Silverado was contracted to perform the mass and structural excavation for a new 11 story, HUD funded low income residential structure for seniors in San Francisco. 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.