For subscribers to the eastern Pennsylvania newspaper the Morning Call, the American underclass is no abstraction. At least not this week, thanks to Spencer Soper.

Soper is the guy who found a whole bunch of people working under trying conditions at’s Lehigh Valley warehouse facilities. One of them was employed as a “picker,” meaning he had to “scurry” around an enormous warehouse fetching items to be packaged and shipped away. Take it away, Soper:

He said he was expected to pick 1,200 items in a 10-hour shift, or one item every 30 seconds.

The warehouse is organized like a library. Bins labeled “A” were on the floor. Dim lighting in the warehouse in which he worked made it difficult for him to find items stored in the low bins, especially novels with script titles or CDs with small writing, he said. Often, he got on his hands and knees to find things in the low bin, and would crawl to other bins rather than continuously stoop and stand, he said.

“The worst part was getting on my hands and knees 250 to 300 times a day,” he said.

Such tales of hardship at the Amazon facility, writes Soper, are by no means “unique.” Over the course of two months, he collected the accounts of 20 current and former warehouse workers, and their accounts buttress one another.

The theme: Workers bang away at the reciprocal task of filling the warehouse and emptying it out, all while being carefully monitored for productivity. If they don’t “make rate,” they get written up, written up again, and perhaps terminated. All that hustling often goes down, Soper explains, in conditions of extreme heat. Here’s this:

Heat prompted complaints about working conditions at Amazon to federal regulators who monitor workplace safety. The Morning Call obtained documents regarding the Occupational Safety and Health Administration’s inspection through the Freedom of Information Act.

On June 2, a warehouse employee contacted OSHA to report the heat index hit 102 degrees in the warehouse and 15 workers collapsed. The employee also complained that workers who had to go home due to heat symptoms received disciplinary points.

“The 102-degree heat index only applied to the first floor and not in regards to the second or third floor … I just believe that it is gross negligence for a company of this capacity to abuse and enslave their workers,” the complaint states.

There’s a good lesson for newspapers in Soper’s detailed and compelling investigation: If there’s a name brand employing lots of people in your coverage area — Amazon certainly qualifies — take a look at how it treats its employees.

Soper came up with his scoop in a more traditional, stumble-upon fashion. The paper had gotten a tip that some workers were being told they had jobs at the Amazon facility, yet when they showed up, no work. After doing that story, the paper got some tips from people who had worked there — they weren’t happy stories.

Those initial tips, Soper said in an interview, triggered some recollections for him. He had been working the jobless beat and recalled how a couple of people here and there had told him about the Amazon situation. “In the spring, I was interviewing people looking for work, and several mentioned that they worked at the warehouse. They said, ‘I tried that and wasn’t cut out for that,’ ” Soper said. Such mentions, he added, were vague and stated offhandedly, and so they didn’t place any blips on his journo-radar. Yet when joined with what he’d learned elsewhere, they meant something.

Time for immersion. Soper spent nearly two months networking his way to a story. In addition to interviewing workers, he got records from OSHA and tracked down emergency workers and the like. Along the way, he did his “On the Cheap”column — recent entries include “Stop wasting milk and juice” and “Never buy oil for your chain saw again.” — as well as some spot news stories and his five-times-per-week biz newsletter. That’s the price of enterprise at a paper with just over 40 reporters.

Impact? Soper said he’s received “multiple” e-mails from people who say they’ve either stopped doing business with Amazon or have complained to the retailer and are awaiting a response before making a decision. He hasn’t heard from Amazon.

He has heard from the Internet, though: The Amazon warehouse package got nine times the traffic of a typical Morning Call story.

NOTE: Item was changed to reflect a new reporter count from the Morning Call. It originally said it had 29 reporters.