Microtunneling is an effective method of installing pipelines beneath highways, railroads, runways, harbors, rivers, and environmentally sensitive areas where a maze of underground utility lines already exist. Microtunneling is a digging process that uses a remotely controlled microtunnel boring machine (MTBM) combined with the pipe jack-and-bore method to directly install pipes underground in a single pass. This process avoids the need to have a long stretch of open trench for pipe-laying. Microtunneling includes these steps:

• Excavate launching and reception shafts at opposite ends of the tunneling drive.
• Hydraulic jacks in the launch shaft push a microtunnel boring machine (MTBM) into the earth.
• Pipes containing slurry water transport excavated spoils to the surface
• Retract the jacks and disconnect slurry lines and control cables.
• Lower a pipe or casing into the shaft and insert it between the jacking frame and the MTBM.
• Reconnect slurry lines and control cables and advance the MTBM another drive.
• Repeat the process until the MTBM reaches the reception shaft.
• Retrieve the MTBM and trailing equipment.

In addition to a hydraulic jacking system to advance the MTBM and pipe, most microtunneling operations require a lot of equipment on the construction site, including:

• A closed loop slurry system to transport excavated spoils
• A slurry cleaning system to remove spoils from the slurry water
• A lubrication system to lubricate the exterior of the pipe during installation
• A guidance system to provide line and grade control
• An electrical supply and distribution system to power equipment
• A crane to hoist pipe sections into the jacking shaft
• Trucks and loaders to transport spoils off site

What to Expect During Microtunneling

• The equipment is loud and causes vibration that you may feel in your home or business. This is standard for this method of construction.
• Both preparation and post micro-tunneling work can take a few weeks to complete. 
• Shafts are usually too large to cover safely with steel plates during non-construction hours. Site fencing is necessary to secure these areas during non-construction hours.
• There may be road closures and lane restrictions.
• There may be inactivity bewteen some phases of this process.
• Typical work hours are 7:00 a.m. to 6:00 p.m. Monday through Friday, but the contractor may schedule work during the same hours on Saturdays.