In-Situ Treatment

Key Advantages

• Minimize removal volumes (with all associated costs).

• Provides 100% clean surface for restoration – Eliminates risks associated with residual contaminant levels.

• Reduces risk of recontamination from other sources, such as upland seep zones.

In-situ treatment has been defined by the industry in several ways. Usually, in-situ treatment refers to the use of reactive or adsorptive materials in small amounts on the sediment surface for the reduction in contaminant concentrations in the biologically active zone (BAZ).

Reduction in contaminants is evaluated by pore water measurements, considered the most bioavailable contaminant. Materials on the sediment surface are thought to mix naturally into the BAZ, resulting in desired reduction.

AquaGate®+ materials have been applied successfully in both pilot and full-scale implementation of in-situ treatment. Most applications involve the use of powdered activated carbon (PAC) placed in very thin lifts (1-2 inches).

An example of results from a similar project are shown below. In the pilot study, PCB pore water concentrations were reduced over 90% following application of a 2-inch layer of AquaGate+PAC, delivering a loading of approximately 5% activated carbon, by weight, within the upper 6in of sediment.