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Redwood Road Landslide Repair – Castro Valley, CA

Geotechnical Investigation and Construction Observation

A section of Redwood Road in rural Alameda County failed during exceptionally heavy rainfall in the winter of 2016/2017 and subsequently closed the roadway to all through traffic. AKA was contacted by the Alameda County Public Works Agency to lead the investigation and repair design under our on-call contract with the County. AKA performed a thorough geotechnical investigation including advancing four borings up to about 40 feet deep within the landslide zone. The investigation concluded that a relatively deep landslide had damaged the Redwood Road right-of-way and may have been a re-activation of an older landslide. Following the investigation, we worked closely with our design team to develop plans and specifications suitable for contractor bidding. The repair plan included a steel beam pier and concrete retaining wall with ground-anchors (tie-backs) to provide resistance for the design lateral loads. Surface and sub-surface drainage was also addressed in the design. Construction of the repairs began in September 2017 and Redwood Road was re-opened in April 2018. AKA Engineers performed construction management during construction operations, including pier drilling, tie-back installation, and grading.


Mirador Mixed-Use Building – Oakland, CA

Geotechnical Investigation

mirador-mixed-useAKA conducted a geotechnical investigation for a new mixed-use retail/residential building at the corner of Broadway and 2nd Street in Oakland. The proposed project involves removal of the existing buildings on the property and its replacement with a 7-story building consisting of at grade construction with parking and retail space on the ground floor, residential units on the upper floors, and a rooftop terrace. The parking area will be accessed from 2nd Street and have mechanically-activated “stacked” vehicle parking pits that extend to a depth of 7 feet below the parking garage elevation. AKA’s geotechnical investigation included a detailed review of local geotechnical and historic information and utilized selective test borings to supplement the available existing data. As part of the investigation, we performed an evaluation of liquefaction potential and effects with the results of our studies indicating that the soils underlying the site have the potential to liquefy in a design-level earthquake, causing some minor settlement. Our investigation also indicated that the soils underlying the site have the potential to compress under the proposed building loads. AKA’s geotechnical investigation report provided recommendations in order to minimize the detrimental impacts of liquefaction induced settlement and densification of the site soils due to the building loads and provided recommendations for support of the building on a relatively strong and well tied together foundation.


Circle S Project – San Pablo, CA

Geotechnical Investigation

The City of San Pablo is in the process of re-developing approximately 16 acres of land located in one of the most popular areas of the city at the intersection of San Pablo Avenue and Church Lane. AKA completed two geotechnical investigations to assess subsurface conditions and provide recommendations for the development of the street network and the general suitability of the proposed project. Some of the challenges at the site include the slope stability of the Wildcat Creek bank which bounds the site along the southwest side and the existence of expansive, old and undocumented fill materials. The development of the five parcels will include new residential, retail, and medical facilities.