Question:
Has anyone had trouble with root intrusion in drainfields that use chambers?
Answers:
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I live in California where it never rains. I say this because the trees around here are looking for water, any water, all the water they can find. In the 1930s, the Civilian Conservation Corps planted a lot of Eucalyptus trees — the trees from hell when it comes to roots. I have seen rock systems so impacted with roots that the perc was non-existent.
What we do is install chambers with rock salt around the inlet — the only area I believe to be vulnerable. Yes, the roots will come back, but the cavity so far has not filled to the point of plugging.
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I have always liked chambers, and as far as root penetration goes, it would make sense that if the narrow openings are protected from being plugged, root penetration may even be beneficial by taking up effluent.
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Roots look for water. If the pipes drain after each dose, there will not be standing water for them. Also, if your application rate is well below the acceptance rate of the soil, the soil will be unsaturated, making it quite difficult for the roots to pull the water away from the soil (wilting point). I would suggest installing a control panel with an ETM and event counter, then measure the time it takes the new drainfield pump to deliver a dose. In the future, you will be able to tell if clogging is a problem because the drainfield pump will require more time to deliver the same dose.
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I put a system in last year where there were many weeping willow trees, and I had some concern. Of course, the customer didn’t want to hear it, so I put it in anyway. I’ve done some repairs where the roots took over in a pipe- and-stone system. I tried a chemical treatment, and it seems to have worked very well so far. I hate using chemicals, but the customer didn’t have a lot of money, so the customer comes first, right?
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All the rules and regulations regarding septic treatment are designed to protect the groundwater, so using chemicals seems counterproductive. That is not to say I have a good alternative; this is just an observation. Here in the desert, we don’t run into that type of problem, so I have zero experience with combating roots.
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For root control, you might want to try Treflan, an herbicide manufactured by the Dow Chemical Co. Its main purpose is weed control, but it is also a valuable tool for root intrusion and is used by Geoflow drip irrigation under the trade name ROOTGUARD. It comes in liquid and granular form. You would have to check with the manufacturer for rates. It is safe for water supplies.
