One thing.... Tanneries invariably produce huge amounts of toxic waste in the form of acidic washes of ash or urine, pollutants such as fecal matter used to produce soft buckskins, and rancid fats. Pretty much anything nasty that is a byproduct of other things is a valued agent used in tanning skins. That means that a) tanneries are always on a river so that their waste will be carried away; b) tanneries are always DOWN river; c) tanners are not terribly popular at highschool pep rallies; and d) tanneries tend to be well away from the rest of the village and always down the prevailing winds.

Just something to consider.