Practices for Project-Level Analyses for Air Quality (2021)

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6 Introduction The literature review for this study was designed to uncover and describe studies and reports that would be of maximum value to DOT air quality practitioners. In other words, information was identified that could be used by air quality practitioners to • Apply federal or state guidance or regulations in an effective and thorough manner, • Streamline or simplify project-level air quality studies, • Address issues that could assist them in dealing with select air quality topics, • Obtain particularly complete and comprehensive examples of dealing with one or more pollutants typically encountered by DOTs, and • Identify gaps in addressing project-level air quality issues that could be resolved by additional guidance or research. This literature review does not include a detailed review and discussion of applicable federal guidance or regulations, whether from U.S. EPA or FHWA. These are sufficiently publicized and summarized by the cognizant agencies and are generally familiar to DOT air quality practitioners. For example, the most frequently used guidance includes the following: • For modeling CO hot spots – “Guideline for Modeling Carbon Monoxide from Roadway Intersections” (U.S. EPA, November, 1992), and “Using MOVES2014 in Project-Level Carbon Monoxide Analyses” (U.S. EPA, March 2015). • FHWA’s categorical finding – “Updated Carbon Monoxide Categorical Hot-Spot Finding Memo” (FHWA, July 2017). • For modeling PM10 and PM2.5 hot spots – “Transportation Conformity Guidance for Quanti- tative Hot-Spot Analyses in PM2.5 and PM10 Nonattainment and Maintenance Areas” (U.S. EPA, November 2015). • For modeling hot spots in California using the EMission FACtor model (EMFAC) – EMFAC2017, Volume II, Handbook for Project-Level Analyses (California Air Resources Board, March 2018). • For MSAT analysis – “Updated Interim Guidance on Mobile Source Air Toxic Analysis in NEPA Documents” (FHWA, October 2016). Instead, the review looked for information that could be used by DOTs to make their project- level air quality analyses more technically sound, more comprehensive, more cost-efficient, and more informative to decision makers and the public. NCHRP has a long history of research related to transportation air quality and provides the bulk of the citations for this study’s literature review. This history began in 1993 with the beginning of NCHRP Project 25-06, “Intersection Air Quality Modeling.” Since then, NCHRP has studied transportation air quality topics as diverse as data sources for emission estimates (NCHRP Project 25-07: “Improving Transportation Data for Mobile Source Emissions Estimates”), implementing the Clean Air Act Amendments (NCHRP C H A P T E R 2 Literature Review

Literature Review 7   Project 20-07/Task 060: “Support for Implementing the Clean Air Act Amendments of 1990”), traffic flow projects (NCHRP Project 25-21 and NCHRP Report 535: Predicting Air Quality Effects of Traffic-Flow Improvements: Final Report and User’s Guide), and assistance in implementing new air quality standards (NCHRP Project 25-25/Task 06: “Preparing State DOTs for Implemen- tation of the 8-Hour Ozone and PM2.5 Standards”). NCHRP Studies The NCHRP studies selected for this project are current and relate to air quality topics that DOTs face today. Also included in the literature review are studies from other sources that are particularly designed for air quality practice at DOTs. Quick Reference Guide for Transportation Planners/Engineers: Generating Traffic and Activity Data for Project-Level Air Quality Analyses – NCHRP Project 25-25/Task 96 Final Report This study is a comprehensive and extensive explanation of traffic data needs for estimating emissions for various mobile source pollutants in support of a quantitative project-level air quality analysis. It brings together expertise from traffic modelers and air quality practitioners in order to facilitate communica- tions between the two subject areas. The report addresses traffic needs for project-level analyses for CO, PM, MSATs, and GHGs. It provides detailed tables and color-coded figures to aid practitioners in determining the appropriate traffic parameters for the analysis to be undertaken. For CO, PM, and MSATs, the color coding corresponds to the different steps of the analysis (project assessment, screening analysis, and refined analysis). The tables correspond to similar steps of the analysis and provide information on traffic/activity input, effect on emissions and concentra- tions, possible methods for determining the traffic/activity input, applicability to base and future years, references, and comments with additional relevant infor- mation. For GHG analyses, generalized information is provided, tying back to the appropriate similarities and tools in the CO, PM, and MSAT information. The report also provides information regarding special situations (e.g., project re-evaluations, mitigation measures, and litigation risk). For these situations, examples, strategies, information resources, and items for consid- eration are discussed, as appropriate for each special situation. The appendices to the report contain forms for requesting from traffic analysts traffic information that an air quality practitioner would need for conducting a CO, PM, or MSAT analysis with corresponding examples of how the requested traffic data might be reported back to the air quality practitioner. Programmatic Agreements for Project-Level Air Quality Analyses – NCHRP Project 25-25/Task 78 Final Report This study focused on transportation projects that are typically analyzed by DOTs under NEPA requirements. It considered CO and under what condi- tions of traffic, geometry, and meteorology exceedances of NAAQS might be modeled to occur.

8 Practices for Project-Level Analyses for Air Quality The study examined a number of DOT air quality analysis procedures and the use of air quality programmatic agreements by DOTs. It found that, of the procedures reviewed, there was a wide range of specificity with regard to analysis triggers, detail in modeling inputs, analysis years, meteorology, or other parameters of project-level air quality analysis. Generally, the procedures focused on intersections operating at a level of service (LOS) D or worse. The study found that three states had programmatic agreements specific to air quality. Four project types were modeled for both rural and urban conditions. Those types include intersections, arterials, freeways, and interchanges. These project types are most commonly analyzed for potential air quality impacts by DOTs as part of the environmental review process. The Motor Vehicle Emission Simulator (MOVES) and the California Line Source Model, Version 3 (CALINE3) with queuing from the Highway Capacity Manual (CAL3QHC) were used to model these project types. Conservative assumptions and inputs were used to make the analysis as useful as possible on a nationwide basis. The report includes tables that show under which project conditions (urban/rural, number of lanes, vehicle speeds, and roadway grades) ambient CO standards could not be exceeded for the four project types. The modeling showed that a wide range of project conditions would not exceed CO air quality standards. Using the results of the modeling, templates were developed for an air quality specific program- matic agreement and technical support document (to serve as the technical explanation and back-up for the programmatic agreement). They are intended as guides that DOTs may use to develop similar documents for their states. The templates consider administrative issues (such as time frames for review, procedures for revision, or authority for approval, in addition to specific modeling inputs and assumptions. The report concludes with suggested research topics related to the development of state- specific programmatic agreements and the extension of the work to PM and MSATs. NCHRP Web-Only Document 210: Input Guidelines for Motor Vehicle Emissions Simulator Model, Volume 2: Practitioners’ Handbook: Project Level Inputs This research produced guidelines on methods, procedures, and data sets to develop or obtain transportation-related inputs for MOVES to estimate emissions of criteria pollutants, air toxics, and GHGs. The work was divided into regional and project-level inputs. Volume 2 relates to project-level inputs and contains resource material on developing inputs for a project level of analysis, using the Project Domain/ Scale of MOVES. This scale allows the user to model the emission effects from a group of specific roadway links and/or a single off-network location. It has information on various inputs for MOVES, a description of the input, and U.S. EPA guidance on use of the input. The research analyzes the sensitivity of the inputs in determining emission rates so that DOT practitioners can focus their efforts on data collection that will most seriously affect their analysis. It considered sensitivity for emissions of volatile organic compounds (VOCs), nitrogen oxides (NOx), and PM and found that temperature, speed, age of vehicles, and vehicle miles traveled (VMT) have the most substantial effect on emissions. This volume examines 10 input variables for MOVES that can be impor- tant at the project level, which practitioners may consider using local data, rather than the embedded data assumed in MOVES. It describes each variable, offers alternative sources that are available to replace the embedded data, and

Literature Review 9   discusses challenges the practitioner may encounter in applying local data in MOVES (e.g., state vehicle registration data mapping into the MOVES source types). This report also has an example of how this may be applied by a DOT. It examines a project that contains the intersection of two major arterials, a park-and-ride lot, and a bus terminal. This example has both link-based sources and off-network emission sources. Substantial detail is provided on how the local data can be obtained, processing steps for manipulating MOVES, and the resulting input variables and their formats. Establishing Representative Background Concentrations for Quantitative Hot-Spot Analyses for Particulate Matter – NCHRP Project 25-25/Task 89 Final Report This study was undertaken to help transportation project air quality analysts estimate representative background concentrations for use in PM hot-spot analyses. It presents two acceptable methods for estimating background PM concentrations: the use of nearby air quality monitors, and the use of chemical transport model (CTM) results. The report identifies several air quality monitoring databases with infor- mation on how to access those databases. It also includes information about accessing CTM databases, as well as some caveats regarding the use of those databases for estimating future PM background concentrations. Most, but not all, of the analysis years in the CTM data sets have already passed. Using ambient monitoring data, the report lists and discusses important factors to consider, including • Identifying an appropriate monitor or monitors, • Comparing monitor site characteristics with project characteristics, • Evaluating data completeness and quality, and • Calculating a background concentration, whether from one monitor or by interpolating among more than one monitor. For CTM data, the report contains steps and guidance for calculating a PM background concentration, using either a future CTM-derived concentra- tion for a representative state or local air agency monitor, or CTM-gridded outputs. The report discusses exceptional events in detail. Exceptional events are defined as unusual events that do not result in a NAAQS exceedance, or that result in an exceedance but may have not yet been approved for exclusion by U.S. EPA. Examples of exceptional events include wildfires, firework displays, dust storms, and so forth. The report is careful to distinguish between U.S. EPA- approved exceptional events, which are therefore excluded when determining whether a monitor exceeds an air quality standard, and a research approach to examine high values of PM measure- ments that do not exceed an air quality standard but may result in a high PM background concen- tration. The report suggests examining monitored data that exceed the 95th percentile of monitored values and potential correlation with meteorological and/or air transport events that may have contributed to high PM concentrations. High background concentrations from exceptional event- like occurrences, when added to a transportation project contribution, could result in a PM concentration greater than the applicable NAAQS. The report also contains five case study examples and templates for documenting background concentration determinations and for documenting exceptional-type and air transport events when calculating background concentrations.

10 Practices for Project-Level Analyses for Air Quality Templates for Project-Level Analysis Using MOVES, CAL3QHC/R and AERMOD – NCHRP Project 25-25/Task 71 Final Report The purpose of the study was to develop a project-level air quality technical report template that could be used by DOTs to reduce time and resources spent developing an air quality report, improve the quality and consistency of these reports, and help DOTs meet new modeling requirements. The templates were designed to meet the transportation conformity and NEPA needs of the states. Existing air quality reports and guidance documents were reviewed, and a number of DOTs were contacted for further information. However, at the time of the research, due to the recent releases of U.S. EPA’s PM hot-spot quantitative guidance, MOVES, and the grace period triggered by those releases, none of the DOTs contacted yet had any experience with the PM guidance or MOVES. Numerous examples of CO analyses performed by the states were available. The result of the research, the Project-Level Analysis Template, is focused on the following types of project-level air quality analysis: • CO hot-spot analysis with MOVES2010 and CAL3QHC (screening) or CAL3QHCR (refined). • PM hot-spot analysis (both PM10 and PM2.5) with MOVES2010 and American Meteorological Society/Environmental Protection Agency Regu- latory Model (AERMOD) or CAL3QHCR. It also incorporates short sections related to road dust and air quality impacts, indirect and cumulative impacts, and MSATs. The Project-Level Analysis Template is color coded to identify elements that are • Instructions and guidelines to be deleted from the final document (blue text), • Instructions to be replaced with project-specific text (red text), • Boilerplate text that generally will not need to be modified for each project (black text), and • Sample text that must be modified or deleted, provided as a useful reference/ example for how a particular section of an air quality report can be completed (purple text). The template lists sections that should be included in the air quality report such as: project summary, project background, regulatory requirements and guidance, existing conditions, project assessment, mitigation, conclusions, references, and appendices. Not all these sections will be needed for every project-level air quality report, depending on the project and project conditions. The study concluded by applying the template to three hypothetical trans- portation projects to provide better understanding to the reader on how to use the template for a specific project and how to become more familiar with docu- mentation for new or unfamiliar emissions or dispersion models. Quantitative Particulate Matter Hot-Spot Analysis Best Practices Guidebook, Version 2.0, CTAQ-RT-17-317.02.6 This research resulted in a guidebook that is a detailed summarization of modeling quantitative PM hot-spot impacts for transportation projects. It is designed to guide a California Department of Transportation (Caltrans) air

Literature Review 11   quality staff person through the entire modeling and documentation chain for a transportation project. The guidebook includes an overview of the analysis procedure, information on estimating the level of effort required for an analysis, guidance for reviewing and verifying AERMOD modeling results, a discussion of potential mitigation measures, and guidance for developing and stream- lining PM hot-spot analysis documents. Although written for Caltrans staff, the guidebook is adaptable to other DOT circumstances related to PM hot-spot modeling. The most significant difference for adoption by other DOTs relates to emission modeling. California uses EMFAC while other state DOTs would have to use MOVES. Of particular value to other DOTs will be the guidebook’s discussions of how project variables affect near-road PM concentrations; a checklist for reviewing and quality assuring AERMOD results; scheduling and budgeting considerations for completing a PM hot-spot analysis, and lessons learned from Caltrans’s experiences with PM hot-spot modeling. The guidebook lists all the analysis steps, with estimates for the duration of completion of each step. It also provides a level-of-complexity estimate and a level-of-uncertainty estimate for each step, ranging from low to medium to high. The guidebook provides considerable detail on AERMOD review and quality assurance (QA). The review guidance includes such factors as meteorological data, receptor placement, terrain features, background concentrations, and design values, among others. The guidebook also lists several mitigation measures that could be considered to reduce predicted PM concentrations and discusses how those measures are effective in reducing PM levels. The guidebook concludes with ways to organize and develop PM analysis documents and potential best-practice methods to streamline that documentation. It has three examples of PM hot-spot studies and some practical real-world lessons learned that could be useful for future PM hot-spot analyses. Assessment of Quantitative Mobile Source Air Toxics in Environmental Documents – NCHRP Project 25-25/Task 70 Final Report Given the concerns raised regarding the treatment of MSATs in environ- mental documents for transportation projects, this research project sought to increase knowledge regarding the MSAT impacts of transportation projects, and especially the scope of MSAT analysis that may be most warranted for those projects. The research was accomplished by: (1) examining 30 trans- portation project environmental documents to determine differences among project alternatives, time frames, and geographic scales; and (2) modeling of two types of representative transportation projects (highway widening and an intermodal freight terminal) to compare differences in MSAT impacts among project alternatives over time, against background levels and identified health risk comparison levels for each pollutant. MOVES2010a was used to generate emission estimates and CAL3QHC/R was used for the highway widening project analysis, while AERMOD was used for the intermodal freight terminal project. Major findings from both phases of the research include the following: • Major transportation projects typically generate small impacts on total MSAT emissions and local MSAT concentrations, compared to the no-build alternative and compared to broad trends associated with changing fleet emissions over time. The impacts (positive or negative) will depend upon the specific conditions of the project.

12 Practices for Project-Level Analyses for Air Quality • The impacts of transportation project alternatives on MSAT concentrations are generally small relative to background levels of pollutants (5% to 15% in the case examples conducted for this research). • While the impact of the project versus no-build alternative was small, the contribution of local transportation sources was on the same order of magnitude as background levels for most pollutants. • Current background pollutant concentrations for the analyzed pollutants usually exceed one- in-a million 70-year cancer risk levels but were lower than one-in-a-million 100-year cancer risk levels and other non-cancer chronic health risk levels of concern for most pollutants. Adding the contribution from the local transportation sources did not change whether any risk thresholds were exceeded in the case examples. • The relative contribution of transportation sources (versus background) varies substantially by pollutant, with the highest relative impacts observed for diesel particulate matter and naphthalene. • The relative impacts of project alternatives were projected to remain consistent over time. However, the absolute impacts (positive or negative) became smaller as emission rates decreased due to cleaner vehicles and fuels. In nearly all cases, decreases in emissions per vehicle more than outweigh any increases in traffic over time periods of 10 to 25 years. • In the highway project case example, intersections generated MSAT concentrations that were much higher than those modeled for highway mainlines. This was due primarily to the closer proximity of receptors to vehicles at intersections, and secondarily to higher emission rates due to lower traffic speeds at intersections. • The intermodal freight terminal case example found the greatest pollutant concentrations to be directly adjacent to major roadways in the study area. The physical (site) design of such projects, and the location of both on- and off-road emissions sources relative to nearby popula- tions, will affect the relative impacts. • Meteorological conditions make a difference. For example, an area characterized by generally light winds is estimated to have a traffic contribution to pollutant concentrations that is two to three times higher than an area where moderate to higher wind speeds are more prevalent. AASHTO Practitioner’s Handbook: Addressing Air Quality Issues in the NEPA Process for Highway Projects This handbook is primarily designed for DOT environmental staff members who are familiar with the NEPA process but might not be as familiar with air quality aspects and issues. Accordingly, the handbook begins with a basic primer on transportation conformity, including the distinctions between regional-level conformity requirements and project-level conformity requirements, and on how project funding and approvals depend upon positive conformity determi- nations, both on a regional- and project-level scale. Regarding NEPA, the handbook discusses NEPA and Council on Envi- ronmental Quality (CEQ) expectations, documentation, comparative anal- yses among alternatives, and consideration of air quality in categorical exclusions (CEs). The handbook recognizes that the air quality issues to be discussed in a NEPA document will typically depend on the scale and scope of the project. It identifies a series of air quality-related issues that could be included in a NEPA document. The handbook also discusses MSATs with reference to FHWA guidance. It further discusses GHG analyses, recognizing that analyses for that pollutant are often determined on a case-by-case basis. It suggests that any state- or local- level environmental requirements be included within the NEPA document.

Literature Review 13   It has a checklist of factors and issues for determining the applicability of various air quality requirements and how to address them in a NEPA document with clarity and completeness. These include such issues as • Description of pollutants considered, • Regulatory requirements, including transportation conformity, • Existing conditions (baseline), • Models, methodologies, and data sources, • Construction emissions (as needed), • Indirect and cumulative effects, and • Comparative analysis results of assessed pollutants. The handbook also addresses updating the air quality analysis for a project after the completion of the NEPA document, whether for NEPA purposes or for transportation conformity purposes. Using these sources, along with the federal guidance, would allow a DOT to develop a project- level air quality analysis that would not only meet federal requirements but also provide an analysis that is complete, thorough, and meaningful to both technical and non-technical readers and reviewers.