A specialty horizontal conduit was needed to cross 9 utilities along the directional bore path at a target depth of 4 feet below ground surface. Preventing injuries to workers and damage to the underground utilities was imperative to all parties involved with the project. This case study details the design and methods used to safely drill past the nine utilities for a successful installation.
Background
A former gasoline station site was impacted with petroleum in the soil and groundwater. Further complications were the multiple underground utilities near the building. A specialty horizontal conduit know as Horizontal Remediation Well was installed via directional drilling along the roadway beneath the sidewalk to clean up the soil and groundwater.
Approach
The horizontal remediation wells needed to approach the utilities at a target depth of 4 feet bgs. Underground utilities in the area included sanitary sewer, water, gas, power, and communication lines, which traversed perpendicular to the proposed horizontal well path at depths of 3 feet to 6 feet bgs. But the question as to how to safely cross these utilities had to be addressed early in the design process. The consultant and their client specified safe utility clearance through use of an air-knife/dry-vac to uncover the utilities for visual verification of depth, diameter, and trend of the utility. Odyssey Environmental, LLC worked ahead of Directional Technologies’ directional drilling crew to uncover the utilities prior to directional drilling of the pilot bore. Like many scenarios, the marked utilities were slightly off the surface marking, and deeper than street plans depicted. One challenge was how to advance the drill bit safely past a 10-inch sewer early in the bore. To safely cross the utilities, Directional Technologies continuously and carefully tracked the location and depth of the drill bit using the walkover locating system. When possible, the crew visually verified the bit was passing safely over or under the utilities, sometimes within 5-inches of the utility.
Results
With careful planning and execution, the horizontal remediation wells were placed at the target depth. This impressive horizontal well installation was successfully and safely completed through careful planning and execution by the consultants and subcontractors.
Directional drilling across 9 utilities is not a project for the low bidder. Our clients’ understanding of the complexity of this project, along with experienced Master Directional Drillers and our on-staff engineers, made this project possible.
Solve your complex underground utility projects by calling our experts at 203-294-9200.
