Case Studies

Cement- Bentonite Soil Removal and Replacement Former MGP Plant at Newcastle Street Brunswick, GA

Project Summary

This project involved the mass removal of MGP impacted soils using the CB slurry wall method. The site was situated across the street from ocean-side boat docks and across the property line from residential homes. The site occupies less than half a city block. The utility companies wanted to remove or treat the impacted soils without impacting the neighbors or dewatering the site to a depth of 40 ft. Initial proposals included insitu stabilization and solidification (or deep soil mixing) and a sheeted excavation, but these were rejected. Geo-Solutions proposed a CB excavation which met with regulatory approval and addressed owner concerns. Geo-Solutions teamed with SBX, a local general contractor with soil remediation expertise.

Planning for the site works involved a number of tasks. In order to reach a maximum depth of 40 ft, the general contractor planned to remove the overlying 10 ft of soil, using a solider-pile and lagging system to retain critical utilities. Geo-Solutions developed a CB mixture which met workability and performance criteria, which included permeability and strength requirements. Finally, Geo-Solutions and the general contractor developed a sequence and layout of panels that ensured the removal of the soils and addressed workability concerns.

Geo-Solutions mobilized our medium grout mixing plant (see picture above). This smaller plant fit into the tight confines of the site and produced the necessary CB (cement-bentonite) slurry. Due to the required depth, Geo-Solutions also provided a long stick to mount on a local hydraulic excavator. The long stick excavator also provided the extra reach necessary for efficient staging of impacted soils for stockpiling and disposal.

The project work consisted of excavating up to 3 CB panels per day, each 5 ft wide, 30 ft deep and up to 30 ft long (see picture at left). The impacted soils were quickly drained, treated as needed with a drying polymer and loaded onto trucks for transport to the landfill. Once the project was full swing, the capability of the landfill to accept wastes and the availability of trucks drove the project schedule. The capability of the medium CB plant was never exceeded.

Geo-Solutions completed the project on schedule and within budget. The neighbors were pleased that "the site" was finally completely remediated. The site is now being developed for commercial development. The hardened CB provides adequate foundation support for the new development and encases any minor amounts of contamination that may have escaped the concentrated removal effort.

Geo-Solutions Can Help

To download, read, and learn more about the various slurry wall sample specs and technical papers we offer online here at Geo-Solutions.com, click on the links below or to your left:

• Slurry Wall Sample Specs– Geo-Solutions provides slurry wall sample specs which can be modified for real world use on your project. Download sample specification for Slurry Wall Construction.

• Slurry Wall Technical Papers – Browse our library of Slurry Wall Technical Papers.

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