Educate me about landscaping near septic systems (Raleigh: spring break, houses)

[NewUser]

My wife and I are looking at houses with large lots. As you can imagine, you have to head farther away from the city to find these, so the houses tend to have a community water well and individual septic systems.

Up in far north Raleigh (north of I540), the landscape tends to be more wooded and homes tend to have many trees on the lots. Down in far south Raleigh (below I40), the landscape tends to be more open and pasture-like, with very few trees on the lots.

I like the wooded feel of North Raleigh, but all the homes we've been looking at are in south Raleigh. Is it possible to plant a bunch of trees anywhere on a lot with a septic system, or do you have to stay clear of certain areas of the system (e.g., the leach field)?

Can you plant a garden off to the side of the system, or will your vegetables all end up tasting like sewage (yuuck!)? Can anyone recommend a good resource for what you can or cannot do with landscaping (or even hard-scaping such as decks, patios, etc) when you have a septic system in your backyard?

[toot68]

You are able to establish a drain field on a wooded lot. You'll likely need to clear out some brush and small trees. The home we've just purchased has one. There's a pipe sticking out of the ground, and we have to add a chemical to it a couple times a year to keep roots from encroaching.

[NewUser]

Originally Posted by toot68

You are able to establish a drain field on a wooded lot. You'll likely need to clear out some brush and small trees.

That's just what I was afraid of. If I start out with no trees at all and put in new landscaping, then for a number of years everything will be "brush and small trees". What is it about the brush and small trees that's a problem, but big trees are OK? This chemical that you put into the system sounds interesting. Almost like how my wife will put anchovies on her half of a pizza so I won't touch it

[alice_61]

It's best to plant grass over the drain field to promote evaporation and prevent root problems. You can plant trees off to the sides, though.

[toot68]

Granted my experience is only from our current house. The issue is roots encroaching on the drainfield plumbing. When you install the drainfield, you are digging out trenches for the plumbing and can work around existing trees, to some extent. You don't want to plant stuff that will be establishing root systems that can encroach on the plumbing, as they will lead to clogs that can result in your septic backing up. And given the chance, roots will encroach on the drain field, as it is a nice source of water, and thats what the roots are for

[NewUser]

Anyone else?

I understand that the roots want to get into the septic system, but I would think that a mature tree would want to get in just as bad as a new tree or shrub. In fact, a mature tree would have a much more extensive root system.

And how far away is "off to the sides"? Can you plant a tree 10 ft from the leach field? 50 ft? Does it depend on the type of tree (i.e, root system characteristics)?

[Kevin HW Engineer]

Originally Posted by NewUser

Can anyone recommend a good resource for what you can or cannot do with landscaping (or even hard-scaping such as decks, patios, etc) when you have a septic system in your backyard?

I do not have a septic system, however I would guess that you would want trees that do not have overly aggressive root systems.

I would suggest you contact a septic company or a good nursery for planting guidelines for trees that are not overly invasive. The septic guy will tell you what trees to avoid, whereas a good nursery will have an educated staff than can tell out about the aesthetics, growing requirements. Before I planted a sugar maple in my yard in Illinois, I had discovered that the particular variety should be planted at least 20 feet away fom foundations, in order to prevent the roots from busting through basement walls. We've all seen the giant trees that push up the sidewalks--granted in takes time. I realize that it may take decades for this to happen.
Pine trees seem to be safe-- I have seen some lots with pine trees that had blown down. If the roots aren't enough to keep it from blowing down, how invasive can the roots be?

On the other hand, how close do I want that type of tree next to my house?

Pet Peeve: I hate landscaping that is done for immediate impact, with little regard to what it will look like in the future. I used to have a landscaper live next door. His wife said that Bob always went for immediate impact,because otherwise customers wouln't think that he had done a good job ("it looks empty"). Future owners tore out 3/4 of what he had planted. Mostly fast growing junk trees for immediate impact. After he moved out, the cute little Christmas trees grew out into the driveway...no room for the kids to play in the back yard.

Still in Chicago...sigh.

Well actually today I'm in Raleigh. Spring Break. There were TWENTY SEVEN people on standby for the flight down.

[NewUser]

I found this on the North Carolina Department of Environment and Natural Resource's web site.

"Driving, paving, or building on top of a septic system can damage or destroy it. The pipes and septic tank can shift position or be crushed from repeated or even occasional abuse. Furthermore, the soil can be compacted, or ruts may form, exposing system components and possibly untreated sewage to the ground surface. Paving over all or a portion of the drainfield may prevent air from getting into the soil, as well as limit access for repairs or maintenance. Building over the drainfield may cause compaction or even damage a line due to the weight of the structure or the location of building footings. Paving or building over the septic tank also will prevent required tank maintenance.

Tree roots may clog the drain lines and gravel in the trenches. The best way to prevent this from occurring is to remove or simply not plant trees or shrubs within 25 feet of the drainfield. Roots may also get into the septic tank or distribution box, so do not plant trees and shrubs over these devices. You should plant grass over the drainfi eld and all other outdoor system components. The grass aids in removal of water and helps to prevent soil from eroding over the components.

Most septic systems require that an area be set aside for possible repairs. This area should be treated and protected just as if it were currently in use."

So, it sounds like you need to have a fairly big grassy area for a septic system.

[ducter]

Originally Posted by NewUser

I found this on the North Carolina Department of Environment and Natural Resource's web site.

"Driving, paving, or building on top of a septic system can damage or destroy it. The pipes and septic tank can shift position or be crushed from repeated or even occasional abuse. Furthermore, the soil can be compacted, or ruts may form, exposing system components and possibly untreated sewage to the ground surface. Paving over all or a portion of the drainfield may prevent air from getting into the soil, as well as limit access for repairs or maintenance. Building over the drainfield may cause compaction or even damage a line due to the weight of the structure or the location of building footings. Paving or building over the septic tank also will prevent required tank maintenance.

Tree roots may clog the drain lines and gravel in the trenches. The best way to prevent this from occurring is to remove or simply not plant trees or shrubs within 25 feet of the drainfield. Roots may also get into the septic tank or distribution box, so do not plant trees and shrubs over these devices. You should plant grass over the drainfi eld and all other outdoor system components. The grass aids in removal of water and helps to prevent soil from eroding over the components.

Most septic systems require that an area be set aside for possible repairs. This area should be treated and protected just as if it were currently in use."

So, it sounds like you need to have a fairly big grassy area for a septic system.

I have septic and seen some fail for different reasons. I would simply not risk planting trees close at all because it just aint worth the risk. It is too critical a system for your house.

[Kevin HW Engineer]

I met with a builder yesterday. He said that Hurrican Fran caused some septic fields to fail due to uprooted trees. I mentioned that I was under the impression that pine trees appeared likely to fall since their root systems appeared (to me) to be so shallow. He disagreed, and related seeing some pine trees bent over so far that their tips would be slapping against the ground, and that their failure mode was to have the top snapped off. I recalled seeing this in Charleston in 1989 (?) following a hurricane... looks like the Hand of God sliced them off...

The builder then related how oak trees can fall over and drag the whole rootball up with them, since the rain has saturated the ground... he had one tree fall over with a 30 foot rootball. The only way he could remove the tree was to spend a couple days burning off the rootball before anyone would be willing to haul out the log.