Monthly Luncheon With Guest Speaker Jeff Nuttall

10/11/2018 @ 11:30 am – 1:00 pm

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Date(s) - 10/11/2018
11:30 am - 1:00 pm

Wynkoop Brewery

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October 11, 2018


Located At Wynkoop Brewery

1634 18th Street in Denver




Subsidence Risk Characterization – Integrating Hi-Res Shallow 3D Seismic into Site Investigations (from a geologist’s point of view)




In regions with extractive mining activities or karsting, critical infrastructure must be engineered to manage ongoing ground deformation (e.g. mine collapse, sinkholes) and stresses induced from subsidence over time. Identifying and characterizing subsidence-prone areas with respect to existing and planned infrastructure is key to informing engineering approaches to safely manage the associated risks. Integrated site characterization using advances in seismic imaging technology provides comprehensive site data that geologists, engineers, and geophysicists use to generate high-resolution 3D site models to constrain subsidence magnitudes and rates. For example, subsurface coal mine collapse conditions vary widely based on the style of mining (longwall, retreat, room and pillar, extent of pillar robbing, type of entryway supports, age of workings, gob conditions, and seam thickness). As historic workings are mostly inaccessible, shallow high-resolution 3D seismic can successfully image void locations and extents, upward propagating fractures, and groundwater conditions using non-invasive data acquisition technology from the ground surface. The resulting seismic imaging data inform remediation and up-front engineering design for planned infrastructure to mitigate subsidence risks over the project lifespan (e.g. pipelines, powerplant foundations, bridges). Performing these integrated site characterization surveys in areas with historic mining or karsting up-front in a project lifecycle can result in significant project savings and prevent delays in construction and permitting.  A custom, modular, integrated seismic acquisition design combined with multiple processing approaches can adapt to a range of subsurface conditions, often poorly constrained prior to seismic imaging. Initial seismic survey locations are targeted based on existing infrastructure and planned infrastructure alignments, historic mine maps, CAD files of underground workings, borehole data, LiDAR and satellite imagery, and geomorphic features. Current technologies allow for high-resolution geophysical imaging to be integral in geotechnical investigations of subsidence, furthering the understanding of risk to critical infrastructure.



Jeffrey Nuttall, P.G. joined Tetra Tech in 2004 and currently serves as an Abandoned Mine Lands Program Manager for the Rocky Mountain Region.  In this role he leads a team of geologists, engineers, and geophysicists who perform high-resolution integrated site characterizations, abandoned underground coal mine fire investigations, subsidence risk evaluations and mitigation in areas affected by historic underground mines and karst geology. Project experience includes project management, site layout, soil sampling, borehole logging, cavity scanning, piezometer/monitor well installation, groundwater monitoring, hydrogeological testing, remote sensing, thermal imaging, geophysical methods, data evaluation, subsidence risk evaluations, UAV data collection, 3D modeling and reporting.  Ongoing projects include subsidence risk evaluations for critical infrastructure, underground coal mine fire investigations and remediation.  He is registered as a Professional Geologist in Wyoming.




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