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Introduction

In 1989, the Exxon Valdez spilled over 11 million gallons of Alaskan crude oil into the Prince William Sound. The events that followed, namely the mass cleanup efforts and environmental damages, revealed that the United States was inadequately prepared for a major oil spill response. However, the Oil Pollution Act of 1990 (OPA 90) and Executive Order 12777 (White House, 1991) helped address this deficiency through the implementation of regulations related to the prevention of, response to, and financial responsibility for oil spills within the navigable waters of the United States. Some of the safeguards provided by OPA 90 included mandating contingency planning and setting new requirements for vessels and crew. OPA 90 also mandated that response resources be identified and contracted, in advance, for both facility and vessel oil spill response plans. Specific resource requirements, and the method for calculating the same, are outlined in regulations that can be found in multiple sections of the Code of Federal Regulations (C.F.R.), depending on the regulatory agency responsible (e.g., 33 C.F.R. Part 154 [United States Coast Guard], 40 C.F.R. Part 112 [Environmental Protection Agency], 30 C.F.R. Part 250 [Bureau of Safety and Environmental Enforcement], and 49 C.F.R. Part 192 [Pipeline and Hazardous Materials Safety Administration]). These regulations make frequent reference to Oil Spill Removal Organizations (OSROs), companies that specialize in cleaning up oil spills and, if U.S. Coast Guard (USCG) classified, can be used by facility and tank vessel response plan holders in their response plans in place of an extensive list of response equipment and resources.

The planning standard for mechanical oil-skimming systems in the United States, developed as part of a negotiated rulemaking process following the enactment of OPA 90, is the Effective Daily Recovery Capacity (EDRC; Casey and Caplis, 2014). The EDRC is a measurement of how much oil a skimmer can collect per day following an oil spill and is calculated by multiplying the manufacturer’s daily rated throughput capacity by 20 percent¹ (33 C.F.R. Part 154, Appendix C; USCG, 2021c). After the 2010 Deepwater Horizon oil spill in the Gulf of Mexico, EDRC was deemed inadequate for calculating mechanical oil recovery spill response equipment needs. Critics noted that the EDRC methodology failed to consider key factors such as encounter rate (USCG, 2021b) and should account for the entire skimmer system, not just an individual skimmer component such as pump nameplate capacity (Casey and Caplis, 2014).

In 2012, the Bureau of Safety and Environmental Enforcement (BSEE) commissioned Genwest Systems, Inc. (Genwest) to assess the EDRC planning standard and to consider improvements or alternatives. In their report, Genwest proposed an alternative performance-based method or “tool,” known as the Estimated Recovery System Potential Calculator (BSEE ERSP Calculator), to estimate the recovery potential of skimming systems under variable environmental and operational conditions (Genwest, 2012). The authors developed a set of algorithms, involving key oil spill recovery operations (e.g., surveillance and spotting, staging, and response time), and selected input parameters (e.g., Nameplate Recovery rate, Onboard Storage, Recovery Efficiency, Throughput Efficiency) so that the model’s output could aid in the creation of a novel and operationally meaningful planning standard (Genwest, 2012). Unlike the EDRC, which uses only the nameplate rating of the skimmer to determine recovery, the BSEE ERSP Calculator treats the “recovery system” (e.g., boom, skimmer, and storage) as a unit being operated in a defined manner (e.g., swath width, advance speed, encounter rate, and operating hours) to determine the system’s recovery

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¹ The 20 percent efficiency, or derating, factor was determined by an Oil Spill Response Plan Negotiated Rulemaking Committee. The derating factor was included to account for the various, data-limited conditions on which effective skimming capacity depends. These data-limited conditions, where there was not enough information to specify or evaluate each, include efficiency of the oil/water separation process in the skimmer, oil viscosity, debris presence, skimmer encounter rate with oil, operator skill, visibility, temperature, and weather (Lees, 1993; Casey and Caplis, 2014).

potential in a defined scenario. The BSEE ERSP Calculator allowed users to determine the ERSP for recovery systems in an open-water environment. That calculator was reviewed by the National Research Council (the programmatic arm of the National Academies of Sciences, Engineering, and Medicine) in 2013 (NRC, 2013).

In the years since, there has been a recognition that the BSEE ERSP Calculator may not be applicable to inland and nearshore spills. Recognizing these potential limitations, the USCG contracted with RPS Group (RPS) to modify the BSEE ERSP Calculator for application to inland and nearshore systems. This initiative started because a group of stakeholders, including the USCG, wondered if the BSEE ERSP Calculator would be effective for planning in inland and nearshore environments. In 2017, the USCG hosted a workshop with subject-matter experts (including the USCG, Environmental Protection Agency, National Oceanic and Atmospheric Administration [NOAA], and Pipeline and Hazardous Materials Safety Administration, and various industry stakeholders) where it was agreed that challenges existed in attempting to apply the BSEE ERSP Calculator to spills in the inland environment. In 2018, the USCG Research and Development Center entered into a contract with RPS to develop a conceptual model based on a review of the literature, research, and interviews with subject-matter experts. This group (referred to as the “Project Team” in the sponsor-provided documentation) finalized a list of the features and factors that needed to be included in a new, Inland ERSP Prototype Calculator (USCG Inland ERSP Calculator); produced a conceptual model report that provided an overview of the calculator and described the relationship of all factors in worst-case, maximum most probable, and average most probable discharge scenarios (USCG, 2021b); produced a design document containing all algorithms needed for calculator function (USCG, 2021a); produced a quick-start guide serving as a user manual for the calculator tool; and produced a validation and verification document detailing the process for the development of the prototype calculator (USCG, 2021c). The resulting USCG Inland ERSP Calculator is the subject of the present review.

STUDY TASK AND APPROACH

This committee was asked by the U.S. Coast Guard (USCG) to review the Inland Estimated Recovery System Potential (ERSP) Prototype Calculator and associated quick-start guide for the software. The committee was to scientifically assess, and provide recommendations for improving, ERSP methodologies; to inform oil spill planning and preparedness for the inland and nearshore environments; and to provide recommendations for new ERSP methodologies and guidelines, if any, for mechanical response systems deployed in inland and nearshore operating environments (see Box 1.1).

Based on the documents provided by the sponsor (accessible in the National Academies public access file through the Public Access Records Office), the committee understands the prototype calculator as a potential USCG planning tool for evaluating a total system approach to on-water mechanical recovery in inland and nearshore environments. The calculator is intended to work in a manner similar to the BSEE ERSP Calculator, with modifications to the calculation methodology to include key characteristics of the inland and nearshore operating environments that influence the system’s recovery performance.

The committee struggled at times with the use of several terms throughout the work documents provided, their intended meaning, and their overall impact on the findings.

While the term “planning tool” was used to describe the calculator throughout the provided documents, the sponsor’s definition of that term was not always clear to the committee. When asked to further define the term with respect to the calculator’s intended use, the sponsor responded, “USCG is seeking to improve readiness to oil spills in environments that may not be feasibly addressed by the Offshore ERSP calculator. . . . This tool should be used well in advance of any spill, and is definitely not intended for tactical responses.” The term “planning” has broad meaning in the oil spill response industry and is most often used in conjunction with an action that is intended to meet a specific regulatory planning standard. During initial review of the supporting documents, as well as the sponsor’s answers to committee-generated questions, it was stated that the calculator was not intended to be used for this purpose. Without a clear understanding of how the tool is intended to be used, it was difficult to establish criteria for overall appropriateness.

The term “methodology” was used in three of the four enumerated tasks within the statement of task. The committee found this term to have several possible meanings, based on review of previous studies conducted in the evolution of EDRC to ERSP. There was some confusion as to whether the intent was for the committee to review and provide feedback on the USCG Inland ERSP Calculator methodologies (i.e., inputs and algorithms), the methods used for developing the calculator concept, or both. The sponsor was not asked to clarify what was meant by this term. Instead, for this review, the committee interprets the term “methodology” to refer to both the concept development as well as the inputs and algorithms in the prototype calculator.

The terms “nearshore” and “inland” are also used throughout the sponsor-provided documents and contributed to some confusion on the committee’s part as they have very specific meanings from a regulatory standpoint and define operating areas used in establishing mechanical classification standards under the OSRO Classification system (USCG, 2019). The sponsor indicated to the committee that use of the terms “inland” and “nearshore” for this project should be considered generic and not tied to any existing regulatory definition. The committee is concerned that the use of these terms in a generic manner may lead to confusion or misrepresentation amongst plan holders, planners, and OSROs. For that reason, the committee elected to use the term “inland” in the present report and considered the term “nearshore” to generically refer to areas immediately adjacent to a shoreline, thus a subset of inland environments. This is the case for all instances except when referencing the statement of task and events that took place outside of the committee’s work.

The committee understands the statement of task (Box 1.1) to consist of two parts. The first, as listed in items 1 and 2 of the statement of task, is an assessment of the prototype calculator to determine the ERSP of a mechanical skimming system when deployed in inland and nearshore environments. Part of this assessment is the inclusion of an explanation of the criteria used in the evaluation and justification for the committee’s disposition on the appropriateness determination. The committee considered appropriateness in two ways: (1) the calculation (e.g., inputs, algorithms, and outputs) and (2) the calculator’s use in spill response planning (e.g., inputs and outputs). The second part of the statement of task, included in items 3 and 4, seeks the committee’s recommendations for improving current USCG Inland ERSP Calculator methodologies and recommendations for new USCG Inland ERSP Calculator methodologies and guidelines. The committee considers the request for improving methodologies to be their suggestions for modifications to the calculator inputs, algorithms, and outputs as presented. The committee considers the request for new methodologies to be their suggestions beyond ERSP calculators for mechanical recovery system planning in the inland and nearshore environments.

The committee’s deliberations and review were focused on the calculator’s capabilities, review of appropriate standards and literature, and information provided during a series of public meetings and presentations, drawing on expertise from academic, governmental, and nongovernmental communities.

The committee was provided seven files relating to the USCG Inland ERSP Calculator:

1. Recorded presentation about the Inland ERSP Calculator that USCG presented at the International Oil Spill Conference in 2021;
2. Conceptual Model Report;
3. Design Document;
4. Quick-Start Guide;
5. Verification and Validation Document;
6. Calculator software; and
7. Calculator source code.

To support information-gathering efforts, the committee held four virtual, public meetings where experts from federal and local governments, industry, and academia were invited to talk to the committee. During these meetings the committee discussed the statement of task, considered the calculator design, prototype, and user guide, and resolved outstanding questions. Other topics of discussion included oil spill response, oil behavior, and practical considerations in inland oil spill response. The committee sought meeting participation from the team that designed, implemented, and validated the model, including Coast Guard Marine Environmental Response (CG-MER) and RPS Group. However, CG-MER preferred to respond to the committee’s inquiries by e-mail, through the sponsor, and RPS’s participation with the committee was outside of their related task order agreement with the USCG. During their information-gathering sessions, the committee heard perspectives from the American Society for Testing and Materials F-20 Committee on Hazardous Substances and Oil Spill Response and NOAA’s Office of Response and Restoration.

Following review of the shared documentation and the first open-session meeting, the committee developed and submitted a list of questions for clarification and explanation of the calculator’s use and capabilities directly to USCG. These questions, and subsequent responses prepared by USCG Research and Development Center (accessible in the National Academies public access file through the Public Access Records Office), were circulated among the CG-MER team for consideration. Central to the committee’s proposed assessment of the USCG Inland ERSP Calculator was a greater understanding of its intended purpose. Although it had been stated in the USCG-provided documentation that the calculator was to be utilized as a “planning tool,” the committee asked a number of specific questions designed to further identify the meaning and intent. For example, the committee was interested in the potential (or intended) use of the calculator in establishing regulatory compliance matters. Unfortunately, CG-MER indicated that they preferred not to comment on the regulation or policy aspect of the calculator until after the present National Academies report has been released. While all responses received a cursory review from the RPS portion of the Project Team, and RPS added responses to select questions, it was outside the scope of the current RPS and USCG task order to participate in the information-gathering component of the present study. Thus, despite requests, the committee was unable to meet directly with anyone from RPS, or their team of subcontractors. Generally, all Project Team respondents were in agreement and RPS noted that they would be able to provide more in-depth answers to questions and concerns regarding the prototype calculator in a white paper response to the present report.

Note that this report is a review of the prototype calculator, and the assessment is based on the calculator and its documentation “as presented.”

The present report is organized to generally align with the statement of task. Chapter 2 of this report highlights key distinctions between the inland and offshore environments that impact both oil behavior and fate, and response operations. It is important to understand these distinctions when considering inputs into the calculator and, ultimately, its applicability. Chapter 2 also describes a continuum of complexity that

extends from regulatory planning to predictive modeling. Finally, Chapter 2 outlines criteria that the committee considered in its evaluation of the calculator’s appropriateness and provides the committee’s high-level determination. Chapter 3 provides a more in-depth discussion of how the calculator works, including consideration of the inputs, outputs, algorithms, mechanics, and interface. Chapter 4 provides committee findings and recommendations regarding methodological improvements aimed at enhancing the current calculator’s use as a planning tool and new ERSP methodologies and guidelines.