IFCEE 2018: Case Histories and Lessons Learned

The Fargo water treatment plant improvement project is a $104 million plant addition located in Fargo, ND. The original foundation design for the addition consisted of 346 each 42-in. diameter drilled piers; similar to the existing plant foundations. A value engineering (VE) alternate foundation system was proposed that consisted of a 1-for-1 replacement of the drilled piers with auger cast-in place (ACIP) piles of equivalent capacity. The VE alternate proposal saved approximately $4 million and 15 weeks in the construction schedule. The ACIP pile VE alternate was ultimately selected for the project. A pile load testing program was undertaken to verify design assumptions and optimize the design of the piles by determining the frictional resistance being developed along the length of the test pile within each subsurface layer. The load testing program consisted of four reaction piles, and one sacrificial compression load test pile that was tested to a maximum test load of 704 kips. The pile load test was successful in verifying design assumptions, and verifying that the proposed ACIP pile was an appropriate deep foundation element for the project.

Due to the variable subsurface conditions of the bearing strata consisting of older alluvium with cobbles and boulders at this site in Honolulu, Hawaii, there are concerns as to whether foundation drilling contractors would be able to install augered cast-in-place (ACIP) piles deep enough into the supporting strata to obtain the recommended pile capacity. This project included performing a single static load test and 12 high-strain dynamic load tests to evaluate the ACIP pile capacity embedded in older alluvium containing abundant cobbles and boulders. The ACIP piles were 600 mm in diameter and extended to 13.3–23.9 m in depth. To confirm if the soil/rock bearing stratum will provide adequate end bearing resistance, drilling refusal criteria were incorporated into the foundation installation specifications. By terminating ACIP piles on the hard boulders and basalt formation, end bearing capacities ranging between 490 and 1,380 kilonewtons were realized in the installed ACIP piles tested. The total capacities of the ACIP piles ranged from about 2,620–4,180 kilonewtons. On the average, the end bearing component provided only 20% of the total ACIP pile capacity.

Continuous flight auger (CFA) piling technique has gained popularity in inner urban areas of Egypt due to its economical, low-vibration, and quick features compared to other pile drilling techniques. A CFA pile installation rate of 15 piles per day per auger rig can be reached in favorable soil conditions. However, several researchers have described situations where CFA pile installation can lead to surface subsidence. In this paper two case studies are presented and discussed where CFA pile construction in the Nile Valley region of Egypt have led to settlement of adjacent structures. In both cases the pile construction was halted due to effects on adjacent structures. In one of the two cases work was resumed after a revised pile installation methodology was introduced and minimal effect on the adjacent structures was observed afterwards. Moreover, other typical soil conditions which may lead to the settlement problem during CFA construction in Egyptian Nile Valley region have been discussed along with possible solutions to minimize this effect on adjacent structures.

Five piled foundation case histories from construction projects in Greater Vancouver, British Columbia are presented. Driven steel pipe piles and drilled shafts had to be repaired to address damage or concerns regarding insufficient ultimate capacity in compression, uplift and/or lateral loading. For many of the piles, lateral loading requirements under extreme seismic events controlled the design, which in turn required minimum embedment depths. These case histories demonstrate that piles which drive short are more difficult to deal with than piles which drive long. In two of the case histories, the presence of confined water pressures resulted in disturbance of the material at the drilled shaft base elevation. Driven pile obstructions occurred because of large glacial erratics that are often present in till-like deposits. In some cases, obstructions were caused by tree trunks entrained within ancient slide debris. Repair methods had to be used when drilling out and replacing obstructed piles was not possible. The repair methods included: driving stinger H-piles inside damaged pipe piles to increase vertical capacity, installing anchors inside and outside driven pipe piles to increase uplift resistance, base-grouting drilled shafts to harden loose zones at the base, and construction of a composite foundation with a shaft carrying lateral loads and a near-surface footing carrying compression loads. Identifying pile installation risks early in the project and providing guidance and potential remediation techniques for the piling contractor was useful for developing repair solutions under tight schedule constraints.

The $158.5 million Sarah Mildred Long (SML) bridge replacement consists of a lift bridge located on the U.S. Route 1 Bypass between Kittery, Maine, and Portsmouth, New Hampshire. Due to commercial vessel traffic in the river, large lateral loads are expected from potential vessel impact. Taking these potential loads into consideration, 10-ft diameter drilled shafts were selected for their high capacity against both vertical and lateral loadings. This paper presents the aspects of the vertical lift piers’ drilled shaft foundation designed for extreme events.

The Fort Lauderdale airport runway and taxiway expansion involved the lengthening of a 1.6-km-long landing strip into a new 2.5-km-long runway that partially sits on a 15-m-high manmade embankment, and required the construction of two substantial bridges for the runway and taxiway to traverse over US-1, Florida East Coast railway, and other airport roadways. The stringent settlement tolerances coupled with impact loading for the largest commercial aircraft, the Airbus A380, result in a design where the bridge foundations consist of approximately 2,700 driven 24-in. (61 cm) pre-stressed concrete pilings. The project design had various geotechnical considerations including avoiding differential settlement between 15-m-high MSE walls at the bridge abutments, pile group effects, and variable bearing strata. These inherent features were further complicated during construction by the dilation of dense saturated fine sands, an uncommon phenomenon for South Florida, which resulted in temporary high driving resistances and then subsequent resistance decreases after pile driving. Over 1,000 dynamic pile tests, comprising of nearly 300 test piles, and approximately 900 set-checks and/or redrives were required to ensure the project was completed safely and according to plan. The case study will provide an overview of the project and will include specific examples where both refusal conditions and dilative behavior were observed. The marriage of these conditions presented challenges in terms of driving piles to ensure that measured capacities, through dynamic pile testing, would remain higher than the designed capacity over the long term. The technical aspects of dilatancy, its impact on negative excess pore water pressure, and in turn effective stress and ultimately pile capacity, will be reviewed within the data rich environment. These aspects, among other interesting project features will be reviewed, with emphasis on the project challenges, how they were overcome, and lessons learned.

A case history is presented where a three story wood frame condominium structure was supported on piles that were driven through fill and hydrocollapsible alluvium into bedrock. The depth of fill ranged from 10.7 to 16.8 m (35–55 ft). The fill was placed over native, hydrocollapsible alluvium that ranged in depth from 0 to 7.2 m (0–23.5 ft). Design records indicated the piles were up to 29.9 m (98 ft) in length. The piles failed to prevent settlement of the structure that reached 216 mm (8.5 in.) over the last 37 years. An angular distortion ratio of 1:127 was measured, which had caused the structure to be tilted. However, the superstructure is currently free of defects that are normally associated with significant differential settlements. The original subsurface investigation report indicated the alluvium was subject to hydrocollapse potential ranging from 1.6 to 8.6%. Recent drilling indicates the alluvium is unsaturated and that the hydrocollapse process is not complete. Laboratory tests indicate that the remaining hydrocollapse potential ranges from 0.5 to 3.4%. The piles consisted of steel rails commonly used in railroad industry, resulting in long, and slender piles. These were substituted for cast-in-drilled-hole (CIDH) piles during the original design to minimize downdrag. Reasons and contributing factors to the pile failure are examined. Various modes of pile failure are analyzed and discussed. Remedial measures are considered, and pros and cons are discussed. Lessons learned from this case history are presented.

The New Jersey Turnpike Interchange 14A project involved the construction of embankments up to 34 ft in height to support twelve new roadways. Innovative ground improvement methods were needed to meet the significant challenges for the project which included: poor subsurface conditions, space constraints, existing/proposed utility constraints, an aggressive construction schedule, and the immense size of the project. A variety of ground improvement methods were utilized to limit settlements and ensure stability of the embankments. These methods included preloading with surcharge and prefabricated vertical drains, load balancing using lightweight fill, and rigid inclusions (RI). The proposed roadways were divided into six zones, based on location, subsurface condition, and embankment height. This paper focuses on the ground improvement performed in Zone 2, which consisted of concrete column rigid inclusions. The problematic subsurface conditions in Zone 2 consisted of up to a 25-ft thick layer of highly-compressible peat and organic soils without ground improvement. These soils were estimated to undergo up to 4 ft of primary consolidation settlement due to the proposed embankment loads. The design of the RIs was performed by a specialty ground improvement contractor (SGIC) using Plaxis 2D and 3D software. The performance of the Zone 2 concrete column rigid inclusion systems was verified and monitored by load tests and instrumentation. This paper presents details of the concrete column rigid inclusion design, construction, monitoring results, and lessons learned.

This paper presents the design and installation of compaction grout columns beneath four brownstone buildings through fill and organics and founded on silty sands. Grouting was carried out in three bottom up stages in two rows of inclined holes. A column diameter of 3 ft was generally achieved in the organics. Diameters in the fill were more variable ranging from 1.2 to 3.6 ft. The buildings were monitored during grout injection. During grouting of the first five holes, detectable displacements up to 0.1 ins were observed in the façade walls and up to 2 ins in a floor slab in the basement. No significant upward displacements were observed during sequential grouting in holes at twice the spacing. However, grouting adjacent holes immediately after completing a previous hole resulted in significant displacements. A 14-h waiting period between grouting operations was necessary to allow dissipation of generated pore pressures and relaxation of the soils to take place. An observational approach was adopted where injection volumes were progressively reduced when either 0.1 ins of accumulated displacement or 0.024 ins per stage has been reached.

Schedule is critical on most projects and managing geotechnical challenges and risk impacts to structures requires a team effort. As discussed in a companion paper, coastal geologies are generally not well suited for large stockpiles of material. Due to project schedule constraints, it was necessary to build a one-half mile long storage structure housing up to 15 m-high stockpiles of ore while detailed evaluation of potential ground instability was ongoing. Once the shed was erected, ground improvement to 18 m deep was needed to limit vertical and, more importantly, lateral deformations of the building foundations. This paper will review the evaluation of site conditions under large stockpile loads and the anticipated deformations. Furthermore, the paper will review the installation challenges, solutions, and instrumentation measurements completed during operation of the facility.

Three low-permeability cut-off walls were required for seepage control along the upstream toe of two new dams as part of the Lac des IIes (LDI) water management facility works. The LDI palladium mine is located 135 km North of Thunder Bay, ON, Canada. Jet grouting was used to create the low permeability cut-off walls by installing overlapping soil-cement columns. Jet grout columns were constructed using the double-fluid process. A comprehensive quality control program was implemented to ensure that specified geometric properties and performance requirements of the cut-off wall were achieved. An acoustic column inspector (ACI) tool was used to verify the diameters of the pre-production test columns. All jet grout locations were pre-drilled to prevent difficulties resulting from geological conditions and to ensure adequate penetration into bedrock. A three-dimensional profile of each jet grout column installed was generated and updated daily based on the results of pre-drill hole alignment measurements completed at every hole. In-situ permeability testing was also conducted during the pre-production test program and during the installation of the production columns. Permeability testing was performed in-situ and on cast cylinders of soil-cement samples. The low permeability cut-off walls were successfully installed and satisfied the specified performance criteria. Jet grouting was performed between the months of February and May under challenging winter conditions. This paper focusses on the quality management program (QMP) that was implemented to successfully complete this project.

Treasure Island is located in the central San Francisco Bay, immediately north of Yerba Buena Island, between the active San Andreas and Hayward faults. Treasure Island was constructed by placing hydraulic sand fill over natural shoal deposits within perimeter rock dikes. A full-scale vibro-compaction field test, using direct power compaction (DPC) was performed to evaluate the improvement potential of sandy soils susceptible to liquefaction, and to develop a site-specific DPC vibro-compaction method specification for the desired level of densification. The test was performed at a location where the soil column consisted of approximately 22–25 ft (6.7–7.6 m) of sandy, hydraulically placed fill over 23 to 25 ft (7.0–7.6 m) of natural (Pleistocene-Holocene) shoal deposits. The DPC equipment used at the test site was configured with a vibratory hammer attached to four probes consisting of H-beams modified with steel flaps hinged to the web at the base of each beam. The test program included three intensities of compaction effort and compaction with and without prefabricated vertical drains (PVD). The test site was instrumented with vibrating-wire piezometers, wireless triaxial vibration monitors, surface settlement monuments, and reflectorless robotic total-station surveys. Cone penetration test probes were advanced before and after the DPC process to characterize the subsurface conditions and to evaluate time–dependent changes in the properties of sandy fill and shoal, or aging effects. The vibro-compaction field trials, demonstrated that (1) DPC can readily densify the sandy fill using low intensity compaction effort, (2) DPC vibro-compaction with and without PVD exhibit similar increases in post-improvement penetration resistance, and no measureable changes in time-dependent penetration resistance (aging effects), and (3) the underlying shoal deposits exhibit a different response to vibro-compaction than the sandy fill. The findings of the full-scale densification testing program were incorporated in the dynamic performance evaluation of the Treasure Island shoreline, and the geotechnical ground improvement program. The dynamic behavior of the shoal was further investigated in a separate study by ENGEO.

Portland cement, blended hydraulic cement, and slag cement are all cementitious materials used in deep soil mixing, subsurface grouting, and slurry walls. Portland cement is the “default” cementitious material used in geotechnical applications due to its known properties and history of good performance. Production of Portland cement results in life cycle impacts. Blended hydraulic cement and slag cement are composed of industrial byproducts. Much of life cycle impact of these industrial byproducts has already been borne by the industries that generated them. Life cycle assessments are a means to quantify life cycle impacts and can be used to compare the relative life cycle impacts of one cementitious material or mix design to another. A material with a lower life cycle impact than another is more sustainable. For example, production of slag cement emits 14% of the amount of greenhouse gas, uses less than 1% of the amount of fresh water and recovers 145 times more renewable material than production of a like amount of Portland cement. Owners, engineers, and contractors can contribute to the sustainability of a geotechnical project by increasing the use blended hydraulic cement and slag cement in geotechnical projects while attaining the project’s performance standards. These contributions may competitively position a proposed geotechnical application or cementitious material mix design as accomplishing a more sustainable project.

A new 620-ft single-cable suspension bridge for bicycles and pedestrians was constructed south of downtown Chicago, IL to replace an aging, existing structure. The bridge spans four (4) electric railroad tracks, two (2) conventional freight railroad tracks, and eight (8) lanes of a divided highway to connect a residential area with an existing lakeside park. The bridge is founded upon five (5) separate foundations, four (4) of which are supported by drilled micropiles. Most notably, the pier foundations, near the ends of the bridge, are required to resist the large dynamic loads imposed by the suspension cable supporting the bridge deck. The pier micropiles are designed with compression and tension capacity to adjust to the varying load directions and installed with a substantial permanent pre-stress to achieve very little movement and prevent slack in the suspension cable. The remaining micropile foundations are designed to support the large vertical loads imposed by the long-span structure, including the center pylon which bears the vertical load of the suspension cable. The geotechnical exploration revealed the presence of a broad mix of urban fill, sand, silt, and clay underlain by low to medium quality dolomitic limestone bedrock. The micropiles for this project were designed to be socketed into the dolomitic limestone bedrock. The micropiles were load tested to verify the capacity and expected movement of the piles. This paper details the steps taken during design and construction to meet the performance requirements of the structure and deliver a quality product for the owner.

Hayward Baker (HB) installed macropiles and other foundation elements for the construction of a new 70-story residential development in lower Manhattan. The site is outboard of the historic shoreline of Manhattan, providing difficult geotechnical conditions that were overcome to install the foundation elements. An aggressive construction schedule required HB to mobilize multiple pieces of equipment, which were safely operated in close proximity to each other and to other contractor’s equipment. This case history will have particular focus on the design, installation, and load testing of 610 mm diameter macropiles that were over 30 m long and socketed into bedrock.

The Bronx-Whitestone Bridge carries I-678 across the East River, connecting The Bronx with Whitestone, Queens in New York City. The foundation design for both sides called for micro-piles. The soil conditions at this site presented many challenges to the foundation construction. Underlying the upper fill and/or organic layers are layers of dense silt and sand and hard clay, mixed with cobbles and boulders. To achieve the design capacity of the piles, it was necessary to drill through numerous obstructions encountered in the soil matrix. To make the project more challenging, a small settlement criterion was required for the existing bridge, and the installation of many of the micro-piles had to be performed with headroom constraints. TBTA awarded separate contracts for the construction of the Bronx approach and the Queens approach. The two contractors used different foundation construction methods. On the Bronx side, the micro-pile construction proved to be relatively successful. On the Queens side, the continuous flight auger (CFA) pile installation encountered some difficulties, necessitating remedial measures such as utilizing various means to remove/overcome obstructions, additional piles, and pile cap redesign. This paper describes the foundation design and construction for the reconstruction of the Bronx and Queens approaches for the Bronx-Whitestone Bridge, discusses and compares the different methods utilized for the pile installation for the Bronx and Queens approaches of the Bronx-Whitestone Bridge.

As Central Florida cities begin to grow and population and infrastructure webs out to support the increasing urban areas, contractors, and engineers are facing new design challenges caused by the variable and fragile karst landscapes. The greatest concern when constructing within karst terrain in Central Florida is the possibility of sinkholes (either cover-subsidence or collapse types). These isolated occurrences of drastic subsidence or soil collapse can wreak havoc on infrastructure supported on shallow foundation. Because of these hazards, proper site characterization is essential to ensure a practical, yet safe, design during construction phases, and the project’s life span. In this study, the authors develop a quantitative system of analyzing initial subsurface testing results (cone penetration tests) in efforts to provide a better understanding of the subsurface profiles and loose-soil anomalies. The resulting index, coined as the sinkhole raveling ratio (SRR), is developed through data processing and analysis of cone penetration tests (CPTs) performed in known sinkhole active sites. The SRR is a function of encountered soil resistance values, such as cone tip resistance (q_c) obtained from CPTs, as well as encountered stratigraphy thicknesses of the loose-soil anomalies. A major benefit of SRR is the ability to compare a group of CPTs within a project site or, on a larger spatial scale, between various sites exhibiting similar geological formations and soil types. Through a combination of SRR site analysis and by following the methodology presented in this study, a better characterization of potential sinkhole hazards can be performed for site development and design. Although the presented SRR index was formulated for specific Central Florida soils, similar empirical methodologies can be implemented for any site characterization in residual soils underlain by highly soluble, karst bedrocks.

Sustainability studies in geotechnical engineering have focused on life cycle assessment (LCA) of materials and construction processes to quantify the environmental and socio-economic impacts of construction. However, in the absence of a threshold or allowable value depicting the degree of sustainability, a comprehensive assessment of the system sustainability is infructuous. This paper demonstrates a framework to establish a threshold sustainability index for a geotechnical construction. The approach is illustrated through a subgrade stabilization project for a low-volume road (LVR) in Arlington, TX, involving treatment with lime and cement. The subgrade soil was an expansive (high plasticity) clay, having a low to moderate soluble sulfate concentration. The methodology incorporates a multi-criteria assessment of resource use, environmental impact, and socio-economic consequences. The framework designates the threshold sustainability index (I_T-Sus) for a particular project, besides providing a pictographic representation of the different sustainability elements.

A new three-dimensional full waveform inversion (3D FWI) method is presented for geotechnical site characterization. The method is based on a solution of 3D elastic wave equations for forward modeling to simulate wave propagation, and a cross-adjoint gradient approach for model updating to extract material property. The staggered-grid finite-difference technique is used to solve the wave equations, together with implementation of the perfectly matched layer condition for boundary truncation. The gradient is calculated from the forward and backward wavefields. Reversed-in-time displacement residuals are induced as multiple sources at all receiver locations for simulation of the backward wavefield. Seismic wavefields are acquired from geophysical testing using sensors and sources located in uniform 2D grids on the ground surface, and then inverted for extraction of 3D subsurface wave velocity structures. The capability of the presented FWI method is tested on both synthetic and field experimental datasets. The inversion results from synthetic data show the 3D FWI ability in characterizing laterally variable low- and high-velocity layers. Field experimental data were collected using 96 receivers and a propelled energy generator (PEG) to generate seismic wave energy. The field data result shows that the waveform analysis was able to delineate variable subsurface soil layers. The seismic inversion results are generally consistent with invasive standard penetration test (SPT) N-values, including identification of a low-velocity zone.

Wind turbine generators (WTGs) are typically founded on massive, octagonal, gravity-based shallow foundations composed of reinforced concrete. The foundation transfers spatially and temporally varying loads that depend on wind load, the size of the wind turbine and foundation base, and the stiffness distribution of the underlying soil. WTG foundations must withstand massive overturning moments and provide adequate bearing capacity and rotational stiffness while limiting differential settlement due to preferential wind directions. Field and laboratory testing to characterize the foundation soil response to such dynamic loads (in particular, rotational stiffness) is vital to a robust, mechanistic design approach. Two WTG foundations in the Midwest have been equipped with sensors measuring WTG tower forces and moments, and foundation and soil responses with sensors laid out to capture both vertical and horizontal stress distributions. Soil samples from each site were tested to determine their dynamic properties via a resonant column apparatus. Based on field measurements, maximum soil operational shear strains were measured to be less than 6 × 10⁻⁵ and decreased rapidly with depth. Furthermore, the soil samples’ dynamic responses are heavily dependent on the distribution of confining stress in plan and depth. That is, the added stresses caused by the WTG may result in a twofold increase in shear modulus of the foundation soil. When the results were applied to the sites’ rotational stiffness calculations, the overall stiffness of the system increased by nearly a factor of four, which would indicate that current design practice may be unnecessarily conservative.

Settlement is a critical parameter for designing foundations. Geotechnical engineers routinely struggle with overestimation of settlement of shallow foundations bearing on soft rock and stiff soil sites due to sample disturbance, resulting in unnecessary conservatism and potential underestimation of ground subsidence for sensitive soils. This paper evaluates three case histories where settlements were measured at a soft rock, a stiff alluvium, and a soft clay site. Several methods were considered to estimate the settlements. These methods included: (1) using finite element analysis based on the Winkler foundation model and subgrade modulus based on elastic properties of the subgrade, (2) Terzaghi’s traditional one-dimensional consolidation theory using laboratory tests, and (3) Terzaghi’s one-dimensional consolidation theory based on constrained modulus using CPT results. These analyses were compared with actual survey results taken during the construction to determine the most suitable method for estimating settlement in various conditions.

Over past decades, extensive research has been performed on the measurement of land subsidence as a result of compaction of aquifer. This paper describes results from a new field-monitoring system to evaluate changes in matric suction and temperature profiles in soil layers over an extended time period. The monitoring system used in this study consists of inserting dielectric sensors into a 105 m borehole, drilled in a site in Ardabil Plain, The monitoring results from the site were used to calibrate predictions from HYDRUS-1D. The physical and hydraulic properties of the soil materials in different layers were obtained through performing some soil characteristics and filter paper tests performed on soil samples. The calibrated model was then used to predict the moisture and suction profiles of the soil layers over the next 10 years. Results of this study are believed to estimate the location of the water ground and understand effects that groundwater overdraft or weather conditions may have on soil’s deformation behavior.

Increasing amounts of earth dam failures require better real-time monitoring systems to determine the changing conditions in the dams. In this study, smart acrylamide grouted sand columns with highly sensing property was developed for monitoring the simulated embankment using the changes in the electrical resistivity compared to the failure strain. With the addition of 0.1% of conductive filler (CF) made the acrylamide grouted sand a more piezoresisitive material. Just adding 0.1% CF increased the piezoresistivity of the grouted sand to over 20% at peak stress compared the compressive failure strain of 2%, make it over 10 times more sensitive. Also the addition of 0.1% CF is very cost effective. Vipulanandan stress-strain and piezoresisitive p-q models were used predict the compressive stress-strain and piezoresistivity of the smart grouted sand with varying sizes of aggregates. Also the new two-probe method was adopted to monitor the real-time changes in the piezoresisitive grouted sand. The entire grouted sand column installed in the embankment was a bulk sensor with no buried sensors. The permeability of the grouted sand was less than 10⁻¹⁰ cm/s. In order to investigate the critical locations to install the smart grouted sand columns, finite element method was used with various embankment configurations. Seepage with stability analyses were performed to quantify the changes in the shear stresses and resistivity to locate the smart piezoresistive grouted sand columns on the upstream side of the embankment and foundations. Analyzes showed the response based on resistivity was over 25 times higher than the strain.

Dams and impoundments are the most conventional method for depositing mine tailings material. Regular operation of the tailings dams often increase the height of the dams, which may make them susceptible to failure. Many existing mine tailings dams are prone to slope failure and require remediation. In this study, microbial induced calcium carbonate precipitation (MICP) is presented as a new method to improve the stability of mine tailings dams against slope failure. MICP also has the potential to improve other deficiencies of the mine tailings material such as surface erosion, static liquefaction, and dynamic liquefaction. In the present study, Slope/W program is used to perform slope stability analysis and observe the effect of MICP on the static slope stability of mine tailings material. The results show an increase in the slope stability after biocementation. The level of improvement in the factor of safety against slope failure depends on the level of treatment.

Erosion occurs when floodwalls are overtopped due to vertical free fall of water flow. In this study, a laboratory device named cutter erosion test (CET) was developed to identify the erosion rates of fine-grained soils due to floodwall overtopping. This developed test is calibrated with 15 levee-floodwall simulation tests with a 1:20 scale levee-floodwall prototype dimension and soils with various plasticity indices and compaction levels. The plasticity indices had a range from 0 to 40% and degree of compaction ranged from 70 to 90% of the maximum dry density according to standard proctor. The advantages of this device are its small size and its ability to simulate the erosion mechanism and provide estimate of erosion rates in overtopped levee-floodwall systems with soil properties such as plasticity index and compaction.