Download or read book Field Hydraulic Conductivity Tests for Compacted Soil Liners written by JO. Sai and published by . This book was released on 1990 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Field hydraulic conductivity tests are required to determine the in situ hydraulic conductivity of compacted clay soils used in the liners for hazardous waste management facilities. The test must be capable of measuring hydraulic conductivities of 1 × 10-9 m/s or less, and the values obtained must be representative of the overall soil liner. Few of the methods available are capable of both measuring low hydraulic conductivities and obtaining representative values. Test methods which meet these requirements include large single-ring infiltrometers, sealed double-ring infiltrometers, and collection lysimeters. The main drawback in the use of collection lysimeters is that it can take months to obtain steady-state hydraulic conductivity values. Sealed double-ring infiltrometers are practical to use and have the advantage of few ambiguities in the experimental procedures, few possibilities for yielding false low values, and are large enough to yield results representing the overall liner characteristics.

Download or read book State of the art Field Hydraulic Conductivity Testing of Compacted Soils written by Joseph O. Sai and published by . This book was released on 1991 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Field Hydraulic Conductivity Testing of a Compacted Soil Liner written by Eric Scott Steinhauser and published by . This book was released on 1987 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydraulic Conductivity and Waste Contaminant Transport in Soil written by David Edwin Daniel and published by ASTM International. This book was released on 1994 with total page 617 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Representative Specimen Size for Hydraulic Conductivity Assessment of Compacted Soil Liners written by CH. Benson and published by . This book was released on 1994 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: An alternative to field measurement of hydraulic conductivity is to conduct laboratory hydraulic conductivity tests on specimens large enough to simulate field-scale conditions. Laboratory tests can be performed rapidly using standard procedures and with accurate control of state of stress and gradient. The objective of this research program was to identify how large a specimen must be to yield field-scale hydraulic conductivity. This objective was accomplished through field testing, laboratory testing, and statistical modeling.

Download or read book In Situ Hydraulic Conductivity Tests for Compacted Soil Liners and Caps written by GP. Boutwell and published by . This book was released on 1994 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The most important geotcchnical parameter for soil liners or caps for waste facilities is hydraulic conductivity. In typical practice, the vertical conductivity normally governs the barrier effect. Regulatory agencies are increasingly requiring in situ tests in addition to laboratory- tests to verify hydraulic conductivity. Many different in situ tests have been proposed; seven have some usage. These are discussed with reference to their suitability for liner/cap evaluation. Of these, the Sealed, Double-Ring Infiltrometer and the Two-Stage Borehole test have received widest acceptance and use; each has already been used on 50 to 100 projects. Both tests are examined in detail, including theoretical basis, field procedures, and data reduction. Reasons for their preference over other methods are discussed.

Download or read book Relationship of Laboratory and Field determined Hydraulic Conductivity in Compacted Clay Layer written by A. S. Rogowski and published by . This book was released on 1990 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Infiltration Testing for Hydraulic Conductivity of Soil Liners written by JP. Stewart and published by . This book was released on 1987 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes the use of single ring infiltrometers for evaluating the hydraulic conductivity of compacted soil liners. Procedures are presented for installation and monitoring of infiltrometers in the field. Results of hydraulic conductivity estimated from infiltrometer tests on six laboratory model liners are presented and compared with the results of conventional laboratory tests. In addition, the distribution of soil saturation after prolonged infiltration testing showed that the permeant tended to follow preferred paths and did not generally advance as a uniform front as commonly assumed.

Download or read book Evaluation of Constant Head Infiltration Test Analysis Methods for Field Estimation of Saturated Hydraulic Conductivity of Compacted Clay Liners written by D. Cazaux and published by . This book was released on 2002 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Field infiltration tests are commonly used to assess the hydraulic conductivity of low permeability materials such as natural clay barriers and compacted clay liners. The soils used for compacted clay liners are always partially saturated and require very long testing times to reach steady-state flow conditions. Consequently, because they are less time consuming, laboratory tests are usually preferred for construction quality control. Nevertheless, it is well-known that field tests are more representative of the clay liner because of the scale effect. This is why, since the 1980s, the main issues associated with field procedures have been studied and several methods proposed for testing low-permeability materials within short time periods. The proposed methods are based on early-time flow analysis in unsaturated conditions and have been applied to various compacted soils under field and laboratory conditions. To evaluate these methods, we carried out a comprehensive testing program using a hydraulic field infiltrometer method (sealed single-ring infiltrometer) and a laboratory rigid-wall permeameter method that reproduces surface field test conditions. The laboratory tests were continued until saturated hydraulic conductivity was obtained so that this value could be compared against the hydraulic conductivity estimated from early-time analysis on the same specimen. The obtained results show the influence of (a) the initial moisture content, (b) the sorptivity and hydraulic head on the early-time infiltration rate, and (c) the final estimated hydraulic conductivity. A comparison of analysis methods shows the limitations of some and tries to explain the reasons for such inadequacies in the description of early-time unsaturated flows. Nevertheless, the conclusions of our study show that conventional early-time analyses give a good estimation of saturated hydraulic conductivity within a short time period compatible with construction quality-control procedures.

Download or read book State of the art Field Hydraulic Conductivity Testing of Compacted Soils written by Joseph O. Sai and published by . This book was released on 1991 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book State of the art Field Hydraulic Conductivity Testing of Compacted Soils written by Joseph O. Sai and published by . This book was released on 1991 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Field Measurement of Hydraulic Conductivity in Slowly Permeable Materials Using Early Time Infiltration Measurements in Unsaturated Media written by N. Baumgartner and published by . This book was released on 1994 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most procedures to measure the hydraulic conductivity of slowly permeable materials such as compacted soil liners are based on analyses that assume saturated, one-dimensional flow under steady-state conditions. The overwhelming problem, however, is the very long times, of the order of weeks or months in liner materials, to reach experimentally-measurable steady flow. A new field procedure is proposed for slowly permeable materials that takes advantage of the early transient flow in initially unsaturated soil. Both constant head and falling head techniques are proposed and measurement times are of the order of one half to several hours. The falling head technique has the advantage of requiring only the difference between the field-saturated and initial water contents in addition to the measured position of the falling head above the soil surface as a function of time. An experiment on the experimental soil liner at Champaign, Illinois, gave saturated hydraulic conductivity values using the constant head technique that were in good agreement with previously measured values. A laboratory test demonstrates the advantages of the falling head technique.

Download or read book Field Permeability Test for Clay Liners written by DE. Daniel and published by . This book was released on 1985 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: A method of measuring the hydraulic conductivity of compacted clay liners in the field using single-ring infiltrometers has been developed. It is assumed that the ring has a diameter that is no less than the thickness of the clay liner and that the clay liner is underlain by a freely draining material with negligible suction. Finite element analyses were performed to develop correction factors that account for horizontal seepage for cases in which the ring infiltrometer is partially embedded into the liner. The correction factors were developed for a range in diameter of the ring and for ratios of horizontal to vertical hydraulic conductivity of 1, 10, and 100. Laboratory experiments were conducted to verify the results of finite-element analyses, but the laboratory results showed considerable scatter and were successful only in demonstrating that the finite-element results show the proper trends. Finally, the test method was tried in the field on a full-sized clay liner in which the actual hydraulic conductivity of the entire liner could be calculated from the known rate of leakage. The hydraulic conductivity measured in the infiltration test agreed almost perfectly with the computed overall hydraulic conductivity of the entire liner. It is concluded that the single-ring infiltration test can be used to measure the hydraulic conductivity of clay liners, although it is difficult to measure hydraulic conductivities that are substantially lower than 1 x 10-7 cm/s. In addition, the field tests may take several weeks to complete.

Download or read book Prediction and Validation of Hydraulic Conductivity of Compacted Soil Liners written by Jody P. Kraenzel and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Variability in the Hydraulic Conductivity of a Test Pad Liner System Using Different Testing Techniques written by Matthew Jonathan Nanak and published by . This book was released on 2013 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: Historic methods (the time lag approach, the velocity approach, and the Z-t approach), utilized to reduce two stage borehole test data, were evaluated. Two of the historic methods provided viable results and were used for this research project. Additionally, these two methods are recommended for reducing two stage borehole test data in the future. Flexible wall permeameter and soil index laboratory testing were conducted on the soil used to construct three environmentally controlled compacted clay liners (test pads) to develop a zone of acceptance (placement window). Using the results from the laboratory testing, two acceptance criterions were evaluated, while one criterion was used for construction purposes and is recommended. Two stage borehole testing was conducted in Test Pads 1 and 2, while sealed double ring infiltrometer testing was conducted in Test Pad 3. After in-situ hydraulic conductivity testing was completed for Test Pads 1 and 2, Shelby tube and hand carved samples were obtained and laboratory testing was performed on the samples. Time domain reflectometry probes and tensiometers were used to monitor the movement of the wetting front during testing conducted in Test Pad 3. Hydraulic conductivity results obtained from each testing method were compared. The laboratory obtained hydraulic conductivity values from testing conducted on Shelby tube samples were compared to laboratory hydraulic conductivity values obtained from testing conducted on hand carved samples. The laboratory hydraulic conductivity values obtained from testing conducted on Shelby tube and hand carved samples were compared to field hydraulic conductivity values obtained from two stage borehole hydraulic conductivity testing. The field hydraulic conductivity values obtained from two stage borehole hydraulic conductivity testing were compared to field hydraulic conductivity values obtained from sealed double ring infiltrometer hydraulic conductivity testing. Collection of soil specimens using Shelby tubes causes the soil to compress and thereby changes the soil parameters (unit weight and hydraulic conductivity). Results of this research project indicate that comparable hydraulic conductivities within half an order of magnitude can be obtained from two stage borehole and sealed double ring infiltrometer field testing and laboratory testing conducted on hand carved and Shelby tube flexible wall samples.

Download or read book Comparison Between Various Field and Laboratory Measurements of the Hydraulic Conductivity of Three Clay Liners written by G. Didier and published by . This book was released on 2002 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: For waste facilities, field assessment of the hydraulic conductivity of fine- grained soils has been a real challenge for the past decades that has led to several types of test methods. Although standards (ASTM, NF, etc.) have been adopted in many countries, any test method needs careful application for constructing quality-control programs. The type of apparatus, its geometry, and even specimen preparation may be major sources of discrepancy. We compared hydraulic-conductivity values obtained from various field-testing methods (open, sealed, single and double infiltrometers, and borehole methods), and laboratory-testing methods such as oedometer cells or rigid and flexible-wall permeameters. Three materials were tested in this study: a compacted sandbentonite mixture, compacted clayey silt, and natural sandy clay. The field tests were run on soil-test pads whose characteristics were defined beforehand in the laboratory and the field. Comparison of the results shows a large range of hydraulic-conductivity values for a single soil sample. Such variability can commonly be explained by a scale effect, as demonstrated by the use of various types of diameter or geometry for the field or laboratory tests. Soil behavior (swelling or shrinkage) and test-analysis methods (saturated or unsaturated-flow analysis) are other important parameters. In conclusion, we identified the main problems affecting tests with infiltrometers and permeameters, and how they can be reduced or avoided by the improvement of current techniques.

Download or read book Lessons Learned from the Application of Standard Test Methods for Field and Laboratory Hydraulic Conductivity Measurement written by RJ. Dunn and published by . This book was released on 1994 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Standard ASTM test methods are now available for laboratory and field measurements of hydraulic conductivity of compacted clay soils which are used in liners and covers at waste facilities. They are widely used in waste facility design and construction quality assurance. Many of these methods require input of qualified professionals to select appropriate test parameters. Unless the parameters are carefully selected, conflict may arise over the suitability of test results and thus the regulatory acceptance of a liner or cover. Four case histories are presented which illustrate the use of both laboratory and field test methods and some of the variations which may result. These variations can usually be explained in terms of test parameters, but they emphasize the importance of suitable engineering judgement for careful selection of test conditions, and data reduction methods which are appropriate for to site conditions and allow for comparison of test results from various tests.