I had one other chick pass from the coccidiosis a day after bringing them inside and starting the Corid. It was the chick that looked unwell and alerted me to the issue. I'm down to 26 out of 30

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Today is day 4 of the Corid treatment and thankfully I'm not seeing anymore bloody, runny stools and they are going bonkers being in a small brooder after having more space outdoors.
I completely moved the open air coop/run to a different location since I couldn't think of any other way to 'clean/sanitize' the dirt/sand.
I planned to move the run eventually anyway. The reason I put the run in that location initially was to let the chickens till the soil and remove weeds before planting a garden for them.
Is there anything I should/could do to before planting a garden there? Or should I just change the location all together? I'm not opposed to removing a few inches of the soiled dirt and adding in gardening soil if it would make a difference.
Now that I know coccidiosis is present in my yard any future chicks will be getting medicated feed until they're at least 16 weeks old.