A surveying error by a city-contracted design consultant will likely delay a sewer-main replacement project on Fallen Leaf Lane for three to four months.
Los Altos Public Works Director Jim Gustafson told the Town Crier the error was first discovered by Pacific Underground Construction Inc. (PUC), which determined that a 0.25-mile-long sewer pipe on Fallen Leaf Lane in South Los Altos was too close to an existing 24-inch water transmission line.
As a result, Gustafson said the $1.7 million project – slated for completion in January – may not resume until spring 2013.
Specifically, Gustafson noted that the lines were within a foot of each other – in apparent conflict with design drawings provided by the city’s design consultant – Harris & Associates. The company has since agreed to revise the construction documents at no cost to the city.
However, because of the short distance between the lines, the project required a different method of sewer pipe removal than originally anticipated. According to Gustafson, the project originally called for the sewer pipe’s removal and replacement with a method called bursting – sending vibrations into the ground and using a ramming device to break up and remove piping.
Moving the project forward using the bursting method, Gustafson said, could cause the water line to break.
“We could weaken it and then it wouldn’t be properly supported,” he said.
The project staff report noted that an open-cut trench method is now required to complete the project.
The surveying error by Harris & Associates led the city council to terminate its construction contract with PUC Nov. 13 after city staff and PUC were unable to “negotiate a bilateral change order within the approved project budget,” according to the staff report.
The council, which originally approved PUC’s bid for the South Sewer Main Replacement project in May, authorized a new advertisement for bids on the revised project.