IF that is REALLY a vent, then the washer has to connect with a sanitary tee, while the other side MAY connect with a "Y", assuming it is independently vented.
in ontario 1-1/2" is fine for washer drain..depending on the distance to p-trap for washer you can stack vent with the vent you are tieing into as long as there is no discharge above and you connect to "vent" using a T
You are confusing a "minimum standard" with one that is adequate under ALL conditions. In the wall washer boxes ALL have a 2" drain outlet for a reason. The washer trap does NOT need an individual vent, IF that riser is truly a vent and not a drain from upper floor fixtures. Another thing we do not know is what the right hand pipe that "goes into the ground" does or is for.