have a length in the range of about 1 meter to about 15 meters the oil to be recovered enters the recovery port 403 as shown by arrow 404 the recovery port 403 is secured and sealed to the tunnel liner 401 by for example a flange assembly 405 the first section of a recovery plumbing assembly which may also be called a well head assembly houses a main shut off valve 406 which can shut the recovery port off completely for example if it is communicating only with water or air and not the desired oil to be recovered the next section houses a window or viewing port 407 which may optionally be used to determine visually the nature of the fluid entering the recovery port 403 for example if the fluid is predominantly oil it will be light brown to black fluid if the fluid is predominantly water it will be light brown to clear fluid if the fluid is predominantly air it will be a light to clear fluid either with many entrained bubbles or little or no liquid content the next section houses a sampling tap controlled by a valve 408 and can be optionally used to collect a sample of the recovered fluid 409 for further testing and analysis of the fluid entering the recovery port 403 the next.