Culvert repair contract authorized to go to bid

The San Diego County Board of Supervisors authorized the advertisement for bid and subsequent award of a construction contract which will repair nearly two dozen culverts in unincorporated San Diego County, including three in Fallbrook.

The supervisors' 5-0 vote April 8 will reline 70 feet of culvert along Winter Haven Road 1,250 feet east of Clear Crest Lane, 55 feet of culvert along Gird Road 1,085 feet north of Sicomoros Lane, and 40 feet of culvert along Reche Road 530 feet east of Gird Road. The contract is structured to include a base bid with 10 locations along with additive alternatives, or clusters of locations which can be added to the contract should funding permit, totaling an additional 13 locations. All three Fallbrook locations are part of the base bid.

"Countywide we depend on over 14,000 drainage culverts to keep water off our roads during rain events. Public Works staff identified three culverts in Fallbrook that need repairing," said Supervisor Bill Horn.

The more than 14,000 culverts are among more than 18,000 drainage facilities maintained by the county's Department of Public Works in the county's unincorporated area. Stormwater crews inspect all county-maintained culverts on a cyclical basis and prioritize them for rehabilitation or replacement. Field engineering staff members inspect the culverts nearing the end of their service life to determine whether the more preferable option would be replacing the culverts or rehabilitating them with new lining.

Lining a culvert involves the installation of an internal sleeve. Lining methods include cure-in-place pipe which utilizes resin-impregnated fabric inserted into the existing culvert, slip lining insertion of solid wall surface into the existing culvert, and insertion of spiral-wound pipe which will expand and line the culvert. The internal sleeve restores the pipe's structural integrity while reducing excavation and thus minimizing traffic impacts.

Repair of holes and the restoration of capacity without replacing the culvert can also be accomplished by invert paving which consists of preparing the invert surface area, or the bottom of the culvert, to receive concrete, installing bar reinforcement and anchorage devices, and paving the inverted area with concrete on the bottom of the pipe to fill existing holes and restore it to a structurally-sound pipe floor. If the culvert is damaged beyond economical repair, a culvert replacement is more appropriate than rehabilitation and the existing culvert is removed with a new one being installed.

The estimated cost of the contract, including contingency, is $450,000. Highway User Tax Account revenue derived from the sales tax on gasoline will be used.

All of the culverts are within county right-of-way or in locations where temporary access has been granted. The work is scheduled to begin in summer 2015 and be completed in late 2015. Traffic control measures will be implemented to minimize the impact to travelers. "The repairs should start this summer and be completed in time for any winter rainstorm," Horn said.