There are currently twenty eight (28) permitted active surface mines in Merced County. Existing mines are located throughout the County requiring extensive travel. In many cases the mines are clustered in relatively close proximity, allowing multiple inspections to be carried out in a single day. Past experience indicates that three to five mines can be inspected in one day. With one exception all of the operations involve gravel and sand extraction and processing. All sites can be accessed by conventional vehicles, although a four wheel drive vehicle is recommended.