Building a Better Septic System

  • Researcher Barb McCarthy inspects a container of peat used to treat household wastewater. She says peat is very good at removing pathogens.

In many places around the Great Lakes, people depend on on-site septic systems to handle their household wastewater. The number is growing as people move to rural areas and retire to lake cabins. Health officials say too many systems aren’t working properly, and are polluting wells, lakes and rivers. Now, people are beginning to experiment with new kinds of septic systems that might work better than the traditional trench system. The Great Lakes Radio Consortium’s Stephanie Hemphill reports:

Transcript

In many places around the Great Lakes, people depend on on-site septic systems to handle their household wastewater. The number is growing as people move to rural areas and retire to lake cabins. Health officials say too many systems aren’t working properly, and are polluting wells, lakes and rivers. Now, people are beginning to experiment with new kinds of septic systems that might work better than the traditional trench system. The Great Lakes Radio Consortium’s Stephanie Hemphill reports:

Not everyone lives on a sewer line, and people who don’t, need to treat the waste from their toilets, showers, and washing machines right where they live. More than a quarter of new homes are built with septic systems in their backyards.

Conventional septic setups start with a tank, where solids settle to the bottom and get pumped out every few years. The liquid flows to a leaching field, where it percolates through soil. Organisms in the soil absorb pathogens, and the wastewater is supposed to be clean by the time it reaches the groundwater.

In northeastern Minnesota, the theory bumps up against the reality of the region’s geology. Health officials in St. Louis County, near Lake Superior, say as many as three-fourths of the septic systems aren’t working properly.

The trouble is, in many places here, there’s hardly any soil. You often stand on bedrock. What soil there is tends to be heavy clay, which won’t easily allow water to percolate through it. And the many lakes and rivers mean the groundwater can be just a few inches below the surface.

Researchers at the Natural Resources Research Institute in Duluth are testing several experimental systems.

“The module peat filters are ones that people are kind of using a lot in this area.”

The NRRI’s Barb McCarthy says a modular peat filter – self-contained in a plastic tub about the size of a refrigerator – can clean up the wastewater generated by one or two people. She says peat is very good at removing pathogens in the waste.

“And we think that part of that is because of the biological community that you find in a peat filter, it’s probably dominated more by the fungi and those type of organisms.”

McCarthy says they’ve seen everything from worms to frogs living in the peat filters.

Dan Karban installed a peat system when he built a house on Wild Rice Lake north of Duluth. Karban says he decided against a traditional septic system.

“All I heard was they might work, they might not work. So they were really subject to fail. And I didn’t want that. So I was willing to spend the extra money to get something that I felt was going to not only last longer but also look more appealing on our land site here.”

The tubs of peat are buried in the ground. As the water works its way through the peat filter, the organisms clean it up. Then it’s pumped to a leaching field, which looks just like the rest of the yard.

Karban paid about twice as much for the peat system as he would have for a traditional system, but he’s delighted with the way it’s practically invisible in his yard. And it even warns him, with beepers and lights, when he’s got a problem.

“Was it last spring we had all the rain and we had alarms going off everywhere, because the leaching field was so saturated with water that it wasn’t taking any more water. It was telling the pumps not to pump any more water. So we needed to cut back on our water usage.”

In a traditional septic system, there would be no warning – your nose would tell you when the trenches were too full.

More and more people are deciding to live at the lake instead of just visiting on weekends. At Grand Lake north of Duluth, people have converted a lot of cabins to year-round homes. Their sewage was feeding the algae and the lake was turning green.

“If you want to keep your lake, we found out from the other lakes around here that the overload is just too much and everything blooms in the summer. The lake becomes un-useable in the nicest months of the year.”

Gene Curnow and his neighbors got together and built a wetland to handle their wastewater.

Each house has a tank for the solids. Pumps send the liquids to the wetland, built away from the lake. Bacteria among the roots of the plants break down the pathogens in the water. Curnow says the lake has been cleaner since they built the wetland.

“The nutrients are not getting into the lake like they were. And that’s what this does, it brings the nutrients out here and lets the plants eat them.”

People in Scandanavia have been treating their household sewage with constructed wetlands and peat filters for years. But rules in Minnesota and most other states aren’t set up to permit them. Health officials in northeastern Minnesota are working on changing the rules.

For the Great Lakes Radio Consortium, I’m Stephanie Hemphill in Duluth.