TAG Progress Report: Landfill Odors Modeling Research

1. TAG Progress Report: Landfill Odors Modeling Research C. D. Cooper, CECE Dept., Univ. of Central Fla. December 16, 2008

2. Background • People are moving closer to Landfills • Odors can cause significant complaints, even though the landfill was there first • Odors are hard to predict – Counties need a buffer zone to limit development and provide a margin of safety • Hinkley Center project • UCF was contracted to model the dispersion of odors from landfills, and develop a method to predict a buffer zone • A two-year project that started in 2007 Civil, Environmental, and Construction Engineering Department

3. Tasks • Find a cooperating landfill • Create a way to estimate emissions of odors from a landfill • Model dispersion using CALPUFF and AERMOD to estimate buffer distances • Choose the “best” model • Create graphical tool for estimating buffer zones Civil, Environmental, and Construction Engineering Dept.

4. Seminole County Landfill Civil, Environmental, and Construction Engineering Dept.

5. Methane as a Surrogate • Methane is a major emission from landfills • For many landfills, quarterly methane monitoring data are routinely available • In a “flash of genius,” we decided to use methane as a surrogate for odors Civil, Environmental, and Construction Engineering Dept.

6. Ambient Methane Data • We now have 3 different quarters of methane monitoring data • December 22, 2006 • June 29, 2007 • June 26, 2008 • Typical monitoring report gives hundreds of measurements of CH4 concentrations near the landfill surface Civil, Environmental, and Construction Engineering Dept.

7. Methane Measurement Locations Civil, Environmental, and Construction Engineering Dept.

8. Matrix Inversion Technique • Normally, we use the Gaussian model to predict concentrations, given source strengths • By inverting the equations, we can calculate source strengths, given the concentrations • For hundreds of concentrations and hundred of sources, we needed matrix inversion • Accomplished by Dr. Kevin Mackie, a UCF faculty member Civil, Environmental, and Construction Engineering Dept.

9. New Method for Placing Sources • Voronai diagram theory • Applied to this research by Dr. Mackie • Automatically locates sources for optimal positioning relative to receptors • Results show good agreement for the three independent data sets for the same landfill • Dec. 2006 – 631 g/sec • June 2007 – 707 g/sec • June 2008 – 1233 g/sec Civil, Environmental, and Construction Engineering Dept.

10. Example of Source Locations Civil, Environmental, and Construction Engineering Dept.

11. Example of Modeled Emissions Strengths Civil, Environmental, and Construction Engineering Dept.

12. Modeling Results with ISC Civil, Environmental, and Construction Engineering Dept.

13. Times of Highest Concentrations • In one whole year the highest modeled concentrations at each receptor (264 total items) occurred in: • Day (7 a.m. to 7 p.m.) vs Night • Day - 0 • Night - 264 • Winter (Oct.-Mar.) vs Summer (Apr.-Sept.) • Winter - 133 • Sumer – 131 • All occurred with winds < 2 mph Civil, Environmental, and Construction Engineering Dept.

14. Comparing Models • Advantages of AERMOD • Run time is matter of minutes rather than hours • Smaller input file that makes errors easier to find • Easier to learn and use. • Advantages of CALPUFF • Puff tracking nature (“memory” and better handling of calm winds). • Better for longer distance dispersion • Concentration results • Both give similar outputs of concentrations (CALPUFF concentrations are slightly higher). Civil, Environmental, and Construction Engineering Dept.

15. CALPUFF vs AERMOD • We spent considerable time making dispersion modeling runs with each program • Results are different from each other, but without actual off-site monitoring data, we cannot tell which is “right” • Choice was made based on reports of accuracy in the literature and ease-of-use considerations • And the winner is…. Civil, Environmental, and Construction Engineering Dept.

16. … AERMOD Civil, Environmental, and Construction Engineering Dept.

17. Preliminary Screening Method • Chose to develop a graphical Screening Method • Green, Yellow, Red: analogy to traffic signal • Green – OK to build • Yellow – Caution • Red – Stop; do not build • To use the Method for a specific landfill, must have data for: • Methane emissions, spatially distributed • Odor-to-methane ratio (e.g., ppb H2S/ppb CH4) • Site meteorology Civil, Environmental, and Construction Engineering Dept.

18. Example of Screening Tool Results Civil, Environmental, and Construction Engineering Dept.

19. Tech Transfer Results • Two presentations at conferences: • FAWMA – Oct. 2007 • AWMA – June 2008 • Two papers submitted to journals: • J. Air & Waste Mgmt Assoc. • Env. Modeling & Software • One MS student (Veronica) graduated and working in the solid waste field (SCS-Tampa) • Another MS student (Nick) will graduate in May, 2009 Civil, Environmental, and Construction Engineering Dept.

20. Conclusions • We have developed an excellent method for estimating methane emissions from landfills • Can use existing methane monitoring reports (or may use a special monitoring study) • Method is being published • AERMOD was chosen as best dispersion model for this application • Accuracy (based on literature) • Ease of use • Graphical Screening Method • Easy to apply • Needs site specific data Civil, Environmental, and Construction Engineering Dept.

21. Plans for Next Semester • Nick will graduate in May • Still must run sensitivity tests (stability class and wind speed and wind angle) • Develop final buffer zone Screening Tool • Write thesis • Final Report • CDC to write draft final report by April • TAG to review in May or June • Submit to Hinkley Center by June 30 Civil, Environmental, and Construction Engineering Dept.