Michels established yet another North American record in the underground construction industry, this time by successfully pushing the limits in an emerging trenchless technology called Direct Pipe (DP). Michels installed a 48-in. diameter steel pipe an astonishing 4,038 ft in Freeport, Texas.
The project had been designed and attempted as two separate horizontal directional drills (HDD) by another contractor for a 16-in. pipeline, but an alternative method was found to be imperative to meet stringent U.S. Army Corps of Engineers’ (USACE) environmental and technical requirements for drilling beneath a levee at the location.
The installation crossed under the Dow Barge Canal, several roads, a rail track and USACE flood control levee governed by requirements for minimizing downhole annular fluid pressure. Instead of installing two HDDs, Michels suggested a single Direct Pipe installation using a steel casing pipe to significantly lower annular fluid pressure through critical monitoring zones starting 300 ft on either side of levee toes to meet the USACE requirements. Michels used the original approved HDD designs as a basis and re-designed the launch area and beginning of the drill to avoid the maze of utilities and to ensure anchoring feasibility and ability to withstand the stress and rigors of pipe thrusting from an earthen reinforced pit without damaging nearby utilities.
Michels used a Herrenknecht 750-ton pipe thruster and tunnel boring machine attached to the head of the pipe to guide it along the alignment. The spoils and drilling fluid were removed through supply lines inside the casing pipe leading to a separation plant at the surface. The fluid was recycled for reuse.
Because this project was the critical last piece in Phillips 66’s Sweeny Midstream Pipeline, Michels team made sure to have ample personnel and equipment on hand to safely and efficiently conduct operations 24/7. Michels also developed a detailed drilling fluid management plan to contend with challenging soils in the pre-determined elevation and to allow for the cutterhead’s efficient operation. Michels used a combination of the manufacturer’s monitoring system and a series of redundant checks to ensure accurate navigation along a route that contained challenging angles and complex curves. After the DP casing was installed, Michels utilized an HDD rig and same crew to install the 16-in. product pipe inside the casing. Michels also completed two shorter DP installations on the project.
The Dow Barge Canal crossing was the longest Direct Pipe installation completed in North America, eclipsing the previous record established just weeks prior by 500 ft. Completing a 48-in. installation of almost three-quarters of a mile is a significant achievement for DP. However, further challenges that had to be overcome by the Michels DP team made it an exceptional one.
One of the greatest issues posed by record-length trenchless crossings is the lack of prior similar efforts to base planning and contingencies on. However, the conviction of the owner and experience of the contractors propelled the project through extremely difficult conditions, including extreme duress and sweltering heat reaching 100 degrees daily and up to 120 degrees inside the pipe. This required the DP team to push the envelope with tooling and technology while maintaining strict safety precautions. The team was up against a critical path deadline that was quickly coming due while progression of the pipe slowed right when the light was seen at the end of the tunnel. To re-establish efficient mining, the DP team combined ingenuity with fearlessness for trying new and undeveloped methods, techniques and tooling and Michels’ equipment resources to provide enough power to propel the enormous pipe string to the finish. Meeting this deadline once again demonstrated Michels’ ability to maximize the possibilities of established and emerging trenchless technologies.
Because the project was originally designed as an HDD, the profile had already been approved and permitted. To comply with the timeline, Michels adhered to that profile rather than encounter substantial delays for re-design and re-permitting.
Michels has upped the ante on the types of projects that are possible using DP methodology. Being able to safely construct utilities in areas where it would previously have been impossible (e.g. highly sensitive levees) allows customers to plan more direct alignments that will ultimately lower costs and improve service.
Due to the length, location and general nature of construction, safety was a major concern for Phillips66 and Michels. The completion of this project without injury is a true testament to Michels’ HSE commitment. Michels mitigated safety risks with daily safety briefings and extensive training.
This crossing will long be remembered as a significant milestone opening the door for longer length DP installations.