The Retsof salt mine in the Genesee River valley, Livingston County, New York flooded after roof collapses in 1994 created two rubble chimneys in overlying bedrock that intersected a confined aquifer in the basal glacial-drift deposits (figs. 1 and 2). Groundwater flowed downward through the rubble chimneys causing widespread drawdown in the lower confined aquifer until the mine was completely flooded in 1996 (Yager and others, 2001). By 2005, water levels in the lower confined aquifer had nearly recovered to pre-collapse conditions but the hydraulic connection through the rubble chimneys between the brine-filled mine cavity, saline-water bedrock fracture zones, and the lower confined aquifer remains. The mine contains billions of liters of saturated halite brine that is slowly being displaced upward as the weight of overlying sediments causes the mine cavity to close (Yager and others, 2009).
Saline water was detected in the lower confined aquifer in 2002 but this water was primarily from bedrock fracture zones above the mine rather than from the mine itself (Yager and others, 2012). A remedial project, which involved pumping of five bedrock wells in the collapse area, was implemented in 2006 to prevent further migration of brine and saline water into the lower confined aquifer but the project was terminated in late 2013. Water-quality samples from well Lv-322 (local no. 9422, fig. 1), which is completed in the lower confined aquifer just north of the collapse area, clearly showed a decrease in salinity during remedial pumping followed by an increase in salinity when remedial pumping stopped (fig. 3). This key well and others used to monitor saline-water migration from the collapse area were abandoned and grouted shut and are no longer available.
Information is needed to evaluate the migration of saline water from the Retsof mine-collapse area, and to determine potential future impacts of the saline water on the groundwater resource and water-supply wells in the Genesee River valley. However, drilling and installation of deep monitoring wells in the Genesee River valley is difficult and expensive and should only be undertaken with clearly defined targets and objectives to maximize their effectiveness.
Objective and Scope
The objectives of the proposed study are to non-invasively monitor saline-water migration from the Retsof mine-collapse area and to establish and sample a small water-quality network of wells to monitor the ambient groundwater quality in the confined aquifers of the Genesee River valley.
Approach
This project will collect and analyze time-domain electromagnetic, two-dimensional resistivity, and horizontal-to-vertical seismic data to help monitor saline-water migration from the Retsof mine-collapse area in the confined aquifers of the Genesee River valley. The project also will establish a groundwater-quality well network and will collect and analyze two sets of water samples from the confined aquifers.
Surface-Geophysical Surveys
Surface-geophysical surveys using electromagnetic and electrical techniques are non-invasive methods that provide subsurface measurements of electrical conductivity and resistivity useful for the evaluation of aquifer salinity. The major factors affecting the electrical conductivity and resistivity of glacial-drift deposits such as those in the Genesee River valley are porosity, clay content, and pore-water salinity. Glacial sand-and-gravel aquifers saturated with freshwater will display low conductivity/high resistivity and those saturated with saline water will display high conductivity/low resistivity. Aquifer salinity can be estimated from their electrical conductivity/resistivity based on Archie’s Law (1942). Changes in electrical conductivity/resistivity through time can be directly related to changes in pore-water salinity since the effects of porosity and clay content would remain constant.
Time-Domain Electromagnetics Time-domain electromagnetics (TDEM) is a surface-geophysical method that can be used to measure the electrical conductivity/resistivity of the subsurface. Fitterman and Hoekstra (1984) applied the TDEM sounding technique to the mapping of naturally occurring brine contamination in central Michigan. Stewart and Gay (1986) and Fitterman and Prinos (2011) used TDEM soundings to map saltwater intrusion in south Florida. For the proposed study of the Genesee River valley, the resolution and depth of investigation of the TDEM method should be sufficient to determine the electrical conductivity/resistivity of the middle and lower confined aquifers and delineate the extent of the saline-water migration, and, in addition, may provide approximate estimates of aquifer salinity.
TDEM soundings will be completed along transects across the Genesee River valley north and south of the Retsof mine-collapse area (fig. 4). The specific locations of the soundings will be limited by landowner permission and the distribution of cultural features (overhead and buried utilities) and the terrain (water bodies and swampy areas). The first TDEM soundings will be made near the Lv-322 well site (fig. 1) where the distribution of glacial drift and depth to bedrock is known and saline water is present in the lower confined aquifer. The sounding data will collected using different TDEM system configurations and settings. After collection of these soundings, inverse modeling will be used in near real time to determine the most efficient TDEM system configuration and setting for the delineation of highly saline pore waters; near real-time inverse modeling will continue as data collection proceeds and adjustments will be made to provide the best data possible. Three TDEM-sounding transects (N1, N2, and N3) each consisting of about 8 TDEM soundings will be completed north of the collapse (24 soundings total). Four transects (S1, S2, S3, and S4) each consisting of about 10 TDEM soundings will be completed south of the collapse (40 soundings total). To refine the delineation of saline-water migration, and based on the preliminary analysis of these TDEM soundings, an additional transect (dashed lines in fig. 4) consisting of about 8 TDEM soundings will be completed between either transects N1-N2 or N2-N3; and another additional transect (dashed lines in fig. 4) consisting of about 10 TDEM soundings will be completed between either transects S1-S2, S2-S3, or S3-S4 (18 soundings total).
Six months after the completion of the first set of TDEM-sounding transects, and based on their analysis, a second set of TDEM-sounding transects will be completed north and south of the collapse area where salinity changes are most likely expected to occur. The TDEM configuration and settings will be exactly the same as the first set of soundings at the same location to allow for differencing of the data sets. Therefore the differences will only reflect changes in pore water salinity. Three transects each consisting of 8 TDEM soundings will be completed north of the collapse and three transects each consisting of 10 TDEM soundings will be completed south of the collapse (54 repeated soundings total). This time-lapse TDEM data set will be differenced from the first TDEM data set collected along the three transects to evaluate changes in aquifer salinity and extent of the saline-water migration.
Horizontal-to-Vertical Seismic Horizontal-to-vertical spectral ratio (HVSR) seismic is an ambient-noise passive seismic method. This surface-geophysical method is used to estimate the depth to bedrock (Lane and others, 2008). HVSR seismic will be completed at each of the TDEM sounding locations. The depth-to-bedrock information will provide an important parameter constraint for the interpretation of the TDEM data. The analyzed passive seismic data will be compared to existing/known depth to bedrock locations at several points to create a local calibration table; data from HVSR locations without known depth to bedrock will be analyzed with that table and an estimate of error of depth to bedrock will be established.
Two-Dimensional Resistivity Two-dimensional resistivity (2D RES) is a surface-geophysical method for high-resolution imaging of the electrical conductivity/resistivity of the subsurface (Ward, 1990). Zarroca and others (2011) used 2D RES, also called earth resistivity tomography (ERT), to map saltwater intrusion in coastal aquifers in northern Spain. Barker and Moore (1998) and Hayley and others (2009) used time-lapse 2D RES to monitor changes in soils and aquifer saturation and salinity. Henderson and others (2009) used 2D RES to detect and monitor brine contamination from improperly abandoned natural gas exploration wells in a glacial-outwash aquifer. The 2D-RES depth of investigation is not sufficient to measure the electrical conductivity/resistivity of the lower confined aquifer in the Genesee River valley due to the limitations of the length of the survey line. However, 2D-RES potentially may provide higher resolution data for the middle confined aquifer than that provided by the TDEM soundings. The effectiveness and efficiency of the 2D RES method will be evaluated along two transects north of the mine collapse, one transect that has saline water in the lower confined aquifer and the other that has freshwater in the lower confined aquifer. Three 2D-RES lines, each about 1,000 feet in length, will be collected along each of the two transects (6 lines total). The 2D RES results will be compared with the TDEM sounding results.
The time-domain electromagnetic, two-dimensional resistivity, and horizontal-to-vertical seismic data sets will be analyzed as an integrated suite to maximize their synergistic character. Forward modeling methods using state-of-the software will be used to develop two-dimensional representations of the Genesee River valley north and south of collapse area that present the subsurface electrical conductivity and resistivity of the valley fill, interpreted aquifer and confining units, and estimated extent of saline-water migration in the lower confined aquifer.
Well Network
A network to monitor salinity of groundwater from existing wells (fig. 1) in the Genesee River valley will be established. The proposed monitoring network, which includes actively pumped and unused wells that were drilled for domestic, irrigation, commercial, or industrial supply, consists of three wells completed in the deep confined aquifer south of the mine-collapse area; three wells believed to be completed in the middle confined aquifer north of the collapse area; three wells in the Fowlerville Moraine; and three wells north of the Moraine (two bedrock wells and an unconsolidated well) (fig. 1).
Recent Publications
Williams, J.H., Kappel, W.M., Johnson, C.D., White, E.A., and Heisig, P.M., 2017, Time-domain electromagnetic soundings for the delineation of saline groundwater in the Genesee River valley, western New York: New York State Geological Association, Guidebook for field trips in New York, annual meeting, v. 89. (see Attached Files below: TDEM NYAGSA.pdf)
Johnson, C.D., White, E.A., Williams, J.H., and Kappel, W.M., 2017, Transient Electromagnetic Surveys Collected for Delineation of Saline Groundwater in the Genesee Valley, New York, October-November 2016: U.S. Geological Survey data release https://doi.org/10.5066/F79C6VXX
References
Archie, G.E., 1942, The electrical resistivity log as an aid in determining some reservoir characteristics, Petroleum Transactions of AIME 146, p. 54–62.
Barker, R. and Moore, J., 1998, The application of time-lapse electrical tomography in groundwater studies, The Leading Edge 17.10, p. 1454-1458.
Fitterman, D.V., and Hoekstra, P., 1984, Mapping of saltwater intrusion with transient electromagnetic soundings, in Proceeding of the NWWA/EPA Conference on Surface and Borehole Geophysical Methods in Ground Water Investigations, February 7-9, 1984, San Antonio, Texas, p. 429-454.
Fitterman, D. V. and Prinos, S. T., 2011, Results of time-domain electromagnetic soundings in Miami-Dade and southern Broward Counties, Florida, U.S. Geological Society Open-File Report 2011-1299, 42 p.
Johnson, C.D., White, E.A., Williams, J.H., and Kappel, W.M., 2017, Transient Electromagnetic Surveys Collected for Delineation of Saline Groundwater in the Genesee Valley, New York, October-November 2016: U.S. Geological Survey data release https://doi.org/10.5066/F79C6VXX
Lane, J.W., Jr., White, E.A., Steele, G.V., and Cannia, J.C., 2008, Estimation of bedrock depth using the horizontal-to-vertical (H/V) ambient-noise seismic method, in Symposium on the Application of Geophysics to Engineering and Environmental Problems, April 6-10, 2008, Philadelphia, Pennsylvania, Proceedings: Denver, Colorado, Environmental and Engineering Geophysical Society, 13 p.
Henderson, R.D., Unthank, M.D., Zettwoch, D.D., and Lane, J.W., Jr., 2009, Subsurface brine detection and monitoring in West Point, Kentucky, with 2D electrical resistivity tomography [abs.]: in Symposium on the Application of Geophysics to Engineering and Environmental Problems, March 29 - April 2, 2009, Fort Worth, Texas, Proceedings: Denver, Colorado, Environmental and Engineering Geophysical Society.
Stewart, M. and Gay, M. C. (1986), Evaluation of transient electromagnetic soundings for deep detection of conductive fluids, Ground Water, 24, p. 351–356.
Ward, S.H., 1990, Resistivity and induced polarization methods, in Ward, S. H., ed., Geotechnical and environmental geophysics no. 5: Tulsa, Okla., Society of Exploration Geophysicists, p. 147–190.
Williams, J.H., Kappel, W.M., Johnson, C.D., White, E.A., and Heisig, P.M., 2017, Time-domain electromagnetic soundings for the delineation of saline groundwater in the Genesee River valley, western New York: New York State Geological Association, Guidebook for field trips in New York, annual meeting, v. 89.
Zarroca, M., Bach, J., Linares, R., & Pellicer, X. M. , 2011, Electrical methods (VES and ERT) for identifying, mapping and monitoring different saline domains in a coastal plain region, Journal of Hydrology, 409(1), p. 407-422.
Hayley, K., Bentley, L. R., and Gharibi, M., 2009, Time-lapse electrical resistivity monitoring of salt-affected soil and groundwater. Water Resources Research 45. Online publication date: 1-Jan-2009.
Yager, R.M., Miller, T.S., and Kappel, W.M., 2001, Simulated effects of 1994 salt-mine collapse on groundwater flow and land subsidence in a glacial aquifer system, Livingston County, New York: U.S. Geological Survey Professional Paper 1611, 85 p., at http://pubs.usgs.gov/pp/pp1611/.
Yager, R.M., Misut, P.E., Langevin, C.D., and Parkhurst, D.L., 2009, Brine migration from a flooded salt mine in the Genesee Valley, Livingston County, New York: Geochemical modeling and simulation of variable-density flow: U.S. Geological Survey Professional Paper 1767, 59 p., also available online at http://pubs.usgs.gov/pp/pp1767/.
Yager, R.M., Miller, T.S., Kappel, W.M., Misut, P.E., Langevin, C.D., Parkhurst, D.L., and deVries, M.P., 2012, Simulated Flow of Groundwater and Brine from a Flooded Salt Mine in Livingston County, New York, and Effects of Remedial Pumping on an Overlying Aquifer (ver. 1.1, August 23, 2012): U.S. Geological Survey Open-File Report 2011–1286, 16 p., at http://pubs.usgs.gov/of/2011/1286.
Yager, R.M., 2013, Environmental consequences of the Retsof Salt Mine roof collapse: U.S. Geological Survey Open-File Report 2013-1174, 10 p., http://pubs.usgs.gov/of/2013/1174/.
Project
Location by County
Livingston County, NY
