TAG Progress Report: Landfill Odors Modeling Research

TAG Progress Report: Landfill Odors Modeling Research

C. D. Cooper, CECE Dept.,

Univ. of Central Fla.December 16, 2008

Civil, Environmental, and Construction Engineering Department

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 Dept.

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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


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Seminole County Landfill


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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


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


7

Methane Measurement Locations


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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


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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


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Example of Source Locations


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Example of Modeled Emissions Strengths

491200 491300 491400 491500 491600 491700 491800 491900 492000 492100

3184900

3185000

3185100

3185200

3185300

3185400

3185500

3185600


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Modeling Results with ISC

Trendline:y = 1.0447xR2 = 0.651

0

100

200

300

400

500

0 100 200 300 400 500

Measured Ambient VOC Concentration (PPM as methane)

Pred

icte

d M

etha

ne C

once

ntra

tion

(PPM

as m

etha

ne)


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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


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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).


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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….


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… AERMOD


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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


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Example of Screening Tool Results

490500 491000 491500 492000 492500 493000

3184000

3184500

3185000

3185500

3186000

3186500

0 ppm20 ppm40 ppm60 ppm80 ppm100 ppm120 ppm140 ppm160 ppm180 ppm200 ppm220 ppm240 ppm260 ppm280 ppm300 ppm320 ppm340 ppm360 ppm380 ppm400 ppm

Methane


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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


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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


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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

TAG Progress Report: Landfill Odors Modeling Research

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