Following identification of the problem, WSP designed, installed, and maintained an in-situ chemical oxidation system using ozone. The design included a network of 19 delivery point clusters installed in three subsurface zones, an ozone conveyance network, and an ozone generator housed within a dedicated enclosure. The design also included waste minimisation practices to avoid disposal of characteristically hazardous shallow soils. Priority was given to minimising interference with site operations during all aspects of the installation and maintenance of these systems, including completing work during off hours.
Reductions of methylene chloride concentrations of more than 75% and 99% have been achieved in the shallow (high concentration) zone and deeper zones, respectively. Above-grade conveyance system runs minimised trenching and hazardous waste generation and disposal costs.
The use of practices to minimise interference with site operations led to no downtime for the facility and no increase in costs for the client. WSP’s remedial approach of in-situ chemical oxidation significantly decreased the methylene chloride and other volatile organic compound (VOC) concentrations without interfering with the existing manufacturing operations.