IEEE Std 980-2021: Oil Spill Containment Guide for Substations

IEEE Power and Energy Society STANDARDS IEEE Guide for Containment and Control of Oil Spills in Substations Developed by the Substations Committee IEEE Std 980™-2021 (Revision of IEEE Std 980-2013) Authorized licensed use limited to: Universidad Industrial de Santander. Downloaded on March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980™-2021 (Revision of IEEE Std 980-2013) IEEE Guide for Containment and Control of Oil Spills in Substations Developed by the Substations Committee of the IEEE Power and Energy Society Approved 8 December 2021 IEEE SA Standards Board Authorized licensed use limited to: Universidad Industrial de Santander. Downloaded on March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. Abstract: The significance of oil-spillage regulations and their applicability to electric substations are discussed; the sources of oil spills are identified; typical designs and methods for dealing with oil containment and control of oil spills are discussed; and guidelines for preparation of a typical Spill Prevention Control and Countermeasures (SPCC) plan are provided. This guide excludes polychlorinated biphenyl (PCB) handling and disposal considerations. Keywords: collecting pit, IEEE 980™, oil containment methods, oil containment system, oil discharge, oil spill, primary oil containment, retention pit, secondary oil containment, spill prevention control and countermeasures (SPCC) plan The Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue, New York, NY 10016-5997, USA Copyright © 2022 by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Published 20 April 2022. Printed in the United States of America. 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Participants At the time this IEEE guide was completed, the E2―Guide for Containment and Control of Oil Spills Working Group had the following membership: Mike McNulty, Chair Mihai Morea, Vice Chair Greg Ardrey Matthew Bauer Carolyn Baxter Geoffrey Biela Mike Brown Eric Chin Edward Crockett Jean-Bernard Dastous Bruce Dietzman Brian Farmer Roderick Giron Arthur Graves Dragana Hadziosmanovic Brian Herrmann Nicole Hunter Caleb Jurgenson Dan Koons Mark Lavanish Thomas McConnell Olivia Miller Francis Mills Joseph Moore Rick Nugent Shashikant Patel Thomas Proios Robert Ramsey Brian Schnurr Eric Schwiderson Arjun Shanmungen Mark Smedvig Brian Story Sadie Thompson Rustyn VanDeventer Dustin Weaver Stuart Williams The following members of the individual Standards Association balloting group voted on this recommended practice. Balloters may have voted for approval, disapproval, or abstention. Richard Anderson Thomas Barnes Matthew Bauer W.J.(Bill) Bergman Steven Bezner Wallace Binder William Byrd Michael Chirico Randy Clelland Michael Dood Thomas Dunmore II Donald Dunn Jalal Gohari Edwin Goodwin Paul Guidry Steve Hamilton Werner Hoelzl Robert Hoerauf Richard Jackson Laszlo Kadar John Kay Thomas Keels James Kinney Boris Kogan Chung-Yiu Lam Otto Lynch Jeffrey McElray Daleep Mohla Jerry Murphy Paul Myers Dennis Neitzel Arthur Neubauer Joe Nims Rick Nugent Sivaraman P Lorraine Padden Bansi Patel Shashikant Patel Christopher Petrola Branimir Petosic Patty Polpattana Moises Ramos Ryandi Ryandi Bartien Sayogo Devki Sharma Hyeong Sim Jerry Smith Gary Smullin Kris Sommerstad Joseph Sowell Ralph Stell Brian Story Paul Sullivan Wayne Timm Matthew Vacha John Vergis Jane Verner Donald Wengerter Kenneth White Kris Zibert When the IEEE SA Standards Board approved this recommended practice on 8 December 2021, it had the following membership: Gary Hoffman, Chair Jon Walter Rosdahl, Vice Chair John D. Kulick, Past Chair Konstantinos Karachalios, Secretary Edward A. Addy Doug Edwards Ramy Ahmed Fathy J.Travis Griffith Thomas Koshy Joseph L. Koepfinger* 7 David J. Law Howard Li Daozhuang Lin © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. Kevin Lu Daleep C. Mohla Chenhui Niu Damir Novosel Annette Reilly Dorothy Stanley Mehmet Ulema Lei Wang F.Keith Waters Karl Weber Sha Wei Howard Wolfman Daidi Zhong *Member Emeritus 8 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. Introduction This introduction is not part of IEEE Std 980-2021, IEEE Guide for Containment and Control of Oil Spills in Substations. Many international governments, on federal or local levels, have implemented regulations prohibiting the discharge of oil into waterways and the environment. Often these regulations require the preparation of spill prevention and response plans for certain facilities, including electrical substations. It is prudent to recognize that a potential for oil spills exists in almost every substation throughout the utility industry. It is consequently reasonable to identify the extent of the problem, if any, and to recommend plausible measures to control oil spills by means of an IEEE guide. This guide was revised by members of Working Group E2—Guide for Containment and Control of Oil Spills (IEEE Std 980)—and is under the sponsorship of the Transmission and Distribution Substations Operations Subcommittee of the IEEE Power and Energy Society (PES) Substations Committee. This revision includes metrication, a deemphasis on US regulations, containment comparison tables, and inclusion of updated design figures and photos. Additionally, significant historical survey data were removed from the text and relocated to the annex. 9 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. Contents 1. Overview�� 14 1.1 Scope�� 14 1.2 Purpose�� 14 1.3 Word usage�� 14 2. Normative references�� 15 3. Definitions�� 15 4. Statutory requirements�� 16 5. Oil spill sources�� 17 5.1 Oil-filled equipment�� 17 5.2 Cables�� 18 5.3 Mobile equipment�� 19 5.4 Oil-handling equipment�� 19 5.5 Oil storage tanks�� 20 5.6 Other sources�� 20 6. Criteria�� 21 6.1 Probability of oil spills�� 22 6.2 Application determination�� 23 6.3 Performance monitoring�� 23 7. Containment�� 24 7.1 Containment systems�� 25 7.2 Storm-water management and control�� 46 7.3 Warning alarms and monitoring�� 60 7.4 Maintenance of oil containment systems�� 61 8. Control and response�� 62 8.1 Typical spill response plan requirements�� 62 8.2 Control and cleanup in substations�� 65 8.3 Disposal�� 66 8.4 Maintenance of equipment�� 66 Annex A (informative) Typical information included in notification form and spill report8�� 67 Annex B (informative) Collecting pit volume calculation�� 69 Annex C (informative) Summary of past IEEE oil containment surveys�� 71 Annex D (informative) Bibliography�� 79 10 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. List of Figures Figure 1—Oil-filled 345 kV power transformer�� 18 Figure 2—120 kV oil circuit breaker�� 18 Figure 3—Ruptured transformer and resultant oil spill�� 18 Figure 4—Oil-filled cable pumping facilities�� 19 Figure 5—Cable terminations (potheads)�� 19 Figure 6—Containment for a mobile generator�� 19 Figure 7—Containment for tanker of transformer oil in the process of filling a transformer�� 20 Figure 8—Oil/fuel storage tank�� 20 Figure 9—Capacitors containing dielectric oil in storage�� 21 Figure 10—Oil/fuel storage containers�� 21 Figure 11—Typical stone used for the stone mat and in stone-filled containment�� 26 Figure 12—Installation of in-ground synthetic liner�� 27 Figure 13—Installation of in-ground synthetic liner�� 27 Figure 14—Installation of an impervious synthetic liner�� 27 Figure 15—Spray-in liner installation utilizing cinder block walls�� 28 Figure 16—Substation stone mat with perimeter stone berm�� 36 Figure 17—Typical oil containment system with retention pit�� 37 Figure 18—Typical oil containment system where the entire substation drains to a retention pond that has an oil/water separator (inverted pipe) outlet�� 37 Figure 19—Cross section of oil containment system with retention pit�� 38 Figure 20—Typical oil containment system with discharge control system�� 38 Figure 21—Typical oil containment system with a discharge control system with a stone-filled pit and aboveground fiberglass dike that drains through a polymer bead filter�� 39 Figure 22—Typical concrete pit�� 40 Figure 23—Subsurface concrete containment pit with concrete wall under construction�� 41 Figure 24—At-grade concrete containment with wall/dike�� 41 Figure 25—Concrete containment pit with access grating�� 41 Figure 26—Typical earthen pit with impervious liner�� 41 Figure 27—Earthen containment pit with impervious liner being installed�� 42 Figure 28—Stone-mat containment with fiberglass dike�� 42 11 © 2022 IEEE. 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Figure 29—Earthen containments with earthen berms all with stone-mat cover�� 42 Figure 30—Portable containment for temporary/spare equipment�� 42 Figure 31—Typical oil containment system with earth dike�� 43 Figure 32—Typical portable berms and tanks�� 44 Figure 33—Fiber/geotextile berm containing “windows” of polymer beads�� 45 Figure 34—Cross-section of fiber/geotextile berm showing layer of polymer beads�� 45 Figure 35—Sump pump that pumps accumulated liquids through an in-line polymer bead filter�� 45 Figure 36—End-of-pipe polymer-filled filters attached to a header system where high storm-water flows are expected�� 46 Figure 37—In-line oil-absorbing polymer bead filter ready for installation�� 46 Figure 38—Oil–water gravity separator (for warm climates)�� 47 Figure 39—Simple inverted outlet, oil-water, gravity separator�� 52 Figure 40—Oil–water gravity separator (for cold climates)�� 52 Figure 41—Oil–water separator at the oil retention pit�� 53 Figure 42—Simple oil–water separator�� 53 Figure 43——Oil-trap-type oil–water separator�� 54 Figure 44—Oil-absorbing polymer bead bed (installed in manhole)�� 55 Figure 45—Imbiber valve concrete structure with valve removed showing concrete structure and outlet pipe�� 56 Figure 46—Oil-absorbing polymer bead bed (installed in drain pipe)�� 56 Figure 47—Oil stop valve�� 57 Figure 48—Specific gravity type oil stop valve ready for installation�� 57 Figure 49—Oil stop valve being installed in a manhole�� 57 Figure 50—Sump pump water discharge (with oil-sensing probe)�� 59 Figure 51—Oil-sensing pump system�� 60 Figure 52—Mud valve�� 60 Figure 53—Polymer bead filter fitted on end of manual valve�� 60 Figure B.1—Oil collecting pit�� 70 12 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. List of Tables Table 1—Common secondary oil containment evaluation criteria�� 22 Table 2—Common equipment for which secondary containment is provided�� 22 Table 3—Containment method utilization�� 24 Table 4—Soil permeability characteristics�� 26 Table 5—Common containment pit liners�� 28 Table 6—IEEE comparison of containment systems�� 31 Table 7—Comparison of environmental storm-water control systems�� 48 Table C.1—Secondary oil containment evaluation criteria�� 71 Table C.2—Secondary oil containment equipment criteria�� 71 Table C.3—Containment method utilization�� 72 Table C.4—Containment pit liners�� 73 13 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Guide for Containment and Control of Oil Spills in Substations 1. Overview 1.1 Scope This guide discusses the significance of oil spillage in electric substations; identifies the sources of oil spills; discusses typical designs and methods for dealing with oil containment and control of oil spills; and provides guidelines for preparation of a typical spill prevention control and mitigation plan. This guide applies to all types of insulating oil, fuel, and other oils typical of electrical substations. It is not the intent of this guide to interpret government regulations or the applicability of the oil containment systems presented with respect to compliance to those regulations. Interpretation is left to each individual user. Note that much of the material and information in this guide is based on discussions, experiences, and research conducted by the IEEE Oil Containment Working Group. Part of this research includes industry surveys conducted in 1992 and 2012 in an effort to determine common practices for oil containment and control in electrical substations. Although generally not discussed in the body of this guide, the detailed survey results can be found within Annex C. 1.2 Purpose Containment, control, and mitigation of oil spills are a concern for owners and operators of electric substations. The environmental impact of oil spills and their mitigation is regulated by some governmental agencies, necessitating increased attention in substations to the need for secondary oil containment. Beyond the threat to the environment, mitigation costs associated with oil spills continue to escalate and the adverse community response to any spill is becoming increasingly unacceptable. This guide identifies some governmental regulations, the sources of oil spills, and typical methods and plans used to contain, control, and mitigate them. Note that use of the term “oil” in this document includes mineral oil and other alternative insulating fluids. 1.3 Word usage The word shall indicates mandatory requirements strictly to be followed in order to conform to the standard and from which no deviation is permitted (shall equals is required to).1,2 1 The use of the word must is deprecated and cannot be used when stating mandatory requirements, must is used only to describe unavoidable situations. 2 The use of will is deprecated and cannot be used when stating mandatory requirements, will is only used in statements of fact. 14 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations The word should indicates that among several possibilities one is recommended as particularly suitable, without mentioning or excluding others; or that a certain course of action is preferred but not necessarily required (should equals is recommended that). The word may is used to indicate a course of action permissible within the limits of the standard (may equals is permitted to). The word can is used for statements of possibility and capability, whether material, physical, or causal (can equals is able to). 2. Normative references The following referenced documents are indispensable for the application of this document (i.e., they must be understood and used, so each referenced document is cited in text and its relationship to this document is explained). For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies. U.S. Code of Federal Regulations, Title 40 (40 CFR), Protection of Environment, Parts 110 and 112.3 3. Definitions For the purposes of this document, the following terms and definitions apply. The IEEE Standards Dictionary Online should be consulted for terms not defined in this clause.4 alternative insulating fluid: Any dielectric fluid of low relative permittivity, such as synthetic or natural esters, that may be used to insulate electrical current in transformers and other equipment in lieu of a refined high-alkane petroleum product such as mineral oil. collecting pit: A pit built under oil-filled equipment to collect any accidental discharge of oil from that piece of equipment. dewatering: To remove water from. gallon: One US gallon (gal); equivalent to 3.785 L. harmful quantity of oil: A legal term of art defined by US regulation (40 CFR, Part 110), and it is defined to be a discharge of oil that (1) violates applicable water quality standards, (2) causes a film or sheen upon or discoloration of the surface of the water or adjoining shorelines, or (3) causes a sludge or emulsion to be deposited beneath the surface of the water or upon adjoining shorelines. impervious liner: Any lining comprising woven or nonwoven synthetic fabric, compacted natural clay soils, or a man-made cementitious mixture that prohibits the flow of fluid from one side of the barrier to the other. oil: Any of numerous mineral, synthetic, or biological lipid substances that are generally slippery, combustible, viscous, liquid or liquefiable at room temperatures, hydrophobic, and used in a great variety of products, especially as lubricants, fuels, and electrical insulation media. oil containment system: A system designed to collect and retain oil in order to prevent (1) its migration beyond the boundaries of the system and (2) the contamination of the environment. CFR publications are available from the U.S. Government Printing Office (https://www.gpo.gov/). IEEE Standards Dictionary Online is available at: http://dictionary.ieee.org. An IEEE account is required for access to the dictionary, and one can be created at no charge on the dictionary sign-in page. 3 4 15 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations oil spill: Any leak or spillage of oil, regardless of volume and including those that do not reach navigable waters. A spill includes but is not limited to any discharge, leaking, pumping, pouring, emitting, emptying, or dumping of oil. permeability: The drainage characteristic of a porous material that denotes its capacity to conduct or discharge fluids under a given hydraulic gradient. primary oil containment: A tank or enclosure designed for continuous containment of oil for operating or storage purposes. retention pit: A pit designed to retain (hold) oil-contaminated liquids. secondary oil containment: A system designed to contain the oil discharged from an oil-filled piece of equipment in situations of primary oil containment failure. porosity: The volume of the void space in a porous material divided by the total volume occupied by the porous material. 4. Statutory requirements Many countries and local units of government have generally adopted regulations prohibiting discharges of oil into the environment, with an increased focus on waterways. These regulations may be more encompassing and restrictive than the US federal regulations referenced in this document. The applicability and requirements for spill prevention and containment plans in foreign countries and local government jurisdictions vary and are not discussed in detail within this guide. It is the responsibility of the reader to investigate and determine the applicable regulatory statutes and requirements within his or her own governmental jurisdiction. The US federal requirements for discharge, control, and countermeasure plans for oil spills are contained in the Code of Federal Regulations, Title 40 (40 CFR), Parts 110 and 112.5 The purpose of these regulations is to prevent the discharge of oil in harmful quantities into navigable waters, which also includes shorelines, wetlands, or areas that would adversely affect the natural resources of the US, and to provide for containment systems in lieu of only providing cleanup measures after a spill has occurred. Definitions and specifics regarding navigable waters and other terms that are covered by these regulations are contained in the publication. The regulations are very dynamic and have been amended many times since their inception and may have changed since the publication of this guide. The user is cautioned to check the latest regulations for revisions. The application of these federal regulations to oil-spill containment and control in substations is governed by several key points that have been subject to revision or interpretation. These include the following: 5 a) Appropriate containment is required if volumes exceed the minimum storage capacity in a single container or the entire substation, at which level a Spill Prevention Control and Countermeasures (SPCC) plan is also required. Any change from the current limits may significantly impact the number of transformers, circuit breakers, and other oil-filled substation equipment where secondary containment is required. At the time of this publication, the current criteria are aggregated above ground oil storage capacity greater than 4997 L (1320 gal) or completely buried oil storage capacity greater than 158 987 L (42 000 gal). Containers with a storage capacity equal to or less than 208 L (55 gal) of oil are not included in the calculation of the total aggregated capacity. b) Regulations listed in 40 CFR, Part 112, currently require secondary oil containment for what can be considered a “bulk storage tank.” The proposed rules currently indicate that transformers and other electrical equipment containing oil for operational rather than storage purposes will not be considered “bulk storage tanks.” Information on references can be found in Clause 2. 16 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations c) The term “navigable waters”, as currently written in 40 CFR, Part 110, is broad and encompassing. As defined by the US. Environmental Protection Agency (EPA), it can include, in addition to the major lakes and waterways, tributaries of rivers, lakes, and streams, as well as mud flats and wetlands. d) The amount of discharged oil that constitutes harmful quantities. Interpretation of the specific regulations is left to each individual user. These regulations prohibit the discharge of oil in harmful quantities into navigable waters of the United States. Through the implementation of an SPCC plan, which may include secondary containment, the regulations require that effective containment plans be made to prevent the discharge of oil and specify that a cleanup procedure or contingency plan be established to be implemented in the event of an oil spill. A contingency plan alone can be utilized only where containment is shown to be impractical. Oil containment may be deemed impractical in situations where constraints prevent the installation of oil containment systems and/or it is highly unlikely that oil would reach and contaminate navigable waters in the event of a discharge. Financial considerations alone are not a valid argument for not providing oil containment, as any contamination of navigable waters is unacceptable. Also, the cost associated with the expeditious cleanup of a spill could exceed the cost of providing secondary oil containment. Guidance and requirements for reporting oil spills to the EPA are also incorporated in the regulations prohibiting the discharge of harmful quantities of oil under 40 CFR, Part 112. EPA regulations require that each qualifying facility has a site-specific plan. Sufficient detail shall be included in the overall plan to identify location of equipment, quantity of oil, grade and slope of the site and surrounding area, and area drainage patterns. In summary, federal regulations require that each installation exceeding the specified storage capacity limitations be assessed for the possibility of contaminating navigable waters. If the potential for contamination exists, then an SPCC plan (see 8.1) shall be developed. Such a plan shall contain all requirements of 40 CFR, Part 112.7, including appropriate containment provisions and a countermeasures cleanup plan. The above synopsis provides a brief regulatory overview of US federal regulations relating to oil containment in electrical substations. This is intended to provide a framework or background as to the need for oil spill control and mitigation measures at substations. Several other nations, and even local or state units of government, may also have similar regulations. Each user of this guide is encouraged to investigate the regulatory applicability of their respective operations. Many utilities and operators of electrical substations employ oil spill control measures as an act of corporate citizenship and environmental stewardship beyond just a regulatory obligation. These can also be motivating factors and criteria for consideration when evaluating the need for oil containment. 5. Oil spill sources Within this clause are descriptions of various sources of oil spills within substations. Spills from any of these sources are possible. The user should evaluate the quantity of oil present, the potential impact of a spill, and the need for oil containment associated with each source of oil. Spills may be caused by electrical failure, leaks, vandalism, sabotage, or accident. 5.1 Oil-filled equipment Power transformers, reactors, regulators, and circuit breakers are common potential sources of both major and minor oil spills in substations as shown in Figure 1, through Figure 3 since they typically contain large quantities of oil. 17 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 1—Oil-filled 345 kV power transformer Figure 2—120 kV oil circuit breaker Figure 3—Ruptured transformer and resultant oil spill 5.2 Cables Substation pumping facilities shown in Figure 4 and cable terminations (potheads) that maintain oil pressure in pipe-type cable installations shown in Figure 5 can be a source of oil spills. 18 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 4—Oil-filled cable pumping facilities Figure 5—Cable terminations (potheads) 5.3 Mobile equipment Although mobile equipment and emergency facilities containing oil, such as portable substations and emergency generators, as shown in Figure 6 may be used infrequently, consideration should be given to the quantity of oil contained and associated risk of oil spill. Figure 6—Containment for a mobile generator 5.4 Oil-handling equipment Oil is filled into equipment at completion of initial installation. The filling of a transformer with oil is shown in Figure 7. In addition, periodic reprocessing or replacement of the oil may be necessary to maintain the proper insulation qualities of the oil. Oil pumps, temporary storage facilities, hoses, and so on, are brought in to accomplish this task. Spills from these activities can occur. 19 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 7—Containment for tanker of transformer oil in the process of filling a transformer 5.5 Oil storage tanks Consideration should be given to the presence of bulk oil storage tanks as shown in Figure 8 (either above or below ground) in substations. The applicability of certain local or federal regulations, such as the 40 CFR, Part 112, for those storage tanks could require increased secondary oil containment for the entire substation facility. Figure 8—Oil/fuel storage tank 5.6 Other sources Station service, voltage, and current transformers, oil circuit reclosers, capacitor banks, and other pieces of electrical equipment typically found in substations may contain small amounts of insulating oil as shown in Figure 9 and Figure 10. Although they may contain less oil than qualifying thresholds stated within certain regulations, they may be considered to be sources of oil. 20 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 9—Capacitors containing dielectric oil in storage Figure 10—Oil/fuel storage containers 6. Criteria Based on the applicability of the latest regulatory requirements, or when unacceptable risk factors have been identified, a program may be put in place to mitigate the risk of a spill to the environment. Typical criteria for implementing oil spill containment and control programs include equipment type and oil volume, potential environmental impact, severity of potential damage, adjacent natural features, regulatory requirements, corporate policy, frequency and duration of occurrences, cost of occurrences, safety hazards, substation location, and quality of service requirements. The decision to install secondary containment at new substations (or to retrofit existing substations) is usually based on predetermined criteria. Based on industry feedback, historical IEEE surveys (Annex C) and the research conducted by the IEEE Oil Containment Working Group, the criteria in Table 1 are commonly considered when evaluating the need for secondary oil containment. Rarely is all of the equipment within a given substation provided with secondary containment. Table 2 identifies equipment for which secondary oil containment is commonly provided. The greatest focus is on equipment that contains the largest quantities of oil. 21 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Table 1—Common secondary oil containment evaluation criteria Criteria Volume of oil in individual device Proximity to navigable waters Total volume of oil in substation Potential contamination of groundwater Soil characteristics of the station Location of substation (urban, rural, remote) Emergency response time if a spill occurs Failure probability of the equipment Age of station or equipment Table 2—Common equipment for which secondary containment is provided Equipment Power transformers Aboveground oil storage tanks Station service transformers Oil circuit breakers Three-phase regulators Below-ground oil storage tanks Shunt reactors Oil-filling equipment Oil-filled cable reservoirs/pumping stations Single-phase regulators Oil circuit reclosers Other criteria not captured in Table 1 but considered common in industry practice include (1) modeling software to determine the potential for oil spills to migrate off-site and into surface water and (2) the individual piece of electrical equipment being equipped with supervisory control and data acquisition (SCADA) monitoring capabilities. Each substation should be evaluated by considering appropriate criteria to determine the need for oil containment systems (both new and retrofit). Use of electrical criteria (e.g., phase-to-phase voltage) is discouraged because nonelectrical characteristics (e.g., oil volumes) are more important when judging the risks of oil spills. Substations with planned equipment replacements may be considered for retrofits at the time of the change out. 6.1 Probability of oil spills The frequency of oil spills in substations reaching navigable waters or adjoining shorelines can be considered low based on historical survey results. The probability of an oil spill at any particular location depends on the number of oil sources and their volume in addition to other site-specific conditions. The probability of a spill was surveyed by two questionnaires submitted in 1977 to utility members of the IEEE Substations Committee by the Oil Spill Prevention, Control, and Countermeasures Task Force of the Environmental Subcommittee. 22 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations The information gathered from responding utilities showed that during the 10-year period from 1965 to 1974, responding utilities had less than one discharge per 330 pieces of in-service, oil-containing equipment. For the same period, reaching a waterway was even less likely, with less than one discharge reaching a navigable waterway for each 5275 pieces of in-service, oil-containing equipment. Over the two-year period from 1975 to 1976, responding utilities had less than one discharge for each 1200 pieces of equipment in service. For the same two year period, less than one discharge for every 6640 pieces of in-service, oil-containing equipment reached a navigable waterway. A survey conducted in 2012 by the IEEE Oil Containment Working Group, along with evidence gathered during Working Group meetings, showed similar results. While it can be concluded that an oil discharge actually reaching a navigable waterway or adjoining shorelines could be considered rare, the results also indicated that is not uncommon for more minor oil spills and discharges to occur within substations. Note that this could also be the result of oil containment being more of a common practice in substation design and planning within the utility industry, thus lowering the probability of an oil spill reaching a waterway. The task force concluded that while available empirical data was not precise, it indicated that the probability of spills per piece of equipment in service per year is low. Computer-based modeling software is available to assess the probability of oil migrating off-site and reaching navigable water. Such tools can be useful for determining a specific oil containment strategy for a substation. 6.2 Application determination After determining the requirement for oil containment, the design process may include a cost analysis, operations and maintenance considerations, review of applicable governmental regulations, and consideration of community acceptance. 6.2.1 Economic aspects Economic aspects can be studied when determining which containment system or control method to employ. The initial installation cost, as well as the operating and maintenance cost associated with the containment method, may be considered. Factors such as proximity to waterways, volume of oil, and utility response time following a spill may allow for the use of alternative methods at some locations. 6.2.2 Governmental regulations Due to the changing nature of environmental laws, some methods described in this guide may conflict with governmental regulations or overlapping jurisdictions after publication. Therefore, determination of which containment system or control method to use should always include research into and confirmation of current applicable laws and regulations. 6.2.3 Community acceptance Community acceptance of the oil spill containment and control methods may also be considered. Certain levels of unacceptability are intangible and may be dictated by company policies, community acceptance, and customer relations. Additional information on this topic can be found in IEEE Std 1127™ [B8].6 6.3 Performance monitoring Some means should be put in place for evaluating the effectiveness of any containment and control measures that have been applied. Records should be kept for each substation to record the method used, date of 6 The numbers in brackets correspond to those of the bibliography in Annex D. 23 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations application, and the history of oil spills. A record assists monitoring the performance of applied methods to evaluate the feasibility of future applications. Selection and type of record keeping should be determined by the individual owner/operator. Performance testing of secondary containment may be modeled after existing testing procedures, such as ACI 350.1 [B2] for concrete containment structures and Chapter VI and Chapter VII-Part 10 of ASME B31.3 [B3] for pipes. 7. Containment Many systems and strategies can be used to provide secondary containment for oil-containing electrical equipment at substations. The containment systems and strategies can prevent or mitigate the environmental impacts of a release or spill. These impacts can range from increased operating costs due to the cleanup and mitigation involved to contamination of private/regional domestic water sources and fish and/or wildlife mortalities. As there are many approaches to providing secondary containment, each site should be evaluated based on potential environmental impacts in the vicinity of the site, soil characteristics, topography, response time, and the type of equipment containing the material. In some cases, providing containment for individual pieces of equipment might be the best approach, whereas in other cases providing a single site-wide solution or drainage control might better fit the aspects of the site. Economics and constructability are also integral factors when considering secondary containment, especially for retrofit installations. There is no universal solution for secondary containment or containment dewatering, and each site should be evaluated for sitespecific solutions. It is beyond the scope of this guide to make specific recommendations as to which type of oil containment system is best suited for specific instances due to the wide range of site variables that can exist. However, as an aid to those engaged in the design of oil containment systems, this clause provides information on factors that may be considered in the design of containment and containment dewatering systems and gives examples of various types that have been used in the industry. Based on industry feedback, historical survey results (Annex C), and the research conducted by the IEEE Oil Containment Working Group, no single containment system or discharge control method is preferable or fits all situations. However, all methods listed in Table 3 have been used successfully. All users need to determine which method applies best to their containment need and site conditions. Constructability, installation restrictions, future maintenance requirements, and cost all need to be considered by each user. The US. Department of Agriculture, Rural Development Utilities Programs, Bulletin 1724E-302 [B14], provides additional information on oil containment methods in substations. Table 3—Containment method utilization Containment system or discharge control method Figure reference Perimeter or equipment berm Figure 31 and Figure 32 Fire-quenching and oil-retention pit Figure 22, Figure 26, and Figure 41 Oil-retention pit Figure 17 and Figure 19 Oil–water separator Figure 46 Oil-detection-triggered sump pump Figure 50 and Figure 51 Gravity separator Figure 38 and Figure 40 Oil–water stop valve Figure 47 Oil trap Figure 43 Oil-absorbing polymer bead bed Figure 44, Figure 45, and Figure 46 24 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations 7.1 Containment systems 7.1.1 Design considerations 7.1.1.1 Environmental concerns For new substations, the potential for environmental impact should be considered during the planning phase. If feasible, attempts should be made to avoid locating substations at sites that are near environmentally sensitive areas. Sensitive areas include those with high groundwater tables or those near wetlands, lakes, drains or rivers. Sites with known high groundwater levels are often more susceptible to flooding and would likely require an underdrain or storm sewer system. Spills at these sites could be quickly flushed off-site through groundwater flows toward bodies of water. Similarly, spills at sites adjacent to wetlands and bodies of water have the potential for significant environmental impact through surface runoff. Environmental cleanup of spills in sensitive areas are often costly and could have the potential to damage public relations and perception. For sites that are in or near sensitive environmental features, it is critical that containment be designed with the control and protection of groundwater and storm water as a focus. 7.1.1.2 Volume and dimensional requirements Before a substation oil containment system can be designed, the volume of oil to be contained should be known. Since the probability of a significant oil spill occurring at a substation could be considered low, the probability of simultaneous significant spills could be considered very low. In general, an oil containment system should be sized to contain the volume of oil in the single largest oilfilled piece of equipment, plus any accumulated water from sources such as rainwater, snowmelt, and possible fire protection system water spray discharge. Interconnecting two or more containment pools to share the design oil and water volume may provide the designer an opportunity to reduce the size requirements for each individual pit. Note, however, that interconnection may allow discharged oil to spread further and increase cleanup costs after an event. Expected rain and snow accumulations should be determined from local weather records. During design, a severe rainstorm is often considered to be the worst-case event when determining the maximum volume of short-term water accumulation. Although not specifically stated in the SPCC Rules, the US. EPA Inspector’s Guidelines recommend that the rainwater design criteria be based on a 25 year, 24 h storm event. The total volume of water from a storm event may be combined with the water available from a fire spray deluge system to determine the worst-case water volume to be used in a conservative containment system design. The designer may consider possible future upgrades resulting in a larger piece of equipment placed in service within the same containment. For collecting pits that are filled with stone, the stone size and porosity must be considered, as shown in Figure 11. Depending on the gradation uniformity of stone size used, porosity may vary from 20% to 50%. Furthermore, based on industry and Working Group member feedback, pits with small stones can restrict oil flow and become plugged by silt accumulation, indicating that larger stones may be more suited for oil containment areas. The need to use washed and uniformly sized stone is of fundamental importance. While it is possible to attain a porosity of 50%, a design figure of 35% is more feasible. See Annex B for an example of how to calculate the size of a collecting pit. The plan dimensions of the containment perimeter should consider the loss of oil through a variety of possible failure events. These include slow leaks and drips, piping/fitting failures, small holes/punctures (e.g., bullet holes), and large tank ruptures. Additionally, any oil pressure from operation or elevation head (the height of oil containing parts such as elevated conservator tanks) should be considered. 25 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Based on industry and Working Group member feedback, the planar distance from edge of oil containing part to the edge of the containment is typically the height of oil containing parts divided by 2 or simply 2 m to 3 m (6.6 ft to 9.8 ft). Figure 11—Typical stone used for the stone mat and in stone-filled containment 7.1.1.3 Soil characteristics and liners Soil is largely nonhomogeneous, possessing a wide range of physical properties. Of these properties, the soil’s drainage characteristic, or permeability, is the primary concern in the design of oil containment facilities. Permeability is a property of soil that denotes its capacity to conduct or discharge fluids under a given hydraulic gradient. It is measured as a flow rate in centimeters per second (cm/s). Coarse-grained soils are considered highly pervious and have corresponding high permeability coefficients, while fine-grained soils have low permeability coefficients. All conditions being equal, the higher the coefficient of permeability, the faster a fluid will drain through the soil. For the purposes of this guide, soils and their permeability characteristics have been adapted from typical references and can be generalized as in Table 4. Table 4—Soil permeability characteristics Permeability (cm/s) Degree of permeability Type of soil Over 10−1 High Stone, gravel, and coarse- to medium-grained sand 10 to 10 Medium Medium-grained sand to uniform, fine-grained sand 10−3 to 10−6 Low Uniform, fine-grained sand to silty sand or sandy clay Less than 10−6 Practically impermeable Silty sand or sandy clay to clay −1 −3 Consideration should be given to sealing or lining any collecting or retention pit to control horizontal and vertical migration of discharged oil into underlying soil layers. When native soil permeability alone is not adequate, installing a liner of low permeability such as a layer of clay, bentonite, or a plastic or poly-synthetic liner in the pit, as shown in Figure 12 through Figure 14, is a reasonable means of slowing oil movement and enhancing containment. Figure 15 shows spray-on materials such as polyurea and fiberglass that have also been used as a liner material. This type of liner bonds to concrete structures such as foundations and sumps and is easily molded to the topography of the containment area. 26 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 12—Installation of in-ground synthetic liner Figure 13—Installation of in-ground synthetic liner Figure 14—Installation of an impervious synthetic liner 27 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 15—Spray-in liner installation utilizing cinder block walls When a pit is lined, consideration should be given to the removal of accumulated water. Common methods for removal of precipitation from lined containment systems include manual removal through gate valves, use of pumps to manually remove the accumulated water, or relieving the water through a drainage pipe connected to devices such as oil–water separators or hydrocarbon filtering systems. Another popular method in the industry seems to be the use of liner systems that incorporate oil-absorbing polymers. These types of systems are attractive because they allow accumulated rainwater to escape passively. All of the liners in Table 5 have been applied with success. All these methods are discussed in more depth within 7.2. Many guides and codes exist that may advise the design of liners. For example, ACI 350 [B1] may be used for concrete lined pits, GRI-GCL5 [B5] may be used with geosynthetic clay liners, and ASME B31.3 [B3] may be used with pipes. Table 5—Common containment pit liners Liner type Concrete Synthetic Plastic (Polyethylene/Polypropylene) Synthetic Plastic with oil absorbing polymers Spray-In Polyurethane Bentonite/Clay Rubber 7.1.1.4 Fire-quenching considerations In places where the oil-filled device is installed in an open pit (not filled with stone), the possibility of a pool fire may be considered. If a major discharge occurs and the pooled oil in the pit catches on fire, the equipment will likely be destroyed. Some utilities alter their containment practices because of a pool fire possibility; however, many do not as they have decided that the risk was acceptable due to the low probability of the event. Those that do address this concern employ active or passive quenching systems or drain the oil to a remote pit. Active systems include foam or water spray deluge systems. Of the passive fire-quenching measures, pits filled with crushed stone are the most effective. The stonefilled pit provides a capability to extinguish flames by restricting available oxygen from the burning fluid in an equipment or oil pool fire event. Be advised that when designing and sizing a stone-filled collecting or retention pit, the final oil level elevation, assuming total oil discharge plus any additional design volume, should be situated approximately 150 mm (6 in) below the top elevation of the stone to suppress flames. The 28 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations use of a 38 mm (1.5 in) or larger diameter, clean washed, uniformly sized aggregate should be considered to permit quicker penetration by the oil to avoid a pool fire. The drainpipe material should be capable of withstanding the higher temperatures associated with an oil fire without melting. IEEE Std C57.12.00™ [B9] states that oil inside of transformers may be 65 °C (117 °F) hotter than the ambient temperature, and components of secondary containment that are exposed to oil should be able to withstand at least this temperature. If a pipe melts, the oil will be unable to drain away from the burning equipment, and the melted pipe may pose an environmental hazard. ASME B31.3 [B3] is a resource that lists temperature limits for different pipe materials. Refer to NFPA 850 [B11] and 8.2 in IEEE Std 979™ [B6] for additional information on fire protection considerations within substations. 7.1.1.5 Other considerations Spill response time and the availability of response equipment may also be considered when designing secondary containment. In remote areas where response time is greater, containment may need to be of greater volume and constructed of impervious materials. Additional attention may be given to the control and treatment of storm water at remote locations that are near environmentally sensitive areas. Similarly, oil-filled equipment that is near the substation fence line may be given additional consideration to prevent migration of spilled oil off-site. Secondary containment installed underground can affect grounding at a substation, and this should be considered when designing the grounding system. For retrofit situations, the designer will need to consider space and construction concerns, and the real risk of catastrophic loss in addition to the volume requirements, soils, and environmental concerns. In some cases, secondary containment for existing oil-filled circuit breakers may not be warranted due to the low potential risk of a catastrophic breaker failure. The SPCC Rule allows a deviation from the secondary containment rule for qualified oil-filled electrical equipment. The deviation requires that the owner prepare and implement an Oil Spill Contingency Plan according to 40 CFR, Part 112.20. Oil-filled breakers, transformers, and potential devices fall into the qualified oil-filled electrical equipment category, therefore the Oil Spill Contingency Plan may be used to comply with the SPCC Rule for these types of equipment. Where older installations pose a potential environmental hazard, it may be necessary to install containment around the existing equipment. Retrofitting can result in additional complications (and sometimes costs). Some of these are as follows: a) Power cable, control cable, conduit, grounding, and communication line relocations b) Equipment outages c) Equipment foundation repair d) Deep excavations that can undermine shallow equipment foundations e) Liner application around existing footings (special retrofit liners are available) f) Contaminated soil disposal g) Removal of bedrock h) Reduced vehicle mobility (during and after construction) To reduce the effect of these complications, it is advisable to consider a design that requires minimal excavation in proximity to the equipment. Shallow containment pits with piping to a common oil-retention pit or discharge 29 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations control system, the use of oil solidifiers or oil absorbent pads and booms (discussed in 7.1.2), and/or the use of area or site-wide berms may be the preferred method for retrofits. Equipment does not always need to be removed from the foundation to install this type of oil containment. If equipment foundation replacement is necessary to accommodate larger equipment, oil containment designs can be altered to take advantage of the opportunity for larger excavation, and any of the containment systems described in 7.1.2 can be utilized. Where excavation is impractical or too costly, an improvement in containment could be accomplished by the addition of berms around the existing equipment. Shallow installation of impervious liner and berms constructed of low permeability soil can be effective. 7.1.2 Examples of containment systems Table 6 provides a comparison of the containment systems typically used by the industry. The comments and comparisons in Table 6 are based on manufacturers’ specifications and on the experiences of the committee members. Table 6 provides information on the preferred application and the theory of operation of each system and covers considerations in choosing the best system for a particular situation. Following Table 6 is a more detailed description of the oil containment systems. All systems described are designed to fully contain discharged oil on site. These systems are generally installed without much difficulty while constructing new substations, but they may be impractical to install at existing substations. If constructing a complete oil containment system is impractical, a designer may consider use of other measures such as strategically located berms or dikes constructed of low-permeability soil and/or oil absorbents and solidifiers impeding and delay the flow of oil. This will provide extra time for cleanup operations. 7.1.2.1 Substation mat The surfacing material mat typically used in substations for base and grounding can, in conjunction with the overall grading of the site, contain the spread of released oil. A typical example is shown in Figure 16. The mats generally consist of a poorly graded (uniformly sized) and evenly distributed aggregate base with a depth varying from 7.6 cm (3 in) to 15.2 cm (6 in) deep across the substation. The mat alone can provide adequate secondary containment for equipment containing smaller volumes of dielectric oil. The units provided with containment should be located sufficiently far from the fence line to assure that any released materials are contained within the site and unable to follow any drainage pathways providing a route to off-site surface waters or municipal storm sewer systems. Sometimes impervious natural or synthetic liners are placed under the mat to prevent vertical migration of any released material. In addition, the mat may be evaluated after rainfall/snowmelt conditions where the possibility exists that the mat may be saturated, and any material released to the mat will float on top of the saturated mat and run off the site rather than traveling through the mat and being contained within the mat. Lastly, the response time of spill mitigation personnel should be sufficient to assure minimum spread within the mat in the event of a release. The stone mat can be used in conjunction with oil solidifiers and/or absorbents (further discussed in 7.1.2.4). Any amendments to the stone mat should be compared against electrical grounding considerations as specified in IEEE Std 80™ [B6]. 30 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. Substation mat Concrete pits, floors, dikes Compacted clay berms and liners Containment ponds Control type Spray-in polyurethane liner Table 6—IEEE comparison of containment systems Fiberglass composite panels Synthetic liner Table continues Geotextile barrier wall with layer/ windows of oleophilic polymer in conjunction with impervious geosynthetic liner IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. 31 Application The mats that are typically used in substations for base material and fire suppression should contain the spread of moderate amounts of released oil if the mat is maintained as designed. Concrete forms the floor and walls of the containment. Most often it is poured in a pit that has been excavated under the equipment. However, the floor can be atgrade with abovegrade walls. Pit can be covered with metal grate to provide access to the equipment. A few inches of stone can be placed on top of grate for fire suppression. Can be used as containment for single or multiple pieces of equipment. Often contains a collection sump that drains through an environmental control. The clay lines the bottom of the containment excavation and forms the berm wall. Typically, the compacted clay floor and berm are covered stone, ranging from a few inches to a few feet. These containments may have a sump that drains through an environmental control. Typically used to detain the drainage from multiple pieces of equipment or an entire substation and are equipped with an outlet structure that would prevent the escape of oil. Pond is typically lined with impervious synthetic liner or compacted clay. Control type Liner is sprayed into an excavation under and around the equipment. Often backfilled with stone. Uses fiberglass composite panels to form the walls of an aboveground containment system. Must be paired with an impervious liner of some type and an environmental control to drain the storm water. Often used in areas subject to flooding and/ or very high groundwater table. Commonly a few inches of stone are placed on the liner surface. Table 6—IEEE comparison of containment systems (continued) Placed in an excavation around/under oil filled equipment. The geosynthetic liner forms the bottom and sides of the containment. The liner is sealed to the foundation of the equipment. The excavation is backfilled with stone. The liner is generally used to contain single pieces of equipment and is typically paired with an environmental control to allow storm water to drain from the containment. © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. 32 Table continues Placed in an excavation around/under oil filled equipment. The barrier wall forms the outer sides of the containment. The geosynthetic liner forms the bottom and interior sides of the containment. The liner is sealed to the barrier wall and to the foundation of the equipment. The excavation is backfilled with stone. Typically used to contain single pieces of equipment. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Theory of operation The mat alone can provide adequate secondary containment for equipment that contains smaller volumes of dielectric oil and if the units that are being provided with the containment are sufficiently distant from the fence line and drainage structures that lead to off-site surface waters/ sewer systems to assure that any released materials are contained within the site. In some cases, impervious natural or synthetic liners are placed under the mat to prevent vertical migration of any released material. Concrete is relatively impervious to liquids and prevents the migration of oil out of the containment. If sized correctly the containment should contain any leak and some catastrophic losses. Although relatively impervious consideration should be given to sealing the concrete. The compacted clay is impervious and prevents liquids from migrating out of the containment. If sized correctly the containment should contain any leak and some catastrophic losses. Typically, the ponds outlet structure is designed so that the discharge is drawn from below the surface of the pond thus retaining any floating oils on the surface. Often the outlet is simply an inverted L shaped pipe or a weir. In some cases, the discharge from the pond drains through an environmental control. Control type The polyurethane liner is chemical resistant and impervious to liquids. Typically, a geotextile material is laid down first, then the spray liner is applied. The nature of the material itself and the application process allows for conformity to the ground surface, concrete foundations, and conduit penetrations. It prevents the migration of oil out of the containment. Fiberglass is impervious and the walls will prevent the horizonal migration of oil from the containment. Table 6—IEEE comparison of containment systems (continued) The liner is made from impervious material and prevents liquids from migrating out of the containment. © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. 33 Table continues The barrier wall is made from an impervious geosynthetic material. The wall has panels or “windows” spaced evenly along the length of the wall. The “windows” are filled with oleophilic polymer that allows water to pass through but swells and gels on contact with petroleum and stops all flow. The application allows storm water to pass laterally out of the containment but prevents oil from discharging from the containment. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Routine grading to reduce ponding. At grade No Yes Yes No Yes Generally, no. Maintenance requirements Above grade or below grade Hydraulic head required Effective in hot/ dry climates © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. 34 Effective in cold climates Storm-water restrictions Retrofit Stops catastrophic release Generally, yes. Generally difficult Yes. Must be drained in some manner. Yes Yes No Above or below Concrete should be inspected periodically to look for cracks, integrity issues, and standing water/oil. Generally, yes. Yes Yes. Must be drained in some manner if soil absorption and evaporation are not enough. Yes Yes No Above or below The containment should be inspected periodically for oil/water, erosion, and other damage. The stone layer should be maintained for fire-quenching. Generally, yes. Generally difficult No Yes No Yes Below The berms and outlet structure should be inspected periodically to confirm their integrity and function. Pond should also be checked to confirm it is holding the proper level of water. Control type Generally, yes. Yes Yes. Must be drained in some manner. Yes Yes No Above or below If installed uncovered, the containment should be inspected periodically for oil/water and damage. Generally, yes. Yes Yes. Must be drained in some manner. Yes Yes No Above The walls and seals must be inspected periodically to look for cracking or other damage Table 6—IEEE comparison of containment systems (continued) Generally, yes. Yes Yes. Must be drained in some manner. Yes Yes No Above or below No routine maintenance is required. Table continues Generally, yes. Yes Potentially. While selfdraining, the flow may have restrictions. Yes Yes No Below No routine maintenance is required. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. 35 N/A Yes, of the impacted stone. Seams Replacement after oil contact Easy Identification of leaks/spills Easy Generally no, unless the mat is designed in that manner. Fire quenching capability1 Ease of inspection No restrictions. Access to oilfilled equipment No, but often the stone will need to be replaced if applicable. N/A Easy to moderate if above grade. Could be difficult if below grade/involves confined space. Easy Possibly, if paired with stone layer of sufficient depth. Restricts access unless grating or other access is provided. Control type Potentially significant if liner is used Easy Easy No No restrictions. Possibly the stone No and a surface layer of clay. N/A Easy to Moderate if above grade. Difficult if below grade. Easy if above grade. Moderate to difficult if below grade. Often an observation well or sump is installed to alleviate inspection difficulty. No, unless below grade and backfilled with stone. Yes, if above ground; no if below grade. No, but often the stone will need to be replaced if applicable. N/A Easy if above grade and not filled with stone. Difficult if below grade/backfilled with stone. Easy if above grade. Moderate to difficult if below grade. Often an observation well or sump is installed to alleviate inspection difficulty. Yes, if backfilled with stone. Yes, if above grade; no if below grade. No, but often the stone will need to be replaced if applicable. Moderate Easy Easy to moderate Possibly, if backfilled with sufficient layer of stone. Restricts access. Table 6—IEEE comparison of containment systems (continued) No but often the stone will need to be replaced. Significant Difficult Moderate to difficult. Often an observation well or sump is installed to alleviate inspection difficulty. Yes, if backfilled with stone. No restrictions. Yes. The impacted barrier wall(s) and typically the stone will need to be replaced. Significant Difficult Moderate to difficult. Often an observation well or sump is installed to alleviate inspection difficulty. Yes, if backfilled with stone. No restrictions. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 16—Substation stone mat with perimeter stone berm 7.1.2.2 Oil-retention pits The containment systems described in this subclause assume the discharged oil to exist in bulk form or to be floating in bulk form on whatever residual water is present in the pit. When fire-suppression sprays are used to extinguish a transformer fire, the oil can become emulsified to some degree and could be discharged through a gravity type oil–water separator. This might necessitate that the containment pit be sized to contain both oil and the liquid from the fire-suppression spray and allow for quiescence for oil separation before discharge can occur. Figure 17 illustrates a typical oil-retention pit into which a pipe drainage system empties which is pictured in Figure 18. The drainage system network connects numerous collecting pits located under oil-filled pieces of equipment and directs surface water runoff and any potential oil spill to the retention pit. Figure 19 illustrates a typical cross section of the containment system and the design principle upon which this system is based. Oil, being less dense than water, will float on top of the water and is effectively contained on site by proper sizing of the pit and the design of the gravity separator. Generally, the pit is sized such that it will contain the entire quantity of discharged oil from the largest piece of equipment plus an assumed amount of retained water (see 7.1.1.2 for a discussion of volume requirements). The pit needs to retain water at the minimum water level (invert elevation) for the system to be fully effective at preventing the discharge of oil. Substation sites located in areas of porous soil, where the permeability is greater than 10−3 cm/s (see 7.1.1.3), should have their oil-collecting and retention pits lined (with a layer of clay, concrete, plastic, a rubber pit liner, etc.) to retain water and to prevent the migration of oil into the ground. Lined pits in locations with high water tables can be subjected to buoyant forces, and these forces need to be resisted to prevent the pit from floating or otherwise being displaced upward. 36 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 17—Typical oil containment system with retention pit Figure 18—Typical oil containment system where the entire substation drains to a retention pond that has an oil/water separator (inverted pipe) outlet 37 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 19—Cross section of oil containment system with retention pit Figure 20 is essentially the same as Figure 17, except the main oil-retention pit has been replaced with one of several possible discharge control systems that require less land area (also pictured in Figure 21). Due to the reduced footprint, this type of installation may be more practical at substations where the available land area is limited or in retrofit situations. Unlike the oil-retention pit, which is designed to contain the entire quantity of discharged oil plus an assumed amount of retained water from rain, snowmelt, water spray system discharge, and so on, this system is constructed such that any discharged oil backs up into the drainage system and remains contained in the various collecting pits beneath oil-filled equipment. Note that a negative consequence of this style of containment is the potential that spilled oil may back up into other equipment previously unaffected by the spill event but drains into the same system. Figure 20—Typical oil containment system with discharge control system 38 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 21—Typical oil containment system with a discharge control system with a stonefilled pit and aboveground fiberglass dike that drains through a polymer bead filter Figure 22 illustrates a concrete pit with photo examples shown in Figure 23, Figure 24, and Figure 25, which is used under individual major equipment units. Figure 26 illustrates an impervious liner over a pit dug in soil with a photo example shown in Figure 27, which is also used under individual major equipment units. Pit designs can be employed as either retention or collecting pits, depending on the method of discharge control. When located directly under large pieces of oil-filled equipment, the pit can be filled with stone for use in quenching oil fires (see 7.1.1.4). Annex B provides a method for calculating the containment volume of the stone using the void space. If open pits are employed, grating can be added to allow the operator safe access to necessary areas of the equipment. The perimeter of the containment systems should generally be located between 2 m and 3 m (6.6 ft and 9.8 ft) beyond the portions of the electrical equipment containing oil, based on the height of typical bushings and conservators. A larger pit size may be required to capture all of the oil contained in an arcing stream from a small puncture at the bottom of the tank (such as from a bullet hole). 7.1.2.3 Berms and dikes Secondary containment can be provided by creating a berm around the equipment. The impervious berm should be keyed into an underlying impervious layer on the site to protect against lateral movement of any released material through the soil and off site. If the soil conditions within the berm area are pervious, vertical movement through the berm into the ground should be reduced via a natural or an artificial liner, which may be installed within the perimeter. Berms and dikes can be constructed of soil, liner material, concrete, prefabricated panels of plastic/fiberglass materials, and/or oil absorbents and solidifiers, as shown in Figure 28, Figure 29, and Figure 30. In some applications, an earthen dike may be used around the entire substation perimeter or just the desired equipment, illustrated in Figure 31. While often an economical containment method, an earthen berm requires regular inspection to maintain its integrity. Figure 32 illustrates a typical portable secondary oil containment berm and tank. These devices are made of a self-supporting fabric liner and can be applied in emergency or temporary installations. They are inflated with air or filled with a liquid and are lightweight and compact for storage and transportation. 39 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 22—Typical concrete pit 40 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 23—Subsurface concrete containment pit with concrete wall under construction Figure 24—At-grade concrete containment with wall/dike Figure 25—Concrete containment pit with access grating Figure 26—Typical earthen pit with impervious liner 41 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 27—Earthen containment pit with impervious liner being installed Figure 28—Stone-mat containment with fiberglass dike Figure 29—Earthen containments with earthen berms all with stone-mat cover Figure 30—Portable containment for temporary/spare equipment 42 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 31—Typical oil containment system with earth dike 43 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 32—Typical portable berms and tanks 7.1.2.4 Oil absorbents and oil solidifiers Oil absorbents and oil solidifiers are used frequently to provide containment at substations. They are particularly useful in retrofit situations where there are space and construction limitations. The materials are composed of oleophilic, hydrophobic polymers, thus, allowing water to pass through while retaining oils. The materials most frequently used for containment are those products that are composed of cross-linked polymer chains that have a physical attraction to hydrocarbons caused by van de Waal’s forces. The long chains of hydrocarbons have a loose molecular structure and a very porous matrix. As they absorb and react with the oil, they increase the viscosity of the oil and in some cases bond with the oil to the point that it forms a solid mass. As the oil is absorbed and solidified, the material swells, stopping the flow of liquid. This property makes the material useful in berms and drain valves. The retained oil can be disposed of as solid waste and even recycled in some cases. These materials can be used either as “stand-alone” systems or in combination with the other containment systems to provide containment while allowing water to pass through. The oil absorbents and solidifiers can be 44 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations purchased in a variety of forms, including dry powder, granules, semisolid materials (e.g., pucks, cakes, balls, and sponge designs), and contained in booms, pillows, pads, socks, synthetic liners, and storm-water control valves. Since oil absorbents and solidifiers require replacement after exposure to oil, it is advisable that these materials are installed such that they are accessible and readily replaceable. Photos of oil absorbents and oil solidifiers are shown in Figure 33 through Figure 37. Figure 33—Fiber/geotextile berm containing “windows” of polymer beads Figure 34—Cross-section of fiber/geotextile berm showing layer of polymer beads Figure 35—Sump pump that pumps accumulated liquids through an in-line polymer bead filter 45 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 36—End-of-pipe polymer-filled filters attached to a header system where high stormwater flows are expected Figure 37—In-line oil-absorbing polymer bead filter ready for installation 7.2 Storm-water management and control An adequate and effective station storm-water management and drainage system is an essential part of any oil containment design. Drains, swales, culverts, catch basins, and so on, outside the station provide measures to divert water away from the substation. Underdrains and storm sewers inside the station can prevent flooding and if placed correctly can direct water away from oil-filled equipment. However, the liquid that accumulates in the collecting pits or sumps of oil-filled electrical equipment, and in the retention pits, and the site-wide runoff must be discharged. This liquid consists mainly of water (rainwater, melted snow or ice, water spray system discharges, etc.). Oil should be present only in case of an equipment discharge. Containment systems that discharge the accumulated water into the drainage system of the substation or outside the station perimeter may be equipped with a discharge treatment/control system. Before designing a storm-water management system or drainage system, federal, state, and local requirements on the quantity, rate, and quality of stormwater discharge during construction and operation of facilities should be determined. 46 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations 7.2.1 Examples of discharge control systems Containment dewatering systems and storm-water control systems can be either automated (passive or mechanical) or manual, and these systems can be used in association with containment around individual or grouped equipment and for area or site-wide drainage. Table 7 provides a comparison of various storm-water control systems. The comments in Table 7 are based on the manufacturer’s specifications and the experiences of the committee members. The controls that are described provide methods to release the accumulated water from the containment system while preventing the flow of discharged oil (oil is retained for later cleanup). In general, these discharge systems are independent of the containment methods described in 7.1.2. Any collected water should be released as soon as possible so that the entire capacity of the containment system is available for oil containment in the event of a spill. Where the ambient temperatures are high enough, evaporation may eliminate much of the accumulated water. Following is a more detailed description of the methods and systems covered in Table 7. 7.2.2 Oil–water separator systems Following are descriptions of several oil–water separator systems that rely on the difference in specific gravity between oil and water. Because of that difference, the oil will normally float on top of the water, allowing the water to act as a barrier and block the discharge of the oil. Oil–water separator systems require the presence of water to operate effectively and will allow water to continue flowing even when oil is present. Each of these devices requires a design that takes into consideration the rate and volume (e.g., liters/minute or gallons/minute) of flow that will discharge through the structure to reduce any turbulence that would emulsify the oil in the water. Under some turbulent conditions, some of the resuspended or emulsified dielectric oil could potentially pass through an oil–water separator system. Use of more sensitive discharge control systems should be considered where stringent governmental regulations do not allow for even small amounts of oil to be discharged. A combination of discharge control systems may be required to be effective. Figure 38 illustrates the detail of an oil–water gravity separator that is designed to allow water to discharge from a collecting or retention pit, while retaining the discharged oil and is pictured in Figure 39. Figure 38—Oil–water gravity separator (for warm climates) 47 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. Application Oleophilic polymer in-line filter Placed in-line in a storm drainpipe and typically in a specially constructed sump. Can be used for drainage from whole sections of the substation or to drain containment around single pieces of oil-filled equipment. Oleophilic polymer end-of-pipe filter Typically placed at the downstream end of storm drain discharge pipe or on a gate valve draining a containment. The unit simply attaches to the pipe/valve. Comes in various diameters. Typically used in containment for a single piece of equipment although multiple units can be installed on a header system to accommodate higher flow requirements for draining multiple pieces of equipment. Placed in a sump with a sump pump. Can be used to drain the containment around single pieces of oilfilled equipment or to drain sections of an entire substation. Sump pump that is equipped with an oilsensing, conductivity meter actuated alarm/ shut-off system Control type Placed in-line in a specially constructed catch basin/vault. Can be used to drain the containment around single pieces of oilfilled equipment or if sized correctly to drain whole sections of the substation. Specific gravity actuated valves Placed in-line in existing catch basins or storm-water basins. Typically found at old substations and used to drain the containment of a single piece or in the case of ponds, multiple pieces of oil-filled equipment. Table continues Placed in-line or at the end of storm sewers. Typically used to drain whole sections of the substation. Oil/water separator— Oil/Water catch basin/pond type separator—vault type Table 7—Comparison of environmental storm-water control systems IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. 48 Theory of operation The filter is filled with oleophilic polymer that allows water to pass-through. The polymer absorbs petroleum products and upon contact swells and forms a gel. The gel eventually blocks all flow and prevents oils from discharging. Water flows vertically or horizontally through the filter. The filter is filled with oleophilic polymer that allows water to pass-through. The polymer absorbs petroleum products upon contact swells and forms a gel. The gel eventually blocks all flow and prevents oils from discharging. The system is equipped with a conductivity probe that senses the presence of oil by measuring a decreased conductivity of the fluid, then shuts off the sump pump so no oil is discharged. The sump pump has high level and low-level float switches and alarms. Control type The valve is a float valve that closes when oil is present in the vault. The valve operates on the principles of buoyancy. The ballasted float, which is the only moving part, is weighted for a specific gravity typically between 0.90 and 0.95. In the water, the float will float and keep the valve open. An accumulation of oil around the float will decrease the buoyant force on the float causing it to sink lower in the liquid. As the oil accumulation increases, the float will sink lower and finally close the valve when the oil level is sufficient. Simply an “L” shaped outlet pipe placed so that the basin will drain from near its bottom. Oils float on the surface and the clean water discharges from the bottom of the basin. Table 7—Comparison of environmental storm-water control systems (continued) Table continues A prefabricated vault containing a single or a series of baffles that are designed to skim and retain oil at the surface and allow only clear water to discharge. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. 49 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. 50 Yes Potentially significantly—requires a pre-filter and regular inspection. No Yes Potentially significantly—requires a pre-filter and regular inspection. Yes Mechanical parts Hydraulic head required Effected by sediment Effective in hot climates Yes No Varies, typically up to 500 GPM max. Varies, typically up to 500 GPM max. Filter requires periodic inspection for clogging by sediment or debris and as-required cleaning/replacement of sediment pre-filter. Max flow (GPM) Maintenance requirements Filter requires periodic removal for inspection and cleaning/replacement of the internal sediment pre-filter. Yes No No Yes Yes Minimal Varies, typically up to 1400 GPM max. The water level in the catch basin must be maintained at the invert elevation of the discharge pipe or the valve will close and prevent flow. Some models are equipped with “slave valves” that are supposed to force the stop valve open when water enters the catch basin. The valve can also be opened manually by lifting the valve off its seat with an attached wire. The system needs to be inspected frequently to confirm that the valve is open to prevent flooding. It does take a large volume of oil present in the manhole for the valve to close. No Yes Varies, but typically ~74 GPM under normal operation. The conductivity probe and support bracket must be cleaned periodically as contact of the probe with debris can cause false alarms. The pump is to be inspected and lubricated per manufacturers specifications. May need periodic calibration. Control type Possibly not if using an open basin design. No Yes No Varies The water level in the basin must be maintained at the invert elevation of the discharge pipe or the separator will be ineffective. Must be periodically cleaned to remove floating oil and any sediment that may accumulate at the bottom and plug flow. Table 7—Comparison of environmental storm-water control systems (continued) Yes Yes No No Varies Table continues The water level in the basin must be maintained at the invert elevation of the discharge pipe or the separator will be ineffective. Must be periodically cleaned to remove floating oil and any sediment that may accumulate. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Yes Yes, provided manhole/ vault and upstream containment is sized appropriately. Yes, Yes Yes, provided containment is sized accordingly. Yes Yes Storm-water flow restriction Retrofit Stops catastrophic release Effective in sheen removal Replacement after oil contact Yes High potential—must be sized appropriately. High potential—must be sized appropriately. Effective in cold climates Potential for decreased effectiveness and freezing Potential for decreased effectiveness and freezing. No Yes Yes, provided manhole/ vault and upstream containment is sized appropriately. Yes No Potential for freezing outlets. Control type Difficult for open pond/basin design. No Yes No Yes. The ability to contain emulsified oil is unknown however. No Yes. The ability to contain emulsified oil is unknown however. Yes, provided manhole/ Yes, provided basin and vault and upstream upstream containment containment is sized is sized appropriately. appropriately. Yes No Yes Table 7—Comparison of environmental storm-water control systems (continued) No No Yes, provided manhole/ vault and upstream containment is sized appropriately. Yes Not typically. No IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. 51 IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 39—Simple inverted outlet, oil-water, gravity separator The separator in Figure 40 is similar to that in Figure 38 except that it is designed for stations located in areas with freezing temperatures. The depth of the discharge pipe would be determined relative to the average penetration of frost for the specific area of installation. Figure 40—Oil–water gravity separator (for cold climates) Figure 41 illustrates another type of oil–water separator. This separator consists of a concrete enclosure, located inside a collecting or retention pit, and connected to it through an opening located at the bottom of the pit. The enclosure is also connected to the drainage system of the substation. The elevation of the top of the concrete weir in the enclosure is selected to be slightly above the maximum elevation of discharged oil in the pit. In this way, the level of liquid in the pit will be under a layer of fire-quenching stones where a stone-filled pit is used. During heavy accumulation of water, the liquid will flow over the top of the weir into the drainage system of the station. A valve is incorporated into the weir. This normally closed, manually operated valve allows for a controlled discharge of water from the pit when the level of liquid in the pit and enclosure is below the top of the weir. 52 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 41—Oil–water separator at the oil retention pit Figure 42 illustrates a simple, inexpensive oil–water separator unit that could be effective in draining water from an oil sump. Figure 42—Simple oil–water separator Figure 43 provides a typical detail of an oil-trap-type oil–water separator. In this system, the oil will remain on top of the water and not develop the head pressure necessary to reach the bottom of the inner vertical pipe. For this system to function properly, the water level in the manhole portion of the oil trap needs to be maintained at an elevation no lower than 0.6 m (approximately 2 ft) below the inlet elevation. This will result in an adequate amount of water being available to develop the necessary hydraulic head within the inner (smaller) vertical pipe, thereby preventing any discharged oil from leaving the site. It is important to note that the inner vertical pipe should be extended downward past the calculated oil–water interface elevation sufficiently to protect 53 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations against the oil discharging upward through the inner pipe. Likewise, the inner pipe needs to extend higher than the calculated oil level elevation in the manhole to protect against the oil from draining downward into the inner pipe through the vented plug. The reason for venting the top plug is to maintain atmospheric pressure within the vertical pipe, thereby preventing any possible siphon effect. This type of separator can easily be installed in existing catch basins to retrofit storm sewer systems for containment. Figure 43——Oil-trap-type oil–water separator 54 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations 7.2.3 Flow blocking systems Several oil-flow blocking systems that do not require the presence of water to operate effectively are described in this subclause. These systems detect the presence of oil and block all flow (both water and oil) through the discharge system. The best of these systems have been shown to be the most sensitive in detecting and blocking the flow of oil. However, they are generally of a more complex design and may require greater maintenance to maintain continued effectiveness. In addition to Figure 35, Figure 36, and Figure 37, Figure 44, Figure 45, and Figure 46 illustrate a method that uses oil absorbents or solidifiers to block the flow of oil. Some of these materials have the property to absorb as much as 27 times their original volume, and to swell to 3 or 4 times their original diameter. They are hydrophobic and will not, even partially, absorb water or brine solutions. By swelling or solidifying in the presence of oil, this polymer material will plug the berm, pipe, or drain in which it is located, blocking the flow of any discharged oil. The diameter of the drainpipe and the thickness of the polymer layer have to be carefully selected to provide the proper water flow and oil-retaining capabilities. A filter layer placed on top of the main polymer bed will retain impurities and silt contained in the incoming liquid, absorb any trace amounts of oil present, and reduce the frequency of maintenance work on the main polymer layer. It also reduces the flow speed of the liquid, allowing a longer contact of oil with the absorbing media, thereby increasing the efficiency of the method. However, over time, as the silt accumulates in the filter layer, it can block the flow of water and require cleaning or replacement of the filter layer. In addition to catch basin and discharge pipe applications, the polymer material also can be purchased in forms that are designed to be inserted in the floors and walls of dikes and berms. Figure 44—Oil-absorbing polymer bead bed (installed in manhole) 55 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 45—Imbiber valve concrete structure with valve removed showing concrete structure and outlet pipe Figure 46—Oil-absorbing polymer bead bed (installed in drain pipe) Figure 47 illustrates an oil stop valve installed inside a catch basin and is pictured in Figure 48 and Figure 49. The valve has only one moving part, a ballasted float set at a specific gravity between that of oil and water. When oil reaches the manhole, the float in the valve loses buoyancy and sinks as the oil level increases until it sits on the discharge opening of the valve and blocks any further discharge. When the oil level in the manhole decreases, the float will rise automatically and allow discharge of water from the manhole. Some oil stop valves have a weep hole in the bottom of the valve that allows the ballasted float to be released after the oil is removed. This can cause oil to discharge if the level of the oil is above the invert of the discharge pipe. 56 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 47—Oil stop valve Figure 48—Specific gravity type oil stop valve ready for installation Figure 49—Oil stop valve being installed in a manhole 57 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations The oil stop valve is normally used in a catch basin that retains water, thus, allowing the ballast to “suspend” in the water column and allow water flow when oil is not present in the basin. Additional parts are available that will allow the oil stop valve to function in a catch basin that is normally dry. Additional consideration should be given to the size of the vault or catch basin in which the oil stop will be installed. It should be large enough to accept the anticipated storm-water flow and allow for some settling and separation of oil and water, in the event of an oil release, to avoid an emulsified oil–water mixture. Figure 50 illustrates a discharge control system consisting of an oil-detecting device and a pump installed in a sump connected to the collecting or retention pits of the oil containment system and is pictured in Figure 51. The oil-detecting device may use different methods of oil sensing (e.g., conductivity probes, turbidimeters, and fluorescence meters). The conductivity probe shown detects the presence of oil on the surface of the water, based on the significant conductivity difference of these two liquids and, in combination with liquid level switches, stops the sump pump when the water–oil separation layer reaches a preset height in the sump. The systems provide continuous positive site drainage while still containing any released material on the site. Transformer low oil level or gas protection can be added into the control diagram of the pump in order to increase the reliability of the system during major spills. These systems can be retrofitted in existing sumps and catch basins although care should be made in setting the meter depth, the high-water level, and the depth and slope of the discharge pipe in cold climates as the function of the system can be affected by ice formation. 7.2.4 Manual pumps and valves Some containment systems, collecting pits, retention pits, or tanks have no link to the drainage system of the substation and have no automatic dewatering system. Discharge of the liquid accumulated in these systems requires the use of permanently installed or portable pumps, or manual drain valves. The pumps and valves are manually activated by operating personnel. This system requires periodic inspection to determine the level of water accumulation. Before pumping any accumulated liquid, an inspection is required to assess if the liquid to be pumped out is contaminated. Oil absorbent or solidifier systems can be attached to the end of the discharge pipes from these manual systems to confirm that no oil is discharged. Figure 52 and Figure 53 illustrate the discharge control system using an in-line, manually operated, normally closed valve. This valve is opened to drain water from the containment pit after it has been determined that no oil is present. It is generally applied in the bottom of shallow containment pits. If used in cold weather areas, freezing of the valve is normally not a problem since moisture content from snow accumulation is usually less than the rainfall amount used to determine the height of the curb. Care should be taken to keep the containment drained just prior to winter freezing. Close attention will also be needed in the spring when melting of the snow and ice and spring rains may require more frequent draining of the containment system. 58 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 50—Sump pump water discharge (with oil-sensing probe) 59 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Figure 51—Oil-sensing pump system Figure 52—Mud valve Figure 53—Polymer bead filter fitted on end of manual valve 7.3 Warning alarms and monitoring In the event of an oil spill, it is imperative that cleanup operations and procedures be initiated as soon as possible to prevent the discharge of any oil, or to reduce the amount of oil reaching navigable waters. Hence, it may be desirable to install an early detection system for alerting responsible personnel of an oil spill. Some 60 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations governmental regulations may require that the point of discharge (for accumulated water) from a substation be monitored and/or permitted. The most effective alarm is one that is activated by the presence of oil in the containment system. Also, a low oil-level indicator within the oil-filled equipment can be used; however, it may not activate until 3% to 6% of the transformer oil has already discharged. In cases where time is critical, it may be worthwhile to also consider a faster operating alarm such as one linked to the transformer sudden gas pressure relay. Interlocks may be considered as a backup to automatic pump or valve controls. Other less critical maintenance alarms may also be considered where applicable. These include pump failure and high water-level alarms. Alarms should be transmitted via supervisory equipment or a remote alarm system to identify the specific problem. The appropriate personnel are then informed so that they can determine if a spill has occurred and implement the SPCC contingency plan. The use of alarms and monitoring practices was surveyed in 1992. Only 14 of the responding utilities (24%) monitored the discharge point, and nine utilities (15%) employed alarms at the discharge point. 7.4 Maintenance of oil containment systems One design criterion of any oil containment system is to reduce maintenance requirements; however, some prudent maintenance practices are required. Maintenance of oil containment system components may involve the following: a) Regular inspection of associated manholes, standpipes, and so on, and cleaning out of debris and/or pumping out of excess standing water. b) Regular inspection of systems that require the presence of water to function effectively to maintain the minimum level of water. c) Regular inspection of discharge lines to verify that no external blockage could restrict water flow. d) Periodic operational inspection of piping either during or after a significant rainfall or weather event to assess performance of the system. If indications are that the system is not functioning, manual flushing of drain lines may be required. e) Regular inspection of open containment pits and pumping out any excess water (maintaining any minimum water level required) to prevent stagnation during dry periods; to discourage nesting or other activity by birds, rodents, and insects; and to maintain maximum capacity and function of the oil containment system. f) Yearly inspection of berms around oil containment pits to verify that erosion or foot and vehicle traffic has not caused a breech in the berm. g) Seasonal inspection of oil containment facilities during prolonged cold periods accompanied by large snowfalls and ice buildup. In the event of an oil spill, it may be possible for oil to initially flow on top of the ice and overflow the oil containment system. h) Regular inspection and sampling of the system to check for the presence of oil contamination. i) Manufacturers’ instructions on equipment maintenance should be closely followed. The following items may be required regularly: 1) Separators. Remove sludge. 2) Filters and oil-absorbing/solidifying polymers. Clean or replace as required. 3) Pumps and valves. Check operation periodically. 4) Oil probes, monitoring equipment, and alarms. Check operation and calibration periodically. 61 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations 8. Control and response Control of the oil flow will be required in the event of a spill. The successful use of secondary containment may still require some amount of cleanup. It is the function of a “spill response plan” to document and prove that all relevant aspects of the control, containment, and cleanup have been considered and are executed correctly at the time of the spill. Even where secondary containment is not required, some regulations, including SPCC regulations found under 40 CFR, Part 112, stress the need to include site-specific information in the plan. 8.1 Typical spill response plan requirements Response plans should focus on containment of oil and include specific information about location of equipment, sources of potential spills, quantities of oil that could be discharged, drainage pattern, rate of flow, and containment measures. Additionally, one important requirement of the plan is the countermeasures plan for cleanup should a spill occur. If an oil spill occurs, procedures outlined in this plan should be activated. Another important function of a response plan is its ability to demonstrate to local, state, and federal authorities that the user has addressed the problem of oil spills and installed effective containment and control measures and is prepared to act in the event of a spill occurrence. Each utility’s response plan will be different and written to reflect that utility’s own unique requirements and policies. Furthermore, each substation owner or operator needs to ensure their response plan meets the applicable regulatory requirements of the jurisdiction the facility is found in. For example, in the United States, the elements listed in 40 CFR, Part 112.6 shall be referenced when developing the plan. For the purposes of this Guide, items described below are common components found in typical spill response plans. Please note that some of these components are not required by 40 CFR, Part 112. a) b) General information: 1) Introduction, purpose, and scope 2) Applicable local, state, and federal regulations 3) Applicable corporate policies and procedures 4) Requirements for review and approval, both by management and a registered PE, and the plan updating procedures, including the maximum time interval between reviews (required under SPCC) 5) Any certification requirements, including that by the PE Identification information: 1) Substation name, type of facility, mailing address and street address (if different), legal description or GPS coordinates, facility contact phone number, and date and year that the facility began operation 2) Name, title, address and phone numbers for the designated spill prevention and control coordinator(s) including on-site coordinator, responsible supervisor, and applicable company departments and managers (operations, legal, environmental, public relations, etc.) 3) Emergency 24 h phone number(s) for the designated spill coordinator(s) and any on-site and management personnel to be contacted immediately 4) Map of the substation showing the relative location to the surrounding area, including nearby roads, waterways, wells, sewers, drains, ditches, or other facilities that could be impacted or contaminated by an oil spill or serve as a migratory pathway for a spill 5) Name, address, and 24 h emergency phone number(s) of the designated spill cleanup contractor(s), and written documentation of emergency response arrangements 62 © 2022 IEEE. 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IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations 6) c) d) e) Designated noncompany contacts (name, title, address, and 24 h emergency phone numbers), including the EPA or regulatory authority regional office; coast guard; state environmental departments; local governmental, health, fire, and police authorities; state police; and local wastewater treatment facilities Material used or stored at substation: 1) Name and trade name for the oil and chemicals of concern 2) Physical characteristics of the oil and chemical including composition, concentration, and possible reactions with other mixtures 3) List of all the equipment containing oil, describing the number of units, quantities of oil present (including total maximum volume), unit identification, unit oil volume(s), PCB content, and type of tank or container 4) Map or site plan of the substation showing location of tanks and oil-filled equipment, spill discharge control points and predicted direction and path of an oil spill, including locations of transformers, circuit breakers, and other oil-filled electrical equipment; aboveground and belowground bulk storage tanks; alarms; discharge points; floor drains; secondary oil containment; sump pumps; critical valves; environmental controls, etc.) 5) Security procedures, requirements, and measures employed at the substation Spill control and response: 1) Staff training requirements, including frequency of training 2) Spill response procedures (including the employee assignments and the specific actions to be taken) describing the methods of containing and cleaning up oil spills (such as skimming, boom construction and deployment, use of special oil-absorbent materials, use of machinery or special tools, etc.) 3) Spill response equipment including oil-absorbent material, booms, pumps, vacuum trucks, boats, skimmers, hoses, and other miscellaneous equipment; identifying its location and who to contact to obtain it (often a cleanup kit inventory is provided listing quantity of each item required, stock numbers, etc.) 4) Spill incident reporting procedures (see Annex A for a typical notification form) including stepby-step calling procedures for immediate and follow-up notifications, identification of required reports and written notification(s) and their timing (reports should include the location of the spill, material type and quantity spilled, extent of the spill, media impacted and action taken) 5) History and analysis of past oil spills at the facility including type and amount of oil spilled; location, date, and time of spill; water course affected and resulting damage; cause of spill; cost of the damage and cleanup; and actions taken to prevent future spills 6) Surveillance requirements including watch and inspection schedule, description of duties, and alarm procedures 7) Record-keeping, testing, and inspection requirements, including inspection for oil leaks, tank integrity, secondary containment and environmental control integrity and cleanup equipment Secondary oil containment: 1) Design, construction, physical features, materials used, intended function, and operation of all secondary containment facilities (including retention pits, valves, pumps, oil–water separators, diking, etc.) 2) Volume requirements, dimensions, and calculations, including any special conditions or requirements that should be met to maintain proper operation of the containment system 3) Drainage requirements and restrictions, including release of accumulated water 63 © 2022 IEEE. 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IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations f) 4) Oil transfer procedures for pipelines, trucks, and oil-handling equipment 5) Maintenance requirements Environmental equivalency and contingency (applicable to SPCC regulated facilities): 1) Determination of secondary containment impracticability, certified by a PE 2) Description of environmental equivalencies and other provisions provided in lieu of traditional secondary containment facilities, certified by a PE 3) Oil spill contingency plan, as described in 40 CFR, Part 109.5, for qualified oil-filled operational equipment where traditional containment may be impracticable because of design and safety considerations and site configuration 8.1.1 Spill prevention control and countermeasure (SPCC) regulations and categories Provided a US-based facility/substation exceeds the aggregated oil storage capacity criteria for SPCC plan development [at the time of publication, 4997 L (1320 gal)] and where, due to their location or quantities of oil involved, it is possible for a discharge of oil to reach navigable waters as defined in 40 CFR, Part 112.1(b), substations are subject to SPCC regulations. If the requirements are met, substations may be classified into Tier I and Tier II facilities. The current SPCC regulations have a tiered structure for the development of the spill plans. Facilities that qualify for the tiered approach are those that: a) Have total aboveground oil storage capacity of 37 854 L (10 000 gal) or less b) Within three years prior to the SPCC plan certification date, have not had either: 1) A single discharge of oil to navigable waters or adjoining shorelines exceeding 3785 L (1000 gal) 2) Two discharges of oil to navigable waters or adjoining shorelines, each exceeding 159 L (42 gal) within any 12-month period Tier I qualified facilities are those that have no individual aboveground oil containers greater than 18 927 L (5000 gal) and store less than 37 854 L (10 000 gal) total. These facilities can complete and self-certify the SPCC plan template (Appendix G to 40 CFR, Part 112) in lieu of a full professional engineer (PE)-certified plan or other self-certified SPCC plan. Tier II qualified facilities are those that have an individual aboveground oil container greater than 18 927 L (5000 gal) and store less than 37 854 L (10 000 gal) total. These facilities must have a full SPCC plan but can self-certify the plan in accordance with all applicable requirements of §112.7 and subparts B or C of the rule, in lieu of a PE-certified plan. If the facility is not qualified to use the tiered approach, the plan requires review and certification by a registered PE that has become familiar with these regulations, has visited and examined the facility, concurs that good engineering practices have been used, and verifies that appropriate procedures for testing and inspection have been established and that the plan is adequate for the facility. The SPCC plan and appropriate containment can include the use of dikes, berms, curbing, culverts, weirs, absorbent materials, sumps, and collecting systems designed for the purpose of containing the discharge of harmful quantities of oil. In summary, this requirement specifies that a properly engineered plan shall be developed and documented to demonstrate the containment of the surface discharge of oil from a storage container at a facility that, due to its location, could reasonably be expected to discharge oil into or upon navigable waters in sufficient quantity to cause an oil sheen, or that adequate response and cleanup measures are in place if containment can be shown to be not practicable. 64 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations 8.1.2 Reporting procedure An appreciable discharge of oil from transformers, circuit breakers, or other electrical equipment is a possible result of electrical failure of that equipment. These types of failures can be detected by alarms either directly from attended substations or transmitted by supervisory equipment, or by customer calls to dispatching centers as a result of equipment outage. Slow leaks from electrical equipment or oil-storage facilities can be detected and corrected during periodic and routine inspections. It is the responsibility of any employee visiting a facility to immediately report an oil spill to the appropriate company personnel. Governmental agency notifications may also be required. 8.1.3 Action to be taken in the event of an oil spill See Annex A for a typical notification form. A list of personnel to be contacted should also be included as an attachment to a response plan. Action to be taken includes the following: a) Determination of the source of the spill b) Initiation of action to stop source of spill within the limits of training, experience, and safety (e.g., close necessary valves or temporarily plug holes to stop or control spill) c) Determination of the approximate volume, size of the spill, PCB classification, and direction of flow d) Notification of the appropriate personnel including regulatory agencies e) Containment of any oil spill by blocking flow to drains and waterways, digging diversion ditches, sandbagging, or through other means f) Containment of any oil that has reached a waterway to prevent any further spreading downstream (by using booms or other means) g) Cleanup of oil by using absorbent materials, pumping, and removing oil-saturated earth or stone, as required Oil spill cleanup material should be provided. Materials available and their respective locations should be included in or listed as an attachment to the facility spill response plan. 8.2 Control and cleanup in substations Control is the most important act in responding to an oil spill as it is used to prevent the spread of the oil, and thus, it reduces environmental damage. Successful control is highly dependent on response time, which in turn is dependent on many variables; some are geographic features, equipment design, and availability of trained personnel. All substation personnel should be instructed in steps to be taken immediately to stop the source of the spill and other emergency measures that can be undertaken to prevent or control a discharge from the station. Typical control methods are as follows: a) Absorbent material: There is a vast array of natural and synthetic absorbents. Common in the industry is the use of synthetic polymer absorbents pads, booms, and blankets. Inorganic absorbents, such as clay-based granular material, is also very common and widely used to control a spill at its source and prevent it from spreading. b) Control dams and berms: Often, control dams, constructed of earthen or absorbent material, can be effective at stopping and controlling oil spills in a substation, preventing the oil from migrating 65 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations outside the property. For spills that get into site drainage structures and ditches, control dams offer a good choice for trapping oil. c) Booms: A device placed mainly on water surfaces, such as drainage structures and ditches, but can be used along the ground surface, to serve as a barrier to the movement of oil across a designated plane. There are many different types, shapes, and sizes of booms, which basically trap floatables at the surface while permitting the flow of water under the boom. Some boom is absorbent while others are strictly containment boom. d) Drain plugs and covers: A variety of inflatable drain plugs and heavy rubber mat-type drain covers can be used to prevent infiltration of oil into a drainage structure, such as a catch basin or outlet culvert. e) Deactivation of station pumps: Often, substations will contain sump pumps, in either drainage or electrical conduit structures or substation buildings, such as control houses; these will serve as a means of off-site migration if spilled oil were to flow to these pumps. Affected sump pumps should be turned off in the event of an oil spill. 8.3 Disposal Contaminated materials such as oil-soaked gravel, soil, rags, and sorbent materials should be handled and disposed of carefully. The area of each company responsible for environmental issues should be contacted for the proper disposal method. If a cleanup contractor is utilized, that contractor should also be consulted as to the proper methods for disposal of the various contaminated materials. Recycling is an option that may be considered. Disposal methods and sites will vary based on the state and local environmental regulations that may apply. 8.4 Maintenance of equipment A periodic inspection of all oil cleanup materials and equipment (i.e., booms, sorbents, and pumps) should be conducted. Each manufacturer’s recommended storage conditions and shelf life should be reviewed to determine the material’s usability in the event of an oil spill. A record of the inspections should be maintained by the substation owner/operator, and in some cases, it may be prudent or required to keep them within the spill response plan relevant to that site (at the site or at corporate headquarters). If the inspection reveals a need to replace outdated or damaged cleanup materials, a follow-up inspection should occur to verify that materials have been replaced. 66 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Annex A (informative) Typical information included in notification form and spill report7 Date: Name of company: Date of spill: Time of spill: Location of spill (city/town, county, state): Time and location where samples were taken: Total quantity spilled ____ liters (gallons) of ____ (type of material) Name of receiving body of water: Quantity reaching the water body: liters (gallons) Description of spill (probable source, cause of spill, and extent):____ Actions initiated to contain or clean up: Measures that can be taken to prevent future spills: Person(s) to contact on scene: Name(s): Phone number(s): Report initiated by: Name: Title: Phone: EPA person notified: Name: Date: Time: Title: Phone: 7 This is a general form representing a compilation of items found in a typical notification form and spill report. Each user’s form will be different, written to reflect the user’s own unique requirements. 67 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Other person(s)/agencies notified (fire, police, company legal department, company environmental department, company public affairs): Name: Date: Time: Title: Phone: Date and time spill cleanup was completed: 68 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Annex B (informative) Collecting pit volume calculation As an example, assume a collecting pit filled with large stones [assume 3.8 cm (1.5 in) diameter rock with a 35% porosity] that is designed to contain 50 000 kg (110 000 lb) or approximately 56 780 L (15 000 gal) of oil. Also, assume that the pit is dry before the discharge occurs and no liquid will leave the pit during the period of the oil spill. The size of the collecting pit needed to provide a fire-quenching capability and the needed volume for oil containment can be calculated as follows. The area encompassed by the arrangement of the transformer, its coolers, and its conservator tank is presented in Figure B.19. The pit extends a minimum of 2.0 m (6.6 ft) beyond any part of a transformer filled with oil (see 7.1), resulting in a minimum pit area of 14.0 m × 16.0 m (45.9 ft × 52.5 ft), or 224 m2 (2410 ft2). However, the area within the pit occupied by equipment foundations is approximately 18 m2 (194 ft2), reducing the effective containment area to 206 m2 (2216 ft2). 9 Notes in text, tables, and figures of a standard are given for information only and do not contain requirements needed to implement this standard. 69 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations NOTE—The conversions in Figure B.1 have been approximated from metric units. Figure B.1—Oil collecting pit The volume of oil in the transformer is 60 m3 (2117 ft3), which is calculated by dividing the 50 000 kg (110 000 lb) of oil in the transformer by the 833 kg/m3 (52 lb/ft3) density of oil factor. The volume of water (from rain or a water spray deluge system—whichever is greater) has to be added to the volume of oil. This example assumes that no deluge system is present and that a 30 mm (1.18 in) rain will fall during the duration of a discharge. Therefore, the volume of water is 5.9 m3 (209 ft3), which is calculated by multiplying the entire area of the pit (including foundations) by 0.03 m (0.1 ft). The resulting total volume of oil and water is 65.9 m3 (2326 ft3). The pit volume required to contain this volume of liquid in the voids of stones is 188.3 m3 (6646 ft3), which is based on the total volume of oil and water divided by the porosity of the crushed stone. The pit depth needed to meet the containment requirements is 1.06 m (3.5 ft), which is calculated by dividing the total volume requirements of 188.3 m3 (6646 ft3) by the 177 m2 (1902 ft2) effective containment area of the pit. An additional 0.3 m (12 in) of quenching stone is added to avoid a pool fire, which brings the depth of the stone layer to 1.36 m (4.5 ft). The top of the stone layer will normally be at the same elevation as that of the finished grade outside the pit (see Figure 16). An additional 0.3 m (1 ft) of curb (located above finished grade elevation) around the pit could also be added to protect the pit filled with stones against silting by yard gravel and sand. The depth of the pit may take into consideration the possibility of freezing temperatures as coarse crushed stone does not provide protection against frost penetration of foundations. 70 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Annex C (informative) Summary of past IEEE oil containment surveys C.1 1992 IEEE survey The 1992 IEEE survey addressed the factors used to determine where oil-spill containment and control programs are needed. Based on the survey, the criteria in Table C.1 are considered when evaluating the need for secondary oil containment. As for specific numerical limits, 57% of the respondents install secondary containment when the maximum volume of oil per individual tank exceeds the 2498 L (660 gal) 40 CFR, Part 112 limit (at time of survey), with a range of 11 356 L (3000 gal) reported. More than 82% of respondents also limit the total volume of oil in the substation to the 4997 L (1320 gal) specified in 40 CFR, Part 112, with a range of 5678 L (1500 gal) reported. The 1992 IEEE survey provided no clear-cut limit for the proximity to navigable waters. Relatively equal support was reported for several choices over the range of approximately 457 m (1500 ft). Rarely is all of the equipment within a given substation provided with secondary containment. Table C.2 lists the survey results identifying the equipment for which secondary oil containment is provided. None of the remaining equipment surveyed, which included voltage and current transformers, capacitors, and all mobile devices, received a rating higher than 15%. The focus is clearly on the equipment that contains the largest quantities of oil (see 5.1). As for specific minimum voltage and/or megavolt-ampere (MVA) criteria above which a user always installs secondary containment, a wide range of figures was reported. For voltage, the minimum criterion was most often 115 kV, with a range of 69 kV to 345 kV reported. For MVA, the minimum criterion was most often 10 MVA, with a range of 5 MVA to 45 MVA reported. Table C.1—Secondary oil containment evaluation criteria Criteria Utilities responding that apply this criteria (%) Volume of oil in individual device 88 Proximity to navigable waters 86 Total volume of oil in substation 62 Potential contamination of groundwater 61 Soil characteristics of the station 42 Location of substation (urban, rural, remote) 39 Emergency response time if a spill occurs 30 Failure probability of the equipment 21 Age of station or equipment 10 Table C.2—Secondary oil containment equipment criteria Equipment Utilities responding that provide secondary containment (%) Power transformers 86 Aboveground oil storage tanks 77 Table continues 71 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Table C.2—Secondary oil containment equipment criteria (continued) Equipment Utilities responding that provide secondary containment (%) Station service transformers 44 Oil circuit breakers 43 Three-phase regulators 34 Below-ground oil storage tanks 28 Shunt reactors 26 Oil-filling equipment 22 Oil-filled cables and terminal stations 22 Single-phase regulators 19 Oil circuit reclosers 15 From the 1992 IEEE survey results, it became clear that no single containment system or discharge control method is preferable. All methods have been utilized successfully and are ranked in Table C.3 in order of survey preference. There appears to be some correlation to the cost and complexity of the system, with the less expensive, simpler systems being employed most often. As to effectiveness, it was common for each individual user to favor their method. As a result, the reported effectiveness results were inconclusive. Very few utilities reported a measured effectiveness. The effectiveness ratings appeared to be somewhat subjective and based as much on the inconveniences associated with the application of the method as any other criteria, due in some part to the lack of testing and very few actual spills. Table C.3—Containment method utilization Containment system or discharge control method Utilities responding that employ method Figure reference For new substations (%) For retrofits (%) Perimeter or equipment berm Figure 31 and Figure 32 67 58 Fire-quenching and oil-retention pit Figure 22, Figure 26, and Figure 41 60 42 Oil-retention pit Figure 17 and Figure 19 48 43 Oil–water separator Figure 42 41 27 Oil-detection-triggered sump pump Figure 50 and Figure 51 31 39 Gravity separator Figure 40 24 15 Oil–water stop valve Figure 47 22 35 Gravity separator Figure 38 15 10 Oil trap Figure 43 8 14 Oil-absorbing polymer bead bed Figure 44, Figure 45, and Figure 46 8 17 The storm-water event design criteria employed ranged from 5 cm to 20 cm (approximately 2 in to 8 in) of rainfall within a short period of time (1 h to 24 h). A total of 79% of the 34 responding utilities said that their containment pits are designed to hold either 50% to 100% (15 utilities) or 100% to 125% (19 utilities) of the unit’s oil volume. More than 88% of the responding utilities filled the pits located directly under oil-filled equipment with crushed rock or stone. The size of the stone used varied in the range of 1.9 cm to 7.6 cm (0.75 in to 3.0 in). Depending on the uniformity of stone size used, the void volume ratio may vary from 20% to 50%. Some of the users surveyed expressed concern that pits with small stones can become plugged by silt accumulation, indicating that larger stones may be more suited for oil containment areas. 72 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Based on the 1992 IEEE survey results as shown in Table C.4, users typically either line all of their pits or are very selective and line less than 25% of their pits. Greater than 42% of the utilities responding said that they evaluate the soil characteristics to determine whether a pit should be lined. As with the containment systems, the type of liner used seems to be governed primarily by user preference. All of the liners listed in Table C.4 have been applied with success. Table C.4—Containment pit liners Liner type No. utilities that use this type of liner No. years experience with the liner Concrete 20 Up to 60 Plastic 12 Up to 19 Rubber 9 Up to 20 Bentonite 8 Up to 20 The survey results also indicated that a pit is typically designed to extend 1.5 m to 3.0 m (approximately 5 ft to 10 ft) beyond the edge of the tank in order to capture a majority of the leaking oil. The use of alarms and monitoring practices was also surveyed in 1992. Only 14 of the responding utilities (24%) monitored the discharge point, and nine utilities (15%) employed alarms at the discharge point. C.2 2012 IEEE survey A survey was issued in 2012 to update the 1992 survey and document any changes in oil containment methods and practices. Response to the survey was limited, and very few responses were complete, so most of the questions had far less than the total 26 responses. The questions in the survey along with a summary of the responses follow. C.3 General information Q1: How many sub/switching stations exist on your system? Responses varied from two to 1700. Q2: At these stations, how many spill events have you had in the last 10 years? Responses varied from zero to 379 with five responses in the 25 to 50 range. Other responses were none that reached waters of the United States; two or three significant spills; approximately 100, most minor in nature; two or three significant spills. Q3: Of these spills how many extended outside the property boundaries? Reponses varied from none to 10 with many responding “none.” C.4 Sources of spills Q4: Of your fluid-filled equipment, approximately what percentage of equipment is filled with the following? Mineral oil: Responses varied from 95% to 100% with most responses at 100%. 73 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Alternative fluids: Responses varied from 0% to 5% with most responses at 0%. Q5: Approximately what percent of the following sources is the cause of your spills? Equipment failure: Responses varied from 50% to 100% with the average at 85%. Vandalism: Responses varied from 0% to 50% with the average at 13%. Human error: Responses varied from 0% to 10% with the average at 6.5%. Other (please explain in comments at end of survey): Responses varied from 0% to 45% with the average at 8%. Comments were lacking to explain the other causes. Q6: For which of the following devices do you provide secondary oil containment and/or diversionary structures to prevent discharged oil from exiting the station (e.g., berms, oil containment pits, drainage through oil/water separators)? Also, please indicate the typical breakpoint in voltage, MVA, etc. (examples: for transformers―10 MVA and above, for breakers―138 kV and above) for that type of equipment where your company deems the quantity of oil in the device high enough to warrant secondary containment. If not used, this question is not applicable. Note—Secondary oil containment = a system designed to contain the oil discharged from an oil-filled piece of equipment in situations of primary oil containment failure. Power transformers: Responses were 69 kV or greater, 189 L (50 gal) or more of oil; in new subs and highrisk subs; nearly all; approximately 80%; all; 10 MVA and above. Oil circuit breakers: Responses were 138 kV or greater, 189 L (50 gal) or more of oil; nearly all; 69 kV and higher; high-risk subs; we retrofit containment around OCBs where they are next to underdrains, adjacent to fence lines, etc.; three respondents said “no.” Shunt reactors: Responses were 100 MVA or greater, 189 L (50 gal) or more of oil; nearly all; three responded “all”; one responded “no.” Oil-filled cables (including terminal stations): Responses were 138 kV or greater; double wall tank at terminal stations; full secondary containment for tanks, NA for pipeline; nearly all; 138 kV or greater; no containment on cables themselves, but we do provide secondary containment on pumping stations; four responded “no.” Three-phase regulators: Responses were nearly all; all; one “yes” response; one “no” response; pit, trench/ moat; oil containment pits. Single-phase regulators: Responses were in new subs and high-risk subs; gravel bed; oil containment pits; nearly all; all; one “yes” response and one “no” response. Mobile transformers: Responses were 69 kV or greater, 189 L (50 gal) or more of oil; nearly all; secondary containment; berm, pit, gravel bed; one “none” response, one “no” response and one “yes” response. Mobile breakers: Responses were berm, pit, gravel bed; nearly all; two “no” responses. Mobile regulators: Responses were berm, pit, gravel bed; nearly all; all; one “yes” and one “no” response. Mobile substations: Responses were berm, pit, gravel bed; nearly all; all; 100%; one “yes” and two “no” responses and one “none” response. 74 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Oil filling/transporting equipment: Responses were 69 kV or greater, 189 L (50 gal) or more of oil; bermed truck unloading area; berms, pop-up containment, drip pans, absorbent materials, tools for building berms; usually parked empty. When in use, substation surface area is sufficient. If parked full, then parked in lot with secondary containment; nearly all; all; none; 100%; two “no” responses. Station service transformers: Responses were gravel bed; generally small and use slagged surface area of substation. If inside, oil-stop is used in drains; nearly all are generally contained; 30%; four “no” responses. Potential transformers: Responses were trench/moat, gravel bed; in high-risk subs; generally small and use slagged surface area of substation; nearly all; only if positioned in water retention areas; rarely, but we may provide drainage controls if underdrains are adjacent to PTs; three “no” responses. Current transformers: Responses were trench/moat, gravel bed; generally small and use slagged surface area of substation; nearly all; rarely, but we will provide drainage controls if underdrains are adjacent to CTs; five “no” responses. Oil circuit reclosers: Responses were gravel bed; nearly all; three “no” responses. Capacitor banks: Responses were gravel bed; generally small and use slagged surface area of substation; nearly all; five “no” responses. Aboveground oil storage tanks: Responses were secondary containment; double wall; four “all” responses; two “yes” responses. Below-ground oil storage tanks: Responses were leak detection; double-walled fiberglass; all are double wall; 60%; yes, all USTs have double-walled; one “no” response. Q7: Which of the following criteria determines whether secondary containment is required at your substations? Please describe the criteria numerically in the third column (e.g., >3785 L (1000 gal), ≤ 152 m (500 ft) from water). Volume of oil in individual device: Responses were greater than 189 L (50 gal); 189 L (50 gal); ranked 1 to 5 from < 1893 L (500 gal) to > 37 854 L (10 000 gal); all transformers, OCBs, regulators; >208 L (55 gal) but depends on location within sub; >1893 L (500 gal). Proximity to navigable waters: Responses were less than 305 m (1000 ft); <30.5 m (100 ft) from drain or surface water; ranked 1 to 5 from > 762 m (2500 ft) to < 30.5 m (100 ft); less than 305 m (1000 ft); “yes”; drainage to water; management decision; “yes,” within 61 m (200 ft) of navigable waters. Location of substation (urban, rural, etc.): Responses were less than 305 m (1000 ft); proximity to residential or commercial customers; ranked 1 to 5 from rural to urban; impact to navigable water; “no” (two responses); all; “yes,” proximity to sensitive environmental receptors. Potential contamination of groundwater: Responses were “yes” (four responses); all; impact to navigable water. Age of station or equipment: Responses were “no” (three responses); “yes”; all. Emergency response time if a spill occurs: Responses were “no”; “yes” (three responses); ranked 1 to 5 from < 8 km (5 mi) to > 64 km (40 mi); one site 4 h from service territory (wind farm); impact to navigable water. Failure probability of the equipment: Responses were “no” (two responses); “yes”: all; assume 100% failure; “yes,” primarily power transformers versus OCBs and other oil-filled equipment; 75 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Soil characteristics at and near the station: Responses were “no” (two responses); “yes” (two responses); determines if a lined pit is used; impact to navigable water. Laws and regulations: Responses were “yes” (five responses); EPA regulations and guidance and company policy; impact to navigable water. Cost of containment versus cost of cleanup: Responses were “yes”; “no” (three responses). Software analysis: Responses were in some substations; “no” (two responses); use risk modeling software; by consultant only. Other: Responses were rankings affected by presence or not of SCADA system and whether (in case of customer subs) or no personnel are onsite 24 h/day; substations do not require secondary containment. Q8: Which of the following secondary oil spill containment methods have been used in your stations? Open oil retention pit: Responses were new installations, effective (six responses); new installations; retrofit installations, effective (three responses); retrofit installations. Fire-quenching and oil retention pit: Responses were new installations, effective (four responses); new installations (three responses); retrofit installations, effective (four responses). Gravity separator: Responses were new installations, effective; new installations; retrofit installations, effective; retrofit installations. Oil–water separator: Responses were new installations, effective (four responses); new installations (two responses); retrofit installations, effective (four responses); retrofit installations. Oil trap: Responses were new installations, effective (two responses); new installations; retrofit installations, effective; retrofit installations. Oil-absorbing polymer beads: Responses were new installations, effective (three responses); new installations (two responses); retrofit installations, effective (four responses); retrofit installations (three responses). Perimeter or equipment berm: Responses were new installations, effective (two responses); new installations (two responses); retrofit installations, effective (six responses); retrofit installations (three responses). Oil detection-triggered sump pump: Responses were new installations, effective (two responses); new installations; retrofit installations, effective (two responses); retrofit installations (two responses). Oil–water stop valve: Responses were new installations, effective (two responses); new installations; retrofit installations, effective; retrofit installations (three responses). Other (please describe): Responses were new installations, effective (three responses); retrofit installations, effective (three responses); retrofit installations; use CI agent bags to stopper drains in housed substations to allow water to pass, but will solidify upon oil contact. Comments: Two systems currently used are oil-absorbing beads and oil/water separators. Both systems employ berms and pits/ponds; oil-absorbing media used only in and around drains inside substations; petro pipe; for substations reviewed by risk modeling software, low-risk no general containment; fire-quenching and oil retention pilot project under way. Many challenges to overcome, specifically the ability for vehicles to travel over surface material #5 stone; for those retro-fit installations, I have not checked “effective” on oil-absorbing beads or the stop valve because we are just now installing these products and cannot comment 76 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations yet. Oil detection-triggered sumps seem to work well but are high maintenance devices. We did have one fail and actually pump oil; however, this seems to have been an anomaly and has not happened again. Many oil traps and separators, in our system, were not designed properly and could become overwhelmed with oil in the event of a large spill or could allow sheen through due to turbulence; have used system, which has firequenching stone that has oil-absorbent powder in mats; voids in surface crushed rock. Q9: If oil retention pits under large equipment such as transformers and oil filled circuit breakers are used: What percent of the tank’s oil volume is the pit designed to retain? What reason or criteria is the selected percentage based on? Responses were 100%; 120%; 100% plus 25 year, 24 h maximum rain event (inches) per EPA guidance; 100% to 110%. Even though “general secondary containment” is warranted, we still size or oversize the pits; 100% plus 100 year rainfall event; 100% plus 100 year rainfall event; 110% + freeboard; 100% plus 6” for rain water allowance; 150% for new installations, oil plus rain runoff; 110% on average (rule of thumb criteria we have used as substitute for 25 year, 24 h storm). Do you include rainwater and/or water from the fire protection systems in sizing of spill containments and if so how much? Responses were “yes” plus 100 year, 24 h storm; 110% + 15.24 cm (6 in) of freeboard; “yes,” 20%; generally 10% extra volume; used when justifying size of O/W separator; “yes,” 25 year, 24 h storm event; 100% plus 15.24 cm (6 in) for rain water allowance; 50% freeboard; “yes,” 110% on average (rule of thumb criteria we have used as substitute for 25 year, 24 h storm); yes, 25 year rain event. For transformers, how far beyond the edge of the tank/radiators does the pit normally extend? Responses were 3 m (10 ft) skirt around equipment foundation; 1 m (3 ft) minimum, may be greater; far enough to contain any vertical leaks; varies; typically 3 m (10 ft); varies, at least 0.61 m (2 ft); minimum half the height of the oil tank; for new installs, at least 3 m to 4.5 m (10 ft to 15 ft); depends on volume required and site. Not designing for a spray from a puncture. For oil-filled breakers, how far beyond the edge of the tank does the pit normally extend? Responses were 1 m (3 ft) minimum, may be greater; 1 m (3 ft) or more (varies); varies, at least 0.61 m (2 ft); 1.2 m to 1.5 m (4 ft to 5 ft). Do you evaluate the soil characteristics to determine if the pit should be lined? Responses were consultant considers; “yes” (four responses); “no” (two responses); “no,” all pits are lined. If yes, what soil characteristic criteria are used to determine if a lining is necessary? Responses were up to consultant to decide; permeability; percolation rates (specific value not available at this time); effectively impervious clays (10^-3 cm/s hydraulic conductivity); always line. Q10: Where an impervious material is used to line the pit, what material is used? Rubber liner: Responses were used, new designs (three responses), retrofit designs, effective. Plastic liner: Responses were new designs (two responses); retrofit designs, effective (two responses). Geo-membrane liner: Responses were used, new designs (seven responses); retrofit designs, effective (four responses). Spray-on liner: Responses were used, new designs (three responses); retrofit designs, effective (two responses) Clay (bentonite): Responses were used (four responses), new designs (two responses); retrofit designs, effective (two responses); retrofit designs. 77 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Concrete: Responses were used; used, new designs (eight responses); retrofit designs (two responses); effective (five responses). Other (please specify): Responses were used in new designs and retrofit designs; used; see comments. Comments: Responses were cinder block containment wall lined with rubber liner; flex-base (crushed limestone compacted to 95% standard proctor); concrete cracked in a pit and had to be excavated 5 ft under the concrete to remove contaminated soil―sandy soil that percolated very well; for other, we are starting to install CI agent systems for retrofits. Q11: Do you fill containment pits with crushed rock or stone for fire suppression? If yes, what values are typically used for the following: Design depth below the rock/stone surface the level of oil will reach to ensure fire quenching will be successful? Responses were not a consideration; “no”; 1 m (3 ft); “yes”; varies; 15.24 cm (6 in); according to EPRI study we had conducted, oil must be 30.48 cm (12 in) below slag surface to provide sufficient fire quenching. This is based on #2 Duquesne slag; 5.08 cm (2 in) depth of 2.54 cm (1 in) diameter rock, not designed for suppression; not sure. Pits are allowed to fill most of the way. Design void ratio for oil containment volume? Responses were 40% (six responses); 30% to 40%; depends on the rock size, for 2.54 cm (1 in) river rock, 30% void is used. Clean up and control Q12: Which of the following oil spill cleanup methods do you employ? River boom deflector: Responses were used, effective (five responses). Straw skimming: Responses were used, effective. Expanded straw skimming: Responses were used, effective. Lake boom deflector: Responses were used. effective (two responses). Berm cleanup: Responses were used, effective (six responses). Dike on sloped ground: Responses were used, effective (four responses). Stone vacuum truck: Responses were used, effective (six responses); used (two responses). Soil removal: Responses were used, effective (10 responses); used (three responses). Other (please describe): Responses were used, effective (three responses). See comments. Comments: Responses were sorbents, oil dry oil booms; adsorbents, absorbents, underflow dams; soil removal takes place after all foundation/concrete is cleaned of oil; removal of contaminated rock, soil; most spills are small enough that soil/stone excavation is all that is needed. 78 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations Annex D (informative) Bibliography Bibliographical references are resources that provide additional or helpful material but do not need to be understood or used to implement this standard. Reference to these resources is made for informational use only. [B1] American Concrete Institute, ACI 350, Code Requirements for Environmental Engineering Concrete Structures.10 [B2] American Concrete Institute, ACI 350.1, Specification for Tightness Testing of Environmental Engineering Concrete Containment Structures. [B3] American Society of Mechanical Engineers, ASME B31.3, Process Piping Code.11 [B4] Electric Power Research Institute, EPRI-FP-1, 207, Disposal of PCBs and PCB-Contaminated Materials, 1979.12 [B5] Geosynthetic Research Institute, GRI-GCL5, Standard Guide for Design Considerations for Geosynthetic Clay Liners (GCLs) in Various Applications.13 [B6] IEEE Std 80™, IEEE Guide for Safety in AC Substation Grounding.14,15 [B7] IEEE Std 979™, IEEE Guide for Substation Fire Protection. [B8] IEEE Std 1127™, IEEE Guide for the Design, Construction, and Operation of Electric Power Substations for Community Acceptance and Environmental Compatibility. [B9] IEEE Std C57.12.00™, IEEE Standard for General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers. [B10] Lee, C. C., Environmental Engineering Dictionary, 2nd Ed., 1992.16 [B11] NFPA 850, Recommended Practice for Fire Protection for Electric Generating Plants and High Voltage Direct Current Converter Stations.17 [B12] U.S. Code of Federal Regulations, Title 40 (40 CFR), Toxic Substances Control Act, Part 761, for PCB oils (above 500 ppm) and PCB-contaminated (50–500 ppm) oils.18 [B13] U.S. Department of Agriculture, REA Bulletin 65–3, 1981, Design Guide for Oil Spill Prevention and Control at Substations.19 This document is available from the American Concrete Institute (https://www.concrete.org/). This document is available from the American Society of Mechanical Engineers (https://www.asme.org). 12 This document is available from the Electric Power Research Institute (https://www.epri.com/Pages/Default.aspx). 13 This document available at http://www.geosynthetic-institute.org/grispecs/gcl5.pdf. 14 IEEE publications are available from The Institute of Electrical and Electronics Engineers (https://standards.ieee.org/). 15 The IEEE standards or products referred to in this clause are trademarks of The Institute of Electrical and Electronics Engineers, Inc. 16 This document is available from the Government Institutes, Inc., Rockville, MD 20850. 17 NFPA publications are published by the National Fire Protection Association (https://www.nfpa.org/). 18 CFR publications are available from the U.S. Government Printing Office (https://www.gpo.gov/). 19 U.S. Department of Agriculture documents are available https://www.usda.gov/wps/portal/usda/usdahome/. 10 11 79 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. IEEE Std 980-2021 IEEE Guide for Containment and Control of Oil Spills in Substations [B14] U.S. Department of Agriculture, Rural Development Utilities Programs, Bulletin 1724E–302, Design Guide for Oil Spill Prevention and Control at Substations, January 14, 2008.20 20 This document available at https://www.rurdev.usda.gov/SupportDocuments/UEP_Bulletin_1724E-302.pdf. 80 © 2022 IEEE. Allonrights reserved. Authorized licensed use limited to: Universidad IndustrialCopyright de Santander. Downloaded March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply. RAISING THE WORLD’S STANDARDS Connect with us on: Twitter: twitter.com/ieeesa Facebook: facebook.com/ieeesa LinkedIn: linkedin.com/groups/1791118 Beyond Standards blog: beyondstandards.ieee.org YouTube: youtube.com/ieeesa standards.ieee.org Phone: +1 732 981 0060 Authorized licensed use limited to: Universidad Industrial de Santander. Downloaded on March 27,2026 at 20:59:22 UTC from IEEE Xplore. Restrictions apply.

IEEE Std 980-2021: Oil Spill Containment Guide for Substations

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