|Contract Value||$1M - 5M|
|GWTT Role||System Install, Civil Work, Design Support, I&C|
GWTT was contracted to construct a seep collection and treatment system adjacent to a historic industrial landfill at an active manufacturing site in Schenectady, NY. The system was designed to recover groundwater containing metals (primarily iron) migrating from the landfill into down gradient surface water to mitigate aesthetic and ecological impacts. Three seep collection systems consisting of HDPE pipe, stone and recovery sumps with electric sump pumps were installed to intercept groundwater. The well vaults were 6-ft precast diameter concrete vaults installed with aluminum
access doors. More than 1,800 feet of 3” HDPE and 160 feet of 4” HDPE pipe was installed to construct the seep collection and conveyance system.
GWTT installed a system to treat the recovered water within a 36’ by 85’ pre-engineered building installed on a mat style foundation. Due to landfill debris in the building location, more than 50 ductile iron friction piles were installed to bedrock depths to support the foundation. The building was completed with heat, lights, and ventilation. The treatment system includes process tanks and pumping equipment, a clarifier, chemical feed equipment, sand filters, bag filters, carbon adsorbers, compressed air system, sludge dewatering equipment and all related instrumentation and PLC-controls.
An added feature to the remediation system is a sulfate injection system designed to mix and add magnesium sulfate to a series of 18 combination
extraction/injection wells via a fully automated pumping system that utilizes PVC eductors to provide vacuum for the extraction cycle. While nearly 3,000 linear feet of 1” HDPE conveyance pipe was installed, the system features just 3 recirculation pumps to pump and inject water based on any operator-selected combination of extraction and injection.
Key Project Details:
- Design flow rate of 60 GPM
- GWTT served as General Contractor responsible for all well drilling, civil, building, mechanical, process, electrical and instrumentation and controls work
- 36’ X 85’ Pre-Engineered Steel Building erected on a mat foundation supported by more than 50 friction piles.
- GWTT-engineered sulfate mixing, injection and extraction system utilizing 3 pumps and venturi style eductors
- Chemical systems for pH adjustment, coagulation, flocculation, and sludge conditioning
- Primary treatment components are a clarifier, sand and bag filters, and carbon adsorbers
- Sludge dewatering utilizing geotubes and dewatering boxes
- Three seep collection structures with extraction sumps and 18 injection/extraction wells
- Aggressive implementation schedule required to meet regulatory deadline.
- Working at the edge of a historic industrial landfill, many unexpected subsurface conditions were encountered and addressed during construction.