If you want something that water won’t penetrate use Bentonite, it’s a clay product that packs in like cement. I used it on my well I had drilled, the guys poured heaps of it about 6’ deep up the grade level to prevent ground water from seeping into the well.No. Water drains well through crusher rock - it is actually what you use to create drainage passages - a simple French drain is just a ditch filled with crusher rock because the water will flow easily through the crusher and away from where you don't want it.
A berm is to exclude water so is usually heaped up dirt. My thick clay soil makes wonderful berms because it takes ages for water to penetrate it so it just flows elsewhere.
I just made a long post and the issue of water heading to the French drain is what is worrying me.
Pictures and a diagram will help.
Gosh I love that stuff!