Value at Award: $987,000 - Value at Completion: $987,000
Yerba Buena was the prime contractor for this NPS project performed on Alcatraz Island, San Francisco, CA. The scope of work included installation of a six-inch water main that ran from the bottom to the top of Alcatraz Island. As part of the construction effort, Yerba Buena had to access the utility trench through large concrete doors; it was anticipated during project scoping that the doors would crack and break requiring replacement of the concrete doors to match the original structure. Yerba Buena was tasked with developing a paste and aggregate mixture to match the historic doors exactly. This was accomplished through a trial and error process that required mixing and testing onsite.
The scope of work also included coating two, large 10,000-gallon water tanks. The tanks were presumed to be in good condition during the bid process. However, Yerba Buena determined the tanks had severe deterioration due to salt-water exposure. The situation was communicated to the NPS and an addition was made to the scope to include restoration of the tanks.
Another challenge during construction was the discovery of asbestos once the trench doors were opened. Yerba Buena also used the night shifts to maintain egress and fire-protection systems during construction. Since the island is not Americans with Disabilities Act (ADA)-compliant, a tram is used to transport people and emergency crews as necessary and was thus required to be operational at all times. Yerba Buena’s night shifts ensured continual functionality for all emergency services.
Yerba Buena was required to protect natural and cultural resources during the performance of this project. During performance on the water tanks, Yerba Buena was instructed that they could not disturb nearby nesting birds for a six-month period. Yerba Buena worked with the natural resource experts to develop a solution that would enable to project to continue while also protecting the birds. The water tanks were concealed with a shrink-wrap tent to protect the birds’ vision of the towers as well as protected tourists from potential debris and work crews from severe weather exposure. Tourist safety was also ensured through alternate work schedules and the use of high-strength concrete which set-up faster and eliminated area downtimes.
The work was performed on rugged terrain under difficult climatic conditions, including repairs made to concrete exposed to high chloride levels found in marine environments Located in an area experiencing severe weather such as frequent high winds, sleet, rain and fog, Alcatraz Island presented many challenges. Yerba Buena focused on maintaining flexibility, working alternate schedules as much as possible to plan for future weather-related delays. The tenting of the water towers also enabled performance during severe conditions to ensure continual progress. Project Duration: 11/06-12/07.