In Minnesota, one of the biggest complaints we hear from homeowners is: “I need a new septic system; do I have to have one of those systems that ends up looking like a big pile of dirt in my yard?”
As we travel around the country, this question or complaint is worded a little differently, but it remains an issue that causes homeowners a lot of anxiety. They want to know, after all the equipment leaves, what their yard is going to look like. In Minnesota, this often comes about because of our high percentage of soils with high water tables. The result is a large number of above-ground at-grade and mound systems. In other situations, homeowners wonder if they can preserve elements of their landscaping, such as flowerbeds, trees or shrubs.
The installer who knows how to deal with these questions and has an understanding of landscaping concepts will have a leg up on competitors who just want to plop a system on the lot and do a minimal amount of grading to smooth things out, then be on their way. As always, the best way to have a happy repeat customer who recommends you to others is effective communication at every stage of an installation and going forward.
VEGETATIVE COVER
In humid areas, one important aspect of a properly functioning soil treatment area is establishing good vegetative cover. This is true for belowground or above-ground systems. Having a good, solid well-maintained cover keeps soil from eroding, allows the vegetation to remove moisture and nutrients from the soil, provides an insulating layer and makes the area more aesthetically pleasing.
Planting the wrong vegetation can cause irreparable damage to the system, so it is key to know the best types of ground cover for your area. Trees, shrubs and any herbaceous plants that have extensive root systems should not be placed on top of or near the system. In general herbaceous plants such as turf grasses, wildflowers and native grasses are suitable for cover. The University of Minnesota offers a listing of plants suitable for system cover found on their website, www.septic.umn.edu.
Turf grasses are probably most often used. They have fibrous root systems that hold the soil in place, and many varieties are available, from shade-tolerant to those that can take more sun and dryness. Choosing varieties that fit the site is important. Homeowners should be aware that turf grasses require regular lawn maintenance, so if the homeowner does not want to be fertilizing, watering, etc., use of native grasses or wildflowers may be a good option.
Native grasses and wildflowers are attractive alternatives and provide the same functions as turf grasses without some of the maintenance. Native vegetation is usually more drought-tolerant which is good from two perspectives. First, the vegetation can survive better during dry periods without watering over the top of the system, and since they are drought-tolerant, the native plantings are less likely to aggressively search for water contained in the system. That means fewer problems due to root penetration.
With any groundcover solution, it’s important to limit the traffic over the systems during planting and to avoid methods of preparation that cause soil compaction problems now or maintenance issues due to working the soil later. Compaction will limit the soil’s ability to conduct water and oxygen around the system.
OPTIONAL SHAPES
One of the chief complaints with above-ground mounds and at-grades, particularly on nearly level lots, is that homeowners end up with a 3- to 4-foot-high rectangular-looking lump in the middle of their yards … with a bunch of white pipes sticking out. When installers hear this complaint, they can present options for system placement and the final shape of the system.
Suggestions can include changing the shape or orientation of the system if the topography allows, transforming that pile of dirt into a privacy barrier, windbreak, landscape focus or a screen to block off views from the road. Here you may need to work with the designer and the homeowner so there is agreement about the placement and that it fits with the site constraints.
On sloping sites, it’s often more feasible to fit the mound or at-grade into the landscape, reducing the profile and resulting in a different shape. The system needs to line up or be installed on the contour, providing an opportunity to add additional fill to blend it in with natural landscape features. This reduces the profile and makes the slope smoother and more gradual. Fill used to blend the system into the landscape should be clean and suitable for establishing vegetation. However, since it is not part of the treatment component, it does not have to be clean sand.
A couple of notes: Fill placed over the top of the mound or at-grade should not be more than 30 inches deep to maintain good moisture and oxygen exchange. Trees the homeowner wants to keep – either upslope or downslope from the actual treatment area – can be left in place. However, if the fill to finish off the shape of the system will be in contact with the trees, a rock well or landscape feature must be incorporated so the soil doesn’t contact the tree bark. This contact will result in a fungus that will begin to attack the tree, ultimately killing it. The installer may be long gone at this point because that process may take a couple of years, but the homeowner is not going to be happy.
Native vegetation on a mound or at-grade system requires little maintenance, simple regular checks every few months for disruptive burrowing animals, which should be removed. In any system where the grass is not regularly mowed, this is probably a good recommendation.
Next month we will continue on the landscape theme and look at some specific planting techniques and tips.
