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Field Investigation Methods
Published in Mark Edward Byrnes, Field Sampling Methods for Remedial Investigations, 2023
Concrete core samples are commonly collected from building walls, floors, ceilings, and other surfaces to estimate the concentration of contaminants in the concrete if the building were to be demolished. When evaluating waste disposal options for demolished building materials, it is essential that concrete core samples be collected throughout the entire thickness of building walls, floors, ceilings, and other surfaces for laboratory analysis. This is because the results from scanning surveys (see Sections 4.1.6.1 and 4.1.6.2) and surface concrete sampling (Section 4.2.9.2.1) will overestimate the contamination levels if the building material is demolished. Core samples collected for this purpose are typically collected from the locations showing the highest contamination based on scanning surveys.
Improved Spatial Resolution in Vertical and Horizontal Holes for Measurement of Bioremediation Parameters and Histories
Published in Donald L. Wise, Debra J. Trantolo, Remediation of Hazardous Waste Contaminated Soils, 2018
The collection of a subsurface sample has been the subject of many writings. The sampling method described here allows the measurement of a wide range of components. The kind of data provided is dependent upon the sampling method and in situ conditions. A core may yield porosity, saturation, chemical concentration, biologic components and conditions, and permeability as well as mineral content, precipitated solids (e.g., metals), etc. But coring is expensive, and spatial differences may be misinterpreted as temporal differences if core is extracted at very different times. There are also large uncertainties in some parameters measured in core (e.g., permeability). In situ values are almost always preferred if available. There is also a chance that a vertical core hole can miss a vertical contaminant flow path and provide a misleading contaminant concentration.
Characterizing Hydraulic Properties
Published in Daniel B. Stephens, Andrea J. Kron, Andrea Kron, Vadose Zone Hydrology, 2018
Daniel B. Stephens, Andrea J. Kron, Andrea Kron
There are a number of advantages to characterizing sites using laboratory analyses of core samples. For instance, after the core is used to measure saturated hydraulic conductivity, other hydraulic and physical properties can be measured on the same sample, such as moisture retention curves, unsaturated hydraulic conductivity, bulk density, porosity, particle size distribution, or other geotechnical indices. Also, the same drilling methods commonly employed by geologists and geotechnical engineers to sample the soils for visual description and classification can be used to collect the cores suitable for testing hydraulic properties. Typically, multiple core samples are collected in rings stacked above each other, so that one sample can be analyzed for chemical concentrations and another for physical properties. Where the field problem is of a local nature and there is significant spatial heterogeneity in the soil, core samples usually afford the best means to quantify small-scale variability in hydraulic properties. For additional guidance refer to appropriate ASTM standards or reference materials such as Klute and Dirksen (1986).
One method of generating synthetic data to assess the upper limit of machine learning algorithms performance
Published in Cogent Engineering, 2020
Yan I. Kuchin, Ravil I. Mukhamediev, Kirill O. Yakunin
Due to inherent issues with log data classification (e.g. limited information about actual distribution of lithotypes along the borehole axes), the accurate assessment of classification’s quality for real geophysical data is not feasible. Core sampling is usually done for just a few boreholes with limited interpretation throughout the well’s depth. That is why the system of ML classification relies on expert’s assessment data. In other words, the system of ML classification is trained primarily on expert’s opinion/assessment, assuming that it is accurate. This approach, however, leads to a value paradox where actual merit of such expert’s interpretation has many inherent contradictions.