Non-Floating Oil Assessment Tool
Washington State Maritime Cooperative
Rapid Sinking Risk Assessment for Oil Spill Response
The WSMC Non-Floating Oil (NFO) Assessment Tool provides incident commanders and spill responders with an immediate, science-based determination of whether a spilled oil is at risk of sinking. The tool calculates oil and water densities at current environmental conditions, forecasts density changes from evaporative weathering, and evaluates sediment interaction risk to produce a defensible HIGH, MODERATE, or LOW sinking risk classification.
How It Works
Select Oil & Conditions
Choose from 1,456 oils in the NOAA ADIOS database or enter properties manually. Specify water temperature, salinity, air temperature, wind speed, and sediment load.
Automated Analysis
The tool calculates water and oil density, forecasts evaporative weathering using the Fingas (2004) model, and predicts when (or if) the oil may exceed water density and sink.
Risk Report
Receive a classified risk level (HIGH / MODERATE / LOW) with a detailed explanation, evaporation forecast table, recommended response actions, and a downloadable PDF report.
Scientific Foundation
- UNESCO EOS-80 seawater density equations
- PyGNOME-consistent thermal expansion model
- Fingas (2004) evaporation model with 15°C reference
- Mass-conservation density forecasting
- Oil-mineral aggregate (OMA) sediment risk
Operational Features
- 1,456 oils from the NOAA ADIOS library
- Evaporation forecast out to 120 hours
- NOAA lab weathering data when available
- Downloadable PDF report for documentation
- Manual entry mode for unlisted oils
Regulatory Context
Under RCW 88.46 (Vessel Oil Spill Prevention and Response) and WAC 173-182-324, Washington State contingency plans must address the potential for spilled oil to become non-floating. Non-floating oil poses unique challenges: conventional boom and skimming equipment cannot contain or recover submerged oil, requiring specialized detection (side-scan sonar), monitoring (water column profiling), and recovery (dredge, vacuum, pumping) techniques.
This tool enables the required one-hour assessment by automating the density calculations, weathering predictions, and risk classification that would otherwise require manual computation and reference to multiple data sources. All scientific methods are documented in the tool's Scientific Methodology page.
No login required. Free to use for all spill responders.