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Title: Evaluation of the EPA Drift Reduction Technology (DRT) low-speed wind tunnel protocol

item Fritz, Bradley - Brad
item Hoffmann, Wesley - Clint
item Lan, Yubin

Submitted to: Journal of ASTM International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2009
Publication Date: 3/1/2009
Citation: Fritz, B.K., Hoffmann, W.C., Lan, Y. 2009. Evaluation of the EPA Drift Reduction Technology (DRT) low-speed wind tunnel protocol. Journal of ASTM International. 6:doi:10.1520/SAI102129.

Interpretive Summary: Drift associated with spray application of crop production and protection products is a continual concern for the potential detrimental effects to the environment and other neighboring cropland. As such, an increasing number of drift-reducing technologies are being developed and marketed for use with agricultural chemicals. With this growing market, there is a need to scientifically quantify and rate the effectiveness of these products in order to inform end users. In cooperation with the Environmental Protection Agency, developed protocols were tested for their applicability and feasibility in this process. A number of issues were identified, which if modified will result in an improved and more equitable science-based evaluation program for drift reducing technologies.

Technical Abstract: The EPA’s proposed Drift Reduction Technology low-speed wind tunnel evaluation protocol was tested across a series of modified ASAE reference nozzles. Both droplet size and deposition and flux volume measurements were made downwind from the nozzles operating in the tunnel at airspeeds of 1 and 2.5 m/s, following the prescribed protocol. Overall, the data followed anticipated trends with a few unanticipated results observed, but which could be addressed in future iterations of the protocol. There were some difficulties meeting the proposed protocol data quality requirements, but refined quality requirements would address this with no detrimental effect to the overall data set. Major concerns, at this point, are the feasibility of the overall protocol as well as the applicability of the final collected data. As the protocol was tailored such that the collected data would be directly input into a dispersion model (most likely WTDISP) not having access to such a model puts into question the validity and practicality of the protocol in its present form. Given the time requirements, which require approximately 9 times that of the high speed protocol (90 minutes versus 10 minutes, unpublished data), there is a definite need to modify the existing protocol to insure equitable implementation of the overall DRT program.