This report documents the retesting of liquefaction and non-liquefaction field case histories in the Imperial Valley with the cone penetration test (CPT). The River Park and Heber Road sites were originally tested using a mechanical cone following the 1979 Imperial Valley Earthquake (Bennett et al., 1981; Youd & Bennett, 1983). These two sites are rich in information because they have experienced several earthquakes in recent history, have been subjected to moderate levels of strong ground shaking, the liquefiable soils have appreciable fines content, and the sites contain a number of non-liquefied data points.

Recent liquefaction case histories databases (Moss et al., 2003) are based on data acquired using the electric cone, following ASTM spec. 5778. Case histories previously explored with the mechanical cone are now obsolete and the data non-standard. This report describes the acquisition and analysis of electric cone data at the Heber Road and River Park sites. These important sites can now be incorporated into liquefaction case history databases and used in back-analysis of liquefaction triggering.