Not sure of the exact hours it’s supposedly available for public use, but I assume it basically before and after school hours (by that I also mean after-school athletics) and weekends (except for school sporting events.) Most times I’ve gone (on weekends) one of the gates was open.
But I’ve had different experiences with the gates. There’s one revolving gate on the north side of the field in the parking lot that is often open and there’s a large gate in the fence on the south side of the field (on Upshur across from Annie’s) that is sometimes open. I’ve been there when neither one is open and folks just climbed the fence.