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ent just a few feet (meters) below the bottom of the proposed garage excavations. The site also had historical wildcat dumping decades ago; thus, sorting and then legal disposal of debris was required from the beginning of the site work. The proposed project plan by the development team included a parking garage with a 19 acre (77,000 m2) footprint, two levels below street grade approximately 24 ft (7 m) deep, podium layout construction, with five individual glass office towers within the garage footprint. The total office space of the five buildings was 2 million ft2 (190,000 m2), and 60,000 ft2 (5500 m2) of retail space. The development was proposed to maximize the land parcels and therefore the below-grade garage footprint was pushed out to near the property lines, requiring shoring systems to be installed at the wall line—or, in other words, at the back of the proposed perimeter finish wall. In 2013, the project was initially programmed to be constructed at a project cost of $600 million to deliver shell buildings and completed sitework. Subsequent scopes and contracts were to include build-to-suit space and furnishings for the buildings. These final scopes are being finalized and completed, and will be ready for occupancy this spring of 2017. Occupancy of some building spaces began sometime last year. The size of this project in terms of dollars and area is the largest ever in the metropolitan Phoenix, AZ, area, just edging out CityScape, where Buesing also performed the three similar scopes in 2008. Once the Marina Heights land closed escrow, the pressure was on to begin construction. Ryan Companies solicited budget pricing based on preliminary schematic drawings to more than three bidders for the sitework, shoring, and concrete/shotcrete walls. Buesing was successful in being awarded all three of these scopes on this project and swiftly began collaborating with the project team on all aspects, including removals, mass excavation, shoring/earth retention, and shotcrete finish walls. In this process, we refined the guaranteed maximum price (GMP) type budgets for contract, and collaborated on detailed schedules and work plans. Buesing began sitework within 2 weeks of being awarded the contract because of the fast-track nature of this project. Although mass excavation, sorting and hauling debris, hauling excess soil, and shoring all began in late July 2013, the concrete trade subcontractor (Suntec Concrete) was immediately behind Buesing starting the concrete mat foundations, interior columns and shear walls, and perimeter wall reinforcing bar installations. By November 2013, we began installing shotcrete finish walls in some limited areas while we were still excavating and shoring in other areas. It is also interesting to note that our temporary shoring system included a 4 in. (100 mm) thick shotcrete facing, which required daily crews to keep the shoring operation on schedule. Therefore, oftentimes we were installing shotcrete facing for shoring with one crew and installing the permanent, perimeter shotcrete finish walls on the perimeter with a second crew. SHOTCRETE WALLS The structural or finish perimeter walls for the below-grade garage were initially designed to be conventional form-and- By the Numbers • 19 acres (77,000 m2) of garage footprint • 470,000 yd3 (360,000 m3) of mass excavation and haul off • 105,000 ft2 (9750 m2) of shoring/earth retention (three systems) • 97,000 ft2 (9000 m2) of permanent shotcrete finish walls Fig. 2: Buesing Corp. setting ground (piano) wires from scaffolding (reinforcing bar curtain by concrete subcontractor) Fig. 3: Nozzleman shooting shotcrete (wet-mix) for structural finish wall Fig. 4: Multiple shotcrete activities on three levels of scaffolding www.shotcrete.org Spring 2017 | Shotcrete 57


2017SpringShotcreteEMag
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