Oil/Water Separator
McChord Air Force Base, Washington
This project was for design of oil/water separators and grit chambers at six separate sites at McChord AFB. Drainage areas were primarily in highly industrialized areas of the base which had high potential for discharge of oil contaminated storm water to Clover Creek. Design included associated storm water runoff studies. Since the oil/water separators are installed in existing storm drainage systems, the projects involved changes to the existing storm drain lines and rerouting of some lines to collect and treat the maximum amount of storm water prior to discharge.
Waste filtration systems for the in-line treatment of stormwater were designed for six locations at McChord Air Force Base. Each location was an existing storm sewer system which outfalled to Clover Creek, a tributary to Puget Sound. All components of the waste filtration system needed to be placed underground and operate unattended; except for annual maintenance cleaning and monitoring of the waste oil.
Sizing of the systems was based on stormwater runoff calculations for the drainage basins, in combinations with the hydraulic capacities of the existing storm piping.
A mathematical analysis of oil and grit particle size distribution, in conjunction with typical concentrations for various flow rates, was used to determine the optimum sizing for the oil/water separators (OWS) at each location. Backwater calculations were required to determine the effect of high water at the creek on operation of the system so that the oil layer could not escape the system via backflow.
A concrete vault grit chamber, upstream of the OWS, provided grit and sludge settlement, along with trash retention, to assure the separator could function at high efficiency. The grit chamber also moderated sporadic storm flows to the OWS allowing large events to bypass the OWS and preventing damage to the system.
One system required design of a lift station.
Key Project Features:
- Hydrolic calculations
- Oil/water separators
- Design drawings
- Consruction support
