Sand in books

It's that time of year where hard cover books may be coming back with sand in them. If the book has been loaned out to another library's patron, e.g. Eastham, we have no control - as the patron has not seen our signs and we would not receive any fees charged. However, if it is one of our patrons and a hard cover book is returned with sand, they will be charged a $5 fee since we have to replace the plastic cover. There are signs around the library telling people of the potential fee.