4/11/19 AEG Dinner Meeting - Newark Basin

Mesozoic Rift Basin Talk Series - Talk #4
“Case Study from the Newark Basin, NJ”
Thursday, April 11, 2019
At the Clarion Hotel in Somerset, New Jersey
 
Presented by
 
Bob Bond, P.G. - Langan


 

This meeting is sponsored by:


 

ABSTRACT
This is the final talk of the four-part series of AEG Mesozoic rift basin presentations and features a case study in the Newark Basin of New Jersey. This ongoing case involves investigating, remediating and allocating contributions for a 6,200-ft. long commingled plume, 145 acres in area, which has impacted groundwater in residential wells, surface water and structures through vapor intrusion. This presentation will refer back to the first talk in the series that highlighted Conceptual Site Models (CSMs) developed and applied in Triassic rift basin environments by discussing both plume delineation models and source area models with respect to assessing contaminant flow and transport. The horizontal and vertical extent of this case study plume is defined by the concentration of the volatile organic compound (VOC) trichloroethene (TCE) migrating through the fractured mudstones of the Livingston Member of the Passaic Formation.  However commingled groundwater contaminants include other VOCs migrating in both overburden and bedrock aquifers.  Impacted groundwater from multiple sources drain through a buried valley overburden aquifer formed over an extensional fracture system in mudstone, forming a dual aquifer plume where overburden contaminates bedrock in recharge areas and upwelling bedrock groundwater contaminates overburden in discharge areas.  The mixed plume bifurcates approximately 4,000 feet downgradient from the most upgradient sources and moves in two opposite directions; one side discharges to a stream that deeply incises bedrock and the other migrates towards a golf course supply well located 2,000 feet away from the current distal end of the plume.  Mapping the fractured pathways over thousands of feet was key to delineation and protection of receptors and for understanding the complexities of the commingled plumes.  This talk will describe the use and interpretation of intrusive methods that included coring, borehole geophysics and packer testing.  However these were limited because this mile-long plume underlies upwards of 200 residential homes.  Non-intrusive mapping of the multiple buried valleys and the bedrock fracture system was accomplished using seismic refraction, which informed the design of a minimally-sized monitoring network.  In the most upgradient source area, a bioaugmentation remedy has been implemented in both overburden and bedrock. The design basis will be discussed, which included a high-resolution mapping of the fracture network (bedding plane partings as well as steeply-dipping tectonic fractures) in the source area, as well as hydraulic conductivity and groundwater velocity data from discrete fracture zones gathered from tracer studies. This case illustrates the importance of understanding complex groundwater flow regimes and applying CSMs at different scales.

BIOGRAPHY
Bob Bond, P.G. is a consulting senior hydrogeologist with Langan in Doylestown, PA.  He has over 31 years of environmental assessment and remediation experience and holds a B.S. Degree in Geology from Allegheny College and an M.S. Degree in Geology from Lehigh University.  Bob’s practice focuses on the hydrogeologic assessment and remediation of fractured bedrock aquifers impacted by suites of chlorinated solvents.  He has designed, implemented and managed numerous hydrogeologic and remedial investigations using his background in geochemistry and structural geology to model the fate and transport of contaminants.  Bob has served on five Interstate Technology and Regulatory Council (ITRC) teams, and has a history of yearly involvement and responsibilities with national conferences, including Battelle, National Ground Water Association (NGWA), and the Geological Society of America (GSA).  He has taught university short courses and spoken at local and national conferences on environmental forensics, data analysis, fractured bedrock assessments, and the fate and transport of contaminants.