Slag is a by-product of the steel making industry. For each ton of steel a ton to a ton and a half of slag was produced. Slag is an inefficient soil medium for establishing plants. Its steep slopes, porosity and typically high pH create a challenging environment for plants to establish themselves.
In light of this, Pittsburgh City Planning approached the Environmental Protection Agency with a proposal to develop a multi-tiered experiment to understand the potential for revegetating steep slag slopes without incurring the costs and disruption to the tenuous ecosystem of additional grading. The upper slopes, graded by the developers for the housing development, will receive an expensive but well thought out soil and vegetation planting. A research team led by soils scientist John Buck of Civil and Environmental Consultants, with botanist Sue Thompson of the Carnegie Museum of Natural History and members of the STUDIO, developed a greenhouse study and on-site test plot program. The intent of the study was to outline a program of successful low maintenance revegetation, which targets soil remediation and a vegetation mix which provides maximum habitat value and aesthetic opportunity through the use of native plants.
Some of the plant specimens discovered onsite by Sue Thompson were pressed and displayed on the wall. On the table were two examples from the actual greenhouse study, cared for and managed by Reiko Goto. The accompanying video by Bob Bingham illustrates the conditions and changes that are occurring on the slag slopes today as nature struggles for a foothold and the development proceeds with its site preparation.
This year's growth has been constrained by the recent drought, but as a long term sustainable ecological restoration, the plants are selected for their ability to weather such conditions. Seeds which have not germinated this year will continue to be viable next year.