Aerospace, electronics, and other high-technology businesses expanded rapidly in California during the 1950s, bringing population growth and rapid economic progress. These businesses also brought a huge volume of toxic wastes and the problem of safely disposing of them. A modern-day reminder of those years is the Stringfellow Acid Pits located near the Riverside suburb of Glen Avon, 50 mi (80 km) east of Los Angeles.

The Acid Pits, also known as the Stringfellow Quarry Waste Pits, are located on a 20-acre (8-ha) site in Pyrite Canyon above Glen Avon. In the mid-1950s, a number of high-tech companies began to dump their hazardous wastes into the canyon. No special precautions were taken in the dumping process; as one observer noted, the companies got rid of their wastes just as cavemen did: "They dug a hole and dumped it in."

Over the next two decades, more than...