How does one go about having the alley behind one's house closed off in Detroit? Have you ever done this before? I tried searching the city's website but had trouble finding anything relevant. Are there fees?

My brother's house has no yard and it's on a strangely shaped lot on a block where the alley is very short. A business on the north already built a cinder block wall along the alley wall. If he could take over the alley adjacent to his house, he would have a nice courtyard. [[And homeless people wouldn't poop behind his house anymore.)