The Asbestos Release Site (the Site) is an approximately 112-acre area located in the center of Valley Forge National Historical Park (VFNHP) in Montgomery County, Pennsylvania.
In the early 1800s, portions of what is now VFNHP were quarried for limestone. From the early 1890s to 1970s, the Ehret Magnesia Company and its successor, the Keene Corporation, manufactured asbestos insulation products at a plant located on private land within what is now the park. The products were manufactured by combining imported asbestos fibers with magnesium carbonate from the dolostone present within the local limestone deposits. The manufacturer disposed of asbestos slurry waste by pumping it through pipelines into the former quarries or by directing it to a waste channel constructed in a natural drainage swale that runs to the Schuylkill River. The slurry waste placed in the limestone quarries was subsequently covered with soil and in some locations, asphalt.
The National Park Service (NPS) discovered the asbestos contamination in 1997 during the excavation of a trench for a fiber optic cable.