Life would be a lot simpler if I lived on an area with a flat lawn but you can't get everything it seems. And so I spent a lot of time filling in the forms so that any concrete I pour into them doesn't end up at the bottom of the hill and pounding a lot of stakes and bracing to keep the forms in place when the immense weight of the concrete is poured into the form.
Initially when I started this project, I had hoped that the dirt from the rat barrier would be enough to fill up much of the inside so that things were level but after digging one side of it, I canned that idea. A rat barrier is a narrow trench that get dugs in around the inside perimeter of the future concrete slab to prevent rodents and such from digging up underneath the concrete and making it a deluxe apartment. I also think it probably helps keep the structure rooted in place. The dirt from digging the rat barrier is dried out clay and it would take a lot of moisture and effort to pack it down dense enough that it wouldn't settle over time and cause cracking problems in the slab. So I am just going to toss it around the outside and use it as backfill when I remove the forms and seed it down later. Instead, I am just going to get a load of sand which packs down easily to take up much of the low spots.
Getting sand is easier said than done. It seems like it always takes me several messages left over a period of a week before I ever get a call back. After a week and several messages, I finally got a call back and sand is supposed to be delivered in a couple days, hopefully before a big rain. That way perhaps the truck can back down the hill into my backyard and dump the sand right into the form. If not, I will be doing a lot of grunt work moving it wheelbarrow at a time down a fairly steep slope.