Sewer ejector basin outdoors - how far from house?

I'm installing a Zoeller 24" x 60" outdoor sewer ejector basin next to a garage that is being converted to an apartment. The UPC (2009) does not seem to indicate any required distance from a structure. Does anyone know of any requirement about this?

I usually install it as close as possible. Other than that there is no requirement, although an exterior installation is seldom preferable to an indoor one.