How did Langan implement a successful sulfate delivery system for remediation at 3093 Broadway?

Remediation is a critical component for brownfield redevelopment and this project at 3093 Broadway in Oakland, California is no exceptioAdditional boreholes 2n. 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.

IMG_0751We 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.

What are some of the challenges for new capital projects at existing refineries?

Challenges for new capital projects at existing refineries usually include permitting, below-ground constructability, waste soil management, and health and safety.refinery

Permitting can be a critical path issue, and should be initiated as early as possible in the project design, during pre-permitting meetings with the regulators.  Identification of regulatory jurisdictions early in the planning stages can provide valuable information in siting new facilities. Shoehorning in a new piece of equipment at the refinery requires an in-depth understanding of the subsurface conditions.  This includes identifying utilities and environmental hazards and taking appropriate safety considerations.  The geo-environmental approach works best where the geotechnical and the environmental borings are combined, meaning the holistic solution to the installation of the foundation involves both geotechnical and environmental considerations.

Understanding the constraints of utilities, the potential shoring of utilities, and the handling of the waste soils during construction is critical at the early stages of design development, and may influence selection of foundation type.  The requirements for dewatering, the treatment of the water (whether it can be discharged under the existing permit to the refinery wastewater treatment system), potential migration of existing plumes, and the health and safety issues are all items that require consideration during design.  Ultimately, the design requires a detailed constructability review to confirm that all safety, environmental, risk and engineering issues are covered prior to the completion of the final design.

Answer provided by Rory Johnston, PE, BCEE, Principal
Rory’s consulting career spans almost 30 years, ranging from geotechnical engineering on large industrial projects to environmental investigation and remediation. At Langan, a key part of his role as a Principal is to lead major projects in various market sectors, with an emphasis on oil and gas projects.

Successful Refinery Remediation Requires Special Expertise

LNAPL remediation requires understanding oil refinery history, knowing how to work within current-day operational constraints, and expertly applying the latest science. Oil refining in the modern era dates back to the mid-19th century. Many facilities have been built, rebuilt, and expanded several times to accommodate different product demand and evolving refining technology over this 150-year time period.

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Remediation taking place at an oil and gas site

Here are a few of the challenges related to the historical nature of refineries that require an experienced team to successfully recover LNAPL:

  • Variable composition of LNAPL poses different remedial challenges. Older LNAPLs tend to be more viscous or weathered and are typically hard to extract, while fresh fuels often have larger extents due to higher mobility. When older and newer materials comingle, specialized remedial approaches typically need to be leveraged.
  • Groundwater levels are often more variable than at other sites. In addition to the typical seasonal and long-term level fluctuations from climate, refineries have multiple water sources and large differences in use over time that have raised and lowered water levels, which can leave more trapped or stranded pockets of LNAPL at refineries that are less accessible to recovery efforts.
  • Dense development poses access limitations. The location of aboveground structures and below ground obstructions at refineries often limits access for recovery points.
  • Safety requirements take precedence over remediation. Process hazards within an active refinery are paramount, and often limit site access and restrict use of some viable remedial approaches.

Optimizing Remediation Efforts and Saving Money

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Environmental Remediation

Our remediation specialists have had success internationally using an approach that leverages traditional LNAPL extraction scenarios, augmented where practical, with technologies from other engineering disciplines. Some innovative Langan approaches include the removal of LNAPL via mobile vacuum enhanced solutions, which allows for a focused remedial approach without a large capital investment, and utilizing “air-lifting” for deep and submerged vertical zone treatment, as typically used for development of deep water wells.

LNAPL remediation requires more than the latest technology. A successful effort must leverage proactive regulatory programs centered around risk-based criteria, extraction practicability discussions, and evaluation and documentation of immobility―while still being focused on the needs of the client. For example, eliminating the LNAPL that accumulates in wells and causes the biggest perception concerns can reap big benefits for clients.

“Our hybrid approach to LNAPL recovery utilizing both innovative and tested methods, delivers remedial solutions with minimized disturbance to ongoing operations.  Also, our fit-for-purpose strategies and regulatory advocacy results in desired business outcomes, meaning the main objective―closures,” says John Loeffel, Langan LNAPL Remediation Specialist.

Time and cost savings are achieved by confirming the source and long-term fate of hydrocarbon impacts, focusing on an end goal determined through revised conceptual modeling, limiting installation of permanent systems or new wells, and receiving stakeholder “buy-in” before commencing an extraction plan. A successful remediation team understands the challenges of refinery work and is focused on delivering a safe, effective solution that delivers on the client’s objectives.