A "cracker" plant is essentially a processing facility that takes ethane from fracked gas and cracks the molecules into smaller molecules that can be turned into plastic and other materials. A significant percentage of the end product created at this facility if it is built would be single-use plastic, however.
Click on the below links to websites that explain more about the "cracker plant" process:
Ohio River Valley: Another Petrochemical Sacrifice Zone (what is being planned and how the fracking industry is using this plant as a bail-out)
Underground storage is a proposed piece of infrastructure that could supply the cracker plant with gas liquids. The Ohio Valley Environmental Coalition has made some educational videos on the proposed Appalachian Petrochemical Storage Hub projects. Here is one:
Here is a detailed overview of the petrochemical build-out of the Ohio River Valley, including extraction of natural gas liquids, to transport, to plastics manufacturing- complete with detailed maps outlining the scope of the proposed projects: