Geotechnical Engineering

CMT has a deep bench of talented geotechnical engineers with decades of experience in challenging soil and geologic environments. Our geotechnical staff, which is licensed in PA, OH, MD, WV, and VA, perform the following services:

Author Geotechnical Reports
Conduct Slope Stability Investigations
Conduct Forensic Investigations

Design Geo-Structural Systems
- Deep Foundations
- Temporary and Permanent Shoring Walls

Our staff also has unique experience with karst (limestone and dolomite bedrock) features such as closed depressions and sinkholes as well as a wealth of knowledge in testing and evaluating expansive pyritic bedrock.

Geotechnical Reports

Our talented staff has combined to author over 1,000 geotechnical reports in a variety of geologic settings. We have conducted investigations in various settings:

Karst Topography
Mine-Out Bituminous and Anthracite Coal Regions

Glacial/Marine/Residual/Alluvial Soils
Expansive Pyritic Bedrock Lithology

Our reports have been conducted across a vast array of project types and clients, including:

Residential, Educational, Commercial, and Industrial Buildings
Roadways and Bridges
Water and Wastewater Treatment Facilities

Utilities: Substations and Transmission Lines
Horizontal Directional Drilling (HDD) Projects
- o Hydraulic Fracturing Analysis of drilling Fluids

Geo-Structural Design

CMT provides a wide variety of design services for below grade structures, such as deep foundations (drilled piers, micropiles, driven piles, etc.), soil nail walls, and soldier pile walls (tie-back and cantilever). We have extensive experience in designing micropiles in challenging karst geology.

Slope Stability Investigations

CMT provides geotechnical reports that focus on complex slope stability conditions such as roadway embankments, large fill slopes, flood control fill embankments, and large cut/fill drilling pads. We have directed the installation and monitoring of slope inclinometers and perform strength and permeability testing of soils in our advanced soils lab. We also provide forensic and expert witness services for large land movement cases.

Sinkhole Investigations

CMT’s office is located in the Valley and Ridge Province of Pennsylvania, which has a complex karst geologic topography and ubiquitous sinkholes. Our engineers and soil scientists are frequently providing sinkhole related investigations and repair recommendations. We utilize various techniques to investigate existing sinkholes and the potential for sinkholes, such as test pits, test borings, and geophysical (EI) surveys.

CMT utilizes a 56 electrode AGI Supersting R8/IP/SP Resistivity Meter to investigate karst topography. Electrical resistivity surveying is a nondestructive method of characterizing the subsurface resistivity distribution by introducing a current into the subsurface and measuring the resulting voltage potential field via electrodes. It is based on the principle that the distribution of electrical potential around a current-carrying electrode is dependent on the electrical resistivity and geometry of the surrounding soils and rocks through which the current passes. Electrial Imaging (EI) can aid in detecting anomalies in the subsurface that could be linked to voids or soil filled cavities in the carbonate bedrock. CMT utilizes EI to supplement “ground truth” data such as from test borings and/or test pits to determine risk.

CLICK HERE to check out our technical paper published in Geostrata that outlines our role in investigating and developing repair recommendations for a large sinkhole in Central Pennsylvania.

Specialty Field Testing Services

Obtaining the appropriate geotechnical data is not always straight forward and easy, especially when access is limited. CMT specializes in challenging circumstances and utilizes the following methods to obtain the necessary information to complete a thorough investigation:

Dual Mass Dynamic Cone Penetrometer (Bearing Capacity and CBR)
Split-Spoon and Shelby Tube Hand Sampler (SPT and Undisturbed Sampling)
Hand Operated Vane Shear Tester (Shear Strength)

Concrete Coring Rig (Access)
Deep Foundation Load Test Documentation and Analysis

Pyritic Bedrock Investigations

Bedrock containing pyrite or “fools gold” (FeS2), particularly in dark gray to black shale, can be potentially expansive due to the formation of hydrous sulfates (gypsum, melanterite, halotrichite, etc.). The geochemical process is very complex; however, it essentially involves the oxidation of pyritic, the formation of sulfuric acid, and the precipitation of sulfate upon the interaction of the acid with other minerals in the rock such as calcium carbonate. CMT is at the leading edge of the technology to identify and test for this phenomenon. We have been investigating and testing pyritic bedrock for 25+ years.

Check out our research and technical papers published in various journals and conference proceedings:

GEOTECHNICAL
ENGINEERING