Quality of soil is not an obstical in Permaculture because you grow your own. Any the most damaged site could be turned in a garden of Eden, which has been shown many times over by Will Allen, Sepp Holzer and Fukuoma-san.
In urban enviromnebt and miniature skale it is effective to grow soil using vermiculture and vegetable garden and kitchen scraps.
Acidic soils with low pH – grow plants that thrive on such soils like Blueberries or bring pH to close to neutral by adding compost, grasing chikens or adding bird manure, using hugelcultur technique. In case of alkaline soils plus use aminal manure, urine.
Worms neutralizing pH and help adding nutriens like Ca by excreting CaC (calcium carbonate). Comphrey plants are accumulators of Ca and help to raise pH, also ash. Aminal and green manure add organic minerals like manganese, phosphorus, potassium.
Wet soils are usually more acidic, arid- more alkaline (pH8-10) wich is caused by calcuim, magnesuim or alkaline salts accumulation.
In poor, compakted soils plant deep-rooted plants like chicory, lucerne, daikon raddish, potatoes, jerusalem artichok and other tubers will aerate the soil and add a lot of nutriens, plus you can harvest some for yourself. Pigs like tubers and you can run few pigs on the area to add manure and for further soil loosening.
Prevent erosion by covering bear soil with local fast-growing plants (weeds). If slopes more than 15 degrees steep, make terrases, which will also help with water management.
Shape the earth, making rased and lower levelsto aid water retention and drainage.