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 significant 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 were battling an incredibly complex maze of existing underground utilities 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 crew’s safety was paramount from minute one as they arrived on the scene at 6 a.m., 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 there were a few different factors to consider 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 for clearance for the pipes to pull freely without creating a suction that often accompanies the deadly combination of too little clearance in a hole with an incorrect 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-inch hole, there is a lot of room for gravity to take over, and the hole can collapse in on itself or deform. The crew 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-inch Deluxe Barrel and Tornado Reamer combo for mixing and pumping action that simultaneously provided wall-pack stability. 

Running a JT100 directional drill, 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.

The crew trailed that with a swivel and custom-manufactured multiduct puller from the Melfred Borzall engineering team. The multiduct 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 wasn’t cooperating with the job.

Melfred Borzall has developed HDD tools to make directional drilling more productive and more profitable for 75 years. The company’s Southern California design and manufacturing plant is ground zero for the HDD tools that changed the way an entire industry drills.

800-558-7500 or 805-739-0118 (outside U.S.) www.melfredborzall.com