CA005 – Ferox™
Figure 1: Downtown Sunnyvale, California
In the summer of 2008, ARS was subcontracted to implement the Ferox™ technology in remediating the groundwater in downtown Sunnyvale, California as part of a redevelopment plan to transform the area into a high-end retail/residential space.
The scope of the project included conducting Pneumatic Fracturing (PF) and Atomized Liquid Injection (ALI) of micro-scale, Zero-Valent Iron (ZVI) in 56 injection boreholes in order to mitigate PCE contamination that was associated with past historic dry cleaning operations.
The injection boreholes were advanced by ARS’ newly acquired Geoprobe 8040DT rig down to a depth of 65 ft. bgs. PF and ZVI injections were performed between the depths of 60 ft. and 30 ft. bgs. Approximately 12,000 lbs. of ZVI were injected into each boring. A total of 672,000 lbs. of ZVI powder were injected during the 2.5 month field duration. The fracturing initiation pressure ranged between 100 and 300 psig while the ZVI injection pressures were typically less than 200 psig after fracturing.
Figure 2: Downtown Sunnyvale, California
Because of the location of the work and the amount of equipment required to implement the project, ARS worked closely with its client in planning and executing the field logistics to minimize disruption to the local residential and commercial communities who host a weekly farmer’s market and music festival adjacent to the work area, in addition to the bustling shopping and restaurant scene. The project was completed on schedule and within the allotted budget. Groundwater monitoring results in the “hottest” well showed a 94% reduction in PCE three months after the completion of the injection activities from a baseline of 1,800 µg/L to 170 µg/L, post-injection. Additional groundwater monitoring is taking place as the PCE mass reduction is expected to continue.