As a subconsultant to Tetra Tech, Fishbeck worked with the Macomb County Public Works Office (MCPWO) to scan the 8½ Mile Relief Drain, a 4.5-mile, 11.5- to 12-foot diameter pipe. The pipe was scanned to identify its location and elevation, determine its invert elevation, and establish the size of taps and leads entering the pipe.
Over four days, Fishbeck transferred GPS control into the pipe from various manhole locations. When inside the pipe, total station instruments were used to gain control from the GPS and provide the exact location of each scan station as well as locate the pipe floor where flow was present. A prism was mounted on top of the scanner, so coordinates could be applied and used later in the registration of the point cloud data. In total, 230 scan positions were obtained to fully map the entire length of the pipe. Five Fishbeck personnel and two MCPWO employees worked to complete the field portion of the project. Appropriate PPE was used during pipe entry, and rescue personnel were present at upstream and downstream manholes when staff were inside the pipe. The gathered data will be used to place in-system storage devices to store flow in the pipe during large rain events.
Scanning the relief drain provided an accurate 3D point cloud model, which was used to document the condition of the pipe, including every joint and defect. This information provides MCPWO vital data to assess the overall condition of the system.
