State Route 125 South Toll Road- Segment 1A

Ninyo & Moore performed a geotechnical evaluation for a landslide bounded by Station 53+60 to Station 56+00 for the SR-125 South Toll Road project. The planned south abutment of the Otay River Bridge, planned to span the Otay Valley, is located in the landslide area. Nine large-diameter exploratory borings were excavated, sampled and downhole logged by an engineering geologist. Laboratory testing was performed on the collected samples and extensive slope stability analyses were performed. The remediation of the landslide included removing portions of the landslide debris and basal rupture surface in areas that are influenced by the proposed embankment for the Otay River Bridge's south abutment, without disturbing an environmental exclusion zone and noted specimens of Otay Tarplant.