Almaden Quicksilver County Park

The Project Site, Upper Jacques Gulch, is located in San Jose, California within the Almaden Quicksilver County Park. The Gulch is a steep, narrow, and densely vegetated drainage, approximately 3,000 feet long with elevation change of over 600 feet and varies in width from approximately 10 to 50 feet. From around 1845 to the 1970s, mining and processing mercury bearing ores (cinnabar) were conducted on land now within the Park. Calcine, the waste material left after processing the cinnabar, was typically dumped near the processing area, including the hill slopes above the Project Site. During large rainstorms, water and gravity transported the calcine downhill to the Project Site, eventually depositing in drainages along the Gulch. Subsequent channel incision and erosion within the Project Site has reworked the calcine, providing an ongoing source of sediment downstream. In 2015, Roux was retained by Santa Clara County Parks to assess the extent of mercury impacts and develop alternatives to minimize the transport of mercury-containing sediments down the Gulch to the Almaden Reservoir. In order to achieve this goal, multiple assessments were conducted to delineate the area, collect soil/sediment samples, obtain XRF measurements, and conduct stormwater sampling. Roux, in collaboration with its expert teams (H. T. Harvey & Associates, Murray Engineers, Inc., and Aspen Environmental Group) prepared a Feasibility Study for the United States Environmental Protection Agency (USEPA, funding agency) and San Francisco Bay Regional Water Quality Control Board (leading oversight agency).