R. R. Branstrom | Daily Press A relief valve is shown at the Enbridge facility near Rapid River.

RAPID RIVER — One pumping station on Enbridge’s Line 5, which transports crude oil and natural gas liquids (NGLs) from Superior, Wisconsin to Sarnia, Ontario, operates on U.S. 41 just north of Rapid River. The main purpose of this site and others like it is to increase pressure to maintain the flow of liquids through the line as they make an eastward and southbound journey (across the U.P., through the Straits of Mackinac and down through the lower peninsula before crossing into Ontario north of Detroit), but it also serves to monitor conditions — measurements taken here are compared with other readings and used to identify anomalies. Upstream, the previous pumping station is in Ironwood; the next is in Manistique.

Enbridge, a Canadian company headquartered in Calgary, has the largest network of pipelines in North America and over 12,000 employees. Line 5, with its 645-mile span from Superior to Sarnia, is but a fraction of the company’s total portfolio. The line — owned, operated and maintained by Enbridge — serves as a carrying vessel, providing transport to clients who ship their products throughout the region. About 80 percent of the product moved annually is light, sweet crude oil, while about 20 percent is NGLs. Most of the route is serviced by a 30-inch underground pipe; the underwater section that lies on the bottom of the Straits of Mackinac is two 20-inch pipes.

Recently, the Daily Press took a tour of the Rapid River facility. It’s one point in the area of responsibility for those who work out of Enbridge’s Escanaba office; they maintain Line 5 from Ironwood in the western U.P. to just north of Gaylord below the bridge.

A lot of public attention has been focused on the straits area, especially after a dragging tugboat anchor damaged the submerged twin pipelines in 2018. Calls to action came from citizens, environmentalists, agencies and state representatives for new measures to prevent a leak into the Great Lakes. Former Governor Rick Snyder made an agreement with Enbridge for a tunnel to be built, funded by Enbridge. Current Governor Gretchen Whitmer ordered the line to be shut down, and Attorney General Dana Nessel sued the company when operation continued.

Now, the Enbridge Straits Maritime Operations Center (ESMOC) monitors the straits area around the clock from a station atop the former Mystery Spot on U.S. 2 just west of St. Ignace, utilizing methodology they have called “analogous to what government agencies do at ports and waterways throughout the world.”

High-resolution, infrared cameras in strategic positions above the water’s surface watch for approaching boats; there is radar for foggy weather; radios are used to communicate with boat captains; valves allow for flow stoppage; weather conditions are factored in; and hydrophones measure the severity of any collisions with the pipe and their location. Plans are underway to bore a tunnel deep under the straits to house a replacement pipe. Such secondary containment would allow for the new line’s access and maintenance, and transport through the existing pipes on the lake floor would cease. However, opponents argue that as long as there is oil and NGLs flowing under the straits, the Great Lakes will be in danger.

Tours of the ESMOC have been provided to the public and media outlets, and Enbridge runs an information center at a storefront in downtown St. Ignace so that they can address concerns people may have.

“We want to be as transparent as we can as an operator,” said Technical Services Supervisor Brian VanOss. “We have nothing to hide. We’re actually proud of everything that we do, and that’s why we’re open arms to anybody that wants to learn more about how we operate safely.”

Showing the Press Enbridge’s Rapid River pumping station, VanOss explained that the site was one of several that are located roughly every 50 or 60 miles along Line 5 as needed to optimize pressure. In hillier areas, pressure may need to be generated more frequently to push liquids upwards in elevation. Each of the facilities looks a little different.

This powerful station in Rapid, and Line 5 as a whole, pumps approximately 23.8 million gallons of product — whether NGL or oil, depending on the orders — through the lines each day. A hum of power reverberates through the property on U.S. 41, and in the pump room itself, earplugs must be worn.

Densitometers, thermometers, ultrasonic flow meters and more — with more than one of each in places, for redundancy’s sake — take measurements at the station. A material balance system in a computer reads the data, and if anything is abnormal, which could indicate a malfunction or leak, it triggers an alarm.

Some processes require no interaction. For example, inside the pumphouse, VanOss pointed to a a fully-automated pressure control valve that opens and closes, pinching the flow of liquid so as to not exceed the maximum allowable pressure, and called it “the most important valve in the station.”

Locally, employees may isolate and disengage certain functions. A human operator in Edmonton, Alberta, overseeing the readings across multiple Enbridge stations, can check on what’s being done in Rapid and communicate with staff.

Automatic emergency response protocols may also be triggered — for example, if one valve closes when it shouldn’t and too much pressure builds, a relief valve automatically opens when a certain PSI level is reached, diverting flow and alleviating pressure.

To prevent and mitigate accidents, a series of measures are in place. Cathodic protection prevents pipes from corroding until it’s time for sections to be replaced. Devices called “pigs” run through the interior of the line to check for anomalies and possible damage. A helicopter flies over the right-of-way of the underground Line 5 between stations every two weeks. If there is a report of a smell of gas or other suspicion that something may be amiss, operations halt and Enbridge looks into it, VanOss said: “Any emergency-type call, we shut down. Any abnormal condition, we shut down. We will always shut down and investigate.”

VanOss, who also serves on the Ensign Township Volunteer Fire Department, said that the department usually gets one or two calls per winter about a smell or possible leak in the area, but that the Rapid River Enbridge facility has never been to blame.

To prepare for potential incidents, periodic emergency response simulations are coordinated between Enbridge and bodies such as the Michigan Department of Great Lakes and Energy (EGLE), the Environmental Protection Agency (EPA), the Coast Guard and more.

On regular days, a software program generates work orders for technicians.

“When the technicians show up to work, they’ll open up (the program) and they’ll have a list of things to do,” VanOss explained. “It’s all behind-the-scenes generated, which is very nice. It’s a maintenance management program for day-to-day work.”

And there’s a lot to maintain and watch over. With its massive motors, cabinets of meters, dozens of valves, wall of computers and wires, the station is UPPCO’s single largest customer for electricity.

One unique thing about the Rapid River pumping station is that it’s not just one point on the line to propel product onward — it’s also an exit and entry point for one of Enbridge’s customers. The energy company Plains has a fractionation station right on the neighboring lot; many readers have likely seen the big white globe-like structure visible from U.S. 41 that belongs to Plains. When they receive an order of NGLs, it’s delivered by Enbridge via a pipe that diverts from their mainline. Plains boils the product to distill propane, which they then supply to consumers, and the leftover NGLs are returned to Enbridge through another line.

According to the U.S. Energy Information Administration, Michigan has more residential propane consumers than any other state. Enbridge’s pipes carry a large portion of the energy used and stored in Michigan — even at the end of Line 5 in Sarnia, some product is shipped back in.