State-of-the-art Field Hydraulic Conductivity Testing of Compacted Soils PDF Download

Author: JO. Sai
Publisher:
ISBN:
Category : Collection lysimeter
Languages : en
Pages : 11

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Book Description
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.

Author: Joseph O. Sai
Publisher:
ISBN:
Category : Soil permeability
Languages : en
Pages : 8

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Author: Eric Scott Steinhauser
Publisher:
ISBN:
Category : Engineered barrier systems (Waste disposal)
Languages : en
Pages : 200

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Author: David Edwin Daniel
Publisher: ASTM International
ISBN: 0803114427
Category : Bentonite
Languages : en
Pages : 617

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Author: CH. Benson
Publisher:
ISBN:
Category : Block samples
Languages : en
Pages : 27

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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.

Author: GP. Boutwell
Publisher:
ISBN:
Category : Borehole test
Languages : en
Pages : 40

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Book Description
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.

Author: A. S. Rogowski
Publisher:
ISBN:
Category : Clay
Languages : en
Pages : 240

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Author: JP. Stewart
Publisher:
ISBN:
Category : Compacted soils
Languages : en
Pages : 10

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Book Description
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.

Author: D. Cazaux
Publisher:
ISBN:
Category : Clay liner
Languages : en
Pages : 25

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Book Description
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.

Author: Joseph O. Sai
Publisher:
ISBN:
Category : Soil permeability
Languages : en
Pages : 5

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