Publications—Scientific Investigations Report 2007-5058
By Richard M. Yager, William M. Kappel, and L. Niel Plummer
U.S. Geological Survey Scientific Investigations Report 2007-5058
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Front Cover (569 KB) Full Report (29,325 KB) Table of analytical results for water samples Excel file (42 KB) |
Halite brine (saturation ranging from 45 to 80 percent) lies within glacial-drift deposits that fill the Onondaga Trough, a 40-km long bedrock valley deepened by Pleistocene ice near Syracuse, N.Y. The most concentrated brine occupies the northern end of the trough, more than 15 kilometers (km) beyond the northern limit of halite beds in the Silurian Salina Group, the assumed source of salt. The chemical composition of the brine and its radiocarbon age estimated from geochemical modeling with NETPATH suggest that the brine formed through dissolution of halite by glacial melt water, and later mixed with saline bedrock water about 16,500 years ago.
Transient variable-density flow simulations were conducted with SEAWAT to assess current (2005) ground-water flow conditions within the glacial drift. A transient three-dimensional (3D) model using a grid spacing of 100 meters (m) and maximum layer spacing of 30 m was used to simulate a 215-year period from 1790 to 2005. The model was calibrated to observations of water levels, chloride concentrations, and discharges of water and chloride. The model produced an acceptable match to the measured data and provided a reasonable representation of the density distribution within the brine pool. The simulated mass of chloride in storage declined steadily during the 215-year period; however, the decline was mainly due to dispersion, which is probably overestimated because of the large layer spacing. Model results suggest that saline water from waste-disposal operations associated with a chemical plant has migrated beneath the western shore of Onondaga Lake.
Two-dimensional (2D) cross-sectional models of the aquifer system within the Onondaga Trough were prepared to test the plausibility of a hypothesis that the brine was derived from a relict source of halite that was dissolved by glacial melt water. The 2D models used parameter estimates obtained with the calibrated 3D model. Model results indicated the brine could have migrated from the bedded-halite subcrop area and remained in the glacial sediments at the northern end of trough for over 16,000 years, as suggested by radiocarbon dating. The 2D models also indicated that slow dissipation of brine occurs through a mixing zone formed by upward flow of freshwater over the southern end of the brine pool. The simulated depletion rate is controlled by the rate of mixing, which is limited by the specified grid resolution and the accuracy of the numerical method used to solve the advection-dispersion equation. A numerical solution obtained by using an implicit finite-difference method with upstream weighting and a 2D grid containing a column and layer spacing of 76 m and 3 m, respectively, provided an acceptable match to chloride concentration profiles measured at three locations within the Onondaga Trough.
Abstract
Introduction
Hydrogeologic Setting
Bedrock Geology
Glacial Sediments
Hydrology
Occurrence of Brine and Saline Water and History of Brine Production
Geochemistry and Origin of Brine and Saline Water
Major and Minor Ions
Isotopic Composition
Hydrogen and Oxygen
Boron
Carbon
Origin and Age of Brine
Geochemical Modeling
Modeling Approach
Reaction Models
Alternative Hypotheses for Brine Formation
Three-Dimensional Variable-Density Flow Model
Numerical Solution
Model Design
Model Calibration
Model Fit
Simulated Aquifer Conditions
Representation of the Brine Pool
Effect of Waste Application in the Ninemile Valley
Model Sensitivity
Confining-Layer Permeability
Dispersion
Grid Resolution and Numerical Dispersion
Two-Dimensional Variable-Density Cross-Sectional Flow Model
Model Design
Simulation of Brine Origin
Conclusions
Acknowledgments
References
Appendix 1. Dissolved-gas compositions of waters in the Onondaga Trough
1–2. Maps showing—
1. Geographic features in western New York, including northern limit of Silurian salt, Valley Heads Moraine, Finger Lakes, and location of Syracuse.
2. Bedrock geology in the vicinity of the Onondaga Trough.
| 3. | Generalized section A-A’’ along Onondaga Trough showing glacial and bedrock stratigraphy. |
| 4. | Diagram showing perspective view of geologic model of Onondaga Trough showing generalized section B-B’ south of Onondaga Lake. |
5–6. Maps showing—
5. Geographic features in the Onondaga Trough showing surface drainage and springs, extent of brine pool, location of monitoring wells, and Solvay waste beds
6. Syracuse and Onondaga Lake, showing current and historic locations of natural brine springs and brine production well fields
7. Generalized section A’-A’’ showing percent saturation of brine at the northern end of the Onondaga Trough
8–12. Graphs showing—
8. Concentrations of major ions in halite brine from a representative well in the Onondaga Trough (well OD-1805), in saline bedrock water (well OD-1827), in Appalachian Basin brine and in bedded halite
9. Relation between (A) chloride and bromide and (B) calcium and magnesium in ground water in the Onondaga Trough
10. Isotopic concentrations of brine and saline waters in the Onondaga Valley: (A) deuterium and oxygen-18, (B) boron-11 and bromide to boron ratio, and (C) carbon-13 and carbon-14
11. Relation between chloride and density in halite brine samples
12. Residual plots showing relations between observed and simulated values, and weighted residuals: (A) all observations, (B) water levels, (C) chloride concentrations, and (D) ground-water discharge and chloride mass flows
| 13. | Map showing water levels and chloride concentrations simulated for current conditions in the lower aquifer. |
| 14. | Generalized section A-A’’ showing observed and simulated hydraulic head along the Onondaga Trough. |
| 15. | Graphs showing depth profiles of observed and simulated chloride concentrations at: (A) OD-1830, beneath Onondaga Lake, (B) OD-1805, 1 kilometer south of lake, (C) OD-1804, 5 kilometers south of lake, (D) chloride concentration history at OD-1805. |
| 16. | Maps showing simulated chloride concentration and ground-water velocity near the southern end of the brine pool under current conditions (2005) in: (A) confining layer and (B) lower aquifer |
| 17. | Graph showing mass flows of chloride discharged from aquifer system during 215-year simulation. |
| 18. | Isosurfaces of equal chloride concentration during 215-year simulation in (A) 1820, prior to brine pumping, (B) 1920, after brine pumping, and (C) 2005, current conditions. |
| 19. | Maps showing simulated chloride concentration and ground-water velocity in the Ninemile Valley in (A) 1920, cessation of brine pumping, (B) 1946, closure of waste bed A, (C) 1985, closure of waste beds B and C, and (D) 2005, current conditions. |
| 20. | Perspective views showing simulated extent of saline water migration from Solvay waste beds in 2005 under three conditions based on percent of waste chloride application (A) model 3D-A, 15 percent, (B) model 3D-B, 25 percent, and (C) model 3D-C, 100 percent. |
21–22. Graphs showing—
21. Depth profiles showing sensitivity of simulated chloride concentrations to model grid spacing (model E) and TVD method (model F): (A) well OD-1830, beneath Onondaga Lake; (B) well OD-1805, 1 kilometer south of lake; and (C) well OD-1804, 5 kilometers south of lake
22. Simulated chloride mass in storage: (A) during 215-year simulation, and (B) during 1000-year simulation
| 23. | Schematic diagrams showing (A) design of two-dimensional variable-density flow model, and (B) chloride concentrations at the end of 17,000-year simulation with model 2D-C. |
| 24. | Graphs showing chloride mass and concentration profiles simulated with 2D models: (A) percent of initial mass remaining in aquifer system; (B) well OD-1830, beneath Onondaga Lake; (C) well OD-1805, 1 kilometer south of lake; and (D) well OD-1804, 5 kilometers south of lake. |
Yager, R.M., Kappel, W.M., and Plummer, L.N., 2007, Halite brine in the Onondaga Trough near Syracuse, New York: characterization and simulation of variable-density flow: U.S. Geological Survey Scientific Investigations Report 2007–5058, 40 p.
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