John Klein: Project CX3 – The Great Grand Avenue Dig of 2009

by John Klein | December 9, 2009 | 18 comments

I know a lot of people are following the progress of Measure DD, but what is all that work in the middle of Grand Avenue? I did some checking and it turns out that PG&E is making really important infrastructure changes there. The name of the project is the “New Oakland C-X #2 115kV Underground Cable Project,” or “CX3″ for short. That is, three new electrical lines are being installed from 2^nd & Castro Street near Jack London Square (sub-station C) to Grosvenor & Park Blvd. (sub-station X); this is where the name CX3 comes from. The new lines will carry 115,000 volts to sub-station X, which is a transmission and distribution sub-station.

_{Sub-Station X at Grosvenor and Park Blvd.}

The route travels along Castro Street to MLK, then east along West Grand and Grand Avenue to MacArthur, and then to Park Blvd. The overall distance is 3.66 miles. The original cost estimate for CX3 was $40-$50 million, but it will probably go over that. It started in March 2009, although the El Embarcadero section between Grand and Lakeshore was done in 2008 so that it wouldn’t interfere with Measure DD work. The entire project is scheduled to be completed in September 2010.

The project was originally proposed by the California Independent Service Operators (CAISO) in late 2005 as one of seven critical infrastructure projects it had identified as vital to improving system reliability in California. These 2005 proposals came after a summer of rolling blackouts in southern California. CAISO is a non-profit corporation that is a consortium of power generators and transmission line owners. CAISO is organized under federal regulations which allow energy producers to team up to better allocate transmission space; match supply with demand; provide transparency in pricing and in the condition of the electrical grid; and to administer the generation and distribution of energy more efficiently, all by linking power plants and utilities under a federally-approved structure.

_{Sub-station C and 2nd and Castro Streets.}

Back on the job, PG&E retained Black and Veatch (B&V) as the general contractor. B&V is an international engineering and construction firm with projects all over the world. An intrepid engineer could work for B&V in a wide variety of foreign countries, including Columbia and Afghanistan, if they are up for it.

PG&E and B&V usually don’t do the actual work for this type of project since neither is able to maintain local crews large enough for it. For this, Underground Construction Company, Inc. (UGC) is the subcontractor that was selected to install the new system. UGC is based in Benicia and specializes in projects like CX3 and can pull together a large, local crew. Most of the crews, trucks, and equipment you see are part of the UGC team. UGC has a great team. If you could say there are such things as “heroes” on jobs like CX3, they would be the UGC workers. They are all smart, focused, hard-working, and safe. These men and women dig, climb, pound, cut, drill, push, grind, twist, sweep, carry, sweat, and drive all day while, at the same time, exhibiting a level of team-work and cooperation that you’ll rarely see. They have to work like this because they are doing a difficult and dangerous job.

So, what are they doing? They are placing four 6-inch and two 4-inch diameter conduits along the entire length. The electrical wire goes inside the 6-inch conduit (one of the four is a spare). Fiber optic cables will run through the two 4-inch conduits. The fiber optics won’t include cable, DSL, or any direct service to the public. The fiber optics are for PG&E operations, especially for earthquake and disaster recovery and will allow PG&E to pinpoint line breaks quickly and precisely in the event of a major disruption.

Obviously, the main work is the trench down the middle of the street. Placing the new lines in the middle of the street is the best method of installation, otherwise it would all go overhead, which would be a visual nightmare, even though it would be way cheaper and easier to install. There is no minimum depth of placement for the cable and the only requirement is that the new electrical lines must be placed below all other existing utilities. There are tons of existing underground utilities all along the route including old electrical lines, gas lines, water lines of all sizes, and sewer lines. There are very few linear sections along the route without existing underground utilities. All this makes excavation of the trench and placement of conduit very slow. The trench in the picture, which is about seven feet deep, shows conduit running under a big brown water pipe.

  
_{Electrical wiring and fiber optic conduit}

The conduit in the picture hasn’t yet been wrapped as a “duct package.” The final package will be about 30″ in diameter when wrapped in a lead-shielded rubber sheath. The lead in the sheath will confine any magnetism that might possibly occur. The sheath is also impregnated with heat sensor circuitry that will allow PG&E to monitor heat generating by the power flow along the entire line. Both the fiber optics and heat sensors are new technologies for PG&E within the last five years.

In some areas the soil is very wet and in others, engineers think the geology is unstable. Because PG&E must build the system to perform for many decades and even centuries, the conduit package is further re-enforced in the wet and unstable areas before it is buried. The re-enforcement consists of an additional sheath of one-inch thick rebars running parallel with the conduit package surrounded, as much as possible, by water-permeable filter cloth, all of which is buried in engineered gravel. The permeable cloth and gravel allow water to drain away from the conduit. When the extra reinforcement is used, the whole package is nearly three feet in diameter; approximately 30% of the 3.66-mile length of CX3 is prepared this way.

Once the conduit is installed and the reinforcement is complete, the trench is filled with a special “thermal concrete,” which is a type of concrete that is engineered to allow the heat produced by the electricity to dissipate properly. The original soil that was excavated out is disposed of at the Altamont landfill. The trench is then topped-off with new pavement at street level.

Generally, things seem to be going smoothly with the project although there were some difficulties threading the conduit package through a tangle of utilities that surround the BART tunnel beneath Telegraph and Grand. In fron of the senior center at Grand and Harrison, the soil was so wet and unstable that digging a trench wasn’t possible. A tunnel had to be bored down to a depth of 32 feet starting at Bay Street, then running past Harrison Street and up Grand across from Christ the Light Cathedral.

_{Grand Avenue near Harrison}

There are about 100 people working on the project on any given day, I think. No one with PG&E, B&V, or UGC would talk about this so I counted every worker I saw at four different work areas along the project route on a typical day. At the same time, I counted 11 dump trucks, 14 pick-up trucks, 4 really big front-end loaders, 20 service vehicles (over-sized pick-up trucks with flatbeds and carrying racks), 6 Oakland police cruisers, 3 concrete trucks, 6 backhoes, five 16′-to-20′ long flatbed trucks, 2 really long flatbed trailers, 7 portable toilets, 2 large excavators on roller tracks, and 2 vans with trailers hitched to the back. I’m sure I missed a few people and pieces of equipment, but you get the idea.

For right now, UGC is placing the conduit without any wiring inside. B&V will come back in early 2010 and begin pulling the wire through the conduit. They will use access points at manholes and service areas, called “communication boxes,” that have been built into the system every 1,200 – 2,000 feet. The wire pull operation will not be as disruptive as the construction, but there will be large trucks with huge spools of wire on them parked in the road during that operation.

_{Workers on Grand Avenue near Perkins Street}

The City of Oakland wanted CX3 finished before the 2009 holidays, but it looks like they didn’t quite make the deadline. Although Grand Ave. is nearly complete, the tunneling in fron of the senior center put that section behind schedule. The trenching and conduit installation on Castro Street is about 75% complete, it appears, so it looks like traffic disruptions shouldn’t be too bad.

In any case, there is still a substantial amount of work left tying the new lines into the substations at both ends. At sub-station C, an entire new section will be built in the lot next to the existing portion of the sub-station. Just up Castro Street from this sub-station at 3^rd Street, a huge new underground communications box will be installed in a couple of weeks and will require three crances to place it into the hole now being prepared for it. At sub-station X on Park Blvd., another tunnel was needed between the street and the building to allow a new circuit breaker to be installed. This is not a circuit breaker like the one in your closet or garage, but rather is the size of a mid-size car.

So that is the story of the “dig” on Grand Ave. I thought it might be worth investigating CX3 and letting everybody know. I’d never seen any public information about it even though it’s such a big and important addition to Oakland. You can see more photos on Flickr.