VPI: Cross Boring And Directional Drilling

VPI: Cross Boring And Directional Drilling

Directional drilling is used to install conduits under obstacles such as roads, buildings, and wetlands. A typical application for directional drilling is the installation of conduits including water, sewer, fiber, electric, and gas, into busy intersections without the disruption of traffic. Although this process can be simple, usually placed away from congestion or business activities, before drilling begins the drilling crew pre-plans the bore path to carefully avoid obstructions, such as other underground utilities. In most cases, especially in high focused areas, a cross bore or underground utilities can be found. A cross bore is defined as the intersection of an existing underground utility or underground structure by a second utility installed using trenchless technology. Cross bores result in an intersection of both utilities, compromising the integrity of either or both utility and the underground structure. However, in rare cases where a natural gas line has been inadvertently installed through a sewer or septic pipe, natural gas could enter the sewer system, creating a dangerous situation. This reason is why it is important to call 811to have all utilities marked before a digging or drilling project. But in our client’s situation, they needed to call a private utility locator, like GPRS, to help mark and map an entire town’s utilities for their directional drilling project.

Two directional drilling companies, specializing in gas conduits, reached out to GPRS because they needed help scanning, identifying, locating, and surface marking all underground utilities before they began drilling. Additionally, GPRS was brought in to perform a pre-NASSCO inspection of the sewer mainlines and the sewer laterals, as well as a post inspection to make sure either companies didn’t hit any of the marked underground pipes. To perform these inspections, GPRS field personnel utilize lateral launch cameras, in order to help inspect those hard to reach, smaller pipes, granting a better perspective of the interior condition of the pipes.

First, how about we start with the pre-NASSCO inspection.

The National Association of Sewer Service Companies (NASSCO) sets industry standards for assessing, maintaining, and rehabilitating underground infrastructure. Because all GPRS Project Managers are NASSCO trained and certified, the pre-inspection allows our field personnel to provide NASSCO reports for the client with our findings. These standards allow our talented PMs to do a thorough inspection that covers all the basis for a sewer inspection. This includes the identification, evaluation, and management of pipeline conditions. Furthermore, GPRS’ post-pipe inspection includes a reevaluation of the pipe conditions to make sure the drilling company did not hit a line. We focus on this aspect because it’s well-known, especially in these particular jobs, that drilling companies make a mistake by drilling directly into a sanitary lateral (the pipe that leads to a buildings sewer and water system), which results in the toilets backing up. But even worse, if the company tries to fix their mistake (by utilizing a roto-rooter), they can mistakenly puncture a gas line, which releases natural gas into the pipeline system. Obviously, this creates one serious implication: when natural gas is leaked into neighborhood system, it could potentially blow up, endangering all individuals within the area.

Andy Jurski, a GPRS Project Manager, explains a situation that he came across emphasizing the importance of these inspections, including utility locating.

“I went out to a site that they did drilling on, without locating utilities, and they hit a storm line that was backing up to a hospital parking lot. We went from downstream to upstream, unpacked the debris from inside the line, and we could see the newly installed conduit positioned directly in the original line.” Jurski explains that this is a perfect example of why locating utilities and performing those pre and post inspections are so important. “Now, they have to dig up the entire road to this hospital, uprooting the area, just to fix that one line.”

However, there are more details that are involved when performing the post inspection on these video pipe inspection jobs.

For the post inspection, GPRS Project Managers will access the same point that was used for the pre-NASSCO examination, using the lateral launch camera, and recording the interior conditions of the line, making sure the directional drilling company did not cause any damage to the utility line. If there was damage to the utility line, during the process of drilling, PMs will further make surface markings to better pinpoint the underground utilities so no further damage can be done to that line. Now, these types of projects can become lengthy, depending on the focus area for any given job. For the job that Andy is currently working on, GPRS was hired to help locate and inspect all cross-bores for an entire town. This type of project typically takes months to perform, because all field personnel have to inspect every location where utility lines intersect. This cross-bore mitigation service can prevent gas line cross-bores and is critical to minimize the risk of property damage, injury, and even death. Even more, by performing these detailed inspections and locates, property owners prevent the risk of costly damages that not only derail a project timeline but can bring even more stress and heartache than was originally thought.

GPRS Video Pipe Inspection (VPI) is a service used to inspect underground water, sewer, and lateral pipelines. As we’ve seen, VPI is a great tool for investigating cross-bores as well as structural faults and damages and can be used for lateral line inspection.