Water will flow back and forth between Hodges and Olivenhain Reservoirs within this 10-foot diameter steel pipe. The pipe’s epoxy coat protects the steel pipe from internal corrosion. In total, 148 sections of pipe were used to complete the tunnel.

This is a “pipe carrier.” It was used to lift and place the steel pipe within the 1.25-mile-long pipeline tunnel

A mucking machine pushes the “pipe carrier” into the pipeline tunnel.

In this image, the pipe section is placed within the pipeline tunnel and attached to another installed section of pipe.

The pipe section is secured inside the pipeline tunnel using timber bracing. The bracing keeps the pipe from moving and allows the area between the outside of the pipe and the tunnel wall to be backfilled with grout.

One by one, each section of pipe is welded together and forms the pipeline inside the tunnel.

Construction equipment and materials used in the tunneling process are lowered and lifted in and out of the pump station pit using a crane.

Looking down from the top pump station pit, you can see the excavators removing material that has been blasted. The material is put in a dumpster-sized bucket and hauled out of the pit using a crane.

After construction crews completed excavation of the 12-story Hodges Pump Station pit in June 2007, construction of the pump station’s foundations, walls, and floors started. Here, a construction worker places steel reinforcing bars within the Pump Station floor. The reinforcing bars are encased within concrete to strengthen and hold the concrete together.

Construction crews started pouring the foundation of the pump station in June 2007. Here, concrete is lowered in a large bucket and poured onto the steel framework.

Another method of delivering concrete form the top of the pump station excavation to lower sections was the use of a concrete pump truck.

As concrete is poured, a construction worker smoothes-over and levels the concrete with an extension trowel.

Here workers smooth and level a floor within the pump station.

As construction continues within the pump station, steel reinforced walls are poured.

Some steel-reinforced concrete walls within the pump station reached ground level in April 2008.

As concrete work on floors and walls takes place, some of the water pipes and equipment is installed. This image captures the installation of equipment that will house the two pump turbines. The pump turbines will be able to generate electricity as water flows from Olivenhain into Hodges Reservoir. The pump turbines will also send water from Hodges Reservoir uphill 1.25 miles to Olivenhain Reservoir.

Equipment for the Lake Hodges Projects has come from all over the world. This 98-ton section of pipe is 21 feet in length and width and arrived on an oversized delivery truck from Fontana, Calif. on May 30. It connects the pump station to the 1.25-mile-long pipeline between the Hodges and Olivenhain reservoirs and split the tunnel’s water flow to feed two pump turbines housed in the pump station.

Electricity generated by the pump turbines will be transmitted to an outdoor switchyard. San Diego Gas & Electric’s construction crews started work on the switchyard in June 2007.

This 69kV, ¼-mile-long power line connects the electrical switchyard to the existing San Diego Gas & Electric local transmission system.

The San Diego Gas & Electric substation was completed in February 2008. The Water Authority will construct electrical facilities adjacent to the substation prior to the completion of the project.

At the bottom of the pit that will house the pump station, construction workers drill pilot holes horizontally towards Lake Hodges. This construction method is referred to as drill & blast method, in which pilot holes are drilled for explosive charges. Once the explosive charges are set-off, the resulting debris is carried out and the process is repeated.

The two-pronged inlet/outlet tunnel will draw or discharge water back and forth from the inlet/outlet structure, located at the bottom of Hodges Reservoir, and the pump station.

A cofferdam was constructed around the worksite in Hodges Reservoir. The cofferdam is a temporary enclosure from which water is pumped to create a dry area to allow construction of the inlet/outlet tunnel and structure.

The inlet/outlet structure will be located within the walls of the cofferdam. The structure will be submerged under water when completed.

The coffer dam walls are reinforced with shotcrete and rock-bolts, which support the excavation of the inlet/outlet structure.

Once construction of the inlet/outlet structure is complete, the temporary cofferdam will be removed.

The project site -showing the pump station excavation in the foreground with the coffer dam in the background- is expected to be completed in late 2009.