Question: BEEST tells me that I have not entered the receptor elevations. I want flat terrain in my model. What do I need to do to enter zero elevation for the receptors?

Answer: To set the option for flat terrain, click the "Control Options" button on the toolbar at the top of the screen in BEEST. After that, the next step depends on which model you are running. If you are running ISCST3 or ISC-Prime, click the "ISC Options" tab. Click the check mark next to the words "Consider Elevated Terrain" to clear the checkbox. If you are running AERMOD, click the "AER Options" tab. Click the radio button next to "Non-Regulatory Default." This will enable the options in the Non-Default Options section of the screen. Click the checkbox next to "Assume Flat Terrain" to set the option for flat terrain.