Officewear for industrial/blue collar environments?

Hey gang. I am looking at starting a new work project where I'll be doing technical office work within an industrial plant, while also doing field trips out and about in the plant itself. The office vibe is pretty relaxed business casual but I'm not sure if I can get away with jeans and a t-shirt. I am very curious to hear what others are wearing in environments that are not the usual urban corporate office. Thank you :^)