In
Brief:
| Oil-grit separators are large cast-concrete containers subdivided by one or more baffles, buried below grade. When configured to receive outflow from catch basins, they provide additional treatment of stormwater runoff by capturing suspended particulate matter, oil and grease, and floatable debris. A hood or an inverted elbow was not installed over the outlet of the second chamber of the separators in this study. A baffle separated the primary chamber from the secondary chamber, and contained three circular 12-in. outlets 1.5 ft from the chamber floor. Each separator included a bypass pipe that carried flow past the device during intense runoff by use of a diversion weir placed near the inlet of the separator. Although this design feature allows untreated stormwater to bypass the separator, it theoretically prevents extreme flows from flushing captured materials from the separator. All drainage pipes are 1 ft in diameter and accessible through manholes.
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