IMPACTS OF SOIL COLLAPSE ON THE URBAN LANDSCAPE

Soil collapse, mainly hydroconsolidation, is causing increased structural damage in rapidly urbanizing areas, particularly in the western United States. Collapse is mainly engendered by anthropically accelerated groundwater (perched and regional) rise and decline, particularly owing to large-scale importation of urban irrigation water for residential (tract houses) and recreational (mainly golf courses) use. Urban soil collapse is expressed geomorphically by sink holes, ground fissures, subsidence and differential settlement. Particularly evident in Los Angeles and Riverside counties, California, soil collapse directly impacts thousands of new houses and infrastructure, resulting in litigation and damage allegations of tens to hundreds of millions of dollars. Indirect impacts include formation of urban “subsidence zones,” dramatic improvement in engineering and geologic standards-of-practice, soil-collapse disclosure in real-estate transactions, and litigation challenges for the geotechnical practitioner, mainly as a defendant or as an expert witness for plaintiffs.