Case Studies: Current Projects
TBM proceeds on water storage plan in San Diego, CA
- Machine Type: Main Beam TBM
- Diameter: 3.5 m (11.5 ft)
- Tunnel Type: Water Transfer
- Tunnel Length: 2.75 km (1.70 mi)
- Owner: San Diego County Water Authority
- Contractor: Traylor-Shea Joint Venture
- Location: San Diego, California, USA
Project Overview
The San Vicente Pipeline, 17.7 km (11 mi) in length, connects the San Vicente Reservoir in Lakeside, California to the San Diego County Water Authority Second Aqueduct. The pipeline is part of the Water Authority's Emergency Storage Project that will provide water to the city in the event of a drought or major earthquake.
Project owner San Diego County Water Authority awarded the construction contract to the Traylor-Shea joint venture. The contractor chose a 3.5 m (11.5 ft) diameter Robbins Main Beam TBM and back-up system for two sections of the tunnel, totaling about 2.75 km (1.70 mi) in length. These portions of the tunnel pass through granitic rock geology with an Unconfined Compressive Strength of 140-345 MPa (20-50 ksi).
The refurbished TBM features 17 inch (432 mm) cutters and can generate a thrust of 6,005 kN (1,350,000 lb). The machine also has a maximum torque of 1,056,546 N-m (779,268 lb-ft) at the cutterhead. The Robbins back-up system consists of 11 decks and muck is being removed via muck cars.
Boring began on June 21, 2006 after an onsite TBM assembly of only 30 working days. The machine will first excavate 1.2 – 1.8 km (0.7 – 1.0 mi) west of the San Vicente Portal. It will then be removed and re-launched at the West shaft and will bore 1.3 km (0.8 mi) east.
Updates of this project will be posted as boring continues.
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