Equipment Type

Waterfront Upgrade In San Diego

Working conditions at the Tuna Boat Basin Seawall and Revetment Repairs site in San Diego do not get any better than this. With the USS Midway docked nearby, perfect weather, boats of all types cruising the blue harbor, seagulls flying, and curious tourists watching intently, Southern California trumps Minnesota construction in winter months.

March 02, 2009

Working conditions at the Tuna Boat Basin Seawall and Revetment Repairs site in San Diego do not get any better than this. With the USS Midway docked nearby, perfect weather, boats of all types cruising the blue harbor, seagulls flying, and curious tourists watching intently, Southern California trumps Minnesota construction in winter months. RCC General Engineering Contractors was the successful bidder on this nearly $1-million job.

Project

Original sea wall was built in 1920s or 1930s and had developed safety hazards. (Photo: Webb Wiley)

The wall and walkway that passes in front of a restaurant had some safety issues.

"The existing revetment was constructed in the 1920s or 1930s with rock and broken concrete sidewalk — stacked with a concrete surfacing," says Webb Wiley, RCC's spokesman. "Over the decades it was undermined, and in some locations it had actually failed."

Demolition and Surprises

Repairs called for removing existing soils, rock and concrete and replacing it with a section consisting of fabric and filter blanket of 3-inch rock with a protection layer of 1/4-ton riprap. In some areas the plans called for pressure grouting to fill voids under the existing sea wall and concrete sidewalk.

"During the course of construction we discovered the voids were more extensive than shown on the plans," Wiley said. "Some of the voids under the sidewalk and sea wall were large enough that a person could sit in them. Because of this we removed the entire sidewalk and in some places removed and replaced the sea wall."

Special Construction Techniques

Wiley added, "We had to excavate a toe trench to place rock under water. Because of the fluctuating tide — to assure we excavated this trench accurately — we used a laser and divers in the water to check grade during this operation and while placing the rock protection section. We also had to use a turbidity barrier to assure water quality in the bay met EPA requirements. A work boat was used to help in both functions."

Construction Sequence

  1. Removal of the existing revement
  2. Bracing and shoring of the existing sea wall
  3. Compaction of the existing soils, and in some places replacement of the existing soils with imported base material
  4. Reconstruction of the rock slope protection section (up to 10 tons)
  5. Pressure grouting voids
  6. Removal of the sidewalk where it failed
  7. Filling the larger voids with concrete slurry and base material
  8. Reconstruction of the existing sea wall
  9. Replacement of the sidewalks

Volvo 460 excavator with thumb attachment for removal and replacement of the existing sea wall and slope protection.

Heavy Equipment Use

  • Volvo 460 excavator with thumb attachment for removal and replacement of the existing sea wall and slope protection
  • Volvo 110 wheel loader to assist in the removal and replacement and general duties throughout the project
  • Cat 248 skid steer to assist in placing the rock
  • Bobcat 331 excavator with a breaker attachment to remove sidewalk and to selectively remove portions of the sea wall
  • Cat 320CL excavator to assist in removals and replacement of the rock
  • Specially built bucket for the Volvo 460 excavator to reach beyond the bottom of the existing slope underwater to excavate a toe ditch and to place rock in this area

Construction Niche

"We've been rebuilding things for over 30 years," says Wiley of the Montrose, CA-based company. "We like to undertake the more difficult projects, specifically the projects that require some type of reconstruction slope repairs, failed foundations, etc. We just recently completed a $6.2-million slope repair in Malibu."

Work on the San Diego project began in September 2008, and should be completed by March 2009.

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