Sunoco Mariner East II – Spread 6 Trenchless Crossings

2021 Trenchless Technology Project of the Year New Installation Honorable Mention: Sunoco Mariner East II – Spread 6 Trenchless Crossings

In early 2019, Michels Corp. mobilized to the Sunoco Mariner East II (SMEII) Spread 6 Project to construct parallel 16- and 20-in. pipelines. The sites had major site constraints, heavily scrutinized environmental concerns, and problematic geotechnical formations. Michels, having a proven history of overcoming the many challenges associated with drilling in Pennsylvania, was tasked with completing the remaining 56 of the 66 rock crossings on the 30-mile spread.

Spread 6 stretches through highly populated areas in Chester and Delaware counties, west of Philadelphia. Drilling conditions included weathered gneiss rock mixed with quartz formations having moderate to high compressive strengths, potential for underwater aquafers, and compressed work areas sprinkled in residential and commercial neighborhoods making logistical challenges to maintain a supply of equipment and materials to work sites. The 56 crossings ranged in length to more than 7,000 ft, included tight horizonal and vertical combination bends, and site constraints required multiple sections for pipe pullback – all of which pushed the limits of industry standards. The Pennsylvania DEP designated some of the crossings to be redesigned due to fear of inadvertent returns (IR); requiring five to be completed using Direct Pipe, three with open-cut, and two with auger-boring methods. Michels worked to optimize the project schedule and increase the completion success by utilizing existing pilot holes and combining crossings; either increasing the crossing’s length or pulling both the 16- and 20-in. pipe through the same borehole. Initially Michels mobilized eight horizontal directional drill (HDD) rigs to complete several crossings that required the safe removal of tooling and the re-surveying of both pilot holes and/or partially reamed crossings. This effort led to Michels completing 18 crossings in 2019, 14 of which were previously abandoned at various phases of their operation. The outbreak of COVID-19 forced Michels to suspend work for a period in early 2020. When work resumed in late May 2020, Michels had mobilized 20 HDD rigs, including 16 custom, 1.25-million-lb rigs and two Direct Pipe spreads all of which worked toward a successful completion on SMEII Spread VI. Completing 26 additional crossings in 2020 and early 2021, Michels has installed nearly 65,000 ft of 16-in. pipe and 74,000 ft of 20-in. pipe using HDD and Direct Pipe methods on SMEII – Spread 6.

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Why Project is Outstanding:

Michels displayed comprehensive environmental stewardship. going to great lengths in the development and execution of an achievable drilling fluid management program. Michels limited the impact of construction noise by creative, strategic equipment setup, use of hospital grade mufflers and exhaust scrubbers, and/or 16-32-ft high sound barriers erected near engines and around the perimeter of sites in residential or businesses backyards. Michels respected local township noise ordnances by limiting crew hours of operation and site access to the hours of 9 am to 3 pm. Both required careful logistical planning and traffic control for critical materials, equipment and tooling. On several sites, two HDD rigs were set up back-to-back on an already limited worksite to drill in opposite directions. Most interestingly this took place between an active church parking lot and fuel station requiring extensive traffic control. Large diameter 36- and 60-in. casings were used to protect shallow utilities and preserve the borehole in soft formations. When required, nearly 6,000 ft of casing was pneumatically driven on both ends of a crossing’s profile till refusal; at depths up to 300 ft. Crossings required the pilot hole intersect method utilizing either magnetic tracking or gyroscope and precision drilling when negotiating several horizontal curves between 1,600-ft to 2,400-ft radii staying within tight ROW boundaries. Small exit site layouts forced multiple pull back sections significantly increasing risk; one crossing required 21 sections for a pullback lasting 10 days. Michels used the bundled dual pull method on three crossings 3,000 to 3,500 ft in length, by pulling both the 16- and 20-in. pipelines at the same time. Several pullback operations often occurred within the same month adding to the execution planning, including a time when three pipe pulls occurred simultaneously. Several crossings included elevation changes greater than 40 ft (including one more than 220 ft). Drill geometry and corresponding formation caused purged aquafers to flow out the borehole upward of 100 gpm. This water needed to be controlled both during drilling operation and off hours. The Direct Pipe drives featured diverse ground conditions from sands/clays to karst features with dolomite pinnacles. Constrained workspaces included working adjacent to a dentist office and in an apartment complex. One Direct Pipe crossing alignment even started at 0 degree and climbed 150 ft in elevation prior to terminating at an angle of 15 degree.

Project Owner: Sunoco/Energy Transfer

Engineer: Tetra Tech Rooney

Contractor: Michels Corp.

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