Soft berms are now rock solid even here in Western Maine. With the lack of significant snowfall I have witnessed FMJ casings as far as 50' from safety berms back toward the firing line. Another word of caution is if the angle of your berms are less than 50 degrees the ricochet may create harm to innocent victims as far as 1500 feet from your target.

Your established firing line should be no closer than 65' to your safety berm.
Just a word of caution your members should be cognoscente of. Reinforce all individuals at the range must wear eye and ear protection at all times.