County
Naturalization of Line D (New Ohlone Creek) - Newark, CA
Geotechnical Investigation
Project Design Team Management
AKA is proud to have lead an expert team of consultants on behalf of the Alameda County Flood Control and Water Conservation District (ACFCD) for the New Ohlone Creek project in Newark, California. The Naturalization of Line D (New Ohlone Creek) transformed a conventional, man-made trapezoidal flood control channel into a natural floodplain system. The project was recognized by the American Public Works Association (APWA) with a Project of the Year Award at the 2025 APWA annual conference in Chicago.
Line D was originally constructed in 1958 as a single objective earthen channel. The channel experienced repeated bank failures, and in its quest to find a more permanent solution than patch riprap repairs, the ACFCD sought a more environmentally sustainable solution. The project reimagined the flood control channel as a New Ohlone Creek, a meandering creek traversing a broad floodplain. A new bridge crossing was incorporated into the design to allow for future maintenance and recreational use. The design leverages principles of fluvial geomorphology to create a nature equilibrium channel that can adapt to changes in climate and watershed conditions. By expanding the channel flood way and allowing the creek to meander, the project effectively contains flood flows with the channel banks.
The project took advantage of vacant land belonging to the Ohlone Community College District (OCC) immediately northwest of the channel. With the adjacent OCC campus hosting the college’s environmental program, it was recognized that there would be opportunities for students to learn more about natural systems. With coordination and assistance from AKA, the Flood Control District engaged in discussions with OCC on the naturalization concept, including its synergy with the College’s Environmental Studies program. OCC welcomed the idea and subsequently granted a permanent easement to ACFCD for implementation of the naturalization project.
Key innovative features of the project include:
- Natural Infrastructure: The project replaced the existing rock-lined trapezoidal channel with a low-flow channel and floodplain terraces.
- Ecological Benefits: The design supported a native riparian corridor, creating approximately seven acres of protected floodplain terraces, wetlands, and upland wildlife habitats.
- Community and Educational Benefits: OCC gained opportunities for environmental education and hands-on restoration experiences for students.
- Climate Adaptation: The project allows the channel and riparian corridor to adapt to changing climate conditions, providing resilience against increased flood frequencies and sea level rise.
- Partnerships: OCC granted an easement across 6.9 acres of its land for the project. ACFCD removed 3.9 cubic yards of OCC’s pesticide-contaminated soils and coordinated with the Department of Toxic Substances Control on removal and associated documents. ACFCD coordinated with Alameda County Water District to accommodate future domestic water service needs that would need to cross the easement property, including providing brackets for a future water pipeline to cross the new creek on the new bridge.
Overall, the Ohlone Creek project exemplifies a multi-benefit approach to flood control, integrating flood protection with environmental restoration, community benefits, and climate adaptation. This project addresses immediate flood risks and enhances the ecological and social value of the area, setting a new standard for sustainable flood management.
Detoxification Facility – San Leandro, CA
Alameda County Medical Center Fairmont Campus
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.
Alameda County Animal Shelter – San Leandro, CA
Fault Hazard Assessment and Geotechnical Investigation
AKA conducted a fault hazard assessment for a proposed new animal shelter as part of a comprehensive geotechnical and geologic investigation. The project site is located on county-owned property adjacent to the active Hayward fault. Our work, which was performed for the Alameda County General Services Administration, included conducting a detailed surface fault rupture hazard assessment in accordance with the Alquist-Priolo Earthquake Fault Zoning Act. The scope of our hazard assessment included excavating and logging an approximately 300-foot-long exploratory trench crossing the proposed animal shelter site. Our hazard assessment showed the site to be free of significant surface fault rupture hazards, results which we demonstrated to the satisfaction of the County’s peer reviewer in an onsite meeting. Once we had established that there were no significant geologic hazards that would preclude site development, we rapidly proceeded with supplemental borings and prepared a comprehensive design-level investigation for the project.
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.
