Remedial Design & Construction

Developing “constructable” project plans and executing construction-based remediation at former manufactured gas plant (MGP) sites are trademarks of GZA. Since our entrance into the MGP practice, our personnel have designed and implemented a number of different remedies, based on subsurface conditions, that include: facility decontamination and demolition; support of excavation for deep cuts (steel sheeting, tie backs, and bracing); tangent and secant excavation techniques; dewatering; groundwater treatment; product recovery; in-situ chemical oxidation; groundwater cutoff walls with SB and CB mixes using slurry wall techniques; in-situ stabilization using augers, bucket mixing, deep soil mixing cutterheads, and chain mixing technology; jet and permeation grouting; engineered soil and sediment capping; real-time air monitoring systems; automated optical monitoring of adjacent structures; and sediment removal and site restoration.

Because a majority of MGP sites are located in or near residential communities, completing these projects requires a thorough understanding of the level of effort required to complete the construction, execute the technical objectives of the work, and interact with local authorities and the general public while keeping projects on-time and on budget. GZA provides Construction Management services for these challenging MGP projects. Our Construction Managers routinely have more than 20 years of experience managing demolition and/or remediation projects on As-Agent and At-Risk project delivery systems.