Stormwater Separator Cuts OWS Size

The Problem: Provide economical stormwater protection from aboveground storage tank spills in conformance with NPDES regulations at a large U.S. bus storage-and-maintenance facility. The project also had to comply with the regulations of the U.S. EPA, Westchester County Department of Transportation, the U.S. Army Corps of Engineers, and the Department of Energy Conservation.

Oil-water separators have been used in similar situations for many years. However, the initial investment (as well as the operating costs of an oil water separator [OWS] unit) is relatively high. The system also is complex, requiring extensive maintenance.

The Solution: Use an innovative Best Management Practice (BMP) to reduce overall costs by pre-treating runoff water before it enters conventional oil water separator (OWS) equipment.

The Liberty Lines Bus Company's primary objective was to prevent stormwater runoff pollution from a 10-acre bus storage-and-maintenance facility in Yonkers, NY, from flowing to the environmentally sensitive Saw Mill River.

Project planners recognized that significant cost savings would accrue if they could reduce the size of the OWS.

The solution proved to be the installation of an STC 2400 Stormceptor unit ahead of the OWS. The Stormceptor removes as much as 80% of TSS and more than 95% of such hydrocarbons as gasoline, oil, transmission fluid, and grease.

Moreover the design of the Stormceptor made it easy to install.

The unit consists of an upper bypass chamber and a separation/holding chamber. A fiberglass weir divides these chambers. Stormwater flows into the upper bypass chamber and is diverted by the U-shaped weir through a drop inlet pipe. It then runs into the treatment chamber where gravity causes fine and coarse sediments to settle to the bottom of the tank.

Oils rise in the treatment chamber where they are trapped. An internal bypass system prevents scouring of previously trapped materials during periods of high runoff flow. Surface access allows contaminants to be removed by a vacuum truck, approximately once a year.

CSR Hydro Conduit, Pittsburgh, PA, manufactured the 2400-gal Stormceptor. CEA Engineering, PC, Bardonia, NY; engineered the overall project.

Contact: Stormceptor Corp., 600 Jefferson Plaza, Suite 304, Rockville, MD 20852. Tel 800-762-4703; Fax: 301-762-4190.

Edited by Paul Hersch