One of the more difficult problems facing our cities is the reuse of former manufacturing facilities. In Seattle, WA, a former manufacturing site was contaminated with chlorinated solvents. Previous attempts to cleanup the site using pump and treat systems failed because the soils were heterogeneous, making it difficult to control the contamination. The owner and his consulting engineer decided that the technology with the highest probability of success for the site was a funnel and gate system using zerovalent iron to treat the groundwater. In 1999, reactive iron treatment was generally well accepted, but construction methods for its installation in deep trenches were still developing. As a result the owner, the engineer, and a slurry trench engineer developed and implemented an innovative plan to install a funnel and gate system up to 35 ft deep, using cement-bentonite (CB) slurry walls for the funnels and bio-polymer degradable slurry to install the iron-filled gates. One year after installation measured chlorinated solvent destruction efficiencies are greater than 95%. Downgradient from the gates, natural attenuation processes, including intrinsic biodegradation, are further reducing solvent concentrations to below surface water cleanup standards before reaching a public waterway less than 200 ft from the site.
Strength and Permeability of a Deep Soil Bentonite Slurry Wall
In 2006, a Soil Bentonite (SB) slurry wall was constructed at a brownfield redevelopment of a former steel mill site in Mayfield, NSW Australia. At this site, the slurry wall is designed to block groundwater