Water supply from a mountain lake atop Donner Pass in the Sierra Nevada Mountains (7,056 foot elevation) was at risk of arsenic contamination twice due to local homes using heating oil.
The emergency well for this lake was located within a well house, which was covered with 10 to 15 feet of snow each winter. This prevented access for 4–5 months per year, meaning that the required arsenic removal system had to exist in a permanent stand-by condition and create no backwash. If the system needed to be used during the winter, it would have to function without startup maintenance and run for months. The well house also had a low ceiling, so the system needed to be designed to fit within the existing unmodified building.