Question
Zone 6 - Western NY.  I have a big problem growing grass over the septic tank (most likely due to escaping gases).  The area is a southern exposure and gets a lot of sun in the summer months.  When the septic system was installed many years ago, the contractor hit shale (hard digging), so the septic tank was not placed as low into the ground as it should have been and as a result the area is somewhat mounded higher than the rest of the yard.  Each year, we try putting more topsoil (there is probably about 3" topsoil above the tank), but don't want to keep building it up because it is already higher than the rest of the yard and looks somewhat strange.  To make matters worse, the area is directly to the left of the side entrance door and in direct walking line to the backyard pool and patio, so it gets heavy foot traffic.  Other than bringing in tons of topsoil and gradually feathering the entire yard surface to meet the highest point over the tank, is there anything we can do to keep grass on this area.  I've thought of stone landscaping or pavers, but every 3-5 years, the septic tank cover must be dug up and removed for pumping out, so that's not really a viable option.  Thanks.

Answer
I don't believe it is escaping gasses, but rather shallow soils - 3-4" just isn't enough to keep grass alive.  Plus, if you have a concrete tank, it contains lime, petroleum sealers, and sometimes root inhibitors (the plastic tanks sometimes have this) and other chemicals that are not conducive to good turf - imagine spreading 4 inches of dirt on your driveway, then trying to grow grass on it...especially if it gets heated up by the sun-exposure!

You may be able to keep it alive longer if you use pre-grown turf sod, that you see in the larger supply stores, in rolls or squares.

I installed a paver patio over a septic tank, and had "duckboards", or square doors put ontop of the inspection and access manholes (it had two openings).  When they service the tank, they only need to get at these holes, not dig the thing up, afterall.  You can place a large, removalble pot or planter box over the lid, and still provide access every few years, or so.  As long as you don't cover over the septic field with hardscape, I think you'll be able to do what you want over the TANK portion of the system, and not cause problems.

~Marc