Pilot Test & Soil Vapor Extractions
Project Name: Capital District Plastic Product Manufacturer
Project Duration: 2005 - Present
Impact Characterization: Historic releases of chlorinated solvents, resulting in an adverse impact to the subsurface soil and groundwater regimes beneath a Plastics manufacturing building.
Technical Overview: The goal at this site was to reduce chlorinated solvent vapors and to create a vacuum within the sub-slab soils as a vapor intrusion control focusing on extracting vapors via soil vapor extraction wells to be installed through the facility’s concrete slab floor at eight locations.
Remediation pilot test equipment was supplied and operated in December 2005 by PES, to obtain site-specific information regarding the function and effectiveness of soil vapor extraction (SVE) wells.
PES installed eight 4” diameter, shallow, low vacuum, soil vapor extraction wells within the subsurface contaminant plume areas as defined by the client. Two remedial system enclosures were provided and installed to house each of two skid-mounted remedial systems. Each remedial system enclosure houses a soil vapor extraction blower, moisture knockout drum, and an integrated control panel. Significant coordination was required to properly deal with issues arising from site specifics such as performance of trenching and drilling within the floor and working overhead on man-lifts within an active manufacturing facility.
The SVE wells were connected to the remedial enclosures via below and above ground steel and schedule 80 PVC piping. Schedule 80 PVC piping was installed in the trenches and in the vertical runs from above the ten-foot steel interval (grade to ten feet) to the ceiling mounted headers. Piping trenches were backfilled with pea-stone and capped with 4,000-PSI concrete. The replacement concrete consists of a separate monolith pour, which was finished to correspond to the existing floor height.
Each SVE well is equipped with an airflow gauge and a vacuum gauge to allow monitoring of remedial system performance at each of the eight extraction wells. Low vacuum applied to each SVE well will induce vacuum to the geologic formation beneath the concrete floor slab to enhance vapor migration to the SVE well and to induce a vacuum to the sub-slab. The sub-slab vacuum is required to prevent vapor intrusion from the subsurface into the Plastics manufacturing facility. Vacuum and airflow may be modified at each SVE well via valve adjustments.
Moisture within the extracted vapors is separated at the remedial system via moisture separator tank. The liquid-phase fraction is stored within the moisture tank pending proper disposal. PES performed the required work, even with several change order situations, within the time and budget framework for this site.
Site Progression Specifics: SVE pilot testing at this site was initiated in December 2005. The two remedial system installations were completed in June 2006 and the systems were activated on June 23, 2006. The NYSDEC and NYSDOH mandated systems have remained active and have functioned as designed since activation with greater than 99% operating efficiency.