Recently had septic pump problems.
The fellow doing the repairs noticed that soil and water were probably
making their way into the pump chamber on one side. He suggested I dig
a channel to allow the water/drainage to make its way around the pump
chamber.

I've dug most of the channel. Now I'm wondering what to fill it with.
At first I thought I'd just place the original grass back on top. But
that would be difficult to maintain and dangerous for walking.

So I'm thinking about filling it with small stones. Is this the best
way to go?
Any suggestions would be appreciated.

TIA