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temperatures were also recorded on quality con- trol checklists every hour. The retaining walls posed an entirely differ- ent set of challenges. The walls ran the entire 2.67 miles (4.29 km) length of the trail between the bridges on both sides of the trail. Many of these walls were located in the backyards of residents and some of the houses were very close to the walls, at times separated only by a 4 to 5 ft (1.22 to 1.5 m) pathway. ACR had to coordinate with the general contractor and owner’s engineers on a daily basis to ensure that the residents permitted ACR adequate access to their yards to perform the work. In addition, some of these homes maintained elaborate gardens and expensive landscaping, requiring specialized property protection. Specifically, one of the yards ACR needed to access housed a picturesque koi pond and an herb garden owned by a well-known chef. This garden is closely tended by a professional gardener, and the harvest is used in several restaurants (Fig. 7). Thus, ACR had to deploy multiple levels of pro- tection for the plants and planters from dust, debris, and overspray. Further, the retaining wall next to this garden was covered in decorative vines, and ACR had to coordinate with the chef’s gardener to ensure proper pruning or removal without unnecessary damage to the surrounding foliage. In other areas, ACR had to install tempo- rary framing on the outer edge coupled with protective mesh and tarps to ensure that the shotcrete work was not damaging homes and yards. ACR also encountered an area of retaining wall where the cap was directly above a residen- tial balcony. To perform removals and shotcrete repairs without damaging property below, two stages of protection were deployed. First, ACR installed a fabric tarp along the guardrail of the trail to keep debris from travelling over the side. Additionally, the area designated for repair was framed to ensure that all chipping debris would remain on the trail-side instead of falling to the balcony and property below. This one-sided formwork also gave the nozzleman something to shoot against. As ACR progressed along this 2.67 mile (4.29 km) jobsite, encountering different temperaments of residents, gaining permission to access the repair areas along the retaining walls ran the spectrum of difficulty. Significance to Project When compared to form-and-place repair techniques, shotcrete proved a far more efficient method of repair on the 36 bridges and miles of retaining walls that allowed for quicker comple- tion with excellent structural capability. As in all construction projects, time was of the essence. Fig. 7: Elaborate gardens of homeowners Many of the bridges required the erection of required covered repair areas that needed shoring towers simply to stabilize a severely thorough planning, preparation, and coordination Shotcrete • Winter 2015 33


2015WinterShotcreteEMag
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