The former GAF shingle factory steadily expanded on Erie, Pennsylvania’s bayfront. As it grew, workers dumped construction debris, asbestos, tar, shingle trimmings and other industrial waste into the water and erected new buildings on the fill. Now, to remediate and redevelop the 12.5-acre site, significant containment will be needed. Two-thirds of the site will most likely require the installation of a two-foot-thick cover layer.