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Septic System & Dead Grass

The grass over the leach field in the front of our house always has problems in dry / hot weather. The last few weeks have left it completely brown, it may be dormant, but it looks dead to me. I need to do something with it because I don't think its ever going to get better, even if it comes back this year, next year it will probably die again.
Just to head off the questions - the problem area is very specific, and matches almost perfectly with the leach field markers. My neighbor who was here when our house was built recently told me the builder put in a plastic sheet over the leech field before the 'top soil' and grass.

Does anyone know of any specific precautions I need to take when I dig up the grass and replace it? Or why the plastic sheet is there? Or if I can remove the plastic sheeting altogether?

Thanks ...

Re: Septic System & Dead Grass

The purpose of the sheet would be to prevent washing down of soil into the leach material. I just wonder how deep it is and what type it is, as I suspect the grass roots are getting to it and absorbing something. Dig a small hole in the area with a hand tool to find the depth, if too shallow determine if adding soil would mess with the yard drainage. Also, sift the soil you remove for bugs, grubs, and worms to determine if there may be a ground temperature difference that results in overpopulation eating the roots. A good test for grubs is to pull on the grass to see if there are roots.

Re: Septic System & Dead Grass

It sounds like the plastic is at a shallow depth and is not letting the grass roots get deep enough to survive through a dry spell. We have a similar situation with grass that was planted over an old walkway. During dry spells this will brown out quicker than the surrounding grass. A couple more inches of soil over the plastic may help. I would not remove the plastic.

Re: Septic System & Dead Grass

Thanks for the replies. Its not grubs, the problem area is very specific to the leach field, and is around 20 feet square with very straight sides (and the grass doesn't pull up). I has a soil test done last year to try to figure it out, but it came back the same results (pretty much everything was good) as the rest of the yard.
I dug a 6" deep test hole yesterday, below the root line, and didn't find anything unusual - no sheet (plastic or otherwise). It was a quite rocky though, more than usual - and it looked like gravel (1" - 2") rather than the usual rocks I find in the soil.
Would excessive drainage cause my problems?

Re: Septic System & Dead Grass

Excessive drainage could be the issue since water is not staying near the roots of the grass. To prove this theory you would only need to water that specific area to see if the grass comes back.

I think that would be worth doing before putting effort into other changes.

If that does help then you need to mix in some dirt with the gravel that will hold onto the water better. As stated before, they should have put the weed block type fabric down over the stone in the drain field to keep dirt from seeping into it and silting it up - so adding the dirt should not cause a problem..

Just some quick thoughts on how to fix it would involve renting a sod cutter to remove the dormant grass, then get a load of topsoil and rototill that into the gravel then replace the sod.

Re: Septic System & Dead Grass

I had the same problem last year. My septic service
advised against removing the plastic. I added 2-3 inches of topsoil.

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