Evidence for recent groundwater flow through Late Wisconsinan till near Toronto, Ontario

1996 ◽  
Vol 33 (4) ◽  
pp. 538-555 ◽  
Author(s):  
R E Gerber ◽  
K WF Howard
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Water ◽  
Drilling Fluid ◽  
Pore Waters ◽  
Near Surface ◽  
Degree Of Protection ◽  
Core Samples ◽  
South Central ◽  
Vertical Hydraulic Conductivity ◽  
Late Wisconsinan

The Northern till is a thick (~50 m) Late Winsconsinan diamict unit that occurs throughout south-central Ontario. The till has generally been regarded as massive and uniform, with a very low vertical hydraulic conductivity. It is similar to many other till units of mid-continental North American glaciated terrain in that it is believed to inhibit recharge to underlying aquifers and afford a high degree of protection to these aquifers from surface and near-surface sources of contamination. Standard methods of estimating hydraulic conductivity (K) for the Northern till, such as laboratory testing of core samples (other studies) and rising–falling head field piezometer tests (this study and other studies), characteristically yield values on the order of 10–11 to 10–9 m/s. Typically, these values indicate advective traveltimes through the till on the order of hundreds to thousands of years. In contrast, isotopic evidence (2H, 18O, and 3H) from till pore waters indicates the presence of modern (post-1952) waters at depths of up to 50 m, suggesting either that certain facies of the till are considerably more permeable or that minor sand lenses or hydrogeologically active secondary permeability structures are locally important. In some areas, vertical flow velocities may approach 1 m/year. By comparing pore-water isotopic data from cores acquired using mud (sodium bentonite) and dry rotary methods, this study further demonstrates that representative pore-water samples can be obtained using a drilling fluid providing care is taken in preparing core samples for analysis. Key words: till, aquitard, permeability, recharge, contaminant transport, isotopes.

Migration of acidic pore waters at the Waite Amulet tailings site near Rouyn–Noranda, Quebec, Canada

1992 ◽  
Vol 29 (3) ◽  
pp. 466-476 ◽  
Author(s):  
Ernest K. Yanful ◽  
Luc C. St-Arnaud
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Water ◽  
Mine Drainage ◽  
Geotechnical Properties ◽  
Horizontal Flow ◽  
Sulphide Mineral ◽  
Saturated Zone ◽  
Pore Waters ◽  
Dissolved Metals ◽  
Water Contents

Pore waters found in the unsaturated zone of the Waite Amulet tailings have been modified by sulphide mineral oxidation, resulting in acidic pH (near 4) and high concentrations of dissolved iron and sulphate at about 5 and 12 g/L, respectively. These pore waters have been displaced down into the shallow saturated zone of the tailings by infiltrating water. Most metals are removed from the pore water as a result of pH buffering before they reach the deeper saturated zone. However, some dissolved metals still remain in solution and are transported with the pore water through the tailings. Numerical flow modelling shows that an anisotropy in hydraulic conductivity (ratio of Kx/Ky is estimated to be 100) exists in the tailings, most likely due to the presence of horizontal fine-grained "slime" layers. The estimated horizontal pore-water velocity is almost 20 times higher than the vertical velocity. Anisotropy in hydraulic conductivity has the effect of promoting horizontal flow over vertical flow in the model. The geometry of the tailings impoundment and the assumed impermeability of the varved clay soil underlying the tailings also contribute to increased horizontal flow. To verify that a preferred horizontal flow exists and that the clay subsoil is indeed impermeable, the geotechnical properties and hydrogeochemistry of the clay are also evaluated. The results indicate that clay located beneath the tailings is slightly overconsolidated in the shallow zone but normally consolidated at greater depth by the weight of the tailings. Overconsolidation ratios reach a maximum value of 2.0. In the clay–tailings interface zone, the soil is characterized by lower in situ water contents and slightly higher undrained shear strengths Cu than the deeper clay. The water contents of the near-interface clay average about 40% and the Cu values 80 kPa, compared with an average water content of 55% and a Cu value of only 20 kPa for the clay at greater depths. These geotechnical properties confirm the presence of a desiccated oxidized upper zone identified in previous studies. It is hypothesized that fractures that could have appeared in the oxidized zone before the tailings deposition would have been closed due to consolidation by the tailings mass. Above-background sulphate concentrations observed in the clay layer at a depth of 1 m are believed to be controlled by diffusion and advection. The presence of fractures in the oxidized zone and excess pore-water pressures generated during consolidation of the clay by the tailings mass could have also influenced chemical transport. Key words : acid generation, acid mine drainage, diffusion, geotechnical, hydrogeochemistry, tailings.

scholarly journals Determining the stable isotope composition of pore water from saturated and unsaturated zone core: improvements to the direct vapor equilibration laser spectroscopy method

2015 ◽  
Vol 12 (6) ◽  
pp. 6241-6274 ◽  
Author(s):  
M. J. Hendry ◽  
E. Schmeling ◽  
L. I. Wassenaar ◽  
S. L. Barbour ◽  
D. Pratt
Keyword(s):  
High Resolution ◽  
Laser Spectroscopy ◽  
Pore Water ◽  
Water Loss ◽  
Isotope Composition ◽  
Drilling Fluid ◽  
Sample Collection ◽  
Isotopic Data ◽  
Promising Alternative ◽  
Core Samples

Abstract. A method to measure the δ2H and δ18O composition of pore waters in saturated and unsaturated geologic core samples using direct vapor equilibration and laser spectroscopy (DVE-LS) was first described in 2008, and has since been widely adopted by others. Here, we describe a number of important methodological improvements and limitations encountered in routine application of DVE-LS over several years. Generally, good comparative agreement and accuracy is obtained between core pore water isotopic data obtained using DVE-LS and that measured on water squeezed from the same core. In complex hydrogeologic settings, high-resolution DVE-LS depth profiles provide greater spatial resolution of isotopic profiles compared to long-screened or nested piezometers. When fluid is used during drilling and coring (e.g., water rotary or wet sonic drill methods), spiking the drill fluid with 2H can be conducted to identify core contamination. DVE-LS analyses yield accurate formational isotopic data for fine-textured core (e.g., clay, shale) samples, but are less effective for cores obtained from saturated permeable (e.g., sand, gravels) geologic media or on chip samples that are easily contaminated by wet rotary drilling fluid. Data obtained from DVE-LS analyses of core samples collected using wet (contamination by drill water) and dry sonic (water loss by heating) methods were also problematic. Accurate DVE-LS results can be obtained on core samples with gravimetric water contents < 5 % by increasing the sample size tested. Inexpensive Ziploc™ gas sampling bags were determined to be as good as, if not better, than other, more expensive bags. Sample storage in gas tight sample bags provides acceptable results for up to 10 days of storage; however, measureable water loss and evaporitic isotopic enrichment occurs for samples stored for up to 6 months. With appropriate care taken during sample collection and storage, the DVE-LS approach for obtaining high resolution pore water isotopic data remains a promising alternative to study the hydrogeology of saturated and unsaturated sediments. Eliminating analytical interferences from volatile organics remains a challenge.

Significance of early-diagenetic water-rock interactions in a modern marine siliciclastic/evaporite environment: Salina Ometepec, Baja California

2002 ◽  
Vol 114 (9) ◽  
pp. 1055-1069 ◽  
Author(s):  
Anna M. Martini ◽  
Lynn M. Walter ◽  
Timothy W. Lyons ◽  
Victoria C. Hover ◽  
John Hansen
Keyword(s):  
Sulfate Reduction ◽  
Pore Water ◽  
Gulf Of California ◽  
Baja California ◽  
Mineral Dissolution ◽  
Pore Waters ◽  
Near Surface ◽  
Compositional Evolution ◽  
Diagenetic Alteration ◽  
Evaporative Concentration

Abstract Although marine brines are a significant component of pore waters in sedimentary basins, there are few geochemical studies of modern analogues of such systems, especially in siliciclastic settings. For these reasons, we chose the evaporite-associated siliciclastic sediments deposited in the salt flats of the Salina Ometepec, Baja California, for an integrated investigation of sediment, pore-water, and overlying brine geochemistry. Here, the detrital components include quartz, K-feldspar, plagioclase, chlorite, biotite, and smectite, and authigenic minerals are dominated by halite, gypsum, and K-rich magnesium smectite. Thermal and saline stresses on the sediments of the Salina Ometepec keep both organic and inorganic carbon concentrations in the sediments unusually low relative to other coastal marine environments. Sediment pore waters exhibit little microbial sulfate reduction, and dissolved inorganic C contents are also very low. As a result, we did not observe carbonate and sulfide mineral authigenesis in the Salina Ometepec sediments. Instead, pore-water geochemical evolution is largely controlled by evaporative concentration of seawater, evaporite-mineral dissolution and recrystallization, and diagenetic alteration of detrital aluminosilicates. Evaporite-mineral recycling affects the compositional evolution of surficial brines even before they infiltrate the sediment. Specifically, Na+ and Cl− concentrations are increased owing to halite dissolution. We see significant Br− enrichment relative to expected seawater evaporation trends in near-surface pore water, secondary to dissolution of K- and Mg salts. Because bacterial sulfate reduction is inhibited in the Salina Ometepec sediments, sulfate concentrations are more accurate indicators of the degree of evaporation than Br−, a usually conservative element during geochemical reactions. Pore waters exhibit down-core increases in dissolved Mg2+, K+, and \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(H_{4}SiO_{4}^{0}\) \end{document} over the upper 1 m. Authigenic K-rich Mg-smectite formation is promoted by the concurrent processes of brine concentration, selective dissolution of K- and Mg-bearing salts, and dissolution of detrital aluminosilicates. Pore waters at a depth of 1 m have 87Sr/86Sr ratios that require input of Sr that is less radiogenic than that of Gulf of California seawater. This Sr is likely derived from weathering of detrital aluminosilicates from nearby volcaniclastic sources. These results show that significant chemical interactions among marine brines, evaporite minerals, and detrital aluminosilicates can occur relatively soon after sedimentation.

Monitoring well into abandoned deep-well disposal formations at Sarnia, Ontario

1990 ◽  
Vol 27 (1) ◽  
pp. 105-118 ◽  
Author(s):  
K. G. Raven ◽  
D. W. Lafleur ◽  
R. A. Sweezey
Keyword(s):  
Hydraulic Conductivity ◽  
Industrial Waste ◽  
Oil And Gas ◽  
High Pressures ◽  
Hydraulic Head ◽  
Upward Migration ◽  
Near Surface ◽  
Monitoring Well ◽  
Deep Well ◽  
Vertical Hydraulic Conductivity

A 300 m deep monitoring well was completed to the Detroit River Group of formations in Sarnia, Ontario, to evaluate the potential near-surface impacts resulting from previous deep injection of industrial waste. Detailed logging, testing, and sampling were performed to evaluate the vertical distribution of industrial waste and to determine hydraulic conductivity and hydraulic head in the disposal horizon and in the confining formations. Results of hydraulic testing indicate the hydraulic conductivity of the disposal formation is 2 × 10−9 to 2 × 10−7 m/s and that of most of the confining shale and limestone formations is less than 1 × 10−10 m/s. Analyses of groundwater samples and results from other studies show that industrial waste, characterized by elevated phenol concentrations, is present in a 10 m horizon in the Lucas dolomite disposal formation at 192 m depth. Waste is also likely present within 2–3 m thick, high-permeability limestone layers at 74 and 123 m depth in the confining units of the Hamilton Group. Because of the generally low vertical hydraulic conductivity of the confining formations, waste in the permeable limestone layers was likely introduced via poorly constructed disposal wells, cavern storage wells, or abandoned oil and gas wells. The hydraulic conductivity and hydraulic head data indicate the high pressures resulting from injection into the disposal formation have dissipated. The head within the zone of residual contamination in the disposal formation is now 8 m below the level of the St. Clair River. The hydraulic data and chemical composition of the injected waste show that the discharges of tarry liquids on the bottom of the St. Clair River in 1984 and 1985 were not caused by upward migration of injected waste. Key words: deep-well disposal, pressurized waste injection, industrial waste, Sarnia.

scholarly journals Determining the stable isotope composition of pore water from saturated and unsaturated zone core: improvements to the direct vapour equilibration laser spectrometry method

2015 ◽  
Vol 19 (11) ◽  
pp. 4427-4440 ◽  
Author(s):  
M. J. Hendry ◽  
E. Schmeling ◽  
L. I. Wassenaar ◽  
S. L. Barbour ◽  
D. Pratt
Keyword(s):  
High Resolution ◽  
Pore Water ◽  
Water Loss ◽  
Isotope Composition ◽  
Drilling Fluid ◽  
Sample Collection ◽  
Isotopic Data ◽  
Promising Alternative ◽  
Core Samples ◽  
Laser Spectrometry

Abstract. A method to measure the δ2H and δ18O composition of pore waters in saturated and unsaturated geologic core samples using direct vapour equilibration and laser spectrometry (DVE–LS) was first described in 2008, and has since been rapidly adopted. Here, we describe a number of important methodological improvements and limitations encountered in routine application of DVE–LS over several years. Generally, good comparative agreement, as well as accuracy, is obtained between core pore water isotopic data obtained using DVE–LS and that measured on water squeezed from the same core. In complex hydrogeologic settings, high-resolution DVE–LS depth profiles provide greater spatial resolution of isotopic profiles compared to long-screened or nested piezometers. When fluid is used during drilling and coring (e.g. water rotary or wet sonic drill methods), spiking the drill fluid with 2H can be conducted to identify core contamination. DVE–LS analyses yield accurate formational isotopic data for fine-textured core (e.g. clay, shale) samples, but are less effective for cores obtained from saturated permeable (e.g. sand, gravels) geologic media or on chip samples that are easily contaminated by wet rotary drilling fluid. Data obtained from DVE–LS analyses of core samples collected using wet (contamination by drill water) and dry sonic (water loss by heating) methods were also problematic. Accurate DVE–LS results can be obtained on core samples with gravimetric water contents > 5 % by increasing the sample size tested. Inexpensive Ziploc™ gas-sampling bags were determined to be as good as, if not better than, other, more expensive specialty bags. Sample storage in sample bags provides acceptable results for up to 10 days of storage; however, measurable water loss, as well as evaporitic isotopic enrichment, occurs for samples stored for up to 6 months. With appropriate care taken during sample collection and storage, the DVE–LS approach for obtaining high-resolution pore water isotopic data is a promising alternative to study the hydrogeology of saturated and unsaturated sediments. Eliminating analytical interferences from volatile organics remains a challenge.

The heterogeneity of 3-D vertical hydraulic conductivity in a streambed

2015 ◽  
Vol 47 (1) ◽  
pp. 15-26 ◽  
Author(s):  
Guangdong Wu ◽  
Longcang Shu ◽  
Chengpeng Lu ◽  
Xunhong Chen
Keyword(s):  
Hydraulic Conductivity ◽  
Three Dimensional ◽  
Deposition Process ◽  
Near Surface ◽  
River Bank ◽  
Vertical Hydraulic Conductivity ◽  
Different Populations ◽  
Permeameter Tests ◽  
D Model

The heterogeneity of vertical hydraulic conductivity (Kv) is a key attribute of streambed for researchers investigating surface water–groundwater interaction. However, few three-dimensional (3-D) Kv models with high spatial resolutions have been achieved. In this study, in-situ permeameter tests were conducted to obtain Kv values. A 3-D model with 443 Kv values was built comprising 10 lines, 10 rows, and five layers. Statistical analysis was done to reveal the spatial characteristics of Kv. The influence of bedform on Kv values was restricted to the near-surface streambed. Kv increased with the increasing distance from the south river bank for the upmost layer, but it was not the case for other layers and the combined Kv values of five layers; the spatial pattern at transects across the channel did not differ significantly. The Kv values of each layer pertained to different populations; the sediments of individual layers were formed under different sedimentation environments. The coupling of erosion/deposition process and transport of fine materials primarily contributed to a reduction of the mean and median of Kv values and an increase of heterogeneity of Kv values with depth. Thus, a collection of Kv values obtained from different layers should be considered when characterizing the heterogeneity of streambed.

Spatial Variation of Aquifer Parameters from Coastal Aquifers of Sindhudurg District, Maharashtra Using Pore-water Resistivity and Bulk Resistivity

2018 ◽  
Vol 1 (1) ◽  
pp. 28-40
Author(s):  
Suneetha Naidu ◽  
Gautam Gupta
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Water ◽  
Coastal Aquifers ◽  
Hydraulic Parameters ◽  
Formation Factor ◽  
Bulk Resistivity ◽  
Good Correspondence ◽  
Aquifer System ◽  
Transverse Resistance ◽  
Water Resistivity

Estimation of hydraulic parameters in coastal aquifers is an important task in groundwater resource assessment and development. An attempt is made to estimate these parameters using geoelectrical data in combination with pore-water resistivity of existing wells. In the present study, 29 resistivity soundings were analysed along with 29 water samples, collected from the respective dug wells and boreholes, in order to compute hydraulic parameters like formation factor, porosity, hydraulic conductivity and transmissivity from coastal region of north Sindhudurg district, Maharashtra, India. The result shows some parts of the study area reveal relatively high value of hydraulic conductivity, porosity and transmissivity. Further, a negative correlation is seen between hydraulic conductivity and bulk resistivity. The hydraulic conductivity is found to vary between 0.014 and 293 m/day, and the transmissivity varied between 0.14 and 11,722 m2/day. The transmissivity values observed here are in good correspondence with those obtained from pumping test data of Central Ground Water Board. These zones also have high aquifer thickness and therefore characterize high potential within the water-bearing formation. A linear, positive relationship between transverse resistance and transmissivity is observed, suggesting increase in transverse resistance values indicate high transmissivity of aquifers. These relations will be extremely vital in characterization of aquifer system, especially from crystalline hard rock area.

Saturated Hydraulic Conductivity of Clayey Tills and the Role of Fractures

1990 ◽  
Vol 21 (2) ◽  
pp. 119-132 ◽  
Author(s):  
Johnny Fredericia
Keyword(s):  
Hydraulic Conductivity ◽  
American Studies ◽  
Field Measurements ◽  
Present Knowledge ◽  
Saturated Hydraulic Conductivity ◽  
Field Observations ◽  
Laboratory Measurements ◽  
Vertical Hydraulic Conductivity ◽  
Data Field

The background for the present knowledge about hydraulic conductivity of clayey till in Denmark is summarized. The data show a difference of 1-2 orders of magnitude in the vertical hydraulic conductivity between values from laboratory measurements and field measurements. This difference is discussed and based on new data, field observations and comparison with North American studies, it is concluded to be primarily due to fractures in the till.

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