Portola Avenue Slide Repair

The project is located within the City right-of-way (ROW) along the north side of Portola Avenue, between I-580 and Isabel Avenue, in Livermore, CA. The project consists of work on a major arterial road in response to landslides caused by December 2022/January 2023 severe winter storms (CA23-1). The grassland pastures along the north side of Portola Avenue, between Campus Hill Drive and I-580, received a tremendous amount of rainfall with the resulting runoff flowing down the slopes. Due to poor soil conditions and excess rainfall, numerous slides occurred along the north side of Portola Avenue, spanning approximately 1,700 feet. Between the individual slope failures there was also evidence of slope movement due to soil cracks running along the top of slope, with several locations having cracks four to five inches wide. The project will: • Remove loose material and rebuild the slope with compacted engineered fill, keyed and benched into the existing slope; • Install underdrains within limits of earthwork; • Construct a concrete gutter at the top of slope and replace an earthen swale at the toe of slope; and • Replace wildlife exclusion fencing affected by the project.