Grade Boring is an HDD methodology used to install a pipeline to a predetermined grade.  These installations are typically gravity flow sewer and storm water collection system pipelines.  Conventional HDD equipment is combined with specialized locating and steering equipment to complete these types of bores.  Of particular importance is the drilling technique employed by the drill rig operator.  A considerable amount of drilling experience is necessary for these bores to be performed successfully.  

    Many of the grade bores being performed today are for the installation of sewer main lines.  In many developed areas, sewer mains tend to be deeper than other existing utilities and often are located below roadways and other public infrastructure.  These site conditions pose many challenges for the traditional open trench method of construction.   When considering weather HDD is a viable alternative, some factors to assess would be the following:

    When considering a grade bore for your project, it is important to carefully consider the project requirements and compare them to the capabilities of this method to maximize the chances for a successful project.  Today, installing bores on grade with HDD equipment is less than an exact science.  As technology continues to improve, so too will the accuracy and capabilities of this methodology.  In the mean time, it is important to effectively assess the risks associated with grade boring and leverage them against the alternative construction methods available for the project.

    Generally grade bores fall into three different categories of difficulty.  The first is the moderately difficult grade bore.  These bores usually consist of slopes that are 2% or greater.  Some of these bores can even be completed utilizing conventional locating and steering equipment and have a high rate of success.  Next is the difficult grade bores where slopes range from 1% to 2%.  These bores require special locating and steering equipment as well as an experienced drill crew in order to maximize the rate of success.  Finally there is the critical grade bore.  These bores generally range from 0.5% to 1.0% slope and are the most difficult bores to complete.  Much consideration needs to be given to an HDD project where the grade is critical.  

    Apollo Trenchless, Inc. has been on the leading edge of successfully installing on-grade HDD crossings.  Through the combined use of HDD grade-boring locating equipment, experienced operators employing advanced drilling techniques and the application of computer modeling of survey information, we boast some of the best averages in the industry for successful installations on grade.  Please contact us for more information on the feasibility of grade-boring for your project.  

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