Union Square, downtown San Francisco

Union Square, downtown San Francisco

Union Square

This project involved the complete stripping of two acres of the street level surface of Union Square in downtown San Francisco to make way for a new community area. Difficult conditions, in a highly congested area made for a challenge. Traffic patterns in the area were a coordinated effort by all parties involved to ensure pedestrians and automobile traffic was not impacted. All planter boxes, paving and concrete topping slabs were removed, as well as the soil, which was hauled to Golden Gate Park for reuse by the City. Granite planters were salvaged and sold for reuse. All demolition activities occurred over an active operating four story underground parking garage. Several hundred loads of dirt and concrete debris were removed from the site. Great care and safety was given to assure the safety of all in this high density shopping district.

Silverado Contractors was selected to remove 3,000 tons of existing park improvements and excavate 4,000 tons of lead contaminated soil from Union Square in San Francisco. The excavation, and removal of improvements, including recycling of the old granite planter walls, was done adjoining active city streets and above an active parking structure.


 
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270 Brannan Street

270 Brannan Street will be a 202,000 gross square foot, Class A office building in the center of San Francisco’s SOMA District. The project’s irreplaceable location at 2nd and Brannan is at the heart of SOMA, San Francisco’s most desirable neighborhood for technology companies. Silverado was contracted to perform hazardous soil remediation, demolition of an existing concrete structure, sitework and mass excavation, rough grading and backfill. Asbestos abatement was performed prior to demolishing the existing 17,350 SF 2-story office building. Also demolished was an elevator/hoist and existing sidewalk and 23,933 SF of asphalt-pave parking area hardscape and landscape including rails, railroad ties, parking attendant shed, trees, bollards, signs, fences, power station and street lights/poles.

Mass excavation of 20,000 cubic yards occurred. Hazardous soil remediation was performed, handled and disposed of properly. Installation of sheets and shoring the excavation with all required tiebacks and bracing were in place. Due to the proximity of the adjacent buildings, great care was taken to insure that they remained undamaged. Because the structure was concrete block we were able to carefully demolish the property line walls by munching them down with an excavator with a thumb and bucket. Protection was placed on the walls to ensure safe operations.

 

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Yerba Buena Island

Caltrans contracted Silverado to demolish the existing two story Treasure Island Fire Station to create access for the construction of the new Bay Bridge approach to the island. The contract also required the installation of a temporary shoring system to allow for a careful excavation of the site. Silverado worked closely with an archaeology team studying the remains of an Ohlone Indian seasonal camp that existed on the island before the westward expansion.

Excavation of hazardous soil within an archaeological area requires extreme caution and precision. Silverado worked on an hourly time and materials basis assisting with the archaeological team that was investigating the site. This teamwork approach yielded a cache of shell, bone, and artifacts, dating to 12,000 B.C. Archeologists also found artifacts from a family who had lived on the island between 1849 and 1868 and remains from the U.S. Army's Post and Depot. Among the many artifacts found were ironstone plates, ink and beverage bottles, metal and bone buttons, eyeglass lens, a whetstone, and an 1854 Canadian token.

 

excavation of 2,500 tons of soil

excavation of 2,500 tons of soil

Sacred Heart Preparatory High School

This project involved the construction of a new theater in the middle of an existing building, which required the containment and excavation of 2,500 tons of soil. A custom debris ramp was build and installed to allow safe removal of the soil while giving students needed access.

 

9th Mission Jessie

9th Mission Jessie

9th and Jessie

Silverado Contractors was contracted by Cahill Contractors to perform the mass and structural excavation for a new 12 story, HUD funded low income residential structure. Due to the past use of the site the sand was contaminated with high levels of lead from the 1906 earthquake burn zone. In all 5,200 tons of material was hauled from the site. Also included in the scope of work was the backfill, compaction and installation of the subgrade rock for the new mat slab.

 

 

University of San Francisco Science & Innovation Center

University of San Francisco Science & Innovation Center

University of San Francisco Science & Innovation Center

University of San Francisco had plans for the construction of a 6-story classroom/laboratory building with a floor area of up to 60,000 gross square feet. Silverado was contracted to perform the site demolition, mass excavation, grading and structural excavation for their new Science and Innovation Center. The project presented both logistical and environmental challenge entailing the excavation of 23,000 cubic yards of serpentine contaminated soil. In the process, over 60 graves sites were uncovered. A century ago, the job location had been one of the City’s first cemeteries. With careful work in coordination with University archaeologists, the remain were removed and the project was completed on time.