Guidance for Treatment of Airport Stormwater Containing Deicers (2013)

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1 1.1 Background To support safe operations, airport operators and tenants apply a variety of deicing and anti-icing chemicals (collectively called deicers) to aircraft and to airport paved surfaces. The mixed flows containing applied deicers and stormwater runoff must often be managed to mitigate potential envi- ronmental impacts to surface water and groundwater. The comprehensive, integrated systems for collecting, conveying, monitoring, storing, treating, and discharging stormwater affected by deicing are often called deicer management systems (Figure 1). Deicer treatment is the component of a deicer management system that removes contaminants of concern from stormwater. Since the mid-1980s, the aviation industry has implemented various deicer treatment technolo- gies. Based on changing airport infrastructure, flight operations, weather patterns, and regulatory compliance needs, implementation of new and enhanced deicer treatment systems is likely to be needed in the foreseeable future. 1.2 Guidebook Purpose and Value to Aviation Industry This guidebook is intended to provide the aviation industry with a reference to facilitate the implementation of deicer treatment technologies at individual airports. In gathering the infor- mation for its content, the research team assessed a wide cross section of airports representing many different deicer treatment approaches in the United States, Canada, and Europe. The first objective of the research was to accurately document the deicer treatment technologies that have been applied. Those efforts yielded a better understanding of deicer treatment technology performance and provided numerous lessons learned regarding applicability, performance, cost, and operational considerations. These in-the-field experiences were melded with theoretical understanding of deicer treatment and consolidated in this guidebook. The guidebook can be used to help frame the deicer treatment component of the overall deicer management system implementation process for individual airports. In practice, however, use of the guidebook must be coupled with consideration of site-specific factors such as storm- water characteristics, permit limits, site infrastructure constraints, airport operational impacts, and costs. Appropriate implementation of a deicer treatment system must be supplemented by engaged management of the treatment system by airport operators. Deicer treatment is often a unique C H A P T E R 1 Introduction Deicer Treatment Technologies Featured in the Guidebook Activated sludge Aerated gravel beds Aerated lagoons Anaerobic fluidized bed reactors Distillation Mechanical vapor recompression Moving bed biofilm reactors Passive facultative technologies Private off-site recycling systems Public wastewater treatment systems Reverse osmosis

2 Guidance for Treatment of Airport Stormwater Containing Deicers operation for airports and in many ways is a foreign experience. It is also an operation that can be highly dynamic because of real-time dependencies on weather and airport operations. Inadequate management of deicer treatment operations can increase the risk of noncompliance and lead to excessive costs for even the most well-designed treatment system. The need for a guidebook on deicer treatment is driven by several factors: • An effective and reliable means of deicer treatment is critical to regulatory compliance. • Improper selection, design, and management of deicer treatment systems can have significant short-term and long-term cost implications. • Existing guidance on sizing, effectiveness, and costs of treatment technologies that is derived from treatment of other waters is not always appropriate to treatment of stormwater affected by deicer. • The experiences and performance data on deicer treatment at individual airports have not been previously transmitted to the aviation industry in a collective manner. It is envisioned that the aviation industry will find the following guidebook contents of value: • Summaries of airport deicer treatment experiences. The airport summaries in this guidebook provide insight from the real-world experiences of airport operators. Critical Actions for Engaged Management of Deicer Treatment Systems 1. Provide appropriate operational oversight 2. Facilitate timely maintenance 3. Understand treatment system limitations 4. Be attentive to treatment system needs 5. Coordinate treatment decisions with overall deicer management system operation Figure 1. Schematic of potential deicer management system components. Reuse, Off-Site Sale, or Disposal Airfield Operations Apply Deicers to Aircraft/Paved Surfaces Discharge to Receiving Water Monitor Runoff for Compliance and Management Conveyance to Treatment Deicer Treatment Storage Stormwater Infrastructure Treated Effluent B y- pr od uc ts (gl yc ol, so lid s, m et ha ne ) Aircraft Operations Weather R unoff below collection criteria R unoff ex ceeds collection criteria Monitoring and Flow ControlPretreatment

Introduction 3 • Treatment technology fact sheets. Fact sheets for 11 deicer treatment technologies provide concise summaries of the function, features, and application of treatment technologies that have been applied at airports to help inform the technology implementation process. • Description of the information needed to establish a basis for selecting and designing treatment. The guidebook discusses the types of information typically required to establish a basis for treatment technology selection and design. • Graphical relationships of technology cost and capacity. The guidebook presents relationships between the quantities to be treated (pollutant mass loads) and order-of-magnitude capital and operational costs for 11 treatment technologies. • Methodologies for selecting one or more deicer treatment technologies. Potential methodologies that can be used to help select treatment technologies are presented. • Insight on techniques for treatment technology design, construction, and operation. The guidebook distills the collected experiences of the research team and aviation industry into guidance for designing, constructing, operating, and maintaining deicer treatment systems. 1.3 Guidebook Approach to Deicer Treatment Implementation The guidebook provides a representation of the process an airport may follow for imple- mentation of a deicer treatment system. It provides recommendations on methodologies to follow and on information frequently sought by those considering new or modified treatment systems. In practice, the deicer treatment implementation process is customized to the individual situ- ations and is often iterative in nature. The needs for site-specific information and assessment of technology applicability to the site go well beyond what is contained in this guidebook. The guidebook can, however, provide a framework and reference to help make the processes imple- mented at individual airports more effective and efficient. For many airports, the processes for implementing deicer treatment and the remainder of the deicer management system run in parallel. The scope of this guidebook is focused on deicer treatment. However, because of the link between deicer treatment and the entire deicer management system, other deicer management system elements are referenced throughout the guidebook when there is a significant relationship to deicer treatment. Recommended Process for Implementing Deicer Treatment 1. Establish the regulatory compliance drivers for treatment system implementation. 2. Characterize the stormwater to be treated. 3. Determine site and operational constraints for treatment implementation. 4. Identify potential deicer treatment technologies. 5. Perform technical and cost assessments to select the deicer treatment technologies. 6. Design and construct the treatment system as part of the overall deicer manage- ment system. 7. Actively manage the implemented treatment system.

4 Guidance for Treatment of Airport Stormwater Containing Deicers 1.4 Guidebook Structure As shown in Table 1, the guidebook contains six chapters, with Chapters 2 through 6 represent- ing steps in the process for approaching deicer treatment implementation. The emphasis of the appendices is on providing information on technology capabilities and application experiences. Chapter 1: Introduction Establishes the need, value, and use of the guidebook and provides general information on the current state of deicer treatment. Chapter 2: Defining Deicer Treatment Needs and Implementation Constraints An airport that requires new or enhanced deicer treatment must first define the need, objectives, and basis for the treatment technology selection and design. Chapter 2 discusses the characteriza- tion of regulatory constraints, stormwater to be treated, airport site features, and airport operational features that are required to establish the basis for treatment technology selection and design. Chapter 3: Identifying Deicer Treatment Technologies Chapter 3 presents information that categorizes and characterizes the deicer treatment technologies that have been applied in the industry. Chapter 4: Selecting Deicing Treatment Technologies Chapter 4 describes methodologies that airports can use to help select the specific treatment technology or technologies to be implemented. The elements of the recommended selection process include: • Screening out technologies that are not feasible, and • Comparative analysis of technologies based on consideration of site-specific criteria. Chapter 5: Designing and Implementing Deicer Treatment Systems Chapter 5 provides guidance, considerations, and lessons learned for the design, construction, and management of the deicer treatment systems in the context of the entire deicer management system. Subject Location Guidance on Methodologies for Technology Selection and Implementation • Introduction • Defining deicer treatment needs and implementation constraints • Identifying deicer treatment technology alternatives • Selecting deicer treatment technologies • Designing, constructing, and managing deicer treatment systems • Determining costs for deicer treatment Main Guidebook Text Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Information on Individual Technology Characteristics and Capabilities • Treatment technology use listed by airport • Treatment technology characteristic matrix • Instructions for using treatment technology fact sheets • Airport treatment system summaries Guidebook Appendices Appendix A Appendix B Appendix C Appendix D Table 1. Guidebook structure.

Introduction 5 Chapter 6: Determining Costs for Deicer Treatment Chapter 6 provides guidance on determining costs for deicer treatment at various stages of implementation and cost considerations for various treatment technology categories. Appendices Appendix A provides a list of 106 airports and the deicer treatment technologies that they use. Appendix B provides a matrix of deicer treat- ment technologies and the parameters that are important to the treat- ment technology selection process. Appendix C contains instructions for using treatment technology fact sheets for the 11 types of technologies referenced in this guidebook. Appendix D summarizes how 15 selected airports from the United States, Canada, and Europe manage deicer treatment. The featured airport systems were selected to provide a broad representation of in-the-field performance of the technologies in the fact sheets. The types of information presented in the technology fact sheets and airport summaries are listed in the Deicer Treatment Technology Fact Sheet Contents and Airport Deicer Treatment System Summary Contents text boxes. Throughout the guidebook, text boxes: • Summarize key points from the guidebook text, • Illustrate how specific airports have used deicer treatment, and • Provide treatment tips, which are lessons learned and guidance on specific technical aspects of deicer treatment. 1.5 Deicer Treatment Terminology Based on feedback from the aviation industry during research for this guidebook, it is apparent that inconsistent use of deicer-treatment–related terminology can impede the technology’s effective implementation. It is recommended that the stakeholders executing deicer treatment system implementation coordinate on defining a common understanding of treatment-related terms that will be used throughout the process. To help facilitate the use of consistent terminology, newly used terms in the guidebook are presented in italics. A full list of terms can found in the Glossary. Several key terms used in the guidebook are defined in the following. Deicer Treatment Technology: Treatment technology is used in this guidebook to refer to a specific physical, chemical, or biological process whose primary purpose is removal of the pri- mary deicer constituents from stormwater. In this guidebook, treatment technology categories include biological-based treatment systems located at airports, recycling-based systems located at airports, and off-site systems like publicly owned treatment works (POTWs) and privately run recycling operations. A primary goal of each category of treatment technology is the removal of primary deicer constituents from the stormwater that will ultimately be discharged to surface waters. Deicer Treatment System: Deicer treatment systems are an integrated set of treatment tech- nologies and support processes that are designed to work together to remove or degrade primary deicer constituents from airport stormwater runoff at a specific airport. The distinction between the terms treatment technology and treatment system is important in this guidebook. A treatment Deicer Treatment Technology Fact Sheet Contents Process description Advantages Disadvantages Required support systems Current airport applications Potential applications Critical parameters for success Order-of-magnitude costs Airport Deicer Treatment System Summary Contents Treatment technology category Years operated Deicer management system description Technology selection considerations Deicer treatment technology description Treatment system performance Cost assessment Conclusions on performance Lessons learned

6 Guidance for Treatment of Airport Stormwater Containing Deicers technology is a specific means for processing deicer whose essential elements can be applied to multiple airports. A treatment system is designed to operate at a specific airport. A treatment system can include one or more treatment technologies sized to the needs of the airport, plus the technology’s required support systems (e.g., supporting processes that include piping, containment vessels, mechanical and electrical components, and instrumentation). Head-to-head comparisons of treatment system performance and cost among airports is often not of the apples-to-apples variety, even if the airports are using the same technology, because of the site-specific differences in stormwater characteristics, system capacity, and operating scheme. For the purposes of this document, a deicer treatment system is a subset of the broader term stormwater treatment system. A stormwater treatment system can be any system or combination of technologies used to improve stormwater quality. Many controls and best management practices (BMPs) for treating constituents in typical airport stormwater runoff are not effective for treating deicers. Many deicer treatment technologies are not designed to treat contaminants such as oil and grease, sediment, and metals. On-Site Deicer Treatment System: In this guidebook, an on-site deicer treatment system is a system that is located at or near an airport and is under the direct control of the operator of the airport. The primary function of an on-site deicer treatment system is the degradation, reduction, or recycling of primary deicer constituents in that airport’s stormwater runoff. Direct control could include operation by airport staff or operation by outside firms contracted by the operator of the airport. Off-Site Deicer Treatment System: In this guidebook, an off-site deicer treatment system is one located off of the airport site that is under the direct control of a non-airport entity and is designed to process wastewaters of multiple types or from multiple sources. Examples of off-site deicer treatment systems are: • Municipal wastewater treatment plants (WWTPs, also known as POTWs), • Privately owned wastewater treatment facilities, and • Privately owned facilities that reclaim/recycle deicing chemical contained in stormwater. Primary Deicer Constituents: In this guidebook, the term primary deicer constituent means the freezing-point–depressant chemicals in deicers that are the primary contributors to potential water quality issues. These includes propylene glycol, ethylene glycol, glycerin, acetate, formate, and urea. Design Performance: The design performance of a treatment system is its treatment and processing capabilities as described in the system’s basis of design. Some may refer to this as a “theoretical performance.” As a subset of design performance, the term design capacity refers to the maximum flow rate of stormwater or mass loading rate of stormwater pollutants that can be processed by a deicer treatment system based on conditions in a projected design year or design circumstance. The design capacity serves as the basis for the sizing and design of the treatment facilities. Actual Performance: Actual performance is the demonstrated performance of a deicer treatment system as calculated using analytical and process data collected during system operation. A variety of parameters can be used to describe design and actual performance, including: • Ability to achieve design capacity. The ability of a treatment system to demonstrate successful operation at or above its design flow rate or mass loading rates is a common measure of performance. Treatment systems are often sized to have capacity for a future deicing condition to accommodate potential airport operations growth. • Treatment efficiency. Many airport operators calculate the treatment efficiency (also known as removal efficiency) as the percentage of influent pollutant mass load that is removed during

Introduction 7 treatment. Treatment efficiency may be expressed for any specific pollutant. This serves as a long-term measure of the performance consistency. Treatment efficiency can be calculated from the following equation: Treatment Efficiency = (Influent Mass Load – Effluent Mass Load)/(Influent Mass Load) • Pollutant effluent concentrations or effluent quality. The ability of a treatment system to generate effluent at or below its design concentration targets for pollutant parameters such as bio- chemical oxygen demand (BOD), chemical oxygen demand (COD), total organic carbon (TOC), propylene glycol (PG), or ethylene glycol (EG) is frequently used as a measure of performance. (Refer to Section 2.2 for definition and discussion of specific pollutant parameters.) • By-product concentrations and quantities. The effectiveness of deicer recycling systems, in par- ticular, is judged in part by the magnitude of the concentrated glycol concentration and the quantities of recycled product that can be reclaimed. For some biological treatment systems, the quantity of off-gas that can be captured and used for fuel is also used to assess performance. The quantity of biological solids that need to be disposed of is also a performance indicator. • Cost performance. Both capital and operating/maintenance costs are important parameters in judging the performance of a treatment system. 1.6 Current Deicer Treatment Technology Applications The research effort for this guidebook included collecting, assessing, and consolidating the experiences of those airports that have implemented deicer treatment systems. The research team gathered information from 106 airports that use deicer treatment technologies. The 106 airports are distributed throughout the United States, Canada, and Europe. The information was gathered from existing publicly available information, site visits to airports, phone discus- sions, and research team experience. A total of 155 deicer treatment technology applications were identified at 106 airports. The 155 technology applications and the 106 airports provide a large sampling of the technologies that have been applied, but do not represent all of the deicer treatment applications at all airports. From an evaluation of the 155 treatment applications, the research team identified 11 basic categories of deicer treatment technologies for inclusion in this guidebook. The primary criteria for inclusion of a technology in the list were: • The technology has been applied to treat deicer-affected runoff in a full-scale system. • The technology has characteristics that are reasonably distinct from other technologies in the list. Some closely related technologies were grouped into a single technology category. • There has been enough experience with using the technology to make supportable conclusions regarding its applicability and effectiveness for deicer treatment. Figure 2 illustrates the range of deicer treatment technology applications based on the information gathered in this research. As shown, approximately two-thirds of the technology applications involve treatment that is not on the airport site and not under airport control. This includes discharges to POTWs or recycling of deicer at private facilities not owned by the airport or municipality. As shown in Figure 3, approximately one-third of airports use more than one technology. Almost 50% of the airports that discharge to a POTW also have some type of on-site treatment. Figure 4 through Figure 7 show the distribution in the United States of the deicer treatment methods discussed in this guidebook: on-site biological, on-site physical treatment (generally recycling), off-site biological treatment (generally POTWs), and off-site physical treatment (generally recycling). Please refer to Appendix A for a complete list of the airports represented in these graphics. The individual treatment technologies are discussed in more detail in Chapter 2.

8 Guidance for Treatment of Airport Stormwater Containing Deicers Public Wastewater Treatment Facilities, 45% Private Recycling Facilities, 19% Aerated Gravel Bed Treatment, 3% Moving Bed Biofilm Reactor, 1% Activated Sludge, 1% Aerated Lagoon, 5% Anaerobic Fluidized Bed Reactor, 3% Passive Facultative Treatment, 5% Distillation, 3% Vapor Recompression, 11% Reverse Osmosis, 5% Figure 2. Deicer treatment technology use in assessed airports. Airports Using Multiple Treatment Technologies, 34% Airports Using a Single Treatment Technology, 66% Figure 3. Airports using more than one treatment technology.

Introduction 9 Figure 4. U.S. airports using off-site biological treatment technologies. Figure 5. U.S. airports using off-site recycling technologies.

10 Guidance for Treatment of Airport Stormwater Containing Deicers Figure 6. U.S. airports using on-site biological treatment technologies. Figure 7. U.S. airports using on-site physical treatment technologies for recycling.