Horizontal Directional Drill (HDD) Designs

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PA Turnpike Crossing

  • Pipe Data: 8” Steel X-52
  • Challenge: Site constraints to crossing the PA turnpike include an adjacent bridge, a residential development that was under construction, and an existing easement proposed to be utilized.
  • Profile: Final drill design required entry and pullback to be located on the same side of the crossing to ensure pipe location met all requirements. Drill was designed with an additional mobilization to switch the drill rig to the exit side after the pilot hole was complete to provide proper pullback space.
  • Full Project Scope: Total project length was 18,848LF and included field survey, base plan development construction drawings, geotechnical investigation, HDD and pipe stress calculations, regulator station site design, environmental permitting, DOT permitting, and municipal permitting. Sub-consultants included local geotechnical engineering.

Interstate 81 Crossing

  • Pipe Data: 12”, 0,500” WT, ERW, API 5L GR X-52, PSL2, ARO & FBE
  • Challenge: Site constraints included an elevation change of over 100’ in a distance of 630’. Topography, as well as wetlands, and an existing quarry provided limited distance to obtain proper clearance beneath Interstate 81. Upon completion of an alternate analysis, and final crossing location selection, the engineering team worked closely with the contractor, and local geotechnical engineer to prepare a work plan, alignment, and profile that was vetted prior to permitting and construction start.
  • Profile: The 12” uncased pipe was successfully drilled at a 10° entry angle and 21° exit angle with zero makeup tangent and a bending radius of 800’.
  • Full Project Scope: Total project length was 4,300 linear feet and included environmental field work, environmental permitting with state and federal agencies for earth E&S, as well as an ACOE/DEP Joint Permit, State DOT coordination, design survey, alignment plans, construction plans, stakeout, as-built survey. A population density survey was also completed. Sub-consultants included local geotechnical engineering.

Susquehanna River/Norfolk Southern Rail Road & State Road 171

  • Pipe Data: 16”, 0,500” WT, ERW, API 5L GR X-65/X-70, PSL2, ARO & FBE
  • Challenge: Field route alignment to avoid Joint Permit due to agency review times exceeding project in-service dates. Alternate analysis provided a final alignment location that required back to back HDDs. The HDD alignments were faced with active quarry operations, active water withdrawal operations, Norfolk Southern Rail road, an old coal loading tower, the Susquehanna River, State Road 171, and significant surrounding topographic relief.
  • Profile: Final design consisted of two separate HDDs, joint with shared pullback space between them. The pullback space was optimized through use of dual pull back stages on the longer drill, as well and including a horizontal bend radius in the pullback zone. Significant depth was also added to the profile to guard against in-advertent returns within the river or water intake facility. A combination of wire, and wireless tracking systems were used for the HDD to prevent additional environmental permitting of a temporary wired system within the river.
  • Full Project Scope: Total project length was 18,480 linear feet and included environmental field work on multiple alignments, environmental permitting with state and federal agencies for earth E&S, State DOT coordination, design survey, alignment plans, construction plans, stakeout, as-built survey. A population density survey was also completed. Sub-consultants included local geotechnical engineering.

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