Paver Block Problem
I'm not sure if I understand you question, but if you want a your 8 ft circle level, you could build a retaining wall at the "front" of the circle, backfill it with soil from the "rear" of the circle or you could remove the soil from the rear and build a retaining wall to keep the 18" from falling.
There are concrete wall blocks that are sold at a few homecenters that could work for you.
If you want the circle to follow the slope, you could mark the circle out on the slope,find some flexible edging material and fit the edging material into the soil, following the mark on the hillside. Dig out the material inside the circle to the depth for your gravel and sand from the surface of the hillside and then work upwards from the "front" of the circle to the "back". The edging could maintain the curve and by working from the front to the back, the pavers at the "back" of your circle would be supported by those in the front.
- 15 Old House Features We Were Wrong to Abandon
- 17 Tiny Bathrooms We Love
- 20 Insanely Easy 60-Minute Home Improvements
- 70 Gardening Tricks and Ideas for Total Beginners
- 16 Inventive Beds You Can Make Yourself
- Top 10 Classic DIY Projects for the Outdoors
- 15 Once-Popular Household Items That Are Vanishing
- 159 Smart Storage Ideas for the Whole House
- 30 Things Every Adult Should Know How to Do
- 10 Wise Ways to Get Rid of Pests and Critters
- Before and After: 9 Totally Amazing Mobile Home Makeovers
- Top Tips for Keeping Countertops Like New
- 15 Amazing Things You Can Make with $0 Scrap Wood
- 14 Ways to Get More Kitchen Counter Space
- Assembly Required: 15 DIY Kit Homes
- 18 Bathroom Updates You Can Do in 1 Day
- 9 Tried-and-True Methods of Eliminating Weeds
- 15 Fast Fixes for Your Home Facade
- 11 Clever Alternatives to Kitchen Cabinets
- 7 Easy Budget-Friendly Backyard Makeovers