Bernard F. Brown

The helicopter was worth a shot, Dave Fahnestock thought. The owner of Hands on the Earth Orchard in Lititz, Lancaster County, which sells apples and peaches at farmers markets in Clark Park, Rittenhouse Square and Bala Cynwyd, hoped the downdraft from the propellers would mix warmer air with the freezing air hugging the ground across his 15 acres of fruit trees. In the days leading up to April 20, he had watched the forecast for the overnight low temperature go from worrisome to disastrous.

The past three summers in Philadelphia have seen smoke drifting overhead, making for beautiful sunsets and, when it settles close to the ground, hazardous air. That smoke came from forest fires that burned thousands of miles away in the boreal forests of Canada. These woods cover 270 million hectares (or about one million square miles) in Canada, equivalent to about 29% of the United States’ land area.

Every human produces a little more than 4.5 ounces of excrement per day. Multiplied by the 2.2 million customers of the Philadelphia Water Department’s wastewater system, the cumulative daily dump equals about 620,811 pounds, or about 310 tons. The story of biosolids (treated sewage sludge) starts with clean water in the toilet bowls of the residents of Philadelphia and surrounding suburbs.