Trenchless Technology Game Changers: LT Directional

LT Directional

On a rainy week in San Mateo, California, LT Directional was up against some mighty odds. Not only was mother nature on their tails with some major rains threatening the productivity of the job, but they also were in a metropolitan area that put them up against public transportation railway on the surface, as well as the risk and hazards that come with drilling next to that–but they also we battling an especially complex maze of existing underground utility under the surface.

With some major high-tech companies headquartered in neighboring streets, such as Survey Monkey, Sony Interactive, and GoPro, they had a lot to lose if they inadvertently hit some existing power or communication utility lines. The safety of the crew was paramount from minute one as we arrived on the scene at 6 am, ready for the safety briefing. The job was to install 27 2-inch pipes over a few hundred feet that paralleled the San Mateo rail. This meant that there were a few different factors to take into consideration for the job.

Bore Hole Size

First, LT directional would need to widen the hole enough to provide enough clearance for a 27-way puller. This meant that the final hole size would need to be at least 32 inches in diameter. With 27 2-inch pipes, the hole would need to be large enough that there is clearance for the pipes to pull freely without creating a suction that often accompanies the deadly combination of too little clearance in a whole with not the right mud recipe. When you create a hole that large in the shale, clay, and sand composite mixture that you often find in Northern California, suddenly, the wall pack becomes a concern as well…which leads to the next factor.

Hole Stability

With a 32” hole, there is a lot of room for gravity to take over, and the hole collapse in on itself or deforms. They opted for the Deluxe Barrel, or “pig,” from Melfred Borzall with added hardfacing, mudflow ports, and cutter teeth options. 

HDD Tooling

LT Directional knew they needed tooling custom-fit to this large bore tooling that was not quite Maxi but larger than typical jobs. The tools they decided to include in their arsenal were a 32” Deluxe Barrel & Tornado Reamer combo for mixing and pumping action that simultaneously provided wall-pack stability. Running a JT100, this crew encountered rocky conditions but ample amounts of sandy conditions that risk collapsing the hole. The Tornado’s large paddle cutter blades provide the mixing action needed to keep the risk low for balling up. The barrel stabilizer also kept fluid flowing with its built-in fluid ports.

They trailed that with a swivel and custom-manufactured multi-duct puller from the Melfred Borzall engineering team. The multi-duct puller had 27 eyes that connected to 27 DCD Deluxe Duct Pullers that protected the pipe ends with a bell. 

Melfred Borzall engineers had a challenge ahead of them as they had to build this from scratch and tailor it to the specs of LT Directional’s job. After sharing designs, collaborating, and finalizing the puller, it was tested and delivered on-site by their Northern California HDD specialist.

This was a great example of careful planning, proper preparation and investment in the right areas to ensure a successful job…even when mother nature isn’t cooperating with the job.