Getting Smart with Meteorological Towers

Working at ALL4 and having the opportunity to deploy and maintain meteorological towers is a meteorologist’s dream.  During my first week at ALL4, I was deployed into the field of western Virginia to perform a meteorological audit of instruments on a 30 meter (~100 foot) meteorological tower.  Yes, that’s right, I wasn’t even 5 hours into my first day of work, and I was in a car driving 8 hours to a remote greenfield site, to make sure that the instruments on the tower were operating correctly and within U.S. EPA’s standards.  Not only was this a fantastic opportunity for a recently graduated atmospheric sciences major, but it gave me the chance to test out my new winter coat in the polar vortex that the eastern U.S. experienced last winter.

All kidding aside, working with meteorological towers has been a very interesting experience.  Just as there are no two (2) snowflakes alike, there are no two (2) meteorological towers alike.  In my one (1) year of experience at ALL4, I have performed three (3) instrument audits on existing towers, set up one (1) temporary tower for a pilot study, organized calibrations for our audit instruments, and researched and purchased countless new equipment.  I have contacts at multiple companies that know me by name at this point!  I have quality assured meteorological data remotely for the towers that we maintain as well as post-processed data for use.  Our newer systems even include mobile apps for real-time monitoring of the tower data!

So why would a facility need a meteorological tower?  Surely, not all environmental managers are as intrigued by the weather as I am and would just appreciate knowing the wind speed and direction at their facility.  The most common reason that our clients would need to install and maintain a meteorological tower is to collect representative meteorological data for air dispersion modeling.  When an existing or new facility plans a project that will involve major source Prevention of Significant Deterioration (PSD) permitting, and the estimated potential to emit emissions are greater than the significant emission rate (SER) thresholds, the facility is required to perform air dispersion modeling for those pollutants exceeding the thresholds.  Air dispersion modeling requires meteorological data used in the dispersion equations to determine the movement and extent of emission plumes.  Based on U.S. EPA 40 CFR Part 51, Appendix W guidelines, the meteorological data used for modeling requires the use of five (5) years of representative National Weather Service (NWS) meteorological data or one (1) year of site specific data.  Site specific data is preferred for air dispersion modeling, since it provides the exact conditions at a site.  There are many considerations for site specific data that include the representativeness of the monitors, the data completeness, the system accuracy and resolution, as well as quality assurance and quality control (which includes the polar vortex audit that I had the pleasure of completing my first week at ALL4).  There is a fair amount of planning and care involved in setting up and maintaining an onsite meteorological tower, especially to stay in compliance with U.S. EPA guidelines and requirements.

Onsite meteorological towers are also necessary to support a variety of facility operations.  Meteorological data, including wind speed and direction, temperature, pressure, and precipitation are used by facilities as support for fugitive dust issues or odor complaints.  Wastewater treatment plants utilize rainfall, barometric pressure, and solar radiation data.  Temperature and barometric pressure data can be used during stack testing activities for flow calculations.

In addition, the proposed amendments to the 40 CFR Parts 63, Subpart CC and Subpart UUU will require all petroleum refineries to collect onsite meteorological data.  These data include wind speed, wind direction, temperature, and barometric pressure.  The meteorological data will be crucial in determining background concentrations and validating fugitive benzene emissions above and below the corrective action level.  I had the pleasure of setting up a pilot benzene fenceline study at a Pennsylvania refinery last year, where ALL4 deployed a temporary meteorological tower (about 6 meters tall).  This tower was equipped with all of the required meteorological instruments, which were quality assured to be within U.S. EPA’s standards.  ALL4 ran the temporary tower for about two (2) months, while also collecting several passive benzene fenceline samples.  The meteorological data collected in parallel to the timing of the samples proved to be a critical component to understanding and diagnosing the benzene concentration results.  If your refinery is interested in setting up a pilot study to see where your fugitive benzene emissions stand, or would like to get more information about the proposed benzene fenceline monitoring rule and required meteorological tower, contact Nick Leone (nleone@all4inc.com, 610.933.5246 x121).

As the weather heats up, I’m itching to get back in the field and work with meteorological instruments.  Whether it’s a temporary two (2) month tower or permanent 30 meter tower, you can bet that I will be involved!  Plus, anything warmer than the -8⁰F polar vortex that I experienced last year is good with me!

What instruments are on your meteorological tower at your facility?  Are they currently operating?  Are they being properly quality assured following U.S. EPA criteria?  These are important questions to ask before you have an event where you need to rely upon that data.  Leave a comment below, or reach out to myself (adepasquale@all4inc.com) or Dan Dix (ddix@all4inc.com) if you have any meteorological tower-related comments or concerns!