SEMCO is constructing and operating approximately 43 miles of new natural gas pipeline. GEI assisted with the route optimization, environmental permitting, and the Horizontal Direction Drill (HDD) design for crossing below six major rivers.
The new project is referred to as the Marquette Connector Pipeline Project (MCPP). The MCPP consists of the construction of approximately 43 miles of 20-inch diameter and 10-inch diameter mainline natural gas pipelines. The proposed pipelines extend in a northerly direction from existing natural gas transmission pipelines located near Arnold, Michigan to an existing natural gas interconnect in Negaunee Township, Michigan and to an existing distribution system in Marquette, Michigan. The project is being constructed to increase natural gas supply reliability to SEMCO’s customers in the central and western Upper Peninsula, and provides much-needed redundancy in the event of supply disruption.
At the onset of the project, GEI worked closely with SEMCO staff to perform a constructability review of the proposed 43-mile route. GEI partnered with a large natural gas pipeline construction firm to assist with the review and optimization of the pipeline alignment. Part of the alignment optimization included minimization of impact to environmentally sensitive areas to the greatest extent possible. GEI completed a DEQ/USACE Joint Permit Application for the proposed pipeline.
Along the proposed 43-mile pipeline corridor, there are six major river crossings that will require crossing. GEI evaluated the suitability of utilizing HDD at the river crossings and developed a geotechnical exploration program to support the design of the crossings. The geotechnical exploration was completed in challenging field locations requiring remote access through large forested wetlands and into steep ravines. GEI obtained a permit from the Michigan DEQ to conduct the soil borings within wetlands. The geotechnical exploration program was completed and supplemental laboratory testing was performed in the GEI Marquette lab, including compressive strength testing on rock cores. GEI utilized the results of the exploration work and subsequent laboratory testing program to develop the geologic profiles for the HDD design work.
GEI utilized Vermeer BoreAid software to assist with the design of the HDD crossings. The design was conducted to evaluate the installation and operational pipe stresses, and to compute the drilling fluid pressures for assessing the potential for inadvertent drilling fluid returns and releases (frac-out).