Hydraulic conductivity and diffusion monitoring of the Keele Valley Landfill liner, Maple, Ontario

1993 ◽  
Vol 30 (1) ◽  
pp. 124-134 ◽  
Author(s):  
K. S. King ◽  
R. M. Quigley ◽  
F. Fernandez ◽  
D. W. Reades ◽  
A. Bacopoulos
Keyword(s):  
Hydraulic Conductivity ◽  
Major Ions ◽  
Geometric Mean ◽  
Actual Performance ◽  
Landfill Liner ◽  
Monitoring Programs ◽  
Field Diffusion ◽  
Clayey Silt ◽  
Sand And Gravel

The 99-ha Keele Valley Landfill is located in a former sand and gravel pit at Maple, Ontario. The base and sides of the pit are lined with a minimum of 1.2 m of excavated clayey silt till recompacted to achieve a design hydraulic conductivity of 1 × 10−8 cm/s or less. Extensive construction controls and monitoring programs have been implemented to determine the hydraulic conductivity and advective performance of the liner. A total of 267 postcompaction laboratory hydraulic conductivity (k) tests indicated that the first two stages of the liner had a geometric mean k of 7.7 × 10−9 cm/s. Calculations of in situ hydraulic conductivity based on lysimeter effluent collection rates show decreases in k to field values close to the laboratory values. In situ electrical conductivity sensors and lysimeter effluent chemistry measurements have monitored the advance of leachate-derived chemicals into the liner. Concurrent field verification by liner exhumation and chemical analysis has confirmed the importance of diffusion as the dominant migration mechanism through this low-k liner. Similar concentration trends for major ions have been observed in the field lysimeter effluents, effluents from laboratory liner–leachate compatibility tests, and pore water extracted from core samples of sections of exhumed liner exposed to leachate. The multicomponent field and laboratory testing and monitoring programs have shown good cross-agreement, and the actual performance of the liner has been close to preconstruction predictions. Key words : landfill, clayey liner, field hydraulic conductivity, field diffusion, municipal solid waste leachate, field lysimeter test, laboratory hydraulic conductivity, liner–leachate compatibility.

scholarly journals Accelerated gravity testing of aquitard core permeability and implications at formation and regional scale

2015 ◽  
Vol 12 (3) ◽  
pp. 2799-2841
Author(s):  
W. A. Timms ◽  
R. Crane ◽  
D. J. Anderson ◽  
S. Bouzalakos ◽  
M. Whelan ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Preferential Flow ◽  
Fluid Velocity ◽  
Regional Scale ◽  
Geotechnical Centrifuge ◽  
Regional Flow ◽  
Clayey Silt ◽  
Vertical Hydraulic Conductivity ◽  
Core Permeability

Abstract. Evaluating the possibility of leakage through low permeability geological strata is critically important for sustainable water supplies, the extraction of fuels from strata such as coal beds, and the confinement of waste within the earth. The current work demonstrates that relatively rapid and reliable hydraulic conductivity (K) measurement of aquitard cores using accelerated gravity can inform and constrain larger scale assessments of hydraulic connectivity. Steady state fluid velocity through a low K porous sample is linearly related to accelerated gravity (g-level) in a centrifuge permeameter (CP) unless consolidation or geochemical reactions occur. The CP module was custom designed to fit a standard 2 m diameter geotechnical centrifuge (550 g maximum) with a capacity for sample dimensions of 30 to 100 mm diameter and 30 to 200 mm in length, and a maximum total stress of ~2 MPa at the base of the core. Formation fluids were used as influent to limit any shrink–swell phenomena which may alter the permeability. Vertical hydraulic conductivity (Kv) results from CP testing of cores from three sites within the same regional clayey silt formation varied (10−7 to 10−9 m s−1, n = 14). Results at one of these sites (1.1 × 10−10 to 3.5 × 10−9 m s−1, n = 5) that were obtained in < 24 h were similar to in situ Kv values (3 × 10−9 m s−1) from pore pressure responses over several weeks within a 30 m clayey sequence. Core scale and in situ Kv results were compared with vertical connectivity within a regional flow model, and considered in the context of heterogeneity and preferential flow paths at site and formation scale. More reliable assessments of leakage and solute transport though aquitards over multi-decadal timescales can be achieved by accelerated core testing together with advanced geostatistical and numerical methods.

Statistical analyses of compacted clay landfill liners. Part 1: model development

1994 ◽  
Vol 21 (5) ◽  
pp. 872-882 ◽  
Author(s):  
Scott B. Donald ◽  
Edward A. McBean
Keyword(s):  
Hydraulic Conductivity ◽  
Geometric Mean ◽  
Model Development ◽  
Statistical Analyses ◽  
Compacted Clay ◽  
Clay Liners ◽  
Landfill Liner ◽  
Landfill Liners ◽  
Clay Liner ◽  
Spatial Correlation Structure

The acceptance of compacted clay liners, from a management point of view, has been a source of major concern because of the uncertainty associated with the hydrogeologic properties of the clay. By examining the flux of leachate through the compacted clay liner of a typical engineered landfill, where the hydraulic conductivity of the clay is represented by a stochastic process, an acceptance protocol suitable for compacted clay landfill liners is derived. Determination of the equivalent hydraulic conductivity of the clay liner is accomplished by comparing the flux of leachate through a homogeneous representation of the clay with the flux obtained by Monte Carlo analyses. Acceptance criteria are subsequently developed based on a statistical technique which calculates the confidence limits about a percentile of a probability distribution as well as about the mean of the distribution. For the landfill configuration simulated, the results indicate that the hydraulic conductivity of a compacted clay landfill liner follows a lognormal distribution and exhibits virtually no spatial correlation structure. In addition, for liners exhibiting a geometric mean conductivity of 10−7 cm/s and a standard deviation of 0.3, the geometric mean value is a conservative estimate of the hydraulic conductivity of the clay, provided the liner is constructed in a series of four 150 mm lifts. Key words: clay liners, hydraulic conductivity, statistical analyses, latin hypercube, equivalent hydraulic conductivity.

An assessment of the single-head analysis for the constant head well permeameter

1992 ◽  
Vol 72 (4) ◽  
pp. 489-501 ◽  
Author(s):  
W. D. Reynolds ◽  
G. C. Topp ◽  
S. R. Vieira
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Texture ◽  
Soil Structure ◽  
Geometric Mean ◽  
Field Method ◽  
Silty Clay ◽  
Constant Head ◽  
The Many

An in-situ constant head well permeameter (CHWP) method employing three or more ponded heads per well was used to establish relationships between field-saturated hydraulic conductivity (Kfs), matric flux potential [Formula: see text], the alpha parameter (α*), soil texture, and soil structure. The relationships were then used to evaluate a single-head CHWP technique which employs representative mean α* values in the determination of Kfs and [Formula: see text]. The measurements were made at several depths on four soils which ranged in texture from loamy sand to silty clay, and in structure from single grain to strong, fine subangular blocky. The Kfs and [Formula: see text] results obtained from the multiple-head CHWP measurements were found to be highly variable within and between soils, yielding within-soil ranges as high as 3.5 orders of magnitude and standard deviation factors (SDF) as high as 5.1. The geometric mean (GM) Kfs and [Formula: see text] values were also highly variable between soils, but they were controlled primarily by soil structure rather than by soil texture or other factors. The α* values, on the other hand, were relatively consistent both within and between soils, yielding an overall SDF of only 1.2 and an overall GM of 11 m−1. Use of α* = 11 m−1 in the single-head CHWP technique yielded Kfs and [Formula: see text] values which were usually accurate to within a factor of 2, and often accurate to within ±25%. These levels of accuracy are within acceptable limits for a field method, considering the many potential sources of error and the extreme range and variability of Kfs and [Formula: see text] normally encountered in the field. Key words: Constant head well permeameter, hydraulic conductivity, matric flux potential, alpha parameter, soil texture, soil structure, single-head analysis

scholarly journals Vertical hydraulic conductivity of a clayey-silt aquitard: accelerated fluid flow in a centrifuge permeameter compared with in situ conditions

2014 ◽  
Vol 11 (3) ◽  
pp. 3155-3212 ◽  
Author(s):  
W. A. Timms ◽  
R. Crane ◽  
D. J. Anderson ◽  
S. Bouzalakos ◽  
M. Whelan ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Centrifugal Force ◽  
Stress Conditions ◽  
K Value ◽  
Geotechnical Centrifuge ◽  
In Situ Conditions ◽  
Clayey Silt ◽  
Vertical Hydraulic Conductivity ◽  
Permeameter Tests

Abstract. Evaluating the possibility of leakage through low permeability geological strata is critically important for sustainable water supplies, extraction of fuels from strata such as coal beds, and confinement of waste within the earth. Characterizing low or negligible flow rates and transport of solutes can require impractically long periods of field or laboratory testing, but is necessary for evaluations over regional areas and over multi-decadal timescales. The current work reports a custom designed centrifuge permeameter (CP) system, which can provide relatively rapid and reliable hydraulic conductivity (K) measurement compared to column permeameter tests at standard gravity (1g). Linear fluid velocity through a low K porous sample is linearly related to g-level during a CP flight unless consolidation or geochemical reactions occur. The CP module is designed to fit within a standard 2 m diameter, geotechnical centrifuge with a capacity for sample dimensions of 30 to 100 mm diameter and 30 to 200 mm in length. At maximum RPM the resultant centrifugal force is equivalent to 550g at base of sample or a total stress of ~2 MPa. K is calculated by measuring influent and effluent volumes. A custom designed mounting system allows minimal disturbance of drill core samples and a centrifugal force that represents realistic in situ stress conditions is applied. Formation fluids were used as influent to limit any shrink-swell phenomena which may alter the resultant K value. Vertical hydraulic conductivity (Kv) results from CP testing of core from the sites in the same clayey silt formation varied (10−7 to 10−9 m s−1, n = 14) but higher than 1g column permeameter tests of adjacent core using deionized water (10−9 to 10−11 m s−1, n = 7). Results at one site were similar to in situ Kv values (3 × 10−9 m s−1) from pore pressure responses within a 30 m clayey sequence in a homogenous area of the formation. Kv sensitivity to sample heterogeneity was observed, and anomalous flow via preferential pathways could be readily identified. Results demonstrate the utility of centrifuge testing for measuring minimum K values that can contribute to assessments of geological formations at large scale. The importance of using realistic stress conditions and influent geochemistry during hydraulic testing is also demonstrated.

scholarly journals Laboratory and In Situ Determination of Hydraulic Conductivity and Their Validity in Transient Seepage Analysis

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1131
Author(s):  
Soonkie Nam ◽  
Marte Gutierrez ◽  
Panayiotis Diplas ◽  
John Petrie
Keyword(s):  
Hydraulic Conductivity ◽  
Field Measurements ◽  
Natural Soil ◽  
In Situ Tests ◽  
Seepage Analysis ◽  
Soil Deposits ◽  
Seepage Modeling ◽  
Sample Disturbance

This paper critically compares the use of laboratory tests against in situ tests combined with numerical seepage modeling to determine the hydraulic conductivity of natural soil deposits. Laboratory determination of hydraulic conductivity used the constant head permeability and oedometer tests on undisturbed Shelby tube and block soil samples. The auger hole method and Guelph permeameter tests were performed in the field. Groundwater table elevations in natural soil deposits with different hydraulic conductivity values were predicted using finite element seepage modeling and compared with field measurements to assess the various test results. Hydraulic conductivity values obtained by the auger hole method provide predictions that best match the groundwater table’s observed location at the field site. This observation indicates that hydraulic conductivity determined by the in situ test represents the actual conditions in the field better than that determined in a laboratory setting. The differences between the laboratory and in situ hydraulic conductivity values can be attributed to factors such as sample disturbance, soil anisotropy, fissures and cracks, and soil structure in addition to the conceptual and procedural differences in testing methods and effects of sample size.

Predicting the saturated hydraulic conductivity of sand and gravel using effective diameter and void ratio

2004 ◽  
Vol 41 (5) ◽  
pp. 787-795 ◽  
Author(s):  
Robert P Chapuis
Keyword(s):  
Hydraulic Conductivity ◽  
Void Ratio ◽  
Saturated Hydraulic Conductivity ◽  
Effective Diameter ◽  
Predictive Capacity ◽  
K Value ◽  
Maximum Value ◽  
New Equation ◽  
Silty Soils ◽  
Sand And Gravel

This paper assesses methods to predict the saturated hydraulic conductivity, k, of clean sand and gravel. Currently, in engineering, the most widely used predictive methods are those of Hazen and the Naval Facilities Engineering Command (NAVFAC). This paper shows how the Hazen equation, which is valid only for loose packing when the porosity, n, is close to its maximum value, can be extended to any value of n the soil can take when its maximum value of n is known. The resulting extended Hazen equation is compared with the single equation that summarizes the NAVFAC chart. The predictive capacity of the two equations is assessed using published laboratory data for homogenized sand and gravel specimens, with an effective diameter d10 between 0.13 and 1.98 mm and a void ratio e between 0.4 and 1.5. A new equation is proposed, based on a best fit equation in a graph of the logarithm of measured k versus the logarithm of d102e3/(1 + e). The distribution curves of the differences “log(measured k) – log(predicted k)” have mean values of –0.07, –0.21, and 0.00 for the extended Hazen, NAVFAC, and new equations, respectively, with standard deviations of 0.23, 0.36, and 0.10, respectively. Using the values of d10 and e, the new equation predicts a k value usually between 0.5 and 2.0 times the measured k value for the considered data. It is shown that the predictive capacity of this new equation may be extended to natural nonplastic silty soils, but not to crushed soils or plastic silty soils. The paper discusses several factors affecting the inaccuracy of predictions and laboratory test results.Key words: permeability, sand, prediction, porosity, gradation curve.

Effect of temperature on streambed vertical hydraulic conductivity

2013 ◽  
Vol 45 (1) ◽  
pp. 89-98 ◽  
Author(s):  
Weihong Dong ◽  
Gengxin Ou ◽  
Xunhong Chen ◽  
Zhaowei Wang
Keyword(s):  
Hydraulic Conductivity ◽  
Water Temperature ◽  
Sediment Cores ◽  
Effect Of Temperature ◽  
In Situ Tests ◽  
Effect Of Water ◽  
Vertical Hydraulic Conductivity ◽  
Increasing Trend ◽  
Streambed Vertical Hydraulic Conductivity

In this study, in situ and on-site permeameter tests were conducted in Clear Creek, Nebraska, USA to evaluate the effect of water temperature on streambed vertical hydraulic conductivity Kv. Fifty-two sediment cores were tested. Five of them were transferred to the laboratory for a series of experiments to evaluate the effect of water temperature on Kv. Compared with in situ tests, 42 out of the 52 tests have higher Kv values for on-site tests. The distribution of water temperature at the approximately 50 cm depth of streambed along the sand bar was investigated in the field. These temperatures had values in the range 14–19 °C with an average of 16 °C and had an increasing trend along the stream flow. On average, Kv values of the streambed sediments in the laboratory tests increase by 1.8% per 1 °C increase in water temperature. The coarser sandy sediments show a greater increase extent of the Kv value per 1 °C increase in water temperature. However, there is no distinct increasing trend of Kv value for sediment containing silt and clay layers.

Decrease in Hydraulic Conductivity of a Paddy Field using Biocalcification in situ

2016 ◽  
Vol 33 (8) ◽  
pp. 690-698 ◽  
Author(s):  
Kağan Eryürük ◽  
Daisuke Suzuki ◽  
Shin'ya Mizuno ◽  
Tetsuji Akatsuka ◽  
Takayuki Tsuchiya ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Paddy Field

Estimation and Scaling of the Near-Saturated Hydraulic Conductivity

1999 ◽  
Vol 30 (3) ◽  
pp. 177-190 ◽  
Author(s):  
Per Atle Olsen
Keyword(s):  
Hydraulic Conductivity ◽  
Saturated Hydraulic Conductivity ◽  
Scaling Analysis ◽  
Laboratory Measurements ◽  
Estimation Errors ◽  
Geometric Means ◽  
Top Soil ◽  
Structured Soils ◽  
Order Of Magnitude

The hydraulic conductivity in structured soils is known to increase drastically when approaching saturation. Tension infiltration allows in situ infiltration of water at predetermined matric potentials, thus allowing exploration of the hydraulic properties near saturation. In this study, the near saturated (ψ≥-0.15 m) hydraulic conductivity was estimated both in the top- and sub-soil of three Norwegian soils. A priory analysis of estimation errors due to measurement uncertainties was conducted. In order to facilitate the comparison between soils and depths, scaling analysis was applied. It was found that the increase in hydraulic conductivity with increasing matric potentials (increasing water content) was steeper in the sub-soil than in the top-soil. The estimated field saturated hydraulic conductivity was compared with laboratory measurements of the saturated hydraulic conductivity. The geometric means of the laboratory measurements was in the same order of magnitude as the field estimates. The variability of the field estimates of the hydraulic conductivity from one of the soils was also assessed. The variability of the field estimates was generally smaller than the laboratory measurements of the saturated hydraulic conductivity.

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