Ritter Park Development is an 11,000-acre master planned community. It is located in the foothills of the San Gabriel Mountains south of Palmdale, California. The project contains approximately 7,500 residential units, shopping centers, community activity centers, educational facilities, and associated infrastructure. The terrain includes steep hillsides, the San Andreas Fault, soft alluvial soil, and areas of high groundwater. The primary concerns with development of this site includes slope stability, hazards related to ground rupture and seismicity associated with the San Andreas Fault, hydroconsolidation, liquefaction, and expansive soils. Earth Systems geotechnical engineering and engineering geology studies addressed these concerns by extensive subsurface investigation by various drilling techniques (including downhole logging and video logging of borings), several miles of trenching for fault hazards, aerial photo reconnaissance, surface mapping, and geophysical exploration.