While removing old moldy caulk in my shower, I discovered water damage. After removing the soggy, molded green board, I could see into the space where my jacuzzi tub sits. Much to my surprise, there was dirt in that space, alot of dirt. Why would there be so much dirt sitting on my foundation? The house is about 19 years old. Do they put dirt on the foundation so the fiberglass tub isn't sitting directly on it? Or is it a sign of something else?