COASTAL SAND MINING IN NORTHERN CALIFORNIA, U.S.A.

Abstract

The commercial mining of sand at coastal locations along California has been a continuing activity at some sites, sporadic at others and altogether discontinued at still other sites. This mining activity includes all methods of sand mining (dragline, self-propelled bottom-dump scrapers, diesel shovels, etc.) and may be classified by littoral zone location as (1) mining from a beach foreshore or backshore area wetted by the normal tidal range, (2) mining within a river mouth or other estuary upstream from the ocean but still within the tidal zone, and (3) mining from bluff or dune areas not wetted by the normal range of tides but still within the littoral system. Processing of the sand thus mined takes place when the material is transported from the mining site, usually by end dump trucks or belt conveyor to either a fixed or a portable plant. Commercial uses of the sand thus mined fall into two general categories, (1) construction and (2) special purposes. Construction usage includes aggregate for concrete, asphalt, mortar, plaster and stucco, base material in road construction, and fill and structural backfill. Specialty uses include sand blasting and filtration material, foundry and engine sands, and raw material for manufacture of glass and ceramics. Within the area studied (see Figure 1) the Monterey Bay area has the highest concentration of mining activity. To the north, the area around Fort Bragg yields significant quantities to the commercial miner. Most of the remaining coastal sand mining activity is concentrated in the San Francisco area.