Estimated Burn System Potential (EBSP) Calculator User Manual

The ERSP, EBSP, and EDSP Calculators are intended as planning tools for estimating the potential of different oil spill response systems to mitigate (recover, burn or disperse) discharged oil relative to one another. These planning tools are NOT intended to be used as models for calculating system performance during an actual oil spill, which is affected by many factors such as the distribution of oil on the water surface, oil weathering, and other ambient on-scene conditions which are not included in these Calculators.

Prepared by BSEE and Genwest Systems, Inc.

February 2016

Contents 1. Introduction .................................................................................................................4 1a. Controlled Burning of Oil as a Response Option ..................................................4 1b. The EBSP Calculator’s Purpose and Intended Use ..............................................5 1c. Advancing Burning System Components and Definitions .....................................6 2. Assumptions and Limitations as a Planning Tool .......................................................8 3. EBSP Calculator Inputs ............................................................................................12 3a. Encounter Rate Inputs ........................................................................................13 3b. Fire Boom Inputs .................................................................................................15 4. EBSP Calculator Results ..........................................................................................16 4a. Tabular Result Definitions ...................................................................................17 4b. Simulation Notes and Errors ...............................................................................19 5. Using the EBSP Calculator .......................................................................................20 5a. Calculating EBSP for a Continuous Spill Scenario .............................................20 5b. Calculating EBSP for a Batch Spill Scenario ......................................................23 6. Equations Used in Calculations ..................................................................................27

1. Introduction The Calculator developed in this project accounts for the performance of an advancing controlled burn system as it encounters, concentrates, and burns oil inside of the system’s burn boom. The Calculator generates an “Estimated Burn System Potential” (EBSP) value in barrels of oil burned for each of the first three days following the instantaneous discharge of a batch oil spill, or daily for an ongoing continuous discharge of oil.

The EBSP Calculator is an HTML file, EBSP-160225. html, which runs in the following web browser versions:

PC (Win-XP, Win-7 and Win-8 environments) IE - 9, 10, 11 or greater Chrome 38 or greater Firefox 31 or greater Safari 5.1 or greater

Mac (OS 10.6 and greater) Safari 8.0 or greater Chrome 38 or greater Firefox 35 or greater

You can download the EBSP Calculator from the BSEE website. The “build” or version date of the calculator appears after the calculator name in the format -YYMMDD (see Figure 4). This date stamp can verify that you are working with the latest version of the calculator.

This User Manual provides additional guidance to the user on the various data inputs that must be entered into the EBSP Calculator regarding the burn system configuration being evaluated, and further explains the Calculator results.

The EBSP Calculator was developed by Genwest Systems, Inc. in consultation with U.S. Department of the Interior, Bureau of Safety and Environmental Enforcement (BSEE) and the United States Coast Guard.

1a. Controlled Burning of Oil as a Response Option During the response to the Deepwater Horizon Mississippi Canyon 252 Incident in the Gulf of Mexico approximately 220,000 to 310,000 barrels of oil were burned at sea in the completion of about 400 individual burns. Controlled burning of oil offers certain advantages over physical containment and recovery of oil and the use of chemical dispersants. It requires less equipment and personnel than these other response

techniques. Compared to physical containment and recovery, the storage and transport of recovered material is limited to the relatively small quantity of burn residue.

Fire-resistant boom concentrates oil/emulsion to a thickness that can be ignited and burned while the boom is being towed. Filling of the boom is facilitated by airborne spotters that direct the system to the heaviest concentrations of oil/emulsion. For safety, a full fire boom can be towed away from the spill site for ignition and burning. This is done by specifying an optional offset distance. After ignition the tow speed can be varied to control the progress of the burn. Nearly all of the oil is consumed, converting the oil to its primary combustion products of carbon dioxide and water with a small percentage of smoke particulates and other unburned and residue byproducts.

1b. The EBSP Calculator’s Purpose and Intended Use The EBSP Calculator is primarily a planning tool for estimating the potential for collection and burning of spilled oil by an advancing burn system. You can use the Calculator to evaluate the EBSP of a burning system for two kinds of spill scenarios:

• Continuous spills, such as a well blowout, in which oil is discharged at a steady rate for a relatively long period of time.

• Batch spills, such as a spill from a tank vessel, storage tank, or pipeline, in which oil is discharged nearly instantaneously or over a relatively short period of time.

To use the Calculator, you enter configuration information about an advancing burning system, such as its length, draft, and speed; you describe the circumstances of its operation, such as offset time from the collection area to the burn area (see Section 3, EBSP Calculator Inputs). The Calculator then estimates the amount of oil that the system could collect and burn during the operating period of each of the first three days after a major batch spill begins, or during the operating period for each day of a continuous spill response (see Section 4, EBSP Calculator Results). These estimates of the oil collected and burned are termed the “Estimated Burn System Potential” (EBSP) for the given burning system configuration. The use of the calculator tool in both spill scenarios is further demonstrated and explained in Section 5, Using the EBSP Calculator.

The EBSP Calculator was also developed with the intent of reinforcing incentives for creating and acquiring more effective oil burning systems. In addition to evaluating the potential of advancing oil spill burning systems to meet various regulatory planning requirements, you can also explore how to configure a burning system to best encounter and burn oil more efficiently. This experimentation is helpful in understanding the effects of different configurations on a system’s burn potential, and provides incentives for developing more effective burning systems.

1c. Advancing Burning System Components and Definitions

Figure 1. Advancing Burning System Components and Definitions.

The primary component of a burn “system” is the fire-resistant boom. There are several types of fire boom available including thermally resistant fabric booms, stainless steel booms, and water cooled booms. The EBSP Calculator does not differentiate between types of boom and uses only the length and draft of the fire boom in its estimates.

The ends of the fire boom are connected to towing vessels with bridles or tow lines. These bridles provide a safe working distance between the towing vessels and the leading ends of the fire boom and are typically about 300 feet long. Attachment of the bridles to the inboard side of the towing vessels minimizes the effect of vessel wake on collection and burning operations.

The towed fire boom forms a catenary into which the encountered oil/emulsion oil is concentrated at the apex. The length of the fire boom determines its holding capacity and the swath of the system as it moves through the oil slick. A boom is defined to be “full” or at its holding capacity (see below) when the oil/emulsion in the boom is 1/3 the distance from the apex to the leading ends of the boom and the average oil/emulsion thickness is 1/3 of the boom draft.

Not shown in the diagram, but included as part of the burn system, are aerial spotting components, the oil ignition team, burn residue collection/recovery operations, and any necessary command and control activities.

Enhanced Collection Configuration

Enhanced collection adds a U-shaped configuration of boom with an open apex towed ahead of the burn system. The added boom configuration increases the system’s effective swath width, and concentrates the oil/emulsion for containment and burning. This configuration increases a system’s areal coverage and oil encounter rates. Enhanced collection will require additional personnel, tow boats and enough additional boom to achieve the desired swath using a gap ratio of 1:3 (e.g. a 300 foot swath would require a minimum of 900 linear feet of boom).

Figure 2. Open apex enhanced collection configuration example

2. Assumptions and Limitations as a Planning Tool The EBSP Calculator was developed to provide an encounter-rate based estimate of daily potential for advancing burning systems operating in open waters, in warm or cold climates, without the effects of ice, debris or extreme weather conditions. The calculator accommodates a broad range of burning system configurations and addresses response activities including the accessing, containment and burning of oil. The goal was to provide a computer tool that could facilitate the calculation of a “Planning Standard”, not a “Performance Measure”.

The ERSP, EBSP, and EDSP Calculators are intended as planning tools for estimating the potential of different oil spill response systems to mitigate (recover, burn or disperse) discharged oil relative to one another. These planning tools are NOT intended to be used as models for calculating system performance during an actual oil spill, which is affected by many factors such as the distribution of oil on the water surface, oil weathering, and other ambient onscene conditions which are not included in these Calculators.

The following is a list of assumptions and limitations inherent to the design of the EBSP Calculator, that are readily acknowledged as conditions accepted in order to keep the Calculator a simple and easy to use planning tool:

• Default Values: Generally, conservative default values are built into the Calculator. A default value is conservative if it is more likely to be an underestimate than an overestimate. • Ambient Conditions: Estimates made by the Calculator assume that conditions are generally conducive to effective burning operations. Its output is designed to serve as a guide for planning the deployment of burning systems and estimating their potential in order to meet plan holder needs. • Ice: Burning in ice is not considered in the Calculator. • Asset Mobilization: It is assumed that the burning system is rigged and ready to operate at the beginning of each Operating Period. The EBSP Calculator does not account for the time necessary at the beginning of a spill for notification, mobilization, and transit time to the location of the oil slick. These factors need to be addressed separately in each plan as required by the relevant agency regulations. • Three Day Window for Calculating EBSP for a Batch Spill Scenario: The three-day EBSP calculation period for batch spill scenarios was selected for several reasons. After the first three days, there is a reduced availability of oil because the majority of the oil has weathered and spread to the point where continued on-water burning operations may become an ineffective response option. Another factor is the operational reality that three days after an incident has occurred, most of the necessary response resources would be on-scene or ordered, and spill specific response planning would be in place.

• Oil Types: The Calculator does not differentiate outputs based on the type of oil or product being burned. Its design assumptions most closely approximate the spreading and emulsion characteristics of Group II, III, and IV oils. As a result, the calculator is a less accurate predictor for the availability of non-persistent Group I type oils, such as gasoline or diesel fuel. Group I oils tend to NOT form stable emulsions. Group I oils also tend to form much thinner slicks than Group II, III, and IV oils even in very large discharge quantities. • Oil Spreading and Thickness Values: Computer models, such as the Response Options Calculator (ROC) developed by Genwest, along with other sophisticated models described in the EDRC project final report, were used to establish nominal oil thicknesses for each of three days following a major spill (typically thousands to tens of thousands of barrels). The ROC predicts that, in a batch spill, oil thicknesses within the slick generally will decline over time. The spreading and weathering of a broad range of oil types and volumes were simulated under varying wind/sea conditions and water temperatures. The analysis of the results of these simulations revealed nominal representative thickness values that are used to estimate the oil encounter rates for each day of a significant spill. The results of hundreds of computer simulations suggested that 12 hours after the discharge of a large oil spill (assumed mid-day on Day 1), the nominal oil/emulsion thickness could be estimated at 0.1 inch. The mid-day thicknesses for each of Days 2 and 3 could be represented by 0.05 inch (after 36 hours) and 0.025 inch (after 60 hours). Real-world oil/emulsion thicknesses can span several orders of magnitude for the many different oil types and environmental conditions that could actually occur during a spill. However, the three selected values reflect reasonable representative thicknesses which are used for the Operating Period in each of the first three days for the accessible portion of a batch discharge of oil for “planning” purposes. For significant continuous discharges, the nominal oil/emulsion thickness for the designated Operating Period in Day 1 (.1 inch) of a batch spill is used for each day of the response to a continuous spill. As such, the EBSP Calculator uses the same set of nominal representative thickness values for each of the three operating periods for an instantaneous batch spill (and the same repeating initial thickness value for each day of a continuous release) as the ERSP Calculator. Similarly, in the EBSP Calculator, the Operating Period is defined as the length of time in hours each day (centered on noon) where conditions allow a burning system to conduct operations. Using the same thickness values in both the ERSP and EBSP Calculators will allow for some direct comparisons between recovery and burning systems in their capacities to mitigate oil. • Collecting and burning in Waters with Restricted Maneuverability: The EBSP calculator does not discern between ocean or offshore operating areas and inshore operating areas. While the EBSP algorithms apply equally in all areas, burning systems with large swath widths are likely to be less effective in inshore operating areas, where water depths and restricted maneuverability are

likely to become a critical factor. It is up to the EBSP Calculator user to apply operational knowledge and common sense in selecting values for their burning configuration that match the needs of the operating environment (as opposed to entering values for poorly matched configurations that would maximize the EBSP at the expense of operational feasibility). • Use of Best Practices for Burning: The EBSP Calculator assumes responders will use best practices, for example, the use of airborne spotters and remote sensors in order to actively direct and keep burning systems continuously operating in the thickest available concentrations of oil. EBSP also assumes that personnel are available and trained to deploy and effectively operate the burning system in the manner necessary to achieve the maximum potential. • Air Monitoring: It may be necessary in certain situations to conduct air monitoring during a burn. This is not considered in the Calculator. • Boom Holding Capacity: The oil holding capacity of a boom is determined by its length and draft. The maximum holding capacity of a boom is assumed to be reached when the average thickness of the oil being contained inside the boom is approximately 1/3 of the boom’s draft. Collection of oil beyond this thickness may cause loss through entrainment. With the containment and burn area of the d/3 and the average thickness, the volume of oil in the boom can be estimated.

Figure 3. Boom Holding Capacity

• Burn Area: The Calculator assumes that the burn area will remain constant for a particular burning system configuration, and will be roughly equivalent to the surface area within the catenary of the fireboom located between the apex and points forward that are one third of the distance to the leading edges of the

fireboom being towed. In reality, the burn area will not be uniformly spread across this area and will change over time as the burn progresses. • Burn Rates: The Calculator uses the burn rates of 0.09 inches/min for the first Operating Period, 0.06 inches/min for the second Operating Period, and 0.04 inches/min for the third Operating Period (see Burn Rate equation in Section 6). These burn rates are based on the paper “The Use of Controlled Burning during the Gulf of Mexico Deepwater Horizon MC-252 Oil Spill Repsonse”, Allen et al, 2011, IOSC Proceedings. • Emulsification: Many oil releases involve emulsified oil (emulsions of water in oil). During real oil spills, emulsification proceeds at different rates and to different degrees depending on such things as oil type and environmental conditions. Based on a number of simulations, the Calculator specifies the percentage of emulsification as 35% in Operating Period 1, 55% in Operating Period 2, and 75% in Operating Period 3 for batch releases, 35% for all operating periods of a continuous release. EBSP is a calculated estimate of the volume of oil collected and burned. While EBSP data is provided for Operating Period 3 for planning purposes, it should be noted that successful ignition and sustained burning of oil that is 75% emulsified may be difficult or impossible to achieve in many circumstances. • Burning Outside of Containment: Several times during the Deepwater Horizon burn operations involved the safe and successful burning of oil immediately outside the fire boom. The volume of oil burned in this instance is difficult to estimate and is not included in the Calculator. • Burning Downtime: No downtime due to maintenance or repair is considered. • Completion of Final Burn that occurs between Operating Periods: At the end of each Operating Period it is assumed that any oil remaining in the burn boom will be burned before the next Operating Period begins. If the Calculator determines that this last burn cannot be completed in the time available between Operating Periods, then a Simulation Note (Simulation Notes are described in more detail below) will be generated - “Burn not achievable between Operating Periods - Reduce Operating Period [hrs]”. Using the same system configuration, the user can reduce the Operating Period and recalculate until the Note no longer appears. • Collection of Burn Residue: At