Tom Carpenter, executive director, Marquette Board of Light and Power

MARQUETTE — In an attempt to reduce a risk of potential outages for nearly 10,000 electric customers, the Marquette Board of Light and Power recently hired a consultant to evaluate the best route for a new internal electric distribution system and connection to the regional grid.

The BLP Board of Directors unanimously approved hiring GRP Engineering Inc. of Petoskey to conduct a transmission line route study for $29,000 during a meeting last week.

With the fairly recent idling of the Shiras Steam Plant in south Marquette, the substation at that location and the seven associated distribution feeders no longer have a redundant power source if transmission service were to be interrupted, BLP documents state.

In a letter from Ben Collins, manager of distribution engineering services, to BLP Executive Director Tom Carpenter, Collins said 9,500 customers are at risk of extended electrical service interruptions.

“BLP staff has worked with GRP Engineering to develop a non-transmission contingency plan for the emergency use if a transmission service interruption were to take place,” Collins’ letter states. “Such a plan, if implemented, will have significant system and customer impact; customers would experience at a minimum outages until back-feeds are established through the current distribution system.”

Carpenter said the study will help determine the best way to build a loop to a secondary emergency system.

In a letter to Collins, GRP President Michael McGeenhan said the study consists of expanding BLP transmission lines through either an internal 69 kilovolt loop or a second 69 kilovolt line into the system. The transmission line will support the existing distribution load at the Shiras substation.

“MBLP has established the need for a second transmission line following the decommissioning of the Shiras Steam Plant which left 5 Plant Substation on a radial transmission line,” McGeenhan’s letter reads.

The results of this study will determine the best route for the internal 69 kilovolt loop and the second 69 kilovolt transmission tie to American Transmission Co.’s electric transmission line.

McGeenhan said the transmission line siting process is typically a lengthy one involving local, state and federal agencies, private property owners, local organizations, engineering consultants, environmental reviews, public meetings and more.

“Additionally, the process can be controversial as electric transmission lines can be unwelcomed by property owners adjacent to line corridors,” his letter states. “Due to the need for this transmission line, the goal with this study is to establish a route which minimizes impact to these entities and expedites project completion.”

Transmission design standard to be used in the review will be traditional round wood or steel equivalent poles with line-post insulators.

McGeenhan said favorable routes include those with segments along established road rights-of-way, utility corridors or edges of open lands.

The process will include obtaining geographic information system, or GIS, map data from parcels, property owners, land use, rights-of-ways and soils, along with topographies, research of documented wetlands, protected habitats and state historical properties.

Second, for both the internal loop and new tie, the line connection and termination substation points will be determined.

Next, both GIS mapping and field reviews will be completed for possible route segments to identify potential development areas along each route.

Finally, routes will be selected by considering environmental and existing land uses, suitability for construction and total cost, which is currently unknown.

Board Director Robert Niemi said another study will be conducted once a route for the transmission line is determined.