In no case shall the workings of any coal mine be driven nearer than 15 feet to the boundary line of the coal rights of the owner of said mine, except for the purpose of establishing an underground communication between contiguous mines as provided for elsewhere in this chapter. By mutual consent of adjacent property owners, this distance may be reduced or eliminated entirely, and any operator working up to an abandoned coal mine may be permitted to work to his property line, if approved by the department, but in such cases proper precautions must be taken as provided in this chapter.