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

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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?

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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.

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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.

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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.