The McCool circles and the huge gravel parking lot are next to these circles- and better targets for a FF coming down. I’m also expecting (and will suggest) the pads be basically flush with the ground like mine is to prevent tripping and allow the mower to roll right over without a blade strike. I’d say lonnnggg odds of spot landing on one of those specs in the pasture.
Dave
To make sure they are flush with the ground, start with an X of level string just above ground level and about 25 foot long. Drive a 18" or 20" length of 3/4" pipe into the ground at the intersection as your center, as vertical as you can. Stop when the pipe is 4" tp 6" above grade, whatever you are comfortable with. Lay out the diameter you want, plus 12" to have room to work on the outside. Dig out what you need for the gravel base, and plan on 4" wide material for the form. Start driving in the stakes to hold the form around the circle, and using a nice straight 2X4 and a couple more strings, drive the stakes in until the top pf the stake is 3/4" to 1" lower than the center pipe all the way around. This will give the circle a crown to the concrete so it will drain water off. Add all the stakes you will require for as much concrete you will pour, then level off the gravel base nice and level. Put in whatever wire or re-rod that you want for the pad and secure it. Then comes the pouring of the concrete, and you use the center pipe and the top edge of the form along with that nice straight 2X4 you have to strike off the concrete at the basic level as you pour concrete. Work your way around and get it as flat as you can and at the proper time edge it with an edger and trowel it if it needs it, then broom some swirl in it to make it less slippery in wet weather. When cured,(let it sit at least a week or two) pull the forms, and all the stakes, then back fill with dirt right up to the edge of the concrete, and carefully tamp it as firm as you can get it. It will still settle some over a short time as it gets rained on and you can add more dirt later. When you back fill, take the outer edge out 3, 4 or 5 feet to get that taper as gentle as you can to blend everything in, more if you think it needs it. By the time grass gets established and grown it it will look like it's always been there and nothing to trip over and even a reel type mower can go right over it. You don't want to have the surface of the pad level with the ground to start with because it will settle down over time, and you have the extra advantage of some positive drainage from it by starting a little high. Winch lines can pass over it without catching , and some simple hay bales laying on the pads or any other kind of soft, weather proof material can cushion any DTing F/F model. It's a simple job, not that hard to do but if somethings are not done correctly it can be a waste of effort.
Type at you later,
Dan McEntee