Synopsis: Many traditional site investigation methods have been replaced in recent years by high-resolution site characterization tools that are designed for deployment
using direct push boring advancement techniques, but there are penetration
depth and other practical limitations to those technologies. Nuclear Magnetic
Resonance (NMR) geophysical tools are now available for near surface and
shallow aquifer characterization using technologies first developed for use in
the oil and gas industry. NMR logging provides high-resolution quantification
of porosity (both mobile and bound water fractions) and hydraulic conductivity,
and can detect and quantify multi-phase saturations of certain LNAPLs. NMR data
can be acquired through non-metallic (PVC) casing using existing well
infrastructure eliminating the need for additional invasive borings required
with other technologies. NMR is a proven technology that will provide
high-resolution data of critical aquifer properties required for conceptual
site models and for remedial system design and optimization, particularly at
legacy sites where progress toward site closure has stalled.
Case studies will be presented that demonstrate the viability of using NMR technology for near-surface investigations in both alluvium and bedrock settings. Continuous,
high-resolution vertical profiles of total porosity, mobile, capillary bound and clay bound porosity fractions, and hydraulic conductivity collected from existing PVC-cased monitoring wells will demonstrate how NMR data can be used to develop a robust CSM, provide input to groundwater flow models, and help optimize groundwater extraction wells and remediation systems. Examples of LNAPL saturation detection and quantification will also be presented.
Speaker: Bradley D. Cross, R.G., P.G. is a Principal Hydrogeologist and Technical Expert at ERM with
over 35 years of experience in environmental consulting, water resources, and
petroleum exploration. Specific areas of expertise include stratigraphy &
sedimentology, hydrogeology, geophysics, and high-resolution site
characterization. He holds a B.S. in Geology from Colorado State University and
an M.S. in Geology from Texas A&M University.
For the past 10 years, Mr. Cross has been a pioneer in the application of nuclear magnetic resonance (NMR) geophysics to the environmental
industry. He has worked with both regulators and industry, and has implemented
numerous NMR investigations at sites across North America in a variety of
geologic settings.
Date: Tuesday, January 19, 2021
Time: 12 noon to 1:00 p.m.
Where: Zoom link will be sent by e-mail to those on our list; e-mail events@sacpema.com to request the Zoom link