Drilling Through 42,000 Feet of Granite to Protect a National Treasure

By replacing failing septic tanks with a sanitary sewer system, a collaborative team is helping protect the only water-based national park in the country.

During an era of toxic algae blooms and tightening nutrient regulations, a forward-looking committee of counties, sanitary districts and concerned citizens continue to take preventative measures to protect one of the world’s most precious waterways.

After a few successful projects, the next step involves replacing an aging septic system with an innovative sewer system. The process requires drilling through approximately 42,000 feet — nearly eight miles — of granite bedrock.

Clear lakes, rocky islands, and tall pine shorelines define Voyageurs National Park, situated along the border between Canada and Minnesota.

Protecting the only water-based national park

Deep in northern Minnesota, along the United States-Canada border, sits the nation’s only water-based national park. Called Voyageurs National Park, its 84,000 acres of water and 134,000 acres of land provide visitors a one-of-a-kind opportunity to explore the north woods lake country.

For years, those pristine waters have been surrounded by hundreds of septic tanks used by property owners. However, due to the age, difficult topography, high bedrock, and high water table, those septic tanks are failing at an alarming rate. Leaking sewage poses a significant threat to the area — not only to the long-term health of the natural ecosystem, but also to an economy sustained in part by a thriving tourism industry.

To solve this challenge, a group of concerned stakeholders joined forces in 2010, calling their collaboration The Voyageurs National Park Clean Water Joint Powers Board. The Clean Water Joint Powers Board was set up to help project partners develop a comprehensive wastewater collection and treatment system for the housing, recreational, and resort developments in the Park’s Namakan Basin area.

To date, two planned projects have been completed and another is currently under construction. The next project, Island View Sanitary Sewer project, is the biggest and most technically challenging.

Drilling through eight miles of solid granite bedrock

“This is the reason why I became a civil engineer,” says SEH’s Randy Jenniges, PE, the design engineer leading the SEH team (listed at bottom) working on the massive task. “To work on projects like this that are technically challenging, and important for the well-being of one of the most important waterways of our area.”

The Island View Sanitary Sewer project includes extending sewer service to about 300 residential properties and eight commercial establishments.

“In concept, it’s lake sewering 101. In practice, however, it’s extremely complex,” says Jenniges.

What makes the area so unique—its beautiful rock formations—also creates a unique challenge. The area’s shallow bedrock prevents applying any typical engineering solutions.

How the sewer system works. A typical city system uses gravity. Pipes exit your home and carry sewage downward. Gravity brings your sewage to the treatment plant. For residents near Voyageur’s National Park, gravity is not an option. Try to dig more than a few inches below the ground in the project area and you hit bedrock. The engineering team had to design a system that uses a combination of grinder stations (small pumps at each house) and small diameter pipes, which by virtue of their size create the necessary pressure to send sewage from residences to the main line, then off to the nearest wastewater treatment plant, 15 miles away.

Next steps

The Island View Sanitary Sewer project will be bid in the fall of 2016, with plans to build in 2017.

What about the rest of the lakes in the Land of 10,000 Lakes?

The Minnesota Pollution Control Agency, which is currently working to identify the effects of aging septic systems, estimates one in every five septic systems, for a total 500,000 tanks in the state, is failing.

“An ounce of prevention is worth a pound of cure. When we wait too long to take on projects like these they become headlines, for all the wrong reasons,” says Jenniges. “Look around the state, and you’ll find that we need the kind of proactive care and attention being carried out by this group [Voyageurs National Park Clean Water Joint Powers Board]. As an engineer, it’s a true honor to be part of this team, this difference-making project.”

For more information about this project, email Randy Jenniges.

This project was recently featured on MPR.org.

About the SEH Team

Sara Christenson, EIT, helped with the Joint Powers Board.

Colin Marcusen, PE, served as project manager for the Kabetogama project.

David Blommel, PE, served as project engineer for the collection system of the Kabetogama project.

Bryan Remer, PE, served as project engineer for Island View project.

Mike Larson worked extensively to help get funding necessary for the project.

About the Expert

Randy Jenniges

Randy Jenniges, PE, is a civil engineer, SEH Principal and project manager, and life-long advocate for clean water. Contact Randy

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