Evaluation of the EPA Drift Reduction Technology (DRT) Low-Speed Wind Tunnel Protocol

The EPA's proposed Drift Reduction Technology (DRT) 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 m∕s and 2.5 m∕s, following the prescribed protocol. Overall, the data followed anticipated trends with a few unanticipated results observed, which could be addressed in future iterations of the protocol. There were some difficulties meeting the proposed protocol data quality requirements. 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. The protocol was tailored such that the collected data would directly input into a dispersion model (most likely WTDISP). However, 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the time requirements, which require approximately nine times that of the high speed protocol (90 min versus 10 min, unpublished data), there is a definite need to modify the existing protocol to insure equitable implementation of the overall DRT program.