Pumped Mat Slabs Replace Multiple Piers For Fast Track Solar Panel Plant
In the seismic areas of northern California, earthquake engineering is a fact of life. In the case of a solar panel manufacturing plant being constructed in Fremont, CA, the engineers chose a keyway system to tie large concrete mats together in place of drilling and filling hundreds of piers for the foundation. The expansion of Solyndra, Inc.’s manufacturing capabilities will add 609,000 square feet of production and office area. The company has a nearby plant in the Bay Area and the new expansion is named Fab 2. The 100-percent pumped project is being handled by Joseph J. Albanese, Inc, Santa Clara, CA working with general contractors Rudolph and Sletten, Redwood City, CA, a wholly owned subsidiary of Tutor Perini Corporation.
Albanese has been on the site since September 2009 and has placed a total of 130,000 cubic yards as of 2/16/2010. “The engineers came up with a keyway system to join the 69,000 cubic yard mat pours, explains Mike Aldrich, pump division manager for Albanese.” Albanese, a self-reliant construction firm with 16 boom pumps whose motto is “We Just Get It Done!” has been doing just that as the place and finish contractor for the two story structure that will incorporate a concrete roof as well.
“We have had two to three pumps on the project everyday, “Aldrich noted. The company began by pumping ‘rat slabs’ – four inch thick ground cover to set the millions of pounds of rebar that is incorporated into the 12 mat slab pours. The slabs are poured with custom forms to provide up to10-foot deep keyways that stabilize the foundation. The 12 mats were poured one at a time with 4 to 6 pumps participating to place up to 7000 yards in 12 hours. “Because the site is in an urban, industrial area, we begin pouring at four in the afternoon and end up at four in the morning,” according to Aldrich, “We have tight access so there is only room for one set-up for each pump.” Three Central Concrete ready-mix plants supply the 4,000 psi 6” slump mat slab concrete that was a 70% cement replacement mix.
The 47, 58 and 61 meter boom pumps used on the project from the Albanese all-Schwing fleet incorporate four-section Overhead Roll and Fold® Booms which provide a 180-degree articulating main section. This allows the first boom section to be angled away from the pour and gives the operator added convenience to guide the other three sections into the building. This is particularly useful on the Solyndra project because steel is already erected as the crews pump the 12-inch slabs on grade through up to 300-feet of 4-inch hose attached to the end of the booms.
The construction of the plant is being aided by Department of Energy financing which has resulted in additional inspections and an increased emphasis on safety. Consequently, trench plates are pre-set before each pour for outrigger support. Aldrich noted, “The Super X outriggers used on all Schwing long booms have as much as 12.5-percent less outrigger soil pressures than other models.“ The Super X one-piece outriggers also allow a 25-percent smaller footprint and telescope out and around job site obstructions. This has been an asset for the pumping crews on the hemmed in site.
“Safety is always a major concern for Albanese,” states Aldrich, “We believe in ACPA certification of our pump operators and I’m sure that is a plus when we are considered for these projects.” ACPA guidelines call for recertification within two years for all operators, which Albanese endorses, “The newer operators have a higher safety awareness. It is the veteran operators that may have become too routine in their actions and need an occasional refresher.”
Added work for Albanese pumping crews came in the form of 34,000 cubic yards of controlled density fill. “Because the tops of some of the mat slabs were six feet below grade, they were going to add dirt and a course of pea gravel to elevate the grade,” Aldrich explains, “This cementious controlled density fill is a pumpable product that does not require compaction and went in fast while providing better support.” The crew also pumped 3,000 yards of walls below grade as permanent forms for the flowable fill.
Twelve-inch topping slabs were pumped in a checkerboard fashion. These pours were 10’ by 190’ with machine finishing to a FF40 flatness specification. The four-inch slump concrete is being provided along with the 2nd floor and roof concrete by Cemex. Currently, concrete placement is occurring in all sections of the building from slabs on grade to second story decks and the roof. “We could not do this job without the long booms we have on this project,” states Aldrich. He reports 100-percent uptime from the pumps which utilize a slow-stroking design with 10-inch diameter, 98-inch stroke material cylinders for smooth output and less wear. “Whether it was the 58 with full five-inch line or the 61 with its four and one-half inch pipe, the pour rate was never held up by the pumps,” Aldrich stated.
In the ultra-environmentally sensitive climate on construction sites today, the requirements for clean-out were even more strict on the Solyndra project. A lined pond was provided by the general contractor for wash-out. The Schwing Rock Valve requires less water for the rinsing process, than other valve types, which helps project personnel to maintain the level of the washout pit.
The company lives up to its motto. “We Just Get It Done,” adds Aldrich. The company owns more than 400 pieces of construction equipment including excavators, scrapers, loaders, backhoes and paving machines in addition to their concrete pumps. Their employee roster numbers more than 800.
“We bought the 61 for a bridge job four years ago and it wasn’t long before we bought a 58-meter,” recalls Aldrich. Two years ago, a customer needed a long boom for an unexpected 500 yard afternoon pour and called at eight in the morning. “We were able to free up one of our pumps and put together a placing crew to get it done.” Albanese has grown their pumping fleet from four pumps seven years ago to their current fleet size by pumping for other concrete contractors in the Bay Area. Albanese performs in a wide range of concrete construction services, including: place and finish, architectural walls, staining and stamping, curb and gutter, and even fountains. Albanese also has demolition, grading and paving, trucking, and saw-cutting divisions.
Concrete placement is expected to continue on the Solyndra Fab 2 site until May 2010. This will complete Phase 1 of what promises to be further plant expansion for the manufacturing of the company’s popular cylindrical, photovoltaic, thin film systems which are designed to generate more electricity on an annual basis than typical low-slope commercial rooftop units. The new facility will enable Solyndra to fulfill its announced contractual backlog of over $2 billion and create additional jobs. Solyndra’s two Fabs in northern California will produce enough solar panels over their lifetime to cut over 350 million metric tons of CO2 emissions or 850 million barrels of oil. The 500 megawatts generated by their annual output of solar panels is enough electricity to supply 150,000 homes.
Project: Solar Panel Manufacturing Plant, Fremont, CA
Owner: Solyndra, Inc., Fremont CA
Architects: STUDIOS Architecture, San Francisco, CA
General Contractor: Rudolph and Sletten, Redwood City, CA
Concrete and Pumping Contractor: Joseph J. Albanese, Inc, Santa Clara, CA
Equipment: Schwing S 47 SX , S 58 SX and S 61 SX truck-mounted concrete pumps with placing booms