AEG KARST HAZARDS FORUM
Recent Advancements in Karst & Karst-Like Hazards’ Investigation and Mitigation
Forum schedule coming soon!
The days and possibly concurrent sessions each day will be divided by the major themes of General, Karst, Pseudokarst, and Anthropogenic Sinkholes.
Sessions may be separated by the following topics or their adjustments: Geologic Environs, Investigation/Mapping, Geophysics/Remote Sensing, Hazard/Use Categories, Risk of the Hazard, Mitigation of the Hazard, Public Information/Protection, and Case Histories.
(10 additional invited speakers will be added as their abstracts are received)
Geophysical Imaging in Karst Terrain in Proximity to Intermittent and Perennial Streams
Neil Anderson, Missouri S&T
Electrical resistivity tomography (ERT) and multichannel analysis of surface waves (MASW) data were acquired along relatively dense grids of traverses at two work sites. At the first work site, in greater St. Louis MO, geophysical data were acquired in support of an effort to identify seepage pathways beneath an earth-fill dam. Based on the assessment of the acquired geophysical, trench and borehole control, it was concluded that the dam was constructed on bedrock that was most intensely karsted beneath the original perennial stream channel. Prominent seepage pathways beneath the dam were identified. At the second work site, in Springfield MO, geophysical and borehole data were acquired in proximity to and across acreage under consideration as the site for a new fly ash landfill. Not surprisingly, bedrock in the area surveyed, was most intensely karsted beneath perennial and intermittent stream channels. Most of the active karst features in proximity to the work site appear to have developed along perennial or intermittent stream channels either naturally or as the result of anthropogenic activity.
Neil Anderson is professor emeritus (geological engineering program, Missouri University of Science & Technology) and a consultant to industry. Neil‚Äôs primary area of specialization is shallow geophysical imaging (engineering geophysics). He has acquired, processed and interpreted geophysical imaging data in support of geological and geotechnical site characterizations (frequently in karst terrain), bridge deck and pavement assessments, archeological and hydrologic investigations, and utility detection.
Geophysics in Karst; What Works, What Doesn't, and Why
Timothy Bechtel, Ph.D., PG, Franklin & Marshall College/RETTEW Associates, Inc.
Subsurface heterogeneity is characteristic of karst, making extrapolation of data, or correlations between boreholes, suspect. In many terranes, this can be mitigated using geophysical data to constrain subsurface properties away from borings or other ground truth. This is true, and particularly valuable in karst, but particular geophysical methods must be chosen carefully, with survey parameters adjusted for particular settings and survey goals. This presentation will review the basic physics of the three methods most suitable for characterizing karst features -microgravity, seismic, and electrical resistivity - and present examples (both successful and unsuccessful) to illustrate their capabilities, limitations, and trade-offs when applied to detection and characterization of subsurface karst features.
Tim grew up on the highly-karstified Rockdale Run Formation. He has BSc, MSc degrees in geology, and a PhD in geophysics. He has taught Geophysics, Karst Hydrogeology, Geocomputation, Engineering Geology, and Environmental Geology at Franklin & Marshall College, and UPenn. Tim is an Associate Editor for the Journal of Sensing and Imaging, and Hydrogeology, and a member of the Karst Commission of the International Association of Hydrogeologists. He does consulting as the Senior Geophysicist for RETTEW Associates, Inc., and research as a member of international collaborations funded by NATO‚Äôs Science for Peace and Security program, and the US-Russia-Japan-EU International Science and Technology Center. Topics include technologies for humanitarian de-mining, non-destructive testing for cultural preservation, and karst hydrogeophysics. He now lives on the mildly-karstified Conestoga Formation.
Multimodal and Spatial Assessment for Investigation of Karst Risk
Michael Byle, Tetra Tech, Inc.
Karst conditions pose risks for various types of development and vice versa. The complicated and unpredictable nature of karst conditions limit the effectiveness of many investigation approaches, requiring site specific approaches to investigation. The presentation will present a synopsis of methods of investigation that have been successfully used and the conditions in which they are used. Data collection methods including digital aerial imagery, borehole geophysics, 3-D modeling, multiple types of surface geophysics, borehole dye tracing, borings and test excavations will be described. The presentation will include discussion of the basis and applicability of the methods and examples of their use.
Mr. Byle has more than 39 years of professional experience in civil and geotechnical engineering, Mr. Byle’s experience includes work on both terrestrial and marine projects, investigations, studies, and design. His background includes extensive experience in investigation and rehabilitation of structures and foundations, soil improvement techniques, grouting, stormwater management including infiltration and Best Management Practices (BMPs), exploration and mitigation design for karst, and project management for civil, geotechnical and geo-environmental projects. Expert consultation experience includes specialty areas of grouting, karst, foundation rehabilitation and restoration, NPDES and mining permit appeals in location around the world. He has served on an international board of consultants, chaired international conferences on karst and grouting and is a member of the ASTM D18.27 on karst.
Implementation of the Karst Survey, Remediation and Conservation Plan for a Natural Gas Pipeline Project
Robert K. Denton Jr., CPG, LPSS, GeoConcepts Engineering Inc., a Terracon Company, Ashburn VA
In 2015 Columbia Gas/TC Energy proposed to construct and operate 29.2 miles of various diameter pipelines in Virginia and West Virginia. Due to the potential impact of construction activities on the karst resource, in particular the karst aquifer, a karst survey, resource conservation, and remediation plan (“Karst Plan”) was developed. This plan was reviewed and approved by Federal and State regulators, and was implemented during the project’s construction phase. Karst Specialists were engaged to monitor karst remediation activities during construction, and provided training for the project environmental inspectors. The pre-preconstruction karst survey phase identified 25 karst features occurring within and/or receiving drainage from the Limits of Disturbance (LOD) of the proposed right of way and access roads. Features included sinkholes, losing streams, swallets, and 2 caves that could be potentially impacted by construction. Each feature was described in detail, and located using sub-meter accuracy GPS equipment. Terracon’s karst specialists then worked with the project engineers and environmental consultants to develop customized protection measures for each feature with an emphasis on avoidance and minimization of impact. The project was brought to a successful completion in 2019, and the karst management effort has been successful in preventing impacts, and the entire alignment within karst terrain will be reinspected at 1, 2, and 5 years post construction in accord with the Karst Plan that was approved by Federal and State regulators.
Robert K. (“Bob”) Denton Jr. was born in 1953 in Montclair, New Jersey. He received his Bachelors Degree in Natural Science from Thomas Edison State College in Trenton, NJ in 1988. Bob worked as a research scientist in the chemical and medical device industries for over 20 years, specializing in physical methods of analysis. He relocated to Winchester, Virginia in 1995, and is currently a senior geologist and karst geology “Subject Matter Expert” (SME) with Terracon’s DC Metro office, located in Ashburn, VA. His specialties include environmental science, engineering geology, hydrogeology, and karst characterization, remediation and management. He is considered a national expert on stormwater management in karst terrains.
Mapping Karst Across the United States: A Review and Update
Daniel H. Doctor, Ph.D., U.S. Geological Survey
A variety of karst types exist throughout the United States, and each karst region presents a unique set of challenges for geological engineering. Ground stability hazards such as sinkholes and shrink-swell soils are commonly encountered in karst areas, but just as challenging are issues of stormwater management, water well development and disposal of fluid wastes. Karst development is influenced by factors such as bedrock type, surficial cover, geologic structure, and local hydrogeologic conditions. Mapping and classification of different karst types can provide information on how best to approach an engineering project in a particular karst setting. The U.S. Geological Survey has periodically produced maps of regions prone to karst development. In 1984, the “Engineering Aspects of Karst” map of the U.S. was published based on the early compilation work by William E. Davies and others. In 2014, a digital database of karst regions was released depicting the extent of known karst, potential karst, and pseudokarst areas of the United States of America including Puerto Rico and the U.S. Virgin Islands. The geospatial database represents soluble rock types (carbonates and evaporites), and rocks with physical properties conducive to the formation of pseudokarst features such as lava tubes, piping features, and thermokarst. The geospatial data show that approximately 18% of the surface of the United States is underlain by soluble bedrock with potential for karst features. Recent work has been conducted to map the density of large closed depressions in karst areas within the conterminous U.S. to help identify areas that are most susceptible to sinkholes. Together, these maps and digital data provide valuable tools for understanding the potential for encountering karst features in engineering projects.
Dan Doctor is a research geologist with the U.S. Geological Survey specializing in the study of karst regions. His research interests include the hydrology and geochemistry of karst aquifers, the assessment of sinkhole hazards, the evolution of karst landscapes, and the generation of paleoclimate records from karst areas. Dan holds a B.A. in Geology from Colgate University, and a Ph.D. in Hydrogeology from the University of Minnesota with a doctoral minor in Water Resources. Dan is a fellow of the Cave Research Foundation, has served on the board of the Karst Waters Institute (KWI), and was appointed by the Governor of Virginia to the Virginia Cave Board.
Explosive and Toxic Vapors in the Vadose Zones of Karst Flow Systems: Case Studies and Ongoing Concerns
Chris Groves, Ph.D., and Nick Crawford, Crawford Hydrology Lab, Department of Earth, Environmental, and Atmospheric Sciences, Western Kentucky University
The often-high permeability of karst aquifer systems can allow rapid movement not only of water and contaminants, but also air and other gasses in the vadose zone. These may include explosive or toxic vapors. While the physics of airflow have been studied in explorable caves and shown to be driven by forces resulting from pressure and density variations, gasses may also move through an extensive network of smaller, unexplorable spaces that can permeate regions of the vadose zone. Serious environmental problems—including human health, ecological, and economic—have resulted from contamination of underground air in the unsaturated zones of karst systems. For example, in 1966 an explorer’s lamp set off a “blinding explosion” of leaked gasoline fumes in Howard’s Waterfall Cave in Georgia leaving one explorer dead and another critically burned. Two would-be rescuers also died. Another explorer had been killed in a similar explosion in New Mexico’s Cable Cave in 1951. Gasoline fumes also permeated the karst unsaturated zone beneath Bowling Green Kentucky in the 1980’s causing evacuation of homes, businesses and schools “on the grounds that explosive levels of fumes existed, and that detectable levels of benzene, toluene, and xylene exceeded standards for ‘non-occupational settings.’” Economic losses occurred when Missouri’s tourist cave Meramac Caverns was closed for a time in 2016 due to health and safety concerns from Trichloroethylene (TCE) fumes that had come laterally through the unsaturated zone for more than six kilometers from a Superfund site. In these cases, gas moved through unsaturated zones in response to natural forces and associated gradients. In contrast, large high-pressure natural gas pipelines under construction in highly karstified areas of the Appalachian Mountains are designed to operate far above atmospheric pressures, and little is known about the impacts of gas in karst unsaturated zones under such forced pressure gradients.
Chris Groves is University Distinguished Professor of Hydrogeology at Western Kentucky University where he directs the Crawford Hydrology Lab. He received a PhD in Environmental Sciences at the University of Virginia in 1993, developing an active international research program in hydrogeology, geochemistry and water resources, with fieldwork in 25 countries. In 2017 Groves received China’s highest award for foreign scientists from President Xi Jinping for “great contributions to China’s hydrogeology and karst geology fields.” Groves serves on several karst-related United Nations scientific programs, including the Governing Board of UNESCO’s International Research Center on Karst. He has served as an Associate Editor for Journal of Hydrology and Hydrogeology Journal, and has published in leading journals, including Groundwater, Water Resources Research, Journal of Hydrology, and Geomorphology.
Quantitative Tools for Assessing Feasibility and Designing of Groundwater Remediation in Karst
Neven Kresic, PhD, PG, Geosyntec Consultants, Inc.
Characterization of groundwater flow, and fate and transport of contaminants in karst is notoriously difficult due to the specific nature of karst porous media and presence of various dissolution features: voids, cavities (‚Äúconduits‚Äù) and similar. It is even more difficult to evaluate, quantitatively, if proposed groundwater remediation measures at a contaminated site are cost-effective, can be guaranteed to reduce the risk to human health and the environment to acceptable regulatory levels, or if they are even feasible. Notwithstanding the fact that every single (or important) karst feature at the Site, regardless of the scale of the problem, (i.e., the horizontal and vertical extent of contamination) may never be accounted for, it is possible to reasonably accurately assess these inherent uncertainties using adequate numeric modeling tools. This presentation discusses disadvantages of modeling based on traditional porous media approaches and Darcy‚Äôs Law, such as classic MODFLOW. In contrast, using examples, a discussion will be provided on a new generation of models that have adequate numeric tools for simulating simultaneously the complexities of karst groundwater flow in all porous media present, in a physically (hydrogeologically) defensible way. One such recent numeric model in public domain is MODFLOW USG (for UnStrucuredGrids). Due to full coupling of the system of equations and the interactions between different types of porous media, within a flexible gridding framework that allows these domains to be discretized independently of each other, it eliminates the need for various surrogate modeling approaches in karst. The significant features that enhance simulations in karst environments include various optional turbulent flow formulations (e.g., for karst conduits), solute contaminant transport capability in both the karst features and the rock matrix, in vadose and saturated zones, and a density-dependent flow simulation option which can be used to model transport of non-aqueous phase liquids (NAPLs) for example.
Neven Kresic, PhD, PG, is Senior Consultant in Geosyntec‚ Washington, DC. Office. He has over 30 years of consulting, research, and teaching experience, including major projects in the United States and internationally. Neven worked for various clients, including regulatory agencies; industries such as water, transportation, and power utilities; and oil, petrochemical, chemical, and mining companies. He was Senior Fulbright Scholar at the USGS in Reston, Virginia, and the George Washington University, Washington, D.C., where he conducted research on modeling of flow, and contaminant fate and transport in fractured rock and karst aquifers. Neven has authored numerous scientific and professional papers and presented at various national and international conferences. He authored seven books including Water in Karst; Management, Vulnerability and Restoration by McGraw Hill (2013).
Geotechnical Engineering in Karst: Lessons Learned from Case Histories
Walter Kutschke, PhD, PE, DiGioia Gray and Associates
Karst is a unique challenge for geotechnical engineers. Case histories involving roadway, pipeline and building projects approaching $1 billion in construction costs demonstrate the challenges and successes of geotechnical engineering over karst. Experience gained from these projects all had a common theme ‚Äì water controls everything in karst. Engineering efforts need to consider this basic karst principle before undertaking any meaningful design. Geotechnical site characterization activities for karst typically involve test borings and / or geophysical methods. Although these methods provide a valuable snap-shot in time of subsurface conditions, karst is a dynamic environment and these methods do not characterize changes over time, such as groundwater fluctuations. While the karst hydrogeologic regime is complex and developed over geologic time, sinkhole formation is relatively straightforward with development that can occur in a sudden and erratic manner. Geotechnical site characterization efforts must consider known sinkhole triggers as well as sinkhole occurrence rates. Another aspect of karst often overlooked by engineers is that sinkholes are direct input points where surface water can access the karst aquifer and impact water quality and hibernacula of cave dwelling species. Several case histories indicate the detrimental impact of altering subsurface water conditions which can result in increased subsurface erosion and new sinkhole development. Case histories also underscore the importance of controlling surface water and when not properly considered, the result can be sudden and catastrophic sinkhole development. Although every karst site is unique, lessons learned from review of case histories all have a commonality, that being water. Spend your effort understanding this basic karst principle to properly address the engineering challenges of karst.
Walter G. Kutschke, PhD, PE is the Geosciences and Civil Engineering Service Line Manager for DiGioia Gray and Associates. Dr. Kutschke has been involved with greenfield, remediation, forensic, and expert witness karst projects with an aggregate construction cost of nearly $1 billion. He has over 26 years of geotechnical design and specialty geotechnical construction experience, and is licensed as a Professional Engineer in seven states. He can be reached at email@example.com.
Karst and the Law: The Expert Witness as Educator
Jesse Richardson, West Virginia University
Courts struggle to deal with evidence relating to the existence of karst terrain and the impact of human activities on karst terrain. Although courts often must hear cases involving complex scientific issues, karst seems to prove especially problematic, perhaps because of the lack of uniformity and the site-specific nature of the resource. This presentation analyzes published opinions involving courts analyzing expert testimony as to karst matters. Analysis of the court cases indicate that courts are generally ill-equipped to deal with expert testimony related to karst matters and that this testimony may prove to be more problematic than other technical, scientific evidence due to the nature of karst as a heterogeneous resource depending upon site-specific studies and examination. The presentation takes lessons learned from the courtroom to develop guidelines for technical experts to be more effective expert witnesses. The presenter recommends that the scientific karst community further educate lawyers, judges and citizens on the scientific aspects of karst, including the heterogeneous nature of karst. Ultimately, however, expert witnesses in karst matters should incorporate education of the court, attorneys and juries into their reports and testimony, to the extent that the court allows. The education component forms an essential part of the role of the expert witness as team member in karst litigation.
Jesse J. Richardson, Jr. is a Professor of Law and the Lead Land Use Attorney at the Land Use and Sustainable Development Law Clinic at the West Virginia University College of Law. Mr. Richardson is a former member of the Board of Directors of the National Cave and Karst Research Institute and the Virginia Cave Board He was honored with the 1999 Professional Scholarship Award from the American Agricultural Law Association, the 2004 William E. Wine Award for a history of teaching Excellence from Virginia Tech (the highest teaching award granted by the university), and the 2009 University Certificate of Excellence in Outreach.
A Multi-Geophysical Case Study of a Karstic Aquifer
Mustafa Saribudak, Ph.D., Environmental Geophysics Associates (EGA)
Barton Springs is a major discharge site for the Barton Springs Segment of the Edwards Aquifer and is located in Austin. Barton Springs actually consists of at least four springs. Main Barton Springs discharges into the Barton Springs pool from the Barton Springs fault. Surface geophysical surveys [resistivity imaging, induced polarization (IP), self-potential (SP), seismic refraction, and ground penetrating radar (GPR)] were performed across the Barton Springs fault and Main Barton Springs during the years of 2012 and 2013. The purpose of the surveys was two-fold: 1) locate the precise location of submerged conduits (caves, voids) carrying flow to Main Barton Springs; and 2) characterize the geophysical signatures of the fault. Geophysical results indicate significant anomalies to the south of the Barton Springs pool. A majority of these anomalies indicate a fault-like pattern, in front of the south entrance to the swimming pool. In addition, resistivity and SP results, in particular, suggest presence of a large conduit in in the southern part of the Barton Springs pool. The groundwater flow-path to the Main Barton Springs could follow the locations of those resistivity and SP anomalies along the newly discovered fault. Since the geophysical work done, in December 2019, Main Barton Spring started discharging plumes of turbidity flows into the Barton Springs swimming pool (BSSP). Within a couple of days, the source was found to be a geothermal drilling site at a residential neighborhood, which is located about 4,000 ft to the southwest of the pool. During the drilling operation ten closed-loop geothermal wells were drilled into the karstic Edwards Aquifer. A report concluded that a void was encountered at a depth of 240 ft, and was likely connected to a karst conduit flowing to the BSSP. The estimated pathway corresponds to the geophysical anomalies to the south of the BSSP.
Mustafa Saribudak is the principal of Environmental Geophysics Associates (EGA). He holds a Master's in geology from the University of Istanbul and a PhD in geophysics from the Istanbul Technical University (ITU) in Turkey. He worked at ITU for a year as assistant professor. He then came to the University of Houston in 1990 as a visiting geoscientist. He founded EGA in 1994 to provide near-surface geophysical services for engineering, environmental, and oil and gas industries, and real estate developers. During the last 26 years he has conducted many geophysical surveys successfully in the U.S., Central and South America, and Canada. He has published numerous papers and short notes in geophysical and environmental journals. He lives in Austin.
Processes and Problems in Sandstone Karst
Ira D. Sasowsky, Ph.D., University of Akron; Alexander, E. Calvin, Jr.; University of Minnesota
Hazards of karst terranes include land collapse, flooding, and groundwater contamination. These occur by rapid transport of water, regolith, and contaminants through rock openings. Such openings may exist in siliciclastic sandstone terranes; there are geotechnical and environmental ramifications of these conditions. In northeast Ohio there are many sinkholes in sandstones, with a variety of morphologies, commonly cover subsidence. Mechanical as well as chemical processes are in effect. In Minnesota hundreds of small sinkholes are known. In tropical situations, such as the tepuis of Venezuela, large collapse sinkholes (up to 300 m depth) and swallets are found in quartzite. Great landscape age, high water volumes, and/or high hydraulic gradients are required for formation of these features in sandstone. Numerous cases of geotechnical and environmental problems are known from Minnesota’s Ordovician St. Peter Sandstone and New Richmond Sandstone, and in the Precambrian Hinckley Sandstone. These sinkholes provide direct, fast pathways for surface pollutants to reach aquifers. Engineered structures have induced new sinkholes to form. Wastewater treatment lagoons on the New Richmond Sandstone failed when new sinkholes opened and drained sewage into the underlying aquifers. Major stormwater retention structures have failed due to catastrophic sinkhole development. New irrigation wells induced a cluster of sinkholes to develop in the St. Peter Sandstone. Broberg documents numerous large voids in the St. Peter Sandstone under the city of Rochester, MN during excavations, significantly impacting the geoengineering of major building foundations. Two major caves in the same unit exist under Minneapolis, both of which were discovered during excavation of storm sewer tunnels. All of these cases emphasize that “karst-like” processes can operate in rocks that we normally consider to be poorly soluble. As a consequence, rapid groundwater movement and its environmental ramifications, as well as the potential for collapses, must be considered in a variety of environments.
Dr. Sasowsky is Professor of Geosciences at University of Akron, where he teaches courses in hydrogeology, geomorphology, and other topics. His research focuses on land-water linkages in karst terranes. An elected Fellow of Geological Society of America, and the National Speleological Society, he lectures worldwide on karst-related topics.
State of Art and Challenges of Karst Groundwater use at Global Scale
Zoran Stevanovic, University of Belgrade-Faculty of Mining & Geology, Centre for Karst Hydrogeology
Karst aquifers are one of the main water sources used in the world. The WOKAM (World Karst Aquifer Map) project indicated that different types of karstified rocks crop out over approximately 15% of ice-free land. The countries with more than 1 x 106 km2 of karst surface, are: Russia, USA, China and Canada. Globally, 1.18 billion people or 16.5% of the global population live on karst, but an assessment for 2016 indicates that just around one-half of them (9.2%) use karst water for drinking purpose. The biggest karst waters consumer is China. It is estimated that approximately 150,000,000 Chinese citizens depend solely on the utilization of karst aquifers. The second largest consumer is the USA where is roughly estimated that about 50 million people, mostly from sparsely populated areas, depend on karst waters. More than 10 million people also dominantly using karst waters in Iran, Mexico, Indonesia, Russia, France, India, Philippines, Turkey and Italy. In principle, karstic rocks and aquifer systems provide the largest springs and they are widely utilized as a source of drinking water supply, much more than well fields or other type of water tapping structures. With a total estimated withdrawal of 127 km3/year, karst aquifers are contributing to the total global groundwater withdrawal by about 13%. However, only around 4% of the estimated average global annually renewable karstic groundwater is currently utilized, of which < 1% is for drinking purposes. Karst aquifers are vulnerable to climate variations and low-water seasons often result with water shortage in communal water systems. Although problematic because of unstable discharge regimes and high vulnerability to pollution, in many countries and regions karst groundwater represents the main source of potable water supply. However, engineering solutions are often required to ensure sustainable water supply and prevent negative consequences of groundwater over-extraction.
Professor and Head of the Centre for Karst Hydrogeology at the Department of Hydrogeology of the University of Belgrade - Faculty of Mining & Geology, Belgrade, Serbia. Vast experience in implementation of groundwater management projects (Algeria, Iraq, Georgia, Bhutan, Seychelles, Somalia, Ethiopia, and Balkans countries). Consultant of the FAO and UNESCO. Co-Chair of the Karst Commission of IAH and the Vice Chair of the Board on Karst and Speleology of the Serbian Academy of Science and Arts. Past-President of the Serbian Geological Society and founder and Chairman of its Karst Commission. Member of the Scientific Society of Serbia and Corresponding member of the Academy of Engineering Sciences of Serbia. Honorary member of the Hungarian Geological Society and member of the Bulgarian Geological Society.