Impact of Mining and Development
Prior to 1930, extensive room and pillar underground coal mining took place in Hays Woods. Pittsburgh Development Group (PDG) II plans to remove all remaining coal using Mountain Top Removal strip mining before construction begins.
In PDG's plan, the site's forests, containing mature stands of oak, poplar, maple, cherry, walnut and other trees will be logged, resulting in loss of habitat and displacement of resident wildlife. As this island of forest in the urban landscape is destroyed, large numbers of wildlife will flee to adjacent neighborhoods.
example of a logging operation
After the forest is logged, overlaying rock strata will be blasted away to expose the coal seam. This blasting will occur within 1/2 mile of surrounding homes. The airborne particulates produced by blasting may create a serious health hazard, which will affect the communities of Baldwin, Hazelwood and Hays.
More than 13 million cubic yards of earth will be moved. The hills will be excavated to depths up to 200 feet and the excavated overburden will be used to fill in the stream valleys to produce a flat landscape for development. These valley fills will bury 3 wetlands and 6 streams. These watersheds, and their forests, mitigate storm run off into adjacent watersheds, which are prone to flooding.
This mining activity will reduce the overall elevation of the site by 90 feet. As much as 1,200,00 tons of coal could be removed from Hays 
Woods over an 18-month period, requiring some 60,000 truck trips along Glass Run Road and Carson Street to the Hot Metal Bridge and Parkway. Because of recent major commercial developments in the neighboring communities of Homestead and South Side, these routes are already overburdened with traffic. To date, PDF II has not submitted a traffic analysis to the City of Pittsburgh.
It is unprecedented that Mountain Top Removal methods of coal mining will be used in an urban setting.