Project Number: 3625-11630-002-09
Project Type: Reimbursable

Start Date: Sep 01, 2007
End Date: Jan 01, 2009

Objective:
The objectives of this study are to 1) measure particulate and odor constituents across an existing vegetative buffer at a swine production facility, 2) conduct scale model wind tunnel experiments of vegetative buffer effects on air flow for the field site using a model of the existing buffer and several potential buffer designs, and 3) complete an economic assessment of vegetative buffer establishment and maintenance costs at the farm and county level for Iowa.

Approach:
A combination of field monitoring and scale model wind tunnel experiments will be completed along with an economic analysis to determine the efficiency and feasibility of vegetative buffers to mitigate swine odor and particulate transport. Particulate concentrations in eight particle size ranges from 0.3 to 10 microns will be monitored continuously for 5 months at a swine production facility with an existing vegetative buffer in central Iowa. Particulate profilers will be located adjacent to the swine housing unit, within the buffer, and outside the buffer. Ambient weather conditions at the site and wind speed, air temperature, and humidity will be measured next to each profiler. Plant tissue samples will be collected monthly and analyzed using thermal desorption techniques to identify and quantify odor constituent deposition/adsorption. An intensive 2-week gaseous odor measurement period will take place during the field monitoring to identify and quantify odor constituents in the air at each particulate profiler location. Field data will be analyzed to determine the net reduction in particulates and odor across the vegetative buffer. Variation in trapping efficiency with time will be correlated with local microclimate data. The wind tunnel component of the study will involve detailed hot film anemometer surveys of air velocity and turbulence downstream of tree models and tree models with model swine housing units at 3 air velocities and varying approach angles (perpendicular to parallel in 15° steps). Measurements will be made with a scale model replica of the field monitoring site and then with the same building model and different size/spacing/arrangements of tree models to evaluate different buffer designs. Flow visualization will be used with the velocity contour maps to determine zones of minimum air velocity likely to optimize particulate and odor capture by each vegetative buffer. Wind tunnel data will be analyzed to compare velocity reduction among the various model buffer designs to identify the design(s) that have the best combination of velocity reduction under varying wind direction. A farm level and county level economic analysis will provide a comprehensive overview of the potential financial requirements to individual hog producers who are interested in retrofitted vegetative buffer systems and for those who are interested in building the cost of vegetative buffers into plans for new construction. This analysis will utilize air photos and GIS data layers for Iowa to estimate the potential costs associated with adoption of this odor mitigation strategy and what level of public investment may be needed.