Venice Dual Force Main
Summary
The Venice Dual Force Main (VDFM) project involves the construction of a new 54-inch-diameter (1,375 mm) force main sewer extending approximately 10,400 linear feet (3,170 m), which originates from a newly constructed manifold adjacent to the Venice Pumping Plant. The majority of the new 54-inch line will be constructed using the microtunneling method. Cut-and-cover will be used for the final 900 feet (274 m) from Vista Del Mar to the CIS/NOS junction structure.
- 10,400 linear feet (3,170 m) of 54-inch-diameter (1,375 mm) force main sewer
- Microtunneling
- Permitted for 11 launching and receiving pits
- 50-foot-deep (15.2 m) watertight shafts
Scope of Work
Delve Underground was selected to provide construction management services to the City on the project, which included engineering support during construction, inspection services regarding the tunneling operations, construction management of various tasks, and claims mitigation services. For example, Delve Underground was tasked to review and comment on the contractor’s cost proposals submitted to the City for redesigns and extra work claims.
Challenges & Innovations
The contractor proposed a no-cost change order to delete the two microtunnel access and receiving shafts along the alignment. The contract contained a value engineering clause that allowed shared cost savings for deleted work. The City and the contractor negotiated the final pricing and issued a deductive change for about $340,000 in cost savings.
The project is being constructed in an environmentally sensitive area and required numerous permits from various agencies to monitor aspects of the project. Delve Underground assisted the City in determining the payment structure and whether additional funding may be required to comply with the required monitoring.
The shaft excavations were up to 50 feet (15.2 m) deep and were required to be designed watertight by using jet grouting or compaction grouting.