It 's expected to arrive Thursday or Friday , an engineer overseeing the drilling said . Platform , called Plan C , will be part of efforts to drill to reach the surface . Plan The drill being used in Plan A -- a type usually used in mining operations -- reached a depth of 171 meters ( 187 yards ) A drill is making progress ; Plan B drill has hit a rock . 33 miners have been trapped for 35 days , 100 feet under the surface .
It 's expected to arrive Thursday or Friday , an engineer overseeing the drilling said . Platform , called Plan C , will be part of efforts to drill to reach the surface . Plan A drill is making progress ; Plan B drill has hit a rock . 33 miners have been trapped for 35 days , 100 feet under the surface .