Wednesday, October 26, 2011

Septic Leach Field, and Garden Woes

Damn and Double-Damn!! Seems I've discovered a potential minefield with moving my garden area higher up from the creek, which puts it closer and downhill from our septic tank and leach-field system. Frankly, I hadn't given the septic system any thought until now.

In my process of sheet-mulching a large area for a new garden, last weekend I started also considering the addition of 2-3 small sheet-composted areas nearby as prep for planting a couple of fruit or shade trees in the spring. Now I find that would put the trees smack-dab in the approximate area of either the tank, the leach-field, or both. You are not supposed to plant trees over the septic area because the tree roots can invade and damage the system.

According to everything I read online, eating foods (including tree fruits) grown over a leach field or just downhill from it, could be hazardous to health. That's a very scary thought!

I did find the diagram for the septic system permit in our house closing papers, and it's rather vague about exact location. That hasn't bothered me until now, but in considering what kind of trees to plant, or where to plant vegetables, the location IS of utmost importance. 

The tank hasn't been pumped in years as far as I know, and certainly not in the 5 years we've been here. It needs pumping now, and a pump tanker can't get under our low-clearance covered bridge over the creek. The tanker will have to come across the neighbor's field, and I'll have to take down a section of fence. The tanker also will probably have to drive over the fragile leach field to get to the tank too, unless they have a very long hose.

The other disturbing thing I found out is the expected life of a leach field... which with the best maintenance is around 20-25 years. Years ago most leach firlds used small sections of terra cotta pipe, which have a very long life expectancy if tree roots don't get in them. More recently, most leach fields use cheaper perforated plastic pipe, which can silt up.

Our system was installed in 1986, exactly 25 years ago, and surely has perforated plastic pipe. Not knowing the exact location and extent of the leach area, the huge area where I recently added a foot of compost and berms could be over part of the leach field!

Unfortunately, the only somewhat level area on our property for a veggie garden of any kind is on the side of the house with the septic system. The septic tank appears to be above any potential garden area, so it would all percolate downhill.

I have someone from Environmental Health coming out this week to assess the situation. No doubt I'll then need to hire someone to locate the tank, bring in heavy equipment to dig up the lid, and a tanker to pump it out. We won't be able to even assess the leach field until we can measure the scum layer and the sludge layer inside the tank.

I am NOT a Happy Gardener!


  1. We had a garden over top of septic tiles at our old place. You can't plant anything with long roots, like rhubarb, but everything else was fine. It should be buried a couple of feet, plenty of room to run a tiller over it. Everything grew great there, and it was pretty much self watering.

    The lid shouldn't be that deep either, and they're generally small, so they can be lifted without equipment. The trick will be finding it.

    Good luck!

  2. Oh, man. I *so* feel your pain! The sunniest and largest area of our yard is where the leach field is located. My gardens are only a few feet away from the tank.

    I thought about putting raised beds on top of the leach field, but after doing some reading, decided not to. The literature I read talked about drainage issues with adding dirt on top of the leach bed. Anyway.

    I will still use container gardens, on the leach bed ;).

  3. We went through the whole find the tank and replace the drain field several years ago. Oh joy. Our house was built in 1982. We have many oak trees right on the edge of the drain field. We have houses in the area that don't have trees near their drain field that still have the original drain field. If your drain field is failing, you will have sewage water backing up into your house. The tank fills up because it can't empty into the drain field because the drain field is overloaded.

    You could probably find your septic lid yourself by following along the sewage out pipe with a piece of 1/2" metal rod and sticking it into the ground till you hit the concrete lid. Or, look for a spot where nothing will grow well. The lid is about 24" diameter at the most, with metal handles.

    The folks who did our drain field were very talkative and educational. A few tips for extending the life of your pvc pipe based drain field include: give your drain field a long break between heavy water using devices. For example, don't do back to back wash loads and run the dishwasher at the same time. Keep all chemicals out of the drain field. Use septic tank plain jane single ply white toilet paper. Don't use a garbage disposal.

    The drain field crew found our drain field by walking around poking long rods in the ground. I don't know exactly what they were probing for though. Maybe hitting plastic pipe? Or maybe you could use a water witching rod.

    Hope this helps a little bit. Good luck.


  4. Thanks, I know lots of folks have gone through this.
    There is a capsule they can flush, magnetic or something they can detect once it's in the tank. $$$$$$, I'm sure!

  5. I'd be tempted to abandon the septic system then start a grey water line and a redworm fueled outhouse.

  6. Dennis, I AM sorely tempted, at least the greywater part... and I'm actually working on it. The septic is another matter, largely due to my neighborhood. My sister would never use an outhouse, and the neighbors would turn me in!


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