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.


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


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.

What are your top tips to best manage the risks of contaminated fill during construction projects?

Tip #1: Know that there are risks and liabilities for the owner, developer, contractor and consultants.

Management of known or potentially contaminated fill (and recycled material/debris) poses risks and liabilities to all involved: owners, developers, contractors, and consultants.  There are federal, state, and often local regulations and requirements that apply to managing fill and recycled materials. The site owner, developer,  contractor, and even the consultant who were involved in generating and arranging for the management of exported fill/materials could be liable for its handling and management under federal and state law.

Tip #2: Assess the likelihood of contaminated fill on your project at the outset in the concept development stage.

Construction contracts often presume that excess soil and demolition debris represents only a nominal cost or is viewed as a commodity in the bidding stage of a project. Completing a Phase I Environmental Site Assessment in compliance with the ASTM standard is prudent and can offer some valuable information and liability protection, but is not always adequate to assess potential project impacts related to managing potentially contaminated materials.  Understand the cut/fill balance well in advance of contractor bidding and construction.

Tip #3: Plan ahead to minimize costs and delays.

A fill management plan incorporated into project bid documents, contracts, and construction documents designates responsibility and can be used to allocate costs. Characterizing fill early allows time for practical solutions such as treating material in place or in piles, segregating and routing material to lower cost facilities, consolidating/blending material on-site or re-working the site design. Insuring that your bidders have reviewed the plan and are experienced in the management of fill will get you a price without an “uncertainty premium” (high rates to buffer unknowns) or overly broad exclusions that lead to change orders.

Answer provided by Jeff Smith, PG, Associate
Jeff has over 24 years of experience with property assessments, pre-remedial investigation and strategy, RI/FS, FD/RA, alternative remedial strategies, amended RODs, and exposure pathway and vapor intrusion assessments. His career has required the mitigation of complex technical, regulatory, and legal issues, resulting in development of alternative, cost-effective, practical solutions to environmental problems.

Successfully Integrating Land Development and Environmental Requirements


Here are some real-world examples that illustrate the benefits of a multi-disciplinary approach that enables better communication for successful projects.

  • A remedial plan that called for a 2-foot “clean fill” cap on a project would have resulted in a net soil export cost of $250,000. Langan’s team of site/civil and environmental engineers and landscape architects reduced the export by revising the site grading strategy, limiting the cap area, and developing a soil profile that allowed for reuse of site soils as planting soil in areas not requiring a cap.
  • On another project, regulators initially required that stormwater not be infiltrated through contaminated soils prior to recharging the groundwater. The Langan environmental,  geotechnical, and site/civil teams worked together to evaluate soil characteristics and use synthetic precipitation leaching analysis to demonstrate that contaminants would not be flushed by infiltration and reach the groundwater below. The project design team strategically oriented the proposed buildings over “hot spots” and optimized green infrastructure features including a green roof, bioswales, and an underground detention tank. These solutions allowed stormwater to be managed on-site per the local regulatory requirements.

owner-developers-chartOf course, at Langan, we provide the essential technical disciplines, so we know firsthand the value our integrated services model brings to clients. In each of the scenarios above, proactive communication between team members avoided delays and unnecessary costs.

How can you foster communication on your projects?

One key way to promote communication is to get the team together to plan. Ask them to identify competing priorities, such as the contractor’s need to promptly backfill an excavation vs. the consultant’s need to collect samples. Another technique is to request a detailed review of bid documents, plans, and specifications from each of your team members with specialized knowledge. This gives them the chance to point out connections and critical path items that may have been overlooked. Stress the importance of your entire team working closely with your environmental consultant. Collaboration produces the best solutions.

What were the geotechnical challenges of working on the One South Market project?


One South Market site during construction

One South Market is one of the latest high-rise buildings to fill the skyline of downtown San Jose in the last few years. In the past, the City of San Jose has encountered difficulty attracting developers to bring new tall building projects into downtown.  Due to downtown’s close proximity to the aircraft flight path to Mineta San Jose International Airport, the San Jose 2040 General Plan states that all new tall building heights be subject to maximum building height limitations as mandated by Federal Aviation Administration regulations.

In order to make the project economically feasible with the building height limitations, the developer of One South Market conceived a plan that included a 23-story tower of luxury condominiums and a six-story parking structure located next to the tower.  The tower was constructed at-grade, while the parking structure was constructed with a three-level basement.  Langan worked with the design team to evaluate the settlement compatibility between the two buildings and optimize the foundation system to support both structures.


One South Market

Challenges for this project included installation of temporary shoring to support the 38-foot excavation for the parking structure. The temporary shoring protected surrounding buildings and city streets and allowed for management of the dewatering of the shallow groundwater during construction. The temporary shoring consisted of soldier-pile and lagging with tieback anchors; however internal steel beam walers and rakers were used for a nearby historic building. Installation of soldier piles included vibrated-in piles and drilled piles near existing structures to reduce vibration impacts.

It was very rewarding to be part of this project team, assist with the design and building’s LEED silver certification and to be a part of the future growth of downtown San Jose.


Answer provided by Gabriel Alcantar, PE, Project Engineer
Gabe is experienced in performing geotechnical evaluations and managing construction projects throughout the San Francisco Bay Area.  As a project engineer, he works on projects involving shoring systems, mass grading, installation of deep and shallow foundational systems, and  ground improvement. Additionally, he performs probabilistic hazard seismic analyses for projects within California and internationally.

What specific technical challenges affect successful land development in LATAM?

Water and earthwork! Almost every new site we see (other than urban infill) is pushing the edge of the developed area or is just out there – call it sprawl or starting a whole new remote community. The edge of the developed area is the edge more than likely because it has hilly terrain and needs a lot of earth movement. We get involved at the concept or master plan stage, take the project vision and test out the earthwork costs, and then we steer the project’s vision in a more cost-efficient direction.


Langan provided site/civil, geotechnical, hydrogeological, and traffic engineering for Serena Del Mar in Cartegena, Colombia.

With the remote sites, city water is usually not there or not practical to bring in from afar, so you need to develop your own water supply. On an island, that’s likely going to be using seawater, but on the mainland areas, we are generally going to be drilling wells. Just make sure to use competent hydrogeology well testing, design, installation, and development for a sustainable well supply or else the simple method of drilling a hole and dropping a pump will lead to starting all over again in a couple of years.

Answer provided by Eric Schwarz, PE, LEED AP
Eric specializes in site/civil land development engineering, hydraulics and hydrology, storm drainage, water distribution and sanitary sewerage conveyance design. During his 20 years at Langan, he has managed dozens of major projects throughout Latin America.