To build up its federally required integrity management program for pipeline reliability and safety, utility provider Peoples Natural Gas (PNG) is replacing nearly a mile of 20-inch steel pipeline in Allegheny County, PA. PNG brought Wade Trim onto the project to provide survey, pipeline routing assistance, vertical design, environmental assessment, record drawings, and project management. Geotechnical and permitting subconsultants were added to the team to expedite the evaluation of installation alternatives.

The M-4220 Mansfield 20-inch-diameter replacement pipeline is routed across several streams and large, narrow ravines with major elevation changes. Sediment diversion control plans and pipe profiles were created to help protect steep slope stability and residential retaining walls up to 20 feet high. Bore Aid software used during the modeling and operational stress analyses helped the contractor determine that open cut installation would be more direct and cost effective than horizontal directional drilling. Design for replacement in the steep ravine considered numerous constructability factors that included trenching and trench stability, site restoration, and the use of prefabricated pipe sections to minimize in-ditch welding. We are also preparing the tie-in details and mechanical connections to existing stations.

Construction for the M-4220 replacement project is expected to be complete by fall of 2021. PNG’s Long Term Infrastructure Improvement Plan includes a significant increase in funding for integrity management improvements. Wade Trim will be assisting on additional projects in 2021, including a pipeline replacement in the “Yough South” area along the Youghiogheny River.