Can you put a Paver patio on top of a vertical leach field

[njsdesigns]

The house is 1 block from Lake Michigan the soil is 100% sand The property has a tank and 3 dry wells for vertical leaching. The ground space is about 500 square feet currently with grass. As a landscape designer, the client is asking for a patio in this space. Is the rain water a requirement for the leach system to operate or is the normal flow of gray water enough for it to perk out properly. The flatwork material would be pavers, therefore removable in an event of system failure. If it needed to be the project could use permeable pavers to let in a larger % of rainwater. Appreciate the help in answering this project question

Ned Swanson

[Stuart Meade]

Ned,

 The problem isn't lack of rainfall, it's lack of oxygen.  A grass cover (over a septic system) allows the systems to "breath" by injecting oxygen into the system through the root system AND it's roots keep the soil pore spaces open and keep it from getting compacted (which can restrict the exchange of air and water).

I have seen above ground pools quickly kill a functioning septic absorption system.  Perhaps these systems were already on  their way to failure but the addition of the pool over the top seems to quicken the process.

Remember that a large percentage of the soil is pore space. 
By putting pavers over your septic system, you are blocking the majority of these pores at the surface and slowly compromising your system's ability to breath.

Grass cover is what's recommended.  If you "need" to install a patio, pavers, with lots of holes in them, are your best choice.

[jmenchhofer]

To avoid impacting the pore spaces even more, a wood deck installed up off the ground may be another suitable alternative.  The feasibility of this idea would depend on whether there is enough fall from the door of the home to the ground where you are wanting to put the patio.  Also, you would have to arrange your deck supports in a way that would avoid placing them in the leaching areas.

[Stuart Meade]

To avoid impacting the pore spaces even more, a wood deck installed up off the ground may be another suitable alternative.  The feasibility of this idea would depend on whether there is enough fall from the door of the home to the ground where you are wanting to put the patio.  Also, you would have to arrange your deck supports in a way that would avoid placing them in the leaching areas.

That's good advice.

Yes, keep the supports away from the field.  I've seen wooden supports wick-up sewage up from below.  It give the wood a very distinctive look!

[Toxic Avenger]

First thing you should have done, if you haven't yet, is contact the local health department for the county you are working in.  Every county has their own specific requirements when constructing ANYTHING over a septic system.  Some allow it with the submittal of a variance request or affidavit signed by the homeowner.  Others don't care at all.  And some don't allow decks, sidewalks, pools, etc. to be built over a septic system period!