There is an alternative position in our school with respect to substituting the earth with some other cleaning agent. However, because this position is not the strongest in the school (and also not the official line - so to speak), there are reservations in adopting it.
There is really no great difficulty in using washing machines with clothes contaminated by Heavy Impurities. All you have to do in order to prevent the impurity from contaminating other non-Mughallaza items is to simply NEUTRALISE the Mughallaza first before you put them into the machine. Think of it as treating the particular garment(s) in question in the same way as you would when you manually apply a special conditioner to those garment(s) requiring special attention.
This is no different (in fact it is better because purifying Mughallaza is a mark of ta'abbud but applying special conditioners to your favourite garments is not). So once the 'ayn is removed (by the kayfiyya above) then just throw it into the machine for automatic washing!
