That Sinking Feeling

Sinkhole that ate Seacliff still eats at its residents

The affluent Seacliff neighborhood seems to have everything -- spectacular views of the bay, tastefully manicured yards, lots of open space. But beneath the beauty, residents have been assaulted, first by reeking rivers of sewage that roared down residential streets like Noah's flood, and now by smelly bureaucratic legerdemain.

Nearly two years ago, television viewers around the world gaped at the spectacle of a $1.5 million Seacliff mansion breaking into bits as it tumbled into a massive sinkhole, created when a sewer collapsed.

A study commissioned by the city of San Francisco Department of Public Works suggests that mistakes by city-hired contractors and/or the city's engineering staff caused the collapse. But the city is refusing to compensate some Seacliff homeowners for losses that resulted from the sinkhole. Meanwhile, the firms that originally worked on the sewer are being paid millions of city dollars to repair it. And the National Park Service is making sure that the sinkhole site itself remains a largely unvegetated eyesore.

Seacliff's sinking feeling began when Howard Billman looked out a window of his house on El Camino del Mar in the wet, pre-dawn hours of Dec. 11, 1995, and saw a 30-foot geyser of sewage spouting from his yard. A sinkhole was eating his driveway. Throughout the Seacliff area, neighbors rushed into the streets as raw sewage erupted from toilets and drains, and manhole covers exploded into the air.

Suddenly, a brick sewer under Billman's yard burst. Tons of liquid filth devoured the sandy soil and toppled trees. Neighbor Robert Werby saw the Billman couple, backlit in a window, and yelled at them to get out. The Billmans escaped as their car was engulfed by the sinkhole.

Next door, Walter and Ramona Yee's garage tilted as the ground underneath it disappeared. Yee's 650-pound safe fell into the maw of the broken sewer -- sliding a quarter-mile and winding up on a beach. Shortly after dawn, the Billman house crumpled into a pit of sewage.

City workers failed to plug the flood until the following day. In the interim, millions of gallons of storm water and sewage poured into the sinkhole, chewing away at the foundation of the Yee residence. Todd Cockburn, chief engineer with the city's Department of Public Works, announced plans to knock the Yees' house down, but Walter Yee, an engineer by trade, hired a crane to stabilize his building. Yee wrapped a sling of steel girders around his house, saving it and two adjacent homes from destruction.

As the rains and sewage subsided, neighbors say, DPW trucks dumped rubble into the hole -- forever burying the Billman house and evidence of the disaster's origin. DPW staff called the incident an "earth movement caused by rainstorm."

Twenty-one months later, the neighbors are still enraged by the city's refusal to accept any responsibility for the sewage eruption that swallowed part of Seacliff.

"The cover-up began in the first few minutes, when they called it a 'sinkhole,' " Seacliff resident Mary McAfee says. "A sinkhole is a natural phenomena. This was caused by poor judgment on the part of DPW."

The city Public Works Department hired Failure Analysis Associates, a Menlo Park consulting firm, to study the Seacliff sewer-sinkhole disaster. Under their $600,000 contract, the consultants issued a carefully worded report reconstructing the calamity.

According to the report, the collapse of the sewer was the result of an "intense, but not extraordinary rain-caused storm flow" that backed up in a brick sewer beneath Seacliff, because Public Works had constricted the ultimate outflow of the sewer. The pressure caused by the constriction forced water through cracks in the sewer wall, eventually scouring out enough sand to create the sinkhole, the report said.

But if the sinkhole swallowed homes suddenly, it was not created overnight.
The first sign of the sinkhole appeared next to the Billman driveway 11 months before the night of disaster. In the spring of 1995, Seacliff resident Melanie Marks made repeated phone calls to DPW complaining about the sinkhole, and nearby buckling sidewalks. She wrote to DPW on Nov. 20, 1995, saying, "We are concerned that permanent and irreversible damage is being done to our homes."

According to members of the West Presidio Neighborhood Association, DPW staffers finally took a look at the sinkhole, but failed to make a connection to its cause: a cracked brick sewer wall beneath it.

The straw that broke the sewer's back, according to the Failure Analysis report, was DPW's temporary constriction of the sewer's outfall opening, which caused the storm waters of Dec. 11 to back up and pressurize the brick sewer, finally venting through fissures between the bricks and breaking the sewer to pieces. Water gushing from the demolished sewer expanded the sinkhole until it became a 70-foot-deep pit that swallowed almost everything in sight.

Some Seacliff residents place blame for the sinkhole on inadequate construction oversight by DPW engineers supervising the building of the Richmond Transport Tunnel, a two-mile-long bore running 40 feet under El Camino del Mar.

The tunnel was conceived as a large sewer connecting the Presidio to a sewage treatment plant at Ocean Beach. One tributary to the tunnel was the brick sewer that collapsed under Howard Billman's home. As part of the tunnel project, the brick sewer was to be lined with insulating pipe before nearby excavation work was performed. "Because the brick was never lined, sand leaked through a crack causing the soil overhead to collapse into a sinkhole, like sand through an hourglass," says neighborhood association member Joanne Lindeke.

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