County

Geotechnical and Fault Hazard Investigations
Geotechnical Services during Construction

AKA conducted a fault hazard assessment for a proposed new detoxification facility at the Alameda County Medical Center complex in San Leandro. Our assessment, which was performed for the Alameda County General Services Administration, initially focused on an available parcel of land between two active traces of the Hayward fault. Exploratory trenching performed by AKA rapidly established this to be an unfavorable site. However, utilizing available data we were able to identify a nearby alternate site that our subsequent trenching showed to be free of significant surface fault rupture hazards. Once we had demonstrated the absence of a significant fault hazard, we rapidly proceeded with supplemental borings and prepared a comprehensive design-level investigation for the project. Follow-on services provided by AKA included a geotechnical review of the project plans and specifications and comprehensive geotechnical services during construction. The detoxification facility is now open on the alternate site that we helped to identify, which proved also to be preferred by the County from a usage perspective.

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.