Our day to day range profile here in Saskatoon is for lane shooting from fixed positions. To have a match for IPSC or 3-Gun we have to apply for a temporary permit with the CFO valid only on the day(s) of the event. To get the permit we now have to submit our stage plans drawn to scale showing angles of fire and distances from targets.
That being said typical rule of thumb is to keep angles of fire at 75-90 degrees into the berms, and there's also a formula for protecting against standard aiming error, 10.7 degrees for pistol, 2.25 degrees for long guns. You use this calculation to determine a chance of a round hitting the ground and deflecting at a high angle or for a round going over the berms.
I would love to know what tools, science or expertise the CFO in SK is relying on to approve those plans. Nothing in his training as an RCMP officer or CFO would have given him the expertise to do this. By approving it, he assumes liability for any incidents.
In the Military, there are two manuals that go hand in hand. Range Construction and Maintenance, and Range Training Safety. The design guide tells you what a safe range looks like and the Range Use guide tells you have to use them safely.
While the RCMP does have their own Range Design Guidelines, they do not, and to my knowledge, never have had any documentation or policy on safe use of existing facilities.
Per the design guide, any range where the side walls meet the height requirements of a backstop, you are good to go to use that sidewall as a back stop. But in theory if you are using the left side wall as a berm, then you don't have a left side wall anymore, and in theory you would need a range boxed in on four sides in order to be legal. In any event, once legal, the question because what is safe use.
I have yet to meet a single CFO, either RCMP or provincial, that had the knowledge to properly template a range based on the inaccurate ballistic templates in the range design guide, unless they were former military.