Repairing a Minnesota Mound - A Mound Septic System
Research and photos by Ken Connors of
Living on a farm or acreage in the Peace Country is a lot different than living in the City. One has to be more knowlegeable on how the waste is disposed because someday the septic system will need repair.

FAILURE: One of the signs of a mound failing after time, is that fluid starts coming to the surface. It could mean a couple of things. One of the pipes could be cracked from freezing, or compromised from heavy vehicles driving over it, or some of the pipes could be plugged from slugg causing an unbalanced pressure of disposal of fluid and an over saturation in one area. Also keep in mind that mounds do not last forever and eventually will not work properly from fluid build up within the crushed rock and sand below the pipes. If this is the case, then the rock and sand will have to be removed and replaced with new material. (19 year old mound repaired, 2014 Canadian price $3097: 1 day job with 2 workers, includes bobcat, labor, replacement pipes, and plastic tents. Crushed rock and dirt not included)

To help keep the pipes clear, they can be steamed out by a qualified technician if there are clean outs. If no clean outs are installed, then you will need a lot of luck trying to find the ends of the pipes by digging them out. As a preventative measure, the pipes could be steamed out every 3-5 years. (Check with your local company that pumps out septic tanks)

INFORMATION: Waste from home goes into an underground septic tank. Usually there are two chambers in the septic tank with a wall between them. Solids go into the first chamber and eventually break down and turn to liquid. The fluid will flow over the wall into the second chamber where it is automatically pumped to a mound or field. The 2nd chamber has a pump submersed at the bottom that has a float switch. Once a level is reached it will pump the fluid. The pipe from the septic tank to the mound is buried well below the frost line. Pumps in the septic tank can last 5-10 years or even longer and some of the better pumps can cost around $800 Canadian. The tank has to be pumped out to install the pump, an additional charge. (pictured right is an old pump that had failed)

CONSTRUCTION: A mound has a number of underground pipes connected to a manifold system.(refer to picture at top of this page) Usually there are 3 long pipes, each are the length of the mound. (some can be around 60 feet each) The pipes are perforated every 3 feet or so, allowing the fluid and sediment to come out. Usually the holes are at the bottom of the pipes but some installers will have them to the sides of the pipe thinking that this method will help prevent the holes from plugging. Many installers prefer to drill their own holes. The pipes can range from 1 1/2 -2 inches in diameter and come in 20 foot lengths. (2014 Canadian price, $50 each) The 3 pipes are installed so they are elevated a bit, so once the pump stops, any liquid still in the pipe can drain back to the manifold area, and back to the underground pipe that goes to the septic tank. This method prevents freezing.

The pipes are installed between 1 and 1/2 feet below the surface. Below the pipes there is about 4-6 inches of washed rock so it does not plug up the perforated pipe. Below that there should be a couple feet of sand to help handle disperse the waste (There are guidelines as to the proper amount of rock and sand, check with your local authority.) (2014 Canadian price: 13 cubic yards 3/4" Washed Rock priced at $400 plus $150 delivery. 10.35 cu yards Top Soil, $103 plus $150 delivery)

Some pipes were half clogged. This restricted sludge getting to perferateed holes
(enlarge photo)
Some pipes 100% clogged near the end of the line. System was compromised.
(enlarge photo)
Dug out pipes and gravel.Put in new washed rock and installed plastic tents over pipes
(enlarge photo)
More washed rock applied over the plastic tents to help hold them in place
(enlarge photo)
Landscape fabric was placed over area before dirt was applied to prevent plastic vents from plugging up (enlarge photo)
Top soil leveled and grass seeded and then watered each day.
(enlarge photo)

Research and photos by Ken Connors of All content is copyright ©