What the MSGP expects
Under the NPDES MSGP, industrial operators must inspect stormwater BMPs quarterly at minimum and document each inspection. Oil-water separators are the BMP inspectors focus on hardest. A full or bypassed OWS means hydrocarbons reaching surface water. That is one of the fastest paths to a compliance action.
Cadence in practice
- Monthly: visual inspection, oil-layer thickness measurement, sludge depth check.
- Quarterly: full vacuum pump-out of oil and sludge layers, water column recharge.
- Annually: coalescing plate cleaning or replacement, weir alignment check, structural inspection.
Disposal manifests are the audit trail
Every pump-out generates a licensed-hauler manifest showing gallons of oil, gallons of water, and disposal facility. That manifest, not the invoice, is what the state or EPA asks for at inspection. We file every manifest in the site's compliance binder and provide a scanned copy for owner records.
Common failure modes
Undersized separator for actual runoff volume (common on older sites), missing coalescing media, bypass line left open, and, most commonly, going too long between quarterly cleanings so the oil layer overtops the weir. See our Miami-Dade County page for local industrial notes.
