February 12, 2018

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Pipeline Exposures at Waterbody Crossings: Assessment, Permitting Compliance, and Restoration

Performing appropriate environmental assessment, environmental permitting, geotechnical engineering, restoration design, and programmatic environmental compliance work are all important aspects of managing pipeline exposures around waterbody crossings.

A challenging component of this work is understanding and managing pipeline exposures for system integrity. Exposed pipelines have an increased potential for abrasion, corrosion, impact, and structural stresses that could compromise the safety and integrity of pipes. Maintenance and restoration work on pipeline exposures must therefore be planned, prioritized, coordinated with agencies, and implemented in compliance with environmental regulations utilizing sound engineering practices to ensure the safety and operational integrity of the pipeline.

Understanding the full cycle of pipeline exposure projects begins with the early planning and assessment phases, including geographic information systems (GIS)-based analysis of pipeline systems for predictive modeling of locations that may be at risk for pipeline exposure. Following this phase, field assessments of the pipeline system may be necessary to survey exposure locations. Surveys may include wetlands and waterbody delineations, geomorphological surveys, geohazards assessments, and natural resources assessments.

Exposed pipelines may be managed and mitigated by a variety of techniques, including: lowering the pipe in place, replacing by conventional trenching, replacing by horizontal directional drill (HDD), and protecting in place with engineered measures. Depending on the selected methods for restoring an exposure, further geotechnical and engineering feasibility assessment may be needed. This includes conducting geotechnical assessments and assessments of the engineering feasibility of HDD replacement designs.

Additional work may include preparing engineering restoration designs, including stream restoration designs, that incorporate measures to protect and stabilize the exposed pipeline while also sustainably addressing the geomorphology of the exposure area to help minimize the risk of future exposure. Stream restoration design may also be necessary for post-construction restoration where traditional pipeline lowering, or replacement is conducted.

As part of pipeline exposures program support, consider environmental permitting and compliance issues for exposure repairs and mitigation. This work may involve the preparation of environmental permit application packages for a variety of permits, including: National Pollutant Discharge Elimination System (NPDES) construction stormwater discharge permits, NPDES hydrostatic test wastewater discharge permits, Section 404 wetlands permitting, and Section 10 Navigable Waters permitting with the U.S. Army Corps of Engineers. Coordination with state and federal stakeholder agencies, such as the U.S. Fish and Wildlife Service, U.S. Forest Service, Federal Energy Regulatory Commission (FERC), relevant departments of transportation, state and municipal stormwater and floodplain managers, state and tribal historic preservation offices, and others as required. During construction, competent environmental inspection services should be used to comply with environmental permit conditions and provide compliance reporting and documentation for clients, as the lack of proper experience and oversight can lead to serious environmental, legal, and financial risks.

More Information

For more information, please contact Thomas Bristol at This email address is being protected from spambots. You need JavaScript enabled to view it..

Thomas Bristol is a Principal Engineer based in South Carolina with more than 17 years of experience in environmental consulting focused in the areas of environmental regulatory compliance; ecology and natural resources, and environmental assessment. Thomas is a senior leader in Geosyntec's Natural Gas practice group.

Learn more about Thomas Bristol: https://www.geosyntec.com/people/thomas-bristol