Question
This is similar to a previous question. I have just noticed that the grass over my septic tank is dead, forming a perfect brown silhouette of the tank in the middle of my otherwise green lawn.

The lawn is well established and is now seven years old. I have not seen this problem before. The tank is about 6-8 inches below the surface, which seems like enough, but maybe not? We recently had a lmost a full week of heavy rains here in southern NH, could this be standing water killing the roots and a "one time" event?

Could this be a heat issue above the tank? Why haven't I seen this before?

I cannot add additional topsoil, since the entire lawn and drainage field is at the same elevation and pancake flat, meaning that type of fix would involve my entire lawn (75 x 75). Any ideas?

Answer
hi Jeff;
You could use a little more soil over that area. 6 inches is pretty shallow.
Could be, because of the extra rain, you have brown patch fungus.
Horticultural corn meal made into juice and poured over it will kill fungus.
1 cup horticultural corm meal per 5 gallons of water, let set 30 minutes or more and pour pour over the area.
Yopu might consider putting a little wall around that area, and make a raised bed for flowers, strawberries etc, or make an outdoor patio and lay bricks, paver stones etc on it so it would be easy to remove should you need to for maintenance of the septic tank/
I don't know if that would be too much weight above the tamk. Don't know a lot about septic tanks.
If grass has been doing well there up to now, I would trewat the fungus, and sod in some more grass or plant some, or if it is a fast spreading grass, let it fill in.
Charlotte