There's a reason why "down in the dumps" means what it does, and you could visit any of 279 known sites in the city to feel that way. We'll start with Duck Hollow, between the Monongahela River and a railroad line, where it appears contractors have tipped to avoid landfill tipping fees.

At least three dump trucks could fill up on the trash that has accumulated there since Joe Divack and Derek Green helped clear it last fall. Along the tracks and down the hillside, debris sits in piles and hangs enmeshed in invasive overgrowth: tires, roofing material, siding, windows, cabinets, landscaping debris, a TV frame and motherboard, bulging black bags and old carpet so embedded it looks like orange fungus that grows in rectangular strips.

"People in our region can exhibit shockingly bad behavior," said Mr. Divack, a retired behavioral therapist who received a "Bob Award" as Volunteer of the Year last week from the Clean Pittsburgh Commission. "We foul our own nest."

Boris Weinstein, founder of Citizens Against Litter and a Clean Pittsburgh Commission member, introduced Mr. Divack to Mr. Green last fall. The two men have, with one or two other volunteers, cleaned up 15 illegal dump sites since then. Mr. Green said 279 "sounds daunting, but if we can get 40 or 50 volunteers, we should be able clean 150 this year."

The campaign to clear the city of illegal dumps is the sole project of Mr. Green's nonprofit, stashthetrash.org. He bought the domain name last fall and has used social networking sites like Facebook to gather volunteers. He hopes that some contractors will join the fight.

His plan is to find stewards for each cleaned site "to maintain it and call us if they need help."

The effort will focus in Greenfield this spring. Greenfield has 20 known dump sites, more than any other neighborhood.

One day last week, Mr. Green and Mr. Divack toured the sites with a reporter.

"There's my pile," said Mr. Divack as he drove through a gravel lot toward an office chair, a shopping cart, a bunch of tires, stacks of lumber and bags and bags of trash. The pile sat behind homes along Calvary Cemetery in Greenfield. "We're hoping public works will pick this up soon," he said.

Mr. Divack, who retired last year, said he had "never done anything about the Pittsburgh environment except complain." He came to Pittsburgh in 1962. He had his "Eureka!" moment last year.

"My wife and I have relatives buried in a cemetery in Sheraden. It is surrounded by woods, and for years, I've noticed the trash outside the chain link fence. I just decided one day to clean it up. When you're paying your respects to loved ones, you shouldn't be seeing broken toilets."

He spent several weeks clearing away drywall, spackle buckets, rotten logs, concrete blocks, tires and large household rejects. "It's very, very hard work rolling a water heater uphill, and buckets filled with concrete are heavy. When I stepped back and looked, it looked so much better I determined I would keep doing it.

"I discovered I really liked doing this."

After joining a community cleanup around the Sheraden skateboard park, he said, he saw a letter from Mr. Weinstein in the Pittsburgh Post-Gazette. "I called him looking for more work."

At the same time, Mr. Green was looking for help cleaning dump sites.

"I buy foreclosed houses and fix them up," he said. "There are dump sites around a lot of the properties my company works on. We have to clean them up to get the houses on the market. I realized when neighbors came out to help me that it actually made me feel good."

Now he has a nonprofit through which to do the work "and access to a pickup -- mine. We need bigger equipment," he said, including a chipper for invasive plants.

Mr. Divack said invasive growth is "a huge problem," and not just for native plants. Along a guide rail on Flemington Street in Greenfield, he pointed down a hillside that he, Mr. Green and other volunteers cleared of six tons of dumped debris, "but it still looks awful," he said. Woody vines entangle damaged, split and fallen trees like netting. "It almost looks like an appropriate place for a landscaper to dump."

The next big event is to clean along upper Browns Hill Road.

"I'm excited about tackling that," said Mr. Divack.

"Yeah, it's disgusting, and it's right there in your face," said Mr. Green.

By contrast, Duck Hollow is secluded, a no-man's land that could be an extension of the Three Rivers Heritage Trail all the way to Braddock, said Mr. Green. Instead, its seclusion and trashy vegetation invite people to abuse it, said Mr. Divack.

"There's still that old mentality where people think it's OK" to dump on someone else's land, he said. It's apart from where they live, usually over a hillside. "Out of sight, out of mind.

"People come out to yell at us when we bring stuff up [from a dump site.] They thinking we're dumping. People have no idea what's on their hillsides."

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