I am planning a stand alone washing machine drain to a French drain buried in the back yard. My plan is to have a traditional 44" from the floor standpipe (2" diameter) which will have a 2" P-trap then go out the exterior wall and take a few 90 degree bends before terminating into 2 "Infiltrator" extra capacity drains buried in the backyard. The two Infiltrator sections have 62 gallon capacity each, so I think that should accommodate one washing machine, since I think the ground will drain some of the water away as the washing machine is running. I have two questions:
1) Do I need to be concerned about odor entering the house through the standpipe, since this will be in no way connected to the house sewer?
2) Should I install another P-trap with a short vent pipe outside along the exterior wall just in case the capacity of the Infiltrator drain is exceeded? My thinking is that the extra vent below the level of the standpipe will drain off excess drain water if the Infiltrator cannot handle the gray water, and the extra P-trap between the Infiltrator and the short vent outside will maintain the trap seal and avoid odors coming out of the short vent.
1) Do I need to be concerned about odor entering the house through the standpipe, since this will be in no way connected to the house sewer?
2) Should I install another P-trap with a short vent pipe outside along the exterior wall just in case the capacity of the Infiltrator drain is exceeded? My thinking is that the extra vent below the level of the standpipe will drain off excess drain water if the Infiltrator cannot handle the gray water, and the extra P-trap between the Infiltrator and the short vent outside will maintain the trap seal and avoid odors coming out of the short vent.