Aging infrastructure is one of the most serious problems facing Michigan. Pipe rehabilitation/improvement techniques can save communities millions of dollars. Historically, underground utility piping had to be installed by open cut excavation, or jack-and-bore operations. These techniques are disruptive to the environment, vehicular and pedestrian traffic. Construction zones or detour routes affect commerce and are costly from a fiscal, social and environmental perspective. While there is no zero-impact pipe installation method, more and more techniques are being developed to minimize disruption at affordable costs.

An increasing number of projects lend themselves to “trenchless technologies” including:

• Horizontal Directional Drilling
• Pipe Bursting
• Microtunneling
• In-situ lining

Horizontal directional drilling uses a computer guided boring head to open a “lubricated” underground conduit into which a pipe can be pulled. Pipe bursting uses the old pipe itself as a conduit, opening it up with a bursting head and expander to admit the new pipe, often at a larger diameter than the old pipe. Microtunneling involves pushing a pipe into a conduit opened by a remotely controlled boring machine employing a cutting head at the face. In-situ lining is a pipe rehabilitation tech-nique accomplished by inserting a flexible liner within the existing conduit and curing it, thereby sealing areas of deterioration, restoring structural integrity, and preventing leakage or infiltration. Each of these technologies, can...

• make the work almost invisible to those above-ground
• minimize traffic disruptions and detour routes
• reduce the installation and rehabilitation time line
• protect environmental features (large trees) and landscaping
• be more cost effective than traditional open cut excavation

We offer these ideas for where these technologies can best be applied...

• Horizontal directional drilling is best suited for pipes that do not have strict line and grade requirements and minimal service leads. It is not well-suited for drilling through hardpan or cobble or multiple set-ups due to the need to change direction.
• Pipe bursting may be used in areas with poor access and where the existing pipe is at the desired line and grade. It is not as well suited for applications where the existing pipe has experienced significant line or grade distortions or where there are many leads needing to be connected.
• Microtunneling is generally used for larger diameter pipes (greater than 36”) where excavation is impractical, and the soil conditions are permissive.
• In-situ lining is often a cost effective way to rehabilitate a pipe, if the conditions are well documented and the pipe is not too deteriorated or distorted. High groundwater is a challenge as it impedes effective curing. A combination of pre-grouting, point repairs and lining can be the most cost effective way to rehabilitate a pipe.

HRC has successfully used these techniques on many projects, comprising tens of thousands of feet of piping in a variety of environments. We don’t view these techniques as cure-alls. Rather, they offer an opportunity to explore better ways of delivering high visibility/impact projects in cost conscious times. HRC collaborates with the Center for Underground Infrastructure Research and Education (CUIRE) to model and quantitatively evaluate the impacts and costs of these trenchless technologies in comparison with conventional construction techniques. We utilize our own project experience to assess many factors before recommending one of these techniques to our clients. Having knowledgeable engineers and construction observation staff that have experienced successful trenchless technology projects is a great resource when we evaluate the ideal design for a particular pipe utility project.

Horizontal Directional Drilling (HDD) Pipe Bursting Rigid Pipe Slip Lining Grouting Tunneling		Micro Tunneling Jacking and Boring Closed Circuit Interior Pipe Televising Cleaning Root Removal