Yes, it is legal while there obviously is an impact on or restriction on your life, you can go about most of normal life--any chores, family events, recreation, etc. that is within a 30-mile radius, which is a considerable radius. The restriction you describe is not sufficiently restrictive so as to require you to get extra pay for being on call and an employer has a right to put terms and conditions on work, such as the conditions you describe. Your employer can require this of you, and does not have to pay you extra for it. Your recourse is to seek other employment, if you don't like the working conditions of this job.