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, which 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 — the most common — going too long between quarterly cleanings so the oil layer overtops the weir. See our Hialeah and Doral pages for local industrial notes.
