Swimming Pools Supported by Dissimilar Bearing Strata

Investigation of damaged swimming pools in Southern California reveals that severe damage often occurs when the earth materials or bearing support is provided by material having different engineering properties. This often occurs in hillside area where steep slopes and alluvial filled canyons are found. Consolidation of man-made earth fill, colluvium, and alluvium is generally much greater than the parent bedrock found on many residential lots. Consolidation and creep can occur over a period of time due to changes in moisture content as fill and other earth materials become saturated. It is important that a comprehensive geotechnical investigation be carried out, even for this simplest of engineered structures. Damage to swimming pools can be mitigated by supporting the base of the pool entirely on bedrock, using deep foundations such as piers or piles.