2020. We observed the stripping/salvaging of the asphalt-laden gravel materials, the preparation of subgrade, and the placement of the sub-base gravel sections under new asphalt areas. In the building area, we monitored the construction of the gravel building pad, provided QA inspection/oversight during the installation of the rammed aggregate piers, and observed the foundation excavation and the exposed tops of the piers under footing locations.

Site Conditions: The site was covered by a 1.5 to 2.0-foot layer of asphalt millings/roadmix gravel, which required careful management to reuse these materials effectively and economically.

Foundation Design: The native sandy gravel, identified as the “target” bearing material, was located at a depth of 5.0 to 7.0 feet. Traditional footing over-excavation and replacement were impractical and uneconomical due to the building’s footprint and the number of interior footings.

Ground Improvement: Implementing a ground improvement system with over 650 rammed aggregate piers was a significant undertaking. This required precise installation and quality assurance to ensure the stability and integrity of the foundation.

Material Management: Stripping and salvaging the existing asphalt-laden gravel materials and reusing them as part of the sub-base gravel section under new asphalt areas required meticulous planning and execution to save costs and reduce waste.

Coordination and Oversight: Continuous involvement from AESI for site and foundation construction, including monitoring subgrade preparation, gravel building pad construction, and the installation of rammed aggregate piers, was essential to address any issues promptly and maintain project timelines.

Reuse of Existing Materials: Stripped and salvaged the existing asphalt-laden gravel materials from the site and reused them as part of the sub-base gravel section under new asphalt areas. This approach saved on both the cost of hauling off the material and the expense of importing new gravel, making the project more economical.

Ground Improvement System: Instead of traditional footing over-excavation, a ground improvement system using rammed aggregate piers was implemented under all foundation elements. This method provided a stable foundation for the building, with over 650, 30-inch piers extending into the native sandy gravel, ensuring the structural integrity of the building.

Cost Savings: The reuse of existing materials and the innovative foundation solution significantly reduced project costs.

Structural Integrity: The ground improvement system ensured a stable and durable foundation, capable of supporting the large, multi-story building.

Efficient Project Execution: Continuous monitoring and quality assurance helped maintain project timelines and addressed any issues promptly, leading to a smooth construction process.

AESI, in collaboration with Western EcoSystems Technology, conducted wetland delineations and rare plant surveys across six sites in Yellowstone National Park for the National Park Service. Spanning approximately 230 acres, these surveys aimed to identify sensitive environmental areas to guide heavy equipment placement for future fuel treatment projects. AESI utilized sub-meter GPS technology to record wetland boundaries, captured site photographs, and integrated data onto geo-referenced aerial imagery and U.S. Geological Survey maps. Additionally, field teams mapped ordinary high water marks for stream channels and water bodies within the project areas. The final reports provided detailed classifications of palustrine emergent and palustrine forested wetlands, including key vegetation and hydrology characteristics essential for boundary determinations.

The project faced a tight timeline, as the contract was awarded in mid-August, leaving limited time to plan and complete the field surveys within the short growing season. This constraint required rapid mobilization and efficient execution to ensure accurate data collection before seasonal changes impacted plant identification and wetland assessments.

AESI quickly developed a comprehensive field survey plan, streamlining methods, sampling protocols, and safety measures to maximize efficiency. Field teams worked within the constrained timeframe to collect high-quality data, ensuring thorough documentation of wetland boundaries and rare plant locations. The final reports provided the National Park Service with precise maps and detailed environmental assessments, supporting informed decision-making for future land management and conservation efforts.

Powell Dam, an embankment dam located on the Montana Correctional Enterprises (MCE) Ranch, is classified as a high-hazard structure with a normal storage volume of 200 acre-feet. Due to its steep embankment slopes, high uncontrolled seepage rates, and past stability concerns, rehabilitation was necessary to ensure long-term safety and functionality.

AESI conducted detailed five-year engineering inspections of Powell Dam in 2014, 2019, and 2024, identifying key deficiencies that informed the rehabilitation design. Our team also assisted MCE in securing funding by preparing applications for DNRC Renewable Resources grants and FEMA High Hazard Potential Dam (HHPD) grants. The project required close collaboration with MCE, DNRC, and Montana Disaster & Emergency Services to navigate regulatory requirements and funding processes.

Key project tasks included a site visit, topographic survey, dam breach and inundation modeling, spillway capacity analysis, slope stability assessments, and embankment rehabilitation design. AESI compiled these findings into a comprehensive design report, outlining solutions to enhance the dam’s structural integrity and mitigate potential risks.

The project was phased to align with funding availability, requiring careful planning to match grant cycles and budget constraints. Additionally, to meet cost-share requirements and reduce overall construction expenses, select construction tasks were assigned to MCE Ranch’s Job Corps labor program, necessitating coordination between engineers, contractors, and workforce trainees.

AESI’s efforts have successfully secured two DNRC grants and one FEMA HHPD grant, with an additional construction-phase HHPD grant pending award. The rehabilitation design is now complete, and construction will commence once full funding is secured. By strategically phasing the project and leveraging available resources, AESI helped ensure a cost-effective and well-planned path toward improving Powell Dam’s safety and reliability.

In the summer of 2019, AESI provided geotechnical engineering and construction support services for the renovation of the historic Romney Hall gymnasium at Montana State University. As part of the foundation design process, AESI observed initial helical pier load testing to verify performance under site-specific conditions. Our team conducted laboratory testing to assess the reusability of native foundation soils and monitored the placement of the first phase of production helical piers. Throughout the project, AESI oversaw the successful installation of nearly 100 helical piers, ensuring the foundation system met engineering and structural requirements for the building’s modernization.

The renovation of Romney Hall presented several challenges, including the complexity of foundation design and the installation of helical piers in variable soil conditions. Environmental factors and soil inconsistencies required adaptive engineering solutions to ensure stability and load-bearing capacity. Scheduling and budget constraints added another layer of complexity, requiring efficient coordination between engineering teams and contractors. Additionally, the project required balancing historic preservation goals with modern engineering standards to enhance the building’s structural integrity while maintaining its historical significance.

AESI provided a comprehensive geotechnical assessment to inform foundation design and optimize soil reuse. Our oversight of helical pier installation ensured precision placement and structural reliability despite variable subsurface conditions. By implementing efficient testing, monitoring, and adaptive engineering strategies, AESI helped strengthen the foundation system, extending the lifespan of Romney Hall and preserving an important historic structure for future generations.

AESI conducted hydraulic analysis and floodplain mapping for the Milk River and selected tributaries in Phillips County, Montana, as part of a comprehensive floodplain study led by MT DNRC in collaboration with FEMA and FEMA contractors. The study was designed to comply with federal and state standards and will serve as the foundation for the county’s Flood Insurance Study and updated Flood Insurance Rate Maps.

DNRC divided the project into 23 modeling domains, assigning AESI responsibility for Domains 8-14. Using 2D hydraulic modeling in HEC-RAS and floodplain mapping in ArcMap, AESI played a key role in advancing flood risk assessment methodologies. As one of the first firms in Montana to implement 2D floodway modeling, AESI’s analysis allowed for more precise mapping of complex flow patterns in flat and sinuous terrain, incorporating irrigation infrastructure and non-levee features that influence floodwater movement.

The study required detailed hydraulic modeling, particularly in Domain 11, which encompassed the town of Malta and demanded the highest level of precision in Phillips County. Additionally, the presence of Dodson Dam added complexity to flow modeling and flood risk assessment. Ice jam formation along the Milk River presented another challenge, requiring specialized analysis to account for seasonal flood risks.

AESI successfully completed one of the first 2D floodway modeling projects in Montana, enhancing the accuracy of flood risk assessment in the region. By leveraging advanced hydraulic modeling techniques, AESI provided a more detailed and realistic representation of flood behavior, improving floodplain delineations and risk mapping. These results will contribute to better-informed flood management decisions and updated regulatory tools for Phillips County.

AESI was contracted by the U.S. Forest Service (USFS) Region 1 to develop Emergency Action Plans (EAPs) for four high-hazard dams located in Montana, North Dakota, and South Dakota. The project included comprehensive dam break evaluations following USFS and Bureau of Reclamation guidelines, utilizing HEC-RAS 2D modeling to simulate inundation scenarios from dam failures. AESI created detailed inundation maps using ArcMap for both “sunny day” failures and Probable Maximum Flood (PMF) breach scenarios.

In addition to preparing the EAPs, AESI facilitated dam safety exercises involving USFS personnel, emergency management agencies, state transportation departments, and the National Weather Service. These exercises tested response protocols and provided critical insights for refining emergency procedures. To support ongoing dam monitoring, AESI partnered with AMCI Wireless to install automatic data loggers, enabling real-time reservoir water level tracking.

The project required extensive coordination among multiple agencies and USFS personnel across different states. Organizing dam safety exercises involved aligning schedules, ensuring participation from key stakeholders, and structuring discussions to effectively evaluate emergency response capabilities. Additionally, the development of accurate breach inundation maps required advanced hydraulic modeling to account for varying dam failure scenarios.

Through careful planning and stakeholder engagement, AESI successfully facilitated dam safety exercises that fostered productive discussions on emergency response procedures. These exercises provided agencies with a clearer understanding of their roles and responsibilities during a dam emergency. The finalized EAPs incorporate real-world feedback from these exercises, improving preparedness for potential dam failures. Additionally, the installation of automated data loggers enhances real-time monitoring capabilities, providing USFS with critical reservoir level data for ongoing dam safety management.

Allied Engineering Services, Inc. (AESI) conducted a comprehensive survey for the United States Forest Service (USFS) at Park Lake Dam in the Helena National Forest. The project involved creating a detailed basemap of the reservoir, embankment, and surrounding area using a combination of conventional GPS and Total Station methods, LiDAR drone technology, and sonar integrated with GPS. These methods were seamlessly combined to produce an accurate existing ground surface. Conventional survey techniques captured precise details of the dam embankment, LiDAR drone surveys mapped approximately 160 acres of surrounding topography, and sonar technology was used for lake bathymetry to map the lake bottom. The resulting surface model was utilized to develop stage-storage relationships, calculate lake volume, and support site grading efforts for the rehabilitation of the failing dam embankment.

Integration of Diverse Survey Methods: Combining data from conventional GPS and Total Station methods, LiDAR drone surveys, and sonar bathymetry into a seamless and accurate surface model required careful alignment and advanced processing techniques.

Data-Intensive Analysis: The project generated a significant volume of data from multiple survey methods, necessitating robust computational resources and meticulous analysis to ensure precision in the final deliverables.

Detailing Complex Terrain: Capturing accurate details of the dam embankment, lake bottom, and surrounding topography presented unique challenges due to varied terrains and features requiring specialized survey techniques.

Environmental and Site Accessibility: Operating in a remote forested area with natural obstacles and potential weather-related disruptions made survey operations and equipment deployment more challenging.

High-Accuracy Requirements: The project’s critical purpose—supporting stage-storage analysis, lake volume calculations, and site grading for a failing dam—demanded an exceptionally high level of precision across all survey data and final surface models.

Effective Integration of Survey Techniques: AESI successfully combined data from conventional GPS and Total Station surveys, LiDAR drone mapping, and sonar bathymetry into a single, accurate surface model. This ensured a seamless representation of the dam embankment, lake bottom, and surrounding topography.

Advanced Data Processing: By implementing robust data processing workflows and leveraging high-capacity computational resources, AESI managed the large volume of data efficiently. This produced reliable and precise outputs necessary for the project’s success.

Accurate Mapping Across Varied Terrain: AESI utilized conventional survey methods for capturing fine details of the dam embankment, LiDAR technology to map the expansive 160-acre area, and sonar to provide a complete picture of the lake bottom. This comprehensive approach resulted in a detailed and accurate representation of all critical project features.

Adapting to Remote and Challenging Conditions: Despite the remote forested location and natural obstacles, AESI adapted equipment deployment and workflows to complete the surveys effectively. This ensured the project was delivered on time without compromising accuracy or quality.

Delivering a Comprehensive Ground Surface for Analysis: The final surface model, which incorporated all surveyed elements, supported detailed stage-storage analysis, lake volume calculations, and site grading for the failing dam. This comprehensive deliverable was instrumental in facilitating the rehabilitation planning for Park Lake Dam.

AESI was contracted by Montana State University (MSU) to update their Water Facility Plan. The MSU campus is quickly expanding in both the number of buildings and the number of students/faculty, so planning for the maintenance and upgrades of the water distribution system is an important task. AESI’s engineers utilized Bentley’s WaterCAD computer software to model the existing MSU water distribution system and identify any current issues, which included fire hydrants being unable to deliver the needed fire flow, low system pressures, high velocities in pipes, major system leaks, and areas not receiving sufficient supply. Once any problems with the existing system were identified, scenarios were created in the computer model to analyze the potential solution. AESI engineers then recommended the best solutions for each issue to MSU. Lastly, AESI developed model scenarios based on likely future development within the campus. Campus populations and water usage trends were analyzed in detail to build these scenarios. Future development scenarios analyzed the feasibility of delivering sufficient water supply to new buildings and a continuously growing campus population while still meeting regulatory requirements of minimum/maximum system pressures, system velocities, and fire flow.

The MSU Water Facility Plan Update required intimate knowledge of pressurized water networks and computer-based modeling. It also relied heavily on excellent data management. The project’s greatest challenge was creating and calibrating an accurate model of the MSU water system. This challenge was overcome by isolating the MSU system from the City of Bozeman’s water system. By isolating the private water system from the public network, AESI was able to calibrate the model nearly perfectly to match real hydrant tests and simulate day-to-day conditions, providing confidence that proposed scenarios would be reliable. AESI’s wealth of knowledge with water systems and how to model them made this project a success.

The MSU Water Facility Plan Update project presented several challenges that required a combination of technical expertise, innovative problem-solving, and meticulous data management. One of the most significant challenges stemmed from the rapidly expanding MSU campus, which placed increasing demands on the water distribution system. This growth introduced numerous issues, including fire hydrants unable to deliver sufficient fire flow, low system pressures, high pipe velocities, major system leaks, and areas experiencing inadequate water supply. Identifying and addressing these complex issues within an interconnected system required a precise and comprehensive approach.

Another major challenge was developing an accurate and calibrated model of the MSU water system. The task was complicated by the need to isolate the university’s private water network from the City of Bozeman’s public water system, as any overlap could distort the model’s accuracy. Ensuring the model aligned with real-world conditions, such as hydrant flow tests and daily water usage patterns, was critical to building confidence in the reliability of proposed solutions.

Planning for future campus development added another layer of complexity. The project required detailed analysis of population growth, water usage trends, and campus expansion scenarios to predict whether the system could meet future demands. These predictions had to account for regulatory requirements, such as maintaining minimum and maximum pressures, controlling system velocities, and ensuring adequate fire flow for new developments, all while accommodating a continuously growing population and infrastructure.

To tackle the challenges of the MSU Water Facility Plan Update, AESI used Bentley’s WaterCAD software to model the university’s water system, identifying key issues like inadequate fire flow, low pressures, high velocities, leaks, and insufficient supply. By isolating MSU’s private water network from the City of Bozeman’s system, AESI calibrated an accurate model, ensuring reliable solutions.

The team proposed targeted upgrades to resolve current issues and developed future scenarios based on campus growth projections. These scenarios ensured regulatory compliance for pressures, velocities, and fire flow, providing MSU with a comprehensive, adaptable plan for its expanding water system.

As part of their IDIQ contract with the USFS Region One, Allied Engineering provided engineering and surveying services for the repair of the Sullivan Bridge gabion abutment on the north side of the east abutment of the bridge.

Sullivan Bridge is located on National Forest System Road 895 in a remote area on Hungry Horse Reservoir. An initial site visit was conducted in July 2016 by Allied Engineering and the US Forest Service. Following the field visit, it was decided that the failing gabions should be removed, the slope re-shaped and protected to minimize erosion and channelization, and an engineered toe should be built and backfilled with riprap up to the existing road shoulder. All survey, evaluation, and construction needed to consider steep slopes and cliffs inaccessible to most equipment.

The site was surveyed with a combination of high-definition scanning, bathymetric surveys with GPS integrated depth finder, and conventional survey and GPS. Several different design and construction options including barge access, long reach excavators, and specialty drilling and anchoring equipment, and techniques were then considered and discussed by Allied Engineering and the Forest Service. The preferred alternative included removing the existing gabion baskets entirely and replacing them with a stacked riprap fill slope. Because the catch point is a thin section of steep bedrock, the toe of the riprap is supported by gabion reno mattresses anchored into the rock with driven rebar pins. These pins and mattresses help to buttress the bottom of the riprap slope along with providing some vertical clearance between the bottom of the rock and the existing bedrock catch point. Construction documents were developed in September 2016 including plans, engineer’s opinion of probable construction cost, supplemental specifications, and schedule of items. A report was also prepared to summarize the design process and describe how and why the final design was chosen.

Remote Location Access: Sullivan Bridge is located in a remote area on Hungry Horse Reservoir, making access challenging. Transporting personnel, equipment, and materials to such an isolated site would require careful logistical planning, potentially increasing costs and project duration.

Steep Slopes and Inaccessible Terrain: The project area included steep slopes and cliffs that were largely inaccessible to standard construction equipment. Working on these slopes required specialized surveying and construction techniques and equipment, adding complexity to the planning and execution.

Erosion and Slope Stability: The site’s steep and unstable slopes posed a risk of erosion and channelization, particularly after removing the failing gabions. The team had to carefully re-shape and reinforce the slope to prevent future erosion and maintain long-term stability, which required precise engineering and innovative solutions.

Technical Survey Requirements: The combination of high-definition scanning, bathymetric surveys, GPS, and conventional survey techniques presented technical challenges. Integrating and analyzing data from different survey methods required advanced expertise and coordination to ensure accuracy.

Limited Equipment Options: Due to the site’s inaccessibility, traditional construction equipment was unsuitable. The team had to consider alternative approaches, such as barge access, long-reach excavators, and specialty drilling and anchoring equipment, requiring significant planning and potentially high equipment rental costs.

Anchoring in Bedrock: The design required that the toe of the riprap slope be anchored into steep bedrock using gabion reno mattresses and rebar pins. Anchoring into thin, steep bedrock presents challenges with securing materials effectively, requiring precise drilling and reinforcement to ensure stability.

Environmental Protection: Working near a reservoir necessitated additional precautions to protect water quality and surrounding habitats. Implementing these environmental safeguards while conducting construction on steep and fragile slopes would add another layer of complexity to the project.

Design Complexity and Safety: The unique challenges of the site required careful design considerations and coordination between Allied Engineering and the US Forest Service. Safety for workers on steep slopes, handling heavy materials, and dealing with specialized anchoring and drilling techniques added risk that required stringent safety protocols and oversight.

Development of Comprehensive Construction Documents: Given the site’s complexities and remote nature, developing thorough construction documents, specifications, cost estimates, and schedules would be essential to mitigate the high risks and unpredictability associated with this project.

Comprehensive Site Surveying: Allied Engineering used a combination of high-definition scanning, bathymetric surveys with GPS-integrated depth finders, and conventional surveying methods to accurately map the complex terrain. This multifaceted approach ensured precise data collection, which was essential for creating a tailored engineering solution.

Specialized Equipment for Inaccessible Terrain: The project team considered various options to overcome the remote, steep terrain, including barge access and long-reach excavators. Ultimately, they opted for specialty drilling and anchoring equipment that allowed work on steep slopes and difficult-to-reach areas, improving safety and effectiveness in the challenging environment.

Re-shaping and Stabilizing the Slope: To address erosion and slope instability, Allied Engineering reshaped the slope and protected it with an engineered toe structure backfilled with riprap. This reinforced slope reduced erosion risk and prevented future channelization, providing long-term stability for the bridge’s foundation.

Anchoring with Gabion Reno Mattresses and Rebar Pins: The design called for removing the failing gabions and constructing a stacked riprap slope, reinforced at the base with gabion reno mattresses. These mattresses were anchored into the steep bedrock using driven rebar pins, which provided a stable foundation and prevented slope movement along the bedrock’s edge.

Collaborative Design Process: Allied Engineering worked closely with the US Forest Service to explore various design options, ensuring the chosen solution met safety, budgetary, and environmental considerations. This collaborative approach allowed the team to select the best possible alternative given the project’s unique constraints.

Improved Structural Stability: The re-shaped slope with stacked riprap and anchored gabion mattresses provided a stable, resilient foundation for the bridge, protecting it from erosion and future deterioration.

Extended Service Life of the Bridge: The reinforced abutment and stable slope foundation significantly enhanced the longevity of Sullivan Bridge, ensuring it can withstand environmental pressures and serve the public for years to come.

Enhanced Safety and Accessibility: By stabilizing the slope and creating a secure foundation, the project improved the overall safety and accessibility of National Forest System Road 895, benefitting those who rely on this remote route.

Environmental Protection: The engineered slope and riprap design minimized erosion and preserved the surrounding natural landscape, helping to protect the reservoir and local ecosystem from sedimentation and potential contamination.

Rabbit Creek Dam, a zoned earthfill structure southwest of Reva, South Dakota, serves as both a water retention facility and a roadway embankment for Highway 79. AESI was contracted by USFS Region 1 to conduct a comprehensive safety inspection, hazard analysis, and geotechnical investigation to assess the dam’s stability and risk profile.

The project included a full Potential Failure Mode Analysis (PFMA), a risk-based geotechnical assessment, and detailed stability modeling of the embankment. AESI evaluated seismic hazard and liquefaction potential, conducted an overtopping hydraulic scour study, and used advanced numerical modeling tools such as SLOPE/W for stability analysis and SEEP/W for seepage analysis. Additionally, drone survey data helped identify potential weak points, including low areas and possible sinkholes.

A key focus of the hazard analysis was reassessing the dam’s classification, which had previously been designated as Significant Hazard. However, prior evaluations had not accounted for the fact that Highway 79 runs along the embankment, posing a direct threat to motorists in the event of failure. Based on AESI’s findings, the classification was recommended for an upgrade from Significant to High Hazard. Following this assessment, AESI was contracted to conduct a feasibility study for dam decommissioning and later to develop a design for the selected decommissioning alternative.

The hazard analysis required a detailed evaluation of complex failure modes, necessitating extensive numerical modeling to simulate different risk scenarios. Advanced tools such as HEC-HMS, SLOPE/W, and SEEP/W were used to analyze hydrologic and geotechnical conditions. Accurately assessing the dam’s failure impacts and potential life-safety risks demanded close coordination with USFS and a thorough review of all available data.

AESI’s comprehensive analysis led to the hazard classification being raised to High, in part due to the increased risk to motorists on Highway 79. This reclassification informed USFS decision-making, ultimately leading to the selection of dam decommissioning as the preferred course of action. AESI’s subsequent work on the feasibility study and decommissioning design ensured that the project moved forward with a well-documented and technically sound approach, prioritizing public safety and long-term site stability.

AESI conducted a comprehensive infrastructure risk assessment for 17 large culverts and tunnels beneath earthen railroad embankments along the Route of the Olympian in Mineral County, Montana. These culverts, originally constructed over 100 years ago by the now-defunct Milwaukee Road Railroad, had not been maintained for more than 50 years, presenting significant structural and hydraulic risks. The purpose of the study was to evaluate geotechnical and hydrologic failure risks and prioritize necessary repairs.

The project involved advanced geotechnical explorations, drone aerial surveys, hydrologic and hydraulic modeling, and slope stability design. AESI utilized Monte-Carlo simulations and numerical modeling to develop a “reliability index” ranking from 0 to 1 for each culvert, providing a data-driven approach to risk assessment. A UAV drone was used to gather 3D topographic survey data in remote areas, while software tools such as Slope/W and HY-8 helped assess the geotechnical and hydraulic reliability of each structure. The final Geotechnical Investigation Report outlined repair prioritization strategies and detailed various rehabilitation options, ranging from cleaning and lining to full replacement using micro-tunneling techniques.

The project presented unique challenges due to the age and deteriorated condition of the culverts, the lack of prior maintenance records, and the complexity of assessing massive earthen embankments. Additionally, the remote location and varying terrain required innovative survey and modeling approaches to accurately evaluate structural integrity and failure risks.

AESI’s analysis provided a clear and systematic approach to culvert remediation planning. The final report delivered prioritized repair recommendations based on geotechnical, hydraulic, and structural risks, giving USFS Region 1 a valuable tool for phased infrastructure improvements. By integrating advanced modeling techniques and risk-based evaluations, AESI ensured that repair efforts would be strategically targeted to maximize safety and cost-effectiveness.

“[AESI] professionally provided insightful, effective, and efficient engineering innovations that achieved or exceeded all needs and expectations. The product of this effort is a report with clear narrative, colored tables, and graphic displays that is immediately a very constructive tool for managers to being remediation planning.” – Traci Sylte, USFS

In 2010, a soil nail and shotcrete wall was constructed to stabilize a landslide in Hyalite Canyon. Since 2012, the USFS has actively monitored this wall for any movement. AESI was engaged to conduct annual slope inclinometer readings from two devices located on the bench in front of the wall. In 2018, AESI submitted a report analyzing ongoing issues at the slide, noting an acceleration in slope movement. To address this, AESI was tasked with laying out proposed horizontal drains, designing the access road, installing additional slope inclinometers and piezometers, and assisting with the selection and acquisition of remote monitoring equipment. AESI also monitored and surveyed the horizontal drains, developed AutoCAD Civil 3D soil horizon models using drone survey data and borehole logs, and back-calculated initial slope failure parameters using SLOPE/W. They then drafted a current-state SLOPE/W stability model with soil nail parameters estimated from third-party documentation.

Monitoring & Data Collection: Continuously monitoring the soil nail and shotcrete wall for movement required precise and consistent data collection over several years.

Accelerating Slope Movement: The slope movement appeared to be accelerating, which posed a significant risk to the stability of the wall and surrounding area.

Design and Installation of Horizontal Drains: Designing and installing horizontal drains in challenging terrain required careful planning and execution.

Developing Accurate Models: Creating accurate soil horizon models and stability models required integrating various data sources, including drone surveys and borehole logs.

Coordination and Communication: Coordinating with multiple stakeholders, including the USFS and third-party documentation providers, was essential for the project’s success.

Monitoring & Data Collection: AESI conducted annual slope inclinometer readings and installed additional monitoring equipment, such as piezometers and remote monitoring devices, to gather accurate data. The implementation of slope inclinometers, piezometers, and remote monitoring equipment provided continuous and accurate data on slope movement. This allowed for timely interventions and adjustments as needed.

Enhanced Stability: AESI analyzed the data and proposed the installation of horizontal drains to manage groundwater and reduce slope movement. The installation of the soil nail and shotcrete wall, along with the horizontal drains, significantly improved the stability of the landslide area. This reduced the risk of further movement and potential damage.

Design and Installation of Horizontal Drains: AESI laid out the proposed drains, designed the access road, and monitored the installation process to ensure effectiveness.

Developing Accurate Models: AESI used AutoCAD Civil 3D and SLOPE/W software to develop detailed models and back-calculate initial slope failure parameters, ensuring a comprehensive understanding of the site conditions.

Coordination and Communication: AESI maintained clear communication and collaboration with all parties involved, ensuring that the project stayed on track and met all requirements.

Cost Savings: By using advanced modeling techniques and precise data analysis, AESI was able to design effective solutions that minimized unnecessary expenditures and optimized resource use.