Seventy first-year graduate students in the Tepper School of Business at Carnegie Mellon University got as dirty as coal miners yesterday gutting four, century-old houses. Another 170 got rained on hauling pallets, pushing wheelbarrows, lugging mulch and collecting litter.

It was the street-level component of a day rooted in ethics -- day one of Orientation Week at CMU. After a two-hour lecture on ethics and decision-making, 220 first-year students in CMU's master's of business administration program and 20 in their second year fanned out to engage in good works.

"Business relies on the community for its success," said Dr. John Hooker, who conducted the morning lecture. "If the community doesn't survive, business doesn't survive.

"An experience like this sensitizes students to the fact that they are part of the community."

The ethics-in-action project was Darren Sabom's brainchild. The 31-year-old native of McCandless, a second-year student, planned the logistics for 13 large jobs that included partnerships with two businesses, three nonprofits and a high school.

Mr. Sabom studied biology at Occidental College in Los Angeles and joined the Peace Corps in 1999. He was assigned to Micronesia for his two-year stint. When he came back, he got jobs in construction and developed an interest in real estate.

"I went to business school so I could understand the finances to make large-scale development projects work," he said.

In CMU's student government, he is the community outreach coordinator. Yesterday, he drove a pick-up truck from site to site coordinating the arrival of students and distribution of supplies.

His daylong venture, "BOOST! Cultivating Community in East Liberty," came complete with green "BOOST!" T-shirts. East Liberty benefitted, in part, because of a connection with a recent CMU grad who works for East Liberty Development Inc.

For each of the 13 jobs, Mr. Sabom secured a site manager.

Friends of the Pittsburgh Urban Forest managed weeding, planting and mulching at two gardens on Penn Circle. East Liberty Development managed four sites. Mosites Construction Co. managed the cleanup on Highland Avenue. And a board of education employee oversaw the work of 10 students who removed Belgian blocks from around 10 trees at Peabody High School and mulched them.

Three of the sites were vacant lots that GTECH, a nonprofit of CMU graduates, had targeted for soil remediation. Twenty students at each site cleaned the lots and prepared them for bio-fuel crops.

In the 5800 block of Rippey Street, a bus unloaded 70 students wearing their "BOOST!" T-shirts and heavy shoes to gut two turreted three-story duplexes. The buildings spent decades as rooming houses and were in various stages of collapse when East Liberty Development bought them in 2005 and 2006.

With dust masks, hard hats, crow bars, mallets and five-gallon garbage cans, the students split into four groups, two per duplex. A half-dozen particularly muscular students were designated to haul refrigerators, stoves and cabinets. All metal was saved for recycling.

From the front porch of 5809-5811, East Liberty Development's Kendall Pelling told the students, "You'll save us $50,000 and reduce our need for grant money" in rehabilitating the properties for the market. "Thank you for coming."

"Thank you," several of them chorused, cheerful at the notion that they would be spending the next five hours hammering plaster, tearing lath and flooring, removing doors and hauling waste to dumpsters.

Swetha Bharadvaj lit up at the idea. "This will be great," she said. "It's a great project for us. We were talking earlier about ethics and the importance of acting with a broader perspective" beyond business.

"This sounded fun to me," said Sereana Seim. "They told us we'd get filthy. I said, 'Sign me up.'"