We discovered we have issues with our wastewater lateral and it needs to be replaced. Not to get too into the details but where we expected to find a 4” cast iron lateral that could be cleaned and lined we instead found a 6” terra cotta lateral with multiple issues that mainly stem from extensive root infiltration from the maple tree that was planted about 4 feet away from it.
The photo shows the tree and very close to where the line runs. The plan from our contractor is to dig up either side of the stairs and replace with PVC since lining isn’t possible. The excavation is planned to be only in the mulch beds shown, since the main runs in the grass about three feet away from the end of the bed. The existing terra cotta will be left under the stairs and to the main and lined then connected to the PVC.
Our concern is how close the excavation is to the tree and how it will impact the trees health. Ideally we would use trenchless but that isn’t really an option, and rerouting isn’t really possible due to needing to reuse the existing house and main connections. So what should I be sure our contractor is doing to best protect the tree, and how should we take care of it once everything is complete. We are expecting some die off in the canopy but it’s a really healthy tree so we are hoping that with good care we can save it overall.
When I was a kid, I remember we had a raspberry bush in the garden that suddenly started giving spectacular amounts of incredibly juicy raspberries. It did that for a couple of years, and then we started having problems with the septic tank. When my Dad dug it up to find out what was wrong, he discovered the raspberry bush’s root had reached into the tank and the bush was having a field day with the nutrients in there.
I suspect your tree is doing well for the same reason. If it got used to the land of plenty, it might suffer from being cut off of it.
Sorry I don’t have any particular advice to give you with respect to your problem though - apart from digging up the pipe with a shovel and trying to work around the tree’s roots, which is not something your contractor will be willing to do that is.
I’m not saying laterals have no nutrients, but the concentration and type of nutrients are very different between laterals and septic tanks.
Sewage in laterals is pretty dilute. Septic tanks (the tank, not the drain fields) are where the solids collect. They break down a bit over time and particulate forms of nutrients become soluble and more easily taken up by plants.
The sewage in the fields is also generally more strong than sewage that goes to municipal or shared systems because it’s passing though the tank and taking up some of those newly solubilized nutrients on the way to the field.
The tree is absolutely going to get less water when it’s repaired, but I’d be doubtful that the nutrient level will change all that much.
I hadn’t considered this. I imagine soaps and such also don’t help things in a lateral since a lot of the water will have some sort of soap in it (anything other than a toilet flush, and those will be followed by at least a small amount from hand washing).
Maybe it’s because there’s always some water being pumped into a field, but the grass always grows like hell on a field. Effluent will also have quite a bit of nitrogen because urine=urea.
Yeah, I’ve had that same thought. About 30 linear feet of 6” pipe chock full of tree roots tells me it’s been feeding on that buffet for a little while. That said we live in an area where trees do really well anyways, there’s another tree about 20 feet away that’s also does fantastic and it’s not even close to anything as great as a sewer pipe so I do have hope that after a year or two it will bounce back, but it looks like we will end up cutting around 1/4 to 1/3 of its roots out. Luckily the house blocks the predominant wind and the hill slopes away from the house so worst case it shouldn’t be a risk to the house.
This happened when I was a kid as well, also terracotta, but the tree was a cedar, my father did exactly what you plan to do and the tree wasn’t the same after, but did live. Maples are top feeders(?) and compete with the grass for nutrients AFAIK, so probably will be rather hard on it. My arborist came out for free and took an hour talking about each of the trees in the property before his crew came out to do trimming and take one down, I’d assume that’s common practice, so I’d get a pro out and get their advice. Good luck.
Interesting, about 3/4 of the drip area is mulched with very few plants in it and honestly the grass doesn’t do great under the canopy so maybe it won’t need to compete as hard. I’ll have to see if I can get our borough tree guy to take a look at it, otherwise I’ll need to find a tree company near us.