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First you have to establish as Dan says the needed grade level then where does the water have to go to get away from the building. It looks quite flat in general; it may well be there never was any real consideration for drainage w/ every lot being built sequentially up to put their runoff onto the boundary and the heck w/ the end result to elsewhere. Is that alleyway a city easement or purely private property might have a bearing on whose job it is to reestablish grade on it if it isn't just access to the rear of your building for your use alone but is trash pickup, etc., etc., etc., ...
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