AASHTO R13:12(2020) Standard Practice for Conducting Geotechnical Subsurface Investigations.
3.1.5. Conceptual selection of embankment types and hydraulic harrier requirements;
3.1.6. Conceptual selection of alternate foundation types and elevations of the corresponding suitable bearing strata;
3.1.7. Development of additional detailed subsurface investigations for specific structures or facilities:
3.1.8. Need for and type of subgrade or embankment foundation treatment or drainage;
3.1.9. Selection of roadway or area pavement type;
3.1.10. Need to identify areas requiring special environmental protection; and/or
3.1.11. Need to identify potential hazardous locations and types of hazardous materials.
3.2. The investigation may require the collection of sufficiently large soil and rock samples of such quality to allow adequate testing to determine the soil or rock classification or mineralogic type. or both, as well as other engineering properties pertinent to the proposed design.
3.3. This standard practice is not meant to be an inflexible description of investigation requirements. Other techniques may be applied as appropriate.
4. RECONNAISSANCE OF PROJECT AREA
4.1. Available technical data from the literature or from personal communication should be reviewed before any field program is started. This includes, but is not limited to, topographic maps, air photos, satellite imagery, geologic maps. statewide or county soil surveys and mineral resource surveys, and engineering soil maps covering the proposed project area. Reports of subsurface investigations of nearby or adjacent projects should be studied.
Note 2—While some older maps and reports may be obsolete and of limited value in light of current knowledge. a comparison of the old with the new will often reveal valuable unexpected information.
4.1.1. The United States Geological Survey and the geological surveys of the various states are the principal sources of geologic maps and reports on mineral resources and groundwater.
4.1.2. The United States Department of Agriculture. Natural Resources Conservation Service (NRCS) publishes the Web Soil Survey (WSS), available on the Internet. The site is updated and maintained online. Print copies of previously published NRCS soil surveys may also be available locally. Soil Survey Reports should enable the engineer to estimate the range in soil profile characteristics to depths of 1 .5 or 2.0 m (5 or 6 ft) for mapped soil units.
Note 3—Each soil type has a distinctive soil profile due to age, parent material, relief, climatic condition, and biological activity. Consideration of these factors can assist in identifying the various soil types. each requiring special engineering considerations and treatment. Similar engineering soil properties are often found where similar soil profile characteristics exist. Changes in soil properties in adjacent areas often indicate changes in parent material or relief. WSS information should not he used as a substitute for a field sampling and testing program.AASHTO R13 pdf download.