Former Hidden Valley Electronics Site – Angled Sonic Drilling and Injection

LaBella Associates teamed with the New York State Department of Conservation (NYSDEC) to complete an emulsified zero-valent iron (eZVI) injection application to treat chlorinated solvent impacts in groundwater at the former Hidden Valley Electronics site located in East Vestal, New York. The building associated with the site is currently used as a commercial health and fitness facility. eZVI is a remediation chemistry that consists of nanoscale zero-valent iron particles, a surfactant, food-grade vegetable oil ,and water that is used to reductively dehalogenate chlorinated hydrocarbons.

Overburden at the site is comprised of dense glacial till (with numerous boulders) that had precluded the use of conventional drilling and injection technologies. Angled rotosonic drilling methods were employed in order to penetrate the overburden and allow for the delivery of the eZVI to target remediation zones.

LaBella’s rotosonic drill rig was utilized to install five 4-inch-diameter PVC casings (80-feet in length) at 45-degree angles to extend beneath the building. These wells targeted a zone that extended approximately 55 feet laterally beneath the building footprint and 55 feet vertically beneath the ground surface. The entire 80-foot length of the annular space around the injection wells was grouted to prevent “daylighting” of the eZVI slurry once the target intervals were perforated and subsequent injections were underway.

Several injection technologies were reviewed with NYSDEC’s engineering consultant, and it was concluded that a patented waterjet, hydro-fracturing technology would be most appropriate for the site. This approach would include high-pressure waterjet cutting of the PVC, grout, and the surrounding glacial till formation so that the eZVI could be delivered to the targeted remediation zone via high-pressure hydro-fracturing methods.

Initial injections utilized highly pressurized water (10,000 psi) to cut perforations through the PVC casing/grout and into the surrounding formation. Each injection well was segmented into six to nine segments and perforations associated with each segment were completed using zone-isolating packers. Immediately following perforation, a total of 250 gallons of eZVI was injected at pressures of approximately 400 psi. The zone-isolating packers ensured that the turbulence from the injection mixed the eZVI slurry with the soil so that it penetrated deep into the formation.

During drilling and injection operations, real-time vibration and tilt monitoring of the building’s foundation and concrete floor was performed to ensure that the building was not damaged. Vibration and tilt monitoring instruments were designed and fabricated by LaBella at our facility in Ballston Spa, NY. These instruments were placed at discrete locations within the active health and fitness facility. The vibration and tilt monitoring verified that there were no disturbances to the site building during the drilling operation or associated eZVI application. Additionally, operations at the health and fitness facility were not interrupted during any aspect of the drilling and injection program.