Q&A: Langan designs foundations for some of the tallest towers around the world. How does the firm provide its expertise in so many locations?

Kingdom Tower, Jeddah, KSA

Kingdom Tower, Jeddah, KSA

Langan’s core values of technical excellence, practical experience, and client responsiveness are desirable qualities that export well around the world. The technical excellence starts with a roster of geotechnical engineers that are trained at world class universities. This deep knowledge of soil mechanics, engineering geology, and foundation design allows us to apply fundamental and advanced engineering principles in any type of geology.

As for practical experience, it is essential when adapting to local construction equipment, workmanship, and materials. Many times, foundation options available in North America are not economically feasible in emerging economies.  We find that labor is less expensive compared to construction materials, where the opposite is often true in the U.S.

Last is client responsiveness. We find, especially in emerging markets, that few design teams can outpace Western project teams from concept design all the way through contract documents. Our international clients welcome this accelerated pace of work, because no matter where you are, time is money.

About Alan Poeppel, PE
Alan has over 20 years of diversified experience in geotechnical engineering projects involving the management, investigation, instrumentation, design, and construction of projects in the United States and overseas. He has spearheaded  a number of high-rise “super” towers projects in India and the Middle East including Kuala Lumpur City Center and the 1,000-meter-tall super structure, Kingdom Tower, in Saudi Arabia.

Q&A: What are the design considerations for landfill gas mitigation during site redevelopment?

Over the past two decades, the United States has seen a substantial increase in development on closed municipal-waste landfills. The construction value of these projects could be substantial in addition to the numerous end-use benefits such as tax revenues and new jobs. Redeveloping landfills is particularly challenging not only because of the issues associated with cleanup, but also because of the environmental and geotechnical issues of building on refuse. Landfill gas containing elevated levels of methane poses a significant risk of fire and explosion. Other landfill gases such as sulfur-based corrosives like hydrogen sulfide and volatile organic compound vapors pose significant exposure risks to human health, safety and the environment. Hydrogen sulfide can also cause significant odor issues.

Langan performed all aspects of monitoring, remedial planning, and landfill closure for this Contra Costa Waster Service NPL site.

Langan performs all aspects of monitoring, remedial planning, and landfill closure for various landfill sites.

To be effective, design strategies for mitigating landfill gas, must incorporate the site’s architectural, structural, and geotechnical features. Applying pilot testing and pneumatic air-flow computational modeling tools is good engineering practice to determine key parameters, including air intrinsic permeability of the refuse, radius of influence, well network, desired air-flow rates, vacuum propagation, and pore-air volume exchanges, for cost-effective designs and more reliable predictions of the mitigation system performance. Detailed evaluation of long-term remedial benefits, potential refuse settlement, seismic hazards, fire and explosion hazards, odor problems, and corrosive-gas impacts on the system constructability and performance should also be performed during the design phase.

Although redevelopment of landfills holds great potential, the means and methods used to design and implement gas mitigation systems are such that human health, safety and the environment are protected for the life of the project. Our ability to effectively remediate such sites means that redeveloping closed landfills for sanctioned use will continue for years to come.

About Omer Uppal, PE 
Omer has more than 15 years of experience in the environmental remediation and consulting industry. As Senior Project Engineer at Langan, he is responsible for soil, sediment, and groundwater investigations, field pilot testing, groundwater flow and contaminant transport modeling, risk-based closure and remedial strategy development, and full-scale engineering design. He is experienced in various remedial technologies including in-situ bioremediation, soil vapor extraction (SVE), multi-phase extraction (MPE), air sparging, chemical oxidation, treatment barriers, vapor intrusion, mitigation, and landfill gas mitigation systems.