Three days later, the neighborhood was back in turmoil after a large water main broke, flooding homes, cars and a school campus -- including the gym where the party was held.
The 42-inch pipe ruptured around 11:10 a.m. Tuesday on Sunnydale Avenue between Cora Street and Tomaso Court, prompting the evacuation of 14 homes and the nearby Our Lady of the Visitacion School. The break left a gaping hole several feet deep in the street.
Joseph Moreno, 42, was one of a number of residents who were initially displaced but were allowed to return home Wednesday.
Moreno, who has lived in the neighborhood for about 30 years, said that while some of his neighbors had flood damage, his family's house was intact. However, he said, the water got into his son's car, which was parked in the driveway.
He said that although he and his family have been able to move back in, his home still does not have hot water.
"I took the coldest shower ever in my house this morning," Moreno said. "It's been rough."
He said neighbors have been wondering whether the rupture of the water main was connected to the sewer project, which had caused Sunnydale Avenue to be reduced to one-way traffic for at least a year.
"It's a coincidence that they just finished the road," he said.
Last weekend's celebration to mark the end of the project was held at the Our Lady of the Visitacion Valley school gym. Church secretary Betty Campos said about 40 or 50 people attended.
San Francisco Public Utilities Commission spokesman Tyrone Jue said the completion of the sewer project and the main break are not connected.
"They're completely unrelated, not even in the same vicinity," Jue said. "Where the pipe broke was a new installation done about a year ago."
He said the cause of the rupture remains under investigation, and that officials are looking to see whether the pipe was defective or whether it was incorrectly installed.
Jue said it could take as long as three weeks to bring in a replacement pipe and repair the roadway.
The full cost of the water main break has yet to be determined because "reimbursement costs will trickle in over time," he said, adding that residents have a year to file a claim with the city attorney's office. They can do so by calling (415) 554-3900.
Moreno said his family has yet to file their claim, which he said will include time taken out of work to look after his family, including a grandmother with a broken leg.
Meanwhile, classes have been canceled at the Our Lady of the Visitacion K-8 school until next Tuesday while crews clean up the flood damage to classrooms, the gym and administrative offices.
Campos said the church was not damaged by the water, and services will continue as usual this Sunday.
Anyone with questions about the incident is asked to call the SFPUC at (415) 554-3289 or 311. Information will also be posted online at www.sfwater.org.