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Ecommerce Warehouse

Clay, New York

Stormwater Treatment


Langan Engineering


Smith Site Development


September 2020

Technical Description:

  • (7) Cascade® Separators 

A massive 3.8 million square foot distribution center was built on 111 acres of land in Clay, NY. The facility is the second-largest building of its kind in the world, where employees work alongside robots engineered to pick, pack and ship small items like books, electronics and toys.

The project was considered new development per NYSDEC and required both pretreatment and treatment of the water quality volume. While there was enough land space for bioretention systems to meet the water quality and runoff reduction requirements, 100% pretreatment was still needed for permitting. Thus the engineer needed to include a manufactured treatment device in the overall stormwater management system design.

The biggest challenge was the enormous pretreatment flow of just under 95cfs. The EOR needed a solution to accommodate the high flows and reduce the size and cost of the pretreatment systems for the owner. Contech worked closely with the engineer to propose seven Cascade Separator units installed at five locations throughout the site. Two locations used a parallel unit configuration to accommodate the large flows. The Cascade Separator is a hydrodynamic separator (HDS) that uses advanced sediment capture technology to provide the highest sediment removal efficiency of any Contech HDS product. In addition to system sizing, Contech engineers also analyzed system depth and bypass for peak flows. Using the Cascade Separator, the engineer could substantially reduce the size of the HDS systems needed at the site.

The installation of the Cascade separators took place over three days in September 2020. A crane set the 10-foot diameter Cascade units, while an on-site excavator set the 8-foot diameter units. A Contech Stormwater Field Consultant was present during the installation of each unit to assist the contractors and ensure proper installation.

Technical Description:

  • (7) Cascade® Separators 

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