Remediation is a critical component for brownfield redevelopment and this project at 3093 Broadway in Oakland, California is no exception. A former car dealership operated at this 3.4-acre site, which is located along the historical Auto Row. During the dealership’s operations, underground storage tanks released petroleum hydrocarbons into the groundwater.
Langan was tasked with mitigating the petroleum hydrocarbons and associated compounds in soil and groundwater. The challenge was to implement a remediation system before construction without endangering the project’s construction schedule or financial viability.
To meet these constraints, Langan designed and implemented a sulfate delivery system within the building foundation. This system introduced a continuous supply of sulfate into the groundwater. The sulfate stimulated native microorganisms to degrade the petroleum hydrocarbons.
Our team drilled 42 remediation borings within the areas of greatest groundwater impacts and backfilled with a mixture of gypsum (calcium sulfate) and other materials. We placed the gypsum below the groundwater table to slowly dissolve and provide an ongoing source of sulfate to the groundwater.
We completed the installation of the bioremediation system prior to construction’s start date. In fact, the process was well underway before the site became inaccessible during site’s earthwork and building construction. We also re-installed monitoring wells at the new ground level for post-remediation monitoring. The approach placed the necessary remediation reagent prior to building construction to avoid the difficulty of placement during or after building construction.
Langan’s environmental and geotechnical teams coordinated closely during remediation design to address potential geotechnical implications. We carefully located remediation borings within the building footprint where they would not compromise the building’s foundation. We also carefully coordinated the gypsum backfill mixture to achieve both the environmental and geotechnical requirements for the project — demonstrating the value of our team’s integrated services for land development.
Langan is proud to work with the developer, CityView, on this well-planned and thoughtful redevelopment. It is a key component in achieving the City of Oakland’s vision under the Broadway-Valdez District Specific Plan to revitalize the neighborhood into a vibrant retail and mixed-use district. Once built, 3093 Broadway will contribute socially and financially to the neighborhood and overall East Bay community for years to come.
Answer provided by Christopher Glenn, PE, LEED GA, Senior Project Engineer
Christopher has 18 years of experience as an environmental engineer and project manager for investigation, mitigation, and remediation sites. He has a broad base of experience with numerous remediation technologies, including biological remediation (reductive dechlorination, aerobic bioremediation, bioaugmentation, bioventing, and natural attenuation), chemical remediation (Fenton’s reagent, permanganate, and zero-valent iron), and physical remediation (soil vapor extraction, air sparging, dual-phase extraction, groundwater extraction, and surfactant-enhanced extraction). Chris is a leader on sustainable engineering and is actively involved in Langan’s corporate sustainability initiative.