WorldWide Drilling Resource

WorldWide Drilling Resource ® is a proud member of this association. National Drilling Association Tel: 877-632-4748 Fax: 216-803-9900 www.nda4u.com 11 WorldWide Drilling Resource ® DECEMBER 2013 Soil Sampling Primer by Scott Cosby Soil sampling is an important part of a geotechnical investigation; see WWDR November 2011 article. Our office obtains these samples in two ways: (1) Hand auger and/or by shovel. (2) Drill rig assisted, push tube sam- pling, etc. This month’s article will focus on soil sampling by examining a basic definition, soil survey process, and sample types. In this article, I’m not endorsing one sam- pler and/or method over another, this is all based on my experiences and meant to give a basic understanding of soil sam- pling. A soil sample is representative from where it is taken. A good representative soil sample is important to obtain the physical properties of soil and later test- ed in the laboratory for the initial site design or repair of distress to earthworks and structures caused by subsurface conditions. Soil is comprised of minerals, soil organic matter (SOM), water, and air. The composition and proportion of these components greatly influence soil physical properties, including texture, structure, and porosity. In turn, these properties affect air and water move- ment in the soil, and thus the soil’s abil- ity to function. The whole process of soil sampling begins with a careful soil survey to map out locations for specific soils to be ob- tained. This is done with county-based soil survey books or the Web Soil Survey , both maintained by the U.S. Department of Agriculture - Natural Resources Conservation Service. The soil survey books also contain other useful infor- mation such as the general soils map; use and management of soils, process- es, and factors of soil formation; and landforms and surface geology. The initial soil survey process in- cludes: 1. Locating the area of interest in the map sheets. 2. Note the map unit symbol (ex- ample: ScC, KnC, or LaC). 3. Go to the text or tables for infor- mation on that map unit. Soil samples are often categorized as being either disturbed or undisturbed. A disturbed sample is one in which the structure of the soil has been changed (e.g., tilled or earthmoving activities), and only properties of the soil grains (e.g., grain size distribution, Atterberg limits, and possibly the water content) can be accurately determined. An un- disturbed sample is one where the con- dition of the soil in the sample is close enough to the natural conditions of the soil. There are numerous online sources available on this topic. Soil survey infor- mation by state can additionally be found at the following Web site: http://soils. usda.gov/survey/printed_surveys/ Scott Scott Cosby may be contacted via e-mail at admin@ worldwidedrillingresource.com Soil sampling and obtained sample. &% ! "" * "(%$ ))) (" $( ' & $ %# # " (" $( $ ( " !" !! ! &% ! % ! (" $( & $ $ $ " ! $ $ ! ! $ ! $ # $ $ $