Long Ravine Pipe Replacement
Project Details
Open Shield Pipe Jacking
- 72″ steel casing
- 30″ DIP for raw water
- 215′ crossing of I-80
Geotechnical Conditions
- Embankment fill consisting of sand, gravel, and weathered rock pieces
Challenges
- I-80 built on 50′ of embankment fill over old road or railroad
- Steep terrain
- Constrained work sites
- Difficult access to east side of crossing
Project Overview
As the trenchless subconsultant to Brown and Caldwell, Bennett Trenchless provided full design assistance, permit assistance, and trenchless submittal and RFI review for a trenchless crossing to replace an existing raw water pipeline. The existing pipeline was predominantly riveted steel pipe and open-channel conveyance that was installed in the early 1900s. During preliminary design, Bennett Trenchless evaluated several potential crossing locations, including an alternative for a trenchless crossing of the nearby UPRR tracks.
The final selected crossing location presented several challenges. It did not cross the UPRR tracks, but in this location I-80 was built on approximately 50 feet of embankment fill over an old road or railroad. The embankment fill had a high potential for unknown materials to be present, which posed significant potential risk for most trenchless methods. Two alternative trenchless designs were presented to PCWA: an open-shield pipejacking crossing in the fill and a deep microtunnel crossing below the fill in the native rock. The open-shield pipejacking alternative was selected, in part due to the challenges associated with access to the east side of the crossing and therefore in constructing a deep shaft. The trenchless component of the project was successfully completed in 2017.
Project Details
Open Shield Pipe Jacking
- 72″ steel casing
- 30″ DIP for raw water
- 215′ crossing of I-80
Geotechnical Conditions
- Embankment fill consisting of sand, gravel, and weathered rock pieces
Challenges
- I-80 built on 50′ of embankment fill over old road or railroad
- Steep terrain
- Constrained work sites
- Difficult access to east side of crossing
Project Overview
As the trenchless subconsultant to Brown and Caldwell, Bennett Trenchless provided full design assistance, permit assistance, and trenchless submittal and RFI review for a trenchless crossing to replace an existing raw water pipeline. The existing pipeline was predominantly riveted steel pipe and open-channel conveyance that was installed in the early 1900s. During preliminary design, Bennett Trenchless evaluated several potential crossing locations, including an alternative for a trenchless crossing of the nearby UPRR tracks.
The final selected crossing location presented several challenges. It did not cross the UPRR tracks, but in this location I-80 was built on approximately 50 feet of embankment fill over an old road or railroad. The embankment fill had a high potential for unknown materials to be present, which posed significant potential risk for most trenchless methods. Two alternative trenchless designs were presented to PCWA: an open-shield pipejacking crossing in the fill and a deep microtunnel crossing below the fill in the native rock. The open-shield pipejacking alternative was selected, in part due to the challenges associated with access to the east side of the crossing and therefore in constructing a deep shaft. The trenchless component of the project was successfully completed in 2017.