Outdoor drainage and softener backwash questions

[Thinly9172]

I have a heated outbuilding/workshop where I am planning to install a water treatment system for my drilled well.

The slab on grade outbuilding has a floor drain, intended for water softener backwash. The floor drain empties 4' underground about 20' away from the building. There is no drain tile installed but the soil is rocky and well drained.

My concern is twofold:

1. There is no P-trap in the floor drain, and I am concerned about odour/critters entering the building. I am considering removing the floor drain grate and sealing the pipe to only drain an utility sink, adding a P-trap under the sink, and directing the softener backwash to the sink. Will an AAV be adequate for venting in this scenario or will I need a vent to the outdoors? With the AAV I assume there is no way for gas to exit.
2. The in-ground drainage point is only about 30-40 feet from the well. I am concerned about softener backwash contaminating my water supply over time. How likely is this? The drilled well is ~120' deep.

Am I better off just running a drain pipe through the wall emptying to the surface?

Thanks all.

 

[WorthFlorida]

Your assumptions correct for paragraph #1
20' away I assume it is a dry well and the drain pipe is below the frost line. No critters could get in and with gray water only, there should be no odors.

If you seal off the drain, you need to add a vent through the roof. An AAV only allows air in. A sealed off floor drain will cause cause positive pressure in the drain pipe and you'll get gurgling because that air will back up past the P-trap.

 

[Sponsor]

 

[Reach4]

On number 2, I think it takes a long time for water to travel to where your well takes in water. When you drain into a pit filled with gravel, and usually covered with lawn, that is called a dry well.

 

[Jeff H Young]

floor drain to a drywell in a garage , maybe it was for snowmelt off a car Im from warm weather so wouldnt know .
Ive never put floor drains in garage and would suspect oil , gasoline and such and adding a utility sink might have issue dumping over a water well. Especialy in places with a lot of plumbing code or restrictions