Interstate commerce in action at the former stone quarry at Coplay, now the home of "clean fill" from New York City and environs. The material in question is trucked in from about two hours away because it does not qualify as "clean fill" by the environmental rules of New York or New Jersey where it would have to go to a landfill permitted to handle more hazardous materials. The rules make such facilities very expensive so they have to charge high "tipping fees." As a "bewneficial use" in Pennsylvania - filling in old quarries like this one and worked out strip mines in the coal regions farther north and west, the costs of regulatory compliance are much less. The result is that "tipping fees" in Pennsylvania are low enough to offset the greater transportation expense. And, a few years from now, this real estate located a few minutes north of Allentown will be very valuable as a site for housing, offices or industry.