The DEC report from 2006 states "Flintkote began operations as a manufacturer of felt and felt products in 1928, when the property was purchased from the Beckman Dawson Roofing Company. In 1935, Flintkote began production of sound-deadening and tufting felt for installation and use in automobiles. Manufacturing of this product line was continued at Flintkote until December, 1971, when operations ceased and the plant closed. It is also believed that Flintkote manufactured composite laminates similar to those produced at the Former Spaulding Composites Company in Tonawanda, New York. Such material was observed in the southernmost demolished building on the 300 Mill Street Property.
The disposal history of the site is largely unknown, although aerial photographs suggest that disposal of fill on the island was taking place by 1938. The nature of the fill material at that time is unknown. It has also been reported that ash resulting from the burning of municipal garbage was dumped at the site. The fill material on the 198 Parcel and Island is consistent with such a source" (good stuff here http://www.dec.ny.gov/docs/regions_pdf/flintrod.pdf)
The county plans to remediate and develop the area into a park. The US EPA has pledged $300,000 for clean up of the site. The DEC report shows they chose to commence "Excavation and Containment" of the waste at the site, which included demolition of all buildings, with a cost of $5,552,000.
Demolition began in 2014