CDAWG October, 2014

1. Deploying Mobile Sampling Technologies (MSTs) in Developing Emissions Inventories for Air Pollution Control Plans CDAWG October, 2014 Clark County, Nevada Department of Air Quality (DAQ)

2. Presentation Overview • Introduction to Mobile Sampling Technologies • OTM-34 for Mobile Sampling Technologies • Road Dust Emission Inventories • Road Dust Influences • Defining Objectives of Measurements • Mobile Sampling Plan Development • MST Sampling Route Design Constraints • Execution of Paved Road Dust Inventory

3. Introduction to Mobile Sampling Technologies • Mobile Sampling Technologies (MSTs) consists of fitting sampling instruments to vehicles to sample road dust emissions • Includes particulate samplers for source and background measurements • Data recording linked to Global Positioning System (GPS) • MSTs have matured into an effective sampling method • Methodological approach endorsed by USEPA as “OTM-34” • Sampling method accounts for all factors influencing road dust emissions • Road dust emissions are considered “open source” • Road dust not emitted through a stack or vent • Road dust emissions are dispersed and considered fugitive in nature

4. Other Test Method: OTM-34 • Method to Quantify Road Dust Particulate Matter Emissions (PM10 and/or PM2.5) from Vehicular Travel on Paved and Unpaved Roads • Method appropriate for any paved or unpaved road that is 328 feet or greater in length • Main purpose to provide regulatory agencies, the regulated community, and the public at large with potentially helpful tools in the development of emission measurement methodologies • May be used for Federally enforceable State and local programs provided they are subject to an EPA Regional SIP approval process • OTM-34 sets forth performance standards for MST systems

5. Other Test Method: OTM-34 (continued) • Development of OTM-34 method began with Clark County’s submittal of peer-review Phase IV MST report to USEPA Region 9 and OAQPS • The Center for the Study of Open-Source Emissions (Dr. Chatten Cowherd) continued development of the OTM for MSTs • OTM-34 completion time frame start to finish, was approximately 5-years • OTM-34 should simplify approval process for use of MSTs for SIPs and RTPs

6. Road Dust Emission Inventories • Total mass emissions are quantified by grams per vehicle mile emitted multiplied by total miles traveled • Grams per vehicle mile emitted varies by • Road functional class • Road surface conditions • Vehicle speeds • Vehicle type and traffic volume • Road improvements (medians, paved shoulders, curb and gutters)

7. Road Dust Emission Inventories (continued) • Emissions are developed and quantified for each functional class; the sum of which equals total emissions • MSTs provide more robust paved road dust inventories compared to other methods • Uses actual road dust measurements • Provides the means to sample large segments of the road network in a shorter period of time • Much safer process to characterize paved roads than the older AP-42 silt sample collection for use with the predictive equation process

8. Road Dust Influences • Road Functional Classes Typically Have Varying Emission Rates • Road Functional Classes in Urban Areas Include • Freeway/Expressway • Principal/Major/Minor Arterial • Major/Minor Collector • Local Roads • Road surface conditions Influencing Emission Rates • Surface silt loading • Well maintained versus degraded surface • Surface roughness

9. Road Dust Influences (continued) • Road dust emissions rate for local roads usually doubles that of principal arterials, as a result of higher silt loadings • Vehicle speeds • Paved road shoulders – presence reduces surface silt loading • Adjacent land use • Vehicle weight, bulk • Number of wheels/axles (tractor trailer versus automobile)

10. Examples of Mobile Sampling Technologies (MSTs) DRI “TRAKER 1” (Testing Re-entrained Aerosol Kinetic Emissions from Roads) Desert Research Institute, Las Vegas, NV.

11. Examples of Mobile Sampling Technologies (MSTs) DRI “TRAKER 2” (Testing Re-entrained Aerosol Kinetic Emissions from Roads) Desert Research Institute, Las Vegas, NV.

12. Examples of Mobile Sampling Technologies (MSTs) (continued) UCR CE-CERT “SCAMPER” (System of Continuous Aerosol Monitoring of Particulate Emissions from Roadways) University of California Riverside, College of Engineering, Center for Environmental Research and Technology

13. Examples of Mobile Sampling Technologies (MSTs) (continued) H/T meter (humidity and temperature meter) South Korean Road Dust Monitoring Vehicle (RDMV) DGPS (differential global positioning system)

14. Examples of Mobile Sampling Technologies (MSTs) (continued) Pump at the roof Cyclone Branch to the Instruments TEOM and ELPI Tube (10 cm diameter running to roof) “Sniffer” Mobile Laboratory Metropolia University of Applied Sciences, Department of Technology; and Department of Physics, University of Helsinki, Helsinki, Finland Conical Inlet behind the left rear tire of Sniffer

15. Defining Objective of Measurements • If a comprehensive road dust inventory is needed, then the sampling route: • Must encompass all functional road classes • Must encompass the varied infrastructure conditions present in the modeling domain • For a comprehensive inventory, the sampling must be scheduled to avoid major holidays or events that cause atypical traffic patterns • If the inventory is focused on a specific source type, then the sampling route will be designed around these specific sources

16. Mobile Sampling Plan Development • Obtain maps of targeted road network area by functional class • Need infrastructure information – paved shoulders, curbs, gutters and pavement condition • Perform windshield survey of roadway network to develop the sampling plan – Identify • Location of major sources of dirt track-on and current construction sites • Other factors influencing road dust emissions (pavement conditions)

17. Mobile Sampling Plan Development (continued) • Survey information used to design an efficient route that encompasses all functional road classes • Include sampling segments and varied infrastructure conditions for the domain in which SIP/RTP is developed • Develop sampling route which can be efficiently traversed by the MST • Immediately prior to sampling event, resurvey route to identify any needed modifications

18. Functional Road Classification Map1 1 Las Vegas Valley Urbanized Area

19. Typical Sampling Course Map

20. MST Sampling Route Design Constraints • Must consider MST technical limitations in designing sampling route • Acceleration, braking, cornering and turn radius characteristics • Sampling rate and averaging characteristics • To sample ten data points with one second sampling, you need • 513 feet at 35 mph & 660 feet 45 mph • Additional distance is required for acceleration and deceleration on each sampling segment

21. Execution of Paved Road Dust Inventory • Inventory can be further refined by importing formatted data into a traffic demand model to obtain a link-level emission inventory • Enhance robustness of the road dust emissions inventory by incorporating a statisticians assistance in determining a statically valid number of miles sampled for each road class

22. Example of Traffic Demand Model Link-level Emission Inventory Output

23. Questions? Contact:Russell S. Merle Jr., Senior AQ Planner Clark County Department of Air Quality Telephone: 702-455-1662 merle@clarkcountynv.gov