A soil survey contains maps and a description of each major soil in the survey area. More important, the survey describes how soil properties affect a wide range of rural and urban land uses. One of these properties, shrink/swell potential, is of great importance in the construction industry.
Shrink/swell potential is the relative change in volume to be expected with changes in moisture content, that is, the extent to which the soil shrinks as it dries out or swells when it gets wet. Extent of shrinking and swelling is influenced by the amount and kind of clay in the soil. Shrinking and swelling of soils causes much damage to building foundations, roads and other structures. A high shrink/swell potential indicates a hazard to maintenance of structures built in, on, or with material having this rating. Moderate and low ratings lessen the hazard accordingly.
Maps of shrink/swell potential have been created for two areas of the state, the Greater Phoenix and Tucson Areas of Arizona. Copies of published soil surveys can be obtained from the Natural Resources Conservation Service. Contact the NRCS Chandler Field Office at 480-988-1078 to request a copy. If you require information on digital soil data, contact Eric Wolfbrandt, Geographic Information Specialist, eric.wolfbrandt @az.usda.gov
