Grading/Drainage near septic tank/field
Hello,
My backyard generally slopes toward my house, most of that backyard is also my septic field. The grade is also currently above the top of my foundation and up against my sill plate(and whatever you call the board on top of the sill plate). This situation is resulting in that wood rotting, some plant life growing literally into my basement, and I’m sure it’s also contributing to insects in the house.
I plan on removing the dirt around the house to bring the grade down to at least 6-8in below the top of the foundation wall. This of course will make my sloping problem even worse, but I was thinking I could install a french drain about 10 ft away from the house and have the yard slope down towards the drain from the foundation. This is all well and good, except that my septic tank is only about 8ft from the house, and the field runs parallel to the house from the septic tank. It seems that the top of my septic tank is only about 6in below the top of my foundation.
So I have a few questions.
1. How far from the house does my french drain need to be to really keep water away from the foundation?
2. How careful do I need to be about digging next to my septic tank/field? Can my french drain run right next to the tank(a couple feet from the field)?
3. Can the top of my septic tank be exposed to open air? Perhaps with a deck built over it with a hatch for access when I need to pump out the tank?
Any and all input is much appreciated.
Thanks,
Jonathan
Replies
Add on question:
Talked to a septic inspector, he reminded me I also need to be worried about keeping my sewage drain from the house insulated so it doesn't freeze in the winter... but that sewage line comes out of the house basically at the top of my foundation... So for that pipe to be above ground, to help with my grading problem, I need to insulate the sewage line somehow. Any ideas for insulating that sewer line?
We had a new tank put in about 3 years ago. I didn’t want the guys to have to dig around to find the lids so they are a little above grade level. We bought one that anything can drive over. Drain fields both old and new are sloped away from septic tank. Stay away from the drain fields is what I was told. The deeper ones are ok but for ours, the end of the field is quite shallow. We hire a septic company to drain ours every 3-5 years. We don’t do that work ourselves. Do you actually pump your own tank? I don’t mean that rude. It’s just with the heavy hose they work with I’m just wondering.
Because their hoses can get really dirty, I wouldn’t want it on my deck. Make it easy access and perhaps move the proposed deck away from it. Call Environmental Health for a copy of where your drain field is exactly. It will be a good reference if they drew it correctly. You’ll also need it so you don’t build or plant anything but grass over the one or two proposed drain field sites. Our 50 year old house went through 3 drain fields due to the tree roots. Thus our expense for the fourth field.
I’d also look at your gutters and downspouts. Directing that water away with solid pvc schedule 40. You may need a catch basin under the downspouts and then the pipe.
We recently moved to another home and had the black drain line with the holes removed and replaced with pvc. Again tree roots, etc had clogged them making them worthless
If you have a grader, they may be able to create a swell and redirect water away from your home. I’m thinking up at the top of the property and along the sides but of course it’s dependent on your property. Just throwing out ideas.
Thanks for the input!
My phrasing was a bit imprecise, I don't pump my own tank, I just meant easy access for when it's time to have it pumped, so I don't have to dig it up myself. Was thinking the hatch would be at the edge of the deck, so the pump hoses wouldn't be on the deck, just next to it.
I had a septic inspection when I moved in a couple years ago which has a pretty detailed description of where the septic field is. It's about 24in deep at the end that I'd be working near. I'm confident enough in it's location to know I won't be digging it up or anything(or be messing with a potential alternate location), but wasn't sure if the additional drainage near it would impact the effectivity of the field.