Meet Offsite: Overland Spill Modeling Automated
Planning is the key to accomplishing almost any endeavor. Want to get that diet under control? Plan ahead, prepping meals ahead of time when you know you will be busy. Want to squeeze more productivity out of the day? Schedule out your time, planning the most important or need-to-get-to’s to help "future you" get things done. Want to enhance your emergency preparedness and response practices? Plan, plan, plan.
One way to plan emergency preparedness and response is to model disastrous scenarios before they have had a chance to occur. Although this feat is quite complex, the complexity of modeling cannot stand in the way of compliance with regulatory requirements, public expectations, and general vigilance. With the extreme consequence of liquid leaks or spills, it is imperative that a land-based spill model be realistic. A comprehensive spill model is founded on proven algorithms that account for variations in surface cover, fluid properties, soil absorption, and terrain variations.
Do you have a spill model in mind? No? Well…hello there, I would like to introduce you to Integrated Offsite.
Overland Spill Model
Through review of various regulations and literature it is possible to determine the fundamental parameters required for modeling overland spills. These factors include terrain (or topography), drainage systems (natural or man-made), fluid properties, operating condition, potential release volume, and emergency response time. This listing is certainly not comprehensive and misses a few critical factors such as surface cover, soil properties, and weather conditions. These factors allow for flow resistance, soil absorption, and fluid evaporation to be included in the Overland Flow model.
Integrated Offsite envelopes this methodology, modeling liquid spills through inclusion of all factors defined by the regulations augmented by the suggested critical factors. Deployed as an Add-In for ArcGIS, this solution provides the tools required for this complex model.
The approach is based on rigorous methods for establishing realistic resistance to flow over the ground surface. It establishes a continuous surface of fluid flow resistance, considering variation in surface cover, slope (directional), fluid properties, and several other key factors. With resistance established, it calculates the path or paths a spill would make by passing over a topographic surface and accounting for resistance. These calculations can be constrained by defining upper limits on spill travel time, spill volume, spill area, or maximum travel distance.
Results and Reporting
Integrated Offsite is a specialized application used primarily to discern the spill travel time, tightly coupled with the spill area or spill travel distance. Depending on the constraints of the model, the results generated may represent potential spill travel paths or specific flow paths for the given scenario.
If required, fluid volume retained at any location can be calculated – adding yet another output from the spill modeling process. Results are dependent on fluid properties, soil absorption, evaporation, and more!
The example shown below is the result of calculating spill travel time from a single source with an unlimited amount of spill product. The example shows snapshots in time of the spill travel calculated from a single spill location.
This example highlights some of the features of Integrated Offsite. For instance, the model has chosen to flow over flat land, seek out valley bottoms, and move around hills, that is, the model knows not to flow uphill! Another feature of the model is its ability to show the relationship between spill travel time and spill travel distance. Looking at the 6 hour snapshots shows more distance traveled in the third 6 hours (18 hour window) because of the spill interaction with a river.
The main driver behind this Overland Spill model is to address the need of the oil and gas industry to meet their emergency preparedness requirements. However, the model behind Integrated Offsite has direct applicability to other industries and can also be used to help first responders with their planning process for emergency response times, establish effective emergency response control points, and estimate cleanup and remediation costs.