That's an understatement .
another material that's great is cardboard for sliding objects .
They also have gfci breakers check with your local codes.. any power going outside should be protected...
Food for thought you might want to stay further away from your walk until you have the rest of the pond DONE fold the liner in . take out the rest of the soil, to where you want to be as finished, lay the rubber back down. this way you won't loose the walk ... i was thinking asphalt, your lucky its pavers but your still better off not disturbing it. Though having a rock cut into the walk preferably flush and where it comes out from the walk its a destination spot to feed or have the rock stick up this will tie the walk in with the pond. at 1:38 is a example of what im talking about . there are other views as well