Schnabel University 2020

Table of Contents


Abstracts and Bios

Links and Downloads

Abstracts


Embracing Risk—Friday Sessions

Johanna Simon, Todd Roberts (Sensemetrics)

Automate Your Measurements with IMS

​Have you worked on a project that has an instrumentation specification and wondered what it’s all about? Schnabel’s Infrastructure Monitoring System (IMS) powered by sensemetrics is a customizable data collection and visualization platform that allows us to collect near-real time data that is accessible to us and our clients 24-7. This monitoring system can be used for temporary monitoring during a construction project as well as long term monitoring. Don’t waste your project budget paying someone to drive to a site to manually collect instrument readings, automate with IMS.

This presentation will demonstrate the monitoring abilities that Schnabel has in-house through recent monitoring case histories including support of excavation performance monitoring during a sewer improvement project, construction monitoring and subsequent long term monitoring of the Yeager Airport Runway 5 stabilization project, and more. Come see how IMS is rising to the occasion to meet the increasing data visualization requirements of our projects. This near real-time data monitoring paired with Schnabel’s engineering experience gives owners the upper hand in making informed decisions regarding their assets and advances our risk management ability to be proactive rather than reactive.

Glen Frank, Matt Koziol, Federico Maltese (SWS)

The Use of Digitalization and Analysis of “Big Data” for Risk Optimization

The tunnel market is currently growing at the rate of 5-7% per year, resulting in more projects being required in marginal locations. Many projects are now located in unstable ground, heavily urbanized environment (often both) or in faulted rock with high overburden pressures.

Using our Digital Project technique we are able to create a three-dimensional digital twin of the existing subsurface and surface conditions, which can be used to provide valuable information concerning the risk associated with multiple potential construction methods. This model is first created through the digitalization of all of the existing relevant information relative to the site and then “”stressed”” by digitally building the tunnel multiple times, utilizing the various tunneling machine and technique options that might be considered applicable, revealing the risks associated with each. This technique utilizes BIM and GIS technologies as well as a Monte Carlo approach to address the uncertainty associated with the input data associated with the digital twin project model. The technique is particularly valuable when used in a design-build project as it allows for multiple modifications of the design geometry and materials, all of which can be subjected to multiple construction methodologies as well as multiple parameters associated with each methodology.

Mitch Youmans, Mike Senior

Boundary Dam Rock Slope Stabilization—Using Real-Time 3D Modeling During Construction to Make Field Changes and Assess Risk on a Limited Access/Tight Tolerance Project

A geologic assessment of the right abutment of Boundary Dam (located in Metaline, WA) was completed in May 2017. The stability analyses identified a potential failure plane for a rock block that supports a bridge deck abutment on the downstream face of the dam. The rock block is approximately 100 ft tall. The bridge provides access to the downstream side of the dam, and, if failure occurred, the bridge or abutment could potentially impact one of the dam’s sluice gates. Access restrictions were immediately put into place by the owner to eliminate equipment loading on the bridge deck.

Design of a long term stabilization solution was developed to restore bridge deck access. To achieve this solution, a two phased construction approach was implemented to reduce risk of failure from construction, provide safer access to the construction crew, and to restore service of the bridge. The first construction phase provided initial stabilization of the rock slope utilizing mesh and tensioned cable lashings installed by rope access and aimed to minimize disturbance to the failure plane while increasing the existing factor of safety. The second phase of construction consisted of 24 post-tensioned tieback anchors, again installed by rope access and drilled through the failure plane. The tiebacks were installed in groups based on stabilization effect and site access to incrementally ease the bridge weight restrictions throughout construction.

A unique aspect of the construction was the contractor’s means and methods and the role they played on very tight drill angle tolerances. A 3-D model, developed during the design phase, was used frequently during construction to model the as-drilled conditions and compare with the remaining proposed anchors to reduce risk during drilling, make design changes based on field observations, and to incrementally assess rock slope stability Factors of Safety. This presentation will present the design and construction of the long-term post-tensioned tiebacks. This project serves as a great example: of how the Geostructural Engineering Group can assist the Dams Group across business units and multiple offices; of supporting new opportunities and overcoming engineering challenges as we expand west; of using new 3-D model technology to make design changes in the field on a tight access job.

Stability analysis of the right abutment of Boundary Dam (located in Metaline, WA) identified the potential for instability of rock supporting a bridge abutment on the downstream face of the dam. Schnabel Engineering designed a long term stabilization solution, and post-tensions tieback anchors were installed during 2019. Because of strict access limitations and tight tolerances, the construction documents allowed for the contractor to relocate anchors in the field with engineer approval. An irregular rock face, tight spacing of anchors, a bear cave within the rock, tight tolerances, and limited cell reception made approval of field changes particularly challenging. Therefore, Dynamo scripts linking as-designed, RFI proposed, and as-installed data to a 3D BIM (Revit) model were created. This system allowed for near real-time updating of the linked 3D model and stability analysis based on the contractor’s field data and RFIs, which reduced the response to RFIs from a few days to a few hours. Results of the revised analysis were depicted as revised factors of safety, updated survey coordinates, and compact 3D PDFs, which were easily shared with the design team and field staff (even with poor cell reception). This workflow and automated model nearly eliminated manual editing of the 3D model, accelerating the RFI response time and reducing the potential for errors and company risk. Here, we present example analyses performed with Revit/Dynamo and lessons learned supporting a complicated rock stabilization construction.

James Parkes

Lessons Learned from a Catastrophic Dike Failure

​In March 2000, an 11 km long containment dike with a maximum height of 14 m suffered a catastrophic failure. The failure event resulted in the complete loss of 2.3 km of embankment and foundation materials. The dike was part of a larger containment system that the design firm had been involved with for over 15 years. The project included in-situ and laboratory testing, a design consistent with previous experience, and a staged construction approach with instrumentation and monitoring. Yet despite these measures, the dike failed dramatically and without warning. A forensic review of the design and construction records of the dike was performed to determine the cause of failure. The lessons learned from this forensic analysis include considerations related to linear projects, assessments of field and laboratory testing data, assessments of field monitoring data, evaluation of factors of safety and perception of risk, engineering judgment, and client relations.

Laura Shearin-Feimster, Sina Khodaie

The Unique Modeling of Lake Lure Dam

Lake Lure Dam was built in 1926 to progress prosperity and attract development and recreation in western North Carolina by an entrepreneur Dr. Lucius Morse. The dam ownership was transferred to the Town of Lake Lure in 1965 and serves as the centerpiece of the community. The dam is a concrete multiple-arch buttress dam with a maximum height of about 124 feet. The dam also includes a gated concrete gravity spillway (3 large Tainter gates) and an intake tower and penstock that supply water to a hydroelectric generating station located immediately downstream of the dam. In 2019, Schnabel performed an extensive condition assessment of this very large high hazard dam. Two areas of this assessment that posed unique challenges were the watershed hydrologic analysis and the seismic component of the structural evaluation.

The watershed is a large basin of just under 100 square miles in the Appalachian Highlands. When comparing the results of real-world events to what we expected based on other basins in the region, the initial results were very different. This required calibrating with watershed data from two recent storms as well as comparisons to historic large storm events.

The dam is a multi-arch design (Ambursen Dam) with a unique geometry that uses the pressure of water to its advantage in the upstream-downstream direction resulting in a structure with a low volume of concrete. However, the cross-canyon resistance during seismic events can be unfavorable, and for the 10,000-year return event, produces a modeled factor of safety of less than 1.0. Due to limited available construction drawings and details, multiple variables such as uplift profiles and foundation interaction parameters were considered in 3D finite element modeling of Lake Lure Dam. This presentation will show the intricacies of the complexities of both hydraulic and structural modeling.

David Carpenter

Creative Application of Seismic Refraction to Evaluate Known Risk Factors: Oroville Dam and the Elizabeth Tunnel

Geophysical surveys are advantageous for both reconnaissance-level evaluations and for the evaluation of known risk factors of large, complex project sites. Typical applications of seismic refraction are to investigate mapping top-of-rock, depth to rock, and rock rippability. A more unique application includes mapping the variability of subsurface P-wave velocity to identify high and low velocity zones that may be at higher risk during engineering and construction phases of a project. Two recent case studies from challenging sites are presented: the Oroville Dam and the Elizabeth Tunnel Seismic Enhancement Project. Both cases presented demonstrate the effectiveness of a creative application of the seismic refraction technique to evaluate known risk factors.

In early 2017, headward erosion of the emergency spillway of the Oroville Dam threatened a catastrophic event and prompted the evacuation of almost 200,000 residents. Timely evaluation of the dam was pertinent in order for emergency construction repairs to occur before the next rainy season. In the subsequent weeks, geophysical methods including seismic refraction, GPR, and geophysical borehole logging were initiated across the site. Seismic refraction results were used to determine portions of the emergency spillway with rock zones vulnerable to erosion.

The Elizabeth Tunnel is an approximately 5 mile portion of the Los Angeles Aqueduct which crosses the San Andreas Fault and supplies water to nearly 4 million people. To mitigate the risk of a potential tunnel collapse during a major seismic event, an innovative seismic refraction survey was conducted in the tunnel to identify areas which may be more susceptible. Results from this one-of-a-kind survey spanned the entire length of the tunnel and revealed the San Andreas Fault Zone and other areas of poor quality rock. The findings guided the engineering mitigation decisions.


Embracing Risk—Saturday Sessions

Allen Bowers, Evan Ruggles

Integration of Risk Services within a Geotechnical Design Project

This presentation will demonstrate the successful implementation of risk analysis for a traditional geotechnical design project and discuss lessons learned. Schnabel’s scope of services for this project was to design permanent stabilization for a failing slope in Arlington, VA. The failing slope in its existing condition has a small retaining wall at the base of the slope. A building located less than 3 ft from the base of the existing retaining wall is in direct danger from a slope failure and presented significant construction access challenges. The owner engaged us to perform a geotechnical subsurface exploration, provide conceptual stabilization options, and perform the final design of the selected stabilization system. The owner preferred stabilization systems whose construction would not require building demolition, however, they asked us to consider systems that assumed a portion of the building would be demolished to allow for construction access. Though the owner only requested a cost estimate of each concept, we did not believe that cost alone was an adequate metric to differentiate the stabilization options and convey constructability challenges and risks. Thus, we presented the conceptual stabilization options within a risk framework so as to adequately convey the level of risk associated with each option in relation to possibility of cost and schedule overruns, safety, and constructability. The owner was very happy with this approach, and because of Schnabel’s risk analysis, the owner ultimately elected to demolish the building as it had the lowest risk-cost. The lessons learned from this project include a better understanding of geotechnical projects specifically suited for risk-based approaches, how to educate clients to think in a risk-based framework, and how to shed the burden of accepting risk from the engineer to the client.

Stephen Miller

Modeling Effects of Large-Diameter Tunnel on Proposed Residential Development

The Mill Creek Peaks Branch State Thomas Drainage Relief Tunnel (Mill Creek Tunnel) in Dallas, Texas will be 5 miles long, and excavated in Austin Chalk, a soft limestone, at a diameter of 33 feet. The tunnel will provide drainage relief to the upper portions of Mill Creek and Peaks Branch watersheds and the State Thomas area. Schnabel has worked on numerous tunnel projects in Texas and particularly in the Austin Chalk, the host formation for this tunnel. Schnabel also pre-bid work for a contractor whose bid was unsuccessful and was thus very familiar with project details.

A developer proposed a 5-story multi-family development with a 6-story parking garage and other amenities, on a site above a portion of the tunnel that is in a subsurface easement at a depth of 120 feet. The developer’s financing partners were concerned with the potential impact of the tunnel on the proposed residential construction. The developer requested that Schnabel/SWS perform a review of the potential impact of tunneling on their proposed complex.

The majority of the structures was to be supported on slab-on-grade with some column footings and grade beams, but the parking garage and other heavier loadings were to be supported on drilled piers to depths of 50 feet or more in the Austin Chalk. Schnabel/SWS performed numerical modeling to assess the potential displacements at foundation depth and the ground surface and their effects on the proposed facilities. This presentation will describe the ground conditions, the physical facilities, the approach to modeling the ground conditions and progress of tunneling, and the projected settlements and their probable consequences to the development.”

Seth Frank, Andrew Kolbert

A Discussion of the Merits of Continued Use of Upstream Construction

On November 5, 2015, and January 25, 2019, two high profile, (and tragic) tailings dam failures occurred in Brazil, resulting in industry-wide scrutiny. News articles question why “”we are allowing dams [with upstream construction methods] in the US that countries in the developing world do not accept,”” (Wall Street Journal article, referenced in ASDSO All-Member Community Discussion). Schnabel is the engineer of record for more than 100 coal refuse disposal (tailings) facilities in the Appalachian coal fields and the Illinois Basin. The vast majority of those incorporate some amount of upstream construction. If upstream construction is effectively banned in Canada, parts of the European Union, and a growing number of developing countries, why are we still designing and building them in the US?

We’ll briefly review findings from the publicized Fundau Tailings Dam Investigation and early indications for Brumadinho. We’ll differentiate the failed dams from those Schnabel continues to successfully design and construct. In addition to design and construction methods, greater attention is and will be focused on the downstream impact of potential failures.

Currently the federal Mine Safety and Health Administration (MSHA) only “”encourages”” preparation of Emergency Action Plans for high and significant-hazard-potential tailings dams, with several state agencies requiring them. We will discuss how incorporating GIS and modeling software (ArcMap and HEC-RAS) and mapping (LiDAR) has allowed us to continuously improve – meeting the needs of existing and potential future clients. These improvements were facilitated by inter-office collaboration, making use of Schnabel’s expertise in other industries.

Jesse Wullenwaber, Adam Paisley, Jonathan Harris

Remedial Foundation Grouting at Embankment Dams — Risky or Risk Reduction Measure?

​Remedial foundation grouting below embankment dams is a method sometimes used to reduce seepage and its associated failure modes. However, the potential risks created during remedial grouting activities may not be thoroughly considered in the dams industry. “Do no harm” is a phrase often stated when discussing doing any work in and around embankment dams. However, could performing drilling or grouting in or below dams could introduce new failure modes to the structure? The presentation will review industry practices in remedial grouting, as well as some construction and long-term risks to Dam Safety. Discussion will suggest consideration of alternative seepage control measures and will mention opinions of select federal agencies on the appropriateness of remedial grouting in and beneath embankment dams.

Michelle Bolding

Risk over the Rappahannock

​A discussion of risk for the I-95 SB Rappahannock River Project (a design-build project). A post-design, mid-construction look back on the anticipated (known) risks, the risks that were discovered, and how the risks were addressed. In general, how risk was anticipated in the DB project and the pros and cons of the risks assumed by the Team.

Jonathan Harris, Jerry Robblee, Corey Schaal

Filter Design Standards vs Risk Informed Evaluation of Existing Filters

​Standards based approaches to filter design for embankment dams are common in the dam industry. These standard methods provide a means for specifying proper filter material properties to reduce the likelihood of continued erosion of core materials in the unlikely event that a flaw exists in the dam. Standards based approaches have led to reduced occurrence of dam failures and incidents due to internal erosion. For many dams, when evaluating existing zoned embankments for filters, standards based methods may show that these materials do not strictly meet these guidelines. There are risk informed methods that can be used to inform engineers to what degree a material that may act as a filter. This presentation will provide a summary of standards based methods and describe several projects where risk informed tools were used to assess filter compatibility of existing zoning of earthen embankments. These methods provide a means for determining how likely it is that if internal erosion initiates that a filter may limit continued erosion.


Designing the Future—Friday Sessions

Arif Bhuiyan, Emily Gibson

Seismic Site-Specific Response Analysis (SSRA) and Liquefaction Analyses — Benefits and Potentials

The design of commercial structures requires the estimation of seismic loads. To assess the expected soil amplification and resulting ground motions at the surface, generic amplification factors are typically applied. These amplification factors are often overly conservative or even inaccurate. The building code allows a site-specific response analysis (SSRA) to be performed to better characterize this amplification and develop improved ground motion estimates for our clients.

Historically, Schnabel has performed SSRA when a client has requested it, but it has never been something that we openly market. Coming from S&ME, Arif has performed many SSRAs around the country and developed a methodology that will allow us to compete with the rest of the industry. Additionally, Schnabel has recently instituted a contract with Dr. Russell Green from Virginia Tech to perform senior review to ensure we’re providing high-quality results in accordance with the current state of practice.

This presentation intends to provide a concise overview of the SSRA methodologies and the required inputs and exploration needs. The presentation will also discuss when SSRA is required (i.e., liquefiable site) or it could be beneficial (i.e., cost savings) to the structural designer as per the relevant code provisions. Additionally, we’ll outline our capabilities for performing liquefaction analyses based on results of the SSRA. Studies of these seismic hazards have great potentials to participate in Schnabel’s strategic risk initiatives. Most importantly, this presentation will provide a platform for different sectors of the company to discuss their seismic needs as well as to identify technical resources within Schnabel.

Del Shannon

Improving Performance and Reducing Costs: Advances in Roller Compacted Concrete (RCC) Gravity Dam Design and Construction

Concrete dams do not fail in compression. A compressive failure would require the concrete to be crushed under large compressive loads, which is virtually impossible. Failure modes such as sliding along the foundation contact, instability due to uplift or insufficient tensile strengths to resist seismic loads are far more critical when evaluating the stability of a concrete gravity dam. Roller compacted concrete (RCC) has become the most common concrete dam construction material, and during the design process the compressive strength of the RCC is often the most evaluated, criticized and tested element of RCC gravity dam design. The unconfined compressive strength of RCC is focused on because correlations exist to estimate the compressive strength to its tensile strength and cohesion. The use of unconfined compressive strength testing to assume all concrete design parameters exists because these tests are easy and relatively inexpensive to perform, although they do not accurately identify the true direct tensile strength of the RCC. However, performing direct tensile strength testing is often difficult and expensive. Because of this, indirect split tension test (also call Brazilian tensile tests) have become a more popular, albeit less accurate and overly conservative, method to indirectly estimate RCC tensile strengths.

The tensile strength of RCC dams becomes most important during extreme loading conditions, such as earthquakes and large flood events. It is understood that RCC static tensile strengths increases under dynamic loading and the dam industry typically estimates this Dynamic Increase Factor (DIF) to be approximately 150% of the static tensile strength. However, engineers and researchers designing concrete bunkers to survive explosive forces (e.g. bombs and other explosive devices) began evaluating the ability of concrete to resist rapid loading due to explosive loads and determined that tensile strengths increase dramatically under rapidly applied loads. Through extensive testing it was determined that the DIF increased to as much as 500% to 1,000% under very high strain rates, such as those experienced during seismic events. Further, and somewhat counterintuitively, the higher tensile strengths were observed in concrete with a lower Modulus of Elasticity.

This presentation explores the importance of designing RCC gravity dams using its Modulus of Elasticity and tensile strength as the most important concrete design elements, argues for reducing the reliance of compressive strength testing to estimate the suitability of the RCC under a full range of loading conditions, and why this shift in evaluating RCC dams has the potential to increase the simplicity of the design and construction of these structure and ultimately reducing their overall cost. Areas where reduction in costs can be best achieved using this design and construction methodology include reducing the amount of cement and fly ash, less stringent gradation requirements for coarse and fine aggregates, simplifying many of the design elements and ultimately increasing the speed of construction. The author presents his experience and the experience of others designing, building and completing successful projects – projects that continue to perform exceptionally well since their completion – where these principles have been applied and significant cost savings have been achieved.

Samuel Kees, J.R. Collins

A Tale of Two Spillways: The First Two Piano Key Weirs Constructed in the United States

With the completion of construction of the Lake Peachtree Dam Replacement Project in July 2018 and the West Fork Eno Reservoir (WFER) Enlargement Project in July 2019, the first two Piano Key Weir (PKW) projects by Schnabel were complete. These were also the first two PKWs located within the United States. This presentation will look at lessons learned during the design and construction of these two projects including comparing design details that differed between the two projects and recommendations for future PKW designs.

The PKW is a variation of the labyrinth weir concept that provides unique hydraulic advantages, particularly when the available footprint dimensions are limited. The rectangular configuration of the “”keys”” provides a significant increase of weir length within a given channel width. The short base length and cantilevered apex geometry allow for even greater weir length within a relatively small footprint, making the use of PKWs convenient as a retrofit over an existing gravity section or where conventional labyrinth weirs would otherwise not be feasible due to available base length limitations.

Brent Scott, David Ebinger

High Resolution Site Characterization: The Future of Understanding Soils

High Resolution Site Characterization (HRSC) techniques use scale-appropriate measurements and sample densities to define contaminant distributions, and the subsurface characteristics in which they reside, with greater certainty, supporting faster and more effective site remediation. This innovative, versatile tooling series has both environmental and geotechnical applications with numerous state regulatory agencies and U.S. military installations recently implementing and endorsing this time saving and cost saving approach.

HRSC uses a suite of tooling including an Optical Image Profiler, a Hydraulic Profiling Tool and a Membrane Interface Probe that is advanced in the subsurface with direct push technology subcontractor. HRSC tooling can be used in conjunction with optional Cone Penetrometer Test (CPT) tooling during the evaluation of the geotechnical engineering properties of soils. Similar to CPT techniques, HRSC generates real time, in-situ data which is plotted on logs.

The on-site interpretation of the HRSC logs are used to more precisely delineate soil characteristics, groundwater elevations, and soil contamination (including LNAPL, DNAPL, VOCs, and CVOCs) and reduce uncertainty and data gaps. These data are then utilized to generate 2-dimensional (2-D) cross-sections, and/or 3-D visualizations to create a Conceptual Site Model that can be implemented from initial assessment, through remedial design, remediation and site closure.

Scarlett Kitts, Aaron Collins

Fusegate Design and Construction at North Fork Dam

​We would like to review and discuss the Fusegate spillway design and construction at North Fork Dam in Asheville, NC. This is the first time Fusegates have been used on a Schnabel designed dam. We will review and discuss the process of selecting between different alternatives, ultimate selection of the fusegates, design collaboration between offices and sub-consultants, difficulties with dealing with the Owners of the proprietary gate system, construction and the final product.​

Eric Snavely, Daniel Schultz, Nathan Young

A Case for CFD: Project Highlights from 2019

​Computational fluid dynamics (CFD) is a powerful tool that can aid in complex hydraulic calculations and simulations, especially where lower-order methods (e.g. one- or two-dimensional hydraulic models) may not capture the full three-dimensional flow behaviors present. These complex flow regimes are frequently present within the spillway rehabilitation projects that Schnabel is actively engaged with on a continuous basis. In an effort to maintain and advance this service offering to our dam clients, a small, multi-office group of water resources engineers pro-actively formed to focus collective efforts to increase the company’s capability and use of CFD. Over the past year, this internal CFD Users Group has used CFD on a variety of projects from multiple offices. The following projects will be highlighted in this presentation: estimation of hydrodynamic forces on the ogee spillway at the Carmen-Smith Hydroelectric Project; inundation analysis of a hypothetical gold tailings dam breach at Ridgeway Mine; and simulation of the probable maximum flood on the 1000-ft long spillway at Prado Dam using cloud computing. Through these project highlights, attendees will gain insight into the potential of CFD for their future projects. CFD is a critical service offering for our growing dam client base, but also provides capabilities to leverage this service offering to numerous other market segments including our growing work in the water/wastewater and hydropower sectors.​


Designing the Future—Saturday Sessions

Sara Doran, James Parkes

Converting Quarries into Reservoirs

​As more communities grow, the demand for water increases. New reservoirs are often difficult to build because of the premium costs associated with land near growing communities, as well as permitting and approval processes to site and construct new dams. A growing alternative solution to this challenge is the conversion of abandoned rock quarries into raw water storage reservoirs. Schnabel is currently providing professional services for two quarry conversion projects, the Milestone Reservoir in Leesburg, Virginia, and the Geist Reservoir in Indianapolis, Indiana. These projects involve a number of challenges including shaft and tunnel design, rock and soil slope assessments, building foundations, and design of ancillary structures. This presentation will include general considerations and benefits regarding these types of facilities and specific design considerations for these two example projects. The work on these projects highlights Schnabel’s unique ability to provide services across business units to address the design challenges associated with this emerging market.

Andrew Vasko, Kortney Brown

The Future of Design

​During the past decades many advancements have been made in how engineers and designers communicate their ideas. What once started out as handmade drawings has since transitioned to a CADD (Computer Aided Drafting Design) approach. The next evolution of this process has arrived at Schnabel! A specific sub-group of Schnabel designers has been piloting the used of BIM software (specifically Autodesk REVIT) within our project workflow. This presentation will focus on how REVIT can enhance your workflow, eliminate some sources of error, and streamline the design process. A brief overview of the design process using REVIT will be presented followed by case-studies where REVIT was successfully used on Schnabel projects. Projects will include: Real-time data analysis of rock bolts locations relative to existing features, real-time data analysis of a large dam grouting project, and direct implementation of a structural truss cofferdam REVIT model into structural analysis software. We look forward to sharing what we’ve done and are sure that you will have many exciting ideas for implementation within your own projects!

Adam Saylor, Travis Shoemaker

Computational and Automated Design—A Paradigm Shift

​In recent years, personal computers capable of performing computationally intense analyses and simulation have revolutionized the engineering design process. However, the creation of deliverables with traditional CAD drafting has largely remained the same. A typical workflow is to perform structural analyses with one software, geotechnical analyses in another, and manual 2D CAD detailing with a third software, where the design geometry is manually recreated in each software throughout the design lifecycle. Recreation of geometry is a tedious process subject to human error. Enter computational design, replacing the repetitive recreation of design geometry with a seamless connection between analysis software and contract document production. When design parameters are revised, 2D/3D models and other design documents can be automatically and accurately updated. Here, we discuss how Dynamo, Python, Revit, Civil 3D, and analysis software are used to connect our 2D/3D models and contract documents to design analyses. Short case studies will include a record model of the Yeager Airport retaining wall, a grouting model of Round Valley Reservoir, display of instrumentation data for an I95 bridge abutment foundations, real time construction modeling of Boundary Dam rock anchor installation, and design layout of Purdy Dam buttress. Through these examples, we describe how computational and 3D design improves efficiency and reduces the potential for error – and consequentially reduces company risk and liability.

Mike Senior

Restoring RW5 at Yeager Airport: Design and Construction of an 83 ft Tall Hybrid Retaining Wall on the Side of a Mountain

This presentation will focus on Expanded Polystyrene (EPS), or “”geofoam””, as a construction material and its potential applicability in future projects. The presentation will highlight the EPS geofoam design at Yeager Airport as the primary case study.

In 2017 Schnabel Engineering designed an 84 foot tall anchored retaining wall at Yeager Airport in Charleston, West Virginia. To improve long term wall performance by minimizing vertical load on the slope and lateral pressure on the wall, Schnabel proposed partially backfilling the wall with light weight fill. Expanded Polystyrene (EPS) was selected as the backfill material in order to create a more economical and feasible wall design. Schnabel’s lightweight fill solution consisted of a 23,000 cubic yard EPS fill with a maximum height of nearly 50 feet.

The presentation will feature lessons learned during both design and construction of a large EPS geofoam fill. The presentation will also include discussion on the field and laboratory QA/QC methods used to minimize project risk.

Kevin Ruswick

Managing Complex Hydrologic Models using HEC-GeoHMS: Chambers Creek, Texas

​The Chambers Creek watershed in Ellis County, Texas contains 18 NRCS watershed dams that were constructed circa 1957-1960. The overall project is an alternatives analysis for four of the dams where the principal spillways are undersized and do not meet current regulatory criteria. The project is being led by the Alpharetta Office and is a significant project as Schnabel pursues a strategic geographic expansion into Texas. The project is also being supported by the Albany, Chadds Ford, Greensboro offices and represents a collaborative effort across the entire Dams Business Unit on this strategic market initiative. This presentation focuses on the flood analysis portion of the project where the 18 dams and downstream road crossings are being evaluated to quantify existing flooding conditions for various recurrence interval storm events. This will establish the baseline for comparison of proposed improvements to four of the 18 dams to ensure that the spillway upgrades don’t negatively impact downstream flooding. The overall watershed is approximately 60 sq. mi and was sub-divided into 45 sub-basins to represent all of the dams and downstream road crossings. To manage the extensive number of sub-basins and hydrologic parameters in the model, HEC-GeoHMS software is utilized which can easily delineate sub-watersheds and has built-in capabilities to calculate hydrologic parameters such as time of concentration. HEC-GeoHMS has the capabilities to export the sub-basin parameters directly into HEC-HMS which significantly increases the efficiency in creating the large and complex hydrologic model. The computed HEC-HMS hydrographs will be input to a full 2-dimentional HEC-RAS hydraulic model to route the inflow hydrographs through the downstream drainage network to quantify existing and proposed flood elevations and peak flows at locations of important infrastructure. This presentation focuses on the use of innovative solutions to enhance our services as well as challenges we are facing from the strategic geographic expansion into Texas.

Bill Billiet

MXI Slope Stabilization

Auger cast piles up to 100 feet deep with full length cages were used to stabilize a tall slope supporting walls and roadways founded in Potomac clay (residual drained friction angles as low as 8 degrees). Auger cast piles had never been used in an application like this with such deep piles, with full length cages, and installed in hard to very hard clay. The presentation will cover lessons learned and tips for future projects.​


Our Core Values In Action—Friday Sessions

Adam Paisley, Jesse Wullenwaber, and Zach Zukowski

Lessons Learned on Recent Schnabel Dam Grouting Projects

Grouting designs for the Cobbs Creek Reservoir and Round Valley Reservoir projects were implemented in the last two years. The construction documents for these two projects were prepared based on Schnabel’s understanding of grouting industry standards and experience with rock grouting in the last 10 years. As every project presents unique challenges, there were lessons learned that will be considered when developing future grouting programs. Experiences from these and other recent relevant grouting projects will be presented to provide the audience with a perspective of our recent rock grouting design approach, to outline industry changes that affect grouting projects, and to suggest potential adjustments to exploration and construction practices. Additionally, a comprehensive update will be provided on overall Schnabel rock grouting experience.

Bill Billiet

Earthwork for Engineers

Lessons in earthworking, from science to practice aimed at providing the understanding of earthwork to be a valulable consultant. Understand moisture-density relationships, compactive energy effects, effects of subgrade and moisture/water on compaction, best practices for earthworking, dewatering, and improving subgrades, and brief history on the development of earthworking specifications and compaction testing.

Stephen Welsh

Seven Tower Bridge: 9-Year Pile Re-Strike

​Load testing of deep foundation elements is a vital continuation of the geotechnical engineering design services. When designing axially loaded deep foundations, resistance factors for skin friction and end-bearing are incorporated to account for uncertainty in the pile’s ultimate capacity. Load testing, including Pile Driving Analyzer (PDA) or static/dynamic testing, allows the engineer to verify the deep foundation is performing as designed and, in some cases, the design can be refined based on the testing results. For deep foundations that incorporate skin friction, the skin resistance increases over time following driving. This “”set-up”” occurs as pore pressures in the soil dissipate after driving. PDA testing is often performed during initial pile driving; and a pile re-strike is performed within one week to verify the increase in skin resistance.

Schnabel provided geotechnical design and construction services for the Seven Tower Bridge project, a pile-supported office complex in Conshohocken, Pennsylvania, from 2008 to 2011. The project site is underlain by two geologic formations: the Octorano and Conestoga formations, which consist of a metamorphic phyllite-schist and limestone with shale, respectively. During construction, Schnabel oversaw the installation of approximately 509, 13-⅝-inch diameter, open-ended steel pipe-piles using a diesel hammer. PDA testing during initial driving was performed on piles in each geologic formation and within the transition zone to establish a termination driving criteria; PDA testing was not performed on re-struck piles. Following installation of the piles and partial completion of pile caps, construction was halted in 2011. The project development resumed in 2019 and Schnabel was retained to provide construction services, including an evaluation of the existing pile condition and capacity. Pile re-strikes were performed on 60 piles at the site covering the three geologic areas, including PDA testing at 5 piles. This presentation will discuss the initial pile design, PDA testing during construction, and increase in skin resistance (set-up) that was observed, based on the PDA results on the re-struck piles.

Sharon Krock, Joe Bellini (Aterra), Maridee Romero-Graves

A Wild Ride in the NRCS World as a Small Business Joint Venture

Together, Aterra Solutions and Schnabel Engineering have been awarded $10M worth of work (with another $2.5M pending) that would have been unattainable for Aterra alone and unavailable for Schnabel alone. At the time, Aterra had ten employees (3 full-time and 7 part-time) and Schnabel, as a large business, could only pursue small business contracts as a sub consultant to a small business. Aterra and Schnabel entered in to a Small Business Administration Mentor Protégé Agreement in late 2016, joining the two firms in a Joint Venture that is eligible to pursue small business contracts where Aterra needs to perform at a minimum, 40% of the JV’s work. After focused strategic planning between the companies several years prior to the release of the NRCS RFP’s, the Aterra-Schnabel JV won two regional (North and South) NRCS IDIQ five-year contracts in May 2018. Within a few months of the award, we received 19 RFPs, pursued 13, and won eight task orders worth $5.4M even though each contract was capped at $2M per year. Now, we’re two years in to these five year contracts, have won 18 task orders and continue learning valuable lessons, gaining federal experience, utilizing staff from numerous Schnabel offices, and the task orders keep coming, all while sharing the wild ride with Aterra.

This presentation will highlight the lessons we are still learning while working on long-term federal contracts with multiple task orders through our mentor-protégé relationship with Aterra. Coordinating with an outside firm has given us a new perspective on internal procedures and encouraged us to find better ways to use technology to communicate, share files and review concurrently. Because these regional contracts cover the entire eastern US, we identify the best employees for each task order no matter their office location, but for that reason clear roles need to be established early in the project. Working together has renewed and solidified internal relationships and has increased awareness of other office’s capabilities, which are vital to the success of the firm.

Justin Agar, Chris Mayer, Cody Sheaffer

How Tazewell Hybrid Energy Center Connected Offices and Business Units Across Schnabel

Schnabel Engineering (SE) united dams, geological, geotechnical, geophysical and geo business service lines to meet the needs of our clients at the proposed Tazewell Hybrid Energy Center (THEC) in Tazewell County, Virginia. Our Greensboro office won the project, with teaming partner HDR, after years of successful client management and client relationships across several Schnabel offices. To date, our contract value has been $9.2 million dollars, with two main phases of field work – Phase 1, a preliminary study in early 2018 and Phase 2, a more in-depth study in 2019/2020. We are working as a subconsultant for HDR, and the owner Dominion Energy.

The THEC project site is approximately 3,105 acres in heavily wooded, steep terrain. Geologically, the site is very complex, with multiple landslides, faults, and several geologic units with different weathering patterns. The proposed project consists of an upper and lower reservoir, powerhouse, tunnel, interconnect yard, and associated infrastructure. During peak energy demand periods, water from the upper reservoir will be released to the lower reservoir through turbines to generate power. During periods of low power demand, and/or high energy yield, water will be pumped back from the lower reservoir to the upper reservoir. The power grid benefits of such operations include the integration of intermittent power generation source, enhancement of grid stability, and supply of other ancillary services, all of which are very important to Dominion as they try to balance renewable and traditional energy sources.

To meet our client’s complex needs and aggressive schedule of being up and running by 2030, our Greensboro staff united personnel from the Chadds Ford, Blacksburg, Newport News, and Richmond offices to lead the field and lab efforts. Geophysical services were lead out of the Chadds Ford and Richmond offices. The Phase 1 geophysical investigation included approximately 2 miles of seismic refraction, approximately 1 mile of electrical resistivity imaging, and three locations of multi analysis of surface waves (MASW) over the course of 2 months. The Phase 2 geophysical investigation included approximately 8.5 miles of seismic refraction and approximately 1 mile (MASW) over the course of 4 months with a full-time crew of 4-5 people. These methods provide information about overburden thickness, weathering patterns, faults, landslides, and depth to and rippability of rock.

The geotechnical investigation efforts were led out of the Greensboro office with field, geotechnical engineering, and laboratory support provided by Blacksburg. The geotechnical investigation included a work plan, boring observation, in-situ testing, and downhole televiewer surveys. Phase 1 included 8 borings and 2,028 lf of drilling, and Phase 2 has a proposed 41 borings ranging from depths of 100 to 1,100 feet for a total of 11,151 linear feet of drilling. The laboratory program includes index properties of the soils and mechanics testing such as one-dimensional consolidation and triaxial testing of undisturbed or remolded samples. Index testing consisted of moisture content, grain-size distribution, and Atterberg limits testing to determine the engineering properties of the in-situ material at the project site.

SE personnel worked together to provide the client with the information they need to assess the risks of the site, and to create a feasibility-level design for the complex structures. Ultimately, the objective of this project is to enrich economic opportunity to the region while also constructing infrastructure that will be a key facilitator for future renewable energy demand. The THEC project promoted collaboration and communication between offices so that HDR and Dominion experienced the full effect of “”Built Better. Together.

Nicole Mathis, Tom Fitzgerald, Matt Koziol

Terror Lake in Kodiak, Alaska — An Interoffice Success Story

​The Upper Hidden Basin Diversion Project located on Kodiak Island in Alaska was designed and constructed between 2014 and 2019. The purpose of the project is to divert stream flow from a four square mile drainage area into the existing Terror Lake Hydroelectric Project operated by Kodiak Electric Association (KEA). The main project features include a 1.22-mile long tunnel, two earthen embankment diversion dams, a 0.6-mile-long water conveyance pipeline between the dams, and a 4-mile-long access road. The rural location of the project, multiple design disciplines, and accelerated schedule added significant challenges to this project. The project was designed and the construction managed by numerous folks from both the dams and underground business units representing six different office locations in four time-zones. This presentation provides details on the challenges faced and overcome by our committed team of engineers, geologists and construction managers.


Our Core Values In Action—Saturday Sessions

Jacob Hollander, Rich Calderon

HoleBASE: A New Geotechnical Database & Subsurface Visualization Program

HoleBASE is a suite of software that includes a geotechnical database, CAD, and Excel extensions. Unlike gINT which is customizable by any individual, leading to a multitude of templates and data conventions, HoleBASE is comprised of a tiered structure of Administrators, Project Managers, and data editors. This system allows for projects from multiple offices to be contained in a common database working under a universal framework leading to a more consistent, product.

This presentation will highlight several key capabilities of HoleBASE for geotechnical engineering purposes. Such features include producing fully customizable borehole logs, stick figures, 3D modeling in CAD, template editing, customizable excel tables, and site planning. These functions can streamline field investigations, improve QA/QC, speed report writing, and aid in design purposes.

Allen Cadden, Carl Pucci (Ovela)

Asset Management from the 2 Million Foot Level

​Monitoring the nations infrastructure is a daunting task. Every major structure has O&M plan focused on looking at specific areas of concern or identified risks. But who is looking at the system as a whole? How many times has a failure initiated in an area we didn’t suspect? Using the ESA Sentinal 1 satellites (and other coming on line rapidly) data can be collected easily and on a regular 6 day cycle across an entire system, anywhere in the world. Whether this is a pipeline, railway, highway, bridge, dam and reservoir, mine, urban center, landslide prone area, or just an open field the InSAR tools can be a great asset to identify movements in unexpected areas allowing engineers and managers to respond. This presentation will demonstrate the capablities of satellite based InSAR and ways Schnabel can be an integral part of a clients asset management or emergency response programs.

Egboche Unobe, J. Hawkins Gagnon

Site-Specific Challenges to Sensemetrics Cloud-Based Platform for Real-Time Monitoring: Lessons from Tazewell Hybrid Energy Center & Lake Vermilion Dam

The popularity of cloud-based monitoring systems is skyrocketing as geotechnical engineering experts begin to appreciate a cloud-based platform that allows for relatively easy data management, real-time condition monitoring, and integration of new and existing on-site sensors, including: inclinometers, piezometers, and weather stations. The sensemetrics platform represents an improvement in three technical focus areas: sensor systems, information management, and data visualization. The sensemetrics platform allows for shared sensor data access and provides plug and play support for existing and new geotechnical sensors, potentially reducing costs.

The goal of this presentation is to show that the practicability of the sensemetrics system will depend on site-specific characteristics including the extent of cellular network coverage, and the availability of a reliable power supply source.

This paper outlines recent challenges faced at Lake Vermilion Dam in Danville, IL and the Tazewell Hybrid Energy Center in southwestern, VA. At Lake Vermilion, challenges were related to freezing temperatures and inadequate sunlight. At the proposed Tazewell Hybrid Energy Center, the sensemetrics monitoring platform will be based on a GeoNet wireless network that relies on cellular service to allow for data collection from multiple, and widely distributed, Vibrating Wire Piezometers (VWPs). The GeoNet network will be integrated into the sensemetrics cloud management platform to ease collation and aggregation of the data collected.

Steve Brandon, Wen Lee

A Case History of Rock Slope Stabilization on the C&O Canal Near Paw Paw, West Virginia

​The Chesapeake and Ohio (C&O) Canal runs alongside the Potomac River from Cumberland, Maryland to Georgetown in Washington, DC, Construction of the C&O Canal started in 1828 and was finally completed in 1850. One of the most ambitious features of the project was construction of a 3,118-ft long tunnel near Paw Paw, West Virginia. Construction of the tunnel was deemed necessary to avoid 5 miles of loops along the Potomac River that had steep cliffs along which canal construction was nearly impossible. The north end of the tunnel includes an approximate 890-ft long open cut rock slope approach to the tunnel portal. The east slope of the approach cut has been subject to planar failure rock slope instability since its construction. This presentation describes the construction limitations, design and construction of rock slope remedial measures for this historic structure. The presentation will also highlight the collaboration between Schnabel offices and use of one of the company’s drones to provide topographic and aerial imagery which were integral to layout of the stabilization system. Stabilization of the slope included scaling, rock dowels/bolts, pre-cast concrete shear keys, weep holes and rockfall protective mesh.

David Railsback, Mike Taylor

Conklingville Dam: A Multi-Dimensional Investigation

Conklingville Dam impounds the Great Sacandaga Lake, New York’s largest man-made reservoir. The dam was constructed circa 1930 and is operated by the Hudson River – Black River Regulating District. As the dam approaches 100 years of service, the Regulating District is implementing a rehabilitation program. A primary goal is to repair the 425-foot long concrete ogee spillway weir and the narrow 70-foot tall bedrock foundation on which it is constructed. Directly adjacent to the spillway structure is a 50-foot deep spillway channel cut from bedrock that also leads to a hydropower facility owned and operated by Brookfield Renewable. The concrete spillway weir has gradually deteriorated, the bedrock foundation has eroded, and there is active seepage through both concrete and rock. The evaluation of the structure included a comprehensive investigation to characterize the conditions of the spillway structure and foundation to assist the team in recommending repairs. The field investigations included physical surveys, digital scanning, drone photogrammetry and thermal imagery, 3D sonar bathymetry, underwater ROV video, concrete and rock coring, geologic mapping, geotechnical drilling, packer testing, and downhole and surficial geophysics. The program combined the results of these site characterization techniques into a 3D geologic model to facilitate evaluation, design, and stakeholder communication. Project challenges included difficult site access, coordination among multiple stakeholders, and limited work windows inside the active and fluctuating intake channel. The dam provides flood control and recreational releases, as well as power generation, requiring complex project scheduling and real-time operational adjustments by the Regulating District in response to project obligations and seasonal weather patterns. This presentation will review the investigation program and resulting 3D model, and discuss the value gained and lessons learned from the various exploration techniques.

Allen Bowers, George Aristorenas

Merging Old and New: Case Study on Designing Micropile Support for Existing PIF Foundations

​The 901 North Fairfax St project in Alexandria, VA was a complex design project which involved the repurposing of an existing 40 year old hotel into condos and townhomes. This change in use of an existing structure involves changes in loading, and any revisions to the structure to accommodate the loads needed to be current code compliant. The project involved many challenges including analysis of no-longer-used and poorly-understood foundation elements, complex interaction between the old elements and new micropiles, intricate loading and load staging, strict deflection tolerances, and difficulties in overcoming the semantic communication barrier between geotechnical and structural engineers. The existing hotel is supported primarily by Pressure Injected Footings (PIFs), or Franki Piles. PIFs were a popular foundation option 50 years ago and are similar to rammed aggregate piers of today. The developer desired to reuse the existing PIF foundations, which varied in quantity from a single PIF supporting a single column, to 8 PIFs supporting several shear walls. It was determined that the PIFs alone did not have enough capacity to support the new loads resulting from repurposing. The design utilized three-dimensional (3D) finite element modeling to analyze the integration of new and existing foundation elements. This presentation will show the 3D finite element modeling approach we took including calibrating the PIF model to a load test to understand how it behaves, incorporation of the micropiles with the existing PIFs, how loads were applied and varied over time, and our final design recommendations. We will also present some general lessons learned including overcoming communication barriers between geotechnical and structural engineers.

Bios


Aaron Collins

Aaron is based out of the Greensboro office and has been with Schnabel for over 12 years. During his time with Schnabel, he has contributed to the design and construction of several high hazard dams. Aaron is currently the onsite senior resident project representative for a 40 million dollar construction dam rehabilitation project in Black Mountain, NC. Aaron received his Bachelor’s Degree in Civil Engineering from Old Dominion University.


Aaron Montgomery

Aaron Montgomery is co-founder of CarLotz, a high growth start-up that is disrupting the used automotive retail market through its innovative vehicle consignment and non-commission sales model. Prior to CarLotz he was a consultant at McKinsey & Co. and a sales executive at Kiva Systems, a robotics company that was acquired by Amazon in 2012. Aaron began his career at McMaster-Carr, an industrial product distributor, where he fast-tracked through department manager roles in sales, operations, and finance to become the youngest regional manager in the company.

In addition to his work at CarLotz, Aaron is also a speaker, adviser, and instructor. He currently teaches Entrepreneurship and Strategy at Virginia Commonwealth University. Aaron is a two-time Inc. 5000 honoree (2018, 2019), a two-time finalist in EY’s Entrepreneur of the Year Program (2015, 2019), and was named Executive Partner of the Year by the Society of Human Resource Managers (SHRM) in 2013.

Aaron holds an A.B. in Economics from Harvard University and an MBA from Harvard Business School. He has served on the boards of the United Way of Greater Richmond and Petersburg and Junior Achievement of Central Virginia.

Adam Paisley, PE

Aaron is based out of the Greensboro office and has been with Schnabel for over 12 years. During his time with Schnabel, he has contributed to the design and construction of several high hazard dams. Aaron is currently the onsite senior resident project representative for a 40 million dollar construction dam rehabilitation project in Black Mountain, NC. Aaron received his Bachelor’s Degree in Civil Engineering from Old Dominion University.


Adam Saylor

Adam joined Schnabel in October 2018 as an IT specialist in the Chadds Ford office. In addition to day to day IT operations, he has a long background in Programming and Computer Science and has been involved in companywide efforts to introduce BIM, computational design, and other emerging technologies. Prior to joining Schnabel, he worked at Bentley Systems developing and testing new features for the MicroStation product line.


Allen Bowers, PhD, PE

Allen specializes in soil-structure interaction analyses, geostructural design, data reduction, and risk-based approaches. His PhD research was on implementing geothermal piles in bridge foundations to harvest geothermal energy for bridge deck deicing and temperature control. He has presented his work and research at over 10 national and international conferences and workshops and has authored or coauthored over a dozen papers. With a strong background in agriculture, he appreciates the soil for not only its material strength properties and source of geothermal energy, but its foundational role in food production as well.

Allen Cadden, PE, DGE

Allen is a Principal in Chadds Ford, PA where he supports Schnabel’s GeoStructural Practice. Allen received his BSCE and Masters of Engineering from Virginia Tech, Blacksburg, Virginia a long time ago and is a licensed engineer in 11 states.


Andrew Kolbert, PE

Andrew is a Senior Engineer in Schnabel’s Knoxville, TN office with 5 years of hydraulic and geotechnical experience. He received his undergraduate degree from the University of Tennessee and is a licensed engineer in the state of Tennessee. He has experience with the design and inspection of high hazard coal refuse and freshwater dams.


Andrew Vasko, PE

Andrew is a Project Engineer in Schnabel’s Chadds Ford, PA Office and has been with the firm for five years. His responsibilities include the design and analysis of dams and spillways. Over the past few years, Andrew has worked across various Schnabel offices on structural design projects.


Arif Bhuiyan, PhD, PE

Arif is a Project Engineer in Charlottesville office. Arif’s primary focus has been in Geotechnical Earthquake Engineering for the past 10 years. He has also worked as a Geotechnical professional on transportation, residential and commercial projects.


Bill Billiet​, PE

Bill is an Associate in Schnabel’s Rockville, MD office. He has been with the company over 13 years providing geotechnical engineering services for a wide variety of projects, in particular transportation related infrastructure and vertical (building) construction, both locally and internationally. He has had a significant role on several major design-build projects, including the Inter-County Connector and the Dulles Metro Silverline in the Washington, DC area.


Brent Scott, PG

Brent has worked in large and small environmental consulting firms from California to Virginia during his 32-year career before coming to Schnabel’s Columbia, SC office two years ago. He is a PG in multiple states.


Carl Pucci

Carl went from Norfolk’s ODU (Go Monarchs!) to Estonia, in Northern Europe, to work on e-Government systems and radar spacecraft observing the Earth with mm accuracy through PS-InSAR. Since then he’s worked with American and Estonian Presidents, UN Geneva, the European Union and the European Space Agency. Carl is a Principal of Ovela59.com, and more importantly, an ‘epic Dad’ according to the kiddos he has dragged around the planet (and back) a few too many times – and counting.


Chadd Yeatts, PE

Chadd is an Associate in the Geotechnical Business Unit based in Blacksburg, VA currently leading Schnabel’s firm-wide Power and Energy market pursuit. He has over 20 years of geotechnical engineering and project management experience in transportation, power, and commercial projects. In his current role at Schnabel, Chadd has transitioned from project management and execution to the pursuit phase leading business development efforts for Power, Transportation, and all things Schnabel. Chadd has a BS and MS from Virginia Tech. Chadd is heavily involved in his community serving on the Board of Directors for several charities/foundations and is an avid golfer and fly-fisherman.


Chris Mayer

Chris is a Staff Geologist in the Chadds Ford, PA office who has been with Schnabel for the last 2 years. Chris’s experience is in the application of geotechnical, geophysical, and geological investigations and in karst evaluations. Chris’s free time is spent on fixing vintage motorcycles and hiking outdoors.


Cody Sheaffer

Cody is a Senior Staff Geologist in the Richmond Office. Cody graduated with a B.S. in Geology. He has worked in the industry for 6 years and his main focus is on geophysics related projects.


Corey Schaal, PE, GIT

Corey has been with Schnabel for about four years. He is a graduate of Ole Miss with a BS in Geological Engineering and a Virginia Tech graduate with a MS in Civil Engineering. His responsibilities include geotechnical analysis and design for dams projects.


Daniel Schultz, EIT

Daniel has three years of experience in the analysis and design of hydraulic structures including dams, spillways, embankment failure and flooding, and surface hydrology. He graduated with his Bachelor’s from Penn State University in 2016. Throughout his time at Schnabel he has been involved in 3D modeling and Computational Fluid Dynamics (CFD) projects, as well as presenting on related topics in the CFD Users group.


David Carpenter, PGP

David is a Senior Geophysicist in the Richmond, VA office. He joined the Schnabel team 7 months ago and has over 11 years of experience in the application of near-surface geophysical methods to engineering and environmental projects including geo-design, dams, transportation, energy, and tunnels.


David Ebinger, PG

David is in Schnabel’s Columbia, SC office. David worked for the SC Department of Health and Environmental Control for a number of years before coming to Schnabel 7 years ago. He is a SC PG and will soon be a NC PG.


David Railsback, PE

David is a Senior Engineer in the Albany, New York office, with a background in water resource and dam safety engineering. He has over 10 years of experience including dam rehabilitation, pump and pipeline systems, and environmental mixing. He is responsible for project management, client communications, coordination of field activities and analysis, and project delivery. He received his undergraduate and master’s degrees in civil engineering from Cornell University, and is a Professional Engineer in New York.


​Del Shannon, PE

Del has 30 years of experience working in the civil, geotechnical, and environmental engineering fields, including extensive experience in concrete and embankment dam safety and dam design. Del regularly contributes his expertise to local, national and international committees, including ICOLD, USSD, and ASDSO. He is regularly invited to give dam related presentations internationally, including China in 2008 and in 2010 at the British Dam Society annual conference. In 2007 he received the Award of Excellence in the Constructed Project from the USSD for Pine Brook Dam, and his projects have received two National Dam Rehabilitation Project of the Year Awards from the ASDSO (2016 – Beaver Park Dam and 2018 – the Hope Mills Dam).


Don Deere, PE

Don is a Principal in Schnabel’s Longmont, CO office and was a co-founder of Deere and Ault Consultants in 2005. Don’s expertise is in engineering geology and rock mechanics of dams, tunnels and rock cuts. He has a Bachelor of Science degree in Geology from the University of Wisconsin, and a Master of Science degree in Geotechnical Engineering from the University of California at Berkeley. He is engineer of record on a dozen dam design and rehabilitation projects in Colorado. He has consulted on multiple tunnel projects throughout the world including South America and Asia and has considerable expertise in pressure tunnels for hydro-electric schemes. He has multiple publications on dams and tunnels, has guest lectured at the Colorado School of Mines and University of Texas and was the 2011 Schnabel lecturer.


Egboche Unobe, GIT

Egboche is a Senior Staff Scientist at Schnabel’s Greensboro, NC office. He joined 2 years ago and specializes in Engineering Geology tasks related to site investigations, instrumentation and material testing. His responsibilities at Schnabel have so far involved drilling and construction oversight, installing dam monitoring instruments, and performing filter, settlement and slope stability analyses.


Emily Gibson, PE

Emily is a geotechnical engineer in Schnabel’s Chadds Ford office and has been with Schnabel for four years. In addition to working with the dams group, she also has 10 years of experience performing seismic hazard analyses and risk/reliability assessments.


Eric Snavely, EI

Eric is a Senior Staff Engineer based in the Greensboro office where he performs inspections, analysis and designs of dams and hydraulic structures. He sits on the WIN Steering committee and is an active member of Schnabel’s Internal CFD Users Group.


Gary Horninger, PE

Gary has over 30 years of experience with dam construction and Resident Engineer/RPR services. He has been with Schnabel for over 20 years starting with the CPS group in West Chester before joining the Dams Group. Gary has both undergraduate and graduate degrees from Drexel University and is a licensed professional engineer in several states.


George Aristorenas, PhD, PE

George is a technical principal with Schnabel’s Geostructural Group. Having a MS degree in Structural Engineering (University of the Philippines) and PHD degree in Geotechnical Engineering (Massachusetts Institute of Technology), George has over 30 years of experience in projects involving soil-structure interaction.


Glen Frank

Glen is a Senior Associate with Schnabel Engineering. He has over 20 years of experience serving technical and managerial roles on major tunnel projects working for CM, design, and construction firms.


J. Hawkins Gagnon, PG

Hawkins is a Project Geologist in the Greensboro, NC office. Hawkins leads Greensboro’s Geoscience Group and has been with Schnabel for the last 8 years. Hawkins specializes in site characterization but also has gained valuable experience in wide variety of engineering geology related tasks that have included instrumentation, 3D-modeling, grouting, and others.


J.R. Collins, PE

J.R. is a Project Engineer working out of the Alpharetta, Georgia office. J.R. has a B.S. in Civil Engineering from the University of New Hampshire and has been with Schnabel since 2008. Since joining Schnabel, J.R. has been involved in a variety of dam-related projects serving as a designer, field representative and/or project manager.


Jacob Hollander, GIT

Jacob is a Senior Staff Scientist with the Dams business unit in Greensboro. As part of the Dams business unit, Jacob conducts subsurface investigations, scientific analysis of engineering and geologic problems, and has helped develop the use of HoleBASE within the Greensboro office for the last 3 years. He loves owls and collecting far too many rocks.


James Parkes, PE

James has over 20 years of geotechnical engineering experience and has been with Schnabel for the last 3 years. He has BS and MS degrees from Virginia Tech and is licensed in 10 states. His experience includes analyses of tunnels, shafts, dams, levees, and foundations, including forensic analyses of structure and embankment failures such as the one that will be discussed here.


Jesse Wullenwaber

Jesse graduated with a Bachelor’s in Civil Engineering from the Virginia Military Institute in 2004 and has spent most of his career since then with Schnabel’s Dam Engineering group. Jesse has been involved with four remedial dam grouting projects, including USACE’s East Branch Dam slurry control grouting program.


Johanna Mikitka Simon, PE

Johanna is a Senior Engineer in the Chadds Ford, PA office. Johanna has been part of the geostructural group for over 13 years and is currently instrumenting lots of infrastructure. She enjoys a good challenge… hybrid wall designs, managing the Yeager Airport RW5 RSA project, raising 3 kids. In addition to engineering, Johanna directs a children’s choir and runs a handcrafted accessories shop.


Joseph Bellini, PE, PH, D.WRE, CFM

Joseph is Vice President and Principal Water Resources Engineer at Aterra Solutions, a small-business firm located in the Philadelphia area, with 31 years experience specializing in severe flood analyses; dam and levee engineering; and probabilistic flood hazard studies. He has a BS in Civil Engineering from Penn State University, MS in Civil/Water Resources Engineering at the University of Pittsburgh, and is an adjunct professor at Villanova University.


Justin Agar, PE

Justin is a Staff Professional in the Chadds Ford, PA office who has been with Schnabel for the last 1.5 years. Justin has worked on a variety of geotechnical investigations over the years, mostly on geostructural, from New Orleans, Louisiana to Charleston, West Virginia. In his free time, Justin enjoys a wide variety to competitive sports to restoring old cars and trucks.


Kevin Ruswick, PE, CFM

Kevin is a Senior Associate in Schnabel Engineering’s Clifton Park, NY office, specializing in Water Resources Engineering. He has over 25 years of experience in a wide variety of water resources engineering projects including dam breach analyses, spillway rehabilitation projects, flood control systems, stormwater management, and stream restoration. He also has significant experience in transportation related hydrology and hydraulics and is working with the Transportation Group in expanding Schnabel’s presence in this sector. He received his undergraduate degree in Civil Engineering from Northwestern University and his Master’s Degree in Water Resources Engineering from the University of California at Berkeley. He is a licensed professional engineer in New York, Illinois, Delaware and Colorado and is also a Certified Floodplain Manager.


Kortney Brown, PE

Kortney is a professional engineer with over 11 years of multidiscipline dam engineering experience as a project manager, engineer of record, business developer, and lead designer. Kortney is an expert level draftsperson, with extensive experience designing, rendering, and analyzing solutions for most aspects of dam engineering.


Laura Shearin-Feimster

Laura is a Senior Engineer in the Greensboro office where she specializes in Hydrology and Hydraulics. She received her undergraduate degree from NC State, and her Master’s from Duke. She currently spends a lot of her time yelling about Lake Lure across the hall with Sina Khodaie.


Libby Dishner

Libby is an adjunct professor with Community College Workforce Alliance (CCWA). She is also a founding partner of Cresco Coaching and Consulting. As a professional coach and consultant, Libby leverages her 25+ years in the corporate world, most recently as an HR executive. She holds a master’s degree in Human Resources and a credential from the International Coach Federation (ICF). With Libby’s experience, education, and zeal for continuous learning, it’s no surprise that she enjoys her work with individuals, teams, and organizations as they develop and implement leadership programs, coaching, and organizational strategies.


Maridee Romero-Graves, PE

Maridee is a Senior Engineer with the Greensboro, North Carolina office. She has over 12 years of experience in dam engineering and over eight years of experience as a project manager and assistant project manager for a variety of projects, including recreational, flood control, and multiple NRCS dams. Maridee is part of the Company’s water resource group. She focuses on hydrologic and hydraulic (H&H) analyses, dam inspections, dam assessments and design for new and existing dams. Maridee, who is bilingual, received a B.S. in Chemical Engineering from the Central University of Venezuela, and a Master of Civil Engineering from North Carolina A&T State University. She is a licensed Professional Engineer in North Carolina and Virginia.


Mark McLean, PE

Mark is a Principal in Schnabel’s Longmont, CO office and was a co-founder of Deere and Ault Consultants. He has a Bachelor of Science degree in Civil Engineering from Colorado State University. Mark’s experience is primarily in water resources engineering related to Colorado’s system of water laws, focusing on water rights engineering planning and implementing projects for municipal and agricultural water supply. Mark’s practice has also included hydraulics and hydrology, dam rehabilitation, hydraulic structures, and pipelines. He and his wife enjoy traveling, especially camping in their Volkswagen camper van.


Matt Koziol, PE

Matt has over ten years of professional experience in the tunneling and underground construction industry and has been a risk manager and moderator on various projects for the past seven years across all of Schnabel’s business lines. He received his Bachelor of Science in Civil Engineering from Washington State University in 2008 and his Master of Science in Civil Engineering from the University of Washington in 2013 specializing in Geotechnical Engineering.


Michael Taylor, PE

Mike has over 34 years of project development, design and construction experience on geotechnical, water resource, infrastructure and heavy civil-works projects; including dams/levees, transportation, industrial/power, earthworks, mining/underground, and marine/waterfront facilities. Mike has a BS in Geology/Water Resources from the State University of NY at Oneonta, and a BS in Civil Engineering from Clarkson University. Much of his free time is dedicated to volunteer work for those in need, and the great outdoors.


Michelle Bolding​, PE

Michelle is a double Virginia Tech graduate (BS & MS), with 14 years of experience in consulting. She started her career in the New York/New Jersey metropolitan area, joined Schnabel’s Charlottesville office in 2010, and relocated to the Richmond office in 2014. When not working on I-95, she plays an excessive amount of volleyball. She is a registered PE in Virginia, North Carolina, and Washington.


Mike Senior

Mike is a Senior Staff Engineer in Schnabel’s Chadds Ford office and has been with the company for 3.5 years. Mike works in the Geostructural design group, specializing in support of excavation, deep foundations, retaining walls, slope stability, and structural design. In his free time, Mike likes to hike and participate in International Habitat for Humanity.


Mitch Youmans

Mitch has been with Schnabel since 2018, starting in the Sterling, VA office and transferred to the Chadds Ford, PA office. He is part of the Geodesign Team and is involved with subsurface investigations and geotechnical and geostructural design projects. Mitch received both his undergrad degree in Construction Engineering and Management and Master’s Degree in Civil Engineering at Virginia Tech.


Nathan Young​, EIT

Nathan is a Senior Staff Engineer in the dams group at the Chadds Ford office where he focuses on inspection, analysis, and design of dams and hydraulic structures. He received his BS and MS from Utah State University with his research focused on physical hydraulic modeling of nonlinear weirs (e.g., labyrinth and piano key). He helped spearhead Schnabel’s Internal Computational Fluid Dynamics (CFD) Users Group in 2019, in which he has lead several trainings and presentations.


Nicole Mathis, EI

Nicole joined Schnabel’s Greensboro office in May 2017. She studied at North Carolina State University where she earned a Bachelor’s of Science in Biological Engineering with a concentration in stormwater and wetland restoration. As a Senior Staff Engineer in the Dams business unit, Nicole has assisted in the preparation of hydraulic and hydrologic analysis, erosion and sediment control plans, design drawings, technical specifications and reports.


Ray Eldridge, PE

Ray is a Principal and Branch Leader in Schnabel’s Boise, Idaho office. Ray holds a B.S. and M.S. in civil and environmental engineering from Washington State University. Over his 36-year career in consulting engineering, he has served as project engineer, project manager and principal-in-charge on a wide variety of multidisciplinary water projects across the U.S. His primary technical expertise incudes hydraulic analysis and mechanical and structural design of hydraulic structures, large gates and valves, pumping stations and fish facilities. In support of engineering projects, Ray and the Boise staff design, fabricate, machine and test prototype equipment, physical hydraulic models and unique single purpose tools.


Rich Calderon

Rich joined Schnabel (Greensboro) in August 2018 as a CADD Tech III, bringing over 20 years’ experience in CAD and Civil Design. Rich specializes in grading and earthwork modeling using Civil 3D. Since joining Schnabel, Rich has worked to further develop the HoleBase application for Greensboro Geotechnical department.


​Samuel Kees, PE

Samuel is a Senior Engineer in the Greensboro office and has been with Schnabel for 11 years. His experience includes the inspection, evaluation, and design of earth and concrete dams and dam rehabilitation projects.


​Sara Doran, EIT

Sara is a Senior Staff Engineer in the Baltimore, MD office and has been with Schnabel for the last 2 years. She graduated with her Bachelor’s and Master’s degrees in civil engineering from Texas A&M. Her background is in the design of tunnel design for underground projects in rock and soft ground.


Scarlett Kitts, PE

Scarlett is a civil engineer in the Greensboro office. She has been working on the North Fork Project for 5 years, through design and construction. She enjoys encouraging people to celebrate Pi Day and all other nerdy holidays.


​Seth Frank, PE

Seth is a Senior Engineer in Schnabel’s Knoxville, TN office. A graduate of the University of Tennessee, Seth has almost 11 years of geotechnical engineering experience, including the design and inspection of high hazard coal refuse and freshwater embankment dams.


Sharon Krock, PWS, F.SAME

Sharon is a Professional Wetland Scientist, delineating wetlands, coordinating permitting efforts, and serving as a resource for the entire company regarding any projects with wetland/water impacts. Sharon started her Schnabel career in 2001 and has added business development and orchestrating strategic partnerships to her repertoire. Sharon manages the Mentor-Protégé relationship that Schnabel has with Aterra Solutions and is always on the lookout for the next opportunity.


​Sina Khodaie, PhD

Sina is a structural engineer in the Greensboro office with a sound background and experience in finite element analysis. He received his PhD from the University of South Carolina with his research focus on numerical analysis of concrete structures.


Stephen Miller, PE

Stephen has degrees from Virginia Tech in Mining and Minerals Engineering (MS, BS) and Geophysics (BS). He has a background in providing design and assessments for tunneling and underground facilities. In his spare time he enjoys working with embedded microcontroller systems, sensors, and the Internet of Things.


Stephen Welsh, PE

Stephen (Steve) is a Senior Geotechnical Engineer in the Chadds Ford office. He’s been with Schnabel for 2 years and has enjoyed working on the wide variety of interesting and challenging projects. In his spare time, he enjoys spending time with his wife and 3 year old son, running, and hiking.


Steve Brandon, PE, PG

Steve is a Principal in Schnabel’s Sterling, VA office. Steve graduated from the Missouri University of Science & Technology with B.S. and M.S degrees in Geological Engineering and has 34 years of experience as a consulting engineer focusing on design and inspection of tunnels, underground structures, and rock slopes. He enjoys hiking, dog rescue, and supporting the Washington Capitals and St. Louis Blues hockey clubs.


T.R. Fluker, PE

T.R. is department manager of the construction services group in Schnabel’s Richmond office and has been with the company for 18 years. He received his Bachelor’s Degree in Civil Engineering from Virginia Tech and Master’s degree from N.C. State. T.R. also serves on the Board of Directors for the ACI’s Virginia Chapter. When T.R. is not working for Schnabel, he is typically working on his second career herding cats (his two young kids).


Todd Roberts, PG

Todd is the Director of Infrastructure for sensemetrics and is based in Denver, Colorado. He has over 20 years of geotechnical engineering and instrumentation experience working globally. Some of his recent project experience includes Yeager Airport, Oroville Spillway, and Cobbs Creek Reservoir.


Tom Fitzgerald, PE

Tom has 24 years of experience performing evaluation and design for new dams and dam rehabilitations across the US. Much of Tom’s recent experience has been associated with FERC regulated hydropower dams, mostly located in the Pacific Northwest. He was the engineer of record for the dam, access road and pipeline portions of the Upper Hidden Basin Project at Terror Lake in Kodiak, AK.


Travis Shoemaker, EIT

Travis is a Senior Staff engineer in the dam engineering group in the Chadds Ford office. Over the last year and half, Travis has performed design drafting of dam rehabilitations, dam inspections, and construction observation. Additionally, he has been involved in BIM implementation, remote sensing applications, and computational/automated workflow development.


Walt Rabe, PE

Walt joined Schnabel in 2001 and serves the Board of Directors as the President/CEO of Schnabel Engineering, working closely with the Board of Directors and others in senior management to promote the vision of the firm and develop strategies to achieve that vision. Prior to his current role as President/CEO, he was responsible for management of Schnabel’s Geotechnical Business Unit and was instrumental in building Schnabel’s international practice. Walt has 30 years of experience and is a licensed engineer in seven states and the District of Columbia.


Zach Zukowski, EIT

Zach is a Senior Staff Engineer in the Chadds Ford office specializing in geotechnical and dam engineering. Zach’s experience includes conducting subsurface investigations, construction oversight, dam inspections, laboratory data analyses, and geotechnical analyses. Zach has been a field representative for several projects since starting at Schnabel in 2016 and is currently serving as the resident project representative at the Round Valley Reservoir Structures Refurbishment and Resource Preservation Project, which includes both rock foundation grouting and embankment rehabilitation.