Soil and groundwater at a residence in Woodside, California were impacted by fuel oil. The source of fuel oil was a fuel oil-fired boiler that was located in the basement of the house. Investigation was completed to discern the composition, magnitude, and extent of impact; and a cleanup plan was implemented. Soil vapor extraction was used to reduce impact concentrations in soil and groundwater, and concrete from the former location of the boiler was removed. A concrete vault that contained the remains of the boiler was discovered beneath the concrete slab. The vault also contained fuel oil that had leaked from the preheater tank. Work was done to remove the fuel oil and boiler from the basement and replace the concrete slab. A case closure letter was issued by the County regulatory agency upon completion of work.