Use of Electrical Resistivity Profiling to Reduce Landfill Siting Risks in the South Central Kentucky Karst

doi:10.21203/rs.3.rs-4797501/v1

Download PDF

Research Article

Use of Electrical Resistivity Profiling to Reduce Landfill Siting Risks in the South Central Kentucky Karst

https://doi.org/10.21203/rs.3.rs-4797501/v1

This work is licensed under a CC BY 4.0 License

You are reading this latest preprint version

Electrical Resistivity (ER) can be a key tool for aiding in characterization of karst geohazard risks at proposed landfill sites. This focused study is proximal to the south central Kentucky karst and Mammoth Cave National Park and possesses siliciclastic cap rock upland areas that pose relatively high groundwater-contamination risks due to adjacent ravines floored by carbonates. Complex stratigraphy associated with the Mississippian-Pennsylvanian unconformity and juxtaposition of heterolithic sedimentary rocks in general presents further challenges for demarcating hydrogeological characterization of the base of engineered landfills. A conceptual site model integrates ER surveying and field geology that both satisfactorily characterize the site and risks to groundwater resources without conducting multiple borings. Our work entails two ER profiles that traversed the site, study of outcrops, an excavated pit and trench and briefly compares the focus study area to regional sites with caves. ER data range from several low 10s to about 400 ohm-meter values for mud rock units whereas sandy units possess ER values from approximately 500 to several 10 tens of thousands of ohm meters. The greatest values are indicative of basal Pennsylvanian Caseyville Sandstone and these exceed 32,000 ohm meters. An unexpected challenge specific to this study includes occurrence of well-drained and highly weathered Caseyville at the highest elevations of the site where electrical contact was not possible during ER surveying. The overall ER contrast however, between quartz-rich and clay poor strata (high-resistivity rocks) and clay-rich strata (low-resistivity rocks) provides independent data consistent with the observed stratigraphy exposed in site exposures.

Electrical Resistivity

Karst

Kentucky

Mammoth Cave

Landfill Siting

This study was initiated as part of a geological assessment of a proposed construction and demolition debris (CDD) landfill site located on Chestnut Grove Cemetery Road near Bonnieville, Kentucky (Hart County) as required by the Kentucky Division of Waste Management (DWM), Solid Waste Branch to assess groundwater contamination risks (Figure 1). Note especially the location of Bowling Green, the fastest growing urban area in Kentucky and Mammoth Cave proximal to the landfill site focused on in this paper (yellow star – Figure 1). Red areas are infilled depression contours (i.e. sinkholes) showing karst geohazards generated via the interactive online map service of the Kentucky Geological Survey (accessed 2024). Note the paucity of sinkholes at Mammoth Cave due to protective siliciclastic cap rocks and in Bowling Green which is due to human alteration of the karst plain (i.e. infilling of sinkholes). Glen Lily Road Landfill, or “Old Bowling Green Landfill” is an historical case study showing challenges with siting municipal landfills near but not in the karst plain proper. Such a geographic location in context of the physiography is comparable to the Hart County Landfill or nearby Mammoth Cave however, the stratigraphic context is somewhat different but lithologically similar with all three sites shown in Figure 1 possessing a juxtaposition of carbonates and siliciclastics.

The focused study area is located in the Pennyroyal or Mississippian Plateaus physiographic region and can be subdivided from lower to higher elevation into the Karst Plain, the Dripping Springs Escarpment, and the Mammoth Cave Plateau respectively (Figure 2). Note the location of the south central Kentucky Karst Plain (also demarcated by red pattern in Figure 1) with mainly carbonate rocks that no longer can be permitted for landfills in Kentucky (legacy groundwater contamination), the upslope Dripping Springs Escarpment, comprising carbonates and mixed siliciclastic rocks and the highest elevation area known as the Mammoth Cave Plateau capped by siliciclastic rocks. Due to the grade of the escarpment, it is not possible for landfills to be sited there. The plateau area possesses minor exposed carbonates and such areas can be permitted in Kentucky for construction and demolition debris landfilled materials only.

The specific area investigated was an open land parcel that had been stripped and graded to remove logging debris bordered on three sides by wooded hill slopes and a ridge or hilltop on the west side. The site rests directly upon basal Pennsylvanian siliciclastic uplands underlain by mixed Mississippian (Chesterian) siliciclastic and carbonate rocks with adjacent karst terrain positioned at relatively low elevations. The stratigraphy of this and other landfill sites in the region typifies some of the complexity associated with the Mississippian-Pennsylvanian (Kaskaskia-Absaroka) sequence boundary or unconformity as well as the more general challenge associated with juxtaposition of mixed carbonate and siliciclastic in context of siting landfills in the south central Kentucky karst area (Figure 3). The Hart County site investigated with ER in particular presents as the Caseyville resting upon the Big Clifty Sandstone. In comparison, other locations discussed such as the Glen Lily Road Landfill at Bowling Green, and River Styx at Mammoth Cave National Park have Big Clifty directly overlying the Girkin Limestone. Note that Mammoth Cave and similar cave systems in the region are predominantly developed in limestone units directly underlying lying the Girkin Limestone in the Ste Genevieve and St. Louis limestone units although caves also develop in overlying Chester limestone units albeit are less extensive and are smaller scale. The presence of such smaller caves and conduits nonetheless pose significant karst groundwater risks in the region.

Historical siting of CCD and municipal landfills in and adjacent to the karst plain (Figure 2) is briefly discussed in order to establish context associated with decades-long challenges associated with groundwater and surface-water degradation due to landfill leachate migration. In addition to understanding the basic hydrostratigraphy, there are a number of considerations for siting landfills in this karst region including regional bedrock dip that can be determined by structure-contour mapping from subsurface databases. Bedrock dip is well known to control groundwater migration pathways in the region of Mammoth Cave (e.g. Miotke and Palmer, 1972; Palmer, 1981). Previous structural studies in the region also document generally north-northwest dipping strata with a series of northwest plunging anticlines (e.g., Russell, 1934; Moore, 1973; Marshak, et. al, 2016) in the vicinity of this and other landfills or areas near the boundary between the Karst Plain and the Dripping Springs Escarpment.

Electrical resistivity has been increasingly utilized for characterizing sites especially in and proximal to karst plains or karstic valleys or ravines adjacent to siliciclastic terrains that otherwise are generally protective of karst groundwater systems (Palmer, 1979; May et al., 2005; 2023). Our study additionally addresses decreasing the risks of landfill siting, and documenting some challenges associated with hydrostratigraphic variables encountered across sites that may affect electrical resistivity (ER) measurements and interpretation of acquired ER datasets. The presence of a protective siliciclastic cap rock parallel to bedrock strike of the southeastern edge of the Illinois Basin, is an important contributing factor in making Mammoth Cave presently the longest known mapped cave system in the world and cap rock can be detected by ER surveying. The siliciclastics are primarily sandstone with some interbedded shale units within either 1) the basal Pennsylvanian Caseyville Sandstone or 2) the uppermost Mississippian (Chesterian) Big Clifty Sandstone (Figure 3).

The site was characterized in order to document the location of the landfill relative to potential karst or related fractures or joints in rock that could possibly provide highly transmissive groundwater migration pathways from the landfill site per DWM protocol (KY Revised Statutes Chapter 224, accessed 2024). Supporting data submitted to the state of Kentucky are according to the criteria outlined in Kentucky 401 KAR 47:170, Section 3(1) and 3(2) (accessed 2024). The initial work at this CDD in Hart County resulted in the state of Kentucky recognizing that there was “a high potential for the proposed landfill to impact karst terrain” and it is well known that groundwaters are susceptible to contamination with intense karst developed in the majority of the county (Carey and Stickney, 2005). Therefore, we worked with Hart County government to specifically characterize the bedrock formations or units present, specific lithologies, and their propensity for fracture and karst formation. Furthermore, as is required, we identified all groundwater wells within ~100 meters (300 feet) of the boundary of the waste-disposal site. This background hydrogeologic investigation is considered standard protocol for landfill siting and as such is not detailed or focused on in this paper.

BACKGROUND – CHALLENGES OF LANDFILL SITING IN KARST REGIONS

The growing south-central Kentucky region particularly the area from Bowling Green to east of Mammoth Cave or the focus of this study in Hart County, has for decades been challenged with properly siting landfills for CDD, and undifferentiated industrial and municipal waste due to karst geohazards associated with numerous sinkholes (Figure 1). There have also been relatively few geophysical studies characterizing these landscapes to achieve a better understanding of modern surface geology and associated environmental and geohazards or for establishing analogs for karst reservoirs or aquifers based on site-specific geophysical datasets and various karst features such as those ranging from collapsed ponds, abandoned river reaches with solution-aided incised bedrock channels, and dome or pit caves (e.g. May and Brackman, 2014). The city of Bowling Green for example for many years engaged in siting landfills in the karst plain and the adjacent uplands straddling the Dripping Springs Escarpment and the Mammoth Cave Plateau (Figures 1 and 4). Unfortunately, these landfill sites historically proved to yield deleterious outcomes resulting in EPA/ KY Environmental Cabinet mandates of multi-year groundwater monitoring programs. Since leachate from landfills contaminated groundwater, the state also required definition of karst groundwater migration pathways and testing for water contamination. There were multiple landfills along the Barren River (Figure 4) and most infamously, on Glen Lily Road (aka the Bowling Green Old Landfill according to the U.S. Environmental Protection Agency) (Eggers, 2019). Note Hibbs Hole Cave proximal to the Glen Lily Road landfill. Such areas even atop the escarpment are proximal to high risk groundwater contamination due to abundant carbonate rocks immediately below and adjacent to the cap rock on the plateau. The table insert in the lower left in Figure 4 shows Glen Lily Road Landfill designated in the CERCLIS (Superfund Information System) database as the Bowling Green Old Landfill. Most of the municipal or solid waste facilities of which there are over 600 in Kentucky were not operated according to modern standards inclusive of lacking clay caps or project managers making much attempt to limit leachate migration (Kentucky Environmental & Energy Cabinet, 2024). Unfortunately, many of these landfills are in karst or perkiest areas and there is a need to place into context the subsurface conditions at such sites.

It was presumed by municipalities and county governing bodies back in the 1970s and 1980s that they could adequately manage waste in the karst plain but officials were eventually pressured into no longer siting landfills in the karst plain. Instead, teams of engineers that focused on construction projects and asphalt engineering with minimal understanding of siting landfills in karst, merely moved proposed sites from the bona fide karst plain to immediately adjacent perikarst areas at topographically higher locations (e.g. Glen Lily Road Landfill –Wikipedia, 2020). It was thought that siting landfills in such perikarst areas, with their apparent lack of exposed carbonate rocks, would adequately address geologic or hydrogeologic issues deemed necessary for protection of karst groundwater resources.

It is instructive to review the Glen Lily Road landfill case for example, as officials from the city engineering office in Bowling Green sited the landfill on extremely thin clastic rocks (Big Clifty Sandstone- see Figure 3) of the Mammoth Cave Plateau bordering the uppermost edge of the Dripping Springs (Chester) Escarpment that caps the carbonate rocks. In the case of the latter, these carbonate rocks, specifically the Girkin Limestone were fully exposed down the escarpment slope and into highly dissected solution or karst valleys (Figure 4). All one should have understood is that the Girkin can have well developed karst features and is even an important cave-hosting stratigraphic unit at Mammoth Cave (e.g., Palmer, 2017). Furthermore, those project managers at the time did not propose any significant boring or drilling program, and certainly did not engage in use of geophysics, or other investigative techniques such as dye tracing. The result was a costly end to the city of Bowling Green being involved first hand in the solid and municipal waste business (Eggers, 2019; Wikipedia, 2020).

Mapping of caves such as Hibbs Hole (Center for Cave & Karst Studies, 1990) near the Glen Lily Road Landfill (Figure 4) clearly showed the need for better characterization of potential landfill sites even those that traditionally may not be associated with toxic waste such as CDD landfills. Ironically, the largest mapped cave system in the world contains relatively few visible sinkholes or dolines atop the Mammoth Cave Plateau (e.g., note lack of red as noted in Figure 1 in the vicinity of Mammoth Cave). Storied cave mapping at the National Park with a length of over 685 km or 426 miles (National Park Service, 2022) and some reconnaissance geophysics, documents the risks to groundwater nonetheless on the plateau. Such geophysical work (Brackman and May, 2018; Lott et al., 2014) also links the karst groundwater manifested as phreatic cave passages to a discharge or spring area (Figures 5A to 5F). Multiple levels of cave development reflective of the complexity of karst systems in the region presents additional challenges for landfill siting in the plateau region. Such multiple levels of karst development are possible all along the entire edge of the Mammoth Cave Plateau from Bowling Green to Hart County and beyond (see Figure 1 for locations).

Similarly, the site focused on in this paper in Hart County, located in a perikarst area just east of Mammoth Cave (Figures 1, 6 and 7), could pose an elevated risk to groundwater due to its proximity to exposures of vulnerable carbonate rocks and multi-level conduit or cavern systems developed in response to changes in the Green River base level from the Pleistocene to the present (e.g. Granger et al., 2001; Granger and Fabel 2019: Palmer 2017). The presence of exposed carbonate rocks is readily evident by mere inspection of depression contours noted on both topographic and geologic maps of the area (Figures 1, 3). Another irony in regard to improper siting of landfills in the south central Kentucky karst can be related to the classic physical geology lab from Park City, Kentucky Quadrangle and which abuts the southern part of Mammoth Cave National Park in which many students are asked to identify groundwater level and depth of drilling required for development of a water well for consumption ranging from the plateau down to the base of the escarpment or near the contact with the lower lying karst plain (e.g. McKenzie et al., 2021). This depth can be calculated by introductory students by identifying the elevation of the cap rock on the Mammoth Cave Plateau and inspecting the elevation of the first occurrence downslope of depression contours and subtracting the difference in elevation. Such an exercise would have necessarily made life easier and less costly for Bowling Green and similar communities had a basic inspection of the topography on either side of the ridge for example at Glen Lily Road been conducted prior to landfill siting.

The general methodology employed in this study in Hart County, Kentucky consisted of 1) using pre-existing surface geologic mapping (Moore, 1973); 2) investigating stratigraphic relationships at the excavated nearly one-acre site including evidence for karst features; 3) conducting an electrical resistivity survey in the excavation; 4) constructing an ER model (cross sections or profiles) such as presented in karst areas as outlined by May and Brackman (2014) and 5) characterizing the site in detail to avoid karst issues by incorporating both on site stratigraphy and geophysics and 6) comparing ER models and stratigraphic conditions to known cave sites such as at Mammoth Cave.

The site was characterized by examining the proposed landfill area excavation, a drainage trench connected to the excavation, adjacent rock outcropping from the landfill and by use of electrical resistivity (ER) profiling or “soundings.” Site investigation specifically entailed documentation of stratigraphic and lithologic features within the excavation, drainage trench, and associated exposed rocks. This work included stratigraphic section measurements, ground-level photographs, and aerial or satellite images and a detailed delineation of the proposed landfill location and associated features such as berms, roadway location and ER profile lines etc. using a differential GPS unit (Figs. 6 and 7). The state of Kentucky also requires research of the hydrogeologic and geologic literature and publicly available databases and these were also taken into consideration in the development of the site conceptual model addressing hydrostratigraphic conditions (Figs. 2 and 3; Carey and Stickney, 2005). Further site characterization specific to the goals of the investigation was to establish the proximity of the proposed landfill to notable karst features, recognize regional or local control or influence on groundwater flow such as those of a stratigraphic or structural nature and to document thickness of landfill stratigraphic units.

Two electrical resistivity profiles were conducted that were oriented south-southeast to north-northeast and slightly northwest-southeast or roughly east to west and these two profiles were purposely laid out in order to be intersecting (Fig. 6). During the field work in November and December of 2020, the site had recently received heavy precipitation, resulting in saturated soils and regolith. After the location of the ER survey lines were determined, the overall distance of the survey lines was measured. The individual survey lines for ER profiling included Line C at 168 meters (550 feet) (Fig. 8A) and Line D at 134 meters (440 feet) (Fig. 8B). The desired resolution was factored in and a spacing optimal for these parameters was determined to be ~ 3.05 meters (10 feet) between electrodes. Tape measures were laid out and stainless-steel electrodes placed into the ground at the pre-determined positions. Depth of emplacement of the electrodes was determined by field conditions. Where possible, electrode stakes were driven approximately 15 cm (six inches) below ground surface to minimize contact resistance. A few ounces of a salt-water solution were then poured at the base of each electrode stake where needed, to decrease contact resistance. The electrical resistivity cables were unrolled, and an electrode bulb was placed at each stake. The bulbs were then attached to the stakes. The Advanced Geosciences, Inc. (AGI) SuperSting R8/IP and Swift switch box were in turn attached to the cables. The field data-collection system used multiple channel recording with a microcomputer and inversion processing of raw data such as outlined by Loke and others (2013) and May and Brackman (2014).

After the contact resistance test was conducted, data recording was initiated. Overall, contact resistance was noted as being relatively high due to the presence of sandy regolith or bedrock at the surface across the site. High contact resistance could result in less-than-ideal data quality, and such data challenge in extreme areas were demarcated in one of the ER cross sections and presented by a gray polygon as shown in Fig. 8B. It is important to note that the gray polygon includes data that did not influence the remaining portion of the survey. The raw ER data acquired in this polygon was not processed with the other data along the entire profile or survey line.

ER DATA ACQUISITION AND RESULTS

Evaluated ER data focuses on the two intersecting ER lines conducted specifically for investigation within the excavated pit (see Fig. 6 for location and Figs. 8A & 8B for profiles). The first line (Line C) was oriented southwest to northeast, beginning 35 meters (120 feet) south of the gravel road that led to the landfill and traversing through the proposed location of the landfill. The second line (Line D) was oriented close to west to east and was laid out to intersect Line C. As noted above, both lines were conducted using 3.048 m (10-foot) spacing for a total of 167.6 m (550 feet) in length for Line C and 134.1 m (440 feet) for Line D. A customized dipole-dipole and strong-gradient array was used (command file name ddsg56) designating that equipment used entailed 56 electrodes for both ER lines. The actual recording for Line D however was limited to fewer electrodes than 56 because that line was shorter than Line C due to field constraints. The values for the surveyed lines ranged from 10.0 to 32,278 ohm meters after normalization. Data were processed using Advanced Geoscience Inc. (AGI) 2D-EarthImager software and interfering values were removed after several iterations based on criteria of achieving low root mean squared (RMS) values yet retaining the majority of acquired data points from the surveying effort.

Study of exposures of rocks and sediment/soil observed within the excavated area document that the topographic top of the site or area near ridge tops contains weathered sandstone and pebbly sandstone or conglomerate regolith or slumped blocks of sandstone over primarily coarse-grained Caseyville sandstone that is in erosional (i.e., unconformable) contact with underlying fine-grained units. These fine-grained units are commonly organic-rich deposits, namely a thin, 0. 3 meter (less than 1 foot) discontinuous coal bed that is capping dark gray or black shale which overlies claystone or underclays replete with plant fossils (Fig. 7). These sedimentary units below the sandstone are geographically in an area mapped as being part of the basal Caseyville but are most probably Big Clifty clay-rich units as these have been excavated down to and are geographically quite near the Caseyville/Big Clifty contact (Moore, 1973; see contact between Mgb and Pca relative to northeastern corner of the “Excavated Area For Landfill” in Fig. 6).

A trench or drain trough was investigated near the northeast corner of the excavation and this afforded an excellent view of underlying fine-grained materials such as shale and claystone that appear as aquicludes and have low permeability or lack connected pore networks (see Fig. 6 for drain location and Fig. 7 for photographed stratigraphic details). Below this low permeability series of layers, the Big Clifty Sandstone may also contain additional shale units, that are also restrictive to downward infiltration of groundwater that could possibly be released from the landfill area.

The thin or “paper” coal (note elevation of this unit on ER profiles that serves as a site benchmark Figs. 8A and 8B) is extremely saturated and has some cleats but is immediately underlain by a much thicker shale unit and even thicker clay-rich rocks such as claystone or mudstone. Quartz-rich sandstone or weathered sandstone (regolith) typical of the majority of the exposed material on site is up to 25 meters (80 feet) thick and is relatively highly resistive as is shown by warm colors in the ER surveys (Figs. 8A and 8B). The sandstone contrasts markedly with underlying clay-dominated stratigraphic units that are necessarily conductive and are exhibited as cool colors in the ER surveys. Despite the fact that the site was extremely wet during the field work, the Caseyville is relatively very coarse and apparently well-drained, particularly in the uppermost topographic portions of the site. This interpretation is consistent with the stippled patterns on the geologic map designating slump clastic rock, presumably mostly sandstone and conglomerate (Moore, 1973; Fig. 3). Coal is generally resistive, but with well-developed cleats as observed at the site in the thin coal unit, it is commonly water saturated especially during wet periods. This is due to water infiltrating from the overlying sandstone or sandy/pebbly regolith, so coal actually appears as an unresolvable unit from the overlying sandstone in terms of ER signature and it is very thin (Figs. 8A and 8B; Fig. 7). It is also well established that coal beds in Kentucky and similar environs can also be considered to be aquifers or reservoirs (e.g. for coal-bed methane and CO₂ sequestration), especially where beds are fractured, and develop face and butt cleats or a cleat system (Laubach et al., 1998; Rodrigues, 2014).

Well-developed cross stratification in the Caseyville Sandstone and regional dip are either westward, or the opposite of downslope surface drainage to the east of the site. Water that infiltrates from the overlying sandstone would not necessarily only follow the regional bedrock dip (Fig. 3), but the ancient river cross-bedding structures observable on site as well (see Fig. 7 -detail bottom center photo). This trend of groundwater flow favoring the bedrock dip toward the west-northwest and internal fabric or crossbeds indicating paleocurrent during basal Pennsylvanian also westward suggests that infiltrating water will not merely flow down topographic grade to the east. Note such groundwater migration pathway would be opposite of the direction of the closest karst features (e.g. see karst features 1 and 2 in Fig. 6). Another protective stratigraphic unit for landfill siting as revealed in the trench or drain area (Fig. 7) is the presence of a relatively thick (at least one meter (three feet) exposed) clay-rich stratum immediately underlying sandstone. Such inferred hydrogeologic conditions of groundwater pathway migration opposite the karst plain are consistent with the rationale that most recharge of the south central Kentucky karst in the karst plain and adjacent escarpment generally migrates toward the regional base level flow of the Green River (cf. with River Styx in Figs. 5A through 5F)

The resulting site hydrostratigraphic model presented here in the form of annotated ER profiles (Figs. 8A and 8B), which were established to reduce landfill siting risks, necessarily combined with geologic data provide a framework for better site characterization. Maps, ER profiles and photos showing Caseyville sandstone paleocurrent data and regional dip are all to the west or northwest and an aquiclude exposed in the trench excavation are compelling pieces of evidence that this CCD landfill should pose limited to no risks to karst groundwaters (Figs. 3, 6 and 7). In the context of ER profiles obtained in the region such as at Mammoth Cave (Fig. 5A through 5F) and just east of Mammoth Cave (Green River Preserve – see Figures in May and Brackman, 2014) at Bowling Green (May et. al., 2018) in comparison, shows that the Hart County site exhibits no features indicative of karst directly underlying the site. There are however adjacent suspected karst features or more specifically dolines or sinkholes but there appears to be enough clay-rich unit thickness between the porous sandstone and karst valleys to suffice being protective of the groundwater resource (Figs. 6, 7 and 8A and 8B). This study illustrates the need to use at least some geophysics to decrease risk to groundwater in perikarst and karst areas.

The south central Kentucky region has been plagued by incorrectly sited landfills in and adjacent to fully-developed karst landscapes such as those of the Pennyroyal or Mississippi Plateau and in the subdivided Mammoth Cave Plateau, Dripping Springs Escarpment and the Karst Plain There is a need for landfill site characterization especially using geophysics such as electrical resistivity in the context of establishing a detailed site hydrostratigraphy. In “perikarst” or those areas positioned adjacent to the classic karst plain there are significant risks to groundwater due to leachate migration even at sites that may be elevated above the karst plain and that may exclusively possess exposures of siliciclastic rocks. Federal, State and local governing bodies and environmental regulators have fortunately embraced the use of electrical resistivity as a reconnaissance tool as well as an important site characterization tool in an effort to decrease risks from sited landfills in and proximal to well-developed karst terrain. This study we believe was one of the first to use ER as an aid in characterizing a CCD landfill site for the state of Kentucky and are not aware of any published results for using ER along with surface stratigraphic characterization.

Results from electrical resistivity profiling coupled with stratigraphic documentation of the CCD site in Hart County, Kentucky provide a strong conclusion that such field work decreases landfill siting risks, saving time, money and most importantly, provides more protection for karst groundwater resources. The site did however present some challenges in that extremely sandy and well drained substrates curtail the quality of the ER record, at least in the highest elevation portion of the site. This is because there were current limitations into the subsurface in such well-drained locations. This finding suggests that future ER surveying in well-drained siliciclastics may be aided by not mere use of a saline solution for decreasing contact resistance but rather, other more labor intensive measures might be taken such as the placement of pits or “pots” of conductive media such as with bentonite (Reynolds, 2011, p. 308) or aluminum foil (Advanced Geosciences Inc., 2024).

ER modeling albeit with just a few survey lines provides additional site characterization beyond boring or excavation that can be protective of groundwaters in adjacent or subjacent karst areas as illustrated by this study. Several ER profiles along with some ReMi surveys at Mammoth Cave show cave development at several levels in the plateau region that cannot be ruled out anywhere along the plateau of adjacent escarpment areas. The two ER profiles at the Hart County landfill provide insight into subsurface conditions that are better understood especially considering there is a sequence boundary or unconformity and juxtaposition of siliciclastic and carbonate rocks. It is hoped that this study may form the basis for evaluating additional landfill sites in the south central Kentucky karst and beyond with the ultimate goal of preventing improper siting of landfills in perikarst areas. Such areas are currently under increasing development pressure in particular in one of the fastest growing areas of Kentucky especially along the I-65 corridor near Bowling Green.

Author Contribution

M.M. drafted the manuscript including figures.T.B. provided field data for River Sytx area in Mammoth Cave and conducted field work there.All authors provided field and technical work at the Hart County Landfill.All authors reviewed the manuscript.

Acknowledgement

We acknowledge Northern KY University students who worked with T.B. at the Mammoth Cave River Styx location and we acknowledge the KY Geological Survey at the University of Kentucky for use of the interactive online geological map service for base maps and geologic databases.

Data Availability

Datasets and processing for ER data and seismic data presented in this manuscript can be accessed by contacting [email protected] upon request.

Advanced Geosciences Inc. (AGI), accessed 2024, help desk: https://helpdesk.agiusa.com/improve-contact-resistance#For%20Hot,%20Arid,%20Or%20Sandy%20Areas
Brackman, T. B, and May, M.T., 2018, Application of Geophysics to Engineering and Environmental Problems of the Mammoth Cave Region, Kentucky: Field Guide for 31^st Symposium on the Application of Geophysics to Engineering and Environmental Problems (SAGEEP), March 25-29, 2018, National Meeting, Nashville, Tennessee.
Eggers, C., 2019, Unused for decades, city still monitors landfill facility: Bowling Green Daily News: https://www.bgdailynews.com/news/unused-for-decades-city-still-monitors-landfill-facility/article_0313c093-16f2-541f-879b-f785b466d075.html
Carey, D.I., and Stickney, J.F., 2005, Groundwater Resources of Hart County, Kentucky: Kentucky Geological Survey County Report 50, Series XII. http://www.uky.edu/KGS/water/library/gwatlas/Hart/Hart.htm
Center for Cave & Karst Studies at Western Kentucky University, 1990, Map and Profile of Hibbs Hole Cave, Warren County, Kentucky (Drafted J.H. Smith).
Granger, D.E., Fabel, D. and Palmer, A.N., 2001, Pliocene-Pleistocene incision of the Green River, Kentucky, determined from radioactive decay of cosmogenic 26 Al and 10 Be in Mammoth Cave sediments: Geological Society of America Bulletin, v. 113, p. 825-836
Granger, D.E., and Fabel, D., 2019, Dating cave sediments with cosmogenic nuclides: Encyclopedia of Caves, Chapter 39, 3^rd Edition, p. 348-352.
Kentucky 401 KAR 47:170, Section 3(1) and 3(2) (accessed 2024), https://apps.legislature.ky.gov/law/kar/titles/401/047/170/
Kentucky Geological Survey. (Retrieved January 4, 2021). Water Well and Spring Location Map, 7.5’ Quadrangle: Munfordville.
Kentucky Energy & Environmental Cabinet (Retrieved 2024):
https://eec.ky.gov/Environmental-Protection/Waste/solid-waste/i-need-information/Pages/historic-landfill-remediation.aspx
Kentucky Geological Survey. (Retrieved 2020, December 17). Kentucky Geological Map Service - Hart County, Kentucky.
Kentucky Revised Statutes Chapter 224, accessed 2024, https://apps.legislature.ky.gov/law/statutes/chapter.aspx?id=38287
Laubach, S.E., Marrett, R.A., Olson, J.E., and Scott, A.R., 1998, Characteristics and origins of coal cleat: A review: International Journal of Coal Geology (Elsevier), v. 35, p. 175-207
Loke, M.H., Chambers, J., Rucker, D.F., Kuras, O., and Wilkinson, P.B., (2013), Recent Developments in the Direct-Current Geoelectrical Imaging Method: Journal of Applied Geophysics, v. 95, p. 135-156. DOI: 1016/j.jappgeo.2013.02.017
Lott, S., Jones, S, Shields, N., and Sosso, C., 2014, Mammoth Cave National Park: Using Electrical Resistivity and Refraction Microtremor to Identify Cave Passageways: Geological Society of America Annual Meeting, Vancouver, British Columbia, 19-22, October, 2014 (Abstract) – Paper No. 215-1
May, M.T. and Brackman, T.B., 2014, Geophysical Characterization of Karst Landscapes in Kentucky as Modern Analogs for Paleokarst Reservoirs: Interpretation, v. 2, no. 3, (August 2014), p. SF-51 to SF-63.
May, M.T., Kuehn, K.W., Groves, C.G., and Meiman, J., 2005, Karst Geomorphology and Environmental Concerns of the Mammoth Cave Region, Kentucky: Field Trip Guidebook for the 42nd National Meeting Of the American Institute of Professional Geologists, October 9, 2005, Published by AIPG KY Section in cooperation with the Kentucky Geological Survey, University of Kentucky, Lexington: publication 17336 (Guidebook Series), 49 p.
May, M.T., and Brackman, T.B., May, E.C., and Shields, N.P., 2018, Electrical Resistivity for Karst Geohazard Identification in South Central Kentucky: Geological Society of America 130^th Annual National Meeting, presentation in Karst Hazards & Monitoring (Session 126) on November 5 in Indianapolis, IN (Abstract). https://gsa.confex.com/gsa/2018AM/webprogram/Paper320640.html
May, M.T., Brackman, T.B., May, E.C., and Edwards, W.T., 2023, Using Resistivity to Reduce Landfill Siting Risks in South Central Kentucky Karst Areas: Geological Society of America Abstracts with Programs, v. 55, No. 6, doi: 10.1130/abs/2023AM-393095
Marshak, S., Larson, T.H., and Abert, C. C., 2016, Geological and geophysical maps of the Illinois Basin-Ozark Dome region: Illinois State Geological Survey, Illinois Map 23, 1:500000 https://ngmdb.usgs.gov/Prodesc/proddesc_105426.htm
McKenzie, G.D., Wilson, J.R., and Strom, R.N., Groundwater Processes, Resources, and Risks, Laboratory 13, in V.S. Cronin (Ed.) and illustrated by D. Tasa, Laboratory Manual in Physical Geology, 12 ed., 461 p. (chapter 13 p. 341-362).
Miotke, F.-D., and Palmer, A.N., 1972, Genetic Relationships Between Caves and Landforms in the Mammoth Cave National Park Area, A Preliminary Report: Hannover, Germany, 69 p.
Moore, S.L., 1973, Geologic Map of the Munfordville Quadrangle, Hart County, Kentucky: United States Geological Survey, 7.5 Minute Series, 1:24000 (digitally retrieved December 17, 2020).
National Park Service, 2022, Mammoth Cave just got a little more “Mammoth”: News Release from Mammoth Cave National Park, Kentucky https://www.nps.gov/maca/learn/news/mammoth-cave-just-got-a-little-more-mammoth.htm
Palmer, A.N., 1979, A Geological Guide to Mammoth Cave National Park: Cave Books, 196 p. (978-0914264279),
Palmer, A.N., 1981: A Geological Guide to Mammoth Cave National Park: Zephyrus Press, Teaneck, N.J., 196 p.
Palmer, A.N. (2017). Geologic History of Mammoth Cave. In: Hobbs III, H., Olson, R., Winkler, E., Culver, D. (eds) Mammoth Cave. Cave and Karst Systems of the World. Springer, Cham. https://doi.org/10.1007/978-3-319-53718-4_7 (p. 111-121)
Reynolds, J.M., 2011, An Introduction to Applied and Environmental Geophysics, 2^nd Edition: Wiley-Blackwell Publishers, 696 p.
Rodrigues, C.F., Laiginhas, C., Fernandes, M., Lemos de Sousa, M.J., and Dinis, M.A.P., 2014, The Coal cleat system: A new approach to its study: Journal of Rock Mechanics and Geotechnical Engineering, v. 6. P. 208-218.
Russell, W.L., 1934, Oil and Gas Pools of Hart County, Kentucky (Structure maps of the LeGrande pool and Logsdon valley pool, by J.H. McClurkin.): Lexington Bureau of Mineral and Topographic Survey, University of Kentucky Series VII, Bulletin no. 5, including tables, 3 plates (maps).
Wikipedia (2020 update, retrieved 2024), Glen Lily Landfill: https://en.wikipedia.org/wiki/Glen_Lily_Landfill

No competing interests reported.

Download PDF

Editorial decision: Revision requested
03 Oct, 2024
Reviews received at journal
30 Sep, 2024
Reviews received at journal
24 Sep, 2024
Reviews received at journal
12 Sep, 2024
Reviewers agreed at journal
03 Sep, 2024
Reviewers agreed at journal
29 Aug, 2024
Reviewers agreed at journal
28 Aug, 2024
Reviewers invited by journal
28 Aug, 2024
Editor assigned by journal
30 Jul, 2024
Submission checks completed at journal
30 Jul, 2024
First submitted to journal
24 Jul, 2024

You are reading this latest preprint version

Use of Electrical Resistivity Profiling to Reduce Landfill Siting Risks in the South Central Kentucky Karst

Status:

Version 1

Abstract

Figures

INTRODUCTION

METHODOLOGY

ER DATA ACQUISITION AND RESULTS

DISCUSSION OF SITE STRATIGRAPHY, STRUCTURE AND ER DATA

CONCLUSIONS

Declarations

Author Contribution

Acknowledgement

Data Availability

References

Additional Declarations

Status:

Version 1