ASTM D420-18 PDF Download

The ASTM D420-18 standard provides guidelines for conducting site characterizations for engineering, design, and construction purposes. The objective of the site characterization is to identify and locate significant soil and rock types and groundwater conditions within a given site area, both horizontally and vertically, and establish the characteristics of the subsurface materials through sampling or in situ testing.

The standard outlines the subjects for which an adequate site characterization will provide pertinent information for decision making. These subjects include the location of the structure within the proposed construction area, selection of construction methods and equipment, evaluation of suitable sources of construction aggregates, need for special excavating and dewatering techniques, evaluation of slope stability, conceptual selection of embankment types and hydraulic barrier requirements, conceptual selection of alternate foundation types and elevations, and development of additional detailed site characterizations for specific structures or facilities.

The site characterization may require the collection of sufficiently large soil and rock samples to allow adequate testing for soil or rock classification, mineralogic type, and engineering properties relevant to the proposed design.

The standard acknowledges that methods defined by other ASTM standards or non-ASTM techniques may be appropriate in some circumstances and provides a list to assist in the preparation of a site characterization plan.

Additionally, the standard highlights the importance of checking the site for potentially hazardous or contaminated materials, cultural/archeological conditions, and the location and nature of underground and overhead utilities before commencing the site characterization. If any unknown hazardous or contaminated materials or conditions are encountered, work should be interrupted until evaluation and revised instructions are issued.

It is important to note that this standard provides an organized collection of information and options and does not recommend a specific course of action. Professional judgment, education, and experience should be used in conjunction with this guide. The standard also emphasizes the guidelines for significant digits and rounding established in Practice D6026.