Particularly relevant to an earth-sheltered structure is the importance of understanding various site considerations which include topography, soil and groundwater conditions, and the lot size and location of adjacent structures.
SOIL AND GROUNDWATER
Because earth-shelter design usually requires a heavier structure and may be placed more deeply into the earth than a conventional building, consideration of soil type and groundwater conditions are particularly important to site selection. Determination of soil type is mainly important for proper structural design of footings and walls. Certain types of soils can be unsuitable due to their poor bearing capacity or their tendency to expand when wet. Groundwater conditions are important because of their impact on waterproofing as well as structural design. A high water table may require more costly structural and waterproofing techniques and make a site unsuitable.
Because of the serious consequences, the soil type and groundwater conditions of a potential site should be determined before any great effort or capital is expended on either the site or the design for the structure. A good approach is to find out initially as much as possible about local soil and groundwater conditions without actually having a physical site investigation carried out. Such general information will be more easy to obtain in densely populated areas. Sources of such information would include: local soil exploration or soil testing firms, local consulting engineers, city engineers or city offices, local realtors, owners of neighboring properties. With this preliminary information in hand, a more enlightened judgment can be made as to whether the site appears suitable (or at least that the apparent limitations are acceptable). If the results of the preliminary findings are satisfactory, a detailed site investigation should be completed before the land purchase is finalized.